Chinese Journal of Catalysis ›› 2016, Vol. 37 ›› Issue (9): 1530-1538.DOI: 10.1016/S1872-2067(16)62484-1

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Modifying the acidity of H-MOR and its catalytic carbonylation of dimethyl ether

Meixia Wang, Shouying Huang, Jing Lü, Zaizhe Cheng, Ying Li, Shengping Wang, Xinbin Ma   

  1. Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University;Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin 300072, China
  • Received:2016-04-13 Revised:2016-05-30 Online:2016-09-21 Published:2016-09-21
  • Contact: Shouying Huang, Xinbin Ma
  • Supported by:

    This work was supported by the National Natural Science Foundation of China(21325626, 21406120) and the Postdoctoral Science Foundation of China(2014M560181, 2015T80214).

Abstract:

Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework. Tailoring the acidity, particularly the distribution and location of the Brönsted acid sites in the zeolite is effective for making it a better catalyst for these reactions. We prepared a series of H-mordenite(H-MOR) samples by varying the composition of the sol-gel, using different structure directing agents and post-treatment. NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Brönsted acid sites in the 8-membered ring and 12-membered ring channels. It was shown that controlled synthesis was a promising approach to improve the concentration of Brönsted acid sites in MOR, even with a low Al content. Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Brönsted acid sites in the 8-membered ring channels. HMI as a structure-direct agent gave an obvious enrichment of Brönsted acid sites in the 8-membered ring. Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties, especially the Brönsted acid sites in the 8-membered ring channels. There was a linear relationship between methyl acetate formation and the number of Brönsted acid sites in the 8-membered ring channels, demonstrating the successful modification of acid properties. Our results provide information for the rational design and modification of zeolites with spatial constraints.

Key words: Zeolite, H-mordenite, Modification of acidity, Hydrothermal synthesis, Structure-direct agent, Post treatment, Carbonylation of dimethyl ether