Preface to First Edition

Petrochemicals in general are compounds and polymers derived direct- ly or indirectly from petroleum and used in the chemical market. Among the major petrochemical products are plastics, synthetic fibers, synthetic rubber, detergents, and nitrogen fertilizers. Many other important chem- ical industries such as paints, adhesives, aerosols, insecticides, and phar- maceuticals may involve one or more petrochemical products within their manufacturing steps.

The primary raw materials for the production of petrochemicals are natural gas and crude oil. However, other carbonaceous substances such as coal, oil shale, and tar sand can be processed (expensively) to produce these chemicals.

The petrochemical industry is mainly based on three types of interme- diates, which are derived from the primary raw materials. These are the C2-C 4 olefins, the C6-C8 aromatic hydrocarbons, and synthesis gas (an H2/CO 2 mixture).

In general, crude oils and natural gases are composed of a mixture of relatively unreactive hydrocarbons with variable amounts of nonhydro- carbon compounds. This mixture is essentially free from olefins. However, the C2 and heavier hydrocarbons from these two sources (nat- ural gas and crude oil) can be converted to light olefins suitable as start- ing materials for petrochemicals production.

The C6-C8 aromatic hydrocarbons--though present in crude oi l~are generally so low in concentration that it is not technically or economical- ly feasible to separate them. However, an aromatic-rich mixture can be obtained from catalytic reforming and cracking processes, which can be further extracted to obtain the required aromatics for petrochemical use. Liquefied petroleum gases (C3-C4) from natural gas and refinery gas streams can also be catalytically converted into a liquid hydrocarbon mixture rich in C6-C8 aromatics.

XIII

Synthesis gas, the third important intermediate for petrochemicals, is generated by steam reforming of either natural gas or crude oil fractions. Synthesis gas is the precursor of two big-volume chemicals, ammonia and methanol.

From these simple intermediates, many important chemicals and poly- mers are derived through different conversion reactions. The objec- tive of this book is not merely to present the reactions involved in such conversions, but also to relate them to the different process variables and to the type of catalysts used to get a desired product. When plausi- ble, discussions pertinent to mechanisms of important reactions are included. The book, however, is an attempt to offer a simplified treatise for diversified subjects dealing with chemistry, process technology, poly- mers, and catalysis.

As a starting point, the book reviews the general properties of the raw materials. This is followed by the different techniques used to convert these raw materials to the intermediates, which are further reacted to pro- duce the petrochemicals. The first chapter deals with the composition and the treatment techniques of natural gas. It also reviews the proper- ties, composition, and classification of various crude oils. Properties of some naturally occurring carbonaceous substances such as coal and tar sand are briefly noted at the end of the chapter. These materials are tar- geted as future energy and chemical sources when oil and natural gas are depleted. Chapter 2 summarizes the important properties of hydrocarbon intermediates and petroleum fractions obtained from natural gas and crude oils.

Crude oil processing is mainly aimed towards the production of fuels, so only a small fraction of the products is used for the synthesis of olefins and aromatics. In Chapter 3, the different crude oil processes are reviewed with special emphasis on those conversion techniques employed for the dual purpose of obtaining fuels as well as olefinic and aromatic base stocks. Included also in this chapter, are the steam crack- ing processes geared specially for producing olefins and diolefins.

In addition to being major sources of hydrocarbon-based petrochemi- cals, crude oils and natural gases are precursors of a special group of compounds or mixtures that are classified as nonhydrocarbon intermedi- ates. Among these are the synthesis gas mixture, hydrogen, sulfur, and carbon black. These materials are of great economic importance and are discussed in Chapter 4.

Chapter 5 discusses chemicals derived directly or indirectly from methane. Because synthesis gas is the main intermediate from methane,

xiv

it is again further discussed in this chapter in conjunction with the major chemicals based on it.

Higher paraffinic hydrocarbons than methane are not generally used for producing chemicals by direct reaction with chemical reagents due to their lower reactivities relative to olefins and aromatics. Nevertheless, a few derivatives can be obtained from these hydrocarbons through oxida- tion, nitration, and chlorination reactions. These are noted in Chapter 6.

The heart of the petrochemical industry lies with the C2-C4 olefins, butadiene, and C6-C8 aromatics. Chemicals and monomers derived from these intermediates are successively discussed in Chapters 7-10.

The use of light olefins, diolefins, and aromatic-based monomers for producing commercial polymers is dealt with in the last two chapters. Chapter 11 reviews the chemistry involved in the synthesis of polymers, their classification, and their general properties. This book does not dis- cuss the kinetics of polymer reactions. More specialized polymer chem- istry texts may be consulted for this purpose.

Chapter 12 discusses the use of the various monomers obtained from a petroleum origin for producing commercial polymers. Not only does it cover the chemical reactions involved in the synthesis of these polymers, but it also presents their chemical, physical and mechanical properties. These properties are well related to the applicability of a polymer as a plastic, an elastomer, or as a fiber.

As an additional aid to readers seeking further information of a specif- ic subject, references are included at the end of each chapter. Throughout the text, different units are used interchangeably as they are in the indus- try. However, in most cases temperatures are in degrees celsius, pressures in atmospheres, and energy in kilo joules.

The book chapters have been arranged in a way more or less similar to From Hydrocarbons to Petrochemicals, a book I co-authored with the late Professor Hatch and published with Gulf Publishing Company in 1981. Although the book was more addressed to technical personnel and to researchers in the petroleum field, it has been used by many colleges and universities as a reference or as a text for senior and special topics courses. This book is also meant to serve the dual purpose of being a ref- erence as well as a text for chemistry and chemical engineering majors.

In recent years, many learning institutions felt the benefits of one or more technically-related courses such as petrochemicals in their chem- istry and chemical engineering curricula. More than forty years ago, Lewis Hatch pioneered such an effort by offering a course in "Chemicals from Petroleum" at the University of Texas. Shortly thereafter, the ter

XV

"petrochemicals" was coined to describe chemicals obtained from crude oil or natural gas.

I hope that publishing this book will partially fulfill the objective of continuing the effort of the late Professor Hatch in presenting the state of the art in a simple scientific approach.

At this point, I wish to express my appreciation to the staff of Gulf Publishing Co. for their useful comments.

I wish also to acknowledge the cooperation and assistance I received from my colleagues, the administration of KFUPM, with special mention of Dr. A. A1-Arfaj, chairman of the chemistry department; Dr. M. Z. E1- Faer, dean of sciences; and Dr. A. A1-Zakary, vice-rector for graduate studies and research, for their encouragement in completing this work.

Sami Matar, Ph.D.

xvi