Simultaneous Transesterification Research Articles

Synthesis of the acidic/magnetic catalyst x-MoO3/Ni0.5Zn0.5Fe2O4 by combustion reaction and evaluation of its catalytic potential/reuse in biodiesel production

The objective of this work was to synthesize a new catalyst x-MoO3/Ni0.5Zn0.5Fe2O4 using the combustion reaction method and to evaluate its catalytic potential and reuse in biodiesel production from waste oil, optimizing the process through experimental design. The catalysts were characterized in terms of structure by X-ray diffraction and phase quantification by Rietveld refinement, surface area by the Brunauer-Emmett-Teller technique, experimental density by helium pycnometry, acidity tests by ammonia desorption at programmed temperature, chemical analysis by X-ray fluorescence, morphology by scanning and transmission electron microscopy, and catalytic properties. The products of the simultaneous transesterification and esterification reactions were characterized by gas chromatography and acidity index. The results indicate the formation of catalysts with surface area ranging from 1.5 to 1.7 m2/g and density ranging from 4.5 to 5.1 g/cm3, composed of major crystalline phases of MoO3 in the orthorhombic configuration and cubic Ni0.5Zn0.5Fe2O4 ferrite, with total acidity ranging from 70 to 182 μmol/g of NH3. Morphological characterization revealed that the catalyst comprises irregular plates of various sizes and shapes with a wide range of cluster sizes. In the simultaneous transesterification and esterification reactions of residual oil, the catalysts were active under all conditions tested, with emphasis on the catalyst containing 50 % Mo ions and 50 % Ni0.5Zn0.5Fe2O4 presenting the best catalytic performance with a conversion of 95 % in ethyl esters and a reduction of 71 % in acidity, with a service life of 6 cycles, an average conversion of 90 % and good thermal and structural stability after use. The experimental design was significant and predictive, with a confidence level of 95 %. Statistical analysis identified that all input variables (temperature, time, and amount of catalyst) were significant for the adopted design. The new catalyst composed of molybdenum, iron, nickel, and zinc has a positive impact on biodiesel synthesis from frying oil and ethanol.

Simultaneous geraniol and citronellol transesterification using Pseudomonas fluorescens lipase for the production of fragrance and flavour esters: A kinetic study

This study aims to develop, for the very first time, a kinetic model for the simultaneous transesterification of geraniol and citronellol using Pseudomonas fluorescens lipase to produce their respective esters. This allows us to test the feasibility of the bioprocess and comprehend the enzyme behaviour, fine-tune process efficiency, and predict process performance. Geranyl and citronellyl esters are key ingredients in fragrance and flavour formulations in the food sector, as well as bioactive compounds for pest and insect repellents in the agricultural sector. Unlocking a greener and sustainable production of these terpene esters directly from plant-derived essential oil is crucial to meet the 2050 net zero targets to produce bio-based chemicals. The simultaneous transesterification of geraniol and citronellol in a batch reactor successfully achieved conversions of 66 % for citronellol and 94 % for geraniol within 5 h. Key optimum conditions were 1:8 molar ratio (geraniol:vinyl acetate), an enzyme loading of 10 wt % of geraniol, temperature of 40 °C, and a stirring speed of 250 RPM. The results indicated that simultaneous transesterification followed a ternary complex mechanism with competitive inhibition by alcohol. Initial testing of rose geranium oil under optimised conditions yielded 32 % citronellol and 50 % geraniol conversion after 30 h. Overall, this study shows promise as a green pathway utilising enzyme catalysis to selectively produce esters from diverse terpene mixtures and can be extended to terpene alcohols derived from flower essential oils.

Biodiesel Production from Waste Cooking Oil via β-Zeolite-Supported Sulfated Metal Oxide Catalyst Systems.

Waste cooking oil (WCO) is a readily available and cheap feedstock for biodiesel production. However, WCO contains high levels of free fatty acids (FFAs), which negatively impact the biodiesel yield if homogeneous catalysts are used. Heterogeneous solid acid catalysts are preferred for low-cost feedstocks because the catalysts are highly insensitive to high levels of FFA in the feedstock. Therefore, in the present study, we synthesized and evaluated different solid catalysts, pure β-zeolite, ZnO-β-zeolite, and SO42-/ZnO-β-zeolite for the production of biodiesel using WCO as feedstock. The synthesized catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), pyridine-FTIR, N2 adsorption-desorption, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy, while the biodiesel product was analyzed using nuclear magnetic resonance (1H and 13C NMR) and gas chromatography-mass spectroscopy. The results revealed that the SO42-/ZnO-β-zeolite catalyst showed excellent catalytic performance for simultaneous transesterification and esterification of WCO, with a higher percentage conversion than the ZnO-β-zeolite and pure β-zeolite catalyst, due to the large pore size and high acidity. The SO42-/ZnO-β-zeolite catalyst exhibits 6.5 nm pore size, a total pore volume of 0.17 cm3/g, and high surface area of 250.26 m2/g. Experimental parameters such as catalyst loading, methanol:oil molar ratio, temperature, and reaction time were varied in order to establish the optimal parameters. The highest WCO conversion of 96.9% was obtained using the SO42-/ZnO-β-zeolite catalyst under an optimum reaction condition of 3.0 wt % catalyst loading, 200 °C reaction temperature, and 15:1 molar ratio of methanol to oil in 8 h reaction time. The WCO-derived biodiesel properties conform to the ASTM6751 standard specification. Our investigation of its kinetics revealed that the reaction follows a pseudo first-order kinetic model, with an activation energy (Ea) of 38.58 kJ/mol. Moreover, the stability and reusability of the catalysts were evaluated, and it was found that the SO42-/ZnO-β-zeolite catalyst exhibited good stability, giving a biodiesel conversion of over 80% after three synthesis cycles.

Biodiesel Production from Waste Oil Catalysed by Metal-Organic Framework (MOF-5): Insights on Activity and Mechanism

The activity of MOF-5-based solids has been exploited in the simultaneous transesterification and esterification of acid vegetable oils. For this purpose, three different types of MOF-5 have been synthesized and characterized, and then tested in the above-mentioned reactions. It has been demonstrated that the “regular MOF-5” was a suitable catalyst for biodiesel synthesis from waste oil also, rich in FFA (Free Fatty Acids). Moreover, to identify the true structure that acts in the reactions and possible structural modifications due to the presence of alcohols, proper studies have been performed. The results have evidenced a distortion of the regular structure of MOF-5 due to the breakage of some zinc bonds between the cluster and organic framework.

Synthesis of MgO/MgSO4 nanocatalyst by thiourea–nitrate solution combustion for biodiesel production from waste cooking oil

A novel MgO/MgSO4 nanocatalyst was synthesized using solution combustion method with thiourea as the fuel. The in-situ inducement of sulfonated group over the basic catalyst, MgO, was carried out for the first time using thiourea for the production of biodiesel. The synthesized nanocatalyst with its bi-functional characteristics performed efficiently in the simultaneous transesterification and esterification of high free fatty acid (FFA) containing waste cooking oil (WCO) into biodiesel in the presence of ultrasound. The newly developed nanocatalyst was characterized by XRD, FESEM, EDS, FTIR and BET analyses. The resulting nanocatalyst possesses a specific surface area of 82 m2/g and a pore volume of 0.047 cm3/g. The high sulfur content of 13.65% of the novel catalyst developed facilitates its high acidic characteristics suitable for the esterification step. The optimization of the process carried out by the response surface methodology (RSM) predicted the optimized parameters as follows: methanol to oil molar ratio-9.4:1, catalyst loading-8.9 wt%, ultrasonic power-402 W and reaction time-46 min. The optimum yield of biodiesel predicted by the RSM was 98.8%. The synthesized nanocatalyst demonstrated high stability which established significant future perspective for industrial production of biodiesel from low cost, high FFA containing feedstock.

Synthesis and catalytic properties of calcium oxide obtained from organic ash over a titanium nanocatalyst for biodiesel production from dairy scum

The fatty acid methyl ester (FAME) production from dairy effluent scum as a sustainable energy source using CaO obtained from organic ash over titanium dioxide nanoparticles (TNPs) as the transesterification nano-catalyst has been studied. The physical and chemical properties of the synthesized catalysts were characterized, and the effect of different experimental factors on the biodiesel yield was studied. It was revealed that the CaO–TiO2 nano-catalyst displayed bifunctional properties, has both basic and acid phases, and leads to various effects on the catalyst activity in the transesterification process. These bifunctional properties are critical for achieving simultaneous transesterification of dairy scum oil feedstock. According to the reaction results, the catalyst without and with a low ratio of TNPs showed a low catalytic activity. In contrast, the 3Ca–3Ti nano-catalyst had the highest catalytic activity and a strong potential for reusability, producing a maximum biodiesel yield of 97.2% for a 3 wt% catalyst, 1:20 oil to methanol molar ratio for the dairy scum, and a reaction temperature of 70 °C for a period of 120 min under a 300 kPa pressure. The physical properties of the produced biodiesel are within the EN14214 standards.

Data‐Driven Modeling of Biodiesel Production Using Artificial Neural Networks

AbstractData‐driven modeling of biodiesel production was developed by simultaneous transesterification and esterification of rapeseed oil and myristic acid with methanol, without catalyst or with different amounts of sulfated zirconia catalyst. An artificial neural network (ANN)‐based model was created with experimental literature data. The input data, i.e., reaction time, catalyst, temperature, and methanol‐to‐oil ratio, and output data, i.e., total fatty acid methyl ester and oleic acid methyl ester, were considered to develop the model. Multiple input single output (MISO) ANN architecture was taken to predict the above targeted two output parameters. The proposed ANN model is computationally efficient and works reasonably well when tested on biodiesel production for solving the MISO model.

Repeated Biodiesel Production Using a Cartridge Containing Solid Catalysts Manufactured from Waste Scallop Shells for Simultaneous Lipid Extraction and Transesterification Process

Biodiesel was produced from waste coffee grounds (WCGs) using solid catalysts manufactured from waste scallop shells through a one-step direct process (OSDP) comprising lipid extraction and simultaneous transesterification in a reactor. To facilitate the reuse of the solid catalysts, a cartridge containing the solid catalysts was devised, and the optimal conditions of the OSDP with the cartridge were investigated. Agitation speed was a critical factor for the operation of this novel process, and should be at least 200 rpm. The optimal total volume of the mixture consisting of methanol and n-hexane (9 mL/g-WCGs) was determined, along with the volume fraction of methanol (18.0%) and n-hexane (82.0%) using a statistical Mixture-Design technique. The optimum catalyst concentration (5.0 wt%), temperature (50°C), and reaction time (13 h) were determined through a Full Factorial Design, followed by a One-Factor-at-a-Time technique. Under these optimum conditions, 8.7% of biodiesel yield was obtained. The concentration of solid catalysts in the cartridge significantly influenced the reuse number of the cartridge. The cartridge containing 5.0 wt% of solid catalysts was reused only for the 2nd round of operation, while that containing 100 wt% of solid catalysts was successfully reused until the 12th round of operation, without a noticeable decrease in biodiesel yield.

Potassium and 12‐tungstophosphoric acid loaded alumina as heterogeneous catalyst for the esterification as well as transesterification of waste cooking oil in a single pot

AbstractTo prepare the heterogeneous catalyst for the simultaneous transesterification and esterification of waste cooking oil (WO), 12‐tungustophosphoric acid (TPA) and K+ were loaded over alumina. The catalyst structure was confirmed by powder X‐ray diffraction analysis while the catalyst composition and the elemental oxidation state by X‐ray photoelectron spectroscopic study. The surface morphology of the catalyst was established by high‐resolution transmission electron microscopy. The temperature‐programmed desorption study supports the existence of basic and acidic sites over the catalyst surface owing to the presence of potassium oxide and TPA, respectively. Underneath the optimized conditions for reaction, that is, 10 wt% of catalyst with respect to oil, 9:1 methanol to oil molar ratio and 65°C reaction temperature, 97% fatty acid methyl ester (FAME) yield was obtained within 1.25 h of reaction time. The catalyst was recovered from the reaction mixture via centrifugation and reused in four consecutive runs. Moreover, the presence of high moisture (4 wt%) and free fatty acid (7.8 wt%) contents was not found to have any adverse effect on the catalyst activity. To demonstrate the catalyst stability, the metal content in the reaction mixture was analyzed, and total metal content was found to be less than 2 ppm to hold the catalyst stability. The kinetic study suggests that the reaction follows (pseudo) first‐order kinetic equation with the prepared catalyst.

Synthesis of the ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 magnetic catalyst in pilot-scale by combustion reaction and its application on the biodiesel production process from oil residual

A magnetic catalyst with composition ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 was synthesized by a combustion reaction on a pilot-scale and applied in the conversion of residual oil into biodiesel by simultaneous transesterification and esterification reactions (TES). For that, statistical analysis of the factors that influence the process (catalyst concentration, alcoholic route, and temperature) was evaluated by 23 factorial experimental design. The ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 magnetic catalyst was characterized in terms of the structure, morphology, magnetic, TPD-NH3 acidity analysis and catalytic properties. The results indicate the formation of a catalyst with a surface area of 52.9 m2g−1, and density of the sample was 4.8 g/cm3 which is consisted of a mixture of the phases containing 55.87% Fe2O3, 36.96% Ni0.5Zn0.5Fe2O4, and 7.16% ZnO. The magnetic characterization indicated that the synthesized catalyst is ferromagnetic with magnetization 6.12 emu/g and coercive field of 5.3 G. In the TES reactions, the residual oil was active showing conversion to 96.16% ethyl esters and with a long useful life maintaining sustained activity after two consecutive reuse cycles with the conversion of 95.27%, 93.07% and 76.93%, respectively. The experimental design was significant and presented a 95% reliability level. The statistical analysis identified (+1) and (−1) as higher and lower level variables, respectively. The amount of catalyst used was equal to 5%, at 200 °C in methyl alcohol (alcoholic route). In summary, a new catalyst composed of a mixture of magnetically active phases was developed and successfully applied in biodiesel’s synthesis from residual oil. Undoubtedly these results have a positive and significant impact on the environment and to society as a whole.

Biodiesel production via simultaneous transesterification and esterification reactions over SrO–ZnO/Al2O3 as a bifunctional catalyst using high acidic waste cooking oil

A simultaneous transesterification and esterification process was applied for production of biodiesel from high acidic waste cooking oil containing 18 wt% FFA using a range of heterogeneous bifunctional strontium–zinc–aluminium catalyst. The influence of the molar ratio of metal oxide, the ethanol to waste oil molar ratio, temperature and time of reaction, catalyst dosage, and free fatty acids in the feedstock on the conversion of biodiesel were studied. High interaction between Sr, Al and Zn metal was recognised to promote catalyst performance. A high interaction and mixing of strontium, aluminium and zinc oxides enhanced and increased the active sites on the surface of acid and base. The catalyst with a 2.6:1 M ratio of strontium to zinc was found to perform the best to transesterify the glycerides and esterify the fatty acid in the used oil simultaneously. The catalyst exhibited higher catalytic activity with high acidity waste cooking oil, with 95.7% reaction conversion at the optimum conditions 10:1 ethanol to waste oil molar ratio, 15 wt% catalyst dosage, and 5 h reaction time at 75 °C reaction temperature. The used catalyst showed low reusability due to high leaching of strontium.

Kinetic modeling and development of optimal trajectories for biodiesel production using multi-objective optimization

A kinetic model has been developed based on the experimental data in the open literature for the simultaneous esterification of myristic acid and transesterification of rapeseed oil with methanol by using sulphated zirconia catalyst at three different temperatures (120 °C, 150 °C, 170 °C) and methanol to oil ratio (20:1). The developed kinetic model has been utilized for the cross-validation of methanol to oil ratio of 10:1 and 4:1 and at a temperature of 170 °C, which is in accordance with the experimental data. Furthermore, the validated kinetic model has been extended to find the optimal process conditions for the desired conflicting objectives. Trade-off solutions for this process are obtained by utilizing the non-dominated sorting genetic algorithm (NSGA-II). The objective is to obtain maximum FAME (fatty acid methyl ester) in minimum methanol to oil ratio and minimum reaction temperature. Addition of oil, methanol, myristic acid and temperature are considered as decision variables with relevant process constraints. A wide range of choices have been obtained for the present optimization setup. The yield of FAME is strongly depends on the reaction temperature, reaction time and methanol to oil ratio. The optimal methanol to oil ratio of 10–15 is sufficient to enhance the FAME yield. • Kinetic modeling of simultaneous Transesterification and esterification. • Kinetic parameter estimation using RCGA. • Formulation of Multi-objective optimization. • Pareto optimal set obtained for the desired conflicting objectives.

Repeated Biodiesel Production from Waste Coffee Grounds via a One-step Direct Process with a Cartridge Containing Solid Catalysts Manufactured from Waste Eggshells

In this study, biodiesel was produced from waste coffee grounds (WCGs) using solid catalysts manufactured from waste eggshells (WESs). A one-step direct process (OSDP), comprising extraction of lipids from WCGs and simultaneous transesterification of these lipids with methanol in a reactor, was employed. To facilitate reuse of the solid catalysts, a cartridge containing the solid catalysts was devised and applied in the OSDP. The optimal reaction conditions of the OSDP with the cartridge were 100 wt% catalyst relative to WCGs, the mixture of 4.0 mL methanol and 4.0 mL n-hexane per gram WCG, 45°C, 9 h, and 200 rpm. Under these optimal conditions, an 8.7% biodiesel yield (g-biodiesel/g-WCGs) was achieved. Solid catalysts retained in the cartridge were successfully reused for seven rounds of repeated batch operation and, using this approach, a biodiesel yield exceeding 92% of that of the first batch operation was maintained.

Optimization of Biodiesel Production from Waste Coffee Grounds by Simultaneous Lipid Extraction and Transesterification

We previously optimized a conventional twostep process (TSP) for biodiesel production using waste coffee grounds (WCGs). In the present study, a novel process, one-step direct process (OSDP) comprised of lipid extraction and simultaneous transesterification in a reactor, was evaluated for biodiesel production for WCGs, and compared with TSP. Owing to a relatively low free-fatty acid content (2.3%), an alkaline catalyst, NaOH, was readily used in this process. We found that a mixture of methanol and n-hexane was the best combination for the OSDP. Optimization of OSDP was conducted by statistical technique, followed by one-factor-at-a-time and sensitivity analysis techniques. Using these techniques, 10.8% (gbiodiesel/ g-WCGs) biodiesel yield was achieved at 3.0 wt% of catalyst relative to WCGs, 3.0 mL methanol/g-WCGs, 4.5mL n-hexane/g-WCGs, 45°C, and 9 h of reaction time. Compared to the TSP, the OSDP saved methanol and n-hexane requirement by 69.7% and 67.2%, respectively, while the actual biodiesel yields based on the lipid amount in WCGs were similar in both processes. This study showed that the novel OSDP could be a promising alternative to TSP for economic biodiesel production from WCGs.

Using ethanol for continuous biodiesel production with trace catalyst and CO2 co-solvent

The continuous biodiesel production process under sub- and supercritical conditions using a trace amount of potassium hydroxide (KOH) as a catalyst has been studied. CO2 was added as a co-solvent to reduce the reaction time and increase biodiesel yield. The proposed procedure enables simultaneous transesterification and esterification of triglycerides and free fatty acid (FFA), respectively. The shorter reaction time and milder reaction conditions may reduce energy consumption due to the simplification of the separation and purification steps. The process variables, including reaction temperature, ethanol to oil molar ratio, catalyst amount, and process pressure, were systematically optimized. The highest biodiesel yield (98.12%) was obtained after a 25-min reaction time using only 0.11% wt. of KOH and a 20:1 ethanol to oil ratio. The process optimum temperature and pressure were 240 °C and 120 bar, respectively. The proposed kinetic model suggested a first-order reaction with an activation energy of 15.7 kJ·mol−1 and a reaction rate constant of 0.0398/min−1. The thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy were calculated as 144.82 kJ·mol−1, 11.4 kJ·mol−1, −0.26 kJ·mol−1 and at 240 °C, respectively.

Synthesis of Fatty Acid Methyl Esters from Pomace Oil Catalyzed by Zinc Stearate: A Kinetic Study of the Transesterification and Esterification Reactions

In this work, the simultaneous transesterification and esterification reactions of olive pomace oil with methanol catalyzed by zinc stearate were studied. This catalyst is a crystalline solid at room temperature, but it is soluble in the reaction medium at reaction temperature. Zinc stearate has surfactant properties that cause the formation of an emulsion in the reaction system. The stability of the emulsion formed in the oil–methanol–catalyst system was compared to that in the FAME (fatty acid methyl esters)–methanol–catalyst system. It was observed that the emulsion formed in the presence of high amounts of FAME is much more unstable, which makes the catalyst easy to separate from the reaction products. The kinetics of esterification and transesterification were also studied. All the kinetic and equilibrium constants were determined with a complete model, considering the three stepwise reactions corresponding to the transesterification of triglycerides and the esterification of free fatty acids. The parameters obtained were used to model the operating conditions that would allow obtaining biodiesel that meets the quality standards.

Immobilized polymeric sulfonated ionic liquid on core-shell structured Fe3O4/SiO2 composites: A magnetically recyclable catalyst for simultaneous transesterification and esterifications of low-cost oils to biodiesel

In accordance with the need of green and sustainable development, a magnetically recyclable solid catalyst was developed for the transformation of low-cost oils to biodiesel via simultaneous transesterification and esterifications in an efficient and environmentally benign manner. For this aim, the magnetic Fe3O4/SiO2 composites composed of iron oxides as the core and silica as the shell, were prepared, and then polymeric acidic ionic liquid (IL) was immobilized on the magnetic support through radical grafting copolymerization of Brønsted acidic IL, 1-vinyl-3-(3-sulfopropyl)imidazolium hydrogen sulfate, onto the magnetic support. The characterization results showed that the perfect core-shell structured Fe3O4/SiO2 support with good magnetic responsiveness was formed, and the polymeric acidic IL was tethered on the magnetic support. The combination of polymeric acidic IL with magnetic porous nanoparticles could enhance the catalytic activity and favored the separation performance of the catalyst. The solid catalyst exhibited high activities for both transesterification of soybean oil and esterification of free fatty acids generally presented in low-cost oils. Moreover, the catalyst could be simply recovered magnetically and efficiently reutilized for several times without significant loss in its activity, thus allowing its being potentially applicable for green and economic production of biodiesel especially from the low-cost oil feedstocks.

Biodiesel Production from Acidic Oils Using Polyoxometalate-Based Sulfonated Ionic Liquids Functionalized Metal–Organic Frameworks

An efficient and recyclable catalyst, namely phosphomolybdenum-based sulfonated ionic liquids (ILs) functionalized MIL-100(Fe) metal–organic framework (AIL/HPMo/MIL-100(Fe)), was developed for the production of biodiesel via the transesterification-esterifications of acidic oils. For this goal, the MIL-100(Fe) metal–organic framework (MOF) was initially modified with phosphomolybdic acid (HPMo), and then the acidic ionic liquid (AIL) was immobilized on the prepared HPMo/MIL-100(Fe) composite through ion-exchange of 1-(propyl-3-sulfonate)imidazolium hydrogen sulfate with HPMo. The as-developed AIL/HPMo/MIL-100(Fe) catalyst possessed enhanced surface acidities, endowing the merits of Lewis and Bronsted acids with a heterogeneous microreactor of MOFs and favoring the better catalytic performance. The characterization results corroborated that the polyoxometalate-based ILs were incorporated into the MIL-100(Fe), and the porous structure of the MIL-100(Fe) maintained nearly unchangeable after the synthesis processes. The AIL/HPMo/MIL-100(Fe) catalyst could perform simultaneous transesterification of soybean oil and esterification of free fatty acids (FFAs) with long-term catalytic durability. The conversion of acidic oils using this solid catalyst gave 92.3% oil conversion for the transesterification of soybean oil and full FFA conversion for the esterification of FFAs with the methanol/oil molar ratio of 30:1 at 120 °C, showing potential applications for the production of biodiesel particularly from acidic oil feedstocks. Synopsis: Phosphomolybdenum-based sulfonated ionic liquids (ILs) functionalized MIL-100(Fe) metal–organic framework composites are fabricated and then utilized as efficient and recyclable catalysts for the production of biodiesel via one-pot transesterification-esterifications of acidic oils.

Immobilization of polyoxometalate-based sulfonated ionic liquids on UiO-66-2COOH metal-organic frameworks for biodiesel production via one-pot transesterification-esterification of acidic vegetable oils

In accordance with the need of green and cleaner production, the aim of the present study is to fabricate an organic-inorganic hybrid recyclable catalyst with both Brönsted and Lewis acid sites for the one-pot production of biodiesel from the low-cost acidic oil feedstocks. To achieve this, the UiO-66-2COOH metal-organic framework materials (MOFs) were firstly functionalized with Keggin-type polyoxometalate (POM) acids through the in-situ preparation strategy, and then the sulfonated acidic ionic liquids (AILs) were further incorporated into the prepared POM/UiO-66-2COOH composites by pairing polyoxometalate anions with functionalized IL cations. The as-prepared AILs/POM/UiO-66-2COOH solid catalyst features a high surface area and an increased acidity, thus combining the merits of Brönsted and Lewis acids together with the heterogeneous microenvironment of MOFs. The solid acid catalysts were fully characterized by several techniques, and the results demonstrated that the polyoxometalate-based sulfonated AILs were virtually immobilized on the UiO-66-2COOH MOFs, and furthermore the porous crystalline structure of the UiO-66-2COOH material was almost unaltered after the immobilization processes. The solid catalyst had excellent catalytic activities toward the simultaneous transesterification and esterification of simulated low-cost oils with long-term stability and good reusability, and moreover still remained considerable activities even with the existence of 9 wt% free fatty acid and 3 wt% water in the low-cost oils. Therefore, this solid catalyst shows potential applications for the one-step biodiesel production especially from the low-cost feedstocks which usually contain high amounts of free fatty acid and water.

Simultaneous transesterification and esterification of acidic oil feedstocks catalyzed by heterogeneous tungsten loaded bovine bone under mild conditions

Abstract A highly active bi-functional catalyst system for the conversion of high free fatty acid content oil feedstock, and waste cooking oil to fatty acid methyl ester (FAME), is described. Tungsten loaded CaO/hydroxyapatite materials containing both basic, and acidic sites were derived from addition of 12-phosphotungstic acid to powdered bovine bone (BV), followed by calcination at 750 °C. Addition of 10% tungsten afforded 10 W/BV, which catalyzes FAME production from high acid value oil feedstock (24.38 mg KOH/g of oil) in 7 h at 120 °C at a methanol:oil ratio of 6:1. Conversion of waste cooking oil to FAME via simultaneous transesterification/esterification can be achieved in 5 h at 100 °C and at a methanol:oil ratio of 6:1, significantly more efficient than achievable using other bi-functional catalyst systems. The 10 W/BV catalyst system, readily prepared from a cheap, biomass derived support containing basic sites, is reusable, and allows for the production of fuel quality FAME in high yields from waste cooking oil, allowing for sustainable use of an otherwise wasted resource.