Elucidating the effect of solid base on the hydrogenation of C5 and C6 sugars over Pt-Sn bimetallic catalyst at room temperature.

Conversion of sugars into sugar alcohols at room temperature with exceedingly high yields are achieved over Pt-Sn/γ-AlO catalyst in the presence of calcined hydrotalcite. pH of the reaction mixture significantly affects the conversion and selectivity for sugar alcohols. Selection of a suitable base is the key to achieve optimum yields. Various solid bases in combination with Pt-Sn/γ-AlO catalysts were evaluated for hydrogenation of sugars. Amongst all combinations, the mixture (1:1 wt/wt) of Pt-Sn/γ-AlO and calcined hydrotalcite showed the best results. Hydrotalcite helps to make the pH of reaction mixture alkaline at which sugar molecules undergo ring opening. The sugar molecule in open chain form has carbonyl group which can be polarized by Sn in Pt-Sn/γ-AlO and Pt facilitates the hydrogenation. In the current work, effect of both; solid base and Sn as a promoter has been studied to improve the yields of sugar alcohols from various C5 and C6 sugars at very mild reaction conditions.