Shape-selective methylation of 2-methylnaphthalene with methanol over H-ZSM-5 zeolite: A computational study

Xiaowa Nie, Michael John Janik, Xinwen Guo, Chunshan Song

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Methylation of 2-methylnaphthalene (2-MN) for synthesis of 2,6-dimethylnaphthalene (2,6-DMN) is an industrially important reaction because 2,6-DMN is a key precursor for the advanced polymer material polyethylenenaphthalate. Shape-selective methylation of 2-MN with methanol in an H-ZSM-5 pore was studied using the ONIOM2 model and density functional theory. Two proposed reaction mechanisms, stepwise and concerted, were considered. Computational results reveal that the stepwise path, with methanol dehydration to produce a methoxide intermediate as the rate-limiting step, is kinetically favored. Both the stepwise and concerted path indicated that methylation at the 6-position is favored over methylation at the 7-position; however, the concerted path shows a greater selectivity. 2-MN isomerization and methylation, which may occur on the catalyst external surface and decrease selectivity to the desired 2,6-DMN product were also examined. Isomerization of 2-MN to 1-MN proceeds faster on external surface sites than 2-MN methylation with methanol. Decreasing the external surface acid site concentration will restrict the extent of 2-MN isomerization, therefore increasing the β,β′-DMN selectivity inside the pore.

Original languageEnglish (US)
Pages (from-to)4071-4082
Number of pages12
JournalJournal of Physical Chemistry C
Volume116
Issue number6
DOIs
StatePublished - Feb 16 2012

Fingerprint

methylation
Methylation
Methanol
methyl alcohol
Isomerization
isomerization
selectivity
porosity
Catalyst selectivity
Dehydration
dehydration
Density functional theory
2-methylnaphthalene
ZSM-5 zeolite
Polymers
density functional theory
catalysts
acids
Catalysts
Acids

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

@article{d622594df6234e6d84ba5b2430cf6c97,
title = "Shape-selective methylation of 2-methylnaphthalene with methanol over H-ZSM-5 zeolite: A computational study",
abstract = "Methylation of 2-methylnaphthalene (2-MN) for synthesis of 2,6-dimethylnaphthalene (2,6-DMN) is an industrially important reaction because 2,6-DMN is a key precursor for the advanced polymer material polyethylenenaphthalate. Shape-selective methylation of 2-MN with methanol in an H-ZSM-5 pore was studied using the ONIOM2 model and density functional theory. Two proposed reaction mechanisms, stepwise and concerted, were considered. Computational results reveal that the stepwise path, with methanol dehydration to produce a methoxide intermediate as the rate-limiting step, is kinetically favored. Both the stepwise and concerted path indicated that methylation at the 6-position is favored over methylation at the 7-position; however, the concerted path shows a greater selectivity. 2-MN isomerization and methylation, which may occur on the catalyst external surface and decrease selectivity to the desired 2,6-DMN product were also examined. Isomerization of 2-MN to 1-MN proceeds faster on external surface sites than 2-MN methylation with methanol. Decreasing the external surface acid site concentration will restrict the extent of 2-MN isomerization, therefore increasing the β,β′-DMN selectivity inside the pore.",
author = "Xiaowa Nie and Janik, {Michael John} and Xinwen Guo and Chunshan Song",
year = "2012",
month = "2",
day = "16",
doi = "10.1021/jp209337m",
language = "English (US)",
volume = "116",
pages = "4071--4082",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "6",

}

Shape-selective methylation of 2-methylnaphthalene with methanol over H-ZSM-5 zeolite : A computational study. / Nie, Xiaowa; Janik, Michael John; Guo, Xinwen; Song, Chunshan.

In: Journal of Physical Chemistry C, Vol. 116, No. 6, 16.02.2012, p. 4071-4082.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Shape-selective methylation of 2-methylnaphthalene with methanol over H-ZSM-5 zeolite

T2 - A computational study

AU - Nie, Xiaowa

AU - Janik, Michael John

AU - Guo, Xinwen

AU - Song, Chunshan

PY - 2012/2/16

Y1 - 2012/2/16

N2 - Methylation of 2-methylnaphthalene (2-MN) for synthesis of 2,6-dimethylnaphthalene (2,6-DMN) is an industrially important reaction because 2,6-DMN is a key precursor for the advanced polymer material polyethylenenaphthalate. Shape-selective methylation of 2-MN with methanol in an H-ZSM-5 pore was studied using the ONIOM2 model and density functional theory. Two proposed reaction mechanisms, stepwise and concerted, were considered. Computational results reveal that the stepwise path, with methanol dehydration to produce a methoxide intermediate as the rate-limiting step, is kinetically favored. Both the stepwise and concerted path indicated that methylation at the 6-position is favored over methylation at the 7-position; however, the concerted path shows a greater selectivity. 2-MN isomerization and methylation, which may occur on the catalyst external surface and decrease selectivity to the desired 2,6-DMN product were also examined. Isomerization of 2-MN to 1-MN proceeds faster on external surface sites than 2-MN methylation with methanol. Decreasing the external surface acid site concentration will restrict the extent of 2-MN isomerization, therefore increasing the β,β′-DMN selectivity inside the pore.

AB - Methylation of 2-methylnaphthalene (2-MN) for synthesis of 2,6-dimethylnaphthalene (2,6-DMN) is an industrially important reaction because 2,6-DMN is a key precursor for the advanced polymer material polyethylenenaphthalate. Shape-selective methylation of 2-MN with methanol in an H-ZSM-5 pore was studied using the ONIOM2 model and density functional theory. Two proposed reaction mechanisms, stepwise and concerted, were considered. Computational results reveal that the stepwise path, with methanol dehydration to produce a methoxide intermediate as the rate-limiting step, is kinetically favored. Both the stepwise and concerted path indicated that methylation at the 6-position is favored over methylation at the 7-position; however, the concerted path shows a greater selectivity. 2-MN isomerization and methylation, which may occur on the catalyst external surface and decrease selectivity to the desired 2,6-DMN product were also examined. Isomerization of 2-MN to 1-MN proceeds faster on external surface sites than 2-MN methylation with methanol. Decreasing the external surface acid site concentration will restrict the extent of 2-MN isomerization, therefore increasing the β,β′-DMN selectivity inside the pore.

UR - http://www.scopus.com/inward/record.url?scp=84857401658&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84857401658&partnerID=8YFLogxK

U2 - 10.1021/jp209337m

DO - 10.1021/jp209337m

M3 - Article

AN - SCOPUS:84857401658

VL - 116

SP - 4071

EP - 4082

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 6

ER -