Dictating selectivity in the catalytic vapor-phase conversion of glycerol

A viable route for the vapor-phase conversion of glycerol into value-added chemicals is herein presented. This procedure allows to dictate selectivity towards hydroxyacetone (acetol) or methylglyoxal (pyruvaldehyde) by simply tuning the experimental conditions while retaining the same catalytic system. A series of gold- and copper-based catalysts supported on gamma-alumina, including bimetallic formulations, were prepared by incipient wetness impregnation method and tested in a continuous-flow fixed-bed vertical glass reactor at ambient pressure and T = 250- 300°C. The best performance was achieved with 1%wt Au/Al2O3. Accordingly, the selectivity could be directed to acetol (sel. 72%) at 87% conversion when performing the reaction at 300°C and adding H2 to the carrier N2, or towards pyruvaldehyde (sel. 79%) at 92% conversion when adding O2 to N2 at 250°C. These relatively mild conditions not only allow for energy savings with respect to the common procedures so far reported, but also for catalyst stability that can be easily regenerated after use. Furthermore, the low metal loading in the catalyst (1% wt) and its small amount requested for each test (0.1 g catalyst) make this procedure economically sustainable.