Ethylbenzene disproportionation and p-xylene selectivity enhancement in xylene isomerization using high crystallinity desilicated H-ZSM-5  

作　　者：Marjan Farshadi Cavus Falamaki 

机构地区：[1]Chemical Engineering Department,Mahshahr Campus,Amirkabir University of Technology,Mahshahr 415,Iran [2]Chemical Engneering Department,Amirkabir University of Technology,Tehran 15875-4413.Iran [3]Petrochemical Center of Excellence,Amirkabir University of Technology,Tehran 15875-4413,Iran

出　　处：《Chinese Journal of Chemical Engineering》2018年第1期116-126,共11页中国化学工程学报（英文版）

基　　金：financed by BIPC,Mahshahr,Iran under the contract number 08-133/57665

摘　　要：Desilication accompanied with minimum loss of crystallinity effect of a high alumina ZSM-5 zeolite on the isomerization reaction of ethylbenzene/xylene mixtures has been considered.Desilication was assessed through XRF,XRD,FTIR,TEM,nitrogen adsorption/desorption,NH_3-TPD,^(29)Si and^(27)Al MAS NMR analytical techniques.Desilication was accompanied with the creation of super acid sites.There exists a limit(Si/Al molar ratio of9.67)for keeping high crystallinity and obtaining improved catalytic performance.Desilication promotes ethylbenzene conversion by disproportionation and trans-alkylation reactions while the same reactions are limited for the xylene isomers.The p-xylene approach to equilibrium improves by more than 7% at 400℃ and a WHSV of 2 h^(-1)for the optimum sample with respect to the parent zeolite.At the same conditions,the optimum sample exhibits the maximum ethylbenzene conversion of 89%,i.e.more than 40%w.r.t.of the parent zeolite.However,the xylene yield decreases only 3%.Desilication accompanied with minimum loss of crystallinity effect of a high alumina ZSM-5 zeolite on the isomerization reaction ofethylbenzene/xylene mixtures has been considered. Desilication was assessed through XRF, XRD, FTIR, TEM, nitrogen adsorption/desorption, NH3-TPD, 29Si and 27Al MAS NMR analytical techniques. Desilication was accompanied with the creation of super acid sites. There exists a limit （Si/Al molar ratio of 9.67） for keeping high crystallinity and obtaining improved catalytic performance. Desilication promotes ethylbenzene conversion by disproportionation and trans-alkylation reactions while the same reactions are limited for the xylene isomers. The p-xylene approach to equilibrium improves by more than 7% at 400 ℃ and a WHSV of 2 h- 1 for the optimum sample with respect to the parent zeolite. At the same conditions, the optimum sample exhibits the maximum ethylbenzene conversion of 89%, i.e. more than 40% w.r.t, of the parent zeolite. However, the xylene yield decreases only 3%.

关 键 词：Zeolite Catalyst Kinetics Xylene isomerizatioo ZSM-5 zeolite Desilication 

分 类 号：TQ241.13[化学工程—有机化工]