A theoretical investigation into the thiophene-cracking mechanism over pure Bronsted acidic zeolites

Journal Article · Tue Jan 15 04:00:00 EST 2008 · Journal of Catalysis

DOI:https://doi.org/10.1016/j.jcat.2007.10.006· OSTI ID:21073787

Li, B R; Guo, W P; Yuan, S P; Hu, J; Wang, J G; Hao, H J ^[1]

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1. Chinese Academy of Science, Taiyuan (China)

The mechanism of thiophene cracking catalyzed by Bronsted acidic zeolites was computed at the level of B3LYP density functional theory. It was found that this catalytic reaction involves two major steps: (1) protonation of thiophene associated with an electrophilic aromatic substitution to another thiophene in a concerted way to form 2-(2,5-dihydrothiophen-2-yl) thiophene, and (2) C-S bond dissociation in 2,5-dihydrothiophene promoted by further protonation. The intermediate, 4-mercapto-1-(thiophen-2-yl)but-2-en-1-ylium, was found to have a CH{sub 2} group close to a C=C bond and a SH group, in agreement with the experimental findings. A strong stabilization effect of the zeolite framework on the transition states was found by embedding the 5T cluster into the larger 34T and 56T clusters. The rate-determining step is the electrophilic aromatic substitution.

• OSTI ID: 21073787
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 253; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CATALYTIC CRACKING
CHEMICAL REACTION KINETICS
REACTION INTERMEDIATES
THIOPHENE
ZEOLITES