Methanol steam reforming on Pd/ZnO catalysts
The steam reforming of methanol on Pd/ZnO catalysts prepared by co-precipitation was studied in a stainless reactor under various conditions. The effects of Pd loading, reduction temperatures, reaction temperatures, weight hourly space velocity (WHSV) and molar ratio of water to methanol on the steam reforming of methanol to hydrogen were investigated. The results showed that when the mass fraction of metallic palladium was 15.9%, reaction temperature was 523—573 K, reduction temperature was 523—573 K, molar ratio of water to methanol was 1.0—1.2 and WHSV was 17.2 h -1, higher methanol conversion, higher CO_2 selectivity, higher hydrogen yield and lower outlet CO molar fraction were achieved. The stability tests over 15.9% Pd/ZnO and the commercial CuO/ZnO/Al_2O_3 catalyst were made at 573 K. The results showed that the methanol conversion over 15.9% Pd/ZnO remained constant for 8 h without deactivation. On the contrary, the methanol conversion over CuO/ZnO/Al_2O_3 catalyst gradually decreased with time on stream by 14.4%. So Pd/ZnO catalysts display better stability.