Plasma-assisted fluidized-bed atomic layer deposition of Pd-Cu nanoparticles on porous powder for CO2 hydrogenation

Abstract

A novel plasma-assisted fluidized-bed atomic layer deposition process to synthesize Pd-Cu bimetallic nanoparticles is reported, using palladium hexafluoroacetylacetonate, copper(I)-N, N′-di-iso-propylacetamidinate and H2 plasma. The process allows us to uniformly deposit Pd-Cu nanoparticles in porous powder, which is a mixture of γ-Al2O3 (30 wt%), amorphous aluminum silicate (50 wt%) and molecular sieve (20 wt%) (ASM). With metal loadings of 13.1 and 2.5 mg g−1 for Pd and Cu, respectively, the afforded 13.1Pd-2.5Cu catalyst shows excellent catalytic performance for the hydrogenation of CO2 in a dielectric barrier discharge reactor with no intentional heating. Under the condition of discharge input power of 24.6 W, H2-to-CO2 ratio of 4 in feed gas, and gas hourly space velocity of 7595 h−1, the conversion of CO2 can reach as high as 38.0%, with the CH4 and CH3OH product selectivities of 6.7% and 12.8%, respectively. Density functional theory calculations are further employed to understand the associated CH3OH formation mechanism.