Insights into the Pd nanocatalysts directed by morphology effect for CO and methyl nitrite coupling to dimethyl oxalate

Abstract CO coupling to dimethyl oxalate (DMO) has been considered as the most important part in industrial production of ethylene glycol (EG). Five kinds of Pd nanoparticles with various morphologies were successfully synthesized by liquid-phase reduction. The exposed crystal planes of these Pd nanoparticles were identified and quantified. The corresponding supported Pd/α-Al2O3 showed excellent catalytic activities for CO coupling reaction and the catalysts including Pd icosahedra can enhanced the selectivity of DMO to 98% and remained unchanged for 50 hours. The characterization results illustrated that the exposure of Pd (111) facets enhanced the intensities of bridged CO, which contributed to the high performance of the Pd-based catalysts. DFT calculations revealed CO adsorbed on Pd (111) facets had higher binding energies. This work systematically discussed the influence of Pd morphologies. Experimental and theoretical results confirmed that the Pd (111) facets showed better catalytic activities for CO coupling reaction.