Advances in Enzyme and Ionic Liquid Immobilization for Enhanced in MOFs for Biodiesel Production

Abstract

Biodiesel is a promising candidate for sustainable and renewable energy and extensive research is being conducted worldwide to optimize its production process. The employed catalyst is an important parameter in biodiesel production. Metal–organic frameworks (MOFs), which are a set of highly porous materials comprising coordinated bonds between metals and organic ligands, have recently been proposed as catalysts. MOFs exhibit high tunability, possess high crystallinity and surface area, and their order can vary from the atomic to the microscale level. However, their catalytic sites are confined inside their porous structure, limiting their accessibility for biodiesel production. Modification of MOF structure by immobilizing enzymes or ionic liquids (ILs) could be a solution to this challenge and can lead to better performance and provide catalytic systems with higher activities. This review compiles the recent advances in catalytic transesterification for biodiesel production using enzymes or ILs. The available literature clearly indicates that MOFs are the most suitable immobilization supports, leading to higher biodiesel production without affecting the catalytic activity while increasing the catalyst stability and reusability in several cycles.

Recent developments of lipase immobilization technology and application of immobilized lipase mixtures for biodiesel production

“…92,116 They have been widely used as promising carriers for lipase immobilization in recent years owing to their unique characteristics: controllable morphology, a large surface area (up to 6000 m 2 g −1 ), giant porosity and strong affinity for enzymes. 81,117 Most importantly, MOFs are hybrid materials that act as both a host and a protective shell for proteins exposed to extreme environmental conditions. 5 The MOF-lipase nanocomposite displayed remarkable biocatalytic capabilities, as well as increased stability and reusability.…”

“…Among them, ZIF-8 and ZIF-L have received excellent attention for use in enzyme immobilization and other applications owing to their greater porosity, configurable surface properties, negligible cytotoxicity, extraordinary chemical and thermal stability, and ease of fabrication under mild conditions. 114,117 They are usually used for lipase encapsulation; in this concept, Rafiei et al 119 presented a new approach to encapsulation of CRL in ZIF-67. The designed CRL@ZIF-67 nano-biocatalyst retained an excellent enzymatic activity in six reuse cycles without a significant decline in its initial activity for producing biodiesel from the transesterification of soybean oil (SBO) with methanol in a solvent-free system.…”

“…Metal–organic frameworks are crystalline porous materials composed of a three‐dimensional network of inorganic metal ions/clusters and organic ligands 92,116 . They have been widely used as promising carriers for lipase immobilization in recent years owing to their unique characteristics: controllable morphology, a large surface area (up to 6000 m 2 g −1 ), giant porosity and strong affinity for enzymes 81,117 . Most importantly, MOFs are hybrid materials that act as both a host and a protective shell for proteins exposed to extreme environmental conditions 5 .…”

“…Zeolitic imidazolate frameworks (ZIFs), a subclass of MOFs, are a type of crystalline microporous mainly composed of metal ions, Zn 2+ or Co 2+ , and imidazole derivative products. Among them, ZIF‐8 and ZIF‐L have received excellent attention for use in enzyme immobilization and other applications owing to their greater porosity, configurable surface properties, negligible cytotoxicity, extraordinary chemical and thermal stability, and ease of fabrication under mild conditions 114,117 . They are usually used for lipase encapsulation; in this concept, Rafiei et al 119 .…”

Confining enzymes in porous organic frameworks: from synthetic strategy and characterization to healthcare applications

“…Benefiting from these merits, enzyme-POF systems have been successfully applied in various areas, such as chemical synthesis, food processing, pollutant degradation, energy harvest, and healthcare. [32][33][34][35][36][37][38] In this review, we describe the state-of-the-art strategies for the structural immobilization of enzyme using POFs as scaffolds and highlight how these porous framework-confined technologies can provide a cell-like microenvironment for biocatalysis. Subsequently, the advanced techniques for the characterization of the enzyme conformation, the effect of the confined microenvironment on the activity of enzymes, and new healthcare applications will be surveyed.…”