Chinese Journal of Catalysis ›› 2024, Vol. 66: 282-291.DOI: 10.1016/S1872-2067(24)60134-8

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A continuous-flow photocatalytic system for highly selective oxidation of p-xylene to terephthalic acid by decatungstate catalyst

Zheng Lia, Yuanyuan Donga, Ying Zenga, Mo Zhanga, Hongjin Lva,b,*(), Guo-Yu Yanga,*()   

  1. aMOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectric/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China
    bTangshan Research Institute, Beijing Institute of Technology, Tangshan 063000, Hebei, China
  • Received:2024-07-28 Accepted:2024-09-06 Online:2024-11-18 Published:2024-11-10
  • Contact: *E-mail: hlv@bit.edu.cn (H. Lv);ygy@bit.edu.cn (G.-Y. Yang).
  • Supported by:
    Hebei Natural Science Foundation(B2024105003);National Natural Science Foundation of China(21871025);National Natural Science Foundation of China(21831001);National Natural Science Foundation of China(22471019);Recruitment Program of Global Experts(Young Talents);BIT Excellent Young Scholars Research Fund, and the instrumental support from the Analysis and Testing Center of Beijing Institute of Technology

Abstract:

The selective oxidation of para-xylene (PX) to terephthalic acid (TPA) has received increasing attention due to the industrial applications of TPA. However, the oxidation of the C(sp3)-H bond of PX is still a main challenge because of the higher bond dissociation energy. Herein, an efficient photocatalytic system for the oxidation of PX to TPA was developed by using tetrabutylammonium decatungstate (TBADT) photocatalyst using atmospheric oxygen as oxidant and 365 nm LED light irradiation. The resulting TPA product was easily separated from the post-reaction solution through simple filtration treatment with a 93.4% yield in CH3CN (37.5% 1 mol L−1 HCl) solvent after 19-h photocatalysis. Given the easy separation of TPA and the excellent recycling stability of TBADT, a continuous-flow photoreactor was successfully designed with promising prospect for potential industrial application. Mechanistic studies elucidated that the presence of HCl additive benefits the structural integrity of [W10O32]4− anions and the transition from excited states [W10O32]4−* to wO active species, leading to enhanced photooxidation performance.

Key words: Photocatalysis, Decatungstate, Aerobic oxidation, Continuous-flow catalysis, Self-separation of product