Chinese Journal of Catalysis ›› 2015, Vol. 36 ›› Issue (11): 1875-1885.DOI: 10.1016/S1872-2067(15)60972-X

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One-pot synthesis of a hierarchical microporous-mesoporous phosphotungstic acid-HKUST-1 catalyst and its application in the selective oxidation of cyclopentene to glutaraldehyde

Xinli Yanga, Liming Qiaoa, Weilin Daib   

  1. a School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, Henan, China;
    b Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, China
  • Received:2015-07-15 Revised:2015-09-10 Online:2015-11-02 Published:2015-11-02
  • Supported by:

    This work was supported by the Plan of Nature Science Fundamental Research in Henan University of Technology (2013JCYJ09), the Fundamental Research Funds for the Henan Provincial Colleges and Universities (2014YWQQ13), and the National Natural Science Foundation of China (20903035, 21373054).

Abstract:

A hierarchical microporous-mesoporous metal-organic framework of HKUST-1(Cu)-encapsulated phosphotungstic acid (HPW) material, referred to as HPWs@Meso-HKUST-1, is prepared by a one-pot synthesis method using cetyltrimethylammonium bromide as the supramolecular template. The addition of HPWs to the synthesis mixture of hierarchical porous HKUST-1 results in the direct encapsulation of HPWs inside the mesopores of the HKUST-1 structure, with a homogeneous distribution over the HKUST-1 crystals, which is confirmed by XRD, FT-IR, N2 adsorption, UV-Vis DRS, and TEM. FT-IR-CO adsorption experiments indicated that additional Lewis acid sites were present in the HPWs@Meso-HKUST-1 sample. The novel heterogeneous catalyst demonstrates excellent catalytic performance for the selective oxidation of cyclopentene (CPE) to glutaraldehyde (GA) using tert-butyl hydroperoxide and acetonitrile (MeCN) as the oxidant and solvent, respectively. The high activity of the catalyst is attributed to the mesostructure of the catalyst and the nature and appropriate abundance of the HPWs—being highly dispersed with the addition of Lewis sites. After a reaction for 36 h, the 30% wt% HPWs@Meso-HKUST-1 catalyst exhibits a CPE conversion of 92.5% and a high GA yield of 73%. Furthermore, the HPWs@Meso-HKUST-1 material is sufficiently stable to prevent the leaching of HPWs, and behaves as a true heterogeneous catalyst that can be repeatedly recycled without sustaining a loss of activity and selectivity in the selective oxidation of CPE.

Key words: Metal-organic frameworks, HKUST-1, Phosphotungstic acids, Cyclopentene, Glutaraldehyde