Chinese Journal of Catalysis ›› 2019, Vol. 40 ›› Issue (4): 553-566.DOI: 10.1016/S1872-2067(19)63291-2

• Article • Previous Articles     Next Articles

Metal-organic frameworks MOF-808-X as highly efficient catalysts for direct synthesis of dimethyl carbonate from CO2 and methanol

Keng Xuana,b, Yanfeng Pua, Feng Lia, Jing Luoa,b, Ning Zhaoa, Fukui Xiaoa   

  1. a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-11-08 Revised:2018-12-26 Online:2019-04-18 Published:2019-03-14
  • Supported by:

    This work was financially supported by the Natural Science Foundation of Shanxi Province, China (201601D102006), the Science Foundation for Young Scientists of Shanxi Province, China (201701D221052), the National Natural Science Foundation of China (21776294), the Key Science and Technology Program of Shanxi Province, China (MD2014-09, MD2014-10), and the Independent Research Project of the State Key Laboratory of Coal Conversion (2018BWZ002).

Abstract:

A series of metal-organic frameworks MOF-808-X (6-connected) were synthesized by regulating the ZrOCl2·8H2O/1,3,5-benzenetricarboxylic acid (BTC) molar ratio (X) and tested for the direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH with 1,1,1-trimethoxymethane (TMM) as a dehydrating agent. The effect of the ZrOCl2·8H2O/BTC molar ratio on the physicochemical properties and catalytic performance of MOF-808-X was investigated. Results showed that a proper ZrOCl2·8H2O/BTC molar ratio during MOF-808-X synthesis was fairly important to reduce the redundant BTC or zirconium clusters trapped in the micropores of MOF-808-X. MOF-808-4, with almost no redundant BTC or zirconium clusters trapped in the micropores, exhibited the largest surface area, micropore size, and the number of acidic-basic sites, and consequently showed the best activity among all MOF-808-X, with the highest DMC yield of 21.5% under the optimal reaction conditions. Moreover, benefiting from the larger micropore size, MOF-808-4 outperformed our previously reported UiO-66-24 (12-connected), which had even more acidic-basic sites and larger surface area than MOF-808-4, mainly because the larger micropore size of MOF-808-4 provided higher accessibility for the reactant to the active sites located in the micropores. Furthermore, a possible reaction mechanism over MOF-808-4 was proposed based on the in situ FT-IR results. The effects of different reaction parameters on DMC formation and the reusability of MOF-808-X were also studied.

Key words: Metal-organic frameworks, MOF-808, Micropore size, Carbon dioxide utilization, Dimethyl carbonate