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

Ling Ling Li, Michael John Janik, Xiao Wa Nie, Chunshan Song, Xin Wen Guo

Research output: Contribution to journalArticle

2 Citations (Scopus)

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 - Jan 1 2015

Fingerprint

methylation
Methylation
Zeolites
Methanol
methyl alcohol
Isomerization
isomerization
selectivity
Molecular mechanics
Molecular orbitals
Density functional theory
molecular orbitals
Polymers
Activation energy
activation energy
density functional theory
porosity
ZSM-5 zeolite
causes
polymers

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

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title = "Reaction mechanism of methylation of 4-methylbiphenyl with methanol over H-ZSM-5 zeolite",
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.",
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Reaction mechanism of methylation of 4-methylbiphenyl with methanol over H-ZSM-5 zeolite. / Li, Ling Ling; Janik, Michael John; Nie, Xiao Wa; Song, Chunshan; Guo, Xin Wen.

In: Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica, Vol. 31, No. 1, 01.01.2015, p. 56-66.

Research output: Contribution to journalArticle

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AU - Li, Ling Ling

AU - Janik, Michael John

AU - Nie, Xiao Wa

AU - Song, Chunshan

AU - Guo, Xin Wen

PY - 2015/1/1

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N2 - 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.

AB - 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.

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