Effects of zirconium on the performance of Cu-Cr-Si-O for low-temperature methanol synthesis in liquid phase
锆助剂对低温液相合成甲醇用铜铬硅催化剂性能的影响

The low-temperature methanol synthesis from syngas was studied in a semi-continuous slurry reactor using Cu-Cr-Si-O catalysts promoted by zirconia. The catalysts were characterized by BET, TPR-H_2, TPD-H_2, TPD-CO, X-ray diffraction spectroscopy and X-ray photoelectronic spectroscopy. The results showed that zirconia plays an important role in the catalytic performance improvement. With the promotion of zirconia, the reaction activity increases by 32.5 %, the selectivity of methanol reaches a maximum of 96.2%, and the reaction stability improves obviously. Zirconia acts as an effective structural promoter. It gives an enhancement in surface area of catalysts, promots the copper dispersion on surface and brings about an enrichment of copper and chromium on surface. Meanwhile, zirconia acts as an electronic promoter and Cu+ exists steadily on surface . It could be concluded from the reaction and characterization results that the excellent performance of catalysts relates directly to the presence of Cu+ on the catalyst surface and an increase of surface area of catalysts , which is promoted by zirconia. On the catalysts surface, more complex active sites composed of Zr 4+ , Cr 3+ and Cu+ provides the micro surroundings for the valence stability, which is a key factor for the activation of H-H bond and carbon-oxygen bond.