Dilute Pd-in-Au alloy RCT-SiO2 catalysts for enhanced oxidative methanol coupling

Dilute alloy catalysts have the potential to enhance selectivity and activity for large-scale reactions. Highly dilute Pd-in-Au nanoparticle alloys partially embedded in porous silica (raspberry colloid templated (RCT)-SiO2) prove to be robust and selective catalysts for oxidative coupling of methanol. Palladium concentrations in the bimetallic nanoparticles as low as similar to 3.4 at.% catalyze the production of methyl formate with a selectivity of similar to 95% at conversions of similar to 55%, whereas conversions are low (<10%) for similar to 1.7 at.% Pd-in-Au nanoparticle and pure Au nanoparticle catalysts. Fractional reaction orders for both CH3OH and O-2 measured for similar to 3.4 at.% Pd-in-Au nanoparticles supported on RCT-SiO2 indicated a complex mechanism in which the sites for O-2 dissociation are not saturated. Optimal methyl formate production was found for an equimolar mixture. There is no conversion of methanol in the absence of O-2 between 360 and 450 K. All observations are consistent with a mechanism derived from model studies, requiring that clusters of Pd be available on the catalyst for O-2 dissociation. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Dilute alloy catalysts, particularly Pd-in-Au nanoparticle alloys, demonstrate enhanced selectivity and activity in oxidative coupling of methanol reactions. Low concentrations of palladium in bimetallic nanoparticles are effective in catalyzing the production of methyl formate with high selectivity of up to 95% under certain reaction conditions.