Effect of the specific surface of the support and the dispersity of the metal on the activity and selectivity of aluminum-platinum catalysts with lithium additives in the dehydrogenation of higher normal paraffins

Abstract

1. We studied the effect of the support specific surface and metal dispersity in aluminum-platinum catalysts containing 0.5% platinum and 0.5 or 1.0% lithium on dehydrogenation activity and selectivity for n-dodecane at 480°C, H2/hydrocarbon ratio of 8, 1.0 gage atm, and v=10–200 h−1. 2. Change in the alumina specific surface from 180 to 80 m2/g leads to a slight decrease in the platinum specific surface and some decrease in the catalyst activity relative to overall paraffin conversion. This does not affect the olefin formation selectivity. 3. Change in the (H/Pt) platinum dispersity from 0.72 to 0.22 is accompanied by a decrease in catalyst activity relative to paraffin conversion and the selectivity of the catalyst with 0.45 platinum dispersity is ∿4% higher than that for the catalysts with 0.72 and 0.22 dispersity. 4. The dehydrogenation activity per unit surface of platinum is virtually identical in all the catalysts studied.