Acidity and cracking activity on MgHY zeolite

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• 作者：Miki Niwa  ; ;   ; ^{mikiniwa@chem.tottori-u.ac.jp} ; Takayuki Noda ; Katsuki Suzuki ; Nami Morishita ; Naonobu Katada
• 关键词：Lewis acidity ; Ammonia TPD ; DFT calculation ; Mg HY ; Catalytic cracking
• 刊名：Microporous and Mesoporous Materials
• 出版年：2011
• 出版时间：December 2011
• 年：2011
• 卷：146
• 期：1-3
• 页码：208-215
• 全文大小：1022 K

文摘

Solid acidity of Mg cation exchanged HY zeolite was characterized by means of IRMS¨CTPD experiments of ammonia. Enthalpy (¦¤H) of ammonia desorption on the Br?nsted acid site was kept nearly a constant 111 kJ mol^? with introducing Mg, while a strong Lewis acid site with 140?60 kJ mol^? of ¦¤H was generated. Desorption energies of NH₃ on Mg²⁺ cation located in site I?and Mg-OH⁺ in site III, which were calculated by a density functional theory, were in agreement with the measured values. Catalytic activity for octane cracking was significantly increased by the introduction of Mg, and the activity was higher on the MgHY than on the Ca- and Ba-HY at more than 40 % of the exchange degree. As a prominent character of the catalysis, hydrogen was formed in the cracking of octane on the MgHY. Discussion was made on the acidity and cracking activity of the MgHY, which was distinctively different from on Ca- and Ba-HY.