A Modified Co-precipitation Method to Prepare Cu/ZnO/Al2O3 Catalyst and Its Application in Low Temperature Water-gas Shift (LT-WGS) Reaction

Abstract

A modified co-precipitation method for the production of Cu/ZnO/Al2O3 complex was studied. The modification was that part of Al was introduced by adding Al3+ into Cu2+/Zn2+ solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N2 adsorption, H2-N2O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al3+ can be doped in aurichalcite lattice, and the maximum doping amount of Al3+ was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al2O3 sample produced by the modified method, in which co-precipitated Al3+ was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area (26.1 m2/g) obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al2O3, which was decomposed from pseudo-boehmite in the calcination step.