Toward hydrogen economy: Selective guaiacol hydrogenolysis under ambient hydrogen pressure
Ames Laboratory; Chemistry
Ames Laboratory, Chemistry
Applied Catalysis B: Environmental
The conversion of guaiacol into the nylon precursors, cyclohexanol and cyclohexanone, is catalyzed by palladium supported on high surface area ceria (Pd/HS CeO2) under mild conditions (100 °C, ≤1 bar H2) via sequential hydrodemethoxylation and hydrogenation. In contrast, the 2-methoxycyclohexanol side product is generated by direct guaiacol hydrogenation. Reaction selectivity is determined by competing CO bond hydrogenolysis versus arene hydrogenation. Hydrogenolysis selectivity increases as H2 pressure decreases, and over 80 % H2 is incorporated into the products at 1 bar H2. Higher reactivity of guaiacol than anisole implies that the hydroxyl group is essential in Pd/HS CeO2 catalysis. Participation of water in the conversion is evidenced by deuterium incorporation at non-exchangeable positions when the reaction is performed in D2O. The combination of near quantitative mass balance of H2, high recyclability, and use of water as a solvent offers a simple, green and efficient conversion of lignin-derived aromatics into commercial products.
DOE Contract Number(s)
Iowa State University Digital Repository, Ames IA (United States)