Activity for liquid-phase hydrogenation of alpha,beta-unsaturated aldehydes of supported platinum catalysts prepared through low-temperature reduction

Alumina-supported platinum catalysts were prepared through the reduction of adsorbed metal precursors by sodium tetrahydroborate solution at room temperature and by hydrogen at high temperatures. The activity of the catalysts prepared was examined for liquid-phase hydrogenation of crotonaldehyde (CRAL) and 3-methylcrotonaldehyde (MCRAL) under mild conditions. In both cases of CRAL and MCRAL, the selectivity of the low-temperature reduced (LR) catalyst toward unsaturated alcohol (UOL) is higher than that of the high-temperature reduced (HR) catalyst. This is in accordance with the previous result on the hydrogenation of cinnamaldehyde, though the total activities of the LR and HR catalysts are comparable. The surface morphology of platinum particles of the LR catalyst seems to be different from that of the HR catalyst and this may be of significance for the enhanced UOL selectivity of the LR catalyst.