SCI和EI收录∣中国化工学会会刊

Chin.J.Chem.Eng. ›› 2018, Vol. 26 ›› Issue (1): 116-126.DOI: 10.1016/j.cjche.2017.03.023

• Catalysis, Kinetics and Reaction Engineering • Previous Articles     Next Articles

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

Marjan Farshadi1, Cavus Falamaki1,2,3   

  1. 1 Chemical Engineering Department, Mahshahr Campus, Amirkabir University of Technology, Mahshahr 415, Iran;
    2 Chemical Engineering Department, Amirkabir University of Technology, Tehran 15875-4413, Iran;
    3 Petrochemical Center of Excellence, Amirkabir University of Technology, Tehran 15875-4413, Iran
  • Received:2017-02-10 Revised:2017-03-20 Online:2018-03-01 Published:2018-01-28
  • Contact: Cavus Falamaki,E-mail address:c.falamaki@aut.ac.ir

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

Marjan Farshadi1, Cavus Falamaki1,2,3   

  1. 1 Chemical Engineering Department, Mahshahr Campus, Amirkabir University of Technology, Mahshahr 415, Iran;
    2 Chemical Engineering Department, Amirkabir University of Technology, Tehran 15875-4413, Iran;
    3 Petrochemical Center of Excellence, Amirkabir University of Technology, Tehran 15875-4413, Iran
  • 通讯作者: Cavus Falamaki,E-mail address:c.falamaki@aut.ac.ir

Abstract: 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, 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%.

Key words: Zeolite, Catalyst, Kinetics, Xylene isomerization, ZSM-5 zeolite, Desilication

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, 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 isomerization, ZSM-5 zeolite, Desilication