Enzymatic Biodiesel Synthesis by the Biphasic Esterification of Oleic Acid and 1-Butanol in Microreactors

Modeling the Effects of Temperature in Enzymatic Biodiesel Synthesis of Jatropha Oil: An Optimal Control Approach

Biodiesel, an alternative to diesel, is produced through the enzymatic transesterification of vegetable oil or animal fats. Enzymatic transesterification of oil is gaining more importance, as this method possesses no such disadvantages that are associated with the chemical process. Temperature is the most important factor in enzymatic transesterification for biodiesel synthesis. In this study, a mathematical model is developed to understand the effects of temperature on the enzymatic transesterification of Jatropha curcas oil. Reaction rates are expressed as a function of temperature using an appropriate function, and the effects of temperature on the overall enzymatic system are investigated using the mathematical model. A suitable temperature is determined using the mathematical model, keeping the other reaction conditions unchanged that gives maximum yield. Furthermore, an optimal control problem (OCP) is formulated to identify the temperature control strategy that maximizes the biodiesel yield while minimizing production costs. Simulated outcomes obtained from the mathematical model are analogized with the experimental results to make them acceptable. The optimal profile of temperature is determined from the developed OCP, which maximizes the biodiesel yield.

Towards biotechnological production of bio-based low molecular weight esters: a patent review

Low molecular weight (LMW) esters, like ethyl acetate, methyl formate or butyl acetate, are widespread bulk chemicals in many industries. Each of them is currently produced in huge amounts (millions of tons per year scale) starting from fossil-based feedstock and they are used mainly because of their low toxicity and complete biodegradability. Energy transition is just half of the story on the path of fighting climate change: 45% of the global greenhouse gas emissions are caused by the production and use of all the products, materials and food necessary for modern human life. If the world is to reach its climate goals, there is the need to leave underground a significant proportion of the fossil feedstock and minimize environmental impacts of chemical manufacturing. This is the reason why a lot of efforts have been made to find novel routes for LMW esters production starting from renewable raw materials (e.g. biomasses or off-gases) and exploiting low-impact manufacturing, such as microbial fermentation or enzymatic reactions. This review reports the most significant patents, in the field of white biotechnology, that will hopefully lead to the commercialization of bio-based LMW esters as well as novel strategies, current problems to be solved, newer technologies, and some patent applications aiming at possible future developments.

Kinetic Aspects of Esterification and Transesterification in Microstructured Reactors

Microstructured reactors offer fast chemical engineering transfer and precise microfluidic control, enabling the determination of reactions' kinetic parameters. This review examines recent advancements in measuring microreaction kinetics. It explores kinetic modeling, reaction mechanisms, and intrinsic kinetic equations pertaining to two types of microreaction: esterification and transesterification reactions involving acids, bases, or biocatalysts. The utilization of a micro packed-bed reactor successfully achieves a harmonious combination of the micro-dispersion state and the reaction kinetic characteristics. Additionally, this review presents micro-process simulation software and explores the advanced integration of microreactors with spectroscopic analyses for reaction monitoring and data acquisition. Furthermore, it elaborates on the control principles of the micro platform. The superiority of online measurement, automation, and the digitalization of the microreaction process for kinetic measurements is highlighted, showcasing the vast prospects of artificial intelligence applications.

5-Hydroxymethylfurfural synthesis from fructose over deep eutectic solvents in batch reactors and continuous flow microreactors

Abstract

In this work, a deep eutectic solvent (DES) composed of choline chloride (ChCl) and ethylene glycol (EG) was prepared and applied for the conversion of fructose to 5-hydroxymethylfurfural (HMF), catalyzed by HCl in both laboratory batch reactors and continuous flow microreactors. The effects of reaction temperature, batch time, catalyst loading and molar ratio of ChCl to EG on the fructose conversion and HMF yield were first investigated in the monophasic batch system of ChCl/EG DES. To inhibit HMF-involved side reactions (e.g., its polymerization to humins), methyl isobutyl ketone (MIBK) was used as the extraction agent to form a biphasic system with DES in batch reactors. As a result, the maximum HMF yield could be enhanced at an MIBK to DES volume ratio of 3:1, e.g., increased from 48% in the monophasic DES (with a molar ratio ChCl to EG at 1:3) to 63% in the biphasic system at 80°C and 5 mol% of HCl loading. Based on the optimized results in batch reactors, biphasic experiments were conducted in capillary microreactors under slug flow operation, where a maximum HMF yield of ca. 61% could be obtained in 13 min, which is similar to that in batch under otherwise the same conditions. The slight mass transfer limitation in microreactors was confirmed by performing experiments with microreactors of varying length, and comparing the characteristic mass transfer time and reaction time, indicating further room for improvement.

Highlights

• The efficient fructose conversion to HMF in deep eutectic solvents was achieved in batch reactors and microreactors.

• An HMF yield over 60% could be obtained at a fructose conversion above 90% in both reactors at 80°C within 14 min.

• The HMF yield was enhanced from 48% in the monophasic ChCl/EG system to 63% in the DES-MBIK biphasic system in batch.

• A slight mass transfer limitation was found in the biphasic slug flow microreactor.

Graphical Abstract

Two-Phase Biocatalysis in Microfluidic Droplets

This Perspective discusses the literature related to two-phase biocatalysis in microfluidic droplets. Enzymes used as catalysts in biocatalysis are generally less stable in organic media than in their native aqueous environments; however, chemical and pharmaceutical compounds are often insoluble in water. The use of aqueous/organic two-phase media provides a solution to this problem and has therefore become standard practice for multiple biotransformations. In batch, two-phase biocatalysis is limited by mass transport, a limitation that can be overcome with the use of microfluidic systems. Although, two-phase biocatalysis in laminar flow systems has been extensively studied, microfluidic droplets have been primarily used for enzyme screening. In this Perspective, we summarize the limited published work on two-phase biocatalysis in microfluidic droplets and discuss the limitations, challenges, and future perspectives of this technology.

Recent developments in microreactor technology for biocatalysis applications

Through the use of microfluidics technology, one can severely accelerate the development and optimization of biocatalytic processes. In this work, the authors present a comprehensive review of the recent advances in the field.

Sulfonic Acids Supported on UiO-66 as Heterogeneous Catalysts for the Esterification of Fatty Acids for Biodiesel Production

Zr-MOF (UiO-66) catalysts PTSA/UiO-66 and MSA/UiO-66 bearing supported sulfonic acids (p-toluenesulfonic acid and methanesulfonic acid, respectively) were prepared through a simple impregnation approach. The UiO-66-supported sulfonic acid catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The prepared heterogeneous acid catalysts had excellent stability since their crystalline structure was not changed compared with that of the original UiO-66. Zr-MOF MSA/UiO-66 and PTSA/UiO-66 were next successfully used as heterogeneous acid catalysts for the esterification of biomass-derived fatty acids (e.g., palmitic acid, oleic acid) with various alcohols (e.g., methanol, n-butanol). The results demonstrated that both of them had high activity and excellent reusability (more than nine successive cycles) in esterification reactions. Alcohols with higher polarity (e.g., methanol) affected the solid catalyst reusability slightly, while alcohols with moderate or lower polarity (e.g., n-butanol, n-decanol) had no influence. Thus, these developed sulfonic acids-supported metal-organic frameworks (UiO-66) have the potential for use in biodiesel production with excellent reusability.