Conversion Of Soybean Oil Research Articles

Conversion of soybean oil under subcritical water conditions into liquid biofuels with low oxygen contents

Although the hydrotreatment of natural triglycerides is a well-established route for producing sustainable aviation fuel and renewable diesel, its high hydrogen consumption is a concern. The hydrothermolysis of natural triglycerides is considered a highly promising alternative route; however, the correlation between process parameters and fuel properties and detailed chemical structures of the produced fuel have not been established. Herein, we investigated the conversion of soybean oil to gasoline-, jet fuel- and diesel-fraction hydrocarbons with low oxygen contents. The properties of fuels produced under various reaction conditions were analyzed comprehensively using simulated distillation, total acid number (TAN), and elemental analysis. Under the optimized reaction conditions of 420 °C, 4.5 MPa, an oil-to-water ratio of 6:1, and reaction time of 10 min, 26 % gasoline-, 62 % jet fuel-, and 90 % diesel-range hydrocarbons with a low oxygen content of 5.1 %, low TAN of 0.04 mg KOH g−1, and high calorific value of 42.7 MJ kg−1 resulted. To elucidate the reaction mechanism, the liquid products produced from soybean oil were analyzed using comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry. In addition, based on the oleic acid conversion under varying hydrothermal conditions, we proposed deoxygenation, cracking, cyclization, and aromatization pathways. The findings of this study present possibilities for producing sustainable biofuels with low oxygen contents for the aviation industry.

In-situ co-immobilization of lipase, lipoxygenase and L-cysteine within a metal-amino acid framework for conversion of soybean oil into higher-value products

We propose a co-immobilized chemo-enzyme cascade system to mitigate random intermediate diffusion from the mixture of individual immobilized catalysts and achieve a one-pot reaction of multi-enzyme and reductant. Catalyzed by lipase and lipoxygenase, unsaturated lipid hydroperoxides (HPOs) were synthesized. 13(S)-hydroperoxy-9Z, 11E-octadecadienoic acid (13-HPODE), one compound of HPOs, was subsequently reduced to 13(S)-hydroxy-9Z, 11E-octadecadienoic acid (13-HODE) by cysteine. Upon the optimized conditions, 75.28 mg of 13-HPODE and 4.01 mg of 13-HODE were produced from per milliliter of oil. The co-immobilized catalysts exhibited improved yield compared to the mixture of individually immobilized catalysts. Moreover, it demonstrated satisfactory durability and recyclability, maintaining a relative HPOs yield of 78.5% after 5 cycles. This work has achieved the co-immobilization of lipase, lipoxygenase and the reductant cysteine for the first time, successfully applying it to the conversion of soybean oil into 13-HODE. It offers a technological platform for transforming various oils into high-value products.

Biodiesel Production Using a Banana Peel Extract-Mediated Highly Basic Heterogeneous Nanocatalyst

Greener methods for the production of nanoparticles (NPs) are highly investigated to minimize the harmfulness of chemical synthetic processes. In this study, CaO (calcium oxide) NPs were synthesized using extracts of banana (Musa acuminata) leaves. The precipitate of Ca(OH)2 (calcium hydroxide) obtained from the precursor Ca(NO3)2 (calcium nitrate) was calcined at 900 °C in a muffle furnace to form CaO. The catalytic activity of the prepared CaO was studied in transesterification of soybean oil. From the 1H-NMR analysis, a high soybean oil conversion of 98.0% was obtained under the optimum reaction conditions of 8 wt% of catalyst loading, 2 h reaction time, and a 15:1 methanol to oil molar ratio at 65 °C temperature. 1H-NMR, 13C-NMR, and FT-IR spectroscopic studies of the product proved the formation of biodiesel. The CaO nanocatalyst was characterized using XRD, SEM-EDS, TEM, FT-IR, XPS, and BET analyses. The average diameter of the catalyst was determined as 46.2 nm from TEM analyses. The catalyst can be used successfully even after five active reaction cycles without substantial loss in the activity of the catalyst.

Microwave-assisted biodiesel production using ZIF-8 MOF-derived nanocatalyst: A process optimization, kinetics, thermodynamics and life cycle cost analysis

In this study a novel, high surface area, and recyclable nano-size solid basic catalyst is developed for the first time from ZIF-8 MOF-derived CaO/ZnO for the high-yielding transesterification of soybean oil (SO) to biodiesel with methanol under microwave irradiation. The chemical composition, texture and morphology of the catalyst were comprehensively characterized by FT-IR, SEM-EDS, XRD, TGA, XPS and BET. In addition, 1H NMR analyses were performed to confirm the conversion of soybean oil to biodiesel, whereas, GC–MS spectrum provide information about the chemical composition of the produced biodiesel. Kinetic studies are performed for the optimized catalyst and it follows the pseudo-first-order reaction. Thermodynamic analyses show that the transesterification of soybean oil to biodiesel reaction is endothermic and not spontaneous. By using Response surface methodology (RSM), the optimization of parameters that affect the biodiesel yield is studied. The transformation of 1:20 soybean oil with methanol using CaO/ZnO catalyst (7 wt%) gives 97.4 % biodiesel yield for the transesterification at 90 °C for 50 min. The catalyst shows good reusability after 5 successive cycles demonstrating its industrial-scale applications. According to Life cycle cost analysis (LCCA) the estimated price of 1 kg of biodiesel produced in this work is merely $1.11 showing high commercial applicability.

Terminalia arjuna bark – A highly efficient renewable heterogeneous base catalyst for biodiesel production

In agreement with the necessity for green synthesis, the present study elevates the feasibility of exploiting Terminalia arjuna bark calcined ash (TABCA) - a highly functional renewable heterogeneous alkaline catalyst for the cost-effective synthesis of fuel-grade fatty acid methyl esters (FAME) by soybean oil (SO) transesterification under microwave irradiation. The mesoporous nature, significant surface area, and an extreme degree of basicity owing to the presence of CaO, MgO, K2O, SiO2, Na2O, and P2O5 effectively facilitate the SO conversion. Under the optimal conditions of 24:1 M ratio of methanol: SO, 8 wt % catalyst concentration, 80 °C temperature and time period of 60 min, microwave irradiation exhibits highest biodiesel yield (99.2 ± 0.6%) and improved selectivity (100%). Likewise, FAME content in the biodiesel was found to be 99.01% from 1H NMR. The produced SO biodiesel meets the ASTM D6751 and EN 14214 standard requirements, making it compatible in existing engines. In addition, the mesoporous TABCA catalyst showed high stability for five consecutive transesterification reactions which yielded 80 ± 0.8% biodiesel without additional treatments.

Polyacrylonitrile fiber with light-driven intelligent reversible and switchable wettability as an environmental benign solid base for biodiesel production

Vigorous advocacy for the promising strategy on biodiesel replacing petrodiesel can effectively alleviate the dual pressure of energy deficiency and environmental pollution. Nevertheless, the difficulty of lowering larger mass transfer resistance between two-phases of alcohol/oil is a stumbling block in the biodiesel production. Furthermore, the high catalytic efficiency of the most commonly used solid bases for biodiesel production is weakened due to the saponification reaction caused by fatty acids in feedstock. Addressing these two issues has emerged as a pressing concern for achieving efficient biodiesel production. Herein, a polyacrylonitrile fiber (PANF) with light-driven intelligent reversible and switchable wettability, i.e., PANF-NH2@RAFT@SPA&[AD][OH] featuring Brønsted-Lewis di-base sites and photoresponsiveness, was successfully fabricated through reversible addition fragmentation chain transfer strategy. Physicochemical properties of the resulting fibers were characterized by FT-IR, XRD, NMR, TGA, SEM, TEM, XPS, WCA, and UV–Vis. The effect of methanol-to-oil molar ratio, reaction temperature, reaction time and catalyst feed on biodiesel production was also investigated. Under optimal conditions, a maximum soybean oil conversion of 100% was achieved with a corresponding biodiesel yield of 98.97%, which is an exceptional and unprecedented result. These impressive results can be ascribed to the microenvironment facilitated by the novel intelligent amphiphilic PANF, which effectively enhances mass transfer in a biphasic medium phase of methanol/oil. The microenvironment could be rapidly changed via Vis-regulating PANF hydrophobicity, followed by observably promoting catalyst recovery and phase separation between resultant biodiesel and excess methanol. This catalyst shows no obvious changes in terms of the catalytic activity and selectivity after successive reuses of up to 10 cycles. The economic feasibility and negligible environmental impact of this methodology, coupled with its expediency and efficacy for conducting experiments at kilogram-scale quantities, render it highly compatible with large-scale industrial production of biodiesel.

Thermodynamic Modeling of Liquid-Liquid Equilibrium in Ternary Systems with Biodiesel and Isolated Ester (Methyl Palmitate)

Liquid-liquid equilibrium data were measured and analyzed for two ternary systems (biodiesel + methanol + glycerol and methyl palmitate + methanol + glycerol). Biodiesel, produced by the conventional chemical route at 60 °C for 60 min, using methanol and soybean oil at a molar rate of 10:1 and potassium hydroxide concentration (KOH) of 1 wt% exhibited thermal decomposition at temperatures between 100 and 250 ºC, reaching mass loss of approximately 98.8%, confirming soybean oil conversion into biodiesel by gas chromatography and thermogravimetry. Tie line composition quality was verified using Othmer-Tobias and Hand correlation equations. The distribution and selectivity coefficients were calculated for the immiscibility regions. The experimental tie line data exhibited good correlation in the UNIQUAC and NRTL thermodynamic models. The biodiesel system displayed deviations of 0.66 and 0.53% for the UNIQUAC and NRTL models, respectively. In addition, the methyl palmitate system showed a 1.23 and 0.48% deviation for the UNIQUAC and NRTL model, respectively. The individual behavior of the main biodiesel esters , based on the UNIQUAC model parameters, demonstrated that the type of fatty acid does not interfere in model correlation, likely due to the similarity between their composition and properties.

Biodiesel production by transesterification of waste cooking oil in the presence of graphitic carbon nitride supported molybdenum catalyst

Development of the active metal species with high utilization and accessibility of oil macromoleculars is one of the critical factors affecting heterogeneous metal-based catalysts for production of biodiesel. Here, we synthesized two-dimensional graphitic carbon nitride supported molybdenum (xMo/g-C3N4) catalysts for the facile transesterification of waste cooking soybean oil. Various characterization results of these catalysts show the crystal structure of g-C3N4 is not destroyed, however, Mo oxides phase, containing Mo6+ and Mo5+ state, is detected on the surface of the Mo/g-C3N4 with much Mo-loading, and the ratio of Mo6+/Mo5+ increases significantly with the increasing Mo loading. As expected, compared with the neat g-C3N4 catalyst, the g-C3N4 supported Mo catalyst exhibits a better catalytic performance; especially the 10%Mo/g-C3N4 catalyst has the optimal waste cooking soybean oil conversion of 71.1% and biodiesel selectivity of 99.5%. Furthermore, the experimental parameters and catalytic reusability for the transesterification reaction over 10%Mo/g-C3N4 catalyst are investigated. Moreover, the possible deactivation mechanism and regeneration method of as-prepared catalyst are also proposed. This work provides a valuable tactics for the production of clean and low-cost biodiesel from waste cooking soybean oil in the presence of efficient solid catalyst.

Optimization of biodiesel production via transesterification of soybean oil using α-MoO3 catalyst obtained by the combustion method

A catalyst based on MoO3 was synthesized by a simple and fast pilot-scale combustion reaction method and applied to the conversion of soybean oil to biodiesel via transesterification. For that, the statistical analysis of the catalyst amount and temperature, factors that influence the process, was evaluated by means of central composite design 22. MoO3 was characterized in terms of structure by X-ray diffraction (XRD), textural characterization Brunauer-Emmett-Teller (BET), density by helium pycnometry (DE), particle size analysis (DG) and acidity tests by temperature-programmed desorption of ammonia (NH3-TPD), chemical analysis by X-ray fluorescence (EDX), morphology by scanning electron microscopy (SEM) and catalytic properties. The transesterification products were characterized by gas chromatography (GC), acidity index (AI) and kinematic viscosity (KV). The results indicate the catalyst formation with a surface area of 1.36 m2g−1, and density of 4.5 g/cm3 which consists of a single crystalline phase of orthorhombic configuration, with total NH3 acidity of 33.61 μ.mol/g. Morphological characterization revealed that the catalyst is formed by irregular plates of various sizes and shapes, with a wide sizes range of agglomerated particles. In the soybean oil transesterification reactions, the catalyst was active showing 96.9% conversion to ethyl esters. The experimental design was meaningful and predictive, with a reliability level of 95%. The statistical analysis identified temperature as a significant variable for the adopted planning. To conclude, a new single-phase catalyst (α-MoO3) has been developed and successfully applied to the biodiesel Synthesis from soybean oil. These results have a positive and promising impact for biodiesel production by transesterification of soybean oil against ethanol.

Digging and identification of novel microorganisms from the soil environments with high methanol-tolerant lipase production for biodiesel preparation

Converting renewable biomass into carbon-neutral biofuels is one of the most effective strategies to achieve zero carbon emissions and contribute to environmental protection. Microorganisms from the soil were primarily screened on the rhodamine B-plate for highly-active lipase producing strains and re-screened on a tributyrin-methanol plate using crude lipases produced from the initially screened-out strains. The lipase-producing strains with higher methanol-tolerant lipase were identified based on morphological characteristics and 16S rDNA sequencing. The crude lipases with much higher methanol-tolerance from screened top-4 strains, Stenotrophomonas maltophilia D18, Lysinibacillus fusiformis B23, Acinetobacter junii C69, and A. pittii C95 showed temperature optima of 25 °C, 35 °C, 30 °C, and 30 °C at pH 7.0, respectively, while their pH optima were 8.0, 7.0, 7.5, and 7.5 at each optimum temperature, respectively. After 24-h incubation, they retained more than 85% of their original activities in 25%, 15%, 20%, and 20% of methanol, respectively. They catalyzed the conversion of soybean oil into biodiesel by yields of 63.1%, 35.4%, 74.6%, and 78.5% after 24-h reactions, respectively. In conclusion, the as-isolated microorganisms producing high methanol-tolerant lipase are considered promising to provide robust biocatalyst for efficient biodiesel preparation and other industrial applications.

Chemoselective decarboxylation of higher aliphatic esters to diesel-range alkanes over the NiCu/Al2O3 bifunctional catalyst under mild reaction conditions

An efficient and highly selective decarboxylation catalyst has been developed for the production of diesel-range alkanes from the conversion of higher aliphatic esters under mild reaction conditions. Using methyl stearate as a model substrate, the NiCu/Al2O3 bifunctional catalysts derived from layer double hydroxide (LDHs) precursors showed excellent catalytic performance with 100% conversion and 97.5% selectivity to heptadecane at 260 °C and 3.0 MPa H2. On the other hand, the catalytic performance of NiCu/Al2O3 catalyst was also tested in the conversion of soybean and waste cooking oils under the mild conditions. The results showed that a high yields of diesel-range alkanes (>80 wt%) were obtained from the conversion of soybean oil and waste cooking oil, respectively.Detailed characterization (XRD, H2-TPR, HRTEM, XPS, and NH3-TPD) indicates, after reduction at 500 °C in H2 atmosphere, the NiCu alloy phase is the predominant phase and the Ni, Cu, Al species exhibited homogeneous distribution in the NiCu/Al2O3 catalyst. The remarkable decarboxylation performance mainly results from the synergistic effect between the metal active sites of NiCu alloy and Lewis acid sites of support Al2O3. The Lewis acid sites (Al3+) of support serve as active sites for the activation of carbonyl group of higher aliphatic esters, while H2 dissociation and decarbonylation of intermediate fatty aldehyde are achieved on the NiCu alloy sites. Compared with the monometallic Ni/Al2O3 catalyst (183.8 kJ/mol), the introduction of Cu species in the bimetallic NiCu/Al2O3 catalyst greatly reduced the activation energy (138.1 kJ/mol) of fatty acid ester conversion via promoting the dispersion of Ni species, reducing the dissociation energy of hydrogen on Ni, and increasing the electron density of Ni, which results in high decarboxylation performance of NiCu/Al2O3 under mild reaction conditions.

Preparation of CaO/KIT-6 solid base catalyst and its catalytic performance in transesterification

CaO/KIT-6 was successfully prepared by loading activated calcium oxide particles on the surface of mesoporous silica (KIT-6) by post-synthesis method and tested for the transesterification of soybean oil with methanol. The catalyst was characterized by XRD, XPS, CO2-TPD, N2 adsorption-desorption and TEM. It was found that when the molar ratio of methanol to oil is 12, the reaction temperature is 65°C, the addition of catalyst is 8% and the Ca/Si atomic ratio is 0.4, the conversion of soybean oil exceeds 99.9% at 2 h. After 5 cycles, the catalytic activity decreases slightly and the conversion is still up to 90%. Compared with CaO and other supported catalysts, CaO/KIT-6 catalyst exhibits higher catalytic performance and good reusability at lower methanol-to-oil molar ratio.

Fabrication of hollow cage-like CaO catalyst for the enhanced biodiesel production via transesterification of soybean oil and methanol

Designing a cost-effective and environmentally-friendly heterogeneous catalyst for biodiesel production is an essential yet a challenging aspect for renewable energy applications. To achieve this, a newly fabricated hollow cage-like CaO catalyst (CaO-700N) was prepared by the pyrolysis of hollow CaCO3 under precisely controlled calcination temperature (700 °C) and N2 atmosphere. The prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature programmed desorption of CO2 and N2-adsorption/desorption. The newly fabricated CaO catalyst exhibited porous hollow cage-like structure, high basic strength and density, leading to high catalytic activity for the production of biodiesel via the transesterification of soybean oil with methanol. A biodiesel yield of 97.80 % was attained under the optimal reaction conditions of 3 wt% catalyst concentration, 15:1 methanol/oil molar ratio, 65 °C reaction temperature and reaction time of 2 h. The catalyst remained highly stable and maintained biodiesel yield of above 90.30 % after the fifth reuse. Based on the characterization and activity results, a suitable reaction mechanism for the catalytic conversion of soybean oil to biodiesel using hollow cage-like CaO catalyst was proposed. Moreover, the scaling up of transesterification with the synthetic biodiesel production of over 95.69 % for 4 h was reported. The physiochemical properties of synthetic biodiesel were in accord with the biodiesel standards. Attributed to the intriguing properties like cost-effectiveness, ease of synthesis and environmental greenness, the hollow cage-like CaO catalyst could be considered as a potential candidate for the production of biodiesel on industrial level application.

Two-step preparation of Keggin-PW12@UIO-66 composite showing high-activity and long-life conversion of soybean oil into biodiesel.

A polyoxometalate acid can be encapsulated into a metal–organic framework to construct a novel kind of solid-acid catalyst. In this work, the two-step method —high-temperature preparation of Zr6O4(OH)4(CH3COO)12 and low-temperature self-assembly—has been adopted to synthesize the PW12@UIO-66 composite (PW12 = H3PW12O40; UIO-66 = Zr6O4(OH)4(OOC–C6H4–COO)12). The as-synthesized PW12@UIO-66 composite exhibits highly crystalline, good octahedron morphology, large specific surface area (1960 m2 g−1) and high thermal stability (>500 °C), which clearly demonstrates the potential as a solid-acid catalyst. Additionally, the PW12@UIO-66 composite may be accomplished with 85% utilization of H3PW12O40 and 95% yield through this synthetic procedure. The performances of the PW12@UIO-66 composite are investigated by catalyzing the simultaneous transesterification and esterification of soybean oil into biodiesel. Under the optimal conditions, the conversion of the soybean oil into biodiesel would exceed 90% over the as-synthesized PW12@UIO-66 composite. As the crucial indexes for industrial prospects, the recycling and life experiments were surveyed. After 10 times recycling and 4 weeks, the structure and performance of the PW12@UIO-66 composite remained unchanged and in the meantime the PW12@UIO-66 composite still maintained a high activity to convert soybean oil into biodiesel.

Synthesis of sodium titanate catalysts using a factorial design for biodiesel production

AbstractIn this work, the synthesis of sodium titanate for the biodiesel production was evaluated with emphasis on the synthesis parameters of titanates in the conversion of vegetable oil to biodiesel. Sodium titanate catalysts were synthesized via sol–gel hydrothermal method and tested as heterogeneous catalysts for biodiesel production, using a factorial design 2k. Four experimental factors were considered: NaOH concentration, hydrothermal temperature, TiO2/NaOH ratio, and calcination temperature, using as response variable the catalysts activity in soybean oil conversion to biodiesel. Titanates were characterized by XRD, SEM, and N2 physisorption techniques. The presence of tri and hexatitanate were confirmed. Trititanate was the most efficient in the conversion of soybean oil to biodiesel, achieving around 80% with an alcohol:oil molar ratio of 6:1 at 55°C for 5 hr and 300 rpm. Among the trititanate catalysts, the best performing sample showed a surface area of 217 m2/g with a porous size average of 4.8 nm related to nanotube structure with inter and intra particle mesoporosity. Conditions to prepare the efficient performing catalyst were as follows: NaOH concentration, 7.5 M; hydrothermal temperature, 130°C; TiO2/NaOH ratio, 0.06 g/mL; and calcination temperature, 600°C.

Biodiesel Production Catalyzed by Polyvinyl Guanidineacetic Membrane

Polyvinyl guanidineacetic (PVG) was synthesized by the chemical grafting using poly (vinyl alcohol) (PVA) and guanidineacetic acid. The fourier transform infrared (FTIR), thermogravimetry (TG) and 1H nuclear magnetic resonance (1H NMR) results showed that the guanidineacetic groups were successfully introduced into the PVA. The effects of the amount of catalyst and reaction time on the PVG grafting rate were investigated. The PVG/non-woven fabrics (NWF) composite membrane as a heterogeneous catalyst for biodiesel production was successfully prepared by the solvent phase inversion. The effects of mass ratio of methanol/soybean oil, the IEC values of the composite membranes and reaction temperature on the transesterification conversions using the composite membrane for biodiesel were studied. The soybean oil conversion of 98.2% was obtained by the composite membranes under the optimum reaction conditions of reaction temperature of 338 K, methanol/oil mass ratio of 3:1, reaction time of 120 min and the alkali amount of catalytic membrane 18.0 mmol. After five runs, the conversion declined only 2.1%. And the kinetics of the reaction catalyzed by the composite membrane was performed as a first order reaction with an activation energy of 40.614 kJ/mol and pre-exponential factor of 7.60 × 104. The conversions obtained from the model are in good agreement with the experimental data. The quality of the biodiesel met the biodiesel requirements of Chinese Standard (GB/T 20828) and European Standard (EN 14214).

Synthesis of Epoxide and Polyol Compounds as Intermediates for Biolubricant from Soybean Oil

Biolubricant derived from vegetable oils is one of alternatives to substitute petroleum based lubricant. The biolubricant is environmental friendly, biodegradable, non toxic and renewable since it is derived from the vegetable oils. Soybean oil is potential as raw material for synthesis epoxide compound as intermediate substances for biolubricant since it has properties of high viscosity, low volatility, thermal stablity, vaporization stability and biodegradable. Polyol compound was produced through hydroxylation process of epoxide compound derived from the vegetable oils. The research aims to synthesize the epoxide compound from soybean oil, polyol compound synthesis from the epoxide compound and to determine kinetic reaction constants of the epoxidation and hydroxylation reactions. The process synthesis of the epoxide compound, as well as, polyol was carried out in a stirred glass reactors equipped with temperature measurement. The epoxidation reaction was carried out at 60 oC, 70 oC, and 80 oC with reaction time of 30 to 180 minutes with 30 minutes interval, while the hydroxylation reaction was carried out at 45 oC, 50 oC, 55 oC, and 60 oC with reaction time of 30 to 120 minutes with 30 minute interval. The highest conversion of soybean oil in epoxidation process was achieved 53.90 % at 70 oC and 120 minutes reaction time. The kinetic reaction constant for epoxidation reaction was achieved kep = 0.0046 min-1 at 70 oC. The highest conversion of hydroxylation process was achieved 91.52 % at 45 oC and 120 minutes reaction time. The kinetic reaction constant for hydroxylation reaction was achieved khd = 0.5528 min-1 at at 45 oC.

Electrochemical impedance: A new alternative to assess the soap removal from biodiesel in the washing process

An impedance- based sensor was built with stainless steel circular plates (7.0 cm2) to evaluate the soap limit for both biodiesels produced from commercial soybean oil and from waste cooking oil. Conversion of soybean oil to biodiesel was achieved with KOH and waste cooking oil was converted to biodiesel using NaOH. Various biodiesel batches were dry washed using a mixed ionic resin to remove charged carriers such as soaps. Based on the Nyquist and Bode plots as well as the physical shape of the sensor, an RbCb parallel circuit was used for modelling the experimental data. It was found that washing had a significant effect on Rb in comparison with the effect on Cb. From the impedance data acquired using the present sensor, an Rb value of 5 GΩ·cm2 was chosen as the minimum biodiesel resistance to assure a soap limit of below 41 ppm to comply with the currently accepted soap level in biodiesel.

Biodiesel production using a renewable mesoporous solid catalyst

Heterogeneous solid catalysts have been largely developed for biodiesel production, because of their attractive acid-base properties, strong hydrothermal stability, and efficient recovery/reusability. In this framework, developing bio-waste derived heterogeneous catalysts has attracted immense attention for several catalytic applications, owing to their inexpensive, high abundance, non-toxic, and adequate acid-base properties. In the present work, we investigated the catalytic performance of a biomass-derived orange peel ash (OPA), which contains a porous structure, as a raw heterogeneous catalyst for the transesterification of soybean oil to biodiesel. About 98 % conversion of soybean oil to biodiesel was obtained under the optimized reaction conditions i.e., 6:1 methanol:oil ratio, 7 wt. % catalyst loading, 7 h reaction time at ambient reaction temperature, which ascribed to the presence of abundant basic sites in the developed OPA catalyst. The catalyst can be reused for five successive cycles and shows good stability towards the biodiesel production.

Enhancement of biodiesel production via sequential esterification/transesterification over solid superacidic and superbasic catalysts

Abstract Recently, biodiesel can be produced from energy crops and has been recognized as an ideal candidate for satisfying the global energy demand. Owing to its fossil-fuel-similar physicochemical properties, biodiesel is also regarded as an alternative fuel for various applications. In present work, soybean oil with added fatty free acid (FFA; palmitic acid, 5.0 wt%) was converted to biodiesel via a two-step process in a catalytic fixed-bed batch reactor with SO42–/ZrO2/Al2O3, KF/CaO–Fe3O4, and Na/NaOH/Al2O3 catalysts. A solid superacidic (SO42–/ZrO2/Al2O3: 0.1–1.5 M H2SO4) and two solid superbasic (KF/CaO–Fe3O4, 5–25 wt% KF; Na/NaOH/Al2O3, 10–25 wt% NaOH) catalysts were fabricated using calcination at 300–700 °C and 200–700 °C, respectively. Notably, the FFA removal efficiency of SO42–/ZrO2/Al2O3 (80.0%) was much higher than that of commercial Amberlyst IR 120 (30.0%) in a 3-h reaction. Optimal biodiesel yields were obtained using KF/CaO–Fe3O4 (83.0%) and Na/NaOH/Al2O3 (100.0%). Catalytic reaction mechanisms of the conversion of soybean oil with FFA into biodiesel using solid superacidic and superbasic catalysts were also proposed. The FFA and soybean oil were converted to biodiesel over the superacidic and superbasic catalysts, respectively.