Methanol conversion to hydrocarbons over zeolite H-ZSM-5: Investigation of the role of CO and ketene in the formation of the initial C-C bond

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1234· OSTI ID:5602148

Hutchings, G J; Johnston, P ^[1]; Hunter, R ^[2]; Van Rensburg, L J ^[3]

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1. Univ. of Liverpool (United Kingdom)
2. Univ. of Cape Town, Rondesbosch (South Africa)
3. Univ. of Witwatersrand (South Africa)

Mechanistic studies concerning the formation of the initial carbon-carbon bond in the methanol conversion reaction over zeolite H-ZSM-5 are described and discussed. In particular, the possible roles of CO as a reaction intermediate or as a catalyst, via the formation of ketene, are evaluated. Experiments using [sup 13]CH[sub 3]OH/[sup 12]CO reactant mixtures demonstrate that no CO is incorporated into ethene, the primary product of this reaction. In addition, CO is found to have no significant effect on the induction period for this reaction. Model experiments for the methylation of ketene by reaction with Me[sub 2]SO[sub 4] and Me[sub 3]O[sup +]SbCl[sub 6][sup [minus]] did not provide evidence for methylation of ketene on either of the C atoms, and from the products observed it is apparent that ketene acts only as an acylating agent in the normal way. Experiments using aluminum silica compounds as models for the active site in the zeolite are described and discussed. Hydrogen/deuterium exchange experiments indicate that a common intermediate exists that can lead to the eventual formation of CH[sub 3]OCH[sub 3], CH[sub 4], and C[sub 2]H[sub 4]. Coreaction of CD[sub 3]OCD[sub 3] and CH[sub 3]OCH[sub 3] indicates that at least two intermediates are required for the formation of the ethene primary product. The results of this study indicate that CO and CH[sub 2]CO play no significant mechanistic role in the formation of the primary products of methanol conversion. A mechanism consistent with the experimental evidence available involving a surface bonded methoxy group is proposed and discussed. 33 refs., 8 figs., 5 tabs.

• OSTI ID: 5602148
• Journal Information: Journal of Catalysis; (United States), Vol. 142:2; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
01 COAL, LIGNITE, AND PEAT
10 SYNTHETIC FUELS
ETHYLENE
CHEMICAL PREPARATION
METHANOL
CONVERSION
ZEOLITES
CATALYTIC EFFECTS
CARBON 13
CARBON MONOXIDE
CATALYSTS
DEUTERIUM
HETEROGENEOUS CATALYSIS
HYDROCARBONS
HYDROGEN
KETENES
LABELLED COMPOUNDS
REACTION INTERMEDIATES
ALCOHOLS
ALKENES
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CATALYSIS
CHALCOGENIDES
ELEMENTS
EVEN-ODD NUCLEI
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
LIGHT NUCLEI
MATERIALS
MINERALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SILICATE MINERALS
STABLE ISOTOPES
SYNTHESIS
400201* - Chemical & Physicochemical Properties
010408 - Coal
Lignite
& Peat- C1 Processes- (1987-)
100200 - Synthetic Fuels- Production- (1990-)