Sulfonic Containing Polymer Bead Synthesized through ...downloads.hindawi.com/journals/apt/2019/4854620.pdfwt%Tween(STb)system.esulfurelementratio can also be calculated from ion exchange

Research ArticleSulfonic Containing Polymer Bead Synthesized throughInverse Suspension Polymerization and Its Characteristics forEsterification Catalyst

Cengliang Shan Ye Wang Jun Nie and Yong He

State Key Lab of Chemical Resource Engineering and Key Laboratory of Carbon Fiber and Functional PolymersMinistry of Education Beijing University of Chemical Technology Beijing 100029 China

Correspondence should be addressed to Yong He heyongmailbucteducn

Received 12 December 2018 Revised 15 March 2019 Accepted 11 April 2019 Published 2 May 2019

Academic Editor Leonard D Tijing

Copyright copy 2019 Cengliang Shan et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The sulfonic containing polymer bead was synthesized using sodium p-styrenesulfonate (SSS) and NN1015840-methylenebisacrylamide(MBA) through inverse suspension polymerization and evaluated as catalyst for esterification of of n-octanol and acrylic acid Theinfluence of some principal factors such as combination dispersant crosslink agent content posttreatment methods and porogentypes was investigated in detail The results showed that the morphology and characteristics of polymer beads were controllableThe polymer beads with 20wt crosslink agent showed the best catalysis ability achieving almost 96 esterification conversion atthe first time and 80 after 5 cycles

1 Introduction

Ester as one of most important industrial chemicals is com-mercially synthesized by esterification or transesterificationusually employing strong mineral acid as catalyst whichcould deteriorate the esterification product quality in somedegree Due to the increasing demand of environmentalprotection the problem of the disposal of catalyst wastehas gradually attracted peoplersquos attention and stimulated thesearching for recyclable solid catalyst to replace conventionaltoxic and corrosive acid [1 2] Therefore there were manyattempts with different mechanism and structure reportedsuch as heteropoly acids [3] zeolites [4] layered material[5] ion exchange resin [6] or enzyme [7 8] Among themion exchange resin undoubtedly received more and moreattention because it is one of the most widely used materialsin many applications for their excellent performance andpossesses obvious engineering benefits of easy separationnoncorrosivity and reusability [9 10]

Sert [11] studied three different ion exchange resinsAmberlyst 15 Amberlyst 131 and Dowex 50Wx-400 as cata-lyst for the esterification of acrylic acid and n-butanol Theyinvestigated the effects of different variables temperature

molar ratio of alcohol to acid stirrer speed and catalystloading on the reaction rate and concluded that Amberlyst 131is the most efficient catalyst giving the maximum conversionof acrylic acid Styrene-divinylbenzene (St-DVB) copolymerbead was firstly synthesized in the 1960s by suspensionpolymerization and could be donated sulfonic group (SO

3H)

through sulfonation to form ion exchange resin [12] Itwas proved that the catalysis efficiency of sulfonated poly-divinylbenzene (polyDVB-SO

3H) can be analogized to com-

mercial ion-exchange resins (Amberlyst 35 and Amberlyst36) by Aguiar [13] and it was revealed that higher sulfonationhigher ion capacity and lower carboxylation were desirable[14] All of the abovementioned systems have to involvea complicated sulfonation process to modify the polymerwhich could lead to oxidation degradation difficulty incontrolling the morphology or active group ratio due tolong time contact with sulfuric and nitric acidTherefore thepolymerization of sulfonic containing monomer would be asolution to overcome these problems and to prepare higherquality catalyst beads with good catalyzed ability stabilityand probability to adjust the morphology

Inverse suspension polymerization is one of the bestmethods to form polymer particle from water soluble

HindawiAdvances in Polymer TechnologyVolume 2019 Article ID 4854620 8 pageshttpsdoiorg10115520194854620

2 Advances in Polymer Technology

monomer with high stability narrow particle size distribu-tion fast process rate and high conversion [15 16] It isreasonable to be adopted in preparation of new polymerbeads catalyst with sulfonic containing monomer

In this work we aimed to design and prepare a kindof pore size and morphology controllable reusable polymerbead catalyst for esterification using sulfonic containingmonomer through inverse suspension polymerization Theinfluence of several key factors for the polymer beads catalystability particle size and morphology such as the dispersantcrosslink agent porogen and preparing condition was inves-tigated The catalysis ability regarding the esterification ofacrylic acid and n-octanol was evaluated

2 Experiment

21Material Sodium p-styrene sulfonate (SSS) was obtainedfrom Shandong Star Alliance Biotechnology Co (Shan-dong China) NN1015840-methylenebisacrylamide (MBA) andp-hydroxyanisole were supplied by Tianjin Guangfu FineChemical Institute (Tianjin China) Persulfate liquid paraf-fin acrylic acid 119899-octanol span60 and tween60 werepurchased from Tianjin Fuchen Chemical Reagent Factory(Tianjin China) Propanediol n-butanol 14ndashbutanedioland polyethylene glycol (PEG200 PEG400 PEG600) weresupplied by Beijing Chemical Works (Beijing China) Allregents were of analytical grade and used without furtherpurification

22 Polymer Beads Characterization The Fourier transforminfrared spectra (FT-IR) were recorded on Nicolet 5700(Nicolet Instrument Thermo Company USA) Samples wereprepared with KBr powder and pressed into flake

The sulfonic group content was represented from the totalamount of sulfur as measured by elemental analysis (CHNSMode Elementar Analysensysteme GmbH Company Ger-man) through burnt polymer at high temperature

The titration was used to measure ion exchange capacityThe pretreated polymer beads with acid were dried by freeze-drying for a whole day and 40 mg beads were takensuspended in 10 mL deionized water and titrated with 01molL standard NaOH aqueous solution in the presence ofa phenolphthalein indicator [17ndash19]

Laser scattering particle size distribution analyzer(MalvernMastersizer 2000UK)was used tomeasure particlesize and size distribution of polymer beads with ethanol asdispersant Themedian particle size and microsphere surfacearea per unit volume (SPArea) were adopted to characterizethe particle size A larger median particle size and a smallerSPArea indicated the increase of particle size [20] Here inorder to better characterize the size distribution of copolymermicrospheres we referred to the knowledge of mathematicalstatistics and introduce the coefficient of variation (CV) as aparameter

CV = 120590120583 (1)

where 120590 is the sample standard deviation and 120583 is thearithmetic mean of particle size Coefficient of variation is

a statistic that can measure the variation extent of eachobserved variation and quantifies the width of the distri-bution function relative to its mean A larger coefficientof variation indicates that the distribution of the observedvariation is less concentrated [21]

23 Synthesis of Ion Polymer Beads The polymer beadswere prepared by the inverse suspension polymerizationmethod The monomer and crosslink agent mixture solutionwas prepared by fully dissolving 6 g sodium p-styrenesulfonate (SSS monomer) predetermined amount of NN1015840-methylenebisacrylamide (MBA crosslink agent) 024 g per-sulfate (initiator) 20 mL deionized water and differentporogen with 30 min ultrasound treatment Then 048 gdifferent dispersant and 75mL liquid paraffin (oil phase) wereadded to 250ml four-necked flask with mechanical stirrerand immersed in a thermostatically controlled heating unitwith temperature of 50∘C for 30 min until the oil phasewas fully melted Then the monomer and crosslink agentmixture solution was poured into 250 ml four-necked flaskequipped with mechanical stirring and reflux condenserunder vigor stirring to produce the inverse suspensionsystem At last the temperature was raised up to 90∘C andmaintained for 4 hours with agitation to perform polymer-ization After polymerization the polymer beads were filteredout and rinsed off three times with ethanol and deionizedwater separately to remove the unreacted materials anddried

The obtained beads were characterized by FT-IR Thecharacteristic peaks around 1184 cmminus1 (sulfonate group) 1041cmminus1 (benzene ring) 833 cmminus1 (14-disubstituted benzene)and 1655 cmminus1 (amide group) demonstrated the target prod-uct was successfully synthesized

24 Acidification and Esterification Evaluation ProcedureDifferent from the traditional complex process to change thepolymer beads into ion exchange resin through sulfonation[22] the sulfonic groups could form after just immersing thesynthesized polymer beads containing sulfonate groups intoconcentrated hydrochloric acid for 4 hours at room temper-ature in our study After the acidification the beads werepoured slowly into deionized water and washed by deionizedwater until the effluent was free of acid This is the pretreat-ment process of the synthesized resin beads Then the beadswere completely ready to begin the catalyzing evaluationprocedureThe esterification reaction was performed in four-necked round-bottomflask equippedwithmechanical stirrercondenser and water splitterThe flask was then immersed ina thermostatically controlled heating unit Acrylic acid and119899-octanol were added to the reactor with the weight ratio of171 accompanied with azeotropic solvent toluene inhibitor4-methoxyphenol (01 wt) and the polymer beads (5 wtin dry weight) after pretreatment and then the esterificationwas performed at the temperature of 110∘C for 5h After theexperiment the catalysts were filtered out from solution andwashed by acetone and deionizedwater three times separatelyto prepare for the next esterification

The esterification was traced by gas chromatographyDuring the reaction a series of 05 mL reaction solutions

Advances in Polymer Technology 3

Table 1 Effect of dispersant on sulfur content and ion exchange capacity of polymer beads

Combinationdispersant

Tween60Span60(ww)

S(wt) by elementalanalysis

Ion exchange capacity(mmolg)

Slowast (wt)by titration

S60 010 923 252 806ST66a 28 1081 225 72ST66b 46 958 270 864ST66c 55 935 255 816ST66d 64 740 198 634ST66e 82 688 175 560T60 100 601 185 592MBA15 wt of SSS no porogen

were taken out at specific time intervals and diluted withmethylene chloride to the concentration of 8 wt The gaschromatography (GC2014c Shimadzu Company Japan) wasequipped with a thermal conductivity detector and column(GsBP-5 model) with hydrogen as a carrier gas at 300∘CDuring the analysis all peaks appeared within ten minutesThe esterification conversion is calculated as follows

119862119900119899V119890119903119904119894119900119899 =(11987811198721)

(11987811198721+ 11987821198722)lowast 100 (2)

where 1198781is the peak area of octyl acrylate 119872

1is the

molecular weight of octyl acrylate 1198782is the peak area of 119899-

octanol and1198722is the molecular weight of 119899-octanol

3 Results and Discussion

31 Influence of Dispersant Dispersant plays a key role instabilization of polymerization system and subsequently in-fluences the content of monomers in obtained polymer beadand its morphology For this kind of inverse suspensionpolymerization the nonionic dispersant such as Tween andSpan series was suitable selection based on our previouswork [23] After some pretest the Tween60 and Span60 werechosen and the effect of their ratio on the product propertieswas investigated at first

It could be seen from Table 1 that the sulfur elementratio (S) which represents the SO

3H group amount of pure

Tween60 as dispersant system (T60) was much lower thanthat of pure Span60 system (S60) and combination systemwith 80 wt Span60 and 20 wt Tween60 (ST66a) showedthe largest value The higher the sulfur content the higherthe sulfonic group content and the better the catalysis abilityThis kind of difference reflected the ratio of sodium styrenesulfonate and the crosslink agent in produced polymer beadThe ratio is decided by dispersant type because differentdispersant combination can lead to different SSS content inaqueous solution drop to form polymer bead and furtherresult in different S content in bead Almost the same trendwas observed in ion exchange capacity except that themaximum value was obtained in the 60 wt Span60 and40 wt Tween60 (ST66b) system The sulfur element ratiocan also be calculated from ion exchange capacity whichwas listed in Table 1 (Slowast) The values of Slowast are a little lowerthan S which is due to the limitation of penetration of

200

400

600

800

1000

1200

1400

00110

00115

00120

00125

00130

00135

00140

Y1 Y2 Y3

Y2

SPA

rea (

cm2 g

)

Y3

CV

ST660a ST660b ST660c ST660d ST660e T60S60

Combination dispersant

100

200

300

400

500

600

Y1M

edia

n siz

e (um

)

Figure 1 Effect of dispersant on polymer beads size and dispersionMBA15 wt of SSS no porogen

alkane aqueous solution into the interior of the polymerbead However as the catalyst ion exchange capacity shouldbe more important than sulfur content because it directlydecided the amount of reactive site and determined thereaction rate

At the same time S60 system showed minimum mediansize (Y1) and maximum SP Area (Y2) and CV (Y3) whichmeant the smallest particle size and largest size dispersion(Figure 1) With the increasing of the Tween60 ratio theparticle size went up then down but the size dispersion downthen up which could be because higher lipophilic of Span60could make the monomer aqueous solution drops in a morestable way and combination dispersant always benefits thesuspension polymerization [24]

From the view of catalysis effect larger surface area perunit volume was always preferable but too small particlesize could make postprocessing and recycling very difficultSo ST66b was selected as optimal dispersant combinationto conduct the next step work due to its moderate particlesize dispersion the first highest ion exchange ability and thesecond highest function group ratio

32 Influence of Posttreatment Commonly the posttreat-ment is just a process to get rid of the unpolymerized


abc

1 2 3 40Esterification time (h)

0

10

20

30

40

50

60

)

(noisrevno

C

Figure 2 Esterification conversion curve with the gel-type beadsin swollen form (a) the dried beads with (b) and without (c)acidification process MBA15 wt of SSS no porogen

monomer dispersant or other additives However this pro-cedure in our investigated system was found to play a veryimportant role for the performance of the polymer beadsThree different methods were compared the first one was gel-type beads obtained through soaking the polymer bead afterposttreatment in ionized water for 4 h the second one wasdried beads after posttreatment and the third one was driedbeads before posttreatment

In Figure 2 curve (a) represented the first method andcurve (b) the second method while curve (c) represented thethird one It could be seen that the polymer beads producedfrom the first method exhibited the best catalysis effectaround 55 The curve of the second method showed onlyslightly over 15 conversion and the unacidified one gavejust about 6 result It was very easy to understand the trendof curve c because of lack of proton generation ability Thedifference between the first and second method could beattributed to two factors morphology and acidity

The first method could make the polymer bead formbigger and looser structure because both the monomerand crosslink agent are hydrophilic and can absorb andmaintain lots of water It couldmake acid alcohol and solventpenetrate inside of the beads and contact with catalysis sitemore easily The adsorbed water can be moved out of thesystem by water splitter and will not affect the esterificationHowever the dry beads from the second method weredifficultly swollen by the acid alcohol or ester and wouldkeep tight state in the esterification process which limited itscatalysis ability This was proved by the photographs of twodifferent kinds of polymer beads in Figure 3 The diameterof the first method product is almost 8 times larger than thesecond one

Furthermore as M Hartrsquos work has shown when resinsare used as dry state changing the structural features such asthe presence of sulfone bridges the degree of disubstitution

Table 2 Effect of crosslink agent content on sulfur content and ionexchange capacity of polymer beads

Crosslinkagent

(wt of SSS)

S (wt)Ion exchange

capacity(mmolg)

measured normalized measured calculatedC10 909 1038 1142 325 031C15 1304 954 1097 270 028C20 1667 892 1070 240 027C25 2000 828 1035 225 027C30 2308 703 914 187 0278 wt ST66b no porogen

could increase acid strength [17] But while in the state ofswelling in water the sulfonic content could form internalsolution inside the polymer beads which would increase theacid strengths because of the forming of hydronium ion Sothe second method would be adopted in the further work

33 Influence of Crosslink Agent The crosslink agent mightimprove crosslink density and lead to high mechanicalstrength good heat resistance and high duration [25] but atthe same time it could bring some other shortcomings Thechoice of crosslink agent amount would have a great impacton the final properties of polymer beads

NN1015840-methylenebisacrylamide one difunctional mono-mer was taken as crosslink agent and would influence thedensity structure and morphology of polymer beads Withthe ratio of MBA increased it was easily understood thatthe sulfur content (S) and ion exchange capacity woulddecrease due to the concentration effect (Table 2) Butnormalized S value obtained with measured S dividedby the corresponding monomer weight percentage revealedthat the increase of crosslink agent indeed declined themonomer conversion and subsequently decreased the ionexchange capacity more remarkably While the crosslinkagent ratio increased from C10 to C30 the S went downabout 32 but the normalized S decreased about 20which could not be simply attributed to the concentrationeffect alone It was believed that excess crosslink agent wouldindeed decrease the conversion of sulfonic group containingmonomer because too much crosslink agent could lead itshigher ratio in the polymer beads due to its better polymer-ization activity and the earlier reaching of vitrification point[16]

In Table 2 two different expressions of ion exchangecapacity parameters were included One is measuring ionexchange capacity obtained from titration method whichis the real ion exchange capacity and could represent thecatalysis active sites number Another is calculating ionexchange capacity value obtained with the value of measuredion exchange capacity divided by the value of measured Swhich was used to understand the effect of crosslink agentcontent on morphology uniformity The results showed thatthemeasure values decreased reasonably upon the increase ofcrosslink agent content due to concentration effect Howeverthe calculated values exhibited very little variation among


260m

(a)

2260m

(b)

Figure 3 Photographs for polymer beads with different posttreatment (a) with vacuumdrying after acidification (b) without vacuumdryingafter acidification process (scale bar is 200 120583m) 8 wtST66b [MBA] =15 wt of SSS no porogen

Table 3 Highest esterification conversion of polymer beads withdifferent crosslink agent content

Highest esterification conversionC10 647C15 712C20 959C25 313C30 1558 wt ST66b no porogen

these formulas except the C10 sample which seems just dueto the concentration effect The trend demonstrated that themorphology of polymer beads with different crosslink agentcontent remained almost the same because the ion exchangecapacity measure result was decided by sulfonic number andthe swollen ability of polymer beads in titration solution atthe same time

Light scattering result showed that the particle size grad-ually decreased with the crosslink agent content increased(Figure 4) and there was platform in C20 and C25 anda sharp decrease to C30 sample The median size of C10sample was about 450 120583m and that of C30 was about 270120583m But at the same time the coefficient of variation (CV)curve exhibited a trend of going down and then up whichmeans that uniformity of polymer beads became better thenworse and gave the best value at C20 sample It was becausetoo high polymerization rate resulting from excess crosslinkagent would lead to the deterioration of inverse emulsionstability and form less uniform smaller particle

The catalysis ability of this series polymer beads wasvalued in the synthesis of n-octyl acrylateThe results (Table 3and Figure 5) showed that they all could catalyze the esteri-fication reaction but the efficiency lied in the broad rangeThe C10 C15 and C20 exhibited much better catalysis abilitywhile C25 and C30 were not satisfied In particular the C20sample could reach up to 96 highest conversion in the firstcycle and showed very good reusabilityThe conversion in thefifth cycle can still achieve more than 80 which is muchbetter than the first cycle exhibition of commercial catalystsresin Amberlyst 15 (78) [26] in acetic acid and n-butanolsystem In addition the conversion of C20 was also much

450

500

550

600

650

700

750

800

00112

00113

00114

00115

00116

00117

Y1Y2Y3

Y2S

PA

rea (

cm2

g)

Y3C

V

250

300

350

400

450

Y1M

edia

n siz

e (um

)

J15 J20 J25 J30J10Crosslink agent ratio

Figure 4 Median size CV and SP Area of polymer beads withdifferent crosslink agent ratio 8 wtST66b no porogen

better than some other ion exchange resin for different aid-alcohol systems such as Dowex 50WX (350 acrylic acidwith ethanol) [8] Amberlyst 131 (434 acrylic acid with n-butanol) [11] Indion 130 (682 acetic acid with methanol)[27] Dowex 50 WX2 (701 acetic acid with isobutanol)[28] PDVB-01-SO

3H (882 hexanoic acid with ethanol)

[29] The decrease of conversion upon cycles increasing wascertainly observed which is due to the detachment of sulfonicgroup in esterification some product gelling to block thepores of the polymer bead and some broken beads

The excellent property of C20 could be attributed not onlyto its second highest sulfur content median particle size andbest size distribution but also to the good crosslink densityresulting from the proper crosslink agent concentration Andfurther we believed that it should have relationships withthe morphology and inner structure [30] The morphologyand topography of the beads were observed by SEM Thespherical morphology of the resin beads could be seen inFigure 6 while there were some small holes on the surface ofthe polymer beads It could be explained that no or very littlecrosslinked polymers could be washed away by deionizedwater to form the pores in the process of posttreatment Itwould be beneficial to improve the effective surface area of


C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC

1 2 3 4 50Esterification time (h)

Figure 5 Esterification conversion curves with C20 polymer beadsat different cycles 8 wt ST66b no porogen

Figure 6 SEMmicrograph of C20 polymer beads 8 wt ST66b noporogen

polymer beads so that acid alcohol and ester in esterificationreaction could contactwith catalyst adequately to achieve suf-ficient catalysis which was not observed for other formulas

34 Effect of Porogen Furthermore other six different alco-hol compounds propanediol n-butanol 14-butanediol andthree different molecular weight polyethylene glycols werechosen as porogen to investigate their effect on the propertieson catalyzing ability because the pore size and porositywere usually controlled by three experimental parametersporogen types amount of porogen and crosslink density [31]

The first three porogens in Table 4 were short carbonchain alcohols with one hydroxyl group for P2 and twohydroxyl groups for P1 and P3 The last three were polyethy-lene glycol with different length of carbon chain for twohydroxyl groups It was shown that P2 has the maximumsulfur content and ion-exchange capacity which were biggerwhile the rest of porogen appeared to be smaller thanthat without porogen C20 It meant that only n-butanolcould improve the polymerization reaction due to its lowestsolubility in water which makes it have almost no influenceon the stability of liquid drop And at the same time P2 also

Table 4 Effect of different porogen on polymer beads

Porogen S (wt) byelemental analysis

Ion exchangecapacity(mmolg)

P1 propanediol 748 153P2 n-butanol 1015 282P3 14-butanediol 828 185P4 PEG200 843 255P5 PEG400 870 195P6 PEG600 744 1658 wt ST66b MBA20 wt of SSS

P-6P-5P-4P-3P-2Porogen

P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)

Figure 7 Maximum esterification conversion of polymer beadswith different porogens 8 wt ST66b MBA 20 wt of SSS

exhibited the highest catalysis ability (Figure 7) which wasnot only caused by the difference in ion-exchange capacitybut also believed to have something with their size andmorphology

It was found that the median size and SP Area of P2(Figure 8) showed just medium value which implied thatparticle size was not the main reason for their catalysisperformance Further the morphology results could give asatisfied insight of this phenomenon The polymer beadscould be found with lots of pores on surface (Figure 9(a)) andholes inside the beads (Figure 9(b)) which would certainlyincrease the effective catalysis surface But other systemstaking P5 as an example (other four porogens showed similarresults) showed different structure which was only onecenter hole and smooth external and internal surface inFigure 9(c) This could also be attributed to the differentsolubility of porogen in water better solubility could lead toexistence as solution and not take effect as porogen

But it should be addressed that the catalysis ability ofthese samples using porogen system was still less than thatof C20 which might be due to their mechanical strength Itcan be clearly seen from the SEM pictures that some holeshave collapsed So how to select the better porogen andinvestigating their mechanism would be the next work


400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)

P-2 P-3 P-4 P-5 P-6P-1Porogen

00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V

Figure 8 Median size CV and SP Area of polymer beads with different porogens 8 wt ST66b MBA 20 wt of SSS

(a)

(a)

(b)

(b)

(c)

(c)

Figure 9 SEM micrographs of P-2 with magnification in 200 (a) 5000 (b) and P-5 with magnification in 250 (c) 8 wt ST66b MBA 20wt of SSS

4 Conclusions

In this work we synthesized the ion exchange polymer beadscatalyst containing sulfonic group for esterification reactionby inverse suspension polymerization The combination ofTween60 and Span60 with the proportion of 46 was selectedas optimal dispersant system for its moderate particle sizeand dispersion best function group ratio and ion exchangeability Keeping polymer beads in swollen state was provedto be better posttreatment to form catalyst because of thepossibility of formation inner acid solution in esterificationprocess C20 with 20 wt crosslink agent showed bestcatalysis ability and repeating properties due to high sulfurcontent median particle size best size distribution andforming of pores It could reach up to 96highest conversionand be reused up to 5 times and still achieve 80 conver-sion which was even better than some commercial catalystButanol was the best porogen among the investigated systemsdue to its lowest solubility in water but its catalysis ability wasless than C20 because of lower mechanical characters

Data Availability

The data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

The authors declare no competing financial interest

Acknowledgments

The authors thank the National Key Research and Devel-opment Program of China (2017YFB0307800) and NationalNatural Science Foundation of China (51373015 and 51573011)for their financial support

References

[1] X Wang R Liu M M Waje et al ldquoSulfonated orderedmesoporous carbon as a stable and highly active protonic acidcatalystrdquo Chemistry of Materials vol 19 no 10 pp 2395ndash23972007

[2] K Tanabe and W F Holderich ldquoIndustrial application of solidacidndashbase catalystsrdquo Applied Catalysis A General vol 181 no 2pp 399ndash434 1999

[3] A Corma and H Garcıa ldquoLewis acids from conventionalhomogeneous to green homogeneous and heterogeneous catal-ysisrdquo Chemical Reviews vol 103 no 11 pp 4307ndash4366 2003

[4] T Okuhara ldquoWater-tolerant solid acid catalystsrdquo ChemicalReviews vol 102 no 10 pp 3641ndash3666 2002


[5] C Tagusagawa A Takagaki S Hayashi and K Domen ldquoEf-ficient utilization of nanospace of layered transition metaloxide HNbMoO

6as a strong water-tolerant solid acid catalystrdquo

Journal of the American Chemical Society vol 130 no 23 pp7230-7231 2008

[6] M A Harmer and Q Sun ldquoSolid acid catalysis using ion-exchange resinsrdquo Applied Catalysis A General vol 45 p 2212011

[7] S Chang and J Shaw ldquoBiocatalysis for the production ofcarbohydrate estersrdquoNew Biotechnology vol 109 p 26 2009

[8] G Jyoti A Keshav J Anandkumar and S Bhoi ldquoHomogeneousand heterogeneous catalyzed esterification of acrylic acid withethanol reaction kinetics and modeling kinetics and modelingof esterification of acrylic acid with ethanolrdquo InternationalJournal of Chemical Kinetics vol 50 no 5 pp 370ndash380 2018

[9] A Chakrabarty and M M Sharma ldquoCationic ion exchangeresins as catalystrdquo Reactive Polymers vol 20 no 1-2 pp 1ndash451993

[10] M M Sharma ldquoSome novel aspects of cationic ion-exchangeresins as catalystsrdquo Reactive and Functional Polymers vol 26no 1-3 pp 3ndash23 1995

[11] E Sert AD Buluklu S Karakus and F S Atalay ldquoKinetic studyof catalytic esterification of acrylic acid with butanol catalyzedby different ion exchange resinsrdquo Chemical Engineering andProcessing Process Intensification vol 73 pp 23ndash28 2013

[12] K A Kun R Kunin and J Polym ldquoMacroreticular resins IIIFormation of macroreticular styrenendashdivinylbenzene copoly-mersrdquo Journal of Polymer Science Part A-1 Polymer Chemistryvol 6 no 10 pp 2689ndash2701 1968

[13] V M de-Aguiar A L F de-Souza F S Galdino M M C da-Silva V G Teixeira and E R Lachter ldquoSulfonated poly(div-inylbenzene) and poly(styrene-divinylbenzene) as catalysts foresterification of fatty acidsrdquo Renewable Energy vol 114 pp 725ndash732 2017

[14] M A Malik S W Ali and I Ahmed ldquoSulfonated styreneminusdivinybenzene resins optimizing synthesis and estimatingcharacteristicsof the base copolymers and the resinsrdquo Industrialamp Engineering Chemistry Research vol 49 no 6 pp 2608ndash26122010

[15] S Kiatkamjornwong andP Phunchareon ldquoInfluence of reactionparameters on water absorption of neutralized poly(acrylicacid-co-acrylamide) synthesized by inverse suspension poly-merizationrdquo Journal of Applied Polymer Science vol 72 no 10pp 1349ndash1366 1999

[16] CMayoux J Dandurand A Ricad and C Lacabanne ldquoInversesuspension polymerization of sodium acrylate synthesis andcharacterizationrdquo Journal of Applied Polymer Science vol 77 no12 pp 2621ndash2630 2000

[17] M Hart G Fuller D R Brown J A Dale and S Plant ldquoSul-fonated poly(styrene-co-divinylbenzene) ion-exchange resinsacidities and catalytic activities in aqueous reactionsrdquo Journalof Molecular Catalysis A Chemical vol 182ndash183 pp 439ndash4452002

[18] T R Theodoro J R Dias J L Penariol J OV Mouraand L G Aguiar ldquoSulfonated poly (styrene-co-ethylene glycoldimethacrylate) with attractive ion exchange capacityrdquo Poly-mers for Advanced Technologies vol 29 no 11 pp 2759ndash27652018

[19] W B Ying J U Jang M W Lee T S Hwang K J Leeand B Lee ldquoNovel flexible styrenic elastomer cation-exchangematerial based on phenyl functionalized polystyrene-butadiene

copolymerrdquo Journal of Industrial and Engineering Chemistryvol 1289 p 47 2017

[20] P Liang Z Jiang Z Meng J Nie and Y He ldquoInvestigation ofstabilizer-free dispersion polymerization process of styrene andmaleic anhydride copolymer microspheresrdquo Journal of PolymerScience Part A Polymer Chemistry vol 48 no 24 pp 5652ndash5658 2010

[21] Z Sun ldquoStudy on usage of coefficient of variation for statisticsofmagnetic parameters of samplesrdquoGeologyamp Exploration vol65 p 45 2009

[22] C Martin and J Cuellar ldquoSynthesis of a novel magnetic resinand the study of equilibrium in cation exchange with aminoacidsrdquo Industrial amp Engineering Chemistry Research vol 43 no2 pp 475ndash485 2004

[23] F P Wu M Q Shi Y L Zhang Y X Zhang and Y HeldquoNano water-soluble microgel oil displacement material andpreparation methodrdquo ZL2005100122550 2005

[24] E Vivaldo-Lima P E Wood and A E Hamielec ldquoAn updatedreviewon suspension polymerizationrdquo Industrial amp EngineeringChemistry Research vol 36 no 4 pp 939ndash965 1997

[25] C A Toro R Rodrigo and J Cuellar ldquoSulfonation of macro-porous poly(styrene-co-divinylbenzene) beads effect of theproportion of isomers on their cation exchange capacityrdquoReactive and Functional Polymers vol 68 no 9 pp 1325ndash13362008

[26] J Gangadwala S Mankar and S Mahajani ldquoEsterification ofacetic acid with butanol in the presence of ion-exchange resinsas catalystsrdquo Industrial amp Engineering Chemistry Research vol42 no 10 pp 2146ndash2155 2003

[27] P E JagadeeshBabu K Sandesh andM B Saidutta ldquoKinetics ofesterification of acetic acid withmethanol in the presence of ionexchange resin catalystsrdquo Industrial amp Engineering ChemistryResearch vol 50 no 12 pp 7155ndash7160 2011

[28] A Izci and F Bodur ldquoLiquid-phase esterification of acetic acidwith isobutanol catalyzed by ion-exchange resinsrdquo Reactive andFunctional Polymers vol 67 no 12 pp 1458ndash1464 2007

[29] F J Liu X Meng Y L Zhang L M Ren F Nawaz and FS Xiao ldquoEfficient and stable solid acid catalysts synthesizedfrom sulfonation of swelling mesoporous polydivinylbenzenesrdquoJournal of Catalysis vol 271 no 1 pp 52ndash58 2010

[30] M A Tejero E Ramırez C Fite J Tejero and F CunillldquoEsterification of levulinic acid with butanol over ion exchangeresinsrdquo Applied Catalysis A General vol 517 pp 56ndash66 2016

[31] W L Sederel and G J De Jong ldquoStyrenendashdivinylbenzenecopolymers Construction of porosity in styrene divinylbenzenematricesrdquo Journal of Applied Polymer Science vol 17 no 9 pp2835ndash2846 1973

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monomer with high stability narrow particle size distribu-tion fast process rate and high conversion [15 16] It isreasonable to be adopted in preparation of new polymerbeads catalyst with sulfonic containing monomer

In this work we aimed to design and prepare a kindof pore size and morphology controllable reusable polymerbead catalyst for esterification using sulfonic containingmonomer through inverse suspension polymerization Theinfluence of several key factors for the polymer beads catalystability particle size and morphology such as the dispersantcrosslink agent porogen and preparing condition was inves-tigated The catalysis ability regarding the esterification ofacrylic acid and n-octanol was evaluated

2 Experiment

21Material Sodium p-styrene sulfonate (SSS) was obtainedfrom Shandong Star Alliance Biotechnology Co (Shan-dong China) NN1015840-methylenebisacrylamide (MBA) andp-hydroxyanisole were supplied by Tianjin Guangfu FineChemical Institute (Tianjin China) Persulfate liquid paraf-fin acrylic acid 119899-octanol span60 and tween60 werepurchased from Tianjin Fuchen Chemical Reagent Factory(Tianjin China) Propanediol n-butanol 14ndashbutanedioland polyethylene glycol (PEG200 PEG400 PEG600) weresupplied by Beijing Chemical Works (Beijing China) Allregents were of analytical grade and used without furtherpurification

22 Polymer Beads Characterization The Fourier transforminfrared spectra (FT-IR) were recorded on Nicolet 5700(Nicolet Instrument Thermo Company USA) Samples wereprepared with KBr powder and pressed into flake

The sulfonic group content was represented from the totalamount of sulfur as measured by elemental analysis (CHNSMode Elementar Analysensysteme GmbH Company Ger-man) through burnt polymer at high temperature

The titration was used to measure ion exchange capacityThe pretreated polymer beads with acid were dried by freeze-drying for a whole day and 40 mg beads were takensuspended in 10 mL deionized water and titrated with 01molL standard NaOH aqueous solution in the presence ofa phenolphthalein indicator [17ndash19]

Laser scattering particle size distribution analyzer(MalvernMastersizer 2000UK)was used tomeasure particlesize and size distribution of polymer beads with ethanol asdispersant Themedian particle size and microsphere surfacearea per unit volume (SPArea) were adopted to characterizethe particle size A larger median particle size and a smallerSPArea indicated the increase of particle size [20] Here inorder to better characterize the size distribution of copolymermicrospheres we referred to the knowledge of mathematicalstatistics and introduce the coefficient of variation (CV) as aparameter

CV = 120590120583 (1)

where 120590 is the sample standard deviation and 120583 is thearithmetic mean of particle size Coefficient of variation is

a statistic that can measure the variation extent of eachobserved variation and quantifies the width of the distri-bution function relative to its mean A larger coefficientof variation indicates that the distribution of the observedvariation is less concentrated [21]

23 Synthesis of Ion Polymer Beads The polymer beadswere prepared by the inverse suspension polymerizationmethod The monomer and crosslink agent mixture solutionwas prepared by fully dissolving 6 g sodium p-styrenesulfonate (SSS monomer) predetermined amount of NN1015840-methylenebisacrylamide (MBA crosslink agent) 024 g per-sulfate (initiator) 20 mL deionized water and differentporogen with 30 min ultrasound treatment Then 048 gdifferent dispersant and 75mL liquid paraffin (oil phase) wereadded to 250ml four-necked flask with mechanical stirrerand immersed in a thermostatically controlled heating unitwith temperature of 50∘C for 30 min until the oil phasewas fully melted Then the monomer and crosslink agentmixture solution was poured into 250 ml four-necked flaskequipped with mechanical stirring and reflux condenserunder vigor stirring to produce the inverse suspensionsystem At last the temperature was raised up to 90∘C andmaintained for 4 hours with agitation to perform polymer-ization After polymerization the polymer beads were filteredout and rinsed off three times with ethanol and deionizedwater separately to remove the unreacted materials anddried

The obtained beads were characterized by FT-IR Thecharacteristic peaks around 1184 cmminus1 (sulfonate group) 1041cmminus1 (benzene ring) 833 cmminus1 (14-disubstituted benzene)and 1655 cmminus1 (amide group) demonstrated the target prod-uct was successfully synthesized

24 Acidification and Esterification Evaluation ProcedureDifferent from the traditional complex process to change thepolymer beads into ion exchange resin through sulfonation[22] the sulfonic groups could form after just immersing thesynthesized polymer beads containing sulfonate groups intoconcentrated hydrochloric acid for 4 hours at room temper-ature in our study After the acidification the beads werepoured slowly into deionized water and washed by deionizedwater until the effluent was free of acid This is the pretreat-ment process of the synthesized resin beads Then the beadswere completely ready to begin the catalyzing evaluationprocedureThe esterification reaction was performed in four-necked round-bottomflask equippedwithmechanical stirrercondenser and water splitterThe flask was then immersed ina thermostatically controlled heating unit Acrylic acid and119899-octanol were added to the reactor with the weight ratio of171 accompanied with azeotropic solvent toluene inhibitor4-methoxyphenol (01 wt) and the polymer beads (5 wtin dry weight) after pretreatment and then the esterificationwas performed at the temperature of 110∘C for 5h After theexperiment the catalysts were filtered out from solution andwashed by acetone and deionizedwater three times separatelyto prepare for the next esterification

The esterification was traced by gas chromatographyDuring the reaction a series of 05 mL reaction solutions




Tween60Span60(ww)






119862119900119899V119890119903119904119894119900119899 =(11987811198721)

(11987811198721+ 11987821198722)lowast 100 (2)


1is the








200

400

600

800

1000

1200

1400

00110

00115

00120

00125

00130

00135

00140

Y1 Y2 Y3

Y2

SPA

rea (

cm2 g

)

Y3

CV



100

200

300

400

500

600

Y1M

edia

n siz

e (um

)







abc


0

10

20

30

40

50

60

)

(noisrevno

C







Crosslinkagent

(wt of SSS)

S (wt)Ion exchange

capacity(mmolg)







260m

(a)

2260m

(b)







450

500

550

600

650

700

750

800

00112

00113

00114

00115

00116

00117

Y1Y2Y3

Y2S

PA

rea (

cm2

g)

Y3C

V

250

300

350

400

450

Y1M

edia

n siz

e (um

)








C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC












P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)






400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







Tween60Span60(ww)






119862119900119899V119890119903119904119894119900119899 =(11987811198721)

(11987811198721+ 11987821198722)lowast 100 (2)


1is the








200

400

600

800

1000

1200

1400

00110

00115

00120

00125

00130

00135

00140

Y1 Y2 Y3

Y2

SPA

rea (

cm2 g

)

Y3

CV



100

200

300

400

500

600

Y1M

edia

n siz

e (um

)







abc


0

10

20

30

40

50

60

)

(noisrevno

C







Crosslinkagent

(wt of SSS)

S (wt)Ion exchange

capacity(mmolg)







260m

(a)

2260m

(b)







450

500

550

600

650

700

750

800

00112

00113

00114

00115

00116

00117

Y1Y2Y3

Y2S

PA

rea (

cm2

g)

Y3C

V

250

300

350

400

450

Y1M

edia

n siz

e (um

)








C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC












P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)






400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





abc


0

10

20

30

40

50

60

)

(noisrevno

C







Crosslinkagent

(wt of SSS)

S (wt)Ion exchange

capacity(mmolg)







260m

(a)

2260m

(b)







450

500

550

600

650

700

750

800

00112

00113

00114

00115

00116

00117

Y1Y2Y3

Y2S

PA

rea (

cm2

g)

Y3C

V

250

300

350

400

450

Y1M

edia

n siz

e (um

)








C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC












P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)






400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





260m

(a)

2260m

(b)







450

500

550

600

650

700

750

800

00112

00113

00114

00115

00116

00117

Y1Y2Y3

Y2S

PA

rea (

cm2

g)

Y3C

V

250

300

350

400

450

Y1M

edia

n siz

e (um

)








C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC












P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)






400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





C20-1C20-2C20-3

C20-4C20-5

0102030405060708090

100)

(noisrevnoC












P-10

10

20

30

40

50

60

70

80

90

100

max

imum

conv

ersio

n (

)






400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





400

450

500

550

600

Y1 Y2 Y3

Y2S

PA

rea (

m2 g

)


00114

00116

00118

00120

00122

00124

00126

Y1M

edia

n siz

e (um

)250

300

350

400

450

500

550

600

650

Y3C

V


(a)

(a)

(b)

(b)

(c)

(c)


4 Conclusions


Data Availability




Acknowledgments


References






































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




Documents

Sulfonic Containing Polymer Bead Synthesized through ...downloads.hindawi.com/journals/apt/2019/4854620.pdfwt%Tween(STb)system.esulfurelementratio can also be calculated from ion exchange