Summary
Biodiesel is one of the most widely used alternative fuels to reduce exhaust emissions and the use of conventional fossil fuels. It can be synthesized from a transesterification reaction from ...vegetable oils or animal fats in the presence of homogeneous or heterogeneous catalysts. Some drawbacks of using homogeneous catalysts increased attention to heterogeneous catalysts for biodiesel production. Recently, heterogeneous catalysts derived from biomass have risen to the forefront of biodiesel production due to their sustainability, economical and eco‐friendly nature. In addition, they are easily recovered and constitute an alternative to eliminate biomass residues. This review highlights several biomass sources used as precursors for the production of heterogeneous catalyst. Furthermore, methods for preparing heterogeneous catalysts, the reaction mechanisms, catalyst advantages and drawbacks, their performance in biodiesel production, as well as the methodologies developed for their effective recovery are discussed in detail. Among lignocellulosic biomass‐based precursors, the paper takes into account those based on biochar, ash, carbonaceous substrate, and seed oil cake. Those catalysts obtained by both preparation methods (calcination and activation) have good catalytic activity for waste cooking oil or neat oils. Biomass ash or biochar‐based catalysts are also promising routes in biodiesel synthesis, but significant reductions in catalyst load, reaction time, temperature, and methanol‐to‐oil ratio must be reached.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•A novel sulfamic acid modified UiO-66 MOF was used for the production of biodiesel.•Biodiesel yield of 94.4 ± 0.3 % was obtained using RSM optimized reaction parameters.•The catalyst possesses a ...total acidity of 1.4 mmolg−1.•The surface area of the catalyst was found to be 561.2 m2/g.•Reusability of the catalyst was investigated upto 5-successive cycles.
A novel sulfamic acid-modified UiO-66 metal–organic framework (UiO-66/SA) catalyst was synthesized in this work for the esterification of oleic acid to biodiesel. Oleic acid was used as a test substrate as it constitutes a major proportion of several biodiesel feedstocks like Jatropha curcas oil, karanja oil, and waste cooking oil. The catalyst was extensively characterized by XRD, TGA, FT-IR, BET, SEM, CHNS and XPS. The catalyst demonstrated a high acidity of 1.4 mmol g−1 evaluated by ammonia-temperature programmed desorption (NH3-TPD) analysis. Central composite design (CCD) approach of response surface methodology (RSM) was used to process the optimization of various parameters (RSM) where, a maximum biodiesel yield of 94.4 ± 0.3 % was obtained under the optimized reaction conditions of methanol to oil molar ratio of 21.9:1, catalyst loading of 7.6 wt%, reaction temperature of 85 °C, and reaction time of 1.8 h. The activation energy for the esterification reaction was found to be 41.56 kJ mol−1 and further, the thermodynamic study confirmed the endothermic nature of the reaction. Multiple regressions and analysis of variance (ANOVA)were used to fit the experimental data to a quadratic equation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Biofuels derived from algae can have lower impact on the environment and the food supply than biofuels produced from crops. The strain selection, cultivation method, culture conditions and the ...chemical composition strongly influences the production costs but also the engine's performance and the exhaust gas emissions. The scope of this paper is to make a critical review about the impact of the use of biofuels produced from (micro) algae to power diesel engines. There is a huge disparity in the amount of papers published for algae culture, oil extraction, and biodiesel production compared to reporting performance on diesel engines. This paper presents an analysis of the papers published in this specific field. Generally, a reduction of torque and power output is reported. A wide range of blends up to B50 but also pure biodiesel has been tested. The blend showing results closest to diesel fuel appears to be B20. Several pollutants can be reduced if biofuels from different strains are used but an increase in NOx is generally reported, associated to higher temperatures in the combustion chamber. The use of emulsions instead of blends or neat biodiesel reveals a promising alternative with important reductions of CO2 and NOx. However, the few reports for engine tests present some contradictions, or are lacking important information about the experiments. The assessment of biodiesel produced from algae or microalgae is a field hardly explored and until today some reference papers contain contradictory results or non-well studied behaviors as this survey demonstrates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We obtained models for estimation of cetane number of biodiesel. Twenty-four neural networks using two topologies were evaluated. The best neural network for predict the cetane number was selected. ...The best accuracy was obtained for the selected neural network.
Models for estimation of cetane number of biodiesel from their fatty acid methyl ester composition using multiple linear regression and artificial neural networks were obtained in this work. For the obtaining of models to predict the cetane number, an experimental data from literature reports that covers 48 and 15 biodiesels in the modeling-training step and validation step respectively were taken. Twenty-four neural networks using two topologies and different algorithms for the second training step were evaluated. The model obtained using multiple regression was compared with two other models from literature and it was able to predict cetane number with 89% of accuracy, observing one outlier. A model to predict cetane number using artificial neural network was obtained with better accuracy than 92% except one outlier. The best neural network to predict the cetane number was a backpropagation network (11:5:1) using the Levenberg–Marquardt algorithm for the second step of the networks training and showing R=0.9544 for the validation data.
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GEOZS, IJS, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this investigation, puffing and micro-explosion occurrence in emulsified fuels are studied. The emulsified fuels are formulated using a micro-channel emulsifier, a blend of rapeseed oil in diesel ...fuel as continuous phase, water as dispersed phase and Sorbitan Sesquioleate as surfactant. Several stable dispersed systems are obtained, classified as emulsions based on their optical appearance and dispersed droplet size. The dynamic viscosity measured as a function of shear rate indicated non-Newtonian behavior with a shear-thinning response for all emulsions. An increase of water percentage led to emulsified fuels with higher viscosity levels. Finally, puffing and micro-explosion occurrence was studied by placing emulsified fuel droplets on a heated plate leading to the Leidenfrost effect. The puffing occurrence is reported for all emulsified fuels tested. A sudden puffing is noted when the water ratio is increased. Conversely, the micro-explosion phenomenon only occurred in emulsions formulated without surfactant. However, an analysis conducted on a smaller emulsion droplet showed several ejected child droplets and micro-explosion. This fact denotes a strong relationship between the emulsion droplet size, water ratio and water droplet size with the occurrence of the puffing and micro-explosion phenomena.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Vegetable oils and animal fats represent promising alternatives to diesel engine fuel because they can be obtained from different feedstocks and renewable sources; also their properties are close to ...diesel fuel. The direct use of these biofuels as a diesel engine fuel can cause several problems in engine performance and emissions. In order to obtain a more engine-friendly fuel, it is necessary to change the biofuels’ properties for which different methods have been used. One of the possibilities is using emulsification techniques in order to obtain emulsified biofuels (emulsions or microemulsions); through this method it is possible to lower viscosity and improve the atomization. However, emulsification techniques applied to vegetable oils and animal fats have not been studied thoroughly. For this reason, this paper presents an overview on the formulation and characterization of the emulsified biofuels using vegetable oils and animal fats, as well as the main experimental results reported about its use as a diesel engine fuel in the scientific literature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The prediction of bio-oil yield from pyrolysis of lignocellulosic biomass is important for processes optimization, modeling, and installation's design. This work models the bio-oil of lignocellulosic ...biomass yield by Artificial Neural Networks (ANN), being the inputs: cellulose, hemicellulose, lignin, pyrolysis temperature, heating rate, N
2
flow rate, and particle size. A database was created with 34 biomass types, modeling with 329 samples, training with 80%, and validating with 20%. A previous stage of screening was carried out with 100% of data for choosing the algorithm of the second phase and the number of neurons in the hidden layer; the selection criteria were the mean absolute error (MAE) and the correlation coefficient. The best performance was for backpropagation/Levenberg-Marquardt with 7:13:1 as ANN architecture. All ANN with less than 1% of MAE were tested for validating and the weight's matrix of the best one is shown. The selected network with a correlation coefficient of 0.9739 and MAE of 1.7159% for validation, only had four outlier values between 5 and 6%, the remaining 62 samples with all 263 used in training, had less than 5% of difference compared to the experimental values, thus representing a very accurate model for predicting bio-oil yield.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The use of algal biomass as a renewable source of energy is potentially promising. The literature on biofuels derived from
Sargassum
is limited compared to other macroalgae. The unusual seaweed bloom ...of
Sargassum
from 2011 to date can be caused by the following factors: eutrophication of the sea, climate change, and other oceanographic patterns. The atypical invasion has had great ecological and economic effects in the affected regions. Traditionally,
Sargassum
has been recovered from coasts and beaches for use as fertilizer, but new markets need to be found to exploit the large volumes produced by the seaweed influx and mitigate its impact. The biochemical composition of
Sargassum
biomass defines it as a potential feedstock for biofuel production. However, the high moisture and ash content constitute the limitations for the development of some energy extraction methods. On the other hand, the costs associated with the removal of high volumes of accumulated
Sargassum
from coasts and beaches, transportation, cleaning, and storage are relatively high. Therefore, the production of biofuels from
Sargassum
seaweed is still a technical, economic, and energy challenge. This review proposes a multifactorial approach to the potential use of
Sargassum
biomass as feedstock for energy production, especially by thermochemical conversion (combustion, gasification, pyrolysis, and hydrothermal liquefaction). The survey analyses the chemical composition, biomass productivity and coastal impact, energy output, thermochemical conversion processes, techno-economic challenges, and future perspectives. In addition, a
Sargassum
biomass biorefinery approach with a circular bioeconomy approach is proposed.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Jatropha curcas produces several useful by-products. Nevertheless, the application of by-products in gasification and pyrolysis is not well studied. A comprehensive review of the state of arts of the ...use of Jatropha by-products in thermochemical processes focused on the technical characteristics of by-products and their use for self-energy requirements in agroindustry is in this paper developed. The survey is focused on husk, cake, and shell. The proximate, ultimate analysis, chemical composition, ash composition, and technologies used for thermal processes are analyzed. A disparity in the number of publications on gasification and pyrolysis is observed. The main application in gasification is for Jatropha husk as feed. A simulation of the gasification process for Jatropha husk is also in this paper shown, including the composition of the producer gas. Concerning pyrolysis, the reports are focused on the use of seed oil cake. By gasification of by-products up to 10% H
2
and 20% CO can be reached and 64% with up to 42 MJ/kg for bio-oil production. Most of the contributions are focused on bio-oil obtaining, due to the technical advantages it brings. Half of the studies were developed in low scale lab pyrolyzers. As is demonstrated, JC by-products contribute to a fully sustainable technology, not only about energy production but also in the production of heterogeneous catalyzers, sustainability, precursor of activated carbons and chemicals. Increase of bio-oil yields and its use in diesel engines are current research subjects. In this respect, bio-oil purification, chemical conversion, and optimal use in engines should be addressed.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
•Discussion of various issues with regard to formulation of emulsions containing FAD.•Stable emulsions were produced using FAD, diesel fuel and a mixture of surfactants.•The effect of emulsions on ...engine performance and exhaust emissions were studied.•Emulsions containing FAD and water lead to higher BSFC and delayed start of combustion.•Emulsions were found as an effective way to reduce the nitrogen oxides emissions.
In this contribution an experimental investigation concerning the effect of emulsified fuels based on fatty acid distillates (FAD) on a single cylinder diesel engine performance and exhaust emissions was investigated. The single cylinder diesel engine assessment was conducted under selected test conditions, fixing the engine speed and varying the load. Emulsified fuels were formulated using blends of fatty acid distillates in diesel fuel as continuous phase, as well as deionized water as dispersed phase and Nonyl phenol with 8mol of ethylene oxide as surfactant. Over these conditions the brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), ignition delay (ID), rate of heat release (ROHR), cumulative heat release, nitrogen oxides (NOx), carbon monoxide (CO) and unburned hydrocarbons (HC) were analyzed. The results indicate that the use of emulsified fuels produce increases in the specific fuel consumption and decreases in the brake thermal efficiency for emulsions compared to diesel fuel and a blend of 30% FAD in diesel. On the other hand, later starts of combustion and retarded ROHR for emulsified fuels compared to diesel fuel and a blend of 30% FAD in diesel were obtained. Further, lower NOx and higher HC and CO emissions for emulsified fuels were reported.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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