Construction of a Keggin heteropolyacid/Ni-MOF catalyst for esterification of fatty acids

• Published in: RSC advances 2021-10, Vol.11 (53), p.33416-33424
• Main Authors: Zhang, Qiuyun, Luo, Qizhi, Wu, Yaping, Yu, Rongfei, Cheng, Jingsong, Zhang, Yutao
• Format: Article
• Language: English
• Subjects: Ammonia; Catalysts; Catalytic converters; Chemistry; Conversion; Esterification; Fatty acids; Phosphomolybdic acid; Pore size; Reaction kinetics; X ray photoelectron spectroscopy
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d1ra06023f

This work reports the one-pot solvothermal synthesis of a Keggin heteropolyacid (phosphomolybdic acid, tungstophosphoric acid, or silicotungstic acid) immobilized on Ni-MOF composite catalysts for esterification of fatty acids, and the composites were further analyzed by XRD, FTIR, NH 3 -TPD, SEM, TEM, N 2 adsorption/desorption, and XPS. Among the contrastive syntheses ( i.e. , HPW/Ni-MOF, HSiW/Ni-MOF, and HPMo/Ni-MOF), HPMo/Ni-MOF exhibits the most active catalyst toward fatty acids esterification, and the characterization results also revealed that HPMo/Ni-MOF has a strong acidity, large specific surface area, and appropriate average pore size. More significantly, this catalyst exhibits a good catalytic performance (86.1% conversion) during esterification under the optimized reaction conditions, and the HPMo/Ni-MOF catalyst can remain stable after the tenth cycle with a conversion of 73.5%. Intriguingly, the esterification reaction kinetics was studied, and the activation energy was found to be 64.6 kJ mol −1 . The results indicated that the esterification of fatty acids using the HPMo/Ni-MOF catalyst is a chemically controlled reaction. The developed heteropolyacids immobilized on Ni-MOF catalysts have strong acidity and perform well in esterification.