Functionalized organic–inorganic hybrid porous coordination polymer-based catalysts for biodiesel production via trans/esterification

Abstract

Considering the increasing heavy energy demands and severe environmental issues, researchers have been searching for an alternative renewable source of energy, aiming to achieve carbon neutralization. Biodiesel, which is deemed as an environment-friendly, sustainable, and renewable energy, has attracted extensive concerns worldwide with the merits of non-toxicity, biodegradability, and carbon-neutral nature. Generally, biodiesel is mainly produced via the transesterification of triglycerides and esterification of fatty acids with the assistance of highly effective catalytic material, which is determined to be a critical issue for biodiesel production. Benefiting from the superiorities of huge porosity, uniform pore size, controllable functional group, and excellent activity with stability, organic–inorganic hybrid porous coordination polymers (OIHPCPs) are considered to be promising catalysts for biodiesel production. However, limited reviews have concentrated on the specific application of OIHPCP-based catalytic materials for the production of biodiesel. With this, this study systematically reviews the current application of OIHPCPs in catalyzing the trans/esterification of liquid biomass for biodiesel production, including pristine metal–organic frameworks (MOFs), functionalized MOFs (i.e., acid, base, bifunctional, and enzymatic), MOF derivates, unconventional MOFs (UMOFs), and biomass derivate coordination polymers catalysts. Besides, the important impacts of trans/esterification parameters, such as the amount of catalyst, type and molar ratio of alcohol, reaction temperature and time, water and fatty acids content of the substrate, and auxiliary production technology of biodiesel are also comprehensively evaluated. Finally, the corresponding plausible reaction mechanisms and main conclusions together with future perspectives for OIHPCP applications in biodiesel production are further emphasized. This review is timely and conducive for advancing the bioenergy realms and achieving carbon neutrality.