On the reaction mechanism for hydrocarbon formation from methanol over SAPO-34: 1. Isotopic labeling studies of the Co-reaction of ethene and methanol
- Univ. of Oslo (Norway)
{sup 13}C-Methanol and {sup 12}C-ethene (fed as ethanol) have been co-reacted over SAPO-34 in a flow system at 400{degrees}C using argon as a carrier (diluent) gas. The feed contained an equal number of {sup 13}C and {sup 12}C atoms. The products were analyzed by GC-MS, allowing the determination of the isotopic composition of the reactor effluent. The ethanol was immediately converted to ethene, so the reaction system was equivalent to a feed consisting of methanol/ethene/water. While the methanol was completely or almost completely converted to hydrocarbons, the larger part of the ethene emerged unreacted. The products propene and butenes were mostly formed from methanol and contained a large excess of {sup 13}C atoms. The ethene effluent consisted mainly of all {sup 12}C or all {sup 13}C atoms, and only to a small extent of {sup 12}C-{sup 13}C molecules. The reaction system was followed from an initially very active catalyst until the catalyst was sufficiently deactivated that C{sub 1} was not completely converted to hydrocarbons. The tendency for ethene to emerge unreacted, and for all new hydrocarbons to be formed from methanol became more pronounced with progressing catalyst deactivation. The results show clearly that the higher hydrocarbons are, over this catalyst, not formed by successive methylations of ethene. A previously proposed {open_quotes}carbon pool{close_quotes} mechanism can explain the gross effects seen in the product and isotopic distribution. 15 refs., 6 figs., 4 tabs.
- OSTI ID:
- 98937
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 149; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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