Efficient synthesis of sugar alcohols using a composite trimetallic Pt–Ni–Sn/MWCNTs catalyst based on metal element coordination and valence regulation

Abstract

Functional sugar alcohols are a kind of burgeoning food additives to substitute saccharose due to the prominent biofunctions including moderate sweetness, low calorific values and no influence on blood sugar fluctuation, thus applied widely in food, medical, health protection as well as chemical production. Traditional synthesis of functional sugar alcohols required high temperature and H2 pressure, as well as leading to low reaction efficiency, side reactions and leaching of toxic metal ions. In the present work, Pt–Ni–Sn/MWCNTs catalyst was obtained using a liquid phase reduction method with the transition metals loading of Pt 3.4%, Ni 0.7%, Sn 0.4%, respectively. The catalyst catalyzed the preparation of xylitol, sorbitol, mannitol and galactitol with the high monosaccharide conversion (>99.5%) and yield (>99.1%) under relatively mild conditions (100 °C, 3.0 MPa H2), which were lower than ever reported. For the 13-batch reuse of Pt–Ni–Sn/MWCNTs, the total conversion of xylose was 99.4% and the total yield of xylitol was 99.2%, the productivity of 103.2 g xylitol per gram of catalyst was also obtained. Besides, no side reactions, no metal ions as well as no changes of pH were observed in the reaction process. Our trimetallic catalyst exhibited valuable potential in functional sugar alcohols production.