沉淀温度及pH值对Cu-Zn-Al-Mg甲醇合成催化剂性能的影响

Influence of precipitation temperature and pH value on performance of methanol synthesis catalyst Cu-Zn-Al-Mg

采用两步共沉淀法制备了pH值7.0、沉淀温度分别为70℃、80℃、90℃及沉淀温度为70℃,pH值8.0的合成甲醇催化剂。考察了沉淀温度及pH值对催化剂性能的影响。采用X射线衍射、N 2吸附-脱附、同步热分析及H 2-程序升温还原对催化剂样品进行表征。结果表明,当沉淀pH值为7.0时,随着沉淀温度的降低,有利于前驱体中Zn 2+取代率增加,有利于第一步形成锌铝水滑石结构的前驱体,有利于提高催化活性;略低的沉淀pH值可以提高催化剂的高温稳定性。

Methanol synthesis catalysts were prepared by two-step coprecipitation method under pH value of 7.0,precipitation temperature of 70℃,80℃,90℃and pH value of 8.0,precipitation temperature of 70℃.The effect of precipitation temperature and pH value on catalytic performance of methanol synthesis catalysts was investigated.The structure and properties of the catalysts were characterized by X-ray diffraction,N 2 adsorption-desorption,thermogravimetry and H 2-temperature-programmed reduction.The results indicated that when the precipitation pH value was 7.0,lower precipitation temperature was conductive to Zn 2+substitution in the precursor and the formation of Zn-Al hydrotalcite precursor in the first step,which were beneficial to catalytic activity.It was also found that lower precipitation pH value tended to higher temperature stability of the catalyst.