Alkyl chain propagation by methylene insertion on Cu(100)

Jong-Liang Lin, Chao Ming Chiang, Cynthia J. Jenks, Michael X. Yang, Tim H. Wentzlaff, Brian E. Bent

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

One of the mechanisms proposed for formation of carboncarbon bonds in the Fischer-Tropsch synthesis, the so-called carbide/methylene mechanism, involves the propagation of alkyl chains on the catalyst surface by methylene insertion. The studies reported here provide evidence for this reaction on single crystal copper surfaces under ultra-high vacuum conditions. Alkyl iodides are used as molecular precursors to generate adsorbed methylene and alkyl groups on a Cu(100) surface. High-resolution electron energy loss spectroscopy and work function change measurements show that CI bond dissociation occurs below 200 K in iodoalkanes to form alkyl groups on the surface. Indirect evidence supports the formation of adsorbed methylene groups via CH2I2 dissociation. Temperature-programmed reaction studies of the CH2 + CD3 reaction show that sequential CH2 insertion followed by β-hydride elimination produces ethylene-d2 and propylene-d3. Similarly, reaction of CH2 with C2D5 produces propylene-d4. All of these reactions are extremely facile, occurring at 230-250 K with activation energies of 12-20 kcal/mol. Similar studies on Cu(110) show that the methylene insertion reaction is structure sensitive, being approximately two orders of magnitude faster on Cu(100) than on Cu(110). The source of this difference appears to be slow diffusion of methylene across the corrugated Cu(110) surface.

Original languageEnglish
Pages (from-to)250-263
Number of pages14
JournalJournal of Catalysis
Volume147
Issue number1
DOIs
Publication statusPublished - 1994 Jan 1

Fingerprint

methylene
insertion
propagation
Propylene
propylene
Fischer-Tropsch synthesis
dissociation
Electron energy loss spectroscopy
Ultrahigh vacuum
Iodides
Hydrides
Carbides
Copper
Ethylene
carbides
iodides
Activation energy
ultrahigh vacuum
hydrides
Single crystals

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Physical and Theoretical Chemistry

Cite this

Lin, J-L., Chiang, C. M., Jenks, C. J., Yang, M. X., Wentzlaff, T. H., & Bent, B. E. (1994). Alkyl chain propagation by methylene insertion on Cu(100). Journal of Catalysis, 147(1), 250-263. https://doi.org/10.1006/jcat.1994.1136
Lin, Jong-Liang ; Chiang, Chao Ming ; Jenks, Cynthia J. ; Yang, Michael X. ; Wentzlaff, Tim H. ; Bent, Brian E. / Alkyl chain propagation by methylene insertion on Cu(100). In: Journal of Catalysis. 1994 ; Vol. 147, No. 1. pp. 250-263.
@article{696fec5af2b541cc9e6ff19720a135bc,
title = "Alkyl chain propagation by methylene insertion on Cu(100)",
abstract = "One of the mechanisms proposed for formation of carboncarbon bonds in the Fischer-Tropsch synthesis, the so-called carbide/methylene mechanism, involves the propagation of alkyl chains on the catalyst surface by methylene insertion. The studies reported here provide evidence for this reaction on single crystal copper surfaces under ultra-high vacuum conditions. Alkyl iodides are used as molecular precursors to generate adsorbed methylene and alkyl groups on a Cu(100) surface. High-resolution electron energy loss spectroscopy and work function change measurements show that CI bond dissociation occurs below 200 K in iodoalkanes to form alkyl groups on the surface. Indirect evidence supports the formation of adsorbed methylene groups via CH2I2 dissociation. Temperature-programmed reaction studies of the CH2 + CD3 reaction show that sequential CH2 insertion followed by β-hydride elimination produces ethylene-d2 and propylene-d3. Similarly, reaction of CH2 with C2D5 produces propylene-d4. All of these reactions are extremely facile, occurring at 230-250 K with activation energies of 12-20 kcal/mol. Similar studies on Cu(110) show that the methylene insertion reaction is structure sensitive, being approximately two orders of magnitude faster on Cu(100) than on Cu(110). The source of this difference appears to be slow diffusion of methylene across the corrugated Cu(110) surface.",
author = "Jong-Liang Lin and Chiang, {Chao Ming} and Jenks, {Cynthia J.} and Yang, {Michael X.} and Wentzlaff, {Tim H.} and Bent, {Brian E.}",
year = "1994",
month = "1",
day = "1",
doi = "10.1006/jcat.1994.1136",
language = "English",
volume = "147",
pages = "250--263",
journal = "Journal of Catalysis",
issn = "0021-9517",
publisher = "Academic Press Inc.",
number = "1",

}

Lin, J-L, Chiang, CM, Jenks, CJ, Yang, MX, Wentzlaff, TH & Bent, BE 1994, 'Alkyl chain propagation by methylene insertion on Cu(100)', Journal of Catalysis, vol. 147, no. 1, pp. 250-263. https://doi.org/10.1006/jcat.1994.1136

Alkyl chain propagation by methylene insertion on Cu(100). / Lin, Jong-Liang; Chiang, Chao Ming; Jenks, Cynthia J.; Yang, Michael X.; Wentzlaff, Tim H.; Bent, Brian E.

In: Journal of Catalysis, Vol. 147, No. 1, 01.01.1994, p. 250-263.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Alkyl chain propagation by methylene insertion on Cu(100)

AU - Lin, Jong-Liang

AU - Chiang, Chao Ming

AU - Jenks, Cynthia J.

AU - Yang, Michael X.

AU - Wentzlaff, Tim H.

AU - Bent, Brian E.

PY - 1994/1/1

Y1 - 1994/1/1

N2 - One of the mechanisms proposed for formation of carboncarbon bonds in the Fischer-Tropsch synthesis, the so-called carbide/methylene mechanism, involves the propagation of alkyl chains on the catalyst surface by methylene insertion. The studies reported here provide evidence for this reaction on single crystal copper surfaces under ultra-high vacuum conditions. Alkyl iodides are used as molecular precursors to generate adsorbed methylene and alkyl groups on a Cu(100) surface. High-resolution electron energy loss spectroscopy and work function change measurements show that CI bond dissociation occurs below 200 K in iodoalkanes to form alkyl groups on the surface. Indirect evidence supports the formation of adsorbed methylene groups via CH2I2 dissociation. Temperature-programmed reaction studies of the CH2 + CD3 reaction show that sequential CH2 insertion followed by β-hydride elimination produces ethylene-d2 and propylene-d3. Similarly, reaction of CH2 with C2D5 produces propylene-d4. All of these reactions are extremely facile, occurring at 230-250 K with activation energies of 12-20 kcal/mol. Similar studies on Cu(110) show that the methylene insertion reaction is structure sensitive, being approximately two orders of magnitude faster on Cu(100) than on Cu(110). The source of this difference appears to be slow diffusion of methylene across the corrugated Cu(110) surface.

AB - One of the mechanisms proposed for formation of carboncarbon bonds in the Fischer-Tropsch synthesis, the so-called carbide/methylene mechanism, involves the propagation of alkyl chains on the catalyst surface by methylene insertion. The studies reported here provide evidence for this reaction on single crystal copper surfaces under ultra-high vacuum conditions. Alkyl iodides are used as molecular precursors to generate adsorbed methylene and alkyl groups on a Cu(100) surface. High-resolution electron energy loss spectroscopy and work function change measurements show that CI bond dissociation occurs below 200 K in iodoalkanes to form alkyl groups on the surface. Indirect evidence supports the formation of adsorbed methylene groups via CH2I2 dissociation. Temperature-programmed reaction studies of the CH2 + CD3 reaction show that sequential CH2 insertion followed by β-hydride elimination produces ethylene-d2 and propylene-d3. Similarly, reaction of CH2 with C2D5 produces propylene-d4. All of these reactions are extremely facile, occurring at 230-250 K with activation energies of 12-20 kcal/mol. Similar studies on Cu(110) show that the methylene insertion reaction is structure sensitive, being approximately two orders of magnitude faster on Cu(100) than on Cu(110). The source of this difference appears to be slow diffusion of methylene across the corrugated Cu(110) surface.

UR - http://www.scopus.com/inward/record.url?scp=0000080241&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000080241&partnerID=8YFLogxK

U2 - 10.1006/jcat.1994.1136

DO - 10.1006/jcat.1994.1136

M3 - Article

VL - 147

SP - 250

EP - 263

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

IS - 1

ER -

Lin J-L, Chiang CM, Jenks CJ, Yang MX, Wentzlaff TH, Bent BE. Alkyl chain propagation by methylene insertion on Cu(100). Journal of Catalysis. 1994 Jan 1;147(1):250-263. https://doi.org/10.1006/jcat.1994.1136