Chinese Journal of Catalysis ›› 2019, Vol. 40 ›› Issue (6): 856-866.DOI: 10.1016/S1872-2067(19)63324-3

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Cooperative structure-directing effect of choline cation and *BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolite

Wenhua Fua,b, Zhiqing Yuana, Shaoqing Jina, Wei Liua, Zhendong Wanga, Chuanming Wanga, Yangdong Wanga, Weimin Yanga, Ming-Yuan Heb   

  1. a State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, Sinopec Shanghai Research Institute of Petrochemical Technology, Shanghai 201208, China;
    b Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
  • Received:2019-01-07 Revised:2019-01-26 Online:2019-06-18 Published:2019-04-26
  • Contact: S1872-2067(19)63324-3
  • Supported by:

    This work was supported by the National Key R&D Program of China (2017YFB0702800), National Natural Science Foundation of China (21802168, 21503280, 21603277), and China Petrochemical Corporation (Sinopec Group).

Abstract:

In this contribution, we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate *BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time. *BEA zeolites, at variance with any other aluminosilicate zeolites, can serve as heterogeneous seeds for the growth of IWR zeolites and play a cooperative structure-directing role. The crystallization process was investigated using multiple techniques to characterize a series of solid products obtained with various crystallization times. The experiments clearly showed the dissolution of the *BEA zeolite and of an intermediate CDO-type structure. A plausible mechanism for the novel cooperative synthesis has been proposed. The crystallization of the IWR zeolite involves several steps, among which the crucial one is believed to be the reassembly of the building units produced from the decomposition of *BEA zeolite seeds, induced by choline molecules. Having similar structure and common building units (four-, five-, and six-membered rings) with the IWR zeolite, the *BEA zeolite is capable of promoting the reassembly of the building units and can thus play a cooperative structure-directing role. By highlighting the cooperative structure-directing effect of organic molecules and heterogeneous seeds, this study opens up new perspectives for the synthesis of target zeolites that are difficult to prepare by traditional methods. This new synthetic route is also expected to shed light on the discovery of novel zeolites.

Key words: IWR zeolite, Cooperative structure-directing effect, Organic structure-directing agent, Choline cation, Heterogeneous seeds, *BEA zeolite