TITLE: Study of Fischer-Tropsch Synthesis Through the Use of Surface Intermediate Scavengers. Progress Report, August 1, 1982-April 1, 1983.

AUTHOR: J. G. Ekerdt.

INST.  AUTHOR: Texas Univ. at Austin.

SPONSOR: Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1983,  60p.


The primary goal of the research is to identify the reaction pathways by which synthesis gas is converted into hydrocarbons. These mechanisms are needed to understand the fundamental causes for selectivity and to develop more selective catalysts from first principles. The actual effort was directed toward studies of Fischer-Tropsch synthesis over Fe/SiO sub 2 and isosynthesis catalytic chemistry over ZrO sub 2 . Fischer-Tropsch synthesis studies concentrated upon the propagation reaction and the role alkyl species have in propagation and termination. Alkyl species concentrations were inferred by scavenging the alkyl species off the surface during Fischer-Tropsch synthesis. Pyridine was used as the scavenger and C sub 1 -C sub 4 - alpha -Alkylpyridines were formed. The distributions of the alkylpyridines were studied as a function of the synthesis conditions. These studies established that alkyl fragments are the precursor to gas phase products and that alkyl fragments are participating in the propagation reaction. The details of the propagation reaction, methylene versus CO insertion, could be determined. Isosynthesis studies concentrated upon the reaction pathway to iso-C sub 4 products and the initiation of the reaction. Rate measurements at 37 atm suggest that isobutene is formed in a stepwise process between a C sub 3 carbenium ion and a C sub 1 oxygenaged species. Studies at 1 atm suggest that CO adsorbs and interacts with surface hydroxyl groups to form formates, carbonates and methoxides. The methoxide may be the C sub 1 species participating in C sub 4 formation. 9 figures, 6 tables. (ERA citation 08:029287)