Electrochemical Preparation of Cu-Mn Alloy Powder in Molten Salt for Methanol Synthesis

Abstract

Cu-Mn alloy powder was prepared by electrochemical reduction of a CuO and MnO2 mixture in a eutectic CaCl2-NaCl molten salt. The reduction pathway was probed by examining the partially reduced samples for various durations. The influence of the working temperature on the reduction was discussed. The Cu-Mn powder obtained was applied as a catalyst for methanol synthesis. The products before and after catalysis were characterized to investigate the possibility of the alloy as a catalyst for methanol synthesis. The results show that the Cu-Mn alloys, including CuMn4 and CuMn were successfully synthesized. The alloys were made up of interconnected nodular particles with a three-dimensional framework structure. The particles provided more adequate locations for catalytic reactions than the particles produced from mechanical alloying. The increased working temperature promoted the alloying process of CuMn4 and Cu to form CuMn. The electrolytic products of CuMn and CuMn4 were beneficial to synthesize methanol. The CH3OH selectivity was maintained at greater than 93%, obviously better that of the reference catalysts. MnO was formed on the top surface of the alloy particles during catalysis, separating the Cu-Mn alloys from the feed gas. This phenomenon decreased the performance of the Cu-Mn alloys for methanol synthesis.