Stable and Selective Dehydrocondensation of Methane Towards Benzene on Modified Mo/HMCM-22 Catalyst by the Dealumination Treatment |
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Authors: | Yuying Shu Ryuichiro Ohnishi Masaru Ichikawa |
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Affiliation: | (1) Catalysis Research Center, Hokkaido University, Kita-Ku, N-11, W-10, Sapporo, 060-0811, Japan |
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Abstract: | A modified Mo/HMCM-22 catalyst by the dealumination treatment (Mo/HMCM-22-D) exhibited remarkable performance for the catalytic dehydrocondensation of methane with a higher selectivity of benzene and a lower selectivity of coke, in comparison with the same Mo catalyst supported on parent HMCM-22 (Mo/HMCM-22). Excellent catalytic stability as well as a high benzene formation rate of 1500 nmol/(g-cat·s) was obtained on a 6%Mo/HMCM-22-D catalyst at 1023 K, 3 atm and 2700 ml/(g·h) owing to the efficient suppression of coke formation. Dealumination of the HMCM-22 zeolite was characterized by XRD, 27Al and 1H MAS NMR and NH3-TPD techniques. It was found that the dealumination treatment of HMCM-22 zeolite resulted in an effective suppression of acid sites, particularly the Brønsted acid sites (proton form in Al--O--Si) owing to the removal of tetrahedral framework aluminum, while the microporous structure and the zeolite framework remained unchanged. It was suggested that the stable and selective dehydrocondensation of methane towards benzene is based on the suppression of coke formation owing to the effective decrease of strong Brønsted acid sites by the dealumination treatment of the HMCM-22 zeolite. |
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Keywords: | methane dehydrocondensation benzene dealumination treatment HMCM-22 Mo catalyst MAS NMR NH3-TPD |
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