Promoter Modifications of Catalytic Activity and Selectivity. Final Report, April 1, 1982-March 31, 1984

摘要

The effect of alkali promoters on the activity and selectivity for CO hydrogenation was studied on supported nickel catalysts. Temperature-programmed desorption and reaction, and steady-state reaction were used. The support was shown to have a strong influence on the changes induced by the alkali promoter. On Ni/SiO sub 2 and Ni/TiO sub 2 , hydrogenation rates were significantly reduced, apparently due to weakened hydrogen bonding. This resulted in a significant increase in the olefin selectivity. On Ni/SiO sub 2 .Al sub 2 O sub 3 , the hydrogenation rates were increased, and a maximum was observed in the rates of methane and higher paraffin formation. Little change in the Ni/Al sub 2 O sub 3 catalysts was seen, except for a decrease in surface area. Temperature-programmed reaction and steady-state kinetics show good agreement for the series of catalysts. On Ni/Al sub 2 O sub 3 , the presence of multiple reaction sites was observed and studied in detail; a model was developed. The effect of potassium concentration on Ni/SiO sub 2 was large and the activity decreased rapidly even at the low concentrations. Preparation method and alkali salt used were shown to have small effects on the changes in activity and selectivity. The strong effect of the support was attributed to an interaction of the support with the promoter. (ERA citation 09:032784)