Decomposition of Methyl Formate over Supported Pd Catalysts

Methyl formate (MF) is used as alternative carbonylating agent in many organic transformations. The current study investigates nature of decomposition of MF over Pd catalysts on different support of varying physicochemical properties. Palladium catalysts with 1 and 5 wt% supported on Mg, and 5 wt% on gamma-Al2O3 and alpha-Al2O3 were synthesized by wetness impregnation and their catalytic activities for MF decomposition were examined. MgO supported Pd with 1 wt% showed maximum MF conversion of about 40 mol% and produced predominantly carbon monoxide (CO) and methanol (MeOH) in the molar ratio of 1:1.2 at 150 A degrees C, 1 atm. However, 5 wt% Pd/MgO catalysts showed decrease in the MF conversion to 33 mol% producing CO/MeOH in the ratio of 1:1. Catalysts with 5 wt% Pd supported on gamma-Al2O3 and alpha-Al2O3 showed lower MF conversion compared to the Pd supported on MgO. Dimethyl ether (DME) was produced as the main by-product on Pd/gamma-Al2O3 apart from CO and MeOH and it is attributed to dehydration of methanol on the acidic sites of the support. Higher MF conversion on Pd/MgO catalysts is mainly attributed to the support-metal interactions which are significant in case of Pd-MgO in addition to higher Pd dispersion with 1 wt% Pd on MgO. These results suggest that the presence of Pd over basic supports can be used to produce CO at lower temperatures; hence they may be used as a source of CO for carbonylation reactions at low pressures.