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The synthesis of biodiesel can be achieved using either homogeneous or heterogeneous catalysts. Given the non-renewable nature of homogeneous catalysts, heterogeneous catalysts are increasingly preferred for biodiesel production. Agricultural wastes serve as a viable source for these heterogeneous catalysts, contributing to environmental sustainability. This study introduces a novel, eco-friendly, cost-effective, and efficient heterogeneous catalyst that was developed and derived from Citrus limetta peels for biodiesel production. The catalyst was thoroughly characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractograms (XRD), Field Emission Scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX). Coconut oil, a rich and renewable resource, was used as the feedstock for the biodiesel synthesis. The conversion process was confirmed by 1H NMR, IR spectra, mass spectra, and 13C NMR of the biodiesel. The developed method using the Citrus limetta peel-derived catalyst demonstrated a 100% yield. The results show the optimum conditions for biodiesel synthesis are 1 w/v (for the catalytical dose), with a 6:1 methanol/oil ratio at 60 °C for 3 h. The synthesized biodiesel exhibited a high cetane value of 54, contributing to improved ignition and reduced engine noise. Its sulfur-free composition, boiling point of 294 °C, high viscosity of 2.5 mm2/s, acid value of 0.09 mgKOH/g, and flash point of 142 °C enhance its environmental profile. The catalyst can be used for up to five cycles, underscoring its potential as a cost-effective and sustainable approach for biodiesel production. [ABSTRACT FROM AUTHOR]

Biofuels are one of the renewable fuels needed to replace fossil fuels. Making biofuels requires an acid/base catalyst to speed up the reaction, one of which is esterification. This study aimed to produce sulfonated carbon from coconut shells and water hyacinth, which was carbonized at 300 °C for 6 h. It was reacted with 96 % sulfuric acid at 150 °C with variations in sulfonation times and variations in sulfonation cycles. The highest acid concentration catalyst results were obtained on water hyacinth raw materials at 1.2 mmol/g and coconut shells at 1.215 mmol/g. The more sulfonation cycles will increase the acid concentration value. The value of the catalyst activity test in the esterification reaction of the water hyacinth catalyst can convert Free Fatty Acid (FFA) better than the coconut shell catalyst. Conversion of esters in the esterification process is 75.28 % in the water hyacinth catalyst and 57.62 % in the coconut shell catalyst. The coconut shell and water hyacinth catalysts were sulfonated in the presence of Fourier Transform Infra-Red (FTIR) absorption spectra at wave numbers 1,035.77 cm-1 for the coconut catalyst and 1,033.85 cm-1 for the water hyacinth catalyst, which is a strong S=O group. The Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis results indicate that the carbon sulfonate acid catalyst is amorphous. The constant kinetics of the water hyacinth catalyst reaction is 0.0139 L/mol.h, while for the coconut shell catalyst, it is 0.0045 L/mol.h. Coconut shell and water hyacinth raw materials can be used as heterogeneous acid catalysts after sulfonation. [ABSTRACT FROM AUTHOR]

The synthesis of biodiesel can be achieved using either homogeneous or heterogeneous catalysts. Given the non-renewable nature of homogeneous catalysts, heterogeneous catalysts are increasingly preferred for biodiesel production. Agricultural wastes serve as a viable source for these heterogeneous catalysts, contributing to environmental sustainability. This study introduces a novel, eco-friendly, cost-effective, and efficient heterogeneous catalyst that was developed and derived from Citrus limetta peels for biodiesel production. The catalyst was thoroughly characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractograms (XRD), Field Emission Scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX). Coconut oil, a rich and renewable resource, was used as the feedstock for the biodiesel synthesis. The conversion process was confirmed by 1H NMR, IR spectra, mass spectra, and 13C NMR of the biodiesel. The developed method using the Citrus limetta peel-derived catalyst demonstrated a 100% yield. The results show the optimum conditions for biodiesel synthesis are 1 w/v (for the catalytical dose), with a 6:1 methanol/oil ratio at 60 °C for 3 h. The synthesized biodiesel exhibited a high cetane value of 54, contributing to improved ignition and reduced engine noise. Its sulfur-free composition, boiling point of 294 °C, high viscosity of 2.5 mm2/s, acid value of 0.09 mgKOH/g, and flash point of 142 °C enhance its environmental profile. The catalyst can be used for up to five cycles, underscoring its potential as a cost-effective and sustainable approach for biodiesel production.

In this study, a new catalyst for heterogeneous acid based on molybdenum oxide (MoO 3) supported over graphene oxide (GO) was synthesized and applied in simultaneous esterification-transesterification reactions using waste cooking oil (WCO) to obtain biodiesel. In the catalyst synthesis, the GO support was synthesized from graphite oxidation, followed by wet MoO 3 impregnation. The MoO 3 /GO catalyst was characterized by Surface Acidity, Thermogravimetric Analysis (TG/DTG), X-ray Diffraction (XRD), Fourier Transformation Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Energy Dispersion X-ray Spectroscopy (EDS). The application of the catalyst in the conversion of WCO into biodiesel had as parameters reaction temperature (120.0–160.0 °C), reaction time (1.0–5.0 h), catalyst loading of (2.0–10.0%) and methanol:oil molar ratio of (25:1–45:1). The results of the catalytic tests showed the best condition of biodiesel synthesis was 140.0 °C reaction temperature, 5.0 h of reaction time, 6.0% catalyst loading and 35:1 methanol:oil molar ratio, leading to a biodiesel with ester content of 95.6%. The catalyst showed good recovery and excellent catalytic performance in the reuse study, producing biodiesel with ester content above 70.0% after 5 reaction cycles. Thus, this study shows a promising new catalyst of heterogeneous acid with high catalytic activity and applicability in the biodiesel synthesis process. [Display omitted] [ABSTRACT FROM AUTHOR]

This research is providing a method for the synthesis of 2,4,5‐trisubstituted imidazole derivatives based on pursuing the green chemistry principles. Therefore, a one‐pot multicomponent cyclocondensation reaction through aldehyde interaction with ammonium acetate and 1,2‐diketone was carried out in EtOH:H2O solvent under ultrasound irradiation. This protocol was utilized as an eco‐effective synthetic route by applying CoFe2O4@SiO2@(‐CH2)3OWO3H nanocomposite as a nanocatalyst. The stabilized tungstic acid on 3‐chloropropyl anchored to SiO2‐coated CoFe2O4 magnetic nanoparticles was designed, prepared, and applied as a recyclable heterogeneous acid catalyst to attain high product yields and short reaction times. The structure of nanocatalyst was confirmed by using Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) techniques, and the obtained organic derivatives were examined through melting point, FT‐IR, and 1H NMR analyses. [ABSTRACT FROM AUTHOR]

This study has identified a new feedstock Chukrasia tabularis L. (C. tabularis) seed for the production of biodiesel. Oil was extracted from the seeds with and without autoclave-assisted ultrasonic homogenization (AUH) pretreatment using different solvents. The solvent n-hexane with AUH pretreatment yielded a maximum oil yield of 32 wt%. The kinetics and thermodynamics of the extraction process were studied in a batch. The data showed that extraction followed first-order kinetics with a rate constant of 1.4 × 10−4 min−1, activation energy of 63.604 kJ mol−1 and pre-exponential factors of 66.66 × 104 s−1. The physiochemical properties of the oil were determined from which it was identified that C. tabularis oil has high free fatty acid (FFA) content, requiring a single-step esterification cum transesterification reaction to produce biodiesel economically. The modified aryl diazonium salt reduction process was used to synthesize a heterogeneous acid catalyst (HAC) from activated carbon precursor and was used to catalyze biodiesel reaction. Furthermore, HAC was characterized by different analytical techniques and it was found that it had an acid site density of 1.02 mmol g−1 and a specific surface area of 602 m2 g−1. The parameters affecting the biodiesel process were studied to obtain a maximum biodiesel conversion of 98.5% at 6 wt% catalyst loading, 15:1 methanol to oil molar ratio, 120 min reaction time, 70 ºC reaction temperature, and 500 rpm stirring rate. Reusability studies were performed which showed that HAC can be recycled up to five cycles with a conversion above 90% in the fifth cycle. Moreover, the fuel properties of biodiesel were determined using standard methods and were compared with ASTM D6751 and EN14241 standards. [ABSTRACT FROM AUTHOR]

This work investigates the optimization of reaction parameters with the Taguchi method for catalytic deoxygenation of waste cooking oil (WCO) as an alternative renewable fuel process. Commercial sulphated-ferric (II) oxide/alumina oxide catalyst has the potential as a deoxygenation catalyst due to its good physicochemical properties which enhance the removal of oxygenated species. The obtained pyrolysis oil analysed by GC-MS revealed the selectivity of the pyrolysis oil mostly in the range of light diesel and kerosene fraction. From an analysis of variance (ANOVA), temperature awarded the most significant impact (86.62%) in this catalytic deoxygenation as compared to three other parameters followed by reaction time > N2 flow > catalyst loading. From the GC-MS analysis, the maximum renewable diesel fraction of 49.66% was obtained at 400 °C, 1 wt% of catalyst, 90 min of reaction time and 20 cm3/min N2 flow. The predicted model by Taguchi in the present study validated by the experimental work shows a promising application in optimising the catalytic pyrolysis process for future use.

In this study, poly(hydroxyethyl methacrylate) [P(HEMA)] microsphere-supported sulfuric acid [P(HEMA)-SO3H] was prepared as a novel heterogenous solid acid catalyst and its catalytic activity was investigated in the synthesis of amides via Ritter reaction. The P(HEMA) microspheres were synthesized via suspension polymerization and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer, Emmett and Teller surface area and energy dispersive X-ray (EDX) analyses. The specific surface area and the pore volume of the microspheres were determined as 33.80 m2/g and 1.490 cm3/g, respectively. The pore size was in the range of 9.18–122.59 A°. The specific surface area of P(HEMA)-SO3H catalyst was 26.24 m2/g decreasing after modification with sulfo groups. FTIR, SEM and EDX analyses demonstrated that P(HEMA) microspheres were successfully modified with sulfo groups. The acidity of P(HEMA)-SO3H catalyst was determined as to 7.48 ± 0.16 mmol H+/g P(HEMA)-SO3H catalyst by titration with standardized NaOH solution. The catalyst was then successfully applied in the Ritter reaction to prepare a series of different amides in high to excellent yields. The P(HEMA)-SO3H catalyst was recovered and reused four times without a significant decrease in the catalytic activity. The other advantages of this novel catalyst include excellent yield, short reaction time and solvent-free conditions. [ABSTRACT FROM AUTHOR]

A novel magnetically separable Fe 3 O 4 @biochar@SO 3 H catalyst was developed from mesua assamica (King & prain) waste seed shells biochar for cost-effective biodiesel production using novel mesua assamica seed oil, jatropha oil, and soybean oil. The magnetic solid acid catalyst was synthesized via impregnation of biochar with Fe 3 O 4 magnetic nanoparticles followed by sulfonation techniques. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis suggested the successful sulfonation and existence of –SO 3 H groups on catalyst surface. The synthesized magnetic acidic catalyst possesses total acidity of 3.9 mmol g−1 and –SO 3 H density of 1.8 mmol g−1. The field emission transmission electron microscopy (FETEM) led core-shell structured catalyst particle demonstrated a mean size of 87.4 nm and the surface area of 71.47 m2 g−1. The acidic catalyst easily afforded maximum yield of 96.8% mesua assamica biodiesel, 95.3% jatropha biodiesel, and 95.8% soybean biodiesel under optimized reaction parameters. The kinetic investigation suggested the occurrence of pseudo first order kinetics with activation energy of 32.42 kJ mol−1. The magnetically separable catalyst also displayed promising activity and stability up to 3rd cycle with more than 75% biodiesel yield. [Display omitted] • Matured mesua assamica seeds expressed maximum 29% oil. • Mean size and surface area of acidic nanocatalyst was 87.4 nm and 71.47 m2 g−1. • Acidity and –SO 3 H density of the catalyst was 3.9 mmol g−1 and of 1.8 mmol g−1. • The maximum biodiesel yield was 96.8% at fresh cycle and 75% at 3rd recycle. [ABSTRACT FROM AUTHOR]

Global environmental concern and the diminishing of fossil fuel escalated the seek for the development of renewable alternative fuels such as biodiesel. Biodiesel can be produced via transesterification and esterification reactions, expedited with a suitable homogeneous or heterogeneous catalyst. Heterogeneous catalyst offers high activity and high selectivity; and this is due to the chemical and physical properties of the catalyst. Heterogeneous catalyst can be produced from various sources such as metal oxides and its derivatives; and bio-wastes containing carbon sources which are heterogeneous in nature. Lately, the utilization of sulfonated carbon acid catalyst becomes increasingly attractive due to its advantages and potential to replace homogeneous and heterogeneous catalysts in the biodiesel manufacturing industry. The catalyst is environmentally benign and can effectively convert free fatty acid to alkyl ester. Sulfonated carbon acid catalyst can be prepared by incorporating sulfonation agent which contains sulfonic group into the carbonaceous material. The performance of sulfonated carbon acid catalyst is highly dependent on the treatment condition and its starting material. This review focuses on the recent invention and use of the sulfonic group bearing porous carbon heterogeneous catalysts for biodiesel production. [Display omitted] • Sulfonic group bearing porous carbon catalyst for biodiesel formation is reviewed. • Sulfonated carbon acid catalysts were prepared from synthetic and natural carbon. • Synthetic carbon includes carbon nanotube and ordered mesoporous carbon. • SO 3 H group can be incorporated into carbonaceous material using two techniques. • Leaching of SO 3 H group will deactivate sulfonated carbon acid catalyst. [ABSTRACT FROM AUTHOR]

A new magnetically recoverable heterogeneous acid catalyst was easily synthesized by electrostatic interaction of phosphotungstic acid (HPW) species with 3-aminopyridine (Ampy) modified magnetite-silica heterostructure (Fe 3 O 4 /SiO 2 -Ampy-HPW). The step by step modification of magnetite nanoparticles along with structural stability, and maintenance of magnetization and morphology of bare magnetite nanoparticles after chemical functionalization steps were confirmed by various physicochemical techniques. The size of these nanoparticles was obtained to be 10–30 nm from TEM analysis, which was in accordance with the data estimated from XRD technique. Also, it was observed that the presence of HPW on the surface of catalyst has increased the acid content of catalyst. Catalytic property of Fe 3 O 4 /SiO 2 -Ampy-HPW catalyst was assessed in acid-catalyzed ring opening of epoxides with alcohols. According to the results obtained at optimum reaction condition, the prepared catalyst exhibited good performance (conversion of 93%) with high selectivity (100%) in methanolysis of styrene oxide compared to the unfunctionalized Fe 3 O 4 /SiO 2 , which is definitely due to the presence of HPW acidic species on the surface of Fe 3 O 4 /SiO 2. Moreover, other epoxides and alcohols were tested in this catalytic system, which subsequently, reasonable results with more or less conversion were obtained based on the types of the epoxides and alcohols used. [Display omitted] • A new heterogeneous acid catalyst was successfully synthesized based on magnetite nanoparticles. • The simple electrostatic interaction was applied to immobilize HPW on the surface of MNPs. • The immobilized HPW played an important role as strong acidic site in alcoholysis of epoxides. • Good conversions of epoxides with different alcohols were obtained at optimized reaction condition. [ABSTRACT FROM AUTHOR]

In this study, the silver-exchanged heteropolyacids were prepared by a simple and environmentally friendly ion exchange method, were found to be active in the esterification of oleic acid with methanol to produce biodiesel. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the oleic acid conversion can reach 91.3% after reacting for 3 h at 70°C, with oleic acid to methanol ratio of 1:10 and the amount of catalyst of 5 wt.%. Moreover, the catalyst could be easily separated from the reaction mixture and used repeatedly for five cycles with the oleic acid conversion over 50.1%, due to its relative stability. In particular, this catalyst can also catalyze other esterification of fatty acids with different chain length of carboxylic acid and high acid value non-edible oils, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel in the future. [ABSTRACT FROM AUTHOR]

The current work investigates biodiesel synthesis from the cheaper source- palm fatty acid distillate (PFAD) using HClSO3–ZrO2 acid catalyst. The effect of various physicochemical parameters such as molar ratio, catalyst loading, temperature, molecular sieves addition, and agitation speed was studied. The maximum conversion of 91.5% and yield of 90.2% was achieved in 150 min under the reaction conditions of molar ratio 8:1, amount of catalyst 3.5 wt%, 60 °C, agitation speed 250 rpm, and molecular sieves 5 wt%. While comparing the catalytic activity with Amberlyst-15 in converting PFAD to FAME, it was found that HClSO3–ZrO2 gave 7.2 times more conversion as compared to Ambetlyst-15 for similar reaction conditions. Catalyst reusability was also tested and showed a negligible decrease in the conversion at least for three cycles. The kinetics and thermodynamics properties were investigated with the help of Arrhenius equation and Eyring reaction rate theory. The physicochemical properties of the purified PFAD biodiesel were compared with the petroleum diesel and also matched with American Society for Testing and Materials (ASTM) standards and found within the limit. [ABSTRACT FROM AUTHOR]

Fatty acid sugar esters are non-ionic surfactant active agents with excellent performance and many uses. This work is devoted to the synthesis of sugar esters by the esterification reaction of sugar with mixed carboxylicpalmitic anhydrides using resin Amberlyst-15 as heterogeneous acid catalyst. These anhydrides should be stable and react as acylating agents. Influence of different reaction parameters, such as the molar ratio (sucrose/anhydride), the type of solvent and the reaction time on the yield of the esterification reaction were studied. The esterification reaction of sucrose with mixed palmitic benzoic anhydride leads to a mixture of sucrose esters of palmitic acid with a good percentage of conversion. The mixed anhydride was both reactive and selective for the preparation of fatty acid ester. [ABSTRACT FROM AUTHOR]

In recent years, a new class of superior heterogeneous acid catalyst for biodiesel production has emerged. These catalysts offer advantages over their predecessors such as high surface area, elevated acid site density, enhanced catalyst activity, good operation stability and relevant economic affordability in an environmentally friendly frame. This review was concerned with carbon-based solid acid (CBAS) catalysts derived from both carbohydrate and pyrolysis products. A series of CBASs with various origins such as D-glucose, sucrose, starch, cellulose and vegetable oil asphalt, converted to char and sulphonated, have been explored as potential heterogeneous catalysts. Catalyst preparation and synthesis methods were briefly summarized. Catalyst characterization and performance for biofuels related reactions were elucidated, identifying potential research applications. Three catalysts in particular were identified as having potential for industrial application and requiring further research. [ABSTRACT FROM AUTHOR]

Anchored propyl sulfonic acid on the surface of silica-coated magnetic nanoparticles (Fe3O4@SiO2@PrSO3H) was successfully employed in the deprotection of TBDMS ethers. The prepared magnetically separable nanocatalyst exhibited efficient catalytic activity with high conversion and selectivity in cleavage of TBDMS ethers. TBDMS ethers are efficiently cleaved to the corresponding hydroxyl compounds in methanol solution containing 2 mol% magnetic nano-catalysts. Good to excellent yields of products, simple work-up and product separation, selective cleavage of TBDMS ethers in the presence of TBDPS ethers, easy recycling of the catalyst with external magnet with no loss in its activity (7 reaction cycles) are important features of this new protocol. [ABSTRACT FROM AUTHOR]

Zr-MOF (UiO-66) catalysts PTSA/UiO-66 and MSA/UiO-66 bearing supported sulfonic acids (p-toluenesulfonic acid and methanesulfonic acid, respectively) were prepared through a simple impregnation approach. The UiO-66-supported sulfonic acid catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The prepared heterogeneous acid catalysts had excellent stability since their crystalline structure was not changed compared with that of the original UiO-66. Zr-MOF MSA/UiO-66 and PTSA/UiO-66 were next successfully used as heterogeneous acid catalysts for the esterification of biomass-derived fatty acids (e.g., palmitic acid, oleic acid) with various alcohols (e.g., methanol, n-butanol). The results demonstrated that both of them had high activity and excellent reusability (more than nine successive cycles) in esterification reactions. Alcohols with higher polarity (e.g., methanol) affected the solid catalyst reusability slightly, while alcohols with moderate or lower polarity (e.g., n-butanol, n-decanol) had no influence. Thus, these developed sulfonic acids-supported metal-organic frameworks (UiO-66) have the potential for use in biodiesel production with excellent reusability.

In recent years, a new class of superior heterogeneous acid catalyst for biodiesel production has emerged. These catalysts offer advantages over their predecessors such as high surface area, elevated acid site density, enhanced catalyst activity, good operation stability and relevant economic affordability in an environmentally friendly frame. This review was concerned with carbon-based solid acid (CBAS) catalysts derived from both carbohydrate and pyrolysis products. A series of CBASs with various origins such as D-glucose, sucrose, starch, cellulose and vegetable oil asphalt, converted to char and sulphonated, have been explored as potential heterogeneous catalysts. Catalyst preparation and synthesis methods were briefly summarized. Catalyst characterization and performance for biofuels related reactions were elucidated, identifying potential research applications. Three catalysts in particular were identified as having potential for industrial application and requiring further research.

Due to rapid changes in food habits, a substantial amount of waste fat and used oils are generated each year. Due to strong policies, the disposal of this material into nearby sewers causes ecological and environmental problems in many parts of the world. For efficient management, waste cooking oil, a less expensive, alternative and promising feedstock, can be used as a raw material for producing biofuel. In the present study, we produced a biodiesel from hydrolyzed waste cooking oil with a subcritical methanol process using a synthesized solid super acid catalyst, a sulfated zirconium oxide supported on Santa Barbara Amorphous silica (S-ZrO2/SBA-15). The characterization of the synthesized catalyst was carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), and the Brunauer-Emmett-Teller (BET) method. The catalytic effect on biodiesel production was examined by varying the parameters: temperatures of 120 to 200 °C, 5-20 min times, oil-to-methanol mole ratios between 1:5 to 1:20, and catalyst loadings of 1-2.5%. The maximum biodiesel yield was 96.383%, obtained under optimum reaction conditions of 140 °°C, 10 min, and a 1:10 oil-to-methanol molar ratio with a 2.0% catalyst loading. We successfully reused the catalyst five times without regeneration with a 90% efficiency. The fuel properties were found to be within the limits set by the biodiesel standard. [ABSTRACT FROM AUTHOR]

The magnesium hydroxide fluorides, MgFx(OH)2-x with different aging temperatures have been synthesized by the sol-gel method. The resulting materials were characterized by various techniques such as XRD, FT-IR, TG/DTG, N2 adsorption-desorption, pyridine FT-IR and SEM, respectively. The catalytic evaluation of samples was investigated in the simultaneous transesterification and esterification between waste cooking oil (WCO) containing different %FFA and methanol to yield biodiesel. The performance of the catalyst, especially MgFx(OH)2-x aged at room temperature (RT) showed higher biodiesel yield compared to MgFx(OH)2-x with increasing of aging temperature. The higher catalytic activity could be attributed to Brønsted acid site, pore diameter size and volume of the materials. Moreover, the yield of biodiesel was not correlated with the surface area of MgFx(OH)2-x.The reusability or lifetime of catalyst decreased after three runs used. [ABSTRACT FROM AUTHOR]

The utilization of base catalyst for two-step transesterification prompts soap formation and yield loss in biodiesel production. In order to overcome this difficulty, the two-step transesterification process was performed with homogeneous base catalyst and heterogeneous acid catalyst was performed in the batch reactor and the high-pressure apparatus. As per response surface methodology, optimum condition for the first step is determined. The ester content of 85% is obtained with the molar ratio of methanol to oil of 5.48:1, 0.32 wt% of CH 3 ONa catalyst, 40 min and at 55 °C. Final biodiesel production with ester content of 98% is produced from the second step under optimum condition (methanol/oil molar ratio of 10, Amberlyst 15 catalyst content of 12 wt%, 9 h and 115 °C). The soap content was 50% and amount of base catalyst used was 33% as compared to one-step transesterification process. [ABSTRACT FROM AUTHOR]

With the aim to enhance the direct conversion of raw corn stover into furfural, a promising approach was proposed employing a novel heterogeneous strong acid catalyst (SC-CaC t -700) in different solvents. The novel catalyst was characterized by elemental analysis, N 2 adsorption-desorption, FT-IR, XPS, TEM and SEM. The developed catalytic system demonstrated superior efficacy for furfural production from raw corn stover. The effects of reaction temperature, residence time, catalyst loading, substrate concentration and solvent were investigated and optimized. 93% furfural yield was obtained from 150 mg corn stover at 200 °C in 100 min using 45 mg catalyst in γ-valerolactone (GVL). In comparison, 51.5% furfural yield was achieved in aqueous media under the same conditions (200 °C, 5 h, and 45 mg catalyst), which is of great industrial interest. Furfural was obtained from both hemicelluloses and cellulose in corn stover, which demonstrated a promising routine to make the full use of biomass. [ABSTRACT FROM AUTHOR]

An environmentally friendly method is described for the synthesis of various isoindoline-1,3-dione derivatives from the reaction of phthalic anhydride with aromatic/aliphatic amines in ethanol at 80 °C by phthalimide- N-sulfonic acid as an efficient heterogeneous acid catalyst. Some advantages include the metal-free and environmentally friendly protocol, simple operation and reusable processes, easy recovery, short reaction times, and high yields. [ABSTRACT FROM AUTHOR]

The aim of this research was to synthesize, characterize, and apply a heterogeneous acid catalyst to optimum biodiesel production from hydrolyzed waste cooking oil via an esterification reaction, to meet society’s future demands. The solid acid catalyst S–TiO2/SBA-15 was synthesized by a direct wet impregnation method. The prepared catalyst was evaluated using analytical techniques, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and the Brunauer–Emmett–Teller (BET) method. The statistical analysis of variance (ANOVA) was studied to validate the experimental results. The catalytic effect on biodiesel production was examined by varying the parameters as follows: temperatures of 160 to 220 °C, 20–35 min reaction time, methanol-to-oil mole ratio between 5:1 and 20:1, and catalyst loading of 0.5%–1.25%. The maximum biodiesel yield was 94.96 ± 0.12% obtained under the optimum reaction conditions of 200 °C, 30 min, and 1:15 oil to methanol molar ratio with 1.0% catalyst loading. The catalyst was reused successfully three times with 90% efficiency without regeneration. The fuel properties of the produced biodiesel were found to be within the limits set by the specifications of the biodiesel standard. This solid acid catalytic method can replace the conventional homogeneous catalyzed transesterification of waste cooking oil for biodiesel production.

A novel highly efficient magnetically retrievable catalyst was developed by the immobilization of HPWO (20-60 wt%) on the surface of zirconia-encapsulated FeO nanoparticles. The prepared HPW supported on nano-FeO@ZrO heterogeneous acid catalyst (or n-FeO@ZrO/HPW) was fully characterized by several physicochemical techniques such as: Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometry and thermogravimetric analysis. The FT-IR spectroscopic data revealed that HPWO molecules on the nano-FeO@ZrO support existed in the Keggin structure. The acidity of the catalyst was measured by the help of a potentiometric titration with n-butylamine. It was surprising that this very strong solid acid catalyst exhibited an excellent acid strength which was as a result of possessing a higher number of surface active sites compared to its homogeneous analogues. The catalytic activity of the as-prepared novel nano-FeO@ZrO/HPW was explored through the one-pot three-component synthesis of different 3,4-dihydropyrimidin-2(1 H)-ones (i.e. Biginelli reaction) and 1,4-dihydropyridines (i.e. Hantzsh reaction) under solvent free condition. The sample of 40 wt% showed higher acidity and activity in the catalytic transformation. After the reaction, the catalyst/product isolation could be easily achieved with an external magnetic field and the catalyst could be easily recycled for at least five times without any decrease in its high catalytic activity. The excellent recyclability was attributed to the strong interaction between the hydroxyl groups of the nano-FeO@ZrO support and the HPW species. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Compared to carboxylic acids, carboxylic anhydrides are efficient acylating agents. Mixed anhydrides are appreciated in organic chemistry because of their high reactivity. They are finding an increasing interest in the chemical industry. This work describes a novel and efficient method of synthesis of fatty esters by the esterification reaction with mixed carboxylic fatty anhydrides, using heterogeneous acid catalyst. These anhydrides, characterized by the general formula RCOOCOC 15 H 31 , can be easily prepared by the reaction of palmitic acid with the acid chloride in organic solvent and in the presence of triethylamine as acid acceptor. These anhydrides should be stable and react as acylating agents. [ABSTRACT FROM AUTHOR]

Alkyl glucosides surfactants are synthesized by a cascade process that involves the methanolysis of cellulose into methyl glucosides followed by the transacetalization with n-octanol. The first step was performed using methanol as solvent and acid catalysts (such as, inorganic acids, heteropolyacids, ionexchange resins, or modified carbon materials). Subsequently, long-chain alkyl glucosides are obtained in the second step by transacetalization, which involves the reaction of methyl glucosides with a fatty alcohol using the same acid catalyst. The overall process was performed under mild conditions. Amorphous sulfonated carbon catalyst achieved the best results for the complete conversion of cellulose in methanol at 200 °C with methyl α,β-glucopyranosides yields higher than 80 %. Moreover, this material containing −SO3H groups is ideal to perform the second step to obtain octyl and decyl glucosides in yields higher than 73 % at 120 °C. In addition, the sulfonated carbon catalyst (C−SO3H) can be reused with only a slightly decrease of its activity after four consecutive cycles. [ABSTRACT FROM AUTHOR]

Due to rapid changes in food habits, a substantial amount of waste fat and used oils are generated each year. Due to strong policies, the disposal of this material into nearby sewers causes ecological and environmental problems in many parts of the world. For efficient management, waste cooking oil, a less expensive, alternative and promising feedstock, can be used as a raw material for producing biofuel. In the present study, we produced a biodiesel from hydrolyzed waste cooking oil with a subcritical methanol process using a synthesized solid super acid catalyst, a sulfated zirconium oxide supported on Santa Barbara Amorphous silica (S-ZrO2/SBA-15). The characterization of the synthesized catalyst was carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), and the Brunauer-Emmett-Teller (BET) method. The catalytic effect on biodiesel production was examined by varying the parameters: temperatures of 120 to 200 °C, 5–20 min times, oil-to-methanol mole ratios between 1:5 to 1:20, and catalyst loadings of 1–2.5%. The maximum biodiesel yield was 96.383%, obtained under optimum reaction conditions of 140 °C, 10 min, and a 1:10 oil-to-methanol molar ratio with a 2.0% catalyst loading. We successfully reused the catalyst five times without regeneration with a 90% efficiency. The fuel properties were found to be within the limits set by the biodiesel standard.

Heterogeneous acid catalysts are derived from bamboo through the method of partial carbonization with sulfonation in succession and the catalytic activity is validated through the esterification of oleic acid with ethanol for biodiesel production. Meanwhile, catalysts are characterized by thermogravimetric (TG), nitrogen adsorption, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and acid–base titration. Under the optimal conditions of carbonization at 350 °C with 2 h duration and sulfonation at 105 °C with 2 h duration, the bamboo derived catalyst possesses amorphous carbon structure with high sulfur content. It shows considerable heat stability below 220 °C and gains the total acid amount of 1.74 mmol g − 1 . This catalyst could supply the esterification efficiency of 98.4% for acid value reduction with the molar ratio of ethanol to oleic acid of 7, heterogeneous acid addition of 6%, esterification temperature of 90 °C and esterification time of 2 h. In addition, the reused catalyst could be satisfyingly reactivated with the esterification activity of 93.66% under the same esterification condition. [ABSTRACT FROM AUTHOR]

A simple preparation of sulfonated-silica/carbon (SiO 2 /C–SO 3 H) composites from rice husk at different carbonization temperatures have been demonstrated. These composites have been employed as heterogeneous Brønsted acid catalysts in converting fructose into methyl levulinate (ML) in a one-pot reaction that involves dehydration, etherification, and rehydration processes. As the carbonization temperature increased, the results from N 2 adsorption-desorption isotherm showed porosity and the surface area of the composites were increased. The acid strength was also increased, as confirmed by the Temperature-Programmed Desorption of Ammonia (NH 3 -TPD) profile. Energy-Dispersive X-ray (EDX) analysis revealed the SiO 2 /C weight ratios of the composite were increased, but S/C weight ratios were decreased. 90% yield of ML was synthesized at 165 °C for 7 h in methanol solvent. Pearson's correlation test showed that hydrophilicity is the main factor in obtaining high turnover number (TON). The yield was dropped in recycling experiments due to carbonaceous deposition, which caused deactivation, as corroborated by the Thermogravimetric Analysis (TGA) and N 2 sorption analysis. These composites were also able to convert fructose into 56–74% yield of 5-hydroxymethylfurfural (HMF) in dimethylsulfoxide (DMSO) solvent at 130 °C for 5 h. [Display omitted] • Facile method to synthesize series of strong heterogeneous Brønsted acid catalysts. • Use an agricultural waste; rice husk as a naturally-occurring SiO 2 & C precursors. • Physicochemical properties determine their catalytic performances. • Maneuvering SiO 2 /C wt % ratio is critical to achieve maximum TON. • Higher hydrophilicity (SiO 2 /C wt% ratio) facilitate fructose adsorption hence better interaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] A facile approach for the selective synthesis of succinic acid (SA) using solid acid catalyst in aqueous media. [•] Oxidative cleavage of furan carbonyls (furfural, 5-hydroxymethyl-2-furaldehyde, furoic acid) to SA. [•] Use of Amberlyst-15 (solid acid catalyst) and 30% H2O2 (green oxidant) under mild conditions. [•] Remarkable activity with excellent recyclability. [ABSTRACT FROM AUTHOR]

Abstract: The transesterification of soybean oil with methanol to fatty acid methyl ester (FAME) was carried out using WO3/SnO2 solid as a heterogeneous acid catalyst. The effects of catalyst preparation parameters on the conversion to FAME were investigated. This WO3/SnO2 catalyst prepared by an impregnation method, with the WO3 loading amount of 30% and calcined at a temperature of 1173K, showed the best catalytic activity. The maximum conversion to FAME of 79.2% was achieved after 5h at 383K when 30:1M ratio of methanol to oil and 5wt.% of catalyst were employed. The ability of the catalyst to esterify free fatty acids (FFAs) in feedstocks and its insensitivity to water exhibited the potential to prepare biodiesel from low-cost feedstocks. The solid catalyst can be reused for four runs without significant deactivation. [Copyright &y& Elsevier]

Abstract: Utilization of macroalgae biomass for bioethanol production appears as an alternative source to lignocellulosic materials. In this study, for the first time, Amberlyst (TM)-15 was explored as a potential catalyst to hydrolyze carbohydrates from Eucheuma cottonii extract to simple reducing sugar prior to fermentation process. Several important hydrolysis parameters were studied for process optimization including catalyst loading (2–5%, w/v), reaction temperature (110–130°C), reaction time (0–2.5h) and biomass loading (5.5–15.5%, w/v). Optimum sugar yield of 39.7% was attained based on the following optimum conditions: reaction temperature at 120°C, catalyst loading of 4% (w/v), 12.5% (w/v) of biomass concentration and reaction time of 1.5h. Fermentation of the hydrolysate using Saccharomyces cerevisiae produced 0.33g/g of bioethanol yield with an efficiency of 65%. The strategy of combining heterogeneous-catalyzed hydrolysis and fermentation with S. cerevisiae could be a feasible strategy to produce bioethanol from macroalgae biomass. [Copyright &y& Elsevier]

Abstract: WO3/AlPO4 catalysts were prepared by impregnation of AlPO4 with ammonium metatungstate. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric and differential thermal analysis (TG–DTA) demonstrated that the tungsten compound was incorporated into AlPO4 forming the catalyst with an enhanced acidity. When transesterification of soybean oil over the catalysts was performed, the catalyst with 30wt.% WO3 loading and calcined at 1073K, exhibited the best catalytic activity with a conversion of 72.5%. The transesterification was optimal at 453K for 5h with a methanol/oil ratio of 30:1 and catalyst dosage of 5wt.%. Free fatty acid (FFA) and water did not affect the catalytic activity. The catalyst proved to be stable over four transesterification cycles as it lost only 4% of its activity after being reused four times. The catalyst could be used for the transesterification of low-cost oils for biodiesel production. [Copyright &y& Elsevier]

Abstract: A new heterogeneous acid catalyst system for production of environmentally friendly fuel, biodiesel was created from ferric sulfate and non-toxic, inexpensive source of biopolymer, sodium alginate. The catalyst, in the form of ferric-alginate beads produced from the reaction of 2wt.% sodium alginate gel with 0.1M ferric sulfate solution gave excellent methyl ester conversion of 98% with mild reaction conditions. The esterification of 0.5g lauric acid was carried out at optimum conditions; 16wt.% of ferric-alginate beads (2.8wt.% Fe) methanol refluxing temperature, 15:1 methanol to lauric acid molar ratio for 3h. The ferric-alginate beads were reusable up to 7 times without any pre-treatment. Characterization of the ferric-alginate beads showed the formation of FeOOH that held the alginate chain in place. Thermal analysis showed that the beads are able to withstand the refluxing temperature without degradation. Iron content was found to be 0.175g Fe/g beads as determined by AAS and 0.189g Fe/g beads as determined by TGA. Easy catalyst separation, reusability and ability of the ferric-alginate beads to esterify lauric acid to give high conversion of methyl laurate makes this catalyst desirable for biodiesel production from high free fatty acid oils. [Copyright &y& Elsevier]

Abstract: The transesterification of soybean oil with methanol was carried out, to produce biodiesel, over silica-bonded N-propyl sulfamic acid in a heterogeneous manner. Results showed that a maximum conversion of 90.5% was achieved using a 1:20M ratio of soybean oil to methanol and a catalyst amount of 7.5wt.% at 423K for 60h. It was found that the free fatty acid (FFA) and water present in the feedstock had no significant influence on the catalytic activity to the transesterification reaction. Besides, the catalyst also showed activities towards the esterification reaction of FFAs, in terms of the FFA conversion of 95.6% at 423K for 30h. Furthermore, the catalyst could be recovered with a better reusability. [Copyright &y& Elsevier]

Abstract: Biodiesel was produced from waste frying oil (WFO) by the two step catalyzed process. The free fatty acids (FFA) were first esterified with methanol catalyzed by SiO2 pretreated with HF. The catalyst was characterized by its acid surface sites, FTIR, SEM, and, its CO2 and H2O adsorption reactivity. This catalyst was easy to recover, was not hydrated or carbonated, was not dissolved by the reactants or the products of the reaction, showed a high activity for the FFA esterification and presented high stability. After 10 esterification runs, the catalyst activity remained unchanged. During the second step, the triglycerides in WFO were transesterified with methanol catalyzed by NaOH. The biodiesel obtained was characterized by its physical properties and its chemical composition. Gas chromatography and mass spectrometry analysis revealed that the process proposed in this investigation led to a biodiesel containing 96% methyl esters. [Copyright &y& Elsevier]

Abstract: Solid acid catalysts are normally used to catalyze the transesterification of oil with high free fatty acid (FFA) to biodiesel. However, the immiscible phases of methanol-oil-catalyst in the initial reaction mixture usually lead to slow reaction rate and long reaction time. One possible way to overcome this limitation is by using co-solvent that has high solubility in oil and methanol. Therefore, in the present study, the use of biodiesel as co-solvent for transesterification reaction catalyzed by (solid acid catalyst) was investigated. It was found that with the use of biodiesel as co-solvent, a high FAME yield of 88.2% (almost 30% higher than without using co-solvent) can be obtained in a shorter reaction time (1.5h) using the following reaction conditions; reaction temperature of 150°C, methanol to oil ratio of 15 and catalyst loading of 6wt.% (weight of oil). [Copyright &y& Elsevier]

Abstract: A high quality biodiesel was produced from Mexican Jatropha curcas crude oil (JCCO) by a two step catalyzed process. The free fatty acids (FFA) were first esterified with methanol, catalyzed by a solid catalyst: SiO2 pretreated with HF. The catalyst showed a high number of Lewis acid surface sites, and no CO2 or H2O adsorption activity. This catalyst showed a high FFA esterification activity and high stability. After 30 esterification runs, the catalyst activity remained unchanged. During the second step, the triglycerides present in the JCCO were transesterified with methanol catalyzed by NaOH. The chromatographic analysis of the biodiesel obtained, revealed that the process proposed in this investigation led to a very high quality biodiesel, meeting the international requirements for its utilization as a fuel. The combustion gas emissions of the JCCO biodiesel were studied by FTIR spectroscopy using a laboratory combustor. These preliminary results showed low amounts of aromatic and sulfur containing compounds. However, halogenated compounds and dicyclopentadiene were also detected at the combustor exhaust. [Copyright &y& Elsevier]

Abstract: This study presents the feasibility of converting a non-edible oil source native to the Africa region –croton megalocarpus oil to methyl esters (biodiesel) using sulfated tin oxide enhanced with SiO2 (/SnO2–SiO2) as super acid solid catalyst. This study was conducted using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (α)=2. The reaction parameters studied are: reaction temperature (60–180°C), reaction period (1–3h) and methanol to oil ratio (1:6–1:24). Although the oil was found to contain high free fatty acid, however, yield up to 95% was obtained without any pre-treatment step with the following reaction conditions: 180°C, 2h and 15:1 methanol to oil molar ratio, while keeping constant catalyst concentration and stirring speed at 3wt.% and 350–360rpm, respectively. [Copyright &y& Elsevier]

Abstract: A promising catalyst based on a biomass pyrolysis by-product, biochar, has been developed for the production of biodiesel. Two carbon-based solid acid catalysts were prepared by sulfonating pyrolysis char with concentrated or fuming sulfuric acids. Prepared catalysts were studied for their ability to catalyze transesterification of vegetable oils and esterification of free fatty acids. The catalyst sulfonated with the concentrated sulfuric acid demonstrated considerable conversion in free fatty acid esterification, while indicating limited transesterification activity. Using the stronger sulfonating reagent, fuming sulfuric acid, resulted in much higher transesterification activity. Further investigation of the latter catalyst was conducted to determine the effect of sulfonation time (5 and 15h) and surface area on the transesterification reaction. The surface area of the biochar was increased by chemical treatment using 10M potassium hydroxide through porosity development. The resulting four catalysts were compared for their catalytic activity. Results showed the catalyst with the highest surface area and acid density to have the highest catalytic activity for the production of biodiesel from canola oil in the presence of methanol as the reagent. Furthermore, the catalyst with the higher surface area indicated higher transesterification activity among the catalyst with similar acid densities. The effects of alcohol to oil (A:O) molar ratio, reaction time and catalyst loading on the esterification reaction catalyzed by the sulfonated biochar were also investigated. Free fatty acid (FFA) conversion increased with increasing A:O molar ratio, reaction time and catalyst loading. The catalyst has a tremendous potential to be used in a process converting a high FFA feedstock to biodiesel. [Copyright &y& Elsevier]

Abstract: An integrated, clean, facile and ecologically friendly approach of biodiesel production from Eruca Sativa Gars (ESG) vegetable oil focused on lab scaling up was reported in this study. Transesterification of ESG oil was heterogeneously catalyzed by Cs2.5H0.5PW12O40 heteropolyacid salt. The properties of biodiesel from ESG were comparable to conventional diesel fuel and comply with the US Standard for Biodiesel (ASTM 6751). Using ESG biodiesel instead of conventional diesel fuel reduces emissions. The results illustrate that the Cs2.5H0.5PW12O40 is an environmentally benign solid acid catalyst and ESG biodiesel is a kind of nontoxic and biodegradable renewable alternative fuel. [Copyright &y& Elsevier]

In recent years, various kinds of heterogeneous acid catalysts have been prepared and utilized for different catalytic applications. Among them, designing the easily recoverable catalysts containing two distinct Brønsted acidic sites with enhanced catalytic properties is promising. In this work, modification of the mesopores of MCM-41 as a siliceous solid support with two suitable nitrogen-containing amino- and piperazine-propylsilyl groups followed by covalent interaction with 1,4-butane sultone introduced sulfonic acid groups to this mesoporous material. The additional electrostatic interaction with phosphotungstic acid groups generated the second acidic sites on ammonium and piperazinium moieties. The successful synthesis of these solid acid catalysts was confirmed by FT-IR, energy dispersive X-ray (EDX), and inductively coupled plasma optical emission (ICP-OES) spectroscopies; CHN elemental analysis; nitrogen sorption; and XRD techniques. The catalytic experiments in benzaldehyde acetalization with ethylene glycol resulted in moderate to high activity from 76% to 97% within 2 h. Moreover, the higher catalytic activity was related to the one possessing two kinds of acidic sites due to the synergistic effect between these acidic sites. [Display omitted] • New solid acid catalysts were prepared via the functionalization of MCM-41 material. • The solid acid catalysts showed high activity in the acid-catalyzed acetalization reaction. • The catalysts were consecutively recovered and reused four times without significant loss of their activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrolysis and sulfonation convert starch-based plastic (SBP) bags into SO 3 H-catalyst. • SO 3 H-catalyst from SBP-bags well-catalyzes the esterification of fatty acids. • SO 3 H-catalyst from SBP-bags is robust and recyclable for more than 7 cycles. • Highly pure terephthalic acid self-precipitates from SBP-bags pyrolysis liquid. • Pyrolysis liquid is enriched in levoglucosan, adipic acid and monobutenyl esters. Pyrolysis was explored as a technology for depolymerizing and charring starch-based plastic bags in a novel valorization perspective based on a chemical recycling strategy, alternative to anaerobic digestion or composting. The char obtained from the thermal treatment (420°C for 15 h) was sulfonated to give a highly active and recyclable heterogeneous acid catalyst (10 wt% yield based on starch-based plastic bags subjected to pyrolysis), comparable in terms of catalytic activity and reusability to the analog catalyst prepared from potato starch and tested on a model esterification reaction. From pyrolysis liquid of starch-based plastic bags, highly pure terephthalic acid (4 wt% yield) was isolated through self-precipitation, whereas the remaining pyrolysis liquid produced (21 wt%) was solvent-fractionated to give a polar fraction (7 wt% yield) enriched in levoglucosan, and a less polar fraction (14 wt% yield) enriched in monobutenyl adipate and terephthalate. [ABSTRACT FROM AUTHOR]

Zr-MOF (UiO-66) catalysts PTSA/UiO-66 and MSA/UiO-66 bearing supported sulfonic acids (p-toluenesulfonic acid and methanesulfonic acid, respectively) were prepared through a simple impregnation approach. The UiO-66-supported sulfonic acid catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The prepared heterogeneous acid catalysts had excellent stability since their crystalline structure was not changed compared with that of the original UiO-66. Zr-MOF MSA/UiO-66 and PTSA/UiO-66 were next successfully used as heterogeneous acid catalysts for the esterification of biomass-derived fatty acids (e.g., palmitic acid, oleic acid) with various alcohols (e.g., methanol, n-butanol). The results demonstrated that both of them had high activity and excellent reusability (more than nine successive cycles) in esterification reactions. Alcohols with higher polarity (e.g., methanol) affected the solid catalyst reusability slightly, while alcohols with moderate or lower polarity (e.g., n-butanol, n-decanol) had no influence. Thus, these developed sulfonic acids-supported metal-organic frameworks (UiO-66) have the potential for use in biodiesel production with excellent reusability. [ABSTRACT FROM AUTHOR]