Current State and Perspectives on Transesterification of Triglycerides for Biodiesel Production

Biodiesel production in India: Prospects, challenges, and sustainable directions

Biodiesel has the potential to serve as a feasible substitute for fossil fuels in many sectors, including transportation and internal combustion engines, without requiring extensive modifications. UsinHemg alternative energy sources, including biodiesel, is necessary to effectively tackle the growing demand predominantly observed in the transportation sector. This review is aimed to examine the technological progress, potential benefits, obstacles, and prospects associated with using biodiesel in India. India exhibits a significant potential for biodiesel production due to the abundance of various biofuel crops within its territory. The information supplied includes recent information from official government reports and literature. Collaborative efforts among all stakeholders in the energy industry can achieve the realization of reducing imports of petroleum-based fuel. However, it is essential to consider several significant elements specific to the Indian context when considering the utilization of biodiesel. The reported findings in this research are expected to shed light on the current and prospects of biodiesel deployment in India.

Engine Performance of High-Acid Oil-Biodiesel through Supercritical Transesterification

Relatively cheaper high-acid oil was used to make biodiesel through supercritical methanol transesterification, where high FFA contents in feedstock might conversely enhance the reaction extent. A direct-injection diesel engine and a dynamometer were used to analyze the engine characteristics of the high-acid oil-biodiesel. The experimental results show that the biodiesel made in this study had adequate fuel properties. This present biodiesel from high-acid oil was found to bear a lower heating value and equivalence ratio, with higher exhaust gas temperature, brake-specific fuel consumption (bsfc), and excess air ratio, than super-low sulfur diesel (SLSD). The biodiesel appeared to have larger-sized carbon residue left after the burning process in comparison with that of SLSD. The higher engine speed resulted in higher exhaust gas temperature and equivalence ratio, while lower bsfc, excess air ratio, was observed for the biodiesel. Supercritical methanol transesterification has been successfully proven to convert those low-cost feedstocks to renewable biodiesel products which own competitive engine performance in this study.

The Role of Surface Complexes in Ketene Formation from Fatty Acids via Pyrolysis over Silica: from Platform Molecules to Waste Biomass

Fatty acids (FA) are the main constituents of lipids and oil crop waste, considered to be a promising 2G biomass that can be converted into ketenes via catalytic pyrolysis. Ketenes are appraised as promising synthons for the pharmaceutical, polymer, and chemical industries. Progress in the thermal conversion of short- and long-chain fatty acids into ketenes requires a deep understanding of their interaction mechanisms with the nanoscale oxide catalysts. In this work, the interactions of fatty acids with silica are investigated using a wide range of experimental and computational techniques (TPD MS, DFT, FTIR, in situ IR, equilibrium adsorption, and thermogravimetry). The adsorption isotherms of linear and branched fatty acids C1-C6 on the silica surface from aqueous solution have been obtained. The relative quantities of different types of surface complexes, as well as kinetic parameters of their decomposition, were calculated. The formation of surface complexes with a coordination bond between the carbonyl oxygens and silicon atoms in the surface-active center, which becomes pentacoordinate, was confirmed by DFT calculations, in good agreement with the IR feature at ∼1680 cm 1. Interestingly, ketenes release relate to these complexes' decomposition as confirmed by the thermal evolution of the absorption band (1680 cm-1) synchronously with the TPD peak of the ketene molecular ion. The established regularities of the ketenezation are also observed for the silica-induced pyrolysis of glyceryl trimyristate and real waste, rapeseed meals.

Performance and emission characteristics of a diesel engine fuelled by biodiesel from black soldier fly larvae: Effects of synthesizing catalysts with citric acid

Biodiesel has several environmental benefits, such as biodegradability, renewability and lower soot emissions. However, biodiesel has undesirable properties such as higher viscosity and density and low calorific value compared to petroleum diesel, resulting in high Brake Specific Fuel Consumption (BSFC), reduced Brake Power (BP) and increased NOX emissions creating an environmental concerns in biodiesel development. This study investigated the effects of synthesizing transesterification catalysts (CaO and NaOH) with Citric Acid (CA) on the quality of biodiesel and biodiesel blends produced from Black Soldier Fly Larvae (BSFL) (Hermetia Illucens). The quality of biodiesel and blends was determined based on fuel properties, engine performance and emission composition characteristics. The tests were performed on a single-cylinder, four-stroke, Compression Ignition (CI) diesel engine at five loads at a constant speed of 1500 rpm. The results showed that synthesizing the catalysts with CA significantly affected the fatty acid profile of the biodiesel compared to physical fuel properties. B100 (pure BSFL biodiesel) exhibited higher BSFC by 10.57-13.97 % and lower BP by 4.21-7.83 % than diesel fuel. However, the Brake Thermal Efficiency (BTE) of biodiesel was higher than that of diesel fuel by 0.82-4.34 % at maximum load. Synthesizing catalysts with CA improved the viscosity of biodiesel by 0.93-2.81 % and effectively reduced NOX, HC and Smoke opacity by 2.23-3.16 %, 4.95-5.83 % and 20.51-41.15 %, respectively.

Enzyme immobilization technology as a tool to innovate in the production of biofuels: A special review of the Cross-Linked Enzyme Aggregates (CLEAs) strategy

This review emphasizes the crucial role of enzyme immobilization technology in advancing the production of two main biofuels, ethanol and biodiesel, with a specific focus on the Cross-linked Enzyme Aggregates (CLEAs) strategy. This method of immobilization has gained attention due to its simplicity and affordability, as it does not initially require a solid support. CLEAs synthesis protocol includes two steps: enzyme precipitation and cross-linking of aggregates using bifunctional agents. We conducted a thorough search for papers detailing the synthesis of CLEAs utilizing amylases, cellulases, and hemicellulases. These key enzymes are involved in breaking down starch or lignocellulosic materials to produce ethanol, both in first and second-generation processes. CLEAs of lipases were included as these enzymes play a crucial role in the enzymatic process of biodiesel production. However, when dealing with large or diverse substrates such as lignocellulosic materials for ethanol production and oils/fats for biodiesel production, the use of individual enzymes may not be the most efficient method. Instead, a system that utilizes a blend of enzymes may prove to be more effective. To innovate in the production of biofuels (ethanol and biodiesel), enzyme co-immobilization using different enzyme species to produce Combi-CLEAs is a promising trend.

Rhizopus stolonifer biomass catalytic transesterification capability: optimization of cultivation conditions

BACKGROUND

Using fungal biomass for biocatalysis is a potential solution for the expensive cost of the use o enzymes. Production of fungal biomass with effective activity requires optimizing the cultivation conditions.

RESULTS

Rhizopus stolonifer biomass was optimized for transesterification and hydrolysis of waste frying oil (WFO). Growth and biomass lipolytic activities of R. stolonifer improved under shaking conditions compared to static conditions, and 200 rpm was optimum. As biomass lipase and transesterification activities inducer, olive oil was superior to soybean, rapeseed, and waste frying oils. Biomass produced in culture media containing fishmeal as an N-source feedstock had higher lipolytic capabilities than corn-steep liquor and urea. Plackett Burman screening of 9 factors showed that pH (5-9), fishmeal (0.25-1.7%, w/v), and KH2PO4 (0.1-0.9%, w/v) were significant factors with the highest main effect estimates 11.46, 10.42, 14.90, respectively. These factors were selected for response surface methodology (RSM) optimization using central composite design (CCD). CCD models for growth, biomass lipase activity, and transesterification capability were significant. The optimum conditions for growth and lipid modification catalytic activities were pH 7.4, fishmeal (2.62%, w/v), and KH2PO4 (2.99%, w/v).

CONCLUSION

Optimized culture conditions improved the whole cell transesterification capability of Rhizopus stolonifer biomass in terms of fatty acid methyl ester (FAME) concentration by 67.65% to a final FAME concentration of 85.5%, w/w.

Organocatalysis with carbon nitrides

Carbon nitrides, a distinguished class of metal-free catalytic materials, have presented a good potential for chemical transformations and are expected to become prominent materials for organocatalysis. This is largely possible due to their low cost, exceptional thermal and chemical stability, non-toxicity, ease of functionalization, porosity development, etc. Especially, the carbon nitrides with increased porosity and nitrogen contents are more versatile than their bulk counterparts for catalysis. These N-rich carbon nitrides are discussed in the earlier parts of the review. Later, the review highlights the role of such carbon nitride materials for the various organic catalytic reactions including Knoevenagel condensation, oxidation, hydrogenation, esterification, transesterification, cycloaddition, and hydrolysis. The recently emerging concepts in carbon nitride-based organocatalysis have been given special attention. In each of the sections, the structure-property relationship of the materials was discussed and related to their catalysis action. Relevant comparisons with other catalytic materials are also discussed to realize their real potential value. The perspective, challenges, and future directions are also discussed. The overall objective of this review is to provide up-to-date information on new developments in carbon nitride-based organic catalysis reactions that could see them rising as prominent catalytic materials in the future.

Electrochemical Characterization of Biodiesel from Sunflower Oil Produced by Homogeneous Catalysis and Ultrasound

Biofuel production has increased significantly in several countries in recent decades. Different evaluation techniques are required for their characterization. The study measures the properties of the obtained biodiesel and a commercial diesel sample, using the techniques of open circuit potential, linear scanning voltammetry and electrochemical impedance spectroscopy. The transesterification reaction between sunflower oil and methanol was carried out with ultrasound as the energy source. The determination of triglyceride conversion to biodiesel is performed by high performance liquid chromatography (HPLC), obtaining up to 99.79% with a yield of 93.40% at a transesterification temperature of 50 ∘C for 60 min with a methanol/oil molar ratio of 6:1. The potassium hydroxide catalyst concentration was 1.0 g catalyst/100 g oil. The biodiesel samples generally showed open circuit potential (OCP) values less than 790 mV and stabilization time less than 120 s, Linear sweep voltammograms (LSV) show no reaction peaks with current densities on the order of NanoAmpere, Electrochemical impedance spectroscopy (EIS) showed a capacitive system with impedances on the order of MΩ cm2 at low frequency; This information could help characterize biofuels and other similar materials.

Editorial: Special Issue on “Catalytic Processes in Biofuel Production and Biomass Valorization”

The valorization of waste materials is a viable alternative to traditional disposal systems, including in the field of renewable energy, biofuels and biomass [...]

A Review of Biomass-Derived Heterogeneous Catalysts for Biodiesel Production

The scientific community is being forced to consider alternative renewable fuels such as biodiesel as a result of the sharp increases in the price of petroleum and the increased demand for petroleum-derived products. Transesterification is a technique used to create biodiesel where a variety of edible oils, non-edible oils, and animal fats are used. For this, either a homogeneous or heterogeneous catalyst is utilized. An appropriate catalyst is chosen based on the quantity of free fatty acid content in the oil. The main distinction between homogeneous and heterogeneous catalysts is that compared to the heterogeneous catalyst, the homogeneous catalyst is not affected by the quantity of free fatty acids in the oil. Early methods of producing biodiesel relied on homogeneous catalysts, which have drawbacks such as high flammability, toxicity, corrosion, byproducts such as soap and glycerol, and high wastewater output. The majority of these issues are solved by heterogeneous catalysts. Recent innovations use novel heterogeneous catalysts that are obtained from biomass and biowaste resources. Numerous researchers have documented the use of biomass-derived heterogeneous catalysts in the production of high-quality, pure biodiesel as a potentially greener manufacturing method. The catalysts were significantly altered through conventional physical processes that were both cost- and energy-effective. The present review is intended to analyze catalysts from biowaste for making biodiesel at a minimal cost. The most recent methods for creating diverse kinds of catalysts—including acidic, basic, bifunctional, and nanocatalysts—from various chemicals and biomass are highlighted in this review. Additionally, the effects of various catalyst preparation methods on biodiesel yield are thoroughly explored.

Niger Seed Oil-Based Biodiesel Production Using Transesterification Process: Experimental Investigation and Optimization for Higher Biodiesel Yield Using Box–Behnken Design and Artificial Intelligence Tools

The present work aims at cost-effective approaches for biodiesel conversion from niger seed (NS) oil by employing the transesterification process, Box–Behnken design (BBD), and artificial intelligence (AI) tools. The performances of biodiesel yield are reliant on transesterification variables (methanol-to-oil molar ratio M:O, reaction time Rt, catalyst concentration CC, and reaction temperature RT). BBD matrices representing the transesterification parameters were utilized for experiment reductions, analyzing factor (individual and interaction) effects, deriving empirical equations, and evaluating prediction accuracy. M:O showed a dominant effect, followed by CC, Rt, and RT, respectively. All two-factor interaction effects are significant, excluding the two interactions (Rt with RT and M:O with RT). The model showed a good correlation or regression coefficient with a value equal to 0.9869. Furthermore, the model produced the best fit, corresponding to the experimental and predicted yield of biodiesel. Three AI algorithms were applied (the big-bang big-crunch algorithm (BB-BC), firefly algorithm (FA), and grey wolf optimization (GWO)) to search for the best transesterification conditions that could maximize biodiesel yield. GWO and FA produced better fitness (biodiesel yield) values compared to BB-BC. GWO and FA experimental conditions resulted in a maximum biodiesel yield equal to 95.3 ± 0.5%. The computation time incurred in optimizing the biodiesel yield was found to be equal to 0.8 s for BB-BC, 1.66 s for GWO, and 15.06 s for FA. GWO determined that the optimized condition is recommended for better solution accuracy with a slight compromise in computation time. The physicochemical properties of the biodiesel yield were tested according to ASTM D6751-15C; the results are in good agreement and the biodiesel yield would be appropriate to use in diesel engines.

Heterogeneous Catalyzed Biodiesel Production Using Cosolvent: A Mini Review

Biodiesel is gaining recognition as a good replacement for typical diesel owing to its renewability, sustainability, and eco-friendly nature. Transesterification is the leading route for biodiesel generation, which occurs during homogeneous/heterogeneous/enzymatic catalysis. Besides this, the usage of heterogeneous catalysts is considered more advantageous over homogeneous catalysts due to the easy catalyst recovery. Consequently, numerous heterogeneous catalysts have been synthesized from multiple sources with the intention of making the manufacturing process more efficient and cost-effective. Alongside this, numerous researchers have attempted to improve the biodiesel yield using heterogeneous catalysts by introducing cosolvents, such that phase limitation between oil and alcohol can be minimized. This short review is aimed at examining the investigations performed to date on heterogeneously catalyzed biodiesel generation in the presence of different cosolvents. It encompasses the techniques for heterogeneous catalyst synthesis, reported in the literature available for heterogeneous catalyzed biodiesel generation using cosolvents and their effects. It also suggests that the application of cosolvent in heterogeneously catalyzed three-phase systems substantially reduces the mass transfer limitation between alcohol and oil phases, which leads to enhancements in biodiesel yield along with reductions in values of optimized parameters, with catalyst weight ranges from 1 to 15 wt. %, and alcohol/oil ratio ranges from 5.5 to 20. The reaction time for getting the maximum conversion ranges from 10 to 600 min in the presence of different cosolvents. Alongside this, most of the time, the biodiesel yield remained above 90% in the presence of cosolvents.

Indigenous Materials as Catalyst Supports for Renewable Diesel Production in Malaysia

High energy demand from the market due to the rapid increment of the human population worldwide has urged society to explore alternatives to replace non-renewable energy. Renewable diesel produced from biomass could be the next potential energy source for its high stability, long-term storage, and comparable performance with diesel fuels. In producing renewable diesel, the application of catalyst is essential, and the catalyst support is synthesized with the catalyst to enhance the reaction rate and catalytic properties. In this review, the type of catalyst support will be reviewed along with a brief introduction to biodiesel and renewable diesel production, especially focusing on zeolites as the catalyst support. The enhancement of catalyst support will be critically discussed to improve the catalytic performance of support in renewable diesel production and important aspects such as the stability and recyclability of the supported catalyst are included. The application of the supported catalyst in increasing the selectivity and yield of renewable diesel is significant, in which the catalytic properties depend on the interaction between catalyst and catalyst support. The supported catalyst as a favorable substance to assist in enhancing renewable diesel yield could lead to a sustainable and greener future for the biofuel industry in Malaysia.

Potential use of industrial by-products as promising feedstock for microbial lipid and lipase production and direct transesterification of wet yeast into biodiesel by lipase and acid catalysts

This work attempted the conversion of crude glycerol to lipid and lipase by Yarrowia lipolytica and the direct transesterification of wet yeast by its lipase into biodiesel via response surface methodology to enhance the cost-effectiveness of biodiesel production from the lipids. The yeast grew better and accumulated a high amount of lipids on the waste combined with fish waste hydrolysate, but only exhibited high lipase activity on the waste supplemented with surfactants (i.e., gum Arabic, Tween 20, Tween 80). However, the combination of both wastes and Tween 80 further improved growth, lipid productivity, and lipase activity. More importantly, lipase-direct transesterification under optimal conditions (wet cell concentration of 17.97 mg-DCW, methanol loading of 8.21 µL, and hexane loading of 10.26 µL) followed by acid-catalyst transesterification (0.4 M H₂SO₄), offered high FAME yields (>90%), showing the efficiency of the process when applied for the industrialization of biodiesel production from microbial lipids.

Transesterification of Ethyl-10-undecenoate Using a Cu-Deposited V2O5 Catalyst as a Model Reaction for Efficient Conversion of Plant Oils to Monomers and Fine Chemicals

Transesterification of ethyl-10-undecenoate (derived from castor oil) with 1,4-cyclohexanedimethanol over a recyclable Cu-deposited V₂O₅ catalyst afforded 1,ω-diene, the corresponding cyclohexane-1,4-diylbis(methylene) bis(undec-10-enoate), a promising monomer for the synthesis of biobased polyesters, in an efficient manner. Deposition of Cu plays an important role in proceeding the reaction with high selectivity, and both the activity and the selectivity are preserved for five recycled runs by the addition of the substrates. The present catalyst was effective for transesterification with other alcohols, especially primary alcohols, demonstrating a possibility of using this catalyst for efficient conversion of plant oil to various fine chemicals.

Microwave Assisted Biodiesel Production Using Heterogeneous Catalysts

As a promising renewable fuel, biodiesel has gained worldwide attention to replace fossil-derived mineral diesel due to the threats concerning the depletion of fossil reserves and ecological constraints. Biodiesel production via transesterification involves using homogeneous, heterogeneous and enzymatic catalysts to speed up the reaction. The usage of heterogeneous catalysts over homogeneous catalysts are considered more advantageous and cost-effective. Therefore, several heterogeneous catalysts have been developed from variable sources to make the overall production process economical. After achieving optimum performance of these catalysts and chemical processes, the research has been directed in other perspectives, such as the application of non-conventional methods such as microwave, ultrasonic, plasma heating etc, aiming to enhance the efficiency of the overall process. This mini review is targeted to focus on the research carried out up to this date on microwave-supported heterogeneously catalysed biodiesel production. It discusses the phenomenon of microwave heating, synthesis techniques for heterogeneous catalysts, microwave mediated transesterification reaction using solid catalysts, special thermal effects of microwaves and parametric optimisation under microwave heating. The review shows that using microwave technology on the heterogeneously catalysed transesterification process greatly decreases reaction times (5–60 min) while maintaining or improving catalytic activity (>90%) when compared to traditional heating.