Reaction mechanism of methylation of 4-methylbiphenyl with methanol over H-ZSM-5 zeolite

Ling Ling Li, Michael J. Janik, Xiao Wa Nie, Chun Shan Song, Xin Wen Guo

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The methylation of 4-methylbiphenyl (4-MBP) can yield 4,4'-dimethylbiphenyl (4,4'-DMBP), an important precursor for advanced polymers. The reaction mechanismof the shape-selective methylation of 4-MBP with methanol within the pores of H-ZSM-5 zeolite was studied, using“our own-N-layered integrated molecular orbital+molecular mechanics”(ONIOM) and density functional theory (DFT) methods. Stepwise and concerted mechanisms were considered, with the former having a lower activation energy. 4,4'-DMBPis kinetically favored by both mechanisms. Transition state selectivity accounts for the preferential methylation to 4,4'-DMBP. The isomerization of 4-MBPto 3-methylbiphenyl (3-MBP) is restricted within the zeolite. The isomerization of 4-MBP to 3-MBPis kinetically favored over methylation on the external zeolite surface, which causes a decrease in 4, 4'-DMBP selectivity. Passivating the external surface will suppress 4-MBP isomerization, therefore increasing 4,4'-DMBP selectivity by restricting reaction within the zeolite. The computational results of shape-selective and non-selective reactions over H-ZSM-5 zeolite well account for the experimental observations.

Original languageEnglish (US)
Pages (from-to)56-66
Number of pages11
JournalWuli Huaxue Xuebao/ Acta Physico - Chimica Sinica
Volume31
Issue number1
DOIs
StatePublished - 2015

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Fingerprint Dive into the research topics of 'Reaction mechanism of methylation of 4-methylbiphenyl with methanol over H-ZSM-5 zeolite'. Together they form a unique fingerprint.

  • Cite this