Biodiesel Production Process Research Articles

Continuous reciprocating plate and packed bed multiphase reactors in biodiesel production: Advancements and challenges

Biodiesel, a renewable and environmentally friendly alternative to conventional fossil fuels, has gained significant attention over the last two decades. Continuous production of biodiesel offers efficiency, productivity, and scalability advantages. This paper provides a concise overview of continuous reactor systems for biodiesel production, focusing on two specific systems-the reciprocating plate reactor and the packed bed reactor-subjects of the authors' extensive research. A thorough comparison of these reactors, spanning biodiesel yield, reaction kinetics, and conversion efficiency, underscores their advantages. The reciprocating plate reactor demonstrates superior mixing characteristics, which improve mass transfer and reaction kinetics. Conversely, the packed bed reactor offers a higher catalyst-to-feedstock ratio and longer residence time, enhancing conversion efficiency. Both reactors exhibit favourable performance for continuous biodiesel production. This research can contribute to understanding continuous biodiesel production using innovative reactor designs. The comparative analysis between the reciprocating plate and packed bed reactors offers valuable insights for process optimization and reactor selection based on specific requirements such as feedstock availability, reaction kinetics, and economic considerations. These insights pave the way for the implementation of sustainable and efficient biodiesel production processes in the future.

Studies of polyol production by the yeast Yarrowia lipolytica growing on crude glycerol under stressful conditions

Crude glycerol, the principal by-product of biodiesel production process, was employed as substrate by three wild-type Yarrowia lipolytica strains (ACA-YC 5030, LMBF 20 and NRRL Y-323). Stressful conditions (low pH value = 2.0 ± 0.3, low incubation temperature T = 20 ± 1 °C, non-aseptic conditions) were employed. Interesting production of yeast biomass and polyols (viz. erythritol, mannitol and arabitol) was noted at pH = 2.0 ± 0.3 and T = 20 ± 1 °C. Strains failed to produce significant quantities of cellular lipid, while variable quantities of intra-cellular polysaccharides were produced. Fermentations under previously pasteurized media supported significant biomass and polyols production for most of the tested strains, while only one strain (NRRL Y-323), managed to produce polyols at media that were not previously thermally treated at all. The production of mannitol was favored at low initial glycerol (Glol0) concentrations, whereas higher Glol0 quantities favored the biosynthesis of erythritol. For the strain NRRL Y-323, highly aerated / agitated bioreactor trials showed different physiological profiles as compared to the respective flask experiments. Finally, in flask experiments with the strain NRRL Y-323 at high Glol0 amounts (≈140 g/L) at low medium pH (=2.0 ± 0.3), a significant production of polyols (=84.2 g/L) with the corresponding remarkable conversion yield on glycerol consumed = 62 % w/w was achieved. Practical applicationRenewable and biodegradable fuels, such as biodiesel, are safer and environmentally friendlier than the conventional petroleum diesel. Glycerol is a cost-effective substrate obtained as the main side-product from biodiesel production process and is currently being employed in the realm of Industrial Microbiology and Biotechnology to produce metabolic products with added value. Current research focuses on using glycerol as a starting substrate for biotechnological conversions aiming at producing, amongst other compounds, polyols, microbial biomass, citric acid, etc. from selected strains of the Generally Recognized Αs Safe (GRAS) yeast Yarrowia lipolytica. In the current investigation therefore, we examined the capacity of new wild-type non-extensively studied strains of this yeast to grow and assimilate this inexpensive substrate. Specifically, we have performed the acclimatization of the mentioned strains to stressful environments (i.e., low pH, low incubation temperature, non-aseptic conditions, etc.) and remarkable quantities of the added-value compounds (polyols, yeast mass, citric acid) were produced.

Production of biodiesel from Aspergillus terreus KC462061 using gold-silver nanocatalyst

ABSTRACT The current study aims to guarantee eco-friendliness, maximize production, and reduce biodiesel production costs using the new oleaginous fungus Aspergillus terreus KC462061 in the presence of gold-silver core–shell nanoparticles (Au@Ag NPs) as heterogeneous nanocatalysts in the process of biodiesel production. The response surface method (RSM) was used to optimize the production of Au@Ag NPs as heterogeneous nanocatalysts by A. terreus KC46206, supported by ANOVA, to validate the optimal conditions. Au@Ag NPs were characterized using UV-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The process of biodiesel production was optimized by RSM and validated using ANOVA. The maximum biodiesel yield was 43.28% at the optimum conditions of a methanol/oil ratio (4:1), amount of nanocatalyst (1.0 wt.%), reaction temperature (40 °C), reaction time (4.0 h), and shaking speed (600 rpm). The template of fatty acid methyl esters (FAME) in biodiesel displayed significantly higher saturated fatty acids (SFAs) than unsaturated fatty acids (USFAs). The quality of the biodiesel was evaluated, and it was discovered that it met the criteria established by the global specifications, especially in the United States and Europe.

Glycerol Electrooxidation in Flow Reactors

Transitioning away from fossil-fuel-based chemical manufacturing is critical in advancing towards a carbon-neutral society. Chemical manufacturing processes that can be driven by renewable energy and use renewable feeds or waste products from other processes are of particular interest. This talk focuses on utilization of glycerol, a byproduct of biodiesel production and other processes, as a platform chemical for electro-organic synthesis of a number of value-added intermediates.Oxidation of glycerol can result in ten or more different products. Processes are needed to synthesize specific products of interest selectively. Based on market size and value, the four most promising oxidation products of glycerol are lactic acid, glycolic acid, oxalic acid, and dihydroxyacetone. Electrochemical reduction and oxidation processes can, in principle, be directed to produce different products by tuning reactor and reaction conditions such as catalyst identity, electrolyte/analyte concentration, flow/stir rates, electrolyte composition, etc. While a significant body of work has studied glycerol electrooxidation (GEOR) in electrochemical cells with the goals of unraveling mechanisms and identifying better catalysts (higher rates/selectivities), transitioning some of the most promising GEOR approaches to larger scales has received limited attention.In our work, we pursue glycerol electrooxidation in flow reactor configurations that could be scaled to industrial levels. Flow electrolysis approaches, in addition to providing a scalable chemical manufacturing platform, enhance mass transfer and kinetics while retaining the ability to tune key operational parameters that determine rates and selectivities. In this talk, we will report on two aspects: (i) Product speciation: what parameters can be used to optimize product selectivity towards key desired products (e.g., lactic acid, glycolic acid), and (ii) Feedstock composition: how to utilize raw glycerol (so-called ‘crude’ glycerol, containing varying amounts of water, NaOH, and methanol), available as a byproduct from a wide variety of plants, as the feedstock. For the former, we employ a systematic design approach that seeks to optimize the interplay between the different parameters that determine current density (conversion rate) and Faradaic efficiency (selectivity). For the latter, we explore which of the other ingredients (methanol, NaOH, water) of crude glycerol needs to be controlled or adjusted for reproducible, desired outcomes of flow glycerol electrolysis.

Physics-informed Neural Network to predict kinetics of biodiesel production in microwave reactors

Microwaves are a process intensification (PI) method to deliver energy to reactive systems. Microwaves act directly on molecules’ dipolar moment, generating volumetric heating that allows temperature to rise rapidly, which directly impacts the overall rate of a reaction. Because reaction rates adhere to non-linear rate laws, predicting them is challenging. We use a Physics-informed Neural Network (PINN), a physics-driven model, to identify the reaction kinetics of a biodiesel production process. PINNs perform a regression on very few experimental data points and try to fit the physics at hand. We use a microwave reactor with a constant power input to perform the transesterification reaction, measure the infrared temperature and analyze the concentration of glycerides using GC-FID at different reaction times. We train the PINN to predict the reaction rates with respect to the Arrhenius equation. Results show that the PINN successfully identifies the rate constants, including their temperature dependency. Furthermore, the PINN can extrapolate its predictions to other power inputs without ever seeing the concentration data, generating a digital twin of the microwave-assisted reaction.

Response Surface Methodology in Biodiesel Production and Engine Performance Assessment

Biodiesel is a sustainable and green fuel with high potential for mitigating the adverse environmental impacts associated with conventional fossil fuels. Since the production of biodiesel is a complex process affected by many parameters which can influence the quality, cost, and environmental impact of the fuel, optimizing these factors is crucial to facilitate the commercialization of biodiesel and reduce emissions. Response Surface Methodology (RSM) is a statistical approach that is used to optimize processes and understand the relation between factors and their combined effect on the output response. RSM in biodiesel applications has been used to optimize process variables and to enhance the performance of biodiesel in engines. The goal of this review paper is to offer a brief overview of RSM, its benefits, and how it can be employed to improve the biodiesel production process and engine performance. The input process parameters, output response parameters, optimized combination of values, experimental design used, and the adequacy of the model and response for the studies were discussed. Additionally, this paper analyses the current status of literature on RSM in biodiesel applications, discusses the methodologies used by researchers, and provides useful information about the challenges and potential solutions. The main takeaways from this review include gaining an understanding of the benefits of RSM and its integration with other tools, insights into the challenges associated with biodiesel production and RSM limitations, along with potential research areas for further improvements.

Biodiesel Production Using Catalyst Na<sub>2</sub>O/Fly Ash from Waste Cooking Oil (WCO) with Transesterification Process

The consumption of fuel oil in all countries in the world is always increasing. Indonesia is one of the countries that are still dependent on fuel oil, especially for transportation and industry. Biodiesel is known as an alternative to diesel fuel that is believed to be able to overcome the problems of world energy needs. One of the raw materials that have the potential to be biodiesel is Waste Cooking Oil (WCO). This research aims to study the Na2O/Fly ash catalyst preparation process used for the transesterification reaction of WCO into biodiesel, study of purifying WCO as a raw material in biodiesel, analyze the effect of the methanol molar ratio to oil, catalyst loading and reaction time on the transesterification process in terms of the yield of the reaction, density, viscosity and an acid number of biodiesel product. The research method was begun preparation of Na2O/Fly ash catalyst and purification of WCO with despicing and neutralization methods. Afterwards, the transesterification process was running by varying %wt of the catalyst, the molar ratio of methanol to oil, and reaction time. The percentage weight of the catalyst used is 4% and 6% to the WCO weight, the molar ratio of methanol to oil is 6:1 and 8:1, and the transesterification reaction time used is 60, 80, 100 and 120 minutes. The results showed that the Free Fatty Acids (FFA) of WCO raw material was 3.102%, but after the despicing and neutralization processes were carried out, the FFA of WCO decreased to 2.538% and 0.282%, respectively. The optimal condition for the biodiesel production process was obtained when the catalyst weight is 6% with a molar ratio of methanol to oil by 8:1 which runs in 120 minutes. In these conditions, the obtained yield of reaction results are 99,09%, density 882 kg/m3, viscosity 11.15 cSt and an acid number of 0.2244 mg KOH/g. The results of XRD analysis on the catalyst Na2O/Fly ash is dominant by alumina (Al2O3), silica (SiO2), ferrous oxide (Fe2O3), calcium oxide (CaO), and natrium oxide (Na2O) compositions. Moreover, GCMS analysis on biodiesel showed that the methyl ester content formed was 98.13%. Based on parameters above, density and acid number has met the quality standards of SNI 7182: 2015.

Active sites engineered biomass-carbon as a catalyst for biodiesel production: Process optimization using RSM and life cycle assessment

Herein, we aimed at the production of porous biochar by simultaneous activation-graphitization. The active sites engineered biochar catalyst was functionalized using 4-DBS, which possessed a high surface area, and sulfur content of 1196.13 m2 g−1 and 1.9 mmol g−1, respectively. We extensively analyzed the catalyst using various techniques such as XRD, FTIR, TGA, NH3-TPD, SEM-EDS, TEM, BET, and XPS. We used this catalyst to optimize Jatropha curcas oil (JCO) transesterification, achieving a 97.1 ± 0.4% yield with the RSM-CCD method. Kinetic studies showed pseudo-first-order kinetics, and thermodynamics indicated an endothermic, nonspontaneous process.. A life cycle assessment was conducted to assess the environmental impacts of producing biodiesel from JCO, using 1 kg of biodiesel as the reference unit. The findings revealed that the total abiotic depletion of fossil resources throughout the entire biodiesel production process amounted to 52.1 MJ, the global warming potential was equivalent to 3.17 kg of CO2 emissions, the acidification potential was comparable to 0.027 kg of SO2 emissions, and the eutrophication potential was 0.016 kg of PO43−, human toxicity level 1.89 kg 1,4-DP eq and freshwater ecotoxicity to kg 1,4-DP equivalent for every 1 kg of biodiesel manufactured. The estimated cost of biodiesel produced was 1.3 USD ($) per kg, which mainly attributed to the high reusability of catalyst (82.5 ± 0.4% yield in 7th cycle), indicating high commercial applicability. Finally, the study proposes future recommendations based on identified gaps in the literature through innovative bibliometric analysis.

Coupling glycerol oxidation reaction using Ni-Co foam anodes to CO2 electroreduction in gas-phase for continuous co-valorization

Electrocatalytic reduction of CO2 is a promising alternative for storing energy and producing valuable products, such as formic acid/formate. Continuous gas-phase CO2 electroreduction has shown great potential in producing high concentrations of formic acid or formate at the cathode while allowing the oxygen evolution or the hydrogen oxidation reactions to occur at the anode. It is advantageous to use a more relevant oxidation reaction, such as glycerol which is a plentiful by-product of current biodiesel production process. This work successfully manages to couple the glycerol oxidation reaction with continuous gas-phase CO2 electroreduction to formate with the implementation of Ni-Co foam-based anodes. The MEA-electrolyzer developed can achieve significantly high formate concentrations of up to 359 g L-1 with high Faradaic efficiencies of up to 95%, while also producing dihydroxyacetone at a rate of 0.434 mmol m−2 s−1. In comparison with existing literature, this represents an excellent trade-off between relevant figures of merit and can remarkably contribute to a future implementation of this coupled electrochemical system approach at larger scales.

Experimental and Simulation Studies for Purification and Etherification of Glycerol from the Biodiesel Industry

In this study, a purification route was applied to crude glycerol and its valorization via etherification was evaluated. Crude glycerol samples were obtained through transesterification reactions of soybean oil with methanol using potassium hydroxide as catalyst. A set of separation steps (acidification, neutralization, salt precipitation, evaporation and removal of contaminants using ion-exchange resins) was performed for purification of crude glycerol. The glycerol contents of crude samples were 46% wt., and for purified samples they were above 98% wt. The etherification reactions were carried out with purified samples and different alcohols (ethanol, isopropanol and 3-methyl-1-butanol) placed into a batch reactor, using a small amount of Amberlyst 15 as a catalyst, with autogenous pressure and solvent-free conditions. The glycerol conversion, selectivity and yield to ethers were evaluated. A glycerol conversion of up to 97% wt. was obtained when using ethanol. For isopropanol, the glycerol conversion rate was 85% (97.1% of monoether and 2.8% of diether). However, the selectivity to ethers for 3-methyl-1-butanol was negligible (<3% wt.). A process simulation for the purification and etherification steps integrated with a biodiesel production process was assessed in terms of productivity and energy consumption, considering different scenarios of glycerol/alcohol molar ratios. Finally, main impacts on the overall energy consumption were evaluated for the purification processes (glycerol and ethers).

RSM modelling and optimization for performance evaluation of biodiesel production process from livistona jenkinsiana using NaOH as a catalyst

The production of biodiesel from conventional vegetable oils is limited by the high cost and competition with food supply. Therefore, there is a need to explore new and underutilized feedstocks that can provide abundant and low-cost oil for biodiesel production. Livistona jenkinsiana is a palm species that grows in tropical and subtropical regions of Asia. It produces oil-rich fruits that are usually discarded as waste. In this work, biodiesel was produced from Livistona jenkinsiana through transesterification reaction, and the parametric analysis was carried out. The process parameters such as reaction temperature, molar ratio, reaction time, and catalyst amount were studied, and yield (Y) was modelled using response surface methodology (RSM) as a modelling tool in MINITAB@17.1.0 software. A second-order RSM model for biodiesel yield was developed as a function of temperature, catalyst, and the molar ratio, which could predict the biodiesel yield. ANOVA results showed that temperature, catalyst, and molar ratio played an important role in the transesterification process. The optimization result showed that the optimal conditions were attained at a temperature of 61.78 °C, methanol to oil molar ratio 9.25:1, and catalyst concentration of 0.86 wt%. The highest biodiesel yield predicted was 94.47%. The reaction was carried out at a constant reaction speed of 500 rpm for 1.5 h of reaction time. The physicochemical properties of the produced biodiesel indicate that the biodiesel from Livistona jenkinsiana oil (LJO) is ideal for the production of biodiesel.

Environmental footprint evaluation of Jatropha biodiesel production and utilization in Ethiopia: a comprehensive well-to-wheel life cycle analysis

In Ethiopia, a Life Cycle Analysis of Jatropha-based biodiesel was conducted using the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model to assess energy consumption, efficiency, and greenhouse gas (GHG) emissions in the well-to-tank (WTT) and well-to-wheel stages. The inventory analysis involved field surveys and scenarios to evaluate energy savings, emission reductions, and air pollutants in biodiesel-diesel blends. In the WTT analysis, the energy consumption for producing 1 MJ of Jatropha-based biodiesel was found to be 0.43 MJ under rain-fed and 0.68 MJ under irrigated conditions. The net energy value was positive, and the net energy ratio was higher compared to that in other countries. The results show that GHG emissions at 19.8 g CO2 eq/MJ during the WTT stage can reduce environmental impacts by up to 45–87% depending on the type of irrigation used. When examining the global warming potential, it was found that the cultivation of Jatropha accounted for the highest share of GHG at 57.58%, followed by the biodiesel production process at 23.88%. On the other hand, vehicles employing B20 blend could replace 14.78% of fossil energy use and reduce 13.95% of GHG emissions per km, compared to pure diesel vehicle.

Techno-economic analysis and environmental impact assessment of biodiesel production from bio-oil derived from microwave-assisted pyrolysis of pine sawdust

Pyrolysis stands out as a highly promising technology for converting biomass. Upgrading the bio-oil to meet the requirements for fuelling internal combustion engines is indispensable. This study evaluates the economic viability of microwave-assisted pyrolysis (MAP) of pine sawdust, followed by bio-oil esterification for the production of biodiesel. Aspen Plus® was used to simulate a facility that processed 2000 metric tonnes of pine sawdust per day. The minimum fuel selling price (MFSP) of biodiesel was established through the use of a discounted cash flow analysis. A life cycle assessment approach was used to evaluate the environmental impact assessment of biodiesel production. Process modelling findings revealed that the pyrolysis section yielded 65.8 wt% bio-oil, 8.9 wt% biochar, and 25.3 wt% NCGs. The biodiesel product yield was 48 wt% of the raw bio-oil, yielding 631.7 tonnes per day of biodiesel. With the cost of methanol playing a significant role, the overall capital investment was $286.1 MM and the total yearly operating expenses were $164.9 MM. The predicted MFSP for biodiesel is $2.31/L, with yearly operational expenses and biodiesel output being the most important factors. The emission from the biodiesel production process resulted in a global warming potential of 70.97 kg CO2eq. With an anticipated MFSP that is competitive with traditional diesel fuel, the study concludes that the method is economically viable. The results underline how crucial it is to optimize crucial process variables in order to increase the process's economic viability.

Biodiesel production from microalgal biomass by Lewis acidic deep eutectic solvent catalysed direct transesterification

Traditional two steps biodiesel production process generally involves corrosive sulfuric acid in the transesterification step, which is not environmentally benign. In this work, a novel procedure was presented for the direct production of biodiesel using Lewis acid deep eutectic solvent (LADES) to avoid using sulfuric acid. Synergy between the Lewis site of the LADES catalyst and the Brønsted site from biomass pretreated by Brønsted acidic deep eutectic (BADES) has resulted in the development of a bifunctional medium considered to be appropriate for high biodiesel formation and increase the FAMEs weight. The mechanism of biodiesel formation was anticipated through the experimental and computational studies of Lewis and/or Brönsted acid sites in the reaction process. The potential interference factors of the extraction process such as time of reaction, temperature, LADES catalyst concentration in methanol, and solvent volume were further optimized experimentally, followed by the Box–Behnken method. The highest amount (39.86 mg/g) of fatty acid methyl esters (FAMEs) was obtained from Chlorella pyrenoidosa biomass at 120 °C for 90 min, 5 mL solvent volume, and 5% concentration of LADES (ChCl-CrCl3.6 H2O) catalyst in methanol. The predominant FAMEs were C16:0 (9.47 mg/g), C18:2 (12.42 mg/g), and C18:3 (8.68 mg/g), and obtained biodiesel qualities meet international standards. The recyclability of LADES was tested, and satisfactory results of FAME weight were observed up to three cycles, and the FTIR peaks of LADES catalyst after four cycles of reusing have shown the structure of DES remain stable. Despite the existence of sustainable, efficient, and less toxic ways for microalgae transesterification, further investigation is required to assess the scalability of these methods for large-scale use.

Using calcined waste fish bones as a green solid catalyst for biodiesel production from date seed oil

Abstract Since biodiesels are widely considered more environmentally friendly and ecologically sustainable than fuels derived from petroleum – as well as producing greener energy at a lower price – this belief has encouraged the growth of the bio-economy. The primary objective of this work was to investigate the use of a novel non-edible feedstock obtained from date seed oil for the production of environmentally friendly biodiesel. This was achieved via the application of creative and different hydroxyapatite (HAPT) heterogeneous catalysts. These catalysts were obtained from discarded fish bones that were synthesized from dried fish bone and subjected to calcination at different temperatures. This study used several analytical methods, including transmission electron microscopy, Brunauer–Emmett–Teller analysis, X-ray diffraction (XRD), and thermogravimetric analysis, to investigate the properties of a cost-effective and environmentally sustainable catalyst derived from waste fish bones. HAPT is the key component of calcined catalysts, and this was confirmed using XRD analysis. The findings revealed that the transesterification activity was optimal when the catalyst was calcined at 900°C. Moreover, this produced a maximum yield of 89% fatty acid ethyl esters (FAMEs) when optimal reaction conditions were achieved (3-h reaction time, 9:1 ethanol/oil molar ratio, and catalyst amount of 4.5 wt%). Additionally, the catalyst was found to be durable and reusable throughout the biodiesel production process. The confirmation of FAME production was achieved using gas chromatography–mass spectrometry. This approach could facilitate the production of low-cost, environmentally friendly technology. Additionally, it was established that the characteristics of the biodiesel complied with ASTM D6571, an American fuel regulation. Green energy approaches can also be beneficial for the environment, which could ultimately improve societal and economic development for the biodiesel business on a larger scale.

Evaluation of a hollow fiber membrane contactor reactor for reactive extraction in biodiesel production

A polypropylene hollow fiber membrane contactor reactor (HF-MCR) was used to evaluate the performance of a reactive extraction process for biodiesel production. The process involved the transesterification of soybean oil with methanol, catalyzed by sodium hydroxide. The experimental methodology assessed the impact of oil flow rate and methanol/oil molar ratio on the biodiesel (FAME) production rate, triglyceride reaction rate, and glycerin concentration in the final biodiesel product. The results demonstrated that, by employing a countercurrent configuration, is possible to extract the glycerin from the biodiesel-rich phase with methanol, achieving both the reaction and the separation stages in the same equipment. The best results were obtained at a methanol/oil molar ratio of 4:1 and an oil flow rate of 0.4 L h−1, leading to a triglyceride conversion rate of 0.14 mol h−1 and a FAME production rate of 0.24 mol h−1, equivalent to 34 % conversion and 56 % yield, respectively. The final biodiesel product showed a low concentration of glycerin, measuring only 0.06 % wt. This investigation highlights the potential of employing membrane contactors technology for the biodiesel production process, reducing the processing time by eliminating the biodiesel/glycerol separation stage, and therefore bringing down the load of downstream purification operations.

Novel Corncob‐Based Catalytic Biodiesel Production Process: Experiments, Modeling, and Simulation

AbstractA functionalized catalyst for catalyzed biodiesel production via a heterogeneous route is a highly focused area to lower the cost of production and mitigate the drawbacks of homogeneously catalyzed reactions. Production aspects such as parameter study, kinetics modeling, and simulation of continuous process flowsheets incorporating kinetic parameters are scarce in the literature. In the current work, a sulfonic group‐functionalized porous carbonaceous catalyst based on corncob was used for the esterification of oleic acid. The Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) kinetic model was found to best fit to correlate the experimental data and thus applied to deduce the kinetic parameters. The obtained kinetic parameters were incorporated into the Aspen Plus simulator to simulate the continuous biodiesel production process. The catalyst showed a strong affinity for oleic acid which enhances the reaction rate.

Transformations of Glycerol into High-Value-Added Chemical Products: Ketalization and Esterification Reactions

Biomass allows us to obtain energy and high-value-added compounds through the use of different physical and chemical processes. The glycerol obtained as a by-product in the synthesis of biodiesel is considered a biomass compound that has the potential to be used as a raw material to obtain different chemical products for industry. The development and growth of the biodiesel industry allows for the projection of glycerol biorefineries around these plants that efficiently and sustainably integrate the biodiesel production process together with the glycerol transformation processes. This work presents a review of the ketalization and esterification of glycerol to obtain solketal and acetylglycerols, which are considered products of high added value for the chemical and fuel industry. First, the general aspects and mechanisms of both reactions are presented, as well as the related chemical equilibrium concepts. Subsequently, the catalysts employed are described, classifying them according to their catalytic nature (zeolites, carbons, exchange resins, etc.). The reaction conditions used are also described, and the best results for each catalytic system are presented. In addition, stability studies and the main deactivation mechanisms are discussed. Finally, the work presents the kinetic models that have been formulated to date for some of these systems. It is expected that this review work will serve as a tool for the advancement of studies on the ketalization and esterification reactions that allow for the projection of biorefineries based on glycerol as a raw material.

Production of Biofuels from Glycerol from the Biodiesel Production Process—A Brief Review

Biodiesel is seen as a successor to diesel of petrochemical origin, as it can be used in cycle and stationary engines and be obtained from renewable raw materials. Currently, the biodiesel production process on an industrial scale is mostly carried out through the transesterification reaction, also forming glycerol as a product. Pure glycerol is used in the pharmaceutical, cosmetic, cleaning, food, and other industries. Even presenting numerous applications, studies indicate that there is a saturation of glycerol in the market, which is directly related to the production of biodiesel. This increase causes a commercial devaluation of pure glycerol, making separation and purification processes unfeasible from an economic point of view. Despite the economic unfeasibility of the aforementioned processes, they continue to be carried out due to environmental issues. Faced with the problem presented, this work provides a bibliographical review of works that aimed to use glycerol as a raw material for the production of biofuels, with these processes being carried out mostly via fermentation.

Advancing biodiesel production from Pyrus glabra seed oil: Kinetic study and RSM optimization via microwave-assisted transesterification with biocompatible hydroxyapatite catalyst

In this study, a biocompatible hydroxyapatite (HAp) catalyst was synthesized using the chemical precipitation method to create biodiesel (FAME). The HAp was characterized for its structure (FT-IR and XRD), particle size, morphology (SEM and TEM), and surface area (BET). The obtained results indicated that HAp had a spherical shape ranging in size from 28.36 to 51.40 nm, a specific surface area of 21.90 m2/g, and a pore diameter of 15.36 nm. The aforementioned catalyst was employed in the transesterification of Pyrus glabra seed oil, with the assistance of microwaves, and the optimization of the biodiesel production process was achieved using RSM-CCD. The impact of the reaction parameters, including catalyst weight (0.5–1.5 wt%), temperature (60–80 °C), and time (10–30 min), was analyzed. The highest biodiesel yield of 89.21% was achieved in 30 min using a 0.5 wt% catalyst at 80 °C. Microwave-produced FAME was evaluated with FT-IR and GC-MS analysis. GC-MS results revealed 78.02% unsaturated and 13.16% saturated FAME content. The FTIR spectrum validated the presence of methyl and ester groups in the produced biodiesel. Both the FTIR and GC-MS results illustrated that the produced biodiesel had good quality. Transesterification of Pyrus glabra seed Oil followed first-order kinetics with an activation energy of 23.20 kJ/mol and an Arrhenius constant of 2.43 × 104 min−1. The catalyst remained active over six recycling cycles without notable decline. The optimal properties of Pyrus glabra biodiesel, meeting ASTM standards, highlight its potential as a catalyst for large-scale production, aligning with the Sustainable Development Goals (SDGs).