Phenol Process Celebrates Its 60th Anniversary - ILLA LLCd/process/zakosanskii.pdf · Phenol Process Celebrates Its 60th Anniversary: ... and acetone through a cumene feed-based process,

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 10, pp. ????–????. © Pleiades Publishing, Ltd., 2009.

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Phenol Process Celebrates Its 60th Anniversary: The Role of Chemical Principles in Technological Breakthroughs1

V. Zakoshansky

ILLA International, LLC, 4756 Doncaster Court, Long Grove, IL 60047-6929, USA

e-mail: [email protected], [email protected]; http://www.illallc.com

Received September 5, 2009

Abstract―This article provides an overview of the chemical principles of achieving the highest possible selectivity in the modern process of simultaneous phenol and acetone production on the basis of the achievements in technology developed by ILLA International, LLC, that has been successfully implemented in many plants all over the world. The article also demonstrates solutions by which the ILLA’s process has the potential to become virtually wasteless.

1 The text was submitted by the author in English.

The total annual worldwide production of phenol and acetone through a cumene feed-based process, in 2009, its jubilee year, has reached about 10.5 million tons per year and about 6.5 million tons per year, respectively, a considerable achievement for this process, making it one of the highest production capacity petrochemical processes.

Commercial implementation of this process was made possible as a result of discoveries, totally inde-pendent of one another, by R.Yu. Udris (Russia) in 1942 [1], and by H. Hock and S. Lang (Germany) in 1944 [2], of the acid-catalyzed reaction of cumene hydroperoxide (CHP) cleavage into phenol and acetone.

The cumene oxidation reaction has been known since 1926 [3], i.e., for a relatively long period of time, prior to the discovery of the abovementioned CHP cleavage reaction. The original practical purpose of cumene oxidation was the production of acetophenone, rather than of CHP [4]. The discovery of the reaction of CHP conversion into phenol and acetone changed the principal practical approach toward the cumene oxidation reaction, directing it for implementation in CHP production [5]. These two chemical reactions, cumene oxidation into CHP and acid-catalyzed CHP

cleavage, laid the foundation of the two primary commercial methods for phenol and acetone produc-tion that, while based on the same chemical reactions, were nevertheless substantially different from one another in terms of their process implementation. The achievements of the pioneers, the Russian, German and British researchers and engineers, who started up, independently and almost at the same time, the first commercial phenol and acetone production plants in 1949, both in Dzerzhinsk, Russia and in Montreal, Canada, certainly deserve the highest respect. On the other hand, it should be noted that the actual implementations of both of the process methods demonstrated low process selectivity and were potentially dangerous in operation and harmful to the environment.

It is also worth mentioning that the concerns about the negative environmental impact of those early commercial processes actually stemmed from their low selectivity, and more specifically from the formation of huge amounts of undesirable and difficult-to-dispose of waste products, the so-called ”phenol tar,” reaching quantities of about 150, or even of 200–250 kg per ton of phenol product. The majority of these waste products were actually produced at the output of the CHP cleavage stage, with a CHP feed (technical grade CHP) also containing by-products of cumene oxidation, such as dimethylbenzyl alcohol and acetophenone.

DOI: 10.1134/S1070363209100272

RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 9 2009

ZAKOSHANSKY 2

However, despite numerous and persistent attempts by various researchers, involved in different aspects of the phenol industry throughout the world, to achieve any significant level of improvement of the selectivity value of the phenol processes that were invented by the pioneers, the outcome nevertheless remained poor over the course of more than four decades from the time of the invention of the original phenol process. More importantly, this continuing pattern of failures to improve the original process even resulted in many “experts” taking the position that the original process invented by the pioneers was already at its maximum possible level of selectivity and, therefore, continuing any further research, and related efforts, to improve the original process, would be a waste of resources.

An examination and analysis of the causes of the lack of any measurable success in improving the original process, has demonstrated [6], that the overwhelming majority of previous failed attempts to improve the process performance were based on the erroneous presumption that it was possible to attain the sought-after improvement through only a partial and insignificant modernization of process implementation, while essentially ignoring the chemistry of occurring reactions. Avoiding this pitfall, ILLA International, LLC, which has recently developed and designed a cutting edge modern process based on innovative chemical and process approaches (essentially positioning this process as being “state-of-the-art” in the 21st century), commenced an in-depth study of the mechanisms and kinetics of all chemical reactions occurring in the process in question, thus laying a science-centric groundwork as a foundation for, and a path to, future success. At the same time, the knowledge of various aspects of the old process technologies, and of the failures of other researchers, accumulated over years by its experts, was utilized by ILLA to its advantage, as a valuable marker enabling identification and avoidance of approaches that should be discarded as being non-viable and/or even as being unacceptable in up-to-date commercial process design. As a result, the only features of the original phenol processes (and their next generation improvements) that are in common with the modern up-to-date phenol process [6], are (1) the introduction of cumene as an initial feed, and (2) the production of phenol and acetone as the desired pro-ducts. Even the chemistry of the reactions, disclosed in [6], not to mention the design of the process itself, have been markedly changed. Nevertheless, without this giant leap forward, the current worldwide success of ILLA

International’s processes would be absolutely impossible.

Furthermore, rather than relying on an outdated conventional one-level process protection design, a fundamentally novel three-level philosophy of an integrated process protection/control system was implemented as a component of ILLA’ technology for CHP cleavage, potentially the most dangerous stage of a phenol process. This approach also enabled ILLA to achieve online control over the CHP conversion value: goals that were not achievable within the framework of previous generations of process design.

As a result of the proper implementation of the abovementioned advantageous principles and solu-tions, ILLA was able to reduce the phenol tar yield by about 6 to 10 times (from about 150–250 to about 25 kg t–1 phenol), thus establishing the process with a place of honor among unique large capacity petrochemical processes, in terms of actual levels of achieved process selectivity (about 97 mol %) and high process safety. All of the above issues, factors, and considerations, inclusive of a retrospective process review, starting from the initial invention of the original cumene-based phenol process, as well as an analysis of currently existing relevant technologies, are presented in far greater detail in a treatise, by the author of this article, entitled “Phenol and Acetone: An Analysis of the Process Technologies, and of the Kinetics and the Mechanisms of Correspond-ing Major Reactions,” published in early 2009, an anniversary year for the phenol process (see [6]). This article only focuses on providing an understanding of the basic chemical principles that have markedly changed from the time of the original phenol pro-cesses, as well as on the prospects of creation of the next generation phenol process, that will be advantageous, from the viewpoints of process selec-tivity and economic benefits, when compared to even the best cumene-based phenol processes in existence in the beginning of the 21st century.

Cumene Oxidation

The previously held classical notions, that the cumene oxidation reaction is completely promoted by dissolved oxygen (O2

liquid), as noted in [7], have been proven wrong. Unfortunately, the unjustified belief in the accuracy of this assumption of the sole source or reaction promotion, had led researchers astray in their search for new methods or process improvements, capable of increasing the process selectivity value.

PHENOL PROCESS CELEBRATES ITS 60th ANNIVERSARY


3

Recent detailed studies [8, 9], provide clear experimental evidence that: (1) the desired oxidation product, CHP, is mainly produced with participation of gaseous oxygen (O2

gas) at the liquid-gas interface, (2) the major by-product of the process, dimethylbenzyl alcohol, which affects the selectivity of cumene oxidation to a significant extent, is formed with the participation of dissolved oxygen (O2

liquid), and (3) the formation of acetophenone proceeds by three independent paths, i.e. under the influence of O2

gas and O2

liquid, as well as through thermal decomposition of CHP [8]. These studies clearly reveal that the actual chemical scheme of acetophenone formation is completely different from the one proposed under conventional views [10]. Therefore, acetophenone formation should in fact be described by the simplified gross scheme (2), rather than by the scheme (1):

of dissolved oxygen (corresponding to a higher reactor pressure), is favorable for greater proportions of these by-products formed under the influence of O2

liquid. The relationship between the quantity of CHP and the total amounts of acetophenone and dimethyl-benzyl alcohol formed under influence of O2

liquid, equals about 1 : 1, which supplies clear evidence of a very low selectivity (about 50 mol %) of CHP conversion with participation of O2

liquid. The only factor preventing a commercial cumene oxidation process from experiencing such poor performance, is the very high selectivity (about 95 mol %) of oxidation promoted by O2

gas, taking into consideration a very large fraction of CHP formed through O2

gas at the liquid-gas interface, as compared to the reaction of cumene with dissolved oxygen in the liquid phase. As a result, the total selectivity of cumene oxidation (through both O2

liquid and O2

gas) is about 90 mol % (at temperature of about 110°C, and under pressure of about 3 kg cm–2). Certainly, a decrease in the degree of cumene conversion, as well as in the temperature and pressure in commercial bubble-type reactors, predictably increases the magnitude of total process selectivity, while at the same time significantly decreasing the throughput of the oxidizers (and, correspondingly, the CHP output rate per unit volume of the oxidizer). Increasing the degree of cumene conversion partially solves this problem, but simultaneously leads to accumulation of inhibitors, such as phenol, aldehydes, etc., in the oxidation mixture, thus dramatically restricting the potential for achieving high concentrations of CHP in the oxidate, and thereby decreasing the magnitude of process selectivity.

However, notwithstanding the above discussion, the experimental evidence of a substantially greater fraction of CHP being formed at the liquid–gas interface, and the nearly twice greater selectivity of the CHP formation reaction promoted by O2

gas, leads one to the conclusion that further improvement of the process selectivity (i.e., to more than 95 mol %) is expected to take place through a shift from the oxidation reactions occurring in the liquid phase, toward the reactions occurring at the liquid-gas interface, with participation of O2

gas. Preliminary calculations demonstrate that the process selectivity can be increased to as much as 98–99 mol %, without compromising a commercially acceptable CHP output rate from the reactors. Although at the present time such a statement may appear to be nothing more than a pipe dream, one can never forget that the selectivity of dimethylbenzyl

The overall gross scheme of cumene oxidation with formation of CHP, dimethylbenzyl alcohol, and aceto-phenone appears below:

Analysis of experimental data, and of the corres-ponding calculations, demonstrates that the proportions of acetophenone and dimethylbenzyl alcohol formed under the influence (with participation) of O2

liquid, with respect to the total quantities of acetophenone and dimethylbenzyl alcohol formed during cumene oxida-tion, are about 40 % and 50 % (relative), respectively (at temperature of about 110°C, and under pressure of about 3 kg cm–2 [8]. Moreover, a higher concentration

CumeneO2 ,

liquid

Acetophenone

Cumene hydroperoxide

T, °C O2 ,gas

T, °C

Dimethylbenzyl alcohol

O2 ,liquid

O2gas

(3)

(1)

(2)

CumeneO2

liquid

Acetophenone,

Cumene

O2liquid

O2gas

O2liquid

O2gas

Cumene hydroperoxide T, °C

Acetophenone


ZAKOSHANSKY 4

alcohol conversion into α-methylstyrene at the CHP cleavage stage exceeding 90 mol %, was likewise commonly considered to be a “fantasy” before the year 2000, at a time when even the best processes achieved as much as about 50 mol %. Nevertheless, the “absolutely fruitless fancy,” as it was treated by many who presumably had expertise in this complex and challenging process, has now turned out to be reality – the maximum α-methylstyrene yield achieved in commercial practice is 92.8 mol %, and many plants using the unique technology [11] have an annual average selectivity for α-methylstyrene of about 90 mol %, which marks a real breakthrough in the phenol industry. In the context of a cumene oxidation process, one should keep in mind the unconventional novel chemical approaches that appear to be the basis for new solutions for effective control over radical chain reactions which were earlier considered nearly uncontrollable. The core basis of these solutions is making a change in the relationship between the concentrations of radicals and inhibitors (R·/In and ROO·/In) that enables a CHP concentration of 62 wt % in the oxidate to be reached (see Fig. 1, curve 2), without a corresponding abrupt decrease in selectivity value, which is a clear distinction from the usual pattern (Fig. 2) observed even at a smaller CHP concentration (e.g. 40 wt %), ending with complete cessation of oxidation process, as illustrated by curve 1 in Fig.1).

The abovementioned facts provide a solid ground for the expectation of additional considerable break-through in cumene oxidation process development in the relatively near future. Such considerable improvements in oxidation process design are, in turn, expected to contribute to another breakthrough by way

of synergy, resulting in the improvement of the selectivity of the entire phenol process, in a similar manner as had occurred when the range of development, experimental, and research tasks related to a CHP cleavage process, which had commenced in 1975, were finally completed by ILLA in 2001.

Cumene Hydroperoxide Cleavage

The CHP cleavage stage is an essential part of a phenol process. At the same time, it is one of the most complex process systems, and its potential for dangerous accidents and similar risks is ranked extremely high among other large capacity petrochemical processes. The extreme complexity of CHP cleavage is readily explained by the vast diversity (more than 60 in number) of the chemical reactions involved in the process, and the main source of its extreme potential for dangerous accidents is the presence in the process of an explosive chemical compound such as CHP, the decomposition of which releases immense heat at a very rapid rate (i.e., in the space of several seconds), forcing the operators of a commercial process to remove the heat of reaction at an equally fast rate. Moreover, the process should be configured in such a manner as to avoid, or at least to minimize, the formation of undesired by-products and, correspondingly, to maximize the yield of three desired products, specifically phenol, acetone, and α-methylstyrene, the latter being formed from dimethylbenzyl alcohol, appearing as a by-product of cumene oxidation. It should also be noted that the CHP cleavage stage is crucial to the ultimate safety level and selectivity value of an entire phenol production facility [6].

A supplemented general scheme of chemical reactions involved in the cleavage of CHP feed

Fig. 1. Cumene oxidation at T = 110°C and P = 5 kg cm–2. (1) Cumene, without pre-removal of inhibitors and (2) Inhibitor-free oxidate.

Fig. 2. Process selectivity vs. CHP Concentration at T = 110°C and P = 5 kg cm–2 (in the experiment without pre-removal of inhibitors).

[Cum

ene

hydr

oper

oxid

e], w

t %



5

containing dimethylbenzyl alcohol, acetophenone, and other impurities entering this stage from cumene oxidation, is presented in Fig. 3.

Cleavage of CHP feed involves very diversified and complicated chemical conversions (see Fig. 3), in

which dozens of both reversible and irreversible reactions occur simultaneously. In such a case, the challenge of finding a single technique to maximize the yield of three target products (phenol, acetone, and α-methylstyrene), inevitably becomes a vicious cycle. The presented scheme clearly demonstrates the

Fig. 3. General chemical reactions of cumene hydroperoxide feed cleavage.

Cumene hydroperoxide

Dimethylbenzyl alcohol

C−Ο−Ο−ΗCH3

CH3

CCH3

CH2

α-methylstyrene

C−Ο−ΗCH3

CH3

Cumene hydroperoxide +

Acid-catalyzed cleavage

H+

C−Ο−Ο−CCH3

CH3

CH3

CH3

Dicumyl peroxide

O−CCH3

CH3Phenylcumyl ether

CCH3

CH3

O−H

Cumyl phenols

CCH3

CH3

O−H

α-Methylstyrene dimers

+ phenol

Polyphenols

CCH3

CH2

O−H CH3−C−CH3

OAcetone

Phenol

+ H+, ROOH

CH3−C−CH2OHO

Hydroxy acetone C−CH2CCH3OH O

H3CH3C

Diacetone alcohol−H2O

C−CHCCH3H3CH3C

Mesityl oxide

+ phenol

+ dimethyl benzyl

alcohol

+

O


ZAKOSHANSKY 6

chemical complexity, and even the practical insolvability at that time, of the problem facing the inventors of the first commercial processes. Therefore, it is not at all surprising that no breakthrough in achieving maximum process selectivity was possible, without knowledge of (1) the detailed kinetics and mechanisms of the reactions involved, of (2) the unique properties of the reaction medium in which the reactions occur, and of (3) the essential changes in the properties of H2SO4 used as an acid catalyst with a changing composition of the reaction medium.

Even in its infancy, phenol production was transforming into a large capacity commercial process at a rapid pace, that eventually set the goal of achieving a selectivity improvement as the critical issue. Over the period of almost four decades from the invention of the original phenol technologies, researchers in the field of phenol production processes, and most manufacturers of phenol products, were persistently attempting, although without measurable success, to find methods for improving the selectivity of the CHP cleavage stage of the process. Hundreds of scientific papers and patents were written and published, and some progress in commercial process design was made, but no considerable improvement of the selectivity value was achieved. Accordingly, the yield of non-disposable wastes remained very high, ranging at about 150–180 kg per ton of phenol product.

Having failed to enhance process selectivity by the use of chemical methods, i.e., in the context of chemical conversions presented in Fig.3, the researchers tried to improve the performance of a phenol process through development of advantageous solutions for its finishing stage of waste treatment, including, in particular, a technology for high-temperature cracking of phenol tar. The fatal flaw of this strategy was clearly demonstrated in the course of commercial operation of cracking technologies. While, on the one hand, implementation of the cracking stage somewhat reduced cumene usage per ton of phenol product, it caused a number of serious problems listed below:

– Substantial increase in operational complexity of a cracking system;

– Formation of additional by-products and a considerable increase in the quantities of impurities, that have a very negative effect on the quality of phenol and acetone products;

– Significant complication in the fractionation section, caused by disposal (treatment) of “lighter” cracking products;

– Difficulties in burning of “heavy ends” formed during cracking; and

– Increase in required capital investment, elevated energy consumption, and higher operating costs.

In view of the abovementioned explanation, resear-chers in ILLA launched their persistent attempts to find effective solutions for enhancement of process selectivity at the CHP cleavage stage, proceeding from their prior in-depth research focusing on the kinetics and mechanisms of the reactions involved in a phenol process, as is noted in reference [6]. At the time when ILLA initiated their studies, the global knowledge in this domain, and in particular the then-existing notion of the chemistry of the reactions under question, was obviously insufficient to reveal the true causes of failures of previous attempts at selectivity improvement.

In accordance with the description presented in [6], a supplemented overview of the chemical conversion reactions, which occur during technical grade CHP cleavage, is presented below: –Main reaction (releases immense heat):

cumene hydroperoxide → phenol + acetone, 486 kcal kg –1, (4)

– Side reactions (primarily absorb heat): dimethylbenzyl alcohol →← α-methylstyrene + H2O, (5)

dimethylbenzyl alcohol + phenol → o-, p-cumylphenols, (6) dimethylbenzyl alcohol

→ α-methylstyrene dimers + H2O, (7) dimethylbenzyl alcohol + phenol

→ cumylphenyl ether, (8) cumene hydroperoxide + dimethylbenzyl alcohol

→ dicumylperoxide + H2O, (9)

cumylphenols, α-methylstyrene dimers + phenol → polymeric products, (11)

– Formation of minor impurities: acetone + cumene hydroperoxide

→ hydroxyacetone + dimethylbenzyl alcohol, (12)

cumene hydroperoxide dimethylbenzyl

alcohol + acetophenone etc., (10) H2SO4

2 acetone →← diacetone alcohol → mesityl oxide + H2O, (13)

hydroxyacetone + phenol → 2-methylbenzofuran. (14)



7

In reality, there are many more chemical reactions taking place that contribute to formation of minor impurities, than are indicated in above scheme. However, the most significant complications in product fractionation and phenol treatment tech-nologies are caused by hydroxyacetone, mesityl oxide, and 2-methylbenzofuran, i.e., the impurities formed in reactions (12) to (14).

In accordance with the supplemented scheme described by reactions (4) through (14), the following drawbacks and errors of the earlier chemical approaches that were relied on in implementation of the first-generation commercial technologies for acid-catalyzed CHP cleavage, as well as their further modifications, are highlighted below:

– The reactions of α-methylstyrene and dicumyl-peroxide formation were considered to be irreversible;

– All of reactions (4) through (14), above, were considered to be reactions of general acid catalysis, which are described by the function: log k = f ([H2SO4]);

– Formation of α-methylstyrene dimers was considered to be a typical reaction occurring by car-bonium ion mechanism due to protonation of the double bond of an α-methylstyrene molecule;

– The activation parameters of reactions (4) through (14), above, were not established;

– The causes for the anomalously high catalytic activity of H2SO4 in an equimolar phenol-acetone mixture, in which the reactions were carried out in a commercial process, were not investigated;

– The causes for the slowdown of the rates of many reactions listed above under the effect of water, cumene, and of other components that are always existent in the reaction medium, were not established;

– The occurrence of CHP decomposition by two reaction paths, via complexes of CHP with a certain type of acidic particles that attack different oxygen atoms of CHP’s peroxide group, was not discovered. (Moreover, it is currently known that the selectivity of CHP conversion reaction depends on the type of catalyst used (e.g., “severe” or “mild”), on its con-centration, and on the properties of the reaction medium);

– The studies of the kinetic regularities of CHP conversion and by-product formation reactions were at a very primitive level; and

– Neither the reactions of hydroxyacetone and 2-methylbenzofuran formation, nor reactions (10) and (11) were known at the time.

It would be unfair to blame the pioneers of the process for the aforementioned drawbacks and gaps in knowledge, but the indisputable fact that those drawbacks shaped the decisions made by subsequent researchers, designers, and licensors of modernized technologies, over more than four decades since the first phenol plant start-up, serves as clear evidence of their poor scientific and engineering expertise. Moreover, neither high expertise, nor great labor cost was required for a set of studies that would verify the reversible nature of the α-methylstyrene and dicumylperoxide formation reactions, and would demonstrate the absurdity, from the scientific point of view, of the expectation of high selectivity of dicumylperoxide/dimethylbenzyl alcohol conversion reactions (with simultaneous fulfillment of the requirement of a very high degree, more than 99%, of their conversion) as a result of implementation of the following “solutions:”

– one-step process design; – use of mixing reactors; – imposing “severe” operating conditions (i.e., a

higher H2SO4 concentration);

– changing the acid catalyst type, e.g. substituting H2SO4 for SO2, or for heteropolyphosphoric acids having a stronger catalytic activity;

– substituting a homogeneous acid catalyst (H2SO4) for various types of heterogeneous acid catalysts;

– adding extra water to the reaction medium; and – adding extra acetone and cumene to the reaction

medium. In addition, there was a general opinion that CHP,

with its great potential hazards, must be decomposed very rapidly and completely. Such an approach, as well as the purely chemical misconceptions mentioned above, required the one-step process design and im-position of “severe” operating conditions, including a sufficiently high concentration of sulfuric acid and a reasonably high process temperature, for avoidance of incomplete CHP decomposition (i.e., the presence of certain amounts of unreacted CHP in the reactor effluent). This was commonly assumed to be the only correct solution, both from the standpoint of process safety and for the purpose of maximum process selectivity. Indeed, bringing the process conditions into


ZAKOSHANSKY 8

a milder range (by decreasing H2SO4 concentration or process temperature, or by adding various modifiers of the reactions such as water, acetone, cumene, etc. to the reaction mixture) resulted in a marked decrease in process selectivity value and in incomplete CHP decomposition, the latter treated as an inadmissible deviation from the mandatory safety requirement.

For the reasons discussed above, researchers and designers, in their attempts to pursue process improvement, followed the erroneous principles of chemical and engineering implementation of the process, while the lack of scientific courage and, most importantly, of in-depth knowledge of the art of chem-istry and reaction kinetics, did not allow them to com-pletely abandon the outdated process designs, or at least to try to perform its comprehensive modernization.

ILLA’s researchers thoroughly examined the causes of all previous failed attempts to improve the one-step CHP cleavage process, trying to break the apparent deadlock that had stumped all of the other process designers. To accomplish its goal, ILLA completely cast away the philosophy of all aspects of other pioneer and subsequent technologies, including the previous commonly held conceptions of chemistry/kinetics of the main and side reactions, and the designs of the processes themselves. As a result, starting in 1980, and continuing its work over two decades, ILLA was able to create an essentially novel CHP cleavage process, and to implement it commercially at various phenol plants worldwide. The similarities between this process and its predecessor (and various modifications thereto), were limited only to the fact that both processes used the same feedstock (i.e., technical grade CHP), and produced the same target products (i.e., phenol, acetone, and α-methylstyrene). In summary, ILLA’s new process was based on a number of fundamentally original chemical and engineering solutions which provided, and facilitated an opportunity to achieve the maximum possible levels of process selectivity and process safety:

(1) Utilization of a two-step design (converted from a prior one-step design in 1975-80, after thorough kinetic research by the author of this article);

(2) Adopting a process design philosophy, that is essentially opposite to the previously followed concept of super-fast and 100 % complete CHP decomposition, [11–19], and that espouses the following:

– slow CHP decomposition;

– utilization of a series of reactors operating under plug-flow conditions for CHP;

– incomplete CHP decomposition (65% or less CHP conversion per pass);

– strictly defined distribution of CHP conversion over three sequential reactors, as is noted in references [11, 15, 18, 19]; and

– conversion of remaining CHP in a second step reactor system;

(3) Fundamentally changing the composition of the CHP cleavage reaction medium – using an acetone/phenol/cumene mixture with a ratio of ((1.0–1.5) : 1 : 0.2), which varies as a function of cumene content in the CHP feed;

(4) Using a newly developed method for feeding CHP into the reaction system, completely different from the conventional technique;

(5) Controlling the first step CHP conversion value, and controlling the process safety level and selectivity, by utilizing an additional reactor as a calorimeter;

(6) Configuring the second step as an adiabatic plug-flow reactor, for converting CHP remaining from first step, converting dimethylbenzyl alcohol into α-methylstyrene, and converting dicumyl peroxide, synthesized at the first step, into target products;

(7) Utilizing a second step reaction system featuring:

– A reaction mixture composition different from that at the first step; and

– Utilization of NH4HSO4 as a “mild” acid catalyst, rather than using the ”severe” H2SO4;

(8) Utilizing a computerized procedure for plant start-up, rather than doing so manually;

(9) Embedding a special three-level protection system in the process, instead of using single-level protection; and

(10) Utilizing a computerized online control system that protects against process disturbances, and that maximizes the process selectivity. For this purpose, a completely unique “guidance” system has been developed, which on its own, independently of the operator’s skills, with the aid of special software, is capable of automatically and adaptively selecting the appropriate path of safeguarding the process, while



9

optimizing the yields of desired target products.

The state-of-the-art of the CHP cleavage process invented by ILLA [11], is particularly remarkable, in that the most drastic modification of the process design, and implementation of the ten solutions listed above, relies on chemical changes of the main and side reactions carried out in reaction mixtures that have fundamentally novel compositions and properties, for both steps of the CHP cleavage process. These chemical changes resulted in the following:

(1) The side reaction leading to loss of target products is eliminated:

(6) ILLA’s process eliminates the irreversible reactions of polycondensed phenols formation, which is distinct from all other one-step and two-step technologies, where polycondensed phenols represent about 10–20 % relative of the total phenol tar (waste product).

The chemical changes described in the items 1–6 above are based on an in-depth study of the effect exerted on the kinetics, and on the mechanism of the main reaction [20] and the side reactions [21–27], by the reaction mixture composition. In fact, this study has revealed the true causes of the repeated failures of many researchers throughout the world, who have unsuccessfully tried to improve the CHP cleavage process performance. The results of this study, performed by the author of this article and described in further detail in [28–33], were as follows:

(1) The extremely fast rate of CHP decomposition is caused by the exceptionally high acidity (see Figs. 4 and 5, below), determined by the Hammett acidity function, H0 (more specifically, HS

0, where S stands for “solvent”) of the reaction medium (containing phenol, acetone, and H2SO4), as is noted in references [28–30];

(2) The CHP decomposition reaction, and most of the side reactions, are reactions of specific (rather than general) acid catalysis, and therefore they are determined by the acidity function (HS

0), rather than by H2SO4 concentration;

(3) The reaction mixture acidity value, hS0 (HS

0 = –log hS

0), can vary dozens of times in response to changes in the acetone/phenol ratio, as is noted in reference [31], or when a very small quantity of protic solvents (e.g., H2O [20, 31], alcohols, etc.), or of aprotic solvents (e.g. cumene), is added. This wide range of variability in the reaction mixture acidity value induces equally drastic alterations of the rate constant of CHP decomposition, and of other reactions occurring in the process.

(4) The following optimum composition and process conditions have been selected for both the first and the second steps of a commercial process, based on hS

0 values at variable reaction mixture composition (i.e., at variable acetone/phenol/cumene/H2SO4/H2O ratios), and on the correlation found between the temperature and hS

0 values:

– additions of different quantities of acetone to the first process step and to the second step;

Cumene hydroperoxide × dimethylbenzyl alcohol+ acetopenone;

H2SO4

(2) The new process achieves almost quantitative synthesis of dicumylperoxide at the first step, which forces this reversible reaction of the first step to proceed in an essentially irreversible manner:

CHP + dimethylbenzyl alcohol → dicumylperoxide + H2O,

to prevent dimethylbenzyl alcohol conversion into by-products;

(3) Reversible reaction of the first step dimethylbenzyl alcohol →← α-methylstyrene + H2O

is shifted to dimethylbenzyl alcohol ;

(4) Irreversible dimethylbenzyl alcohol conversion into by-products (D), such as α-methylstyrene dimers and cumylphenols:

2 dimethylbenzyl alcohol → D1 + D2 + D3 + H2O,

dimethylbenzyl alcohol + phenol → o-, p-cumylphenols

is almost eliminated at the first step, and is then minimized at the second step to a great enough extent, to enable ILLA’s process to demonstrate a 7–10 times lower yield of by-products, as compared to any one-step technology;

(5) In spite of appreciably greater acetone concentration in the reaction medium, the acetone to mesityl oxide reaction is almost eliminated, reducing the mesityl oxide quantity by a factor of about 10, or even of about 20 times, as compared to any one-step technologies, and by a factor of two or three times, as compared to any later-appearing competitive counterparts of ILLA’s two-step process; and


ZAKOSHANSKY 10

– increase in the cumene content;

– additions of different quantities of water to the first step and to the second step;

– optimum H2SO4 concentration achieved and maintained at the first step, and the use of NH4HSO4 as a “mild” acid catalyst at the second step, instead of H2SO4; and

– lowered temperature at the first step, ensuring a strictly determined and safe value of CHP conversion into dicumylperoxide and phenol and acetone, along with a higher second step temperature which, in combination with use of the “mild” acid catalyst (NH4HSO4), and increased content of acetone and cumene, leads to high selectivity of conversion of dicumylperoxide and dimethylbenzyl alcohol into target products.

The experimental analysis, disclosed in [20], showed that the addition of acetone drastically decreases both the h0 value and the rate constant of CHP decomposition (see Figs. 4 and 5). Even minor additions of water (about 0.1–1.0 wt %) to the phenol-acetone medium reduce the h0 value by almost two orders of magnitude, as is noted in [20].

Therefore, due to an increase in H2O concentration, the equilibrium shifts to the right [20]:

activity, compared to most of the other acid particles involved.

A similar pattern is observed for the rate constant of CHP decomposition under the influence of extra acetone: the reaction rate constant decreases about 2 to 4 fold (see Fig.4), as is noted in [20].

Unlike acetone and water, cumene is not a “reagent” in reaction (15), and thus cannot shift its equilibrium. However, an increase in cumene con-centration by about 1 % (absolute) in a phenol-acetone medium, has been found to reduce the rate constant of CHP decomposition by about 27 % (relative). Consequently, this effect is about three times weaker than the influence of a similar quantity of acetone on kCHP (see Fig.6, below). For commercial processes, however, this effect on the process rate is immense, because the stability of CHP conversion is the key condition for the safety of this technology. Such a strong dependence is explained by the so-called effect of “salting out water” by cumene, i.e., the dis-placement of water from its associates with phenol by cumene. In accordance with the equilibrium of reaction (15), the displaced water acts on the acid catalyst, converting a non-dissociated H2SO4 and quasi-ionic pairs HOSO3

...H...O═C(CH3)2 into a catalytically inactive (weak) species H5O2

+ and, ultimately, reducing the CHP decomposition rate constant (see Fig. 6). This is also proven by the measurement of h0 value, which actually falls in proportion to kCHP.

In connection with the discovered change in the contents of acidic particles in the phenol-acetone medium, the temperature dependence of CHP decomposition at a variable H2O content of about 0.2–

Fig. 4. Cumylhydroperoxide decomposition rate constant vs. phenol/acetone mole ratio [H2SO4] = 0.03 wt %; [H2O] = 0.8 wt %. [Cumene], wt %: (1) 2 and (2) 12.

Fig. 5. Acidity vs. water concentration in equimolar phenol–acetone solution at T = 25°C. [H2SO4], wt %: (1) 0.002, (2) 0.020, and (3) 0.030.

HOSO3...H...O=C(CH3)2 + 2H2O

→← H5O+2 + HSO–

4 + (CH3)2C=O. (15)

At a water to acid mole ratio of about 2 : 1, the equilibrium of reaction (15) noticeably shifts towards species H5O+

2, also causing a slowdown of the reaction rate, because these species have a very low catalytic



11

0.8 wt % and a variable acetone to phenol mole ratio of about 1 : 1 to 1.5 : 1 was investigated. The research demonstrated a noticeable change in the activation parameters in both cases. The discovered increase in the activation energy of CHP decomposition from about 18 to 21 kcal mol–1 supplies additional evidence (along with h0 and kCHP) of a drastic change in the composition of acidic particles and, consequently, of a change in the mechanism of CHP decomposition at minor fluctuations in the water concentration in the phenol-acetone medium.

Table 1 presents the rate constants and activation parameters for reversible conversions of dimethylbenzyl alcohol and formation of ortho-, para-cumylphenols and α-methylstyrene dimers (Di), with an assumption of constant h0 value, equimolar acetone to phenol ratio in reaction medium, and variable water concentration (from about 0.4 wt % to 1.0 wt %). However, any change in the aforementioned types of acidic species due to variations in acetone/phenol ratio or water concentration would have a profound impact on the h0 value and the values of activation parameters, Ea and log A, which can result in gross errors in evaluation of the reaction rate constants, unless the data shown in Table 1 is properly adjusted.

A low Ea value for a dimethylbenzyl alcohol to α-methylstyrene conversion reaction, as compared to the reverse reaction (α-methylstyrene to dimethylbenzyl alcohol), confirms a remarkably greater reactivity of a dimethylbenzyl alcohol molecule than that of α-methylstyrene, and therefore proves that a dimethyl-benzyl alcohol molecule is in fact responsible for formation of α-methylstyrene dimers and cumyl-phenols.

An increase in the acetone to phenol mole ratio in the reaction medium from about 1 : 1 to 1.5 : 1, dramatically reduces the rate constants of Di and cumylphenols formation. Therefore, the operation of

phenol process in an acetone-excessive mixture will decrease the yield of undesirable by-products, Di and cumylphenols. At the same time, however, an increased (over about 1 : 1) acetone to phenol mole ratio in the reaction medium will greatly decrease the rate constant of CHP cleavage, resulting in a lower degree of CHP conversion, and an intolerable, in terms of process safety, increase in CHP concentra-tion in the reactor effluent. In fact, without establishing a very rapid-responding computer-aided control over the degree of CHP conversion, raising the acetone to phenol mole ratio above 1, in an attempt to reduce the yields of Di and cumylphenols, and/or to improve the yield of α-methylstyrene in a one- or two-step phenol process, is not only dangerous, but simply impermissible. Moreover, even in commercial processes with rapid-response computer-aided controls, configured to ensure that the degree of CHP conversion is strictly constant [11], the acetone to phenol mole ratio in the reaction medium cannot be varied arbitrarily, just to preclude

Fig. 6. Cumene hydroperoxide decomposition rate constant vs. concentrations of cumene and water in phenol–acetone reaction mixture. [H2SO4] = 0.03 wt %; T = 55°C; acetone/phenol = 1.16 mol; [Cumene], wt %: (1) 2; (2) 14; and (3) 28.

Reaction Rate constant

log A, min–1 b Ea, kcal mol–1 b min–1 mol kg–1 min–1

dimethylbenzyl alcohol → α-methylstyrene 0.47 5.9–8.2 8.4–10.7

α-methylstyrene → dimethylbenzyl alcohol 0.094 8.8–9.2c 12.6–13.9

dimethylbenzyl alcohol → cumylphenols 0.023a 14.5–19.2 15.7–24.7

dimethylbenzyl alcohol → Di 0.027a 13.6–17.4 13.7–17.4 a Average value for total cumylphenols isomers, and for total Di isomers, respectively. b Higher water concentration increases the activation parameters for reactions. c A, mol kg–1 min–1.

Table 1. Kinetic parameters of by-product conversion reactions


ZAKOSHANSKY 12

the production of Di and cumylphenols, and to thus favor the α-methylstyrene yield.

For the above reason, the statement by Marshall Jr. B.K. et al. in [34] that the CHP concentration at the reactor outlet decreases, when extra acetone is added to the reactor, is clearly nonsensical, from both scientific and engineering standpoints. This position, with regard to the statements by the above-noted “expert”, is confirmed both by practical commercial processes, as well as by results of research on the acidity value h0 (see Fig.7), and on the kinetics of CHP cleavage, dicumylperoxide hydrolysis, and formation of Di and cumylphenols, either in an equimolar phenol-acetone mixture, or with a molar excess of acetone (see Table 2).

A significant decrease in the rate constant values in Table 2 is explained by the variation in the composition of acidic particles (non-dissociated

H2SO4, quasi-ionic pair of acetone with H2SO4, H3O+, or H5O+

2), with an increase in acetone concentration in the reaction medium. These particles possess the substantially different catalytic activities, and this difference is responsible for the changes in the h0 value (see Fig.7), as extra acetone is added to the reaction medium. However, water has a far more significant impact on the h0 value. Addition of as much as about 0.1 wt % water dramatically decreases the h0 value, thus abruptly retarding all relevant reactions. Therefore, formation of α-methylstyrene dimers and cumylphenols is affected not only by H3O+ species, but also by non-dissociated H2SO4, pseudo-ionic pair (HSO4

...H...Acetone), and H5O+

2, which, in particular, accounts for the variable relationship between the isomers of α-methylstyrene dimers, as is noted in [6].

For the first step of CHP cleavage, under conditions that prevent dicumylperoxide hydrolysis and that simulate the first step of a commercial CHP cleavage process, the rate of CHP conversion into phenol and acetone was found to be about 30 times faster than that of dicumylperoxide formation. As a result, the degree of dimethylbenzyl alcohol to dicumylperoxide conver-sion is about 5% relat., while the dicumylperoxide concentration at the outlet of CHP cleavage reactors is affected by the process parameters, such as tempera-ture, concentrations of H2SO4, H2O, phenol, acetone, and cumene, and the circulation ratio. At the second step of CHP cleavage, hydrolysis of dicumylperoxide [see scheme (16)] is essentially irreversible, due to the absence of CHP in the reaction products, as is noted in [6].

Fig. 7. H2SO4 acidity (h0) as a function of extra acetone addition to an equimolar phenol-acetone medium. [H2SO4], [H2O], [Cumene] = const; T = const.

Extra acetone, % relat. per 1 kg of equimolar

phenol–acetone mixture

k × 102

KCHP, s–1 Kdicumylperoxide, mol kg–1 min–1 KDi, min–1 Kcumylphenols, min–1

0 21 20 2.3 2.7

5 14 13 – –

10 9.5 10 1.4 1.8

15 7.3 7.5 – –

20 6.1 6.0 0.7 0.9

Table 2. Kinetic regularities of reactions of cumyl hydroperoxide cleavage, dicumylperoxide hydrolysis, and formation of α-methylstyrene dimers and cumylphenols in a phenol–acetone medium

H+, H2ODicumylperoxide phenol + acetone

+ (α-methylstyrene dimethylbenzyl alcohol).H+, H2O

(16)



13

Experimental data on hydrolytic dicumylperoxide conversion can be sufficiently described by a first order equation. The correlation between the experimental data and the approximation thereof under different conditions (temperature, phenol concentration in solvent, water concentration) is shown in Fig. 8, where the dependence of relative dicumylperoxide concentration (C/C0) on nondimen-sional contact time is graphically illustrated.

The correlation between the rate constant of di-cumylperoxide hydrolysis and the catalyst composi-tion/concentration (at a water concentration in the solvent of about 0.585 wt %) is shown in Fig. 9. This correlation is described by equation (I):

Kdicumylperoxide = xk0, (I)

where x = 33 ([H2SO4] + 0.0881 [NH4HSO4]) is an effective concentration of catalyst, in H2S04 equi-valent, in wt %; k0 is a rate constant at specific values of T, [H2O], and [Phenol], and at [H2S04] = 0.03 wt %, in min–1.

Despite a seemingly simple description of the dicumylperoxide conversion rate, various factors affect this rate in a complex manner.

For example, a change in [dicumylperoxide]0 from about 2 wt % to 6 wt % reduces the kdicumylperoxide value in an equimolar phenol-acetone mixture by about 2.5 times. A similar occurrence can be observed when water concentration in the reaction mixture rises. In both cases, a significant change in the environment

acidity, h0 is largely responsible for reducing the hydrolysis rate.

The rate constant of dicumylperoxide hydrolysis can be determined numerically at different tem-peratures and at different compositions of the solvent, using formal approximation as follows:

Fig. 8. Estimated and experimental data on relative rate of dicumylperoxide hydrolysis vs. nondimensional contact time.

Fig. 9. Dicumylperoxide hydrolysis rate constant vs. effective concentration of catalyst [x in equation (I)] at T = 60°C: (1) 0.0542 wt % H2SO4; (2) 0.0375 wt % H2SO4; (3) 0.0200 wt % H2SO4; (4) 0.0132 wt % H2SO4 + 0.0184 wt % NH4HSO4; and (5) 0.0357 wt % NH4HSO4.

(II)

where [H2O], [H2SO4], [PhOH] are concentrations of water, acid, and phenol, respectively, in wt %; kdicumylperoxide is expressed in min–1; and T is expressed in K.

However, great care must be exercised in direct utilization of a rate constant, that has been estimated by approximation (II), for calculating the size of dicumylperoxide conversion reactor. While the approximation itself is fairly accurate [mean error margin, δ (ln k) equals about 0.15 min–1], the active-tion parameters significantly depend on the com-position of the reaction mixture. With an increase in water concentration from about 0.6 to 2.0 wt %, the activation energy (Ea) of the reaction grows from about 19.5 to 24.5 kcal mol–1 (see Fig. 10). This growth is readily explained by a varied composition of acidic species catalyzing the reaction (H3O+, H5O+

2, H2SO4...S,

where S is solvent), with the function Ea = f([H2O]) being of a linear nature (see Fig.10). It should also be noted that the correlation between the rate constant of

ln kdicumylperoxide = 18.935 − 9650T

− 1.259[H2O] + 16.639[H2SO4] + 0.162[PhOH],

Kdi

cum

ylpe

roxi

de, m

in–1


ZAKOSHANSKY 14

dicumylperoxide hydrolysis and the solvent composition is quite complicated (see Fig. 11).

With a large number of side reactions occurring during dicumylperoxide hydrolysis, the selectivity of dicumylperoxide conversion is affected by many factors:

– type of acid catalyst;

– composition of reaction medium, evaluated as an acetone to phenol to cumene mole ratio;

– temperature;

– water concentration; and

– degree of dicumylperoxide conversion.

As the composition of the reaction medium varies, the rate constants of dicumylperoxide hydrolysis and by-product formation also change in consistency with acidity H0, according to the Hammett equation:

ki = Ci × 10–H0 = Ci

h0, (III)

where H0 = the Hammett acidity function; h0 = acidity of reaction medium.

The h0 value is a complex function of several variables, complicating the computation of kinetic constants of CHP hydrolysis rate.

The effective value of acidity (h0) is determined by the following factors:

– concentration and type of acid catalyst; and

– concentrations of cumene, acetone, water, and dimethylbenzyl alcohol.

The variation of h0 value, as a function of the parameters listed above, has been discussed in detail by the author [6, 31, 35–37], and was assumed as a basis of dicumylperoxide conversion technologies operated within a CHP cleavage process on a commercial scale [11–14, 19, 32, 38–39]. The effect of all these parameters explains the complex function, ln kdicumylperoxide = f ([Phenol]), indicated in Fig. 11.

In spite of the variety of parameters affecting the selectivity of dicumylperoxide conversion, certain conclusions can be drawn based on the research reported in [11–14, 19, 32, 38–39], that has been conducted in a phenol–acetone–cumene environment:

(1) Reaction mixture having an excess quantity of acetone and cumene leads to a higher selectivity;

(2) Equimolar acetone to phenol ratio precludes achievement of high selectivity of dicumylperoxide conversion;

(3) Use of strong Brønsted acid catalysts, like H2SO4 etc., appreciably reduces the process selectivity;

(4) Mild acid catalysts, such as catalytic complex of NH4HSO4 and acetone, provide a higher selectivity;

(5) Temperature elevation generally favors selectivity, although the result may in fact be opposite when a strong acid catalyst, such as H2SO4, is used;

(6) Raising the dicumylperoxide conversion above a certain limit will predictably decrease selectivity.

Although the general principles for improvement of dicumylperoxide conversion selectivity listed in items (1) through (6) above are essentially correct, the

Fig. 10. Activation energy of dicumylperoxide hydrolysis vs. water concentration in the reaction mixture.

Fig. 11. Logarithm of dicumylperoxide hydrolysis rate constant vs. concentrations of water and phenol in the reaction mixture. T = 70°C; [H2SO4] = 0.03 wt %. Curves 1 through 7 correspond to variable [H2O] concentrations ranging between 0.2 wt % and 1.55 wt %, respectively.



15

maximum potential value of the selectivity, evaluated as a desired by-product α-methylstyrene yield of about 93 mol %, at a dicumylperoxide conversion rate of about 99 % [11–14, 38–39], cannot be achieved in commercial practice, unless a specific advantageous combination of factors (1) through (6) above is strictly observed. For instance, use of hyperpolyphosphoric acid, instead of H2SO4, leads to the formation of various by-products. In an attempt to arrange isothermal conversion of dicumylperoxide in equimolar phenol-acetone mixture with a H2SO4 catalyst, where acidity h0 was controlled by the H2SO4 concentration, the designers predictably failed to achieve the selectivity claimed, as is noted in references [40–43], due to a number of errors in application of both chemistry and process engineering. The same is also correct for the cases of unskilled addition of acetone to the reaction mixture [44, 45]. In summary, any deviations from the parameters and values required by the kinetics and by the mechanism of dicumylperoxide hydrolysis and by-product formation, deteriorate selectivity, leading to a result that is opposite to the objective being pursued.

In commercial practice of acid-catalyzed CHP cleavage, in a phenol-acetone environment, a number of side reactions occur, including the formation of minor impurities like 4-methyl-3-pentene-2-on (mesityl oxide), diacetone alcohol, hydroxyacetone, and 2-methylbenzofuran. While their formation does not have a substantial effect on the selectivity of the CHP cleavage stage, it is in fact of critical importance for the overall selectivity and energy capacity of an entire phenol process, as well as for the quality of the desired target products.

The most effective description, among various models of diacetone alcohol and mesityl oxide formation, verified by a good correlation between the calculations and the corresponding experiment, was determined by a scheme of two sequential non-reversible reactions of the first order:

where [Acetone]0 is the initial acetone concentration, wt %; and τ is time, min.

The temperature functions of rate constants at an acetone to phenol mole ratio of about 1.5 : 1 appear below:

ln k1 = (8.1 ± 0.5) – (12800 ± 200)/RT,

ln k2 = (28.4 ± 2.2) – (22000 ± 1500)/RT. (V)

The study demonstrated that the rate constant of diacetone alcohol dehydration is about three orders of magnitude higher than the rate constant of formation of this alcohol. The study also showed that elevating temperature from about 55°C to 100°C, results in approximately a 70-fold increase in k2 value, while the value of k1 increases by as much as approximately 10-fold.

As was mentioned above, sulfuric acid, when introduced into a phenol-acetone solvent, demon-strates an exceptionally high acidity, which would seem to anticipate a high rate of diacetone alcohol and mesityl oxide formation. However, a significant part of acetone molecules forms associates with phenol molecules, as is noted in [32]. As a result, acetone conversion into final product was about 0.3 rel % over about 30–40 minutes even at high temperatures of about 90–100°C. Increasing the acetone percentage in the solvent not only failed to increase mesityl oxide accumulation, but on the contrary negatively impacted formation of mesityl oxide, primarily due to weakened catalytic properties of H2SO4 (Table 3).

The analysis of Table 3 demonstrates that, within the studied range of acetone concentrations, the function ln ki = f (H0) (for both k1 and k2) is linear, and the sum ln ki + (H0) remains substantially constant. Therefore, the reaction comprises specific acidic catalysis. The mesityl oxide formation rate increases in proportion to H2SO4 concentration (and correspon-dingly to the H0 value), as shown in Fig. 12. Moreover, the following empiric correlations are true for equi-molar acetone to phenol ratio, at a temperature of about 75°C and H2SO4 concentration ranging between about 0.03 wt % and 0.06 wt %:

ln k1 = 0.875 log [H2SO4] – 3.18, (VI)

ln k2 = 1.007 log [H2SO4]. (VII)

where k1 and k2 are measured in min–1, and [H2S04] in wt %.

2Acetone diacetone alcoholk2

k1

mesityl oxide + H2O. (17)

The rate constants, k1 and k2, were evaluated by minimizing the sum of squared deviations between calculated and experimental values of mesityl oxide concentrations:

(IV) [mesityl oxide] =k1

k2[Acetone]0(k2τ − 1 + e−k2τ ),


ZAKOSHANSKY 16

As was anticipated by prior research directed to studying the effect of water concentration on acidity value (h0) in the solvent in question, an increase in water concentration from about 0.71 wt % to 1.07 wt % reduced the k1 value about 1.5 times, and also reduced the k2 value about 3 times.

Based on the study of the kinetics and mechanisms of reactions occurring in the process, a number of methods for minimization of the quantity of formed mesityl oxide were developed and further imple-mented in ILLA’s process, which resulted in reduction in the quantities of mesityl oxide by a factor of 6 to 10, as compared to the values achieved in other two-step CHP cleavage technologies.

Special attention should also be paid to the problem of hydroxyacetone, which is a very undesirable cont-aminant that is formed during CHP cleavage. Although hydroxyacetone is typically formed in a very small quantity of about 0.2 wt %, with respect to the total amount of CHP cleavage products, this contaminant is a source of many concerns in phenol process, including, but not limited to:

– significant deterioration of the phenol product (poor color, an unacceptably high content of 2-methyl benzofuran, etc.);

– dramatic escalation in the consumption of various utilities for the process;

– increase in alkali consumption; – poisoning of the catalyst used for phenol treat-

ment; – poisoning of the catalyst used for α-methylstyrene

hydrogenation; – required growth in capital investment; and – a marked increase in the quantity of waste water

exiting the process. Despite the wide variety of ways in which

hydroxyacetone and its derivatives negatively impact the process performance, the reactions of its formation and conversions have remained outside the focus of global research, over the entire period of existence of phenol processes. In commercial practice, searches for solutions were conducted by way of a “trial-and-error” method, and were invariably intended for fighting the negative effects thereof (e.g., the elevated content of 2-methylbenzofuran), rather than addressing the root cause (i.e., the presence of hydroxyacetone).

Figures 13 and 14, show that hydroxyacetone formation at the first step, to a large extent, depends on the values of acid concentration and of temperature. The practical conclusion that may be drawn from the demonstrated effect of acid concentration, is that a one-step homogeneous CHP cleavage process, with its unavoidably severe conditions, yields about 2000 ppm of hydroxyacetone, a magnitude nearly two times as large as that for mild conditions, imposed at the first step of a two-step process. Of foremost significance, however, is the theoretical aspect of this data, with regard to the mechanism of hydroxyacetone formation. In particular, the study results have verified the following:

Table 3. Correlation between the rate constants of diacetone alcohol and mesityl oxide formation and the solvent composition (T = 85°C; [H2SO4] = 0.03 wt %; [H2O] = 0.9 wt %)

Acetone/phenol mole ratio H0 k1 × 105, min–1 k2 × 102, min–1 H0 + log k1 H0 + log k2

1 : 1 –0.11 5.50 5.84 0.63 0.66

1.5 : 1 0.0094 5.74 4.50 0.77 0.66

1.8 : 1 0.0556 4.30 4.62 0.69 0.72

2.05 : 1 0.0581 3.43 3.18 0.59 0.65

Fig. 12. Logarithm of diacetone alcohol dehydration rate constant (k2) vs. acidity function (H0) T = 75°C; acetone/phenol = 1 : 1 (mol).



17

– the fact that the reaction occurs by the way of an acidic mechanism, rather than through radical formation; and

– the non-linear trend of hydroxyacetone formation rate, illustrated in Fig.13, proving that the reaction follows specific acidic catalysis, log khydroxyacetone = f (h0), rather than general acidic catalysis, where log khydroxyacetone is a linear function of H2SO4 concentration.

Hydroxyacetone accumulation at the second step is by an order of magnitude slower than that at the first step (see Figs. 15 and 16).

Such a seemingly contradictory trend of hydroxy-acetone accumulation: fast at the first step of the process, but slow at the second step – is actually typical of the kinetics of many chemical reactions that occur through intermediates which limit the reaction rate [see scheme (18) and alternative scheme (19)]:

Mathematical processing of experimental data has produced the following empirical formula for calculation of hydroxyacetone concentration in commercial practice of a two-step homogeneous CHP cleavage process:

Fig. 13. Hydroxyacetone content in the CHP cleavage product (following the first step of cleavage system) as a function of sulfuric acid concentration: [hydroxyacetone] = f ([H2SO4]). T = 50°C; [Acetone]excess = 10 wt % per 1 kg of equimolar acetone–phenol mixture.

Fig. 14. Hydroxyacetone content in the CHP cleavage product (following the first step of cleavage system) as a function of process temperature: [hydroxyacetone] = f (T). [H2SO4] = 0.03 wt %; [Acetone]excess = 10 wt %.

Acetone + CHPfast, k1

[X]fast, k2 Hydroxyacetone

slow, k3

2,2-bis-cumylperoxypropane

Acetone + CHPfast, k1

Hydroxyacetone

slow, k2

[X]

slow, k3

(18)

(19)

where CHydroxyacetone, CAcetone, and CAcid are the concentrations of hydroxyacetone, acetone, and sulfuric acid, respectively, in mol l–1 ; k1 and k2 are the effective constants of hydroxyacetone formation from 2-hydroxy-2-cumylperoxypropane and 2,2-bis-cumyl-peroxypropane, respectively; and n is the circulation ratio of CHP cleavage product.

In Eq. (VIII), the power members do not refer to the order of reaction. In addition, the equation itself should be considered an approximation equation, usable in engineering design for predicting the amount of hydroxyacetone formation, based on specific process conditions, with a practically sufficient accuracy of about 14 % relat. However, finding an effective solution for removal of hydroxyacetone from CHP cleavage products is probably a goal of even greater importance.

Hydroxyacetone, as a carbonyl compound, is capable of oxidation by atmospheric oxygen to form carboxylic acids and, at elevated temperatures, carbon dioxide as is noted in [46]. Phenol’s inhibiting effect on the occurrence of the hyd-roxyacetone oxidation reaction can be suppressed with sodium hydroxide. In this case, oxidative conversions of hydroxyacetone and products of its condensation in aqueous environment

(VIII) CHydroxyacetone = 2685(k1CAcetoneCAcid + k2CAcid )/n,4.9 0.3 −0.2

[X] is 2-hydroxy-2-cumylperoxypropane.


ZAKOSHANSKY 18

must lead to addition of atmospheric oxygen in alkaline environment, with formation of sodium salts of carboxylic acids, such as formic and acetic [25–26, 47–49]. Sodium pyruvate is also assumed to be formed in accordance with the scheme (20), as is noted in [46]:

Oxidation of hydroxyacetone, unlike its alkali-

Elimination of hydroxyacetone formed in the course of CHP cleavage reactions is a necessary step, intended to prevent formation of 2-methylbenzofuran, which otherwise inevitably occurs at a downstream stage of phenol treatment with the use of acid catalysts, such as IER or zeolites, in the following reaction:

Fig. 15. Hydroxyacetone content in the CHP cleavage product (following the second step of cleavage system) as a function of residence time: [hydroxyacetone] = f (τ). T = 100 °C; [H2SO4], wt %: (1) 0.015 and (2) 0.0075.

Fig. 16. Hydroxyacetone accumulation at the first and the second cleavage steps. T = 50°C; [H2SO4] = 0.03 wt %; (Step I): T = 50°C; [H2SO4] = 0.03 wt %; [Acetone]excess = 10 wt %; and (Step II): T = 100 °C; [H2SO4] = 0.015 wt %.

CH3−C−CH2OH

O

O2 + NaOHCH3−C−COONa.

O

(20)

aided condensation, is a non-reversible reaction result-ing in exhaustive hydroxyacetone conversion. The reaction rate is markedly faster when air is injected to the reactor (see Fig. 17).

Pressurizing was found to actually accelerate the conversion of hydroxyacetone. The correlation between the reaction rate and pressure is graphically illustrated in Fig. 18.

The kinetics of this process can be described as: W = keffChydroxyacetone, (IX)

where keff is effective rate constant, h–1; and Chydroxyacetone is hydroxyacetone concentration, mol l–1.

The effective rate constant keff is in the following correlation with NaOH concentration and air pressure:

keff = k1CNaOHP0.5, (X)

where k1 is a constant assuming a temperature dependence of reaction rate.

The temperature dependence of the reaction rate is described by the following values:

ln A = 17.8; Ea = 10.5 kcal mol–1.

Hydroxyacetone + phenol

2-methylbenzofuran.H+

(21)

Removal of 2-methylbenzofuran from phenol using the abovementioned acidic catalysts constitutes an extremely difficult challenge, with the assumption of the general view of 2-methylbenzofuran conversion into products of deep condensation illustrated by scheme (22), due to low reactivity of 2-methyl-benzofuran.

Hydroxyacetone 2-methylbenzofuranH+

H+

Products of deep condensation. (22)

Thorough research performed by ILLA revealed that the problems of IER-aided phenol purification must be attributed not so much to IER properties themselves, but more to the erroneous approach relating to the use of acidic catalysts, that has been universally applied by all process designers for almost 60 years, and which is unfortunately still advocated by most of them. In fact, the catalyst of choice should be of the basic type. Exactly the same pattern of chemistry-related mistakes by designers of phenol purification technologies has been observed for quite some time, and unfortunately continues to repeat itself at present, in relation to the application of an acid-catalytic treatment method for removal of mesityl oxide and aldehydes from phenol.



19

Having taken into account the abovementioned mistakes attributed to other technologies, ILLA’s developers of an innovative approach to using phenol as a reaction medium chose an essentially different chemical approach to the phenol purification problem, which comprises, at least in part:

(a) completely or substantially preventing contact of hydroxyacetone, aldehydes, and mesityl oxide with an acidic catalyst (such as an IER or others), by using a so-called unique “hydroxyacetoneC Process,” developed by ILLA, in which chemical reactions of the abovementioned impurities are conducted through an oxidative method with an alkaline catalyst [25–26,48]; or

(b) arranging a first treatment step, where certain impurities, including hydroxyacetone, aldehydes, and mesityl oxide, are converted with an essentially different type of catalyst, specifically the redox type [49], which, contrary to an acidic catalyst, promotes occurrence of the subject reactions in a smooth manner, and with a deep level of conversion [49]; and a sequential second treatment step, where reactions requiring an acidic type of catalyst (such as an IER, etc.) are conducted [50–51]. With regard to catalyst selection for the second treatment step, it should be considered that a Zeolite catalyst has a longer lifetime of at least about 7 years between regenerations, as compared to about 1.0 to 1.5 years for an IER.

The proposed innovative approach has provided an advantageous solution for obtaining a high grade phenol product, and eliminated a number of issues referring to certain impurities, which could not be removed under the framework of the previously known approaches for phenol purification.

The analysis of the data presented above, demon-strates the high degree of difficulty in developing an optimal chemical implementation of CHP, dicumyl-peroxide, dimethylbenzyl alcohol, hydroxy-acetone, and aldehyde conversion reactions that would serve the purpose of minimizing the yield of by-products and that would simultaneously meet the rigorous process safety requirements.

The only tangible criterion for estimation of the true level of process performance, is provision of relevant “real world” figures and facts. In this context, a comparative Table 4, summarizes the main charac-teristics and parameters of different two-step processes which have replaced the original pioneer technologies over the period of 1979–2009, and are currently operated at various commercial CHP cleavage units throughout the world.

It should be noted that the numerous attempts to implement the so-called “light” modernization of CHP cleavage process units [40, 46, 48, 53–54], have all proven to be unsuccessful. In reality, they were performed by a substantially “blind” copying and/or plagiarism of certain engineering solutions used by ILLA in the development of its breakthrough technology [11]. This technology has effectively achieved a number of advantageous results, including, but not limited to:

– an α-methylstyrene yield of more than 90 mol %;

– a non-disposable waste yield of about 25–30 kg t–1 of phenol;

– the minimized yield of certain impurities having a negative effect on the quality of desired products;

Fig. 17. Kinetic curves of hydroxyacetone expenditure in inert vs. air anvironment under atmospheric pressure: (■) argon and (○) air.

Fig. 18. Kinetic curves of hydroxyacetone expenditure under variable air pressure. T = 80 °C; [NaOH] = 0.3 wt %. Pressure, kg cm–2: 1 (Δ) 3.2; 2 (□) 6.3; 3 (◊) 9.7.


ZAKOSHANSKY 20

– successful implementation of a three-level automated process protection system and a computer-aided control of the process.

At present, this top-of-the-line technology is utilized as a basis for production of about 3 million tons of phenol per year worldwide, or approximately 30% of the world’s phenol capacities from plants that have been constructed and put on-stream for sixty years, since 1949. All of the other phenol/acetone plants operate either process technologies invented thirty or even sixty years ago, or somewhat modernized technologies without any serious im-provement in their process selectivity, or stop-gap (or even misappropriated) technologies (for grass-roots projects) “created” by incorporation of certain borrowed High-Tech elements into obsolete techno-logies. In terms of process selectivity, such “modernized” process plants are far from the requirements of the 21st century, while in terms of process safety, they are even inferior to the first generation technologies created by the pioneers.

With regard to other stages of a typical commercial phenol process, their chemistry is of minor importance,

at least with respect to the selectivity of chemical reactions involved therein. Certain process stages do not use innovative technologies, or at least their engineering implementation is of more significance, as compared to their chemistry, while the engineering aspects go beyond the subject matter of this review. All of these process stages, as well as certain alternative technologies and approaches, from cumene oxidation to recovery of desired products, are discussed and compared in detail in the treatise presented in [6].

The actual selectivity value of about 97 mol % achieved in ILLA’s phenol process, is close to the theoretical limit within the scope of the existing chemical approach. Taking into consideration the exceptionally complex chemistry of reactions and, simultaneously, the high potential danger relating to handling cumene hydroperoxide, the selectivity of about 97 mol % is a truly unique and astonishing achievement for large capacity petrochemical plants. The chemical approach discussed above, has certainly led to a great breakthrough, not only from the standpoint of selectivity value achieved in practice, but

Table 4. Main characteristics and parameters of different two-step CHP cleavage processes

Process characteristics ”Boiling”

(Kellogg, Mitsui, Shell, Sunoco/UOP)

Homogenous (Sunoco/UOP) Homogenous (ILLA)

Step I (H2SO4, ppm) 450–700 100–200 150–180

Step II (H2SO4, ppm) 450–700 100–200 NH4HSO4

Reaction medium, acetone to phenol mole ratio 1.05 : 1 1 : 1 1.5 : 1

Computerized process start-up Essentially impossible No Implemented at all relevant

plants Computerized monitoring/control Essentially

impossible No, or difficult to implementa

Implemented at all relevant plantsb

α-Methylstyrene yield theoretically possible, mol %a 74 80 93

Actual α-methylstyrene yield, mol %a About 65 67–74b 89–92.5c

Phenol tar yield, kg ton–1 phenola 90 70 20–30

[Hydroxyacetone], ppm 1800–2000 1500–1700 1300

[Mesityl oxide], ppm 500 300–200 < 50 a This data is either taken from public sources, or obtained by ILLA during its studies of operating plants, or from the results of ILLA’s kinetic research, or from the results of process simulation at ILLA’s pilot units. b In their advertising materials, Sunoco/UOP report an α-methylstyrene yield of about 85 mol %, as is noted in reference [52]; however, the name and capacity of the plant where this result was allegedly “obtained,” are kept undisclosed. It is possible that such a result might have been achieved at a pilot unit, otherwise it would have been known to at least a number of the other phenol producers. c An α-methylstyrene yield of about 90– 92.5 mol %, achieved by ILLA’s process under commercial conditions, has been obtained at the following plants, with the respective capacities as indicated: (GE) about 350 kt year–1, (INEOS) two 200 kt year–1 units, (FCFC) two process units with total capacity of about 400 kt year–1, (FENOQUIMIA) 42 kt year–1, and (BOREALIS) about 200 kt year–1.



21

also prima facie as an essentially inventive technology. On the other hand, the achievement of such a high magnitude of selectivity proves that its further improvement within the scope of this chemical approach, if theoretically possible, can only be reached at the expense of compromised economics. Therefore, implementation of another breakthrough requires fundamentally innovative chemical and engineering approaches, which would be able to provide simultaneous further increases in selectivity values, simplification of the entire phenol process, and an even higher level of process safety.

Such an innovative chemical/engineering approach may be based on two alternative philosophies, substantially different from one another, which were both postulated by ILLA’s experts:

(1) Increasing the selectivity value of the cumene oxidation stage to nearly 100 mol %;

(2) Separating CHP from by-products of cumene oxidation, such as dimethylbenzyl alcohol, aceto-phenone, dicumylperoxide, and aldehydes, as is noted in [55], which would nearly automatically provide a 100% selectivity of the CHP cleavage stage.

Implementation of either of the two alternative approaches listed above, can theoretically result in (1) an increase in the selectivity value of the entire phenol process, up to about 99–99.5 mol %, in (2) substantial simplification of the overall process design, and in (3) significant improvement of process safety. In addition, utilization of the first approach would also lead to significant savings in steam consumption. However, the selectivity improvement in both cases would result from essential simplification of the process chemistry:

Cumene → CHP → phenol + acetone. (23)

It should be noted that the first of the above-listed new-generation approaches has not yet been developed into more than a hypothetical conception, although any theoretical restrictions for achievement of the cumene oxidation selectivity of nearly 100 mol % have now been eliminated.

The second option has been used as a basis for development of a so-called patented “Wasteless Phenol/Acetone Production Process” (WEPP). Upon completion of laboratory studies and tests, this process was subjected to a lengthy pilot unit testing, which was performed over a period of about 1.5 years, simulating real-world commercial process conditions, and that was completed with good results. At present, design

and development efforts are under way for future implementation of WEPP at a 200 kt/y commercial phenol plant. Based on the pilot unit test results, the WEPP process selectivity for cumene feed is expected to be about 99.5 mol %, corresponding to a cumene usage of about 1283–1285 kg per ton of phenol.

Other important advantages of WEPP, as compared to even the best of conventional technologies, include, but are not limited to, a higher process safety level, significant engineering and operational simplification of the CHP cleavage stage (lowering capital expen-ditures and decreasing operational costs), and an exceptionally high quality of the desired process products.

Nevertheless, final results, with 100% accurate assessment of WEPP as compared to older technologies that have been in use for years, may only be obtained through its actual commercial implementation. Therefore, at this stage, the emphasis is placed on the fact that a competitive alternative option, to the conventionally designed phenol/acetone production process, is being made available with very optimistic and realistic expectations of future com-mercial implementation of a next-generation cumene-based phenol/acetone process.

REFERENCES

1. Nemtsov, M.S., Vospominaniya i razmyshleniya (Memories and Thoughts), St. Petersburg: RIO “SPb GIPT,” 2006, pp. 53–62. 2. Hock, H. and Lang, S., Berichte, 1944, vol. 77, nos. 3– 4, pp. 257–264. 3. Stephens, H.N., J. Am. Chem. Soc., 1926, vol. 48, pp. 1824–1826. 4. Stephens, H.N. and Roduta, F.L., J. Am. Chem. Soc., 1935, vol. pp. 2380–2381. 5. Kruzhalov, V.D. and Golovanenko, B.I., Sovmestnoe proizvodstvo fenola i acetone (Joint Phenol and Acetone Production),.Moscow: Goskhimizdat, 1963. 6. Zakoshansky, V.M., Phenol and Acetone: An Analysis of the Process Technologies, and of the Kinetics and the Mechanisms of Corresponding Major Reactions, St. Petersburg: Khimizdat, 2009. 7. (a) Emanuel, N.M., Denisov, E.T., and Maizus, Z.K., Tsepnye reaktsii okisleniya uglevodorodov v zhidkoi faze (Chain Oxidation Reactions of Hydrocarbons in Liquid Phase), Moscow: Nauka, 1965. (b) Knorre, D.G., et al., Usp. Khim., 1957, vol. 26, no. 4, pp. 416–458. (c) George, P. and Robertson, A., Trans. Faraday. Soc., 1946, vol. 42, nos. 3–4, pp. 217–229. (d) Emanuel, N.M.


ZAKOSHANSKY 22

and Gal, D., Okislenie etilbenzola. Modelnaya reaktsiya (Oxidation of Ethylbenzene. A Model Reaction), Moscow: Nauka, 1984. (e) Zakoshansky, V.M., et al., Abstract of Papers, Proc. of AIChE 1st Int. Aromatics Producers Conf., New Orleans, La., March 10–14, 2002, pp. 131–138. 8. Zakoshansky, V.M. and Budarev, A.V., Ros. Khim. Zh., 2008, vol. 52, no. 4, pp. 72–88. 9. Zakoshansky, V.M. and Budarev, A.V., Ros. Khim. Zh., 2008, vol. 52, no. 6, pp. 152–168. 10. Antonovsky, V.L. and Makalets, B.I., Dokl. Akad. Nauk SSSR, 1961, vol. 140, no. 5, pp. 1070–1072. 11. Zakoshansky, V.M., Griaznov, A.K. and Vasilieva, I.I., High Selective Method of Phenol and Acetone Production, US Patent no. 6 057 483, 2000. 12. Zakoshansky, V.M., Fedoseyev, F.G., Karasev, V.N., Eigin, S.V., Anfinogenova, T.S. and Moskovich, Yu.L., Method for Joint Phenol, Acetone, and α-Methylstyrene Production, 1987, RF Patent no. 1361937. 13. Moskovich, Yu.L., Eigin, S.V., Zakoshansky, V.M., et al., Method for Joint Phenol, Acetone, and α- Methylstyrene Production, RF Patent 1391030, 1987. 14. Zakoshansky, V.M., Moskovich, Yu.L., Gurfein, N.S., et al., Method for Joint Phenol, Acetone, and α- Methylstyrene Production, RF Patent no. 1563181, 1990. 15. Zakoshansky, V.M., Method for the Decomposition of Cumene Hydroperoxide by Acidic Catalyst to Phenol and Acetone, US Patent no. 5 254 751, 1993. 16. Griaznov, A.K., et al., Method for Automatic Control over a Cumene Hydroperoxide Cleavage Process, RF Patent no. 1699135, 1991. 17. Yuriev Yu.N. and Zakoshansky V.M., Abstracts of Papers, Proc. of the Conf. on the Phenol and Acetone production “Regularities of Acidic Cumene Hydroperoxide Decomposition Reaction,” Novo- kuibyshevsk, 1982, pp. 73–74. 18. Zakoshansky, V.M., Griaznov, A.K. and Vasilieva, I.I., Highly Selective Method for the Production of Phenol and Acetone from Cumene, RF Patent no. 2142932, 1999. 19. (a) Zakoshansky, V.M., Vasilieva, I.I., Griaznov, A.K., Yuriev, Yu.N., van Barnefeld, H., Gerlich, O., Kleine- Boymann, M., Kleinloh, W., and Michalic, C., Process for the Production of Phenol and Acetone from Cumene, US Patent no. 6 225 513, 2001. (b) Zakoshansky, V.M., Vasilieva, I.I., Griaznov, A.K., Youriev, Yu.N., van Barnefeld, H., Gerlich, O., Kleine-Boymann, M., Klein- loh, W., and Michalic, C., Improved Method for Producing Phenol and Acetone from Cumol, EP Patent no. 0944567, 1999. 20. Zakoshansky, V.M., Kataliz v promyshlennosti, 2004, no. 5, pp. 3–24. 21. Zakoshansky, V.M., Abstracts of Papers, Proc. of AIChE 3rd Int. Conf. on Aromatics and Derivatives

Formation of Key by-Products in Phenol Production Process, New Orleans, La., April 25–29, 2004, pp. 504– 512. 22. Zakoshansky, V.M., Zh. Obshch. Khim., 1989, vol. 59, no. 5, pp. 1122–1126. 23. Zakoshansky, V.M., et al., in Neftepererabotka i neftekhimiya: Collected works by CNIITEneftekhim, Moscow: CNIITEneftekhim, 1989, pp. 182–187. 24. Chulkov, V.P., Zakoshansky, V.M., et al., in: Neftepererabotka i neftekhimiya: Collected works by CNIITEneftekhim, Moscow: CNIITEneftekhim, 1989, pp. 187–192. 25. Vasilieva, I.I., Zakoshansky, V.M., and Koshelev, Yu.N., in Neftepererabotka i neftekhimiya: Collected works by CNIITEneftekhim, no. 12, 2009, pp. 34–38. 26. Vasilieva, I.I., Zakoshansky, V.M., and Koshelev, Yu.N., Abstracts of Papers, Proc. of the 13th Int. Sci. and Techn. Conf. “Reaktiv-2000,” Tula: TPGU, 2000, pp. 215–216. 27. Vasilieva, I.I., Zakoshansky, V.M., Koshelev, Yu.N., and Chulkov, V.P., Zh. Obshch. Khim., 2001, vol. 74, no. 1, pp. 107–110. 28. Zakoshansky, V.M., Kataliz v promyshlennosti, 2002, no. 1, pp. 29–41. 29. Zakoshansky, V.M., Neftekhimiya, 207, vol. 47, no. 4, pp. 301–313. 30. Zakoshansky, V.M., Artemov, A.V., and Antonovsky, V.L., Current State and Means of Intensification of Phenol and Acetone Production by Cumene Method: Topical Review, Ser. Neftepererabotka i slantsepererabotka, issue 6, Moscow: CNIITEneftekhim, 1988. 31. Zakoshansky, V.M., Kataliz v promyshlennosti, 2002, no. 5, pp. 9–22. 32. Zakoshansky, V.M., Dobrotvorsky, A.M., Pinson, V.V., and Chulkov, V.P., Zh. Obshch. Khim., 1986, vol. 56, no. 3, pp. 665–670. 33. VNIINEFTEKHIM Research Institute. “Development of a Cumene Hydroperoxide Cleavage Process in an Acetone-Excessive Medium,” Report prepared by VNIINEFTEKHIM Research Institute, Leningrad, 198. 34. Marshall Jr., B.K., De Caria, A.J., Hertzog, R.R., Sifniades, S., and Fisher, W.B., Decomposition of Cumene Oxidation Product, US Patent no. 7166752, 2007. 35. Zakoshansky, V.M., Yuriev, Yu.N., Idlis, G.S., and Aleksandrov, A.S., Zh. Fiz. Khim., 1984, vol. 58, no. 5, pp. 1265–1267. 36. Kislina, I.S., et al., Izv. Akad. Nauk SSSR, Ser. Khim., 1992, no. 1, pp. 72–77. 37. Maiorov, V.D. et al., Izv. Akad. Nauk SSSR, Ser. Khim., 1991, no. 5, pp. 1001–1006. 38. Zakoshansky, V.M., in: Protsessy neftepererabotki i neftekhimii: Collected works by VNIINeftekhim, St. Petersburg: GIORD, 2005, pp. 108–131.



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39. Zakoshansky, V.M., Griaznov, A.K., Vasilieva, I.I., et al., Utility-Saving and Highly Selective Method for Preparing Phenol and Acetone, RF Patent no. 2141938, 1999. 40. Sifniades, S., Tunick, A.A., and Koff, F.W., Decomposition of Cumene Oxidation Product, US Patent no. 4 358 618, 1982. 41. (a) Hood, H.E., Process for Producing Phenol from Cumene, US Patent 5 430 200, 1995. (b) Hood, H.E., Process for Producing Phenol from Cumene, US Patent no. 5371 305, 1994. 42. Blackborn, R.L., Allan, E.D., Le, L.B., and Patel, S., Cumene Hydroperoxide Cleavage Process, US Patent no. 5 463 136. 1995. 43. Yasaka, N. and Shirahata, T., Process for the Production of Phenol, US Patent no. 5 998 677, 1999. 44. Schmidt, R.J., Schulz, R.C., Bullen, P.J., et al., Decomposition of Cumene Hydroperoxide, US Patent no. 7 141 700, 2006. 45. Schmidt, R.J., Schulz, R.C., Bullen, P.J., et al., Decomposition of Cumene Hydroperoxide, US Patent no. 7 141 701, 2006. 46. Karnozhitsky, V., Organicheskie perekisi (Organic Peroxides), Moscow: Inostrannaya Literatura, 1961. 47. Zakoshansky, V.M. and Vassilieva, I.I., Method of Purifying Cumene Hydroperoxide Decomposition Products from Hydroxyacetone and from Other

Carbonyls, US Patent no. 6 066 767, 2000. 48. Zakoshansky, V.M., Vasilieva, I.I., and Koshelev, Yu.N., Abstracts of Papers, Proc. of AIChE 3rd Int. Aromatics Conf. on Aromatics and Derivatives, New Orleans, La., April 25–29, 2004, pp. 483–490. 49. Koshelev, Yu.N., Zakoshansky, V.M., Vasilieva, I.I., and Malov, Yu.I., Method for Removal of Impurities from Penol, RF Patent no. 2266275, 2005. 50. Zakoshansky, V.M., Malinovsky, A.S., Tseder- baum, V.G., et al., Method for Removing Organic Impurities from Phenol, RF Patent no. 2111203, 1998. 51. Zakoshansky, V.M., Vasilieva, I.I., and Griaznov, A.K., Method for Purification of Phenol, US Patent no. 5 502 259, 1996. 52. Schmidt, R.J., et al., Abstracts of Papers, Proc. of AIChE 7th Int. Conf. on Refinery Processing, New Orleans, La., April 25–29, 2004, pp. 49–503. 53. Blackborn, R.L., Allan, E.D., Le, L.B., and Patel, S., Cumene Hydroperoxide Cleavage Process, US Patent no. 5 463 136. 1995. 54. Gabutdinov, M.S., Kalashnikov, Ju.S., Shafigullin, A.S., et al., Method of Decomposing Cumene Hydroperoxide with Acid Catalyst to Phenol and Acetone, RF Patent no. 2114816, 1998. 55. Zakoshansky, V.M. and Vasilieva, I.I., Wasteless Ecоnоmic Methоd оf Prоductiоn оf Phenоl and Acetоne, US Patent no. 6 252 124, 2001.

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