Effect of polytetrafluoroethylene hollow fiber microstructure on formaldehyde carbonylation performance in membrane contactor

• Published in: Chinese journal of chemical engineering Vol. 55; no. 3; pp. 148 - 155
• Main Authors: Zhu, Zhihao, Sun, Ying, Yu, Haijun, Li, Meng, Jie, Xingming, Kang, Guodong, Cao, Yiming
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2023; Dalian National Laboratory for Clean Energy(DNL),Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences(CAS),Dalian 116023,China; School of Chemistry and Chemical Engineering,Anqing Normal University(AQNU),Anqing 246011,China%Dalian National Laboratory for Clean Energy(DNL),Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences(CAS),Dalian 116023,China
• Subjects: Carbonylation of formaldehyde; Membrane contactor; Membrane wetting; Microstructure; PTFE hollow fiber; Membrane wetting; PTFE hollow fiber; Carbonylation of formaldehyde; Membrane contactor; Microstructure
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/j.cjche.2022.05.012

[Display omitted] Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene (PTFE) membrane contactor has been proved in our previous study. In this paper, the effect of membrane microstructure on process performance was further investigated. Three porous PTFE hollow fibers with different pore sizes and one polydimethylsiloxane (PDMS)/PTFE composite membrane with dense layer were fabricated for comparison. The physical and chemical properties of four membranes, including chemical composition, morphology, contact angle, liquid entry pressure, thermodynamic analysis and gas permeability, were systemically characterized. Experiments of formaldehyde carbonylation under different reaction conditions were conducted. The results indicated that the yield of glycolic acid increased with decreasing pore size for porous membranes, which was due to the improvement of wetting behavior. The dense layer of PDMS in composite hollow fiber could effectively prevent the solvent from entering membrane pores, thus the membrane exhibited the best performance. At reaction temperature of 120 °C and operation pressure of 3.0 MPa, the yield of glycolic acid was always higher than 90% as the mass ratio of trioxane and phosphotungstic acid increased from 0.2:1 to 0.8:1. The highest turnover frequency was up to 26.37 mol⋅g−1⋅h−1. This study provided a reference for the understanding and optimization of membrane contactors for the synthesis of glycolic acid using solvent with low surface tension.