Experimental and in situ DRIFTs studies on confined metallic copper stabilized Pd species for enhanced CO2 reduction to formate

Understanding the basic principle of Pd-based bimetallic catalysts design is essential in CO2 hydrogenation to formate. In this work, Cu partially replaced the bivalence position in MgAl hydrotalcite structure was developed for achieving the highly confined Cu species, whose interaction with Pd species was systematically studied and compared with the traditional co-impregnation or stepwise impregnation method. The stable and maximum formate formation rate of 12.8 mmol/h/gmetal was obtained on Pd0.4 @CuMgAlOx catalyst under 100 °C, 4.0 MPa, H2/CO2 ratio of 3, being about double of the sum of formate production rate over the monometallic Cu and Pd catalysts. Strong synergetic interaction between Pd and the confined Cu species was observed with Cu/Pd atomic ratios of 14–181. Extensive characterization using TEM, XPS, XANES, coupled with kinetic study and in situ DRIFTs analysis revealed that the superior performance of Pd0.4 @CuMgAlOx was attributed to the confined PdCu nanoparticles with electron-rich PdCu surface.