Heterogeneous Acid Catalyst Research Articles

Chiral Heterogeneous Scandium Lewis Acid Catalysts for Continuous-Flow Enantioselective Friedel-Crafts Carbon-Carbon Bond-Forming Reactions.

While continuous-flow reactions with chiral heterogeneous catalysts provide a highly efficient method to synthesize optically active compounds, chiral heterogeneous Lewis acid catalysis has been less extensively explored. We have developed the first example of chiral heterogeneous Sc catalysts, which demonstrated excellent activity and selectivity for continuous-flow enantioselective Friedel-Crafts reactions of isatins with indoles. Noncovalent interactions between chiral Sc complexes and heteropoly acid-anchored amine-functionalized SiO2 as support were utilized for the synthesis. The heteropoly acid was found to be crucial for the preparation, activity, and selectivity of the catalysts. The chiral ligand could be easily tuned without chemical modification and the continuous-flow synthesis of a biologically active compound was achieved.

Chiral Heterogeneous Scandium Lewis Acid Catalysts for Continuous‐Flow Enantioselective Friedel–Crafts Carbon–Carbon Bond‐Forming Reactions

AbstractWhile continuous‐flow reactions with chiral heterogeneous catalysts provide a highly efficient method to synthesize optically active compounds, chiral heterogeneous Lewis acid catalysis has been less extensively explored. We have developed the first example of chiral heterogeneous Sc catalysts, which demonstrated excellent activity and selectivity for continuous‐flow enantioselective Friedel–Crafts reactions of isatins with indoles. Noncovalent interactions between chiral Sc complexes and heteropoly acid‐anchored amine‐functionalized SiO2 as support were utilized for the synthesis. The heteropoly acid was found to be crucial for the preparation, activity, and selectivity of the catalysts. The chiral ligand could be easily tuned without chemical modification and the continuous‐flow synthesis of a biologically active compound was achieved.

Optimization of Trans-esterification Process and Characterization of Biodiesel from Soapstock Using Silica Sulfuric Acid as a Heterogeneous Solid Acid Catalyst

The main objective of this study was production, optimization, and fuel quality characterization of biodiesel from equal weight ratio blended acid oil of cottonseed and sunflower soapstock using silica sulfuric acid as a solid acid catalyst in laboratory scale. The physicochemical properties of soap stock samples and extracted acid oil from each soap stock were determined. The experiment was designed by design expert (version 11) software. The 5-level 4-factors (methanol to acid oil molar ratio, catalyst weight, stirring rate, and reaction time) were designed using the central composite design method. From the experimental results, the maximum biodiesel yield of 90.68% was obtained using methanol to acid oil molar ratio of 7:1 using catalyst 5.5(%wt/wt) with a stirring rate of 300rpm at 3hr reaction time. The average value of triplicate experiment of biodiesel yield from the experimentation at optimized condition was 92.62%. The analysis of variance results indicated that satisfactory results were achieved. The carried out physiochemical properties of produced biodiesel were within a range and some were closest to American and European biodiesel standards.

Pyrolytic conversion of waste edible oil into biofuel using sulphonated modified alumina

Bioenergy generated from vegetable oils is an interesting alternative energy source to fossil fuel in terms of reducing carbon footprint and realizing a circular economy. The catalytic cracking route is a promising method due to its capability to process a variety of feedstocks and its ability to produce a wide range of fuels. Catalytic pyrolysis of waste edible oil was performed using heterogeneous acidic catalyst synthesized through sulphonation of modified alumina. The optimum ratio of the catalyst was 0.8 wt%, relative to the used oil, to produce 88% of liquid biofuel. The acidity of the catalyst was determined, and the analysis showed high activity compared to the recently documented heterogeneous acidic catalysts. The physical properties of the obtained biofuel including viscosity, density, acid value, cloud, pour, flash points, and cetane number were in accordance with ASTM values. Furthermore, these values were better than those recently reported. The most effective process limitation was the deposition of coke during the process, which was in its minimal value at the selected catalyst ratio. The process mechanism was discussed based on oil fatty acid composition. Engine test investigated the obtained biofuel properties, and engine performance of biofuel-diesel blends showed the suitability of the B30 blend.

Synthesis, Characterization, Tribological and Rheological Properties of Oleyl Oleate Based Biolubricant

Oleyl oleate (liquid wax ester); is a principal component of sperm whale bubbler oil has an important industrial application such as cosmetic, pharmaceutical and biolubricant. In this work, synthesis of oleyl oleate was carried out through esterification between oleoyl alcohol and oleic acid using acidic heterogeneous catalyst, sodium hydrogen sulfate. About 95% of oleoyl oleate was produce at the optimal condition. The molecular structure of oleyl oleate has been confirmed by using FTIR, NMR and ESI-MS spectroscopies. The physicochemical properties of oleyl oleate were investigated. The results showed that the ester has pour point at -31 ± 1˚C, flash point at 320 ± 2˚C, viscosity index of 197.51 ± 1.4 and oxidative stability at 186.9 ˚C ± 1.8. Furthermore, tribological and rheological analysis of oleyl oleate were performed. Oleoyl oleate can be classified as a Newtonian fluid with having friction coefficient of 0.53 ± 0.08 at 100 ˚C operation condition. The presence of both ester functional group and long chain carbon moiety in oleyl oleate structure has a positive impact on wear protection thus plausible to be use as general purpose industrial biolubricant.

Sulfamic acid supported on mesoporous MCM-41 as a novel, efficient and reusable heterogenous solid acid catalyst for synthesis of xanthene, dihydropyrimidinone and coumarin derivatives

Herein, the incorporation sulfamic acid (SA) into mesoporous silica (MCM-41) introduced an effective approach in numerous multicomponent reactions. SA/MCM-41 composites with different weight content of SA were successfully synthesized through easy impregnation method. The as-synthesized composites were characterized by different techniques like SEM, EDX, TEM, XRD, BET and FT-IR spectroscopy. The acidic characters of the composites have been studied using FTIR of chemisorbed pyridine and non-aqueous potentiometric titration. TEM and XRD measurements approve that MCM-41 shows an ordered mesoporous structure with hexagonal and honeycomb lattice and its mesoporous structure did not change even after modification with SA. MCM-41 shows high surface area (1287 m 2 /g), which reduced after addition of sulfamic acid until reached to 611 m 2 /g at 90 wt% SA-MCM-41. The acidic strength of the prepared composites progressively improved by raising SA contents up to 75 wt% SA/MCM-41. The as-synthesized composites were tested for multicomponent reactions such as preparation of 3,4-dihydro-pirimidin-2(1H)-ones (DHPs), 7-hydroxy-4-methylcoumarin and 14-Phenyl-14H-dibenzo [a, j] xanthene. SA/MCM-41 catalysts displayed excellent performance in 14-phenyl-14H-dibenzo [a, j] xanthene (95.8%), 3, 4-dihydropyrimidinones (94.4%) and 7-hydroxy-4-methylcoumarin (96.7%). The prepared catalysts displayed excellent reusability without significant loss in catalytic performance from the fresh run. • A highly active and stable MCM-41 supported with sulfamic acid catalysts have been successfully synthesized. • All loaded catalysts exhibited distinct catalytic activity in synthesis of xanthene, dihydropyrimidinone and coumarin. • The catalysts showed an excellent yield % up to 95% in all reactions and also show excellent recycling efficiency.

Influence of synthesized catalyst on the pyrolytic conversion of waste oils into renewable biofuel: Synthesis and performance

The depletion of fossil fuel resources and the universal warming phenomenon gained the consideration of researchers to improve renewable and eco-friendly energy sources. Numerous routes were currently employed conventionally in the production of biofuels. The commercial production of biodiesel is performed catalytically either by transesterification using methanol to form fatty acid methyl esters or by pyrolysis using acidic or alkaline solid catalysts. Catalytic pyrolysis of waste edible oils was used as a resource for the production of biodiesel using synthetic chemically modified alumina catalyst. The catalyst was synthesized based on chemical modification of ZSM-5 platform by organic precursor followed by sulphonation, to yield highly effective acidic heterogeneous catalyst. The synthetic catalyst was characterized using FTIR, XRD, TPD, and TGA analysis to determine its chemical structure. Fuel properties, carbon dioxide emission, brake specific fuel consumption (BSFC), exhaust gas temperature (EGT), and brake thermal efficiency (BTE) properties of the obtained biodiesel and its blends with petroleum diesel were determined to investigate the efficiency of the catalyst and the performance of the biodiesel. The chemical composition of the biodiesel produced was the key factor of the efficiency of the different biodiesel-petroleum diesel performance as an economic and eco-friendly alternative energy source.

Catalytic activity and stability of sulfonic-functionalized UiO-66 and MIL-101 materials in friedel-crafts acylation reaction

Sulfonic-containing UiO-66 and MIL-101 MOF materials, prepared by direct synthesis with a sulfonic acid-including benzene dicarboxylate (SO3H-BDC) linker, have been evaluated as acid catalysts in Friedel–Crafts acylation of anisole with acetic anhydride. The catalytic activity of these materials was compared to other conventional acidic sulfonic heterogeneous catalysts, such as commercial Nafion-SAC-13 and Amberlyst-15. The catalytic performance of MOF materials was significantly dependent on their textural properties and the availability of sulphonic acid groups. MIL-101-SO3H material displayed a remarkable anisole conversion and specific activity per sulfonic acid centre due to its open structure and multimodal pore size distribution. The inherent properties of MIL-101-SO3H material allowed a more sustainable catalyst regeneration than those used for conventional heterogeneous catalysts due to the deposition of reagents and products, in particular poly-acetylated compounds. MIL-101-SO3H proved an easy recovery and reusability in successive runs without any loss of activity. These promising results evidenced the potential of MIL-101-SO3H as an alternative catalyst for acid-catalyzed reactions.

Synthesis and Characterization of Polystyrene Sulfonic Acid from Expanded Polystyrene Foam as a Catalyst in the Synthesis of Triacetin

In Indonesia, the composition of waste has gradually changed over time. To reduce expanded polystyrene (EPS) foam waste, we converted it into a heterogeneous acid catalyst, namely Polystyrene Sulfonic Acid (PSSA). The catalyst was then used in an esterification reaction to generate triacetin. In this research, the synthesis of PSSA was performed using a sulfonation reaction with silver sulfate (Ag2SO4) as the catalyst. Based on FTIR analysis, the sulfonation reaction was successful. The use of 0.5% and 1% catalysts led to a significant increase in the degree of sulfonation of PSSA, while there was a relatively constant increase when using 1.5–2.5% catalysts. The highest degree of sulfonation (78.63%) was achieved when the reaction was performed using 2% Ag2SO4 catalyst for 25 min. The PSSA with the highest degree of sulfonation was characterized using X-Ray Diffraction (XRD), SEM-EDX, and BET-BJH. This PSSA had a semi-crystalline structure with a crystallinity of 73.83%, a particle size of 1.75 nm, mesoporous pores with a radius of 16.984 Å, and a sulfur content of 15% (% mass).

Biodiesel production from wastewater sludge using exchange resins as heterogeneous acid catalyst: Catalyst selection and sludge pre-treatments

Three different ion-exchange resins (Amberlyst 15, 36 and IR120) were used as heterogeneous catalysts for the transesterification of the secondary sludge lipids. Catalyst performance was evaluated based on the biodiesel yield and quality; the best biodiesel yield, with the best properties was obtained with Amberlyst IR120. Microwaves (MW) and ultrasounds (US) were studied as a pre-treatment step to increase lipid extraction. US treatment shows the highest biodiesel yield, providing a biodiesel that fulfils the current regulations. The sludge particle size effect was also studied obtaining the best results using the smallest one. However, in these conditions, ultrasound damage the lipids, decreasing the biodiesel yield. Temperature and catalyst/sludge ratio have been optimized. The maximum biodiesel yield (32.9% FAMEs/lipids) was obtained with Amberlyst IR120, catalyst/sludge ratio 1:2, MeOH/sludge ratio 33:1, 120 °C, 21 h reaction time and US as pre-treatment. The catalyst was also reused for six times under the optimal reaction conditions with negligible catalytic activity loss.

Synthesis and Characterization of Heterogeneous Solid Acid Catalyst from Alstonia scolaris Stalks for Biodiesel Production using Waste Cooking Oil

Background: Waste biomass derived reusable heterogeneous acid based catalysts are more suitable to overcome the problems associated with homogeneous catalysts. The use of agricultural biomass as catalyst for transesterification process is more economical and it reduces the overall production cost of biodiesel. The identification of an appropriate suitable catalyst for effective transesterification will be a landmark in biofuel sector Objective: In the present investigation, waste wood biomass was used to prepare a low cost sulfonated solid acid catalyst for the production of biodiesel using waste cooking oil. Methods: The pretreated wood biomass was first calcined then sulfonated with H2SO4. The catalyst was characterized by various analyses such as, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction (XRD). The central composite design (CCD) based response surface methodology (RSM) was applied to study the influence of individual process variables such as temperature, catalyst load, methanol to oil molar ration and reaction time on biodiesel yield. Results: The obtained optimized conditions are as follows: temperature (165 ˚C), catalyst loading (1.625 wt%), methanol to oil molar ratio (15:1) and reaction time (143 min) with a maximum biodiesel yield of 95 %. The Gas chromatographymass spectrometry (GC-MS) analysis of biodiesel produced from waste cooking oil was showed that it has a mixture of both monounsaturated and saturated methyl esters. Conclusion: Thus the waste wood biomass derived heterogeneous catalyst for the transesterification process of waste cooking oil can be applied for sustainable biodiesel production by adding an additional value for the waste materials and also eliminating the disposable problem of waste oils.

Brønsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols

Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ∼1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ∼100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.

Esterification of Khaya senegalensis seed oil with a solid heterogeneous acid catalyst: Modeling, optimization, kinetic and thermodynamic studies

The current study investigated the esterification of Khaya senegalensis seed oil (KSSO) with a high free fatty acid (FFA) using ferric sulfate (Fe 2 (SO 4 ) 3 ) as a solid heterogeneous acid catalyst. Taguchi design approach was applied in modeling and optimizing the input variables to obtain the minimum %FFA for the KSSO esterification process. Besides modeling and optimization, the kinetic and thermodynamic studies of the process were carried out to obtain pertinent data required for reactor design. The optimum values with the minimum %FFA (0.49) for the esterification process are a temperature of 60 °C, methanol-to-KSSO ratio of 15:1, ferric sulfate dosage of 9 wt%, and time of 60 min. The reaction of the triglycerides in the KSSO with methanol showed that it followed first-order kinetics. The pre-exponential factor ( A ), activation energy ( E a ), and reaction rate constant ( k ) for the reaction are 37.73 min -1 , 18.11 kJ/mol, and 0.0554 min -1 , respectively, at a temperature of 60 °C, indicating that the esterification process proceeded at a fast rate. The thermodynamic properties determined for the process are Δ S § (entropy), Δ H § (enthalpy), and Δ G § (Gibbs free energy) of activation with respective values of – 0.205 kJ/mol.K, 15.34 kJ/mol, and 83.54 kJ/mol, confirming the endergonic, endothermic, and non-spontaneous nature of the reaction. Thus, the determination of key process conditions with the kinetic and thermodynamic properties of the KSSO esterification process could aid the use of the oil as a viable feedstock for biodiesel synthesis and reactor design for industrial applications. • High free fatty acid Khaya oil was esterified with methanol to < 1%. • Ferric sulfate served as a solid heterogeneous acid catalyst for the esterification. • Minimum %FFA of 0.49 was obtained with the optimum values predicted by the model. • The esterification process followed pseudo first-order kinetics. • The nature of the reaction was endergonic, endothermic, and non-spontaneous.

Inhibition by Water during Heterogeneous Brønsted Acid Catalysis by Three-Dimensional Crystalline Organic Salts

A new self-assembled and self-healing class of metal free, recyclable, heterogeneous Bronsted acid catalysts has been developed by the protonation of aniline derivatives (tetrakis(4-aminophenyl)met...

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

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

Palm fatty acid distillate-based biodiesel with sulfonated chicken and cow bone catalyst

The depletion of fossil fuel and the distressing environmental condition originated from the massive consumption of nonrenewable energy has urge towards the seeking for a cleaner and renewable energy source. Numerous forms of renewable energy have been developed over the past few decades and biodiesel emerged as one of the prospective candidate. The demand for global biodiesel production has been steadily growing. In line with that, researches around the world are racing towards making biodiesel technology more sustainable and economically viable process. In this investigation, the development of biodiesel from palm fatty acid distillate via the esterification process using sulfonated chicken bone and cow bone catalyst assisted by microwave irradiation was conducted (replacing the conventional oven heating). Subsequently the bones were calcined at 900 °C and then sulfonated. The synthesized catalysts were characterized using X-Ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, Brunauer–Emmett–Teller and temperature-programmed desorption. The reaction was prepared with a catalyst loading of 1 % to 6 % and a molar ratio of 2:1 to 25:1 for methanol:PFAD, while the reaction time was conducted for 30–240 mins and the reaction temperature was kept at 70 °C for each experiment set. In addition, a catalyst loading of 5 wt% and molar ratio of 20:1 for methanol:PFAD with the reaction time of 180 mins and reaction temperature of 70 °C were used as optimal condition parameters. For the sulfonated chicken bone catalyst, the percentage yield and conversion of biodiesel were 80.8% and 98.2%, respectively. In contrast, the percentage yield and conversion rate reached to 81.5% and 97.7%, respectively, for the the sulfonated cow bone catalyst. The biodiesel properties obtained were in accordance with ASTM standards. The percentage of FAME content was determined utilizing gas chromatography. The bones have been shown to be appropriate sustainable precursors for the synthesis of a novel, highly effective heterogeneous acid catalyst for biodiesel development.

Mesoporous tin phosphate as an effective catalyst for fast cyclodehydration of bio-based citral into p-cymene

Effective synthesis of aromatic compounds from renewable biomass is highly important yet challenging. p-Cymene is an attractive aromatic compound with various promising applications in the manufacture of fine chemicals. In this study, a novel and effective catalytic system based on mesoporous tin phosphate (M-SnPO) with Lewis-Brønsted dual acidity was developed for the fast synthesis of p-cymene from the cyclodehydration of bio-based citral. Up to 78.5% yield of p-cymene was achieved from the cyclodehydration of citral at 180 °C within only 0.5 h, superior to the results reported for benchmark homogeneous acid catalysts. Characterization of as-prepared M-SnPO catalyst via various techniques indicates that the synergic effect of Lewis and Brønsted acidic sites, large pore-sized structure, and high surface area are responsible for its remarkable catalytic performance. In addition, the effectiveness of the M-SnPO catalyst could be almost sustained over multiple cycles without significant loss. The work herein is the first example of developing a Lewis-Brønsted dual acidic heterogeneous catalyst for the fast synthesis of p-cymene from the cyclodehydration of citral.

A Review on the Efficient Catalysts for Algae Transesterification to Biodiesel

The depletion of fossil fuel resources and increasing environmental pollution led to a trend for using alternative, clean, green, and sustainable fuel and energy resources. To attain this aim, using biomass as an alternative resource for diesel production has been a hotspot among researchers. Biodiesel has several advantages, such as being lower toxic and more renewable, and eco-friendlier than diesel from fossil fuel resources. Several edible and non-edible bio-sources were used for the production of biodiesel from the transesterification process. Algal oil as a non-edible source is considered an abundant, low cost and green substrate for biodiesel production. Various factors such as reaction conditions and the type of catalyst affect the biodiesel production process. Different catalytic systems such as basic and acidic homogeneous and heterogeneous catalysts and biocatalysts were introduced for the process in the literature, and each proposed catalyst has its own advantages and disadvantages. For instance, in spite of the lower cost and better mass transfer of base and acid homogeneous catalysts, reaction system corrosion, non-reusability, and soap formation are serious challenges of these catalysts at an industrial scale. On the other hand, acid and base heterogenous catalysts overcame the issues of corrosion and recovery, but some matters such as mass transfer limitation, high cost, and weak performance in catalyzing both esterification of FFAs and transesterification of lipids must be taken into account. In addition, bio-catalysis as a high-cost process led to a purer product formation with less side reaction. Therefore, several significant factors should be considered for transesterification catalysts such as availability, cost, reusability, stability, mass transfer, and the possibility to manage both the transesterification of triglycerides and the esterification of FFAs, selecting a catalyst with predominant pros is viable. Here, a review of the biodiesel production from algal biomass focusing on the efficient catalyst of the process is presented.

Hydrolysis of semi‐industrial aqueous extracted xylan from birch (Betula pendula) employing commercial catalysts: kinetics and modelling

AbstractBACKGROUNDAcidic hydrolysis of a birch (Betula pendula) xylan produced by a novel semi‐industrial‐scale aqueous‐based and highly sustainable method was studied in a batch reactor. Five commercial acidic heterogeneous catalysts were screened and significant differences in their performance were observed. Dowex 50WX2‐100 was selected for further studies and the influence of the reaction parameters, including stirring speed, pH (0.5–1.5), temperature (115–145 °C) and catalyst particle size (50–400 mesh) were studied. The goal was to maximize xylose yield by balancing between the kinetics of hydrolysis and the undesired degradation of monosaccharides.RESULTSThe results show that the maximum achieved yield of xylose was 76%, but higher yields were hindered by the consecutive dehydration of sugars. It was also observed that the hydrolysis and dehydration reactions do not follow the same dependence on the experimental parameters, which leaves room for optimization of the yield. A kinetic model was developed based on the data, which takes into account the consecutive reaction pathway and the influence of the experimental conditions, and a very good fit of the model to the experimental data was achieved. An activation energy of 119 and 88 kJ mol–1 was obtained for the hydrolysis and dehydration steps, respectively.CONCLUSIONHydrolysis results of this novel, well‐characterized hemicellulose extract have not been published previously, and they contribute significantly to the understanding of the hydrolysis and dehydration of real feedstock, instead of highly purified and typically very deacetylated model compounds with different characteristics and behaviour in hydrolysis. © 2021 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Trends in Widely Used Catalysts for Fatty Acid Methyl Esters (FAME) Production: A Review

The effective transesterification process to produce fatty acid methyl esters (FAME) requires the use of low-cost, less corrosive, environmentally friendly and effective catalysts. Currently, worldwide biodiesel production revolves around the use of alkaline and acidic catalysts employed in heterogeneous and homogeneous phases. Homogeneous catalysts (soluble catalysts) for FAME production have been widespread for a while, but solid catalysts (heterogeneous catalysts) are a newer development for FAME production. The rate of reaction is much increased when homogeneous basic catalysts are used, but the main drawback is the cost of the process which arises due to the separation of catalysts from the reaction media after product formation. A promising field for catalytic biodiesel production is the use of heteropoly acids (HPAs) and polyoxometalate compounds. The flexibility of their structures and super acidic properties can be enhanced by incorporation of polyoxometalate anions into the complex proton acids. This pseudo liquid phase makes it possible for nearly all mobile protons to take part in the catalysis process. Carbonaceous materials which are obtained after sulfonation show promising catalytic activity towards the transesterification process. Another promising heterogeneous acid catalyst used for FAME production is vanadium phosphate. Furthermore, biocatalysts are receiving attention for large-scale FAME production in which lipase is the most common one used successfully This review critically describes the most important homogeneous and heterogeneous catalysts used in the current FAME production, with future directions for their use.