TITLE: Study of the Catalytic Conversion of Synthesis Gas to Low-Molecular Weight Hydrocarbons.

AUTHOR: T. Y. Chan.

INST.  AUTHOR: Texas A and M Univ., College Station. Dept. of Chemical Engineering.

SPONSOR: Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  Aug 81,  112p.


The search for alternative sources of energy has provided the stage for the examination of catalytic reactions which can influence the supply of low molecular weight chemical feedstocks, such as ethylene, propylene, and butadiene. Synthesis gas produced from partial oxidation of coal is considered the basic building block for all alternative chemical feedstock synthesis. However, the classical Fischer-Tropsch synthesis catalysts exhibit poor selectivity toward low molecular weight hydrocarbons.  Utilizing non-trival bifunctional catalysts which can catalyze methanol synthesis and methanol decomposition to hydrocarbons, synthesis gas was converted to hydrocarbons with selectivity of 100% for C sub 1 to C sub 4 at reaction temperatures of 595 to 731 exp 0 K and pressures from 27 to 68 atm. Zinc oxide and copper oxide were used to promote the methanol synthesis, and the acidic-ion exchanged form of erionite was used to catalyze the subsequent methanol decomposition to hydrocarbons. Methanol and/or dimethylether which are the precursors for hydrocarbons were found in the reactor exit. The hydrocarbons produced were between C sub 1 and C sub 4 which demonstrate the shape selectivity of erionite. The olefinic content of the hydrocarbon produced was small compared to the paraffinic content. Experiments with ethylene and hydrogen indicated that the methanol synthesis component of the hybrid catalyst was highly active toward olefin hydrogenation. Addition of water into the feed of ethylene and hydrogen caused a substantial reduction of ethylene hydrogenation. The water gas shift reaction, catalyzed by methanol synthesis component, was observed to be in dynamic equilibrium. Comparison of the different catalysts showed that erionite impregnated with zinc oxide had the highest selectivity and activity toward paraffins and olefins. (ERA citation 06:031781)