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

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 Cu 0 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.