Vapor-phase reaction of polyols over copper catalysts

Vapor-phase reaction of triols and diols was performed over copper metal catalysts. Triols, such as glycerol, and 1,2,3- and 1,2,4-butanetriols, were dehydrated to form corresponding hydroxyketones. Supported copper as well as pure copper metal was an effective catalyst for the dehydration: alumina-supported copper showed the highest catalytic activity with hydroxyacetone selectivity of >90 mol% at ambient pressure of nitrogen and 250 °C. ▪ The vapor-phase reaction of triols and diols was performed over copper metal catalysts. Triols, such as 1,2,3-propanetriol (glycerol) and 1,2,3- and 1,2,4-butanetriols, were dehydrated to afford corresponding hydroxyketones, while 1,2-propanediol was dehydrogenated to form hydroxyacetone. Supported copper as well as pure copper metal was an effective catalyst for the dehydration of glycerol to produce hydroxyacetone under inert conditions. In hydrogen flow, however, copper catalyzed the hydrogenation of hydroxyacetone as well as hydrogenolysis to produce ethylene glycol. Alumina-supported copper showed the highest catalytic activity with hydroxyacetone selectivity of >90 mol% at ambient pressure of nitrogen and 250 °C. Copper metal provides an active site for the dehydration of glycerol. We propose a reaction mechanism for the dehydration of glycerol to form hydroxyacetone.