Effects of preparation variables on the activity of alumina-supported platinum catalysts for liquid phase cinnamaldehyde hydrogenation

摘要

Alumina-supported platinum catalysts were prepared through different metal doading and reduction procedures. The platinum precursors were loaded by impregantion nd ion-exchange and then reduced by hydrogen at high temperatures and by sodium tetrahydroborate solution at a low temperature of 35 deg C. The low-temperature reduced (LR)catalysts were found to produce cinnayml alcohol in high selectivities in the liquid phase hydrogenation of cinnamaldehyde, irrespective of the method of metal loading. The high-temperature reduced (HR) catalysts prepared with ion-exchange produced hydrocinnamaldehyde and cinnamyl alcohol; the selectivity of the former was larger than that of the latter. In contrast, the HR catalysts prepared with impregnation produced large amounts of by-produces and small amounts of hydrocinnamaldehyde and cinnamyl alcohol. When these HR catalysts were additionally treated with sodium tetrahydroborate solution, they indicated product distributions similar to the LR catalysts.