乙二醇为原料制备乙二醇乙醚用催化剂及其失活

Catalyst Deactivation for Synthesis of Glycol Ether from Ethylene Glycol

摘要:

以硫酸铵浸渍改性的HZSM-5为催化剂催化乙二醇和乙醇合成乙二醇乙醚和乙二醇二乙醚时催化剂效率很高，乙二醇转化率能达到69.1%，乙二醇乙醚选择性达到72.9%，乙二醇二乙醚的选择性为25.3%。但催化剂在重复使用时催化活性降低较快，因此分别采用X射线衍射仪（XRD），NH3-TPD，扫描电子显微镜（SEM），电子能谱（EDS），比表面积及孔径测定仪和热重/差热分析仪（TG）对催化剂改性及使用前后晶型结构，表面酸强和酸量，表面吸附物，催化剂形貌，表面元素变化，比表面积，孔径大小等对催化剂失活原因及再生条件进行研究。结果表明，在使用后未对催化剂处理情况下，催化剂失活主要是由于表面积碳导致催化剂孔道堵塞造成的。经多次使用后催化剂缓慢失活主要是由于催化剂表面负载的S流失造成的，在整个过程中催化剂晶型结构未发生变化。

Abstract:

The catalyst was prepared with HZSM-5 as support and ammonium sulfate as modifying agent by impregnation, filtration, desiccation and calcinations. The ethylene glycol monoethyl ether and ethylene glycol diethyl ether were synthesized from ethylene glycol and ethanol by using prepared catalysts. The results showed that modified H-ZSM-5 was the better catalyst. The conversation of ethylene glycol was 69.1% and the selectivity of ethylene glycol monoethyl ether was 72.9% and selectivity of ethylene glycol diethyl ether was 25.3%. However, the catalytic performance dropped after be used. And so the catalyst samples were characterized by X-ray diffraction (XRD), temperature-programmed desorption of NH3 (NH3-TPD), scanning electron microscopy (SEM) with the energy dispersive spectroscopy (EDS), Brunner-Emmit-Teller (BET) and thermogravimetry (TG) to investigate the deactivation of the catalyst. The results showed that the catalyst deactivation did not result from the change of the crystal structure. The main reason for catalyst deactivation is the reduced of sulfur and strong acid sites because of the absorption of organic molecules on the surface or in the pore of the catalyst.