Facile one-pot synthesis of Cu-BTC metal-organic frameworks supported Keggin phosphomolybdic acid for esterification reactions

In the present study, phosphomolybdic acid (HPMo) supported on Cu-BTC Metal-organic frameworks (MOFs) were prepared and utilized as a solid acid catalyst. The structure of the synthesized materials was characterized by using powder XRD, FT-IR, N-2 adsorption-desorption, SEM, TEM, TG, and NH3-TPD techniques. These results exposed that HPMo was successfully encapsulated in the Cu-BTC cage and the Keggin structure of HPMo was maintained in the composite catalyst. In addition, the catalytic activity and recovery properties of the HPMo/Cu-BTC catalyst for the esterification of oleic acid with methanol into biodiesel were evaluated. These results showed that the HPMo/Cu-BTC catalyst exhibited high conversion (93.7%) and excellent reusability due to its mesoporous structure, excellent acidic activity, high BET surface area, large pore volume, and good thermal stability. Meanwhile, the kinetic studies of the esterification reaction revealed that it follows pseudo-first-order kinetics with a low activation energy of 37.5 KJ/mol. More interestingly, it shows potential application for esterification of free fatty acids (FFAs) or pretreatment of low-cost feedstocks contain high FFAs content for the green production of biodiesel.

Automated summary

In this study, HPMo supported on Cu-BTC MOFs was synthesized and used as a solid acid catalyst for the esterification of oleic acid with methanol into biodiesel. The catalyst showed high conversion and excellent reusability due to its mesoporous structure, acidic activity, surface area, and pore volume. It also exhibited potential application for esterification of FFAs or pretreatment of low-cost feedstocks for green biodiesel production.