TITLE: Effect of 1-alkene addition on hydrocarbon product distribution in Fischer-Tropsch synthesis on a cobalt catalyst.

AUTHOR: I. C. Yates;   C. N. Satterfield.

INST.  AUTHOR: Massachusetts Inst. of Tech., Cambridge. Dept. of Chemical Engineering.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  Jul 91,  37p.

NTIS ORDER NO.: DE91018705INW

ABSTRACT:

The cobalt-catalyzed reactions of C(sub 2)H(sub 4), C(sub 3)H(sub 6), or 1-C(sub 4)H(sub 8) added to synthesis gas in concentrations ranging from 0.5 to 1.2 mol. % of total feed were studied at 220(degrees)C, and 0.45 to 1.48 MPa. H(sub 2)/CO feed ratios were varied between 1.45 to 2.25 and H(sub 2) + CO conversions between 5 and 30% were observed. 1-Alkenes incorporate into growing chains on the catalyst surface, probably by initiating and/or terminating the chain growth process. Only ethene may propagate chain growth significantly. The propensity of the 1-alkenes to incorporate decreases with increasing carbon number of the 1-alkene and is affected by the extent of competitive reactions, notably hydrogenation to the alkene and isomerization to the 2-alkene. Incorporation is most evident in products above about C(sub 10)+. The double-(alpha) behavior exhibited by most Fischer-Tropsch catalysts can be interpreted as the sum of two growth processes, one a stepwise single-carbon growth process and the other a 1-alkene incorporation process. Many of the effects of process variables on the hydrocarbon selectivity of Fischer-Tropsch catalysts are consistent with this theory. 14 refs., 10 figs., 1 tab.

REPORT  NUMBER: DOE/PC/79816-T2

CONTRACT  NUMBER: AC22-87PC79816