skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study

Abstract

The reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite was studied theoretically with periodic density functional theory calculations including dispersion forces and experimentally in a fixed bed flow reactor at pressures between 10 and 100 bar, dimethyl ether concentrations in CO between 0.2 and 2.0%, and at a temperature of 438 K. The theoretical study showed that the reaction of CO with surface methyl groups, the rate-limiting step, is faster in the eight-membered side pockets than in the twelve-membered main channel of the zeolite; the subsequent reaction of dimethyl ether with surface acetyl to form methyl acetate was demonstrated to occur with low energy barriers in both the side pockets and in the main channel. Here, the present analysis has thus identified a path, where the entire reaction occurs favourably on a single site within the side pocket, in good agreement with previous experimental studies. The experimental study of the reaction kinetics was consistent with the theoretically derived mechanism and in addition revealed that the methyl acetate product inhibits the reaction – possibly by sterically hindering the attack of CO on the methyl groups in the side pockets.

Authors:
 [1];  [1];  [2];  [3];  [2];  [4];  [5]; ORCiD logo [1]
  1. Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical and Biochemical Engineering
  2. Haldor Topsoe A/S, Lyngby (Denmark)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States). SUNCAT Center for Interface Science and Catalysis
  4. Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Physics
  5. Technical Univ. of Denmark, Lyngby (Denmark). Centre for Catalysis and Sustainable Chemistry, Dept. of Chemistry
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1353213
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Catalysis Science and Technology
Additional Journal Information:
Journal Volume: 7; Journal Issue: 5; Journal ID: ISSN 2044-4753
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Rasmussen, D. B., Christensen, J. M., Temel, B., Studt, F., Moses, P. G., Rossmeisl, J., Riisager, A., and Jensen, A. D.. Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study. United States: N. p., 2017. Web. doi:10.1039/c6cy01904h.
Rasmussen, D. B., Christensen, J. M., Temel, B., Studt, F., Moses, P. G., Rossmeisl, J., Riisager, A., & Jensen, A. D.. Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study. United States. doi:10.1039/c6cy01904h.
Rasmussen, D. B., Christensen, J. M., Temel, B., Studt, F., Moses, P. G., Rossmeisl, J., Riisager, A., and Jensen, A. D.. Mon . "Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study". United States. doi:10.1039/c6cy01904h. https://www.osti.gov/servlets/purl/1353213.
@article{osti_1353213,
title = {Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study},
author = {Rasmussen, D. B. and Christensen, J. M. and Temel, B. and Studt, F. and Moses, P. G. and Rossmeisl, J. and Riisager, A. and Jensen, A. D.},
abstractNote = {The reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite was studied theoretically with periodic density functional theory calculations including dispersion forces and experimentally in a fixed bed flow reactor at pressures between 10 and 100 bar, dimethyl ether concentrations in CO between 0.2 and 2.0%, and at a temperature of 438 K. The theoretical study showed that the reaction of CO with surface methyl groups, the rate-limiting step, is faster in the eight-membered side pockets than in the twelve-membered main channel of the zeolite; the subsequent reaction of dimethyl ether with surface acetyl to form methyl acetate was demonstrated to occur with low energy barriers in both the side pockets and in the main channel. Here, the present analysis has thus identified a path, where the entire reaction occurs favourably on a single site within the side pocket, in good agreement with previous experimental studies. The experimental study of the reaction kinetics was consistent with the theoretically derived mechanism and in addition revealed that the methyl acetate product inhibits the reaction – possibly by sterically hindering the attack of CO on the methyl groups in the side pockets.},
doi = {10.1039/c6cy01904h},
journal = {Catalysis Science and Technology},
number = 5,
volume = 7,
place = {United States},
year = {Mon Jan 23 00:00:00 EST 2017},
month = {Mon Jan 23 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:
  • The synthesis of acetic acid (AcOH) from methanol (MeOH) and carbon monoxide has been performed industrially in the liquid phase using a rhodium complex catalyst and an iodide promoter. The selectivity to AcOH is more than 99% under mild conditions (175/sup 0/C, 28 atm). The homogeneous rhodium catalyst has been also effective for the synthesis of acetic anhydride (Ac/sub 2/O) by carbonylation of dimethyl ether (DME) or methyl acetate (AcOMe). However, rhodium is one of the most expensive metals and its proved reserves are quite limited. It is highly desired, therefore, to develop a new catalyst as a substitute formore » rhodium. The authors have already reported that nickel supported on active carbon exhibits an excellent activity for the vapor phase carbonylation of MeOh in the presence of iodide promoter and under moderately pressurized conditions. In addition, corrosive attack on reactors by iodide compounds is expected to be negligible in the vapor phase system. In the present work, vapor phase carbonylation of DME and AcOMe on nickel-active carbon (Ni/A.C.) and molybdenum-active carbon (Mo/A.C.) catalysts was studied.« less
  • Oxidative carbonylation of methanol to dimethyl carbonate in the presence of Cu-Y zeolite was studied. The mechanism of the process was elucidated. 15 refs., 16 figs., 1 tab.
  • The aim of this work was to establish the effects of zeolite structure/chemical composition on the activity and selectivity of Cu-exchanged Y (Si/Al = 2.5), ZSM-5 (Si/Al = 12), and Mordenite (Si/Al = 10) for the oxidative carbonylation of methanol to DMC. Catalysts were prepared by solid-state ion-exchange of the H-form of each zeolite with CuCl and were then characterized by FTIR and X-ray absorption spectroscopy (XAS). The XANES portion of the XAS data showed that all of the copper was present as Cu{sup +} cations, and analysis of the EXAFS portion of the data shows the Cu{sup +} cationsmore » had a CuO coordination number of 2.1 on Cu-Y and 2.7 on Cu-ZSM-5 and Cu-MOR. Dimethyl carbonate (DMC) was observed as the primary product when a mixture of CH{sub 3}OH/CO/O{sub 2} was passed over Cu-Y, whereas dimethoxy methane was the primary product over Cu-ZSM-5 and Cu-MOR. The higher activity and selectivity of Cu-Y for the oxidative carbonylation of methanol can be attributed to the weaker adsorption of CO on the Cu{sup +} cations exchanged into Y zeolite. In situ IR observations revealed that under reaction conditions, adsorbed CO was displaced by methoxide groups bound to the Cu{sup +} cations. The kinetics of DMC synthesis suggests that the rate-limiting step in the formation of this product was the insertion of CO into CuOCH{sub 3} bonds. The yield of DMC decreased with methanol conversion, likely due to the hydrolysis of DMC to methanol and carbon dioxide.« less
  • The oxidation mechanism of dimethyl ether is investigated using ab initio methods. The structure and energetics of reactants, products, and transition structures are determined for all pathways involved in the oxidation mechanism. The detailed pathways leading to the experimentally observed products of dimethyl ether oxidation are presented. The energetics of over 50 species and transition structures involved in the oxidation process are calculated with G2 and G2(MP2) energies. The principal pathway following the initial attack of dimethyl ether (CH{sub 3}OCH{sub 3}) by the OH radical is the formation of the methoxymethyl radical (CH{sub 2}OCH{sub 3}). Oxidation steps lead to themore » formation of methyl formate, which is consistent with the experimentally observed products. Oxidation pathways of methyl formate are also considered.« less