Catalytic performance of hierarchical H-ZSM-5/MCM-41 for methanol dehydration to dimethyl ether

• 作 者: Yu Sang Hongxiao Liu Shichao He Hansheng Li Qingze Jiao Qin Wu Kening Sun
• 机 构: School of Chemical Engineering and the Environment, Beijing Institute of Technology,
• 出 处: Journal of Energy Chemistry
• 发表日期: 2013年05期
• 关键词: methanol selectivity zeolite hierarchical desorption dehydration programmed dosa

Micro-mesoporous composite molecular sieves H-ZSM-5/MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5zeolite as the source and characterized by scanning electron microscopy,transmission electron microscopy,energy dispersive spectroscopy,X-ray diffraction,N2 adsorption-desorption measurement and NH3 temperature-programmed desorption.The catalytic performances for the methanol dehydration to dimethyl ether over H-ZSM-5/MCM-41 were evaluated.Among these catalysts,H-ZSM-5/MCM-41 prepared with NaOH dosage (nNa/nSi) varying from 0.4 to 0.47 presented excellent catalytic activity with more than 80%methanol conversion and 100%dimethyl ether selectivity in a wide temperature range of 170—300℃,and H-ZSM-5/MCM-41 prepared with nNa/nSi=0.47 showed constant methanol conversion of about 88.7%,100% dimethyl ether selectivity and excellent lifetime at 220℃.The excellent catalytic performances were due to the highly active and uniform acidic sites and the hierarchical porosity in the micro-mesoporous composite molecular sieves.The catalytic mechanism of H-ZSM-5/MCM-41 for the methanol dehydration to dimethyl ether process was also discussed.

Micro-mesoporous composite molecular sieves H-ZSM-5 / MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5 zeolite as the source and characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X- ray diffraction, N2 adsorption-desorption measurement and NH3 temperature-programmed desorption. The catalytic performances for the methanol dehydration to dimethyl ether over H-ZSM-5 / MCM-41 were were.Among these catalysts, H-ZSM- 5 / MCM- 41 prepared with NaOH dosage (nNa / nSi) varying from 0.4 to 0.47 presented excellent catalytic activity with more than 80% methanol conversion and 100% dimethyl ether selectivity in a wide temperature range of 170-300 ° C, and H-ZSM-5 / MCM-41 prepared with nNa / nSi = 0.47 showed constant methanol conversion of about 88.7%, 100% dimethyl ether selectivity and excellent lifetime at 220 ° C. The excellent catalytic performances were due to the highly active and uniform acidic sites and the hierarchica l porosity in the micro-mesoporous composite molecular sieves. The catalytic mechanism of H-ZSM-5 / MCM-41 for the methanol dehydration to dimethyl ether process was also discussed.