Heterogeneous catalytic process for alcohol fuels from syngas. Sixteenth quarterly technical progress report, October--December, 1995
The principal objectives of this project are to discover and evaluate novel heterogeneous catalysts for conversion of syngas to oxygenates having use as fuel enhancers, to explore novel reactor and process concepts applicable in this process, and to develop the best total process for converting syngas to liquid fuels. Among our previous best catalysts was the family consisting of potassium-promoted Pd on a Zn/Cr spinel oxide prepared via controlled pH precipitation. We have now examined the effect of potassium promotion on (1) a Zn/Cr/O spinel and (2) on ZnO; these two individual components are used together to make our best support. The presence of excess zinc oxide has a beneficial effect on the performance of Zn/Cr spinel oxide catalysts (1) promoted with cesium and (2) promoted with both cesium and palladium. The presence of the excess zinc oxide results in a more active and selective catalyst to total alcohols and increased isobutanol rates, demonstrating the effectiveness of zinc oxide addition to the spinel support. Potassium addition promotes higher alcohol synthesis on a commercial Zn/Cr spinel oxide methanol synthesis catalyst. Incremental potassium levels (1, 3 and 5 wt%) result in an increase in total alcohol selectivity, while isobutanol. rates are maximized at 1 wt% potassium. The commercial catalyst promoted with potassium is slightly less active for isobutanol synthesis and less selective to total alcohols when compared with our spinel formulation promoted with potassium and containing excess ZnO. Surface science studies have shown that the surface of these catalysts is predominately ZnO and alkali. With use, the ZnO is reduced to Zn metal, and Cr migrates to the surface giving increased surface acidity. In addition tends to lower the overall acidity. Hydrogen can be observed on the catalyst surface by surface science studies. Hydrogen on the active catalyst is associated with the palladium.
- Research Organization:
- Union Carbide Corp., South Charleston, WV (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC22-91PC90046
- OSTI ID:
- 251625
- Report Number(s):
- DOE/PC/90046--T17; ON: DE96012299
- Country of Publication:
- United States
- Language:
- English
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