Pd-Cu@MIL-101 Bimetallic Catalyst Enhances the Performance for CO Esterification to Dimethyl Carbonate

CO esterification to dimethyl carbonate (DMC) offers a promising alternative synthesis route. Contrary to the conventional view that Pd(II) species serve as the active centers, Pd(0) confined in metal–organic frameworks (MOFs) catalyst was developed, which reversed product selectivity and enabled highly selective DMC formation. Extending beyond monometallic systems, we further investigated Pd–Cu@MOFs bimetallic catalysts, revealing that the Cu fraction plays a key role in modulating catalytic activity. A series of 2Pd-xCu@MIL-101 (x = 2, 4, 6) bimetallic catalysts by loading Pd-Cu nanoparticles (NPs) into MIL-101 were synthesized. Under identical reaction conditions, all 2Pd-xCu@MIL-101 catalysts outperformed the 2Pd@MIL-101 catalyst. The 2Pd–4Cu@MIL-101 catalyst exhibited the highest CO conversion activity (60%), markedly surpassing that of the monometallic 2Pd@MIL-101 catalyst (38%). The experimental results demonstrate that the introduction of Cu NPs decreases the particle size of Pd NPs and facilitates their incorporation into the mesopores of MIL-101. According to the characterization results of X-ray photoelectron spectra (XPS) and in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS), partial electron transfer may occur between Pd NPs and the Cr-oxo sites of MIL-101 as well as the incorporated Cu species, thereby facilitating CO activation and enhancing catalytic activity. This work provides valuable insights for the development of high-performance catalysts for CO esterification to DMC.

Graphical Abstract

The 2Pd–4Cu@MIL-101 catalyst delivers superior CO esterification activity. Cu incorporation reduces Pd size, confines Pd within MIL-101 pores, and enables electron transfer with Cu and Cr–oxo sites, thereby promoting CO activation and enhancing catalytic performance