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Summary: Lithium orthosilicate (Li4SiO4) is a promising solid catalyst for biodiesel synthesis. However, Li4SiO4 is traditionally prepared by a solid‐state reaction, which results in the unstable activity for the reaction. In the present study, Li4SiO4 was successfully prepared using a simple sol‐gel method and employed as an efficient solid alkali catalyst for biodiesel synthesis. The molar ratio of precursors and calcination temperature were optimized for the synthesis of Li4SiO4 by using the sol‐gel method. The physical and chemical properties were determined using X‐ray diffraction, scanning electron microscopy, laser diffraction particle size, and thermogravimetric analysis. The as‐prepared Li4SiO4 catalyst had much smaller particle size, pore volume, and pore size, but higher surface area and basicity than Li4SiO4 catalyst prepared by the solid‐state reaction. It was then used to transesterify methanol and soybean oil into biodiesel. The effect of reaction factors (reaction time from 1 to 3 hours, catalyst concentration from 3 to 9%; molar ratio of methanol to oil from 6:1 to 18:1, and temperature from 55°C to 75°C) on the Li4SiO4‐catalyzed transesterification was systematically examined. The highest biodiesel conversion of 91% was reached under the following conditions: reaction time of 2 hours, Li4SiO4 concentration of 6%, 12:1 methanol:oil molar ratio, and temperature of 65°C. Notably, Li4SiO4 could be efficiently reused for at least 10 times without significant loss of its activity; this suggests that the sol‐gel synthesized Li4SiO4 is a potential solid alkali catalyst for biodiesel synthesis. [ABSTRACT FROM AUTHOR]

Microalgae has received overwhelming attention worldwide as a sustainable source for energy generation. However, the production of biofuel from microalgae biomass consists of several steps, of which lipid extraction is the most important one. Because of the nature of feedstock, extraction needs special attention. Three different methods were studied to extract algal oil from two different algae variant, Chlorella sp. and Spirulina sp. The highest percentage oil yield was obtained by ultrasonication (9.4% for Chlorella sp., 6.6% for Spirulina sp.) followed by the Soxhlet and solvent extraction processes. Ultrasonication and Soxhlet extraction processes were further optimized to maximize oil extraction as solvent extraction was not effective in extracting lipid. For ultrasonication, an amplitude of 90% recorded the highest percentage yield of oil for Spirulina sp. and a 70% amplitude recorded the highest percentage yield of oil for Chlorella sp. On the other hand, for Soxhlet extraction, a combination of chloroform, hexane, and methanol at a 1:1:1 ratio resulted in the highest yield of algal oil. Afterward, the crude algae oil from the ultrasonication process was transesterified for 5 h using an immobilized lipase (Novozyme 435) at 40 °C to convert triglycerides into fatty acid methyl ester and glycerol. Thus, ultrasonic-assisted lipid extraction was successful in producing biodiesel from both the species. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel modeling approach (artificial neural networks (ANN) and ant colony optimization (ACO)) was used to optimize the process variables for alkaline-catalyzed transesterification of CI40CP60 oil mixture (40 wt% of Calophyllum inophyllum oil mixed with 60 wt% of Ceiba pentandra oil) in order to maximize the biodiesel yield. The optimum values of the methanol-to-oil molar ratio, potassium hydroxide catalyst concentration, and reaction time predicted by the ANN-ACO model are 37%, 0.78 wt%, and 153 min, respectively, at a constant reaction temperature and stirring speed of 60 °C and 1000 rpm, respectively. The ANN-ACO model was validated by performing independent experiments to produce the CI40CP60 methyl ester (CICPME) using the optimum transesterification process variables predicted by the ANN-ACO model. There is very good agreement between the average CICPME yield determined from experiments (95.18%) and the maximum CICPME yield predicted by the ANN-ACO model (95.87%) for the same optimum values of process variables, which corresponds to a difference of 0.69%. Even though the ANN-ACO model is only implemented to optimize the transesterification of process variables in this study. It is believed that the model can be used to optimize other biodiesel production processes such as seed oil extraction and acid-catalyzed esterification for various types of biodiesels and biodiesel blends. Graphical abstract Image 1 Highlights • CICPO is a potential feedstock for biodiesel production. • ANN-ACO is a reliable tool to optimize the transesterification process variables. • Methanol-to-oil molar ratio has the most significant effect on the CICPME yield. • The optimum CICPME yield predicted by the ANN-ACO model is 95.87%. • The optimum CICPME yield obtained from independent experiments is 95.18%. [ABSTRACT FROM AUTHOR]

Rapidly increasing global energy consumption has caused depletion of fossil fuels, leading to the search of alternative energy resources. One of the potential solutions is utilizing algae biomass as the source of bioenergy. To fulfil the high biomass demands for biofuel production, it is of pivotal importance to develop feasible technologies to enable economic, efficient and high density cultivation of algae. Algae can be cultivated in either open or closed systems in the presence of nutrients and light intensity. The maximum yield, growth rate and composition of algae can be optimized according to cultivation conditions, such as temperature, pH, light intensity and nutrient concentration. The potential types of algae in contributing carbohydrate and lipids to produce biofuel such as biodiesel, bioethanol and bio-gas are reviewed. Economic feasibilities of algae based fuel production are discussed based on Life Cycle Analysis. Current challenges and future prospective are also presented to realize the use of algae as a feedstock for commercial and cost effective fuel production. [ABSTRACT FROM AUTHOR]

Esterification is required to reduce the high free fatty acid (FFA) content of crude Jatropha oil to below 3% prior to transesterification. In this study, raw decorticated Jatropha seeds were employed as the feedstock in in situ reactive extraction assisted by ultrasound in the presence of sulfuric acid (H2SO4) as a catalyst. Extraction efficiency, esterification efficiency, and fatty acid methyl ester (FAME) yield were optimized as a function of ultrasonic pulse mode, amplitude, and H2SO4 amount. The optimum extraction efficiency of 83.96%, esterification efficiency of 71.10%, and FAME yield of 38.58% were achieved at a pulse mode of 5 s on/2 s off, an ultrasonic amplitude of 60%, and an H2SO4 amount of 5 mL in reaction time of 150 min. [ABSTRACT FROM AUTHOR]

Environmental pollution and the declining global supply of accessible fossil fuels are the key drivers of the search for alternative sources of energy. Biodiesel, a renewable liquid transport fuel, is commercially-produced using heterogeneous catalysts. Heterogeneous catalysts obtained from seashells appeared as promising alternatives thanks to their low preparation cost and increased efficiency in transesterification. In this study, shells from Chicoreus brunneus (known as Adusta murex ) were calcined, hydrated, and dehydrated to produce CaO heterogeneous nanocatalyst for the transesterification of rice bran oil into biodiesel. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, surface area measurement (Brunauer-Emmett-Teller method), and X-ray diffraction were used to characterise the seashell-derived catalyst. The properties of the rice bran oil-derived biodiesel (acid value, calorific value, density, oxidation stability, and flash point) conformed to the American Society of Testing and Materials (ASTM) D6751 and European EN 14214 biodiesel standards, except for kinematic viscosity. Therefore, the impact of the parameters used for production of the CaO heterogeneous nanocatalyst (calcination temperature and time) and the transesterification reaction (catalyst loading and methanol to rice bran oil ratio) on the kinematic viscosity of RBO-derived biodiesel were determined. A model for the transesterification process was developed using a combination of artificial neural networking with ant colony optimisation. The model predicted that C. brunneus -derived CaO catalyst prepared at 1100 °C for 72 min could be used to produce biodiesel from rice bran oil with a minimum kinematic viscosity (4.42 mm 2 s −1 ) confirming to both the ASTM D6751 and EN 14214 biodiesel standards in a transesterification reaction operating with a 35:1 methanol to rice bran oil molar ratio and 0.5 wt% catalyst mass. [ABSTRACT FROM AUTHOR]

In this study, a carbon-based solid acid catalyst was prepared using the de-oiled Jatropha curcas (JC) seed cake waste. The catalyst was consequently used to esterify the JC oil in order to lower the high free fatty acid content (FFA) to an acceptable level (<4 mg KOH g −1 ) for biodiesel production. The chemical and physical properties of the catalyst were characterized using a variety of techniques. The conversion of FFA reached 99.13% under optimum conditions of 12:1 methanol/oil molar ratio, 7.5 wt% catalyst loading, 60 min reaction time and 60 °C reaction temperature at 350 rpm. The catalyst was also determined to outperform the conventionally used sulfuric acid catalyst in terms of reaction time needed to achieve the highest conversion yield. The high catalytic ability of the catalyst was associated with the high acid site density formed in the catalyst which was due to the high porosity and large pore size of the carbon framework of the catalyst. The hydrophobic nature of the catalyst also contributed to the stability of the catalyst in which it can be re-used up until the 4th cycle. The recyclability of the catalyst and its cheap feedstock makes the overall process much simpler, cost-efficient and environment-friendly. [ABSTRACT FROM AUTHOR]

Biodiesel production fromCeiba pentandraoil using immobilizedCandida antarcticalipase (Novozym 435) was studied. A drastic change from 20.6% to 78.0% yield for 9:1 methanol to oil molar ratio indicated the significance of methanol stepwise addition method. Tests were done on the effect of enzyme pretreatments to biodiesel yield productivity which resulted in increase of yield when using t-butanol but decreased yield when using sodium chloride solution. The reusability of enzyme was measured at 63.7% relative yield after three batches. Biodiesel production fromC. pentandraoil using biocatalyst is feasible and can be improved for industrialization. [ABSTRACT FROM PUBLISHER]

In this study, biodiesel production using ultrasound and infrared techniques is introduced. The ultrasound and infrared techniques are more efficient for biodiesel production since they improve the mass transfer between the immiscible reactants, increase chemical reactions, and decrease the reaction time and energy consumption. The effect of the reaction time on the acid value of the esterifiedSterculia feotidaoil is also investigated and it is found that the acid value is 0.76 and 0.85 mg KOH/g for the ultrasound and infrared technique, respectively, at a reaction time of 60 min. In addition, it is found that the biodiesel yield obtained from the ultrasound technique is higher (99.41%) compared to the infrared technique (98.55%) at a reaction time of 60 min. The KOH catalyst is analyzed for both of these techniques and it is found that the ultrasound technique gives faster absorbed reaction compared to the infrared technique. Hence, it can be concluded that the ultrasound and infrared transesterification techniques are promising techniques for biodiesel production. [ABSTRACT FROM AUTHOR]

Microalgae are promising alternative plant sources for biodiesel production because of the significant increase in lipid yield through heterotrophic cultivation and genetic engineering approaches. This study aims to evaluate the extraction and conversion of lipids fromIsochrysis galbana. Response surface methodology (RSM) was used to optimize lipid extraction and thereby obtain high yields from the four microalgae species. The optimal lipid yields forIsochrysis galbanais 8.41 wt%. Moreover, the dominant lipid composition found fromIsochrysis galbanaextractions was palmitic acid (C16:0) at 22.3%. The high saturated acid ofIsochrysis galbanacontributed to the improved biodiesel properties because biodiesel quality is influenced by the lipid composition of microalgae species. The study employed the two-step esterification–transesterification process to convert the microalgae oil into biodiesel, glycerol, and water. The FAME content is 99.7% under the methanol to oil molar mass of 12:1, 1 wt%, 65°C, and 800 rpm. Furthermore, the main biodiesel properties, such as viscosity, higher heating value, and iodine value, were measured according to ASTM D6751 and EN 14124. Results show that microalgae oil can potentially be used as biofuel in future applications. [ABSTRACT FROM AUTHOR]

The increasing global demand for fuel, limited fossil fuel resources, and increasing concern about the upturn in gaseous CO 2 emissions are the key drivers of research and development into sources of renewable liquid transport fuels, such as biodiesel. In the present work, we demonstrate biodiesel production from Ocimum basilicum (sweet basil) seed oil by lipase-catalyzed transesterification. Sweet basil seeds contain 22% oil on a dry weight basis. Artificial neural network with genetic algorithm modelling was used to optimize reaction. Temperature, catalyst concentration, time, and methanol to oil molar ratio were the input factors in the optimization study, while fatty acid methyl ester (FAME) yield was the key model output. FAME composition was determined by gas chromatography mass spectrometry. The optimized transesterification process resulted in a 94.58% FAME yield after reaction at 47 °C for 68 h in the presence of 6% w/w catalyst and a methanol to oil ratio of 10:1. The viscosity, density, calorific value, pour point, and cloud point of the biodiesel derived from sweet basil seed oil conformed to the EN 14214 and ASTM D6751 standard specifications. The antioxidant stability of the biodiesel did not meet these specifications but could be improved via the addition of antioxidant. [ABSTRACT FROM AUTHOR]

The research on biodiesel production via heterogeneous catalyzed approach is continuously studied by scientist in order to gain a sustainable process for industrial production and to improve its fuel quality. The green resource of biodiesel feedstock and catalyst is the major criteria to influence the biodiesel yield and sustainability of the process. For the state of the art biodiesel production technology, heterogeneous catalyst received great attention for simple and low cost manufacturing process. In terms of easy separation and high reusability. The most special characteristic of heterogeneous catalyst is its tuning properties that generate acidic-basicity, surface area and porosity that can highly advance the variety of the feedstock for esterification/transesterification process. Different traits of the heterogeneous catalysts (solid base, solid acid, acid-base and bio-catalyst) are studied in this review as each holds a specialty of features to the process. Thus, the study of heterogeneous catalyst should continue to be evaluated and taken into account if the catalyst are to be employed in the commercial sector as that remains the pivotal goal of these studies. In consideration to the debate of food vs. fuel as well as low cost production, non-edible feedstock was further discussed by using heterogeneous catalyzed system. [ABSTRACT FROM AUTHOR]

The realization of declining fossil fuel supplies and the adverse impact of fossil fuels on the environment has accelerated research and development activities in renewable energy sources and technologies. Biofuels are renewable fuels made from edible, non-edible or waste oils, as well as animal fats and algae, and these fuels have been proven to be good substitutes for fossil fuels in the transportation sector. Bioethanol and biodiesels have gained worldwide attention in order to address environmental issues associated with fossil fuels, provide energy security, reduce imports and rural employment, as well as improve agricultural economy. Bioethanol has high oxygen content and octane content up to 35% and 108, respectively and hence, it increases oxygenation and improves combustion of fuel. In addition, bioethanol has lower vaporization pressure, which reduces the risks associated with evaporative emissions. In contrast, biodiesel has good lubricity, which helps protect the surface of engine components from wear and friction. The use of biodiesel–bioethanol–petroleum diesel blends poses a greater challenge with regards to improving the compatibility of the materials with the fuel system in compression ignition (CI) and spark ignition (SI) engines. In this work, the technical conditions of an engine ( i.e. engine deposits, wear of the engine components and quality of the lubrication oil) are assessed by the application of with biodiesel–bioethanol–petroleum diesel blends. It is deemed important to evaluate the effects of using bioethanol and biodiesels in diesel engines. This paper provides insight on the feasibility of biodiesel and bioethanol feedstocks, the compatibility of biodiesels, bioethanol and their blends with diesel engines as well as the physicochemical properties of these fuels. [ABSTRACT FROM AUTHOR]

Biodiesel is a renewable energy that has great potential as an alternative fuel to fossil diesel in diesel engine. The potential non-edible feedstock for biodiesel is now being taken into careful consideration for the purpose of continuing biodiesel production while not negatively affecting the food issue. The crude jatropha curcas , calophyllum inophyllum and ceiba pentandra oil have free fatty acid value which is above 2%. Therefore, a pretreatment acid catalyzed esterification process is required to reduce the free fatty acid content. It was found that jatropha curcas , calophyllum inophyllum and ceiba pentandra oil at 9:1 M ratio (methanol to oil) with preheat at 60 °C and reaction at temperature 55 °C for 60 minutes in the presence of 1% KOH in order to get lower acid values (0.39 mg KOH/g, 0.45 mg KOH/g and 0.40 mg KOH/g) and obtained high methyl ester yield (98.23%, 98.53% and 97.72%). This study had shown that improvement in biodiesel properties by using two stage esterification-transesterification methods. The major fuel characteristics such as kinematic viscosity, density, flash point and calorific value of biodiesel fulfilled American Society for Testing Materials (ASTM) biodiesel standards. [ABSTRACT FROM AUTHOR]

Biodiesel from vegetable oils has attracted a great deal of interest as a alternative fuel for fossil diesel. This effort able to reduce the dependence on petroleum based fuels and provides a fuel with more benign environmental. Non-edible vegetable oils are attracting more attention than edible oils due to the concern on food versus fuel and other environmental issues. Cerbera manghas oil is one of the promising non-edible feedstocks. Biodiesel production from cerbera manghas vegetable was first time reported and investigated. The viscosity of crude oil was 32.83 mm 2 /s and 12.64 mg KOH/g for acid value which is far above the 2%. Therefore, cerbera manghas methyl ester (CMME) was produced via two step acid-alkaline transesterification using H 2 SO 4 as acid catalyst and KOH as alkaline catalysts. Hence 98.5% of biodiesel was achieved with 9:1 methanol in presence of 1% sodium hydroxide. Moreover, blending of CCME with diesel resulted in an improvement which the viscosity is reduced to 3.54 mm 2 /s. On the other hand, the blending of CMME also shown the remarkable improvement in oxidation stability (14.55 hours). The properties of cerbera manghas methyl ester fell within the recommended biodiesel standards. It can be conclude that cerbera manghas oil is promising feedstock for future production of biodiesel [ABSTRACT FROM AUTHOR]

Increasing number of population, advanced technology and economics growth somehow has caused energy depletion. The development of biofuel such as biodiesel, bioethanol and biogas is extremely needed to overcome these crises. Biofuel is derived from biological sources or biomass which are more environmental friendly, less toxic, reduce greenhouse gas emission and less cost. Algae comes from the third generation product of both biodiesel and bioethanol. Algae based biofuel has various advantages such as non-toxic, does not require fresh water to grow, higher growth rate, biodegradable and not used arable land. Thus, this review summarizes enzymatic reaction for production of all biofuels; biodiesel and bioethanol. The enzymatic reaction is safe, less contaminating and seems to produce higher yield of biofuel compared to chemical reaction. Overall finding of this study suggests that immobilization method and efficiency of the enzyme is the main factor in biofuel production. Finally, further studies are recommended to overcome the major constraint of high enzyme cost by improving the immobilization technique and processes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Calophyllum inophyllum has been evaluated as a potential feedstock for biodiesel. [•] Acid and base catalyzed transesterification processes was used to produce biodiesel. [•] The physiochemical properties of CIME fulfilled specification of ASTM D6751. [•] Engine performance and emission are conducted for CIME and its blends. [ABSTRACT FROM AUTHOR]

Abstract: Biodiesel is a recognized replacement for diesel fuel in compressed ignition engines due to its significant environmental benefits. The purpose of this study is to investigate the engine performance and emissions produced from Jatropha curcas, Ceiba pentandra and Calophyllum inophyllum biodiesel in compressed ignition engine. The biodiesel production process and properties are discussed and a comparison of the three biodiesels as well as diesel fuel is undertaken. After that, engine performance and emissions testing was conducted using biodiesel blends 10%, 20%, 30% and 50% in a diesel engine at full throttle load. The engine performance shows that those biodiesel blends are suitable for use in diesel engines. A 10% biodiesel blend shows the best engine performance in terms of engine torque, engine power, fuel consumption and brake thermal efficiency among the all blending ratios for the three biodiesel blends. Biodiesel blends have also shown a significant reduction in CO2, CO and smoke opacity with a slight increase in NO x emissions. [Copyright &y& Elsevier]

Biodiesel is a promising alternative to fossil fuels and mainly produced from oils/fat through the (trans)esterification process. To enhance the reaction efficiency and simplify the production process, various catalysts have been introduced for biodiesel synthesis. Recently, the use of bio-derived catalysts has attracted more interest due to their high catalytic activity and ecofriendly properties. These catalysts include alkali catalysts, acid catalysts, and enzymes (biocatalysts), which are (bio)synthesized from various natural sources. This review summarizes the latest findings on these bio-derived catalysts, as well as their source and catalytic activity. The advantages and disadvantages of these catalysts are also discussed. These bio-based catalysts show a promising future and can be further used as a renewable catalyst for sustainable biodiesel production. [ABSTRACT FROM AUTHOR]

Compression ignition engines play a significant role in the development of a country. They are widely used due to their innate properties such as high efficiency, high power output, and durability. However, they are considered one of the key contributors to transport-related emission and have recently been identified as carcinogenic. Thus, it is important to modify the designs and processes before, during, and after combustion to reduce the emissions to meet the strict emission regulations. The paper discusses the pros and cons of different strategies to reduce emissions of a diesel engine. An overview of various techniques to modify the pre-combustion engine design aspects has been discussed first. After that, fuel modifications techniques during combustion to improve the fuel properties to reduce the engine-out emission is discussed. Finally, post-combustion after-treatment devices are briefly discussed, which help improve the air quality of our environment. [ABSTRACT FROM AUTHOR]

The dwindling of global petroleum deposits and worsening environmental issues have triggered researchers to find an alternative energy such as biodiesel. Biodiesel can be produced via transesterification of vegetable oil or animal fat with alcohol in the presence of a catalyst. A heterogeneous catalyst at an economical price has been studied widely for biodiesel production. It was noted that various types of natural waste shell are a potential calcium resource for generation of bio-based CaO, with comparable chemical characteristics, that greatly enhance the transesterification activity. However, CaO catalyzed transesterification is limited in its stability and studies have shown deterioration of catalytic reactivity when the catalyst is reused for several cycles. For this reason, different approaches are reviewed in the present study, which focuses on modification of waste-shell derived CaO based catalyst with the aim of better transesterification reactivity and high reusability of the catalyst for biodiesel production. The catalyst stability and leaching profile of the modified waste shell derived CaO is discussed. In addition, a critical discussion of the structure, composition of the waste shell, mechanism of CaO catalyzed reaction, recent progress in biodiesel reactor systems and challenges in the industrial sector are also included in this review. [ABSTRACT FROM AUTHOR]

This study developed a microwave-mediated noncatalytic esterification of oleic acid for producing ethyl biodiesel. The microwave irradiation process outperformed conventional heating methods for the reaction. A highest reaction conversion, 97.62%, was achieved by performing esterification with microwave irradiation at a microwave power of 150 W, 2:1 ethanol:oleic acid molar ratio, reaction time of 6 h, and temperature of 473 K. A second-order reaction model (R2 of up to 0.997) was established to describe esterification. The reaction rate constants were promoted with increasing microwave power and temperature. A strong linear relation of microwave power to pre-exponential factors was also established, and microwave power greatly influenced the reaction due to nonthermal effects. This study suggested that microwave-assisted noncatalytic esterification is an efficient approach for biodiesel synthesis. [ABSTRACT FROM AUTHOR]

The production of biodiesel using vegetable oil is an effective way to meet growing energy demands, which could potentially reduce the dependency on fossil fuels. The aim of this study was to evaluate grape seed (Vitis vinifera), Philippine tung (Reutealis trisperma), and kesambi (Schleichera oleosa) oils as potential feedstocks for biodiesel production to meet this demand. Firstly, biodiesels from these oils were produced and then their fatty acid methyl ester profiles and physicochemical properties were evaluated and compared with palm biodiesel. The results showed that the biodiesel produced from grape seed oil possessed the highest oxidation stability of 4.62 h. On the other hand, poor oxidation stability was observed for Philippine tung biodiesel at 2.47 h. The poor properties of Philippine tung biodiesel can be attributed to the presence of α-elaeostearic fatty acid. Furthermore, synthetic antioxidants (pyrogallol) and diesel were used to improve the oxidation stability. The 0.2 wt.% concentration of pyrogallol antioxidant could increase the oxidation stability of grape seed biodiesel to 6.24 h, while for kesambi and Philippine tung, biodiesels at higher concentrations of 0.3% and 0.4 wt.%, respectively, were needed to meet the minimum limit of 8 h. The blending of biodiesel with fossil diesel at different ratios can also increase the oxidation stability. [ABSTRACT FROM AUTHOR]

• Different types of intermediate reactions of hydroprocessing pathway were compared. • Single step hydroprocessing of biofuel are mainly done by deoxygenation. • Ni-impregnated zeolite catalyst favors the yielding of biofuel in deoxygenation. • Optimum reacting parameters of deoxygenation are kept at 350–400 °C and 1–5 MPa. Present-day, commercial airlines are getting into the use of bio-jet fuel, by blending vegetable oil derived bio-jet fuel with fossil jet fuel in maximum up to 50%, which is ASTM-certified. In order to reduce the dependency on fossil jet fuel, recent research trend shows that most of the renewable aviation fuel or bio-jet fuel were derived from the complex liquid biomass via hydroprocessing technology. Hence there is a necessity to have an insight into the production technology, typically the hydroprocessing technology. Generally, hydroprocessing technology for the liquid biomass conversion into bio-jet fuel involved multi intermediate steps, such as deoxygenation, cracking and isomerization. This conventional process is further upgraded and simplified into single step reaction, which minimizes the post-treatment effort to be done in every reaction step, and thus reduces the production cost. Moreover, other economic factors such as catalyst price, hydrogen production cost and plant size will also consider as major impacts towards biofuel production scale and cost. Therefore, this paper aims to review the bio-jet fuel conversion technologies in a different perspective, by comparing the hydroprocessing technology of bio-jet fuel (i.e. three-step process, two-step process, single step process), and the effect of reaction variables (i.e. feedstock, catalyst, and reacting gas). The details of outputs for different hydroprocessing technology are also discussed herein. In summary, most research works have achieved positive findings in single step process, by adapting hydrodeoxygenation process in majority. However, there are some limitation and challenges that can be further improved in the single step process, such as exploration on potential feedstock, development of catalyst and optimization of reacting parameters. The energy, environmental and economic analysis on the advanced hydroprocessing of bio-jet fuel are yet to be conducted, in order to compare their merits. [ABSTRACT FROM AUTHOR]

Optimizing the process parameters of biodiesel production is the key to maximizing biodiesel yields. In this study, artificial neural network models integrated with ant colony optimization were developed to optimize the parameters of the two-step Cerbera manghas biodiesel production process: (1) esterification and (2) transesterification. The parameters of esterification and transesterification processes were optimized to minimize the acid value and maximize the C. manghas biodiesel yield, respectively. There was excellent agreement between the average experimental values and those predicted by the artificial neural network models, indicating their reliability. These models will be useful to predict the optimum process parameters, reducing the trial and error of conventional experimentation. The kinetic study was conducted to understand the mechanism of the transesterification process and, lastly, the model could measure the physicochemical properties of the C. manghas biodiesel. [ABSTRACT FROM AUTHOR]

The world demand for fuel as energy sources have arisen the need for generating alternatives such as biofuel. Biodiesel is a renewable fuel used particularly in diesel engines. Currently, biodiesel is mainly produced through transesterification reactions catalyzed by chemical catalysts, which produces higher fatty acid alkyl esters in shorter reaction time. Although extensive investigations on enzymatic transesterification by downstream processing were carried out, enzymatic transesterification has yet to be used in scale-up since commercial lipases are chiefly limited to the cost as well as long reaction time. While numerous lipases were studied and proven to have the high catalytic capacity, still enzymatic reaction requires more investigation. To fill this gap, finding optimal conditions for the reaction such as alcohol and oil choice, water content, reaction time and temperature through proper reaction modelling and simulations as well as the appropriate design and use of reactors for large scale production are crucial issues that need to be accurately addressed. Furthermore, lipase concentration, alternative lipase resources through whole cell technology and genetic engineering, recent immobilizing materials including nanoparticles, and the capacity of enzyme to be reused are important criteria to be neatly investigated. The present work reviews the current biodiesel feedstock, catalysis, general and novel immobilizing materials, bioreactors for enzymatic transesterification, potential lipase resources, intensification technics, and process modelling for enzymatic transesterification. [ABSTRACT FROM AUTHOR]

Biodiesel production has grown rapidly in response to the escalating price of fossil fuels in the last 20 years. Biodiesels appear to be one of the solutions to fulfil the increasing energy demands of the transportation sector since it can be used as substitutes of diesel in diesel engines without the need to modify the engines. The aim of this study is to evaluate the properties of biodiesels produced from crude palm and Calophyllum inophyllum oils using a pilot plant. A 50 L stainless steel jacketed reactor pilot plant is built to convert crude palm oil into palm methyl ester using transesterification process whereas crude C. inophyllum oil is processed using acid-catalysed esterification followed by alkaline-catalysed transesterification. The properties of the palm and C. inophyllum methyl esters are characterized according to the American society for testing and materials (ASTM) D6751 and European standard (EN) 14214 standards. In a latter section of this study, the palm and C. inophyllum methyl esters are blended with diesel fuel using different volume ratios. The oxidation stability of these blends is evaluated for two storage conditions for 90 days: (1) vacuum chamber and (2) room temperature. The oxidation stability of these blends is maintained for more than 12 h for 90 days when the fuels are stored in the vacuum chamber, which fulfils the biodiesel standards. Based on the results, both crude palm and C. inophyllum oils are potential feedstocks for industrial-scale biodiesel production and the biodiesels can likely replace diesel fuel in the future. [ABSTRACT FROM AUTHOR]

Biodiesel from non-edible seeds has attracted the attention of the authors to investigate Hevea brasiliensis (HB) and Ricinus communis (RC) as potential feedstocks. Biodiesel production was carried out using esterification-neutralization-transesterification (ENT) process. The transesterification process was carried out under variation methanol to oil molar ratio, catalyst concentration, reaction temperature, reaction time and speed agitation. On top of that, optimization was evaluated using Response Surface Methodology (RSM) and a quadratic polynomial model for ENT method. The optimization results show that production biodiesel from HBME and RCME with ENT method were 99.32% and 99.07% respectively. All the properties measured for produced methyl ester met in ASTMD 6751. Moreover, the presence of ricinoleic (α-elaeostearic) in RCME can improve the cold point, pour point and cold filter plugging point, which resulted in −40.4 °C, −27.8 °C and −35.0 °C respectively. The results of the cold flow properties are better due to higher unsaturated fatty acid concentration. It is indicates that RCME has good performance during cold weather engine operation. It short, biodiesel production using ENT method can produce high methyl ester yield and good biodiesel properties. [ABSTRACT FROM AUTHOR]

• Process intensification with solid Jatropha seeds to produce high quality biodiesel. • High FAME purity (99.03%) was achieved in 15 min after transesterification. • Ultrasonication showed higher biodiesel purity and yield than conventional stirring. • High R2 values for FAME purity (0.9926) and biodiesel yield (0.9845) from ANN model. • The physicochemical properties of biodiesel fulfilled the ASTM and EN standards. A two-step catalytic reactive extraction and transesterification process was adopted to synthesize biodiesel from solid Jatropha seeds, a non-edible source with high free acid content, directly using ultrasound irradiation. From the intensification of reactive extraction process coupled with ultrasound, esterified oil with satisfactory extraction efficiency of 84.0 ± 0.5%, FAME purity of 38.6 ± 1.3% and esterification efficiency of 71.1 ± 1.3% were obtained. High acid value (AV) of 18.2 ± 0.5 mg KOH/g was successfully reduced to 5.3 ± 0.2 mg KOH/g. In the subsequent transesterification of esterified Jatropha oil, FAME purity of 99.0 ± 1.3% and biodiesel yield of 85.2 ± 1.3% were attained at KOH loading of 1.5 wt.%, methanol to oil molar ratio of 12:1 and ultrasonic amplitude of 60% after 15 min reaction time. From the artificial neural network (ANN) modelling, coefficient of determination (R2) for FAME purity and biodiesel yield were found to be 0.9926 and 0.9845, respectively, which proved that the model had good fit with the experimental data. Under the same optimized reaction conditions, this process intensification could achieve higher FAME purity (99.0% vs. 91.8%), biodiesel yield (85.2% vs. 75.6%) and AV reduction efficiency (88.5% vs. 88.2%) than conventional magnetic stirring. [ABSTRACT FROM AUTHOR]

The purpose of this study was the improvement of cold flow and lubricity characteristics of biodiesel produced from the palm-sesame oil blend. Extreme learning machine (ELM) and response surface methodology (RSM) techniques were used to model the production process and the input variables (time, catalyst amount, methanol to oil ratio, and duty cycle) were optimized using cuckoo search algorithm. The mean absolute percentage error (MAPE), coefficient of determination (R2), mean square error (MSE), root mean square error (RMSE), and standard error of prediction (SEP) were calculated to evaluate the performance of RSM and ELM. The results showed that ELM model had better performance in prediction than RSM model. The optimum yield of P50S50 biodiesel obtained was 96.6138% under operating parameters of time (38.96 min), duty cycle (59.52%), methanol to oil ratio (60 V/V %) and catalyst amount (0.70 wt%). The cold flow characteristics of P50S50 biodiesel are significantly improved like cloud point (7.89 °C), pour point (3.80 °C), and cold filter plugging point (- 1.77 °C) with better oxidation stability 6.89 h. The average coefficient of friction P50S50 biodiesel was lower than palm biodiesel (B100) and B10 commercial diesel by 2.29% and 12.37% respectively. • Biodiesel was produced from Palm-sesame oil blend using ultrasound technique. • Cold flow and tribological characteristics of palm-sesame biodiesel were improved. • The process variables were optimized by RSM and ELM with cuckoo search algorithm. • ELM-CS model predicted better than RSM based on Box Behnken Design. [ABSTRACT FROM AUTHOR]

This study evaluated the utilisation of biomass wastes as catalyst supports by comparing the catalytic performance of papaya seed, empty fruit bunch (EFB) and corncob biomass waste derived carbon based acid catalysts applied for biodiesel production through esterification reaction of palm fatty acid distillate (PFAD) and methanol. Arylation of 4-benzenediazonium sulfonate synthesis method was able to sulfonate the catalyst support efficiently. The activated carbon (AC) synthesised possessed high porosity with surface area ranged between 639.68 and 972.66 m2/g. The effect of catalyst synthesising condition including carbonisation temperature (600–1000 °C), sulfonation time (0.5–2.5 h) and sulfanilic acid to AC weight ratio (3:1–13:1) towards the FAME yield and free fatty acid (FFA) conversion were evaluated. At the optimum catalyst synthesis conditions, corncob waste derived sulfonated AC catalyst exhibited the highest FAME yield and FFA conversion of 72.09% and 93.49%, respectively. Reusability study showed that corncob waste derived sulfonated AC catalyst was able to achieve relatively high FAME yield at the first two reaction cycles. The esterification reaction followed the irreversible pseudo-homogeneous reaction model. The high catalytic efficiency of the catalyst had shown its high potential to fit into the cost-effective and sustainable framework for biodiesel production. Image 1 • Utilisation of various biomass waste as catalyst support for biodiesel production. • 4-BDS sulfonation method was efficient for esterification reaction. • Sulfonated catalyst derived from corncob exhibited high catalytic performance. • Biodiesel yield and FFA conversion were obtained at 72.09% and 93.49%, respectively. • The reaction obeyed irreversible pseudo-homogeneous reaction model. [ABSTRACT FROM AUTHOR]

Biodiesel is gaining attention as a remedy for the increasing demand of fossil fuels which is depleting rapidly. Commercial homogeneous catalysts in the biodiesel production industry are facing challenges such as separation difficulties and severe corrosion which will lead to the increment of production and maintenance cost. Herein, this paper focuses on the comprehensive review of literature reported on the usage of biomass as the precursor for the catalyst used in biodiesel production. Compared to other commercial catalysts, the usage of biomass as catalyst precursor possesses several advantages such as abundantly available, cheaper raw materials, reusable, non-toxic and biodegradable. Carbon material synthesized from biomass which acts as the efficient support for active sites due to its high porosity and surface area characteristic has been studied widely. The latest development of biomass derived basic, acidic and magnetic heterogeneous catalyst through several state of the art synthesis pathways starting from the synthesis of the supporting material (carbon) until the functionalization process to form the complete catalyst was reviewed. Apart from direct sulfonation using sulfuric acid, sulfonation by reduction and arylation were less hazardous and provided comparable active sites activity. Most biomass based catalysts exhibited good catalytic performance by providing high biodiesel yield of above 80% at optimum conditions. Besides that, various kinetic models developed from the reaction kinetic study catalyzed by biomass based catalyst were also reviewed as a preparatory stage for the scaled-up commercialization process of the studied catalyst in the biodiesel production sector. This catalyst could assist to lower the activation energy required for the reactions and thus enables higher reaction rate to reach equilibrium. Continuous research on producing high performing biomass based catalyst with minimum resources is needed in order to achieve the ultimate goal of green and sustainable biodiesel industry. [ABSTRACT FROM AUTHOR]

In this study, kernel-based extreme learning machine (K-ELM) and artificial neural network (ANN) models were developed in order to predict the conditions of an alkaline-catalysed transesterification process. The reliability of these models was assessed and compared based on the coefficient of determination (R 2 ), root mean squared error (RSME), mean average percent error (MAPE) and relative percent deviation (RPD). The K-ELM model had higher R 2 (0.991) and lower RSME, MAPE and RPD (0.688, 0.388 and 0.380) compared to the ANN model (0.984, 0.913, 0.640 and 0.634). Based on these results, the K-ELM model is a more reliable prediction model and it was integrated with ant colony optimization (ACO) in order to achieve the highest Ceiba pentandra methyl ester yield. The optimum molar ratio of methanol to oil, KOH catalyst weight, reaction temperature, reaction time and agitation speed predicted by the K-ELM model integrated with ACO was 10:1, 1 %wt, 60 °C, 108 min and 1100 rpm, respectively. The Ceiba pentandra methyl ester yield attained under these optimum conditions was 99.80%. This novel integrated model provides insight on the effect of parameters investigated on the methyl ester yield, which may be useful for industries involved in biodiesel production. [ABSTRACT FROM AUTHOR]

Owning to the presence of essential mineral nutrient content in wastewater, cultivation of microalgae using wastewater sources provides an alternative and sustainable solution for biodiesel production. Hence, the potential of using domestic wastewater as nutrient source to cultivate Chlorella vulgaris was presently studied. It was found that the microalgae was favoured to grow in domestic wastewater under the conditions of 0.02 v/v of wastewater, initial pH of 3, and 0.03 v/v of initial amount of microalgae seed with 24 h of continuous illumination. Under these conditions, a high lipid content of 32.7% was embedded within the microalgae biomass. From the analysis of fatty acid methyl ester (FAME) profile, the extracted microalgae lipid was suitable for biodiesel production. The existing growth kinetic models were able to predict the growth of Chlorella vulgaris using the domestic wastewater as nutrients source. The fair model fitting was however limited to contaminant-free conditions, where the growth decays of the microalgae was negligible. [ABSTRACT FROM AUTHOR]

The non-edible oil from Schleichera oleosa possesses the potential as a feedstock for biodiesel production. In this study, the biodiesel production was performed using two-step transesterification process on a laboratory scale. The parameters studied were reaction temperature, molar ratio of methanol to oil, catalyst concentration, reaction time and catalysts type. An analysis of variance (ANOVA) was used to determine the methyl ester yield. The optimum conditions were obtained as follows: reaction temperature at 55 °C, methanol to oil molar ratio of 8:1, 1 wt.% of hydroxide catalyst (KOH and NaOH) and 1 wt.% methoxide catalyst (CH 3 OK and CH 3 ONa) for reaction time 90 min. Based from these optimum conditions, the observed ester yields from different catalysts were average 96%, 93%, 91% and 88% for KOH, NaOH, CH 3 OK and CH 3 ONa respectively as the catalyst. S. oleosa methyl ester (SOME) exhibited a satisfying oxidative stability of 7.23 h and high cetane number (50.6) compared to petrol diesel (49.7). Besides, SOME has good pour and cloud point of −3.0 °C and −1.0 °C respectively due to high unsaturated fatty chain. As a conclusion, this study reveals that biodiesel production from SOME, as one of non-edible feedstock, is able to be an alternative for petrol diesel. Moreover, the produced biodiesel from SOME could be used in diesel engine without major modification due to its properties and can be used in cold regions. [ABSTRACT FROM AUTHOR]

Current world energy usage is trying to gradually shift away from fossil fuels due to the concerns for the climate change and environmental pollutions. Liquid energy from renewable biomass is widely regarded as one of the greener alternatives to partially fulfil the ever-growing energy demand. Contemporary research and technology has been focussing on transforming these bio-resources into efficient liquid and gaseous fuels which are compatible with existing petrochemical energy infrastructure. Due to the wide range of properties and compositions from different types of biomass, there are ample of processing routes available to cater for different demands and requirements. In addition, they can produce multi-component products which can be further upgraded into higher value products. This conceives the idea of bio-refinery where different biomass conversion processes are incorporated and proceed simultaneously at one location. However, the underlying complexity in integrating different processes with varying process conditions will undoubtly incurs prohibitive cost. Consequently, process intensification plays an important role in minimizing both the capital and operating costs associated with process integration in bio-refineries. Recently, process intensification for biodiesel production has been developing rigorously due to increasing demand for cost-cutting measures. Supercritical fluid process allows biodiesel production to be performed without any addition of catalyst. Meanwhile, catalytic in situ or reactive extraction process for biodiesel production successfully combines the extraction and reaction phase together in a single processing unit. In this review, the important characteristics and recent progress on both of the intensification processes for biodiesel production will be critically analyzed. The prospects and recent advances of supercritical reactive extraction (SRE) process which integrates both of the processes will also be discussed. This review will also scrutinize on the methods for these processes to compliment future bio-refinery setup and more efficient utilizing of all of the products generated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ceiba pentandra biodiesel was prepared by two-step transesterification. [•] The main FAC of C. pentandra is 18.54% of malvalic acid. [•] Engine performance and emission are conducted for CPME and its blends. [•] The CPB10 gives the best engine performance at 1900rpm. [•] The CO, HC and smoke opacity were lower for all biodiesel blends. [ABSTRACT FROM AUTHOR]