铜基甲醇催化剂的高温烧结

The Sintering of a Cu-Based Methanol Synthesis Catalyst

对Cu/Zn/Al/Zr甲醇合成催化剂进行高温烧结后采用扫描电镜、透射电镜和X射线衍射等手段对烧结催化剂进行了表征,并对它们的活性和机理模型进行了评价和研究.结果表明,在较高烧结温度下Cu/Zn/Al/Zr甲醇催化剂中的Cu和ZnO晶粒增大,并使催化剂的形貌从串珠状转变为颗粒聚集体;烧结温度越高,晶粒越易增大,因而催化剂活性越低.可采用方程k1/k10=A×t–B描述催化剂失活过程.结果表明,随着烧结温度由400升至500oC,其幂指数B由0.076增至0.171,而失活级数由14降至7.在较低烧结温度下,催化剂微晶在其表面的迁移和聚集是烧结失活的主要因素.随着烧结温度升高,原子通过气相形式迁移的贡献有所增加.

The structure of a Cu/Zn/Al/Zr catalyst sintered at different temperatures was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction and correlated with methanol synthesis activity. The results showed that, at high sintering temperature, the particle size of Cu and ZnO increased, and the original chain-like catalyst changed into particle agglomerates, leading to a low catalyst activity. The equation k1/k10 = A×t^-B can be used to describe the deactivation process. With the increase of sintering temperature from 400 to 500 ℃, the power index B increased from 0.076 to 0.171, and the deactivation order decreased from 14 to 7. At lower sintering temperature, surface migration and coalescence of catalyst particles were the main deactivation mechanism. With increasing sintering temperature, there was a larger contribution from atomic gas phase transfer to catalyst deactivation.