沉淀方法对铜基甲醇合成催化剂前驱体及其性能的影响

 分别采用共沉淀法 (CP)、两步沉淀法 (TP) 和分步沉淀法 (FP) 制备了 Cu/ZnO/Al₂O₃ 甲醇合成催化剂. 结果发现, FP 催化剂上甲醇收率比 CP 催化剂上高 46.3%, 比 TP 催化剂上高 9.3%. 采用 X 射线衍射、微分热重分析、红外光谱、N₂ 吸附-脱附、程序升温还原及 N₂O 滴定等方法表征了催化剂. 结果表明, FP 催化剂前驱体中 (Cu,Zn)₂CO₃(OH)₂ 和 (Zn,Cu)₅(CO₃)₂(OH)₆ 两种高活性物相较多, 而 (Cu,Zn)₆Al₂(OH)₁₆CO₃?4H₂O 物相较少, 焙烧后形成了较多的 CuO-ZnO 固溶体, 同时形成了较多的碳酸盐, 因而催化活性更高.

Influence of Precipitation Methods on Precursors and Properties of Cu-Based Catalyst for Methanol Synthesis

Cu/ZnO/Al₂O₃ catalyst samples for methanol synthesis were prepared by co-precipitation (CP), two-stage precipitation (TP), and fractional precipitation (FP) methods, respectively. The evaluation results showed that the methanol yields over the catalyst prepared by FP is the best, which is 46.3% higher than that over the catalyst prepared by CP and 9.3% higher than that over the catalyst prepared by TP. The catalyst samples and their precursors were characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, N₂ adsorption-desorption, temperature-programmed reduction, and N₂O titration. The results revealed that the precursor prepared by FP has higher amounts of (Cu,Zn)₂CO₃(OH)₂ and (Zn,Cu)₅(CO₃)₂(OH)₆ phases and a lower amount of the (Cu,Zn)₆Al₂(OH)₁₆ CO₃?4H₂O phase. Therefore, after calcination the catalyst has a higher amount of CuO-ZnO solid solution and carbonate formed at high temperature.