Engineering of metal-organic framework functionalized by Fe(III) exchanged keggin unit for microwave-assisted sustainable production of biodiesel: Kinetics, thermodynamics, mechanistic insights and life-cycle cost analysis

In the present research, an attempt has been made to design a highly efficient Metal-Organic Framework encapsulated by Fe (III)-substituted keggin H3PW12O40 nanocomposite for the production of biodiesel via microwave-assisted esterification reaction within a very short duration of 40 min. This phenomenon can be attributed to the enhanced mass transfer between the surface of the catalyst and the reactants, leading to a reduction in reaction time and energy consumption. Notably, the FPW-HK catalyst significantly lowers the activation energy to 27.24 kJ/mol, achieving an outstanding biodiesel yield of 99.14 +/- 0.4 % at optimum reaction conditions, with a pseudo-first order rate constant of 0.08954 min-1. This signifies that the reaction catalyzed by the fabricated FPW-HK catalyst is highly energy efficient. Moreover, from the perspective of time and cost-effectiveness, the fabricated catalyst has the potential to reduce the overall cost of the biodiesel production, as validated by life-cycle cost analysis (LCCA). 1HNMR, 13CNMR, and GC-MS analysis were performed to quantify the composition of the produced biodiesel. Onward, the investigation of the influence of various process factors such as OA, methanol molar ratio, catalyst loading, reaction time, and temperature was performed to optimize the esterification reaction. Furthermore, a possible reaction mechanism over the surface of the synthesized FPW-HK nanocatalyst was suggested to discuss the production of biodiesel. The catalyst displayed good reusability up to six cycles besides demonstrating potential for industrial applications. The LCCA estimated the price of 1 kg of biodiesel to be merely $0.593, suitable for commercialization. Moreover, it exhibits potential for the esterification of low-cost feedstocks with high content of free fatty acids (FFA), thus displaying immense utility for industrial applications. The results suggest that the combination of MOF-supported keggin heteropolyacids and microwave irradiation can be a promising alternative to biodiesel production with reduced time and energy consumption, besides holding a significant promise for large-scale green biodiesel production for commercialization.