Layered double hydroxides as precursors of Cu catalysts for hydrogen production by water-gas shift reaction

Various Cu catalysts were prepared by the calcination and reduction of Cu-containing layered double hydroxides (LDHs) including Cu–Al LDHs, Cu–Mg–Al LDHs, Cu–Zn–Al LDHs, and Cu–Zn–Cr LDHs. The catalysts were characterized by using ICP, N 2 physisorption, TG, SEM, XRD, H 2 -TPR, and N 2 O chemisorption, and tested for the water-gas shift (WGS) reaction at 453–623 K. The characterization results reveal the formation of LDHs on the as-synthesized precursors. Upon calcination and reduction, highly dispersed Cu nanoparticles, particularly for Cu/MgO/Al 2 O 3 , were formed. The Cu 0 surface area and Cu dispersion was found to be Cu/MgO/Al 2 O 3 > Cu/Al 2 O 3 > Cu/ZnO/Al 2 O 3 > Cu/ZnO/Cr 2 O 3 . The activity of the LDHs-derived Cu catalysts for WGS decreased in the order of Cu/MgO/Al 2 O 3 ∼ Cu/ZnO/Al 2 O 3 > Cu/ZnO/Cr 2 O 3 > Cu/Al 2 O 3 . The high activity of Cu/MgO/Al 2 O 3 was attributed to its high Cu 0 surface area and Cu dispersion, while the interaction between metallic Cu and ZnO on Cu/ZnO/Al 2 O 3 might be responsible for the WGS activity. Interestingly, the highly dispersed Cu metal particles on the Cu/MgO/Al 2 O 3 catalyst seemed stable during the WGS reaction.