Ester Yield Research Articles

A novel in situ transesterification of yellow horn seeds to biodiesel using a dual function switchable solvent

A novel and cyclic in situ transesterification of yellow horn (Xanthoceras sorbifolia Bunge.) seeds to biodiesel using the switchable solvent, N, N-dimethylcyclohexylamine (DMCHA) as both a reusable solvent and catalyst was proposed. An optimizing study for the reaction conditions has been performed through response surface methodology. The maximum yield of fatty acid methyl esters (FAMEs) achieved 96.07% under the best conditions of temperature 63.93 °C, 28.05 min, methanol amount of 10.41 mL/g (v/w of material) and DMCHA amount of 16.42 mL/g. Notably, The results of mechanism study combined with molecular dynamics and quantum chemistry theory showed that DMCHA is compatible with the triglycerides, and the effect of the hydrogen bonds, interaction energy, and radial distribution function on DMCHA performance were investigated for the first time. This new configuration of using switchable solvent for simultaneous extraction and reaction would be an appropriate, efficient and environment-friendly approach for simplify biodiesel production.

Integrating life cycle assessment and characterisation techniques: A case study of biodiesel production utilising waste Prunus Armeniaca seeds (PAS) and a novel catalyst

Prunus Armeniaca seed (PAS) oil was utilised as a waste biomass feedstock for biodiesel production via a novel catalytic system (SrO–La2O3) based on different stoichiometric ratios. The catalysts have been characterised and followed by a parametric analysis to optimise catalyst results. The catalyst with a stoichiometric ratio of Sr: La-8 (Sr–La–C) using parametric analysis showed an optimum yield of methyl esters is 97.28% at 65 °C, reaction time 75 min, catalyst loading 3 wt% and methanol to oil molar ratio of 9. The optimum catalyst was tested using various oil feedstocks such as waste cooking oil, sunflower oil, PAS oil, date seed oil and animal fat. The life cycle assessment was performed to evaluate the environmental impacts of biodiesel production utilising waste PAS, considering 1000 kg of biodiesel produced as 1 functional unit. The recorded results showed the cumulative abiotic depletion of fossil resources over the entire biodiesel production process as 22,920 MJ, global warming potential as 1150 kg CO2 equivalent, acidification potential as 4.89 kg SO2 equivalent and eutrophication potential as 0.2 kg PO43− equivalent for 1 tonne (1000 kg) of biodiesel produced. Furthermore, the energy ratio (measured as output energy divided by input energy) for the entire production process was 1.97. These results demonstrated that biodiesel obtained from the valorisation of waste PAS provides a suitable alternative to fossil fuels.

Comparison of Ex-Situ and In-Situ Transesterification for the Production of Microbial Biodiesel

Microbial biodiesel is converted from microbial lipids via transesterification process. Most microbial biodiesel studies are focusing on the use of microalgal lipids as feedstock. Apart from using microalgae for lipid biosynthesis, lipids can also be extracted from other oleaginous microorganisms like fungi and yeast. However, there are gaps in the studies of lipid production from filamentous fungi, especially in-situ transesterification process. The aim of this project is to compare in-situ with the ex-situ transesterification of fungal biomass from Aspergillus oryzae. In ex-situ transesterification, two methods of lipid extraction, the Soxhlet extraction and the Bligh and Dyer extraction, were performed. For in-situ transesterification, two methods using different catalysts were investigated. Base-catalyzed in-situ transesterification of fungal biomass resulted on the highest Fatty Acid Methyl Esters (FAME) yield. The base-catalyzed in-situ transesterification was further optimized via Central Composite Design (CCD) of Response Surface Methodology (RSM). The parameters investigated were the catalyst loading, methanol to biomass ratio and reaction time. The optimization showed that the highest FAME yield was at 25.1% (w/w) with 10 minutes reaction time, 5% catalyst and 360:1 of the ratio of the methanol to biomass. Based on Analysis of Variance (ANOVA), the model was found to be significant according to the value of “Prob >F” of 0.0028. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A pronounce approach on the catalytic performance of mesoporous natural silica toward esterification of acetic acid with iso‐amyl, benzyl, and cinnamyl alcohols

AbstractCatalytic esterification of acetic acid with iso‐amyl, benzyl, and cinnamyl alcohols in the liquid phase over unmodified natural silica catalyst has been studied. The virgin and calcined catalysts were characterized by thermal analyses (Thermogravimetry (TG) and diffrential thermal analysis (DTA)), X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and N2 sorption analyses. The acidity of natural silica catalysts was investigated using isopropyl alcohol dehydration and chemisorption of pyridine and dimethyl pyridine. The results indicated that most of the acidic sites are of Brϕnsted type and of intermediate strength. The effect of different parameters such as reaction time, molar ratio, catalyst dosage, and calcination temperature was studied. Natural silica catalyst exhibited excellent catalytic performance with a selectivity of 100% to acetate esters formation. The maximum yields of isoamyl, benzyl, and cinnamyl acetate esters obtained in the batch conditions were 80, 81, and 83%, respectively. Whereas on adopting a simple distillation technique, these yields were successfully improved to higher values of 97, 98, and 90%, respectively. Experimental results manifested that the reaction followed Langmuir–Hinshelwood mechanism. Finally, the catalyst could be completely recycled without loss of its activity after four cycles of the esterification reactions.

Enhanced biodiesel production from wet microalgae biomass optimized via response surface methodology and artificial neural network

This study investigates modeling and optimal conditions for biodiesel production from exceedingly wet microalgae Chlorella pyrenoidosa using the catalyst, hydrochloric acid. Three levels of Box-Behnken design response surface methodology were used to optimize individual and interactive effects of parameter time (120–240 min), temperature (120–160 °C), solvent-to-wet biomass ratio (2.0–4.67), and hydrochloric acid concentration (2–4 M). Temperature was the most significant factor for direct transesterification of wet microalgae (low p-value (0.0001) and high F-value (53.89). The highest yield (19.90%) of fatty acid methyl ester was obtained on dry biomass weight basis under the optimum conditions of 240 min, 146 °C, 2.83 (vol/wt), and 3.86 M acid concentration. The artificial neural network and response surface methodology were trained with Box-Behnken design data to predict responses, and to develop and compare each model's predictive abilities. The accuracy of results indicates that both models predict the experimental data for fatty acid methyl ester yields with high correlation coefficients (R2) 0.94 and 0.92, respectively for artificial neural network and response surface methodology. The potential for producing biodiesel from C. pyrenoidosa is validated by the high yields of C18 fatty acid methyl esters. Experimental analysis demonstrated biodiesel quality in comparison with European and US standards.

Performance of Liquid Eversa on Fatty Acid Ethyl Esters Production by Simultaneous Esterification/Transesterification of Low-to-High Acidity Feedstocks

Liquid Eversa was evaluated in hydrolysis of acylglycerols from soybean oil deodorizer distillate (SODD), as well as simultaneous esterification/transesterification of SODD with low-to-high free fatty acids (FFAs) content using ethanol as acyl acceptor. Hydrolysis of SODD at mild temperature (37 °C) and without pH control (water:SODD mass ratio of 4:1) increased its FFAs content from 17.2 wt.% to 72.5 wt.% after 48 h reaction. A cold saponification of SODD allowed a saponification phase (SODD-SP) to be recovered with 93 wt.% saponification index and 2.25 wt.% FFAs content, which was used to find the experimental conditions for simultaneous esterification/transesterification reactions by experimental design. Temperature of 35 °C, enzyme concentration of 8.36 wt.%, and molar ratio of 3.64:1 (ethanol:SODD-SP) were found as the best conditions for fatty acid ethyl esters (FAEEs) production from SODD-SP (86.56 wt.% ester yield after 23 h reaction). Under the same reaction conditions, crude SODD (17.2 wt.% FFAs) and hydrolyzed SODD (72.5 wt.% FFAs) yielded products containing around 80 wt.% FAEEs. Caustic treatment could increase the ester content to around 90 wt.% and reduce the FFAs content to less than 1 wt.%. Our results show the good performance of liquid Eversa in aqueous (hydrolysis reactions) and organic (esterification/transesterification reactions) media.

The influence of residue sodium ions in mixed oxide on catalytic activity in transesterification of vegetable oil

The Mg-Al mixed oxides are an attractive acid-base catalyst with various activity published even for the same reaction under similar conditions. The differences in the results can be caused by impurities remaining after synthesis, which is very often omitted in papers. The influence of remaining sodium impurities (from 5 to 345 μmol/g of hydrotalcite) on the catalysed transesterification of vegetable oil was studied. The novelty consists in the detailed description of the transformation of sodium species throughout synthesis of mixed oxides: the sodium nitrates, presented in hydrotalcites, were transformed to sodium oxide (during calcination), which reacted with water (present in oil and methanol) to sodium hydroxides. During transesterification, the sodium hydroxide leached to the liquid phase and so increased the ester yield as a homogeneous catalyst. The ester content was only 19 wt.% with the catalyst containing almost no sodium ions (5 μmol/g), but only 18 μmol/g caused increasing of ester content to 50 wt.%. Moreover, the sodium compounds rapidly increased the catalyst activity by changing the active sites. The reusability of the catalyst was caried out and the ester content decreased to only 22% after four cycles, because the sodium leached.

Comprehensive Comparison of Hetero-Homogeneous Catalysts for Fatty Acid Methyl Ester Production from Non-Edible Jatropha curcas Oil

The synthesis of biodiesel from Jatropha curcas by transesterification is kinetically controlled. It depends on the molar ratio, reaction time, and temperature, as well as the catalyst nature and quantity. The aim of this study was to explore the transesterification of low-cost, inedible J. curcas seed oil utilizing both homogenous (potassium hydroxide; KOH) and heterogenous (calcium oxide; CaO) catalysis. In this effort, two steps were used. First, free fatty acids in J. curcas oil were reduced from 12.4 to less than 1 wt.% with sulfuric acid-catalyzed pretreatment. Transesterification subsequently converted the oil to biodiesel. The yield of fatty acid methyl esters was optimized by varying the reaction time, catalyst load, and methanol-to-oil molar ratio. A maximum yield of 96% was obtained from CaO nanoparticles at a reaction time of 5.5 h with 4 wt.% of the catalyst and an 18:1 methanol-to-oil molar ratio. The optimum conditions for KOH were a molar ratio of methanol to oil of 9:1, 5 wt.% of the catalyst, and a reaction time of 3.5 h, and this returned a yield of 92%. The fuel properties of the optimized biodiesel were within the limits specified in ASTM D6751, the American biodiesel standard. In addition, the 5% blends in petroleum diesel were within the ranges prescribed in ASTM D975, the American diesel fuel standard.

Catalytic Methods for the Production of Sugar Esters

Nowadays, Sugar esters (SEs) have become the focus of researchers due to their biocompatibility and extensive industrial applications as surfactants. This trend provides new methods and opportunities for the development of green synthetic chemistry. Taking the above into consideration, a critical review presented in this work emphasized the efficiency of catalyzing the synthesis of SEs with minimal hazardous by-products. These catalytic media have been employed with various impacts involving chemical, biological, and other catalytic materials. Chemical methods have been reported to show limitations in terms of preparation and bio-compatibility. To solve these shortcomings, therefore, other technologies have been adopted; ionic liquids (eutectic solvents), chemo-enzymatic systems and chemo-enzymatic systems on a catalytic surface. The use of chemo-enzymatic systems on catalytic surfaces has proved to be suitable in solving biocompatibility and stability problems and correspondingly increasing the yield of esters formed. Therefore, finding an improved catalytic surface, and the sustainable optimal reaction conditions for enzymes will be vital to improving sugar ester conversion. This study highlights the different catalytic advances employed in the esterification of SEs.

Characterization of Eggshell: A Heterogeneous Catalyst in Transesterification of Sand Apple (Parinari polyandra) Seed Oil


 
 
 The objective of this study was to characterize a low cost heterogeneous catalyst from the transesterification of sand apple (Parinari polyandra B.) biodiesel. Sand apple fruits were processed and oil was extracted using solvent extraction method. Raw eggshells were calcined at 800°C for 120 min in the muffle furnace. Surface properties of the raw and calcined eggshell were characterized using Fourier Transformed Infrared Radiation (FTIR) and X-Ray Fluorescence (XRF). Transesterification of the Sand Apple Oil (SASO) with ethanol in the presence of the calcined catalyst to produce ethyl ester and glycerol were optimized using Central Composite Design at different temperatures and time. Reactants for the transesterification process were the raw SASO and anhydrous ethanol. The study shows that raw eggshell was more stable with hydrogen bond form at 2,724 cm-1an while oil yield of 53.13 % was obtained from sand apple kernels. Ethyl ester yield of 90% was obtained from SASO. The results of transesterification shows the maximum biodiesel yield of 90% was obtained at reaction temperature of 65°C and time of 120 min, while the minimum yield of 70% was obtained at temperature of 55°C and time of 60 min; indicating that biodiesel increase with increase in time. Similarly, yield of ethyl ester of SASO also increased when the reaction temperature increased. The percentages of biodiesel yield obtained from SASO transesterification in this study showed that sand apple is promising oil for biodiesel production as compared with other vegetable oil crop obtained in previous studies
 
 

Metal-organic framework-derived Mg-Zn hybrid nanocatalyst for biodiesel production

Controlled synthesis of metal–organic framework (MOF)-derived Mg-Zn hybrid nanostructure was demonstrated for the development of basic catalysts applied in biodiesel production from soybean oil. Two types of Mg-Zn hybrid nanostructures were successfully fabricated under different atmospheres (Ar, air), (1) MgO nanoparticles encapsulated in Zn-based MOF (MgO@Zn-MOF) and (2) MgO nanoparticles uniformly decorated on ZnO nanoparticles derived from Zn-MOF (MgO@ZnO), respectively. Ultrafine MgO nanoparticles (<5 nm for MgO@Zn-MOF and ≈10 nm for MgO@ZnO) were successfully synthesized and homogeneously dispersed in the MOF-derived Mg-Zn hybrid nanostructures. Significant increases in the specific surface area (i.e., a maximum of 1048.5 m2/g) and corresponding basicity (i.e., by a maximum of 2.1 times) were achievable by using MOF-based strategy comparing to the Mg-Zn catalyst prepared by a conventional solution-based approach. High 3-cycle stability and high yields of fatty acid methyl esters at a stoichiometric feed ratio 3 were both achievable, 67.6% and 73.3%, by using MgO@Zn-MOF and MgO@ZnO as the catalysts, respectively. The work demonstrates a prototype study of utilizing MOF to develop high-performance basic nanocatalysts through fundamental understanding of material synthesis by design versus their corresponding activities.

Transesterification of Refined Sunflower Oil to Biodiesel Using a CaO/ZSM‐5 Powder Catalyst

AbstractThe production of biodiesel from refined sunflower vegetable oil over basic CaO/ZSM‐5 catalysts was investigated. Several catalysts with various loadings of CaO on ZSM‐5 were prepared, calcined at 800 °C, and characterized by N2 adsorption‐desorption, X‐ray diffraction, Fourier transform infrared spectroscopy, and CO2‐temperature‐programmed desorption techniques. Calcined catalysts were tested in the transesterification reaction and reaction conditions were optimized by varying the catalyst‐to‐oil ratio and reaction time. The most active catalyst was the CaO/ZSM‐5 catalyst with a 35 wt % loading which gave the highest fatty acid methyl ester yield. The high catalytic activity was attributed to the active basic sites generated following CaO addition. Furthermore, the catalyst demonstrated stability against the leaching process.

Designing an efficient and recoverable magnetic nanocatalyst based on Ca, Fe and pectin for biodiesel production

Magnetic catalysts containing Fe and Ca synthesized in the presence of pectin have demonstrated to be highly efficient in the transesterification reaction for biodiesel production. Catalysts were prepared by the co-precipitation method under a N2 atmosphere with Na2CO3 from a mixture of FeSO4, FeCl3, Ca(NO3)2, and pectin followed by calcination at 550 ˚C/6h. The influence of the Fe:Ca molar ratio in the catalytic activity on the transesterification reaction with methanol was evaluated in the presence or absence of pectin. The most efficient catalyst was prepared in the presence of pectin with a Fe:Ca molar ratio of 4.5:2 (FCP2), and the best experimental conditions were at 3 % wt catalyst, 14:1 of methanol: soybean oil molar ration and 7.5 h of reaction time, which resulted in a methyl ester yield of 96.3%. It was shown that the presence of the biopolymer in the synthesis enhances the catalytic activity of the material from 20% to 99% of biodiesel production. All materials were fully characterized by TEM, FTIR, TGA, BET, XRD and DC magnetometry. It was found that catalysts present high surface areas with a nanometer size (∼20 nm), giving rise to a superparamagnetic state with a magnetic saturation high enough for separation by means of a magnet. In contrast, catalysts prepared in the absence of pectin demonstrated poor performance in the transesterification reaction of biodiesel in the optimized experimental conditions. The magnetic properties and the biopolymer role are discussed.

Production of sustainable two-stroke engine biolubricant ester base oil from palm fatty acid distillate

In this study, palm fatty acid distillate (PFAD) was selected as the feedstock for biolubricant base oil production in two-stroke engine oils’ formulation. PFAD is a low-cost palm refinery by-product with a high free fatty acid (FFA) content (85%). The esterification of PFAD with neopentyl glycol (NPG) was conducted in the presence of a solid acid catalyst (SO42-/Fe2O3/Al2O3) to produce PFAD-NPG ester. Optimization profile indicated that PFAD conversion and PFAD-NPG ester yield were 84% and 82%, respectively, under optimum reaction conditions of 180 °C, 4 h, 2.0 wt% SO42-/Fe2O3/Al2O3 catalyst loading and a 2:1 PFAD to NPG molar ratio. The physicochemical properties of the base oil successfully comply with the Japanese Automotive Standards Organization (JASO) M345:2018 requirements for two-stroke oils in terms of sulfated ash content, kinematic viscosity at 100 °C and flash point. In addition, reusability of solid acid catalyst, SO42-/Fe2O3/Al2O3 was investigated, where PFAD conversion and PFAD-NPG ester yield were found to be excellent at 81% and 80%, respectively, which showed that the catalyst had good consistency after 5 cycles.

Transesterification of palm kernel oil with ethanol catalyzed by a combination of immobilized lipases with different specificities in continuous two-stage packed-bed reactor

Technically and economically viable production processes are frequently reported, but products often fail to meet EN 14214 specifications. This study aimed to investigate the transesterification of palm kernel oil catalyzed by a combination of lipases from different sources and produce biodiesel in accordance with current quality standards. Transesterification reactions were first carried out in a stirred batch reactor at 45 °C using an oil:alcohol molar ratio of 1:8. In batch runs, a 50:50 mixture of Burkholderia cepacia lipase and Thermomyces lanuginosus lipase immobilized onto a silica hydroxyethylcellulose matrix resulted in the highest fatty acid ethyl ester yield (98%) and a decrease in kinematic viscosity from 30.35 to 4.00 mm2 s−1. The product had undetectable levels of DAG and low content of MAG (1.68 wt%). The enzymes were then packed separately in a continuous two-stage reactor operating at different space times (16 and 14 h) and oil/alcohol molar ratios (1:12, 1:10, and 1:8). The highest volumetric productivity (415.3 μmol gcat−1 h−1) was achieved using an oil/alcohol molar ratio of 1:8 and space–time of 16 h. The biodiesel had an alkyl ester content above 98%, a MAG content of less than 0.7 wt%, undetectable DAG content, and kinematic viscosity of 4.22 ± 0.25 mm2 s−1, thereby complying with EN 14214.

Immobilization of porcine pancreatic lipase on activated carbon by adsorption and covalent bonding and its application in the synthesis of butyl butyrate

Porcine pancreatic lipase (PPL) extract have been immobilized on activated carbon (ACT) and functionalized activated carbon (FCT). The effects of immobilization solution pH, addition of surfactant Triton X-100, and pH and temperature in the catalytic properties of the biocatalyst were evaluated. The functionalization led to an increase in the point of zero charge (5.13–6.11), reduction in the oxygenated groups (2.15 meq.g−1 to 1.99 meq.g−1) and a specific surface area (1028 m2. g−1 to 132 m2. g−1). The optimum immobilization pH was 5.0, resulting in the PPL extract loading of 71.80 mg/g (ACT) and 55.2 mg/g (FCT). A better hydrolytic activity (239.6 U/g) was observed for ACT to 0.6 mM Triton-X concentration, while FCT exhibited higher activity (208.63 U/g) in the absence of surfactant. For the PPL extract immobilized on ACT, the activity at pH 8.0 was 240.95 U/g, while a greater activity was observed at pH 7.0 for the PPL extract immobilized on FCT (221.94 U/g). The temperature of 35 °C led the highest activity values. The esterification yield of butyl butyrate was 82 % and 66 % for the PPL extract immobilized on ACT and FCT, respectively. Both biocatalysts showed residual esterification yield greater than 86 % after five cycles of use.

Investigation of sulfonated solid acid catalysts derived from oil palm kernel shell, corncob, and diatomaceous earth for esterification of ethanol and propanoic acid, characterisation and their performance

In this study, solid acid catalysts were prepared from different sources including oil palm kernel shell, corncob, and diatomaceous earth. Then, the raw materials were sulfonated and further activated by a microwave-induced reactor. Characteristics of sulfonated oil palm kernel shell (OPS-AC), corncob (CK-AC), and diatomaceous earth (DE-AC) were analysed using FTIR, XPS, NH3-TPD, XRD, SEM, BET, and TGA to establish their physical and chemical properties. The CK-AC and DE-AC showed high potential to be used as solid acid catalysts consisting of the strong acid site (-SO3H and -COOH) with 2344 and 3098 μmol/g for CK-AC and DE-AC, respectively. The DE-AC exhibited better thermal stability by only 7% of mass loss observed. The ester yields of 54.2 and 60.4% were achieved over CK-AC and DE-AC, respectively. Moreover, DE-AC shows the outstanding reusability for five successive times, which is promising as the potential solid catalysts for ethyl propanoate production.

Development of Microwave-Assisted Sulfonated Glucose Catalyst for Biodiesel Production from Palm Fatty Acid Distillate (PFAD)

Microwave-heating method for catalyst preparation has been utilized recently due to its shorter operation time compared to the conventional method. Glucose, a renewable carbon source can be partially carbonized and sulfonated via microwave heating which could result in highly potential heterogeneous carbon-based acid catalyst. In this study, the impacts of the carbonization and sulfonation parameters during the catalyst preparation were investigated. Catalysts prepared were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), Brunauer-Emmet-Teller (BET), and Temperature Programmed Desorption–Ammonia (TPD-NH3). Analysis of the carbonization screening process discovered that the best incomplete carbonized glucose (ICG) prepared was at 20 minutes, 20 g of D(+)-glucose with medium microwave power level (400W) which exhibited the highest percentage yield (91.41%) of fatty acid methyl ester (FAME). The total surface area and acid site density obtained were 16.94 m2/g and 25.65 mmol/g, respectively. Regeneration test was further carried out and succeeded to achieve 6 cycles. The highest turnover frequency (TOF) of the sulfonated catalyst was methyl palmitate, 25.214´10−3 s−1 compared to other component of the methyl ester. Kinetic study was developed throughout the esterification process and activation energy from the forward and reverse reaction was 3.36 kJ/mol and 11.96 kJ/mol, respectively. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Statistical Optimisation using Taguchi Method for Transesterification of Reutealis Trisperma Oil to Biodiesel on CaO-ZnO Catalysts

Optimisation of biodiesel production from non-edible Reutealis Trisperma oil (RTO) was investigated using Taguchi method. Biodiesel was produced via consecutive esterification and transesterification reactions. Esterification of RTO was carried out using acid catalyst to decrease the amount of free fatty acid from 2.24% to 0.09%. Subsequent transesterification of the treated oil with methanol over a series of CaO-ZnO catalysts was optimized based on the L9 Taguchi orthogonal approach. The optimization parameters are Ca/Zn ratio (0.25, 0.5, and 1), methanol/oil ratio (10, 20, and 30) and reaction time (0.5, 1, and 2 h). CaO-ZnO catalysts at variation of Ca/Zn ratios were prepared using co-precipitation method and characterized using XRD, SEM, TEM, and FTIR analysis. The amount of methyl ester yield was used as the response parameter in the S/N ratio analysis and Analysis of Variance (ANOVA). The optimum parameter for RTO transesterification to biodiesel was determined at Ca/Zn ratio of 1, methanol oil ratio of 30 and reaction time for 2 h. Transesterification under these optimized parameter generated 98% of biodiesel yield, inferring the validity of the statistical approach. Furthermore, ANOVA analysis also confirmed that all the parameters were significantly contributed at approximately equal percentage towards the amount of biodiesel. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Development of CaO supported on modified geopolymer catalyst for transesterification of soybean oil to biodiesel

Heterogeneous base catalysts, CaO supported on modified geopolymer (Geo), were developed and characterized as low-cost catalyst for biodiesel production from the transesterification of soybean oil. Geo was modified and synthesized by facile method, meta-kaolin and fumed silica were employed as sources of silica, alumina and, foaming agent (Al metal). The modified Geo was then compared to the conventional Geo without foaming agent (unfoamed-Geo). The catalysts, CaO with various loadings supported on Geo, were prepared by applying microwave radiation and subsequent calcination in air at 600 °C. The addition of Al metal during the synthesis of a geopolymer resulted in larger pore size. The results from CO2-TPD and XPS suggested that the calcium species dispersed with strong interactions in the aluminosilicate network of the geopolymer structure leading to strong basicity of the catalysts. The reactivity results showed that the fatty acid methyl ester (FAME) yield of 30%CaO/Geo was 93.12 ± 0.48%, larger amount than that of 30%CaO/unfoamed-Geo (70.87 ± 0.22%). Moreover, 30%CaO/Geo could be reused for at least 3 runs, suggesting a promising catalyst for cost-effective biodiesel production.