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As stated last quarter, we discovered potassium as an impurity in the mixed metal oxides. The potassium was probably incorporated into the solid during the coprecipitation using K{sub 2}CO{sub 3}. Currently NH{sub 4}OH is being used as the precipitating base. We have discovered that the precipitation agent influences the surface composition of the mixed-metal oxides. Chemical analysis of the surface and bulk compositions showed significant differences in surface compositions of the K{sub 2}CO{sub 3} and NH{sub 4}OH precipitated catalysts. In TPR experiments we have discovered that the precipitating pH markedly affects the reducibility of the ZnMnCr oxides. This shows that the choice of base as well as the pH strongly affects the surface composition of the mixed metal catalysts. Additional studies are in progress in which we are studying how the precipitating agents affect the surface composition of the mixed metal oxide catalysts and how the different surface compositions affect their chemical properties and their interactions with the supported metal particles. Catalysts from our last design show a total selectivity to alcohols of 86%, a 3:1 ratio of methanol to isobutanol and an isobutanol productivity of 30--38 g/kg-hr. Process conversion is estimated to be 7--8%. These are encouraging results, andmore » it is hoped that manipulation of process variables such as temperature, pressure, syngas ratio and space velocity will lead to further improved performance.« less

Heterogeneous catalytic process for alcohol fuels from syngas. Fifth quarterly technical progress report, January--March 1993