Selective production of acetol or methyl lactate from cellulose over RuSn catalysts

Designing a catalytic system that could convert cellulose to switchable C3 alcohols or esters with controllable selectivity is highly desired to meet the rapidly changing market demand. Herein, we develop RuSn catalysts with the altering Sn loadings that can achieve acetol formation from cellulose hydrogenation at 240 °C in presence of H₂ or yield methyl lactate production from cellulose conversion in methanol and water mixture at 200 °C in presence of N₂. The increased Sn contents from 3% to 6% lead to form different surface sites from Ru₃Sn₇, Ru, and SnO_x to Ru₃Sn₇ and SnO_x. The integrated Ru₃Sn₇, Ru, and SnO_x species on 1.5%Ru-3%Sn/SiO₂ catalyze isomerization, retro-aldol condensation, and hydrogenation individual steps with coordinated reaction rates, resulting in the acetol formation with a high yield of 53.7C%. Furthermore, the optimum combination of Ru₃Sn₇ and SnO_x on 1.5%Ru-6%Sn/SiO₂ contributes to the isomerization, retro-aldol condensation, dehydration, and 1,2-hydride shift, giving rise to the preferential production of methyl lactate at a 25.1C% yield. These results illustrate the feasibility of controlling the selective conversion of cellulose to C3 acetol or methyl lactate by devising a tunable catalytic system, which guides the rational design of catalysts for the selective conversion of cellulose.