Biofuel Synthesis Research Articles

Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization

Driven by the urgent need for sustainable alternatives to fossil fuels, the focus on the exploration of lignocellulosic biomass, particularly lignin, as a promising renewable feedstock for biofuels and high-value chemicals has intensified. This study investigated the depolymerization of KL using a DES comprising ChCl and ZnCl2. Our analysis systematically focused on the effects of reaction temperature, time, and the DES-to-lignin ratio on the yields and characteristics of the products. Optimal KL depolymerization was observed at a temperature of 190 °C and a duration of 8 h, yielding a maximum liquid product yield of 54.44% and RL yield of 45.56%. The results revealed that increasing the reaction temperature enhanced the depolymerization process owing to a reduction in the viscosity of the DES, which improved mass transfer and interactions with lignin. Under these optimal conditions, the molecular weight of the bio-oil was considerably lower (Mw = 1498 g/mol and Mn = 1061 g/mol) than that of the bio-oil obtained without DES treatment (Mw = 1872 g/mol and Mn = 1259 g/mol), indicating a more favorable molecular weight distribution with DES treatment. Furthermore, elemental analysis revealed a reduction in the O, N, and S contents of the RL following DES treatment, increasing the high heating value from 24.82 MJ kg−1 for the non-DES-treated RL to 26.44 MJ kg−1 for the DES-treated RL. These findings underscore the potential of the (ChCl:ZnCl2) DES as a sustainable and effective medium for lignin valorization, paving the way for the synthesis of high-quality biofuels and chemicals from lignocellulosic biomass.

Exploring the Impact of Environmental Conditions and Bioreactors on Microalgae Growth and Applications

Microalgae and their bioproducts have diverse applications, including wastewater remediation, CO2 fixation, and the synthesis of nutraceuticals, pharmaceuticals, and biofuels. However, the production of these organisms heavily relies upon environmental conditions, which can significantly impact growth. Furthermore, microalgae cultivation itself can be a source of economic and environmental concerns. Thus, microalgae growth systems have become a critical consideration for both research and industry, to bolster microalgae cultivation and address its accompanying issues. Both open and closed systems, such as raceway ponds and photobioreactors, respectively, are commonly used during the growth process but have their own advantages and drawbacks. However, for microalgae growth, photobioreactors may address most concerns as the system’s design lowers the risk of contamination and provides the ability to control the delivery of desired growth factors. To determine the appropriate system for targeted microalgae cultivation, it is crucial to determine factors such as the scale of cultivation and growth and productivity targets. Additionally, efficient usage of these growth systems and carefully selected incubation factors can aid in addressing some of the economic and environmental issues associated with microalgae production. This review will summarize the current applications of bioreactors in both research and industrial capacities and summarize growth and incubation factors for microalgae.

Steam Reforming of Tar Impurities from Biomass Gasification with Ni-Co/Mg(Al)O Catalysts—Operating Parameter Effects

The elimination of tar impurities from biomass gasification by catalytic steam reforming can provide clean syngas for downstream biofuel synthesis (Fischer–Tropsch). The effects of key operating parameters in CH4/tar steam reforming were investigated. Ni-Co/Mg(Al)O catalyst performance was tested at model conditions (10/35/25/25/5 wt% CH4/H2/CO/CO2/N2), changing the temperature (650–800 °C), steam-to-carbon ratio (2–5), tar loading (10–30 g/Nm3), and tar composition (toluene, 1-methylenaphthalene, and phenol). Complete tar elimination was achieved under all conditions, at the expense of catalyst deactivation by coke formation. Post-operation coke characterization was obtained with TPO-MS, Raman spectroscopy, and STEM analysis, providing vital insight into coke morphology and location. Critical low-temperature and high-tar loading limits were identified, where rapid deactivation was accompanied by increasing amounts of hard coke species. A coke classification scheme is proposed, including strongly adsorbed surface carbon species (soft coke A), initial scattered carbon filaments (hard coke B1.1), filament clusters and fused filaments (B2), and strongly deactivating bulk encapsulating coke (B3), formed through progressive filament cluster graphitization. High-molecular-weight tar was found to enhance the formation of strongly deactivating metal-particle-encapsulating coke (B1.2). The results contribute to the understanding of coke formation in the presence of biomass gasification tar impurities.

Biofuel processing in a closed-loop geothermal system

Closed-loop geothermal systems (CLGS) provide a renewable heat source for district heating and electricity production. However, high capital costs can be a barrier to these applications. This study finds that the high pressures (>8MPa) and temperatures (>240°C) attained by working fluid inside the loop present additional opportunities: driving supercritical reactions that produce biodiesel from fatty acids. A new design for a subsurface geothermal reactor is proposed, enabling biofuel processing underground without the need for conventional processing equipment (pump, heater, reactors, and heat exchangers) or fossil fuel as energy source. To analyze the feasibility of this approach and its environmental and economic effects, a computational model that incorporates the simultaneous effects of flow dynamics, heat transfer, and reaction kinetics is developed. The application of CLGS is concluded to reduce the CO2 intensity of the resulting biodiesel by up to 33%. A geothermal-driven biofuel reactor could yield up to 95% fatty acid methyl esters. Additional sensible heat carried by the products can be redirected to electricity generation or district heating. The relevant requirements and optimal operating conditions for this approach to biofuel synthesis are identified. A technoeconomic analysis shows CLGS-based biofuel production cost can be comparable to natural gas-based production (∼840 $/ton). It also indicates return-on-investment after five years and highlights the most suitable locations that combine proximity to appropriate feedstocks and subsurface conditions. Integrated biodiesel production and energy extraction provides an alternative route to harnessing geothermal energy.

Zirconium Phosphate-Pillared Zeolite MCM-36 for Green Production of γ-Valerolactone from Levulinic Acid via Catalytic Transfer Hydrogenation.

γ-valerolactone (GVL), derived from biomass, is a crucial platform compound for biofuel synthesis and various industrial applications. Current methods for synthesizing GVL involve expensive catalysts and high-pressure hydrogen, prompting the search for greener alternatives. This study focuses on a novel zirconium phosphate (ZrP)-pillared zeolite MCM-36 derivative catalyst for converting levulinic acid (LA) to GVL using alcohol as a hydrogen source. The incorporation of ZrP significantly contributes to mesoporosity and greatly enhances the acidity of the catalysts. Additionally, we employed 31P MAS NMR to comprehensively investigate the influence of phosphorus species on both the acidity and the catalytic conversion of LA to GVL. By adjusting the Zr-to-P ratios, we synthesized catalysts with enhanced acidity, achieving high conversion of LA and selectivity for GVL. The catalyst exhibited high recyclability, showing only minor deactivation over the course of five cycles. Furthermore, the catalyst was successfully applied to the one-pot conversion of furfural to GVL, showcasing its versatility in biomass conversion. This study highlights the potential of the MCM-ZrP1 catalyst for sustainable biomass conversion and offers insights for future research in renewable energy technologies.

Chemical approaches for the biomass valorisation: a comprehensive review of pretreatment strategies.

The most abundant natural renewable resource in the world, lignocellulosic biomass (LCB), has the potential to be exploited as a substitute green feedstock for the synthesis of various chemicals, materials, and biofuels. The annual global production of 13 billion tonnes of LCB offers an opportunity to cater to the increasing energy and materials requirement of process industries and also restricts the discharge of greenhouse gases. Although LCB is enriched with valuable ingredients such as cellulose, lignin, and hemicellulose, its recalcitrant nature limits its efficient utilisation. These components of LCB are strongly interlinked with each other, which resists their isolation and conversion valorisation into useful products. To disrupt the complicated structure of LCB and to isolate the lignocellulosic components in pure form, pretreatment is a crucial process in the bio-refinery, ensuring the economic feasibility of downstream processes. This review provides an outline of the structure, composition, and various sources of LCB; and the necessity of the pretreatment. Moreover, this article provides an in-depth analysis of the underlying mechanisms, advantages, and limitations of various pretreatment methods, such as physical, chemical, biological, and physicochemical. Further, the impact of chemical pretreatment techniques on the physicochemical characteristics of the material that is extracted from the biomass is also covered in detail through the rigorous evaluation of performance metrics, including substrate digestibility, sugar yield, inhibitor production, and energy requirements. This review provides a balanced and comprehensive overview of the state-of-the-art pretreatment strategies and their impact on biomass valorisation that will be useful to the scientists, engineers, and policy makers interested in biomass conversion technologies.

A bifunctional catalyst from waste eggshells and its application in biodiesel synthesis from waste cooking oil

Improvement in biofuel synthesis technology could facilitate widespread utilization of biodiesel, and an efficient operation in terms of cost. Catalyst enhancement through mineralization of waste biogenic material is vital for biodiesel production. In this study, biodiesel production was from waste cooking oil (WCO) using a bifunctional catalyst synthesized from waste eggshells and ferric sulfate. The CaO precursor developed from calcined eggshell at 800 °C for 3 h was impregnated with ferric sulfate at a ratio of 1:1. The Bifunctional catalyst synthesized was characterized using an X-ray diffractometer, scanning electron microscopy, Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis. The bifunctional catalyst was applied in a one-pot reaction of WCO and methanol to produce biodiesel. The reaction was modeled using the Taguchi orthogonal array design to maximize biodiesel production. The heterogeneous catalyst contained Ca (20.7 %), Fe (18.5 %), S (4.5 %), and O (54.8 %). The identified crystalline phases are CaSO4/Fe2O3 and CaSO4.0.5H2O/Fe2O3. A maximum biodiesel yield of 89.94 wt% was observed under the operating conditions of methanol/oil molar of 5:1, time of 45 min, temperature of 70 °C, and catalyst amount of 4 wt%. The reusability of the catalyst was established for (four) 4 cycles without further treatment. The synthesized biodiesel met the standard specifications. Hence, the synthesized catalyst proved effective in the transesterification of oil with a moderately high free fatty acid, thereby the bifunctional catalyst could expedite biodiesel production from waste cooking oil, and this biofuel could serve as fuel in powering diesel engines.

A mini‐review of intensified synthesis of 1st and 2nd generation biofuels in the presence of perovskite catalysts

AbstractEnhancement of a sustainable environment through the choice of a selective catalyst with high activity, regeneration nature, and high stability is an important aspect to be focused on to achieve a high yield and maximum conversion of feedstock to biodiesel (1st generation biofuel), and also in the biomass valorization/pyrolysis (2nd generation biofuel synthesis). Depending on the nature of the catalyst and synthesis method adopted for biofuel production and biomass valorization, the variations in the process conditions, final yield, and conversion are varied accordingly. A prospective development and application of perovskite catalysts in the synthesis of 1st and 2nd generation biofuels using various process intensification strategies for the development of a clean and green environment is reviewed in this study. The synthesis of types of perovskite catalysts polycrystalline, nano‐sized, and powdered oxide are also discussed in this review. It is also concluded that, apart from other process parameters, molar ratio is one of the most influencing sensitive factors in the case of 1st generation biofuel synthesis, whereas during the production of 2nd generation biofuels, catalyst concentration and liquid–solid ratio are more significant process parameters that change based on the nature of the catalyst selected for the reaction.

Microbial Induced Biotechnological Processes for Biofuel Production from Waste Organics Conversion

In the current era there are huge quantities of waste organic matter available, creating a big burden to the environment. To address these issues, researchers started to apply effective and microbial induced biotechnological processes that can mitigate these waste matters. In this context, different nature of microbial systems are involved in hydrolysing the waste organic material into fermentable sugar. These can be easily consumed by specific microbial systems like Saccharomyces cerevisiae MTCC 3821 and Clostridium acetobutylicum that produced bioethanol and biobutanol, respectively. Saccharomyces cerevisiae was cultured in specific media and incubated at rotary shaker with 150 rpm at 30°C for 72 to 96 hours. Ethanol concentrations from different waste matters were found in the range of 1.2-1.5 g.L-1. Ethanol synthesis was done by shake flask experiment with addition of glucose (50 g.L-1) to waste organic hydrolyzed solution. Non-glucose media produced less than 3 g.L-1 ethanol but glucose media produced 4.5 g.L-1. Next, Clostridium acetobutylicum was grown in culture media containing waste organics as sole carbon substrate with pH 7 and then was incubated in anaerobic conditions at 35°C for 72 hours, produced butanol (0.7 to 1.25 g.L-1). This research work promoted biofuels synthesis by keeping a waste mitigation strategy.

Intensification of valorization of cooked rice water through energy-efficient synthesis of drop-in biofuel (butyl levulinate): engine performance, emission profile, and environmental impact assessments.

For the first time, an energy-efficient and eco-friendly technology for the conversion of abundantly available kitchen waste, specifically waste cooked rice water (WCRW) to drop-in- biofuels, namely, butyl levulinate (BL), has been explored. The synthesis of BL was accomplished employing butyl alcohol (BA) and WCRW in an energy-efficient UV (5W each UVA and UVB)-near-infrared (100W) irradiation assisted spinning (120rpm) batch reactor (UVNIRSR) in the presence of TiO2-Amberlyst 15 (TA15) photo-acidic catalyst system (PACS). The optimal 95.81% yield of BL (YBL) could be achieved at 10 wt% catalyst concentration, 60°C reaction temperature, 80min time, and 1:10 WCRW: BA concentration as per Taguchi statistical design. Moreover, additional combination of different PACS such as TiO2-Amberlyst 16, TiO2-Amberlyst 36, and TiO2-Amberlite IRC120 H rendered 86.72% YBL, 90.04% YBL, and 93.47% YBL, respectively, proving superior efficacy compared to individual activity of the acidic catalysts and photocatalysts. The heterogeneous reaction kinetics study for TA15 PACS suggested Langmuir-Hinshelwood model to be the best fitted model. A significant 63.33% energy could be saved by UVNIRSR as compared to conventional heated reactor at the optimized experimental condition using PACS TA15. An overall alleviation in environmental pollution with 59.259% reduction in GWP, 15.254% decline in terrestrial ecotoxicity, 18.238% diminution in marine ecotoxicity, 17.25% decrease in ozone formation affecting human health, 5.865% reduction in human non-carcinogenic toxicity, 18.65% diminution in ozone formation affecting terrestrial ecosystem, 55.17% significant decrease in terrestrial acidification, and 25.619% mitigation in fresh water ecotoxicity could be observed. Furthermore, BL-biodiesel-diesel blends (3% BL, 7% biodiesel, and 90% diesel) exhibited significant reduction (25.45% and 36%, respectively, for CO and HC) in harmful engine exhaust emissions demonstrating environmental sustainability of the overall process.

Catalytic biodiesel production from Jatropha curcas oil: A comparative analysis of microchannel, fixed bed, and microwave reactor systems with recycled ZSM-5 catalyst

In this study, we studied the conversion of Jatropha curcas oil to biodiesel by using three distinct reactor systems: microchannel, fixed bed, and microwave reactors. ZSM-5 was used as the catalyst for this conversion and was thoroughly characterized. X-ray diffraction was used to identify the crystalline structure, Brunauer–Emmett–Teller analysis to determine surface area, and temperature-programmed desorption to evaluate thermal stability and acidic properties. These characterizations provided crucial insights into the catalyst's structural integrity and performance under reaction conditions. The microchannel reactor exhibited superior biodiesel yield compared to the fixed bed and microwave reactors, and achieved peak efficiency at 60 °C, delivering high FAEE yield (99.7%) and conversion rates (99.92%). Ethanol catalyst volume at 1% was optimal, while varying flow rates exhibited trade-offs, emphasizing the need for nuanced control. Comparative studies against microwave and fixed-bed reactors consistently favored the microchannel reactor, emphasizing its remarkable FAME percentages, high conversion rates, and adaptability to diverse operating conditions. The zig-zag configuration enhances its efficiency, making it the optimal choice for biodiesel production and showcasing promising prospects for advancing sustainable biofuel synthesis technologies.

Chromosome-level genome assembly of Euphorbia tirucalli (Euphorbiaceae), a highly stress-tolerant oil plant

Euphorbia, one of the largest genera of flowering plants, is well-known for containing many biofuel crops. Euphorbia tirucalli, an evergreen succulent mainly native to the Africa continent but cultivated worldwide, is a promising petroleum plant with high tolerance to drought and salt stress. However, the exploration of such an important plant resource is severely hampered by the lack of a reference genome. Here, we present the chromosome-level genome assembly of E. tirucalli using PacBio HiFi sequencing and Hi-C technology. Its genome size was approximately 745.62 Mb, with a contig N50 of 74.16 Mb. A total of 743.63 Mb (99.73%) of the assembled sequences were anchored to 10 chromosomes with a complete BUSCO score of 97.80%. Genome annotation revealed 26,304 protein-coding genes, and 76.37% of the genome was identified as repeat elements. The high-quality genome provides valuable genetic resources that would be useful for unraveling the genetic mechanisms of biofuel synthesis and evolutionary adaptation of E. tirucalli.

Integrated catalytic approach for advanced biofuel production from renewable ABE fermentation

This study focuses on advancing the production of sustainable aviation biofuels by employing a one-pot integrated catalytic approach to convert Clostridium beijerinckii strain SR-44 ABE fermentation products into higher-value compounds, specifically ketones, using Pd/Ni@BNNS bimetallic catalysts. The influence of various parameters, such as salting-out agents, temperature, catalyst loading, and reaction time, significantly improved the ABE conversion to 98% with 86% higher ketone (C5–C11) selectivity. Furthermore, the heterogeneity and recyclability of the Pd/Ni @BNNSs catalyst were investigated, confirming its suitability for industrial-scale applications. By advancing biofuel synthesis technology and overcoming the drawbacks of conventional biofuels, this study contributes to the mitigation of the environmental and energy challenges facing the aviation industry.

Synthesis of biofuel from Luffas cylindrical-Dennettia tripetala oil blend (BT40) using catalytic sweet corn stock acidified with iron (III) sulfate (Fe2(SO4)3)

In an attempt to model and optimize the biodiesel production from the binary oil blends, a BTO40 obtained from the mixture of Dennettia tripetala (DTO) and Luffas cylindrical (LCO) oilseeds was employed in a double-stage microwave-assisted batch process (DSMABP). The DTO40 was esterified with iron (III) sulfate (Fe2(SO4)3) and then transesterified with catalyst selectivity between calcined fermented sweet corn stock (CFCS) and calcined non-fermented sweet corn stock (CNFCS). Catalyst characterization was carried out using analyzers, while process modeling and optimization were carried out using statistical tools. The produced biodiesel qualities were evaluated, and the catalyst potential was tested by a catalyst reusability test. Results show that a BTO40 was suitable for maximum biodiesel yield of 98.92% (wt./wt.) with HHV of 43.84 MJ/kg, CN of 79.73, flash point of 120 °C, cloud point of -3 °C, pour point of -6 °C, cold filter plugging point of +2 °C, oxidative stability of 4.6 h, and carbon residue of 0.02% nm. The statistical modeling and optimization by RSMI-Optimal predicted a mean value of biodiesel to be 99.28% (wt./wt.), the ANNGA predicted a mean biodiesel yield of 99.78% (wt./wt.), and γGCFW predicted 99.82% (wt./wt.), respectively, at different variable conditions. These values were validated in triplicate, and the average means were obtained as 98.57% (wt./wt.), 99.69% (wt./wt.), and 99.71% (wt./wt.), respectively. Catalyst usability tests show DFSCS has high alkali potential as a base catalyst. The produced biodiesel properties are in total agreement with the recommended biodiesel standard. The study concluded that BTO40 treated with a 0.1 M Fe2(SO4)3 solution in a base-catalyzed calcined fermented sweet corn stock for biodiesel synthesis can be used as an alternative fuel.

Synthesis of sustainable aviation biofuels via catalytic hydropyrolysis of lignin

The exploitation of bimetallic catalysts to lignin for sustainable aviation biofuels remains a daunting challenge due to the low selectivity of aviation biofuel-range hydrocarbons and inconsistent reaction mechanism. Herein, bimetallic supported on SiO2 catalysts were prepared and their hydrodeoxygenation reactivity during lignin catalytic hydropyrolysis was explored. Approximately 100 % selectivity toward aviation-range hydrocarbons were achieved using eugenol as model compound under relatively mild conditions with the presence of NiMo/SiO2. For lignin catalytic hydropyrolysis, the yield of liquid hydrocarbons and the selectivity of aviation-range hydrocarbons was 21.99 wt% and 70.50 %, respectively. High mass balance (89.66 %) was verified by scale-up experiments in a continuous flow high-pressure reactor system. The reactivity of demethoxylation reaction, dehydroxylation reaction, and benzene ring hydrogenation reaction with the presence of bimetallic catalysts were analyzed. The density functional theory calculation and verification experiments revealed the evolution pathway of aromatic hydrocarbons and cycloalkanes from lignin catalytic hydropyrolysis. The proposed reaction mechanism can provide guidance for the regulation of aviation biofuel components from lignin catalytic hydropyrolysis.

Futuristic opportunities for pretreatment processes in biofuel production from microalgae

AbstractMicroalgal biofuel is a promising solution to replace fossil fuel as a renewable and environmental‐friendly energy source, thereby contributing to the United Nations (UN) Sustainable Development Goals (SDGs), in particular SDG‐7, or Affordable and Clean Energy. Unlike energy crops (like oil palm and sugar cane), microalgae benefit from faster growth rate, higher lipid content, smaller land area required, ability to flourish using waste or brackish water, and posing zero competition with food crops. Microalgae‐derived biofuels (like biodiesel, bioethanol, biomethane, and biohydrogen) are sustainable energy sources that can be produced using well‐developed techniques (e.g., transesterification, fermentation, anaerobic digestion, and Fisher–Tropsch process). To prevent dire climate conditions resulting from the global temperature rise of 1.5°C and resolve worldwide energy security issue, our generation will need to establish and implement renewables on a global scale. To improve the industrial production of microalgal biofuel, the efficiencies of biomass and metabolite production to post‐cultivation biofuel synthesis processes must be enhanced. For the cultivation step, there exist three key techniques that can directly change the traits, structure, and behavior of microalgal cells, and induce them to accumulate targeted metabolites rapidly and in large amounts. These techniques are genetic engineering, chemical modulation, and nanomaterial approach. Genetic engineering commonly alters the chloroplast DNA of microalgae to overexpress or down‐regulate key genes in various metabolic pathways so that the cells accumulate more lipids. Chemicals can also be used to modulate microalgal growth and lipid accumulation by inducing oxidative stress or prevent conversion of lipid molecules. Nanomaterials and nanoparticles can also enhance microalgal lipid production by microenvironmental stress induction, vitamin supplementation, and light backscattering. Therefore, in this review, the recent progress as well as the pros and cons of genetic engineering, chemical modulation, and nanomaterial approach in achieving greater biofuel production from microalgae are comprehensively examined.

Conversion of 5-hydroxymethylfurfural and carbohydrates to 5-ethoxymethylfurfural over chitin-derived solid acid catalysts

The use of environment friendly biomass-based catalysts in bio refinery is highly desirable. In this paper, the preparation of sulfonated carbon materials from biopolymers (typically chitin and cellulose) via facile one-step carbonization and sulfonation using p-toluenesulfonic acid as sulfonating agent was demonstrated. Unlike nitrogen-free cellulose, the basic nitrogen-containing sites generated from chitin decreased the acidity strength of the catalysts, which was confirmed by the results of 31P Nuclear Magnetic Resonance (31P NMR). The suppressed acidity strength boosted the selectivity of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) by inhibiting the formation of by-products, such as ethyl levulinate (EL) and humins. An 84.3 % yield of EMF from HMF was obtained over the as-prepared chitin-derived solid acid. The catalyst could be reused at least three times without obvious decrease of catalytic activity. Moreover, 74.6 %, 31.9 % and 60.7 % yields of EMF were obtained from fructose, sucrose and inulin in ethanol-containing solvents, respectively. This work offers an example for the synthesis of biofuels using biomass-derived catalysts.

Production of Renewable Hydrocarbon Biofuels with Lignocellulose and Its Derivatives over Heterogeneous Catalysts.

In recent years, the issues of global warming and CO2 emission reduction have garnered increasing global attention. In the 21st Conference of the Parties (convened in Paris in 2015), 179 nations and the European Union signed a pivotal agreement to limit the global temperature increase of this century to well below 2 K above preindustrial levels. To fulfill this objective, extensive research has been conducted to use renewable energy sources as potential replacements for traditional fossil fuels. Among them, the production of hydrocarbon transportation fuels from CO2-neutral and renewable biomass has proven to be a particularly promising solution due to its compatibility with existing infrastructure. This review systematically summarizes research progress in the synthesis of liquid hydrocarbon biofuels from lignocellulose during the past two decades. Based on the chemical structure (including n-paraffins, iso-paraffins, aromatics, and cycloalkanes) of hydrocarbon transportation fuels, the synthesis pathways of these biofuels are discussed in four separate sections. Furthermore, this review proposes three guiding principles for the design of practical hydrocarbon biofuels, providing insights into future directions for the development of viable biomass-derived liquid fuels.

A Study of Green Synthesis of Nano-TiO2 Catalyst by Gossypium Leaf Extract and Its Nanocatalysis in the Synthesis of Biofuel from Gossypium Seed Oil

Synthesis of TiO2 nanoparticles by aqueous leaf extract of Gossypium (Gossypiumarboretum) leaves on meta titanic acid [TiO(OH)2]. Rutile tetragonal TiO2 nanoparticles were characterized by XRD, SEM and TEM studies and their particle size was calculated, which was below 100 nm. The Obtained TiO2NPs were used as catalysts in the transesterification of Gossypium seed oil, which enhanced the rate of reaction. Thus, it is a very attractive catalyst for biodiesel production from Gossypium seed oil. The effect of the amount of nano-TiO2 catalyst and microwave heating was studied. In this study, the preparation of both catalyst and biodiesel from the parts of the same Gossypium plant and the feasibility of carrying out the microwave-assisted transesterification (green process) of Gossypium seed oil by using biogenic nanoTiO2 catalyst was explored. They improve the efficiency of transesterification. The used catalyst can be recycled by simple filtration and reused without reduction in its activity. It is a green method (affords nontoxic and noncorrosive medium), clean reaction, simple experimental, isolation procedures, gives high yield and the properties of synthesized biodiesel are in good agreement with that of diesel oil. So, it may be used alone or by blending with diesel.

Supercritical ethanol-assisted catalytic upgrading of bio-tar using mesoporous SBA-15 supported Ni-based catalysts

The bio-tar transformation was conducted utilizing Ni-based catalysts supported on mesoporous SBA-15 within a supercritical ethanol environment. This approach aimed to facilitate the synthesis of biofuels and/or value-added chemical compounds, including alkyl phenols and aromatics. The characterization of the catalysts was accomplished by X-ray diffraction (XRD), N2-sorption, temperature programmed reduction (TPR), Transmission electron microscope (TEM), and Fourier Transform Infrared (FT-IR) techniques. Among the examined catalysts, namely SBA-15, Ni/SBA-15, Ni–Mo/SBA-15, and Mg–Ni–Mo/SBA-15, Mg–Ni–Mo/SBA-15 emerged as the catalyst demonstrating the most pronounced activity for the hydrodeoxygenation (HDO) of bio-tar to produce high-quality liquid products (Total Acid Number (TAN): 3.4 mgKOHg−1, oxygen content: 11.0 wt%, Higher heating value (HHV): 36.7 MJkg−1). The effect of reaction temperature (275–350 °C) and time (0–120 min) on the upgrading of bio-tar over Mg–Ni–Mo/SBA-15 was investigated in a one-pot process. The acids, aldehydes, and oxygenated phenols underwent complete conversion into chemically more stable compounds such as aromatics and alkyl phenols at 325 °C for a 120 min holding time. In particular, the oxygenated phenols found in the bio-tar underwent a complete transformation into alkyl phenols within the liquid products.