三相淤浆床中合成气直接合成二甲醚双功能混合催化剂的失活研究

用双功能混合催化剂在三相淤浆床反应器中进行合成气直接合成二甲醚,考察双功能混合催化剂在三相床中的稳定性和失活现象。探讨了合成气含水蒸气对合成二甲醚以及合成甲醇的影响。分析了三相淤浆床反应器中直接合成二甲醚催化剂的失活原因,认为反应中生成的水是催化剂活性降低的原因之一。氨的程序升温脱附、X射线衍射、X光电子能谱表征结果证实甲醇合成催化剂中活性组分Cu晶粒的长大及甲醇合成催化剂中Cu元素流失导致双功能催化剂活性降低。

Deactivation of Bifunctional Mixed Catalyst for Dimethyl Ether Synthesis in Slurry Reactor

The stability of bifunctional mixed catalyst for dimethyl ether synthesis from synthesis gas in slurry reactor was investigated.The deactivation of mixed catalyst was found.Results of experiments show that water vapour affects the stability of mixed catalyst.The mixed catalysts before and after reaction were studied by NH_3-temperature programmed desorption(TPD),X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS).TPD results show that acidity of bifunctional catalyst is not changed.XRD and XPS results show the valence state of Cu is maintained after reaction,but Cu grain of catalyst after reaction is bigger than that of before reaction.Main reasons of mixed bifunctional catalyst for dimethyl ether synthesis are the grain growth of Cu and the loss of Cu,which resulted in the decrease of both active site and active surface.