Synthesis of Cu/Zn/Al/Mg catalysts on methanol production by different precipitation methods

Abstract

Mg-containing Cu/Zn/Al industrial catalysts for methanol synthesis have been widely used in coal industry. The objective of this work is to investigate the influence of precipitation methods and Mg addition on the performance of Cu/Zn/Al/Mg methanol synthesis catalyst. A series of Cu0.6Zn0.3Al0.1Mgx catalysts (x: 0-0.04) were prepared by co-precipitation and fractional-precipitation methods, respectively. The catalyst samples were characterized with various methods including XRD, TG-MS, XPS, SEM, TEM/EDS, N2 physisorption and N2O chemisorption. Results show that Mg improved the BET surface area and Cu dispersion of the catalysts prepared by co-precipitation, while the corresponding catalytic activity decreased with the addition of Mg. Fractional precipitation could facilitate the Cu substitution by Zn in the subcarbonate precursor, and eliminate the negative effect caused by Mg addition. Though the formation of Mg-Al hydrotalcite was unfavorable, the catalysts obtained with fractional precipitation demonstrated better catalytic performances than those prepared by co-precipitation method. It is suggested that fractional-precipitation method is more suitable than co-precipitation for preparing the Cu/Zn/Al/Mg methanol synthesis catalyst.