Study on the solid acid catalysts in biodiesel production from high acid value oil

A comprehensive review on nanocatalysts and nanobiocatalysts for biodiesel production in Indonesia, Malaysia, Brazil and USA

Biodiesel is an alternative to fossil-derived diesel with similar properties and several environmental benefits. Biodiesel production using conventional catalysts such as homogeneous, heterogeneous, or enzymatic catalysts faces a problem regarding catalysts deactivation after repeated reaction cycles. Heterogeneous nanocatalysts and nanobiocatalysts (enzymes) have shown better advantages due to higher activity, recyclability, larger surface area, and improved active sites. Despite a large number of studies on this subject, there are still challenges regarding its stability, recyclability, and scale-up processes for biodiesel production. Therefore, the purpose of this study is to review current modifications and role of nanocatalysts and nanobiocatalysts and also to observe effect of various parameters on biodiesel production. Nanocatalysts and nanobiocatalysts demonstrate long-term stability due to strong Brønsted-Lewis acidity, larger active spots and better accessibility leading to enhancethe biodiesel production. Incorporation of metal supporting positively contributes to shorten the reaction time and enhance the longer reusability. Furthermore, proper operating parameters play a vital role to optimize the biodiesel productivity in the commercial scale process due to higher conversion, yield and selectivity with the lower process cost. This article also analyses the relationship between different types of feedstocks towards the quality and quantity of biodiesel production. Crude palm oil is convinced as the most prospective and promising feedstock due to massive production, low cost, and easily available. It also evaluates key factors and technologies for biodiesel production in Indonesia, Malaysia, Brazil, and the USA as the biggest biodiesel production supply.

A review of sustainable biodiesel production using biomass derived heterogeneous catalysts

The production of biodiesel through chemical production processes of transesterification reaction depends on suitable catalysts to hasten the chemical reactions. Therefore, the initial selection of catalysts is critical although it is also dependent on the quantity of free fatty acids in a given sample of oil. Earlier forms of biodiesel production processes relied on homogeneous catalysts, which have undesirable effects such as toxicity, high flammability, corrosion, by-products such as soap and glycerol, and high wastewater. Heterogeneous catalysts overcome most of these problems. Recent developments involve novel approaches using biomass and bio-waste resource derived heterogeneous catalysts. These catalysts are renewable, non-toxic, reusable, offer high catalytic activity and stability in both acidic and base conditions, and show high tolerance properties to water. This review work critically reviews biomass-based heterogeneous catalysts, especially those utilized in sustainable production of biofuel and biodiesel. This review examines the sustainability of these catalysts in literature in terms of small-scale laboratory and industrial applications in large-scale biodiesel and biofuel production. Furthermore, this work will critically review natural heterogeneous biomass waste and bio-waste catalysts in relation to upcoming nanotechnologies. Finally, this work will review the gaps identified in the literature for heterogeneous catalysts derived from biomass and other biocatalysts with a view to identifying future prospects for heterogeneous catalysts.

Esterification of residual palm oil using solid acid catalyst derived from rice husk

In this study, carbon-silica based acid catalysts derived from rice husks (RH) were successfully synthesised using microwave (MW) technology. The results showed that MW sulphonation produced Sulphur (S) content of 17.2-18.5 times higher than in raw RH. Fourier-transform Infrared Spectroscopy (FTIR) showed peak at 1035 cm^-1 which corresponded to O˭S˭O stretching of sulphonic (-SO₃H) group. XRD showed sulfonated RH catalysts (SRHCs) have amorphous structure, and through SEM, broadening of the RH voids and also formation of pores is observed. RH600 had the highest surface area of 14.52 m²/g. SRHCs showed high catalytic activity for esterification of oleic acid with methanol with RH600 had the highest initial formation rate (6.33 mmolL^-1min^-1) and yield (97%). The reusability of the catalyst showed gradually dropped yield of product for every recycle, which might be due to leaching of -SO₃H. Finally, esterification of oil recovered from palm oil mill effluent (POME) with methanol achieved a conversion of 87.3% free fatty acids (FFA) into fatty acid methyl esters (FAME).

Biodiesel production from rapeseed oil and low free fatty acid waste cooking oil using a cesium modified natural phosphate catalyst

The present study focuses on the catalytic activity of cesium modified natural phosphate in biodiesel production from rapeseed oil and low free fatty acids (FFA) used in cooking oil. The catalyst was prepared by impregnation of cesium chloride (CsCl) on the natural phosphate followed by calcination up to 800 °C. The phosphate based catalyst was thermally, structurally, morphologically, and texturally characterized in order to determinate the relationship between its physicochemical properties and its catalytic activity. The chosen catalyst was demonstrated to be an active catalyst for the transesterification of rapeseed oil achieving a biodiesel yield of 99.55% under suitable reaction conditions: a methanol to oil molar ratio of 12 : 1, reaction temperature of 70 °C, catalyst amount of 4 wt% based on oil weight and reaction time of 6 h. Results from low FFA waste cooking oil transesterification indicated that a methyl esters yield of 99.52% could be obtained. Furthermore, results from esterification/transesterification of acidified rapeseed oil indicate that a yield of 93% may be obtained, thus giving rise to a potential application in 2^nd generation biodiesel production from low acidic oils. Some important physicochemical properties of the obtained biodiesel were evaluated and compared with the EN14214 and ASTM D-6751 standards for biodiesel specifications.

Cesium modified natural phosphate was investigated as a catalyst in biodiesel production from rapeseed oil and low free fatty acids used in cooking oil.

Synthesis and Structural Characterization of Biofuel From Cocklebur sp., Using Zinc Oxide Nano-Particle: A Novel Energy Crop for Bioenergy Industry

This study is reporting the biofuel synthesis and characterization from the novel non-edible feedstock cocklebur seeds oil. The Cocklebur crop seeds oil was studied as a potential source for biofuel production based on the chemical, structural and fuel properties analysis. The oil expression and FFAs content in cocklebur crop was reported 37.2% and 0.47 gram KOH/g, using soxhlet apparatus and acid base titration method, respectively. The maximum conversion and yield of the cocklebur crop seeds non-edible oil to biofuel was pursued 93.33%, using transesterification process. The optimum protocol for maximum conversion yield was adjusted: 1:7 oil-methanol molar ratios, ZnO nano-particle concentration 0.2 gm (w/w), reaction temperature 60°C, and reaction time 45 min, respectively. ZnO nano-particle was prepared by a modified sol-gel method, using gelatin and the particle was XRD, TEM, XPS, and UV-vis spectroscopies. Qualitatively, the cocklebur crop synthesized biofuel was quantified and structurally characterized by GC/MS, FT-IR, NMR, and AAS spectroscopies. Quantitatively, the fuel properties of cocklebur crop biofuel was analyzed and compared with the international ASTM and EN standards.

Keggin-structure heteropolyacid supported on alumina to be used in trans/esterification of high-acid feedstocks

Heteropolyacids (HPA) with Keggin structures, such as H₃PMo₁₂O₄₀ (H₃PMo), have been described as efficient catalysts in trans/esterification reactions due to their tolerance to water and free fatty acids contents, with particularly well-suited characteristics of high proton mobility and stability. The versatile array of HPA is considerably increased when such catalysts are supported onto solid matrices. In this sense, Al₂O₃ was assessed as support for H₃PMo to be used in trans/esterification reactions to produce biodiesel from high-acid feedstocks. The catalyst structure was characterized and applied on trans/esterification reaction of acid oils using ethanol as acyl acceptor. A face centered composite design was employed to conduct the experimental design and results analysis, taking macaw palm oil as study model. The process achieved an optimum level of 99.8% ester content and 4.1 mm² s⁻¹ viscosity under the following reaction conditions: 190 °C reaction temperature, 50 : 1 ethanol-to-oil molar ratio and 13.0% catalyst concentration. Other tested feedstocks (fungal single cell oil and residual frying oil) were also tested promoting satisfactory results, though the parameters were found to be slightly outside the limits set by the USA (ASTM D6715) standard. The H₃PMo/Al₂O₃ catalyst presented good regeneration and can be reused for up to four reaction cycles and requires lower ethanol-to-oil ratio, temperature, and catalyst concentration in comparison with other data from the literature.

Heteropolyacids (HPA) with Keggin structures, such as H₃PMo₁₂O₄₀ (H₃PMo), have been described as efficient catalysts in trans/esterifications of high-acid feedstocks due to their tolerance to water and free fatty acids contents.

Catalyst and Process Design for the Continuous Manufacture of Rare Sugar Alcohols by Epimerization-Hydrogenation of Aldoses

Sugar alcohols are applied in the food, pharmaceutical, polymer, and fuel industries and are commonly obtained by reduction of the corresponding saccharides. In view of the rarity of some sugar substrates, epimerization of a readily available monosaccharide has been proposed as a solution, but an efficient catalytic system has not yet been identified. Herein, a molybdenum heteropolyacid-based catalyst is developed to transform glucose, arabinose, and xylose into less-abundant mannose, ribose, and lyxose, respectively. Adsorption of molybdic acid onto activated carbon followed by ion exchange to the cesium form limits leaching of the active phase, which greatly improves the catalyst stability over 24 h on stream. The hydrogenation of mixtures of epimers is studied over ruthenium catalysts, and it is found that the precursor to the desired polyol is advantageously converted with faster kinetics. This is explained by density functional theory on the basis of its more favorable adsorption on the metal surface and the lower energy barrier for the addition of a hydrogen atom to the primary carbon atom. Finally, different designs for a continuous process for the conversion of glucose into mannitol are studied, and it is uncovered that two reactors in series with one containing the epimerization catalyst and the other containing a mixture of the epimerization and hydrogenation catalysts increases the mannitol/sorbitol ratio to 1.5 from 1 for a single mixed-bed reactor. This opens a prospective route to the efficient valorization of renewables to added-value chemicals.

Green biodiesel production from waste cooking oil using an environmentally benign acid catalyst

The application of an environmentally benign sulfonated carbon microsphere catalyst for biodiesel production from waste cooking oil was investigated. This catalyst was prepared by the sequential hydrothermal carbonization and sulfonation of xylose. The morphology, surface area, and acid properties were analyzed. The surface area and acidity of the catalyst were 86m(2)/g and 1.38mmol/g, respectively. In addition, the presence of sulfonic acid on the carbon surface was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The catalytic activity was tested for biodiesel production from waste cooking oil via a two-step reaction to overcome reaction equilibrium. The highest biodiesel yield (89.6%) was obtained at a reaction temperature of 110°C, duration time of 4h, and catalyst loading of 10wt% under elevated pressure 2.3bar and 1.4bar for first and second step, respectively. The reusability of the catalyst was investigated and showed that the biodiesel yield decreased by 9% with each cycle; however, this catalyst is still of interest because it is an example of green chemistry, is nontoxic, and makes use of xylose waste.

Production of biodiesel from Vietnamese Jatropha curcas oil by a co-solvent method

Biodiesel fuels (BDFs) was successfully produced from Vietnamese Jatropha curcas oil with high content of free fatty acids (FFAs) in two stages. In the first stage, the esterification process was carried out with the optimal conditions as follows; a methanol-to-FFAs molar ratio of 6:1, 1 wt% H2SO4, at a temperature of 65 °C, and using 30% (wt/wt) acetonitrile as co-solvent. This step reduced the concentration of FFAs in the reaction mixture from 15.93 to 2 wt% in 60 min. In the second stage, the transesterification process generated fatty acid methyl esters (FAMEs) with 99% efficiency was performed in 30 min with the optimal conditions as follows; a methanol-to-oil molar ratio of 6:1, 1 wt% KOH, at a temperature of 40 °C, and 20% (wt/wt) acetone as co-solvent. The produced biodiesel quality meets the standards JIS K2390 and EN 14214 regarding FAME yield, FFAs and water contents.

Heterogeneous catalysis for sustainable biodiesel productionviaesterification and transesterification

Low temperature catalytic conversion of triglycerides and fatty acids sourced from renewable feedstocks represents a key enabling technology for the sustainable production of biodiesel through energy efficient, intensified processes.