Hydrogenolysis of glycidol as an alternative route to obtain 1,3-propanediol selectively using MOx-modified nickel-copper catalysts supported on acid mesoporous saponite

Ni and Cu mono- and bimetallic catalysts modified with various types of acid oxides MOx (M=Mo, V, W, and Re) were tested for the hydrogenolysis of glycidol as an alternative route to the hydrogenolysis of glycerol to obtain 1,3-propanediol (1,3-PrD). Characterization results revealed that the presence of modifiers affected the dispersion and reducibility of the NiO particles and the strength and amount of acid sites. Among the modifiers tested, Re led to the highest activity, a high propanediols selectivity, and the highest 1,3-PrD/1,2-propanediol (1,2-PrD) ratio. The Ni-Cu/Re ratio was optimized to improve the catalytic activity. The best catalytic result, with a 46 % 1,3-PrD yield and a 1,3-PrD/1,2-PrD ratio of 1.24, was obtained if the monometallic Ni catalyst at 40 wt % loading and modified with 7 wt % Re was used at 393 K and 5 MPa H2 pressure after 4 h of reaction. The overall 1,3-PrD yield starting from glycerol and assuming a two-step synthesis (glycerol¿glycidol¿1,3-PrD) and a yield of 78 % for the first step would be 36 %. This 1,3-PD yield is the highest for a reaction catalyzed by a non-noble metal and is comparable to the direct hydrogenolysis of glycerol using noble metal catalysts at a longer time and a high H2 pressure.Peer ReviewedPostprint (author's final draft

Renewable Chemicals: Dehydroxylation of Glycerol and Polyols

The production of renewable chemicals is gaining attention over the past few years. The natural resources from which they can be derived in a sustainable way are most abundant in sugars, cellulose and hemicellulose. These highly functionalized molecules need to be de-functionalized in order to be feedstocks for the chemical industry. A fundamentally different approach to chemistry thus becomes necessary, since the traditionally employed oil-based chemicals normally lack functionality. This new chemical toolbox needs to be designed to guarantee the demands of future generations at a reasonable price. The surplus of functionality in sugars and glycerol consists of alcohol groups. To yield suitable renewable chemicals these natural products need to be defunctionalized by means of dehydroxylation. Here we review the possible approaches and evaluate them from a fundamental chemical aspect