Copper crystallite size and methanol synthesis catalytic property of Cu-based catalysts promoted by Al, Zr and Mn

Abstract

Five Cu-based catalysts with different promoters (Al, Zr and Mn) were prepared by uniform coprecipitation and evaluated in a laboratory fixed bed reactor for methanol synthesis at 463–513 K and a pressure of 4 MPa. These catalysts were characterized by X-ray diffraction (XRD) and the data showed that they had similar crystal phase and copper crystallite sizes. The most active catalyst comprised fibrous particles with a ring structure. Zirconium, aluminum and manganese additives caused no evident change in the main active phase of the catalysts but gave rise to different copper crystallite sizes. The different Cu0 crystallite sizes resulted in different amounts of active sites, but the activation energies of methanol synthesis on these catalysts were all about 104 kJ/mol and turnover frequencies (TOFs) were about the same values, indicating the close relationship between methanol productivity and microstructure of Cu-based catalyst.