An improved dealumination method for adjusting acidity of HZSM-5 |
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Authors: | Lijun Jin Haoquan Hu Shengwei Zhu Bin Ma |
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Affiliation: | 1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, PR China;2. College of Chemistry and Chemical Engineering, Jinzhong University, Jinzhong, Shanxi 030619, PR China;3. University of Chinese Academy of Sciences, Beijing 100049, PR China |
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Abstract: | An improved dealumination method for adjusting the acidity of HZSM-5 was developed by utilizing the self-adsorbed water in HZSM-5. The parent and treated HZSM-5 were characterized by XRD, FT-IR, 27Al MAS NMR, N2 adsorption, XRF and NH3-TPD. The results showed that HZSM-5 can be dealuminated when treated at above 400 °C. About 80% acidic amount was removed from parent HZSM-5 with 8% adsorbed water and more Lewis acid sites were produced after treated at 500 °C. It is thought that the dealumination was mainly caused by its self-adsorbed water. The comparisons of the acidity in dealuminated HZSM-5 by traditionally steaming and improved methods indicated that the latter was more effective in decreasing the acidity and weakening acid strength, and more environmentally benign and timesaving. The method is also applicable to adjust acidity of other zeolites, such as HY, Hβ. |
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