KOH/bentonite catalysts for transesterification of palm oil to biodiesel

A potential application of KOH/bentonite as a catalyst for biodiesel production was studied. A series of KOH/bentonite catalysts was prepared by impregnation of bentonite from Pacitan with potassium hydroxide. The ratios between KOH and bentonite were 1:20, 1:10, 1:5, 1:4, 1:3, and 1:2. The characterization of KOH/bentonite and natural bentonite was conducted by nitrogen adsorption and XRD analysis. The effects of various reaction variables on the yield of biodiesel were investigated. The highest yield of biodiesel over KOH/bentonite catalyst was 90.70 ± 2.47%. It was obtained at KOH/bentonite 1:4, reaction time of 3 h, 3% catalyst, methanol to oil ratio of 6, and the reaction temperature at 60 °C.     

Transesterification of castor oil assisted by microwave irradiation

Microwave assisted transesterification of castor bean oil was carried out in the presence of methanol or ethanol, using a molar ratio alcohol/castor bean oil of 6:1, and 10% w/w of acidic silica gel or basic alumina (in relation to the oil mass) as catalyst. Under acid catalysis, the reaction occurred with satisfactory yields using H₂SO₄ immobilized in SiO₂, methanol under conventional conditions (60 °C for 3 h) as well as using microwave irradiation for 30 min. The best results were obtained under basic conditions (Al₂O₃/50% KOH) using methanol and conventional (60 °C, stirring, 1 h) or microwave conditions (5 min). In comparison with conventional heating, the catalyzed alcoholysis assisted by microwaves is much faster and leads to higher yields of the desired fatty esters.     

Synthesis of economically viable biodiesel from waste frying oils (WFO)

In present communication, waste frying oil (WFO) has been used as a feedstock for biodiesel synthesis. WFO, procured from a local Indian restaurant possessed an acid value of 0.84 mg KOH/g, which is low enough for single step transesterification reaction. Biodiesel (fatty acid methyl esters) was washed after transesterification reaction and the yield got lowered substantially (from 96% to 86.36%) after water washing owing to loss of esters. 30:100 vol% (methanol to oil), 0.6 wt% NaOCH₃, 60°C temperature and 600 rpm agitation in 1 h reaction time was found to be optimum for transesterification reaction. ¹H NMR spectrum showed a high conversion (95.19%) of fatty acids in WFO to biodiesel in 2 h reaction time. Almost complete conversion (99.68%) was attained in 2 h reaction time. © 2011 Canadian Society for Chemical Engineering     

Optimization of process conditions using response surface methodology for the microwave-assisted transesterification of Jatropha oil with KOH impregnated CaO as catalyst

A transesterification reaction of Jatropha curcas oil with methanol in the presence of KOH impregnated CaO catalyst was performed in a simple continuous process. The process variables such as methanol/oil molar ratio (X₁), amount of catalyst (X₂) and total reaction time (X₃) were optimized through response surface methodology, using the Box–Behnken model. Within the range of the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and total reaction time were found to be 8.42, 3.17% and 67.9 min, respectively. The results showed that the amount of catalyst and total reaction time have significant effects on the transesterification reaction. For the product to be accepted as a biodiesel fuel, its purity must be above 96.5% of alkyl esters. Based on the optimum condition, the predicted biodiesel conversion was 97.6% while the actual experimental value was 97.1%. The above mentioned results demonstrated that the response surface methodology (RSM) based on Box–Behnken model can well predict the optimum condition for the biodiesel production.     

A hybrid feedstock for a very efficient preparation of biodiesel

Biodiesel has been synthesized from karanja, mahua and hybrid {karanja and mahua (50:50 v/v)} feedstocks. A high yield in the range of 95-97% was obtained with all the three feedstocks. Conversion of vegetable oil to fatty acid methyl esters was found to be 98.6%, 95.71% and 94% for karanja, mahua and hybrid feedstocks respectively. The optimized reaction parameters were found to be 6:1 (methanol to oil) molar ratio, H₂SO₄ (1.5% v/v), at 55 ± 0.5 °C for 1 h during acid esterification for the three feedstocks. During alkaline transesterification, a molar ratio of 8:1 (methanol to oil), 0.8 wt.% KOH (wt/wt) at 55 ± 0.5 °C for 1 h was found to be optimum to achieve high yield for karanja oil. For mahua oil and the hybrid feedstock, 6:1 (methanol to oil) molar ratio, 0.75 (w/w) KOH at 55 ± 0.5 °C for 1 h was optimum for alkaline transesterification to obtain a high yield. High yield and conversion from hybrid feedstock during transesterification reaction was an indication that the reaction was not selective for any particular oil. ¹H NMR has been used for the determination of conversion of the feedstock to biodiesel.     

Transesterification of Rapeseed Oil for Synthesizing Biodiesel by K/KOH/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> as Heterogeneous Base Catalyst

The heterogeneous base catalyst, γ-Al₂O₃ loaded with KOH and K (K/KOH/γ-Al₂O₃) was first prepared and used in the transesterification of rapeseed oil with methanol to produce biodiesel. The prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller method, infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that when γ-Al₂O₃ is loaded with KOH and K, the Al–O–K species is produced, resulting in an increase in the catalytic activity. The impacts of catalyst preparation conditions on the catalytic activities of K/KOH/γ-Al₂O₃ were investigated. The results demonstrate that the catalyst K/KOH/γ-Al₂O₃ has high catalytic activity when the added amounts of KOH and K are 20 and 7.5 wt% respectively. The transesterification of rapeseed oil to biodiesel with the prepared heterogeneous base catalyst was optimized. It was found that the yield of biodiesel can reach as high as 84.52% after 1 h reaction at 60°C, with a 9:1 molar ratio of methanol to oil, a catalyst amount of 4 wt%, and a stirring rate of 270 g.     

Electrochemical reduction of carbon dioxide to ethylene at a copper electrode in methanol using potassium hydroxide and rubidium hydroxide supporting electrolytes

The electrochemical reduction of CO₂ with a Cu electrode was investigated in methanol using potassium hydroxide and rubidium hydroxide supporting salts. The main products from CO₂ were methane, ethylene, carbon monoxide and formic acid. The maximum current efficiency for ethylene was of 37.5%, at −4.0 V versus Ag/AgCl, saturated KCl in KOH/methanol. The typical ratios of current efficiency for ethylene/methane, r_f(C₂H₄)/r_f(CH₄), were 2.3 and 6.7, in KOH/methanol and RbOH/methanol-based electrolytes, respectively. In KOH/methanol, the efficiency of hydrogen formation, a competing reaction of CO₂ reduction, was depressed to below 3.3%. On the basis of this work, the high efficiency electrochemical CO₂-to-ethylene conversion method appears to be achieved. Future work to advance this technology may include the use of solar energy as the electric energy source. This research can contribute to the large-scale manufacturing of fuel gases from readily available and inexpensive raw materials, CO₂-saturated methanol from industrial absorbers (the Rectisol process).     

Biodiesel synthesis: A study of the triglyceride methanolysis reaction with alkaline catalysts

The rates of soybean oil methanolysis under NaOCH₃, KOCH₃, NaOH and KOH catalysis were determined at 30.0, 40.0, 50.0 and 60.0 °C using a refractometric method for online monitoring of this reaction. The influences of the metallic cations and anions on the catalysis were studied. Potassium promotes faster reactions than sodium. For the reactions catalyzed by hydroxides, the rate constants are less sensitive to temperature than those catalyzed by methoxides. The proposed reaction mechanism was based on the formation of ionic pairs at the interface of the methanol and oil phases and in the methanol phase.     

Biodiesel production from waste cooking oil in a microtube reactor

Waste cooking oil (WCO) was used to produce biodiesel in a microtube reactor. First, the acid value of the WCO was reduced from 3.96 mg KOH/g to less than 1 mg KOH/g via acid catalyzed esterification. The effects of the methanol-to-WCO molar ratio (4.5:1–18:1), the H₂SO₄ concentration (0.5–2 wt.%), reaction temperature (55–70 °C), and reaction time (5–20 s) were studied. The optimal conditions were 9:1 methanol-to-WCO molar ratio, 1 wt.% H₂SO₄, 65 °C and 5 s of reaction time. Triglycerides in the product from the first step were transesterified with methanol and alkaline catalyst. Methyl ester content of the biodiesel was 91.76%.     

Lewis acid-catalyzed transesterification and esterification of high free fatty acid oil in subcritical methanol

Lewis acid catalysts are active for both esterification and transesterification, but the reaction is very slow due to mass-transfer limitations between methanol and oil phase. Because oil, FFA and Lewis acid catalysts are all soluble in the subcritical methanol phase, the esterification and transesterification will be enhanced when they are carried out under subcritical conditions. In this work, the esterification and transesterification of high FFA oil to biodiesel via Lewis acid catalysts such as Pb(OOCCH₃)₂, Cd(OOCCH₃)₂ and Zn(OOCCH₃)₂ were carried out in the subcritical methanol phase (2 MPa, 180°C, reaction time 30 min). The results show that the esterification conversion reaches 79.8-96.4% with Palmitic acid as feedstock, and the transesterification conversion reaches 56.8-73.4% with soybean oil as feedstock. With the mixture of Soybean oil and Palmitic acid (FFA content of 20.3 wt%) as feedstock, the content of fatty acid methyl esters (FAME) in products reaches 67.3-83.4%.     

Eco-friendly Pretreatment of Oil with High Free Fatty Acid Content Using a Sulfamic Acid/Ethanol System

In recent years, sulfamic acid (SA, NH₂SO₃H) has emerged as a novel green catalyst for organic synthesis because of several advantages, including its non‐volatility, non‐hygroscopicity, non‐corrosivity, and low cost. This work reports the use of sulfamic acid as a catalyst in the pretreatment of oil with a high content of free fatty acids (10 and 20 % FFA) in ethanol or methanol. The process (esterification reaction) used in the pretreatment of the oil was carried out under a variety of conditions, initial fatty acid content, temperature, type of alcohol, and % catalyst. The experiments using an NH₂SO₃H/ethanol system resulted in a high fatty acid ethyl ester conversion, 88.53 % (±0.95) from an initial acidity of 40 mg KOH/g (20 % FFA), using 8 % NH₂SO₃H as the catalyst. According to the results, the methodology using sulfamic acid and ethanol demonstrated elevated potential for a environmentally‐friendly means of biodiesel production.     

Purification Process,Physicochemical Properties,and Fatty Acid Composition of Black Soldier Fly (Hermetia illucens Linnaeus) Larvae Oil

This study presented a refining process and reported on fatty acid composition and the physicochemical properties of the oil from black soldier fly larvae (BSFL). Crude larvae oil was purified through four steps consisting of degumming, neutralization, bleaching, and deodorization. Optimum degumming conditions that give the highest phospholipid weight and oil consisted of water concentration of 7% (v/v), followed by addition of H₂SO₄ at a concentration of 0.5% (v/v). Optimum conditions for saponification that maximize saponification value and free fatty acid (FFA) value were 0.4 mg NaOH/100 g oil, 1 hour, and 80 °C of NaOH quantity, reaction time, and temperature, respectively. The oil was then dehydrated using 10 mg Na₂SO₄/g oil. The bleaching process that gives maximum oil yield consisted of activated carbon at concentration of 5% (w/w), followed by centrifugation at a speed of 5000 rpm (radius = 86 mm) for 30 min. The contents of lauric acid, linoleic acid, and linolenic acid in purified oil were 28.8%, 11.1%, and 0.4%, respectively. Physicochemical properties of the refined oil included viscosity of 96 ± 0.14 cP (measured at 20 °C), FFA value of 0.45 ± 0.017%, acid value of 0.9 ± 0.043 mg KOH g⁻¹, saponification value of 215.78 mg KOH g⁻¹, iodine value of 53.7 gI₂/100 g, and peroxide index of 133 mEq kg⁻¹.     

Reduction of high content of free fatty acid in sludge palm oil via acid catalyst for biodiesel production

In this study, sulphuric acid (H₂SO₄) was used in the pretreatment of sludge palm oil for biodiesel production by an esterification process, followed by the basic catalyzed transesterification process. The purpose of the pretreatment process was to reduce the free fatty acids (FFA) content from high content FFA (> 23%) of sludge palm oil (SPO) to a minimum level for biodiesel production (> 2%). An acid catalyzed esterification process was carried out to evaluate the low content of FFA in the treated SPO with the effects of other parameters such as molar ratio of methanol to SPO (6:1-14:1), temperature (40-80 °C), reaction time (30-120 min) and stirrer speed (200-800 rpm). The results showed that the FFA of SPO was reduced from 23.2% to less than 2% FFA using 0.75% wt/wt of sulphuric acid with the molar ratio of methanol to oil of 8:1 for 60 min reaction time at 60 °C. The results on the transesterification with esterified SPO showed that the yield (ester) of biodiesel was 83.72% with the process conditions of molar ratio of methanol to SPO 10:1, reaction temperature 60 °C, reaction time 60 min, stirrer speed 400 rpm and KOH 1% (wt/wt). The biodiesel produced from the SPO was favorable as compared to the EN 14214 and ASTM D 6751 standard.     

An ideal feedstock, kusum (Schleichera triguga) for preparation of biodiesel: Optimization of parameters

Kusum (Schleichera triguga), a non-edible oil bearing plant has been used as an ideal feedstock for biodiesel development in the present study. Various physical and chemical parameters of the raw oil and the fatty acid methyl esters derived have been tested to confirm its suitability as a biodiesel fuel. The fatty acid component of the oil was tested by gas chromatography. The acid value of the oil was determined by titration and was found to 21.30 mg KOH/g which required two step transesterification. Acid value was brought down by esterification using sulfuric acid (H₂SO₄) as a catalyst. Thereafter, alkaline transesterification was carried out using potassium hydroxide (KOH) as catalyst for conversion of kusum oil to its methyl esters. Various parameters such as molar ratio, amount of catalyst and reaction time were optimized and a high yield (95%) of biodiesel was achieved. The high conversion of the feedstock into esters was confirmed by analysis of the product on gas chromatograph-mass spectrometer (GC-MS). Viscosity and acid value of the product biodiesel were determined and found to be within the limits of ASTM D 6751 specifications. Elemental analysis of biodiesel showed presence of carbon, hydrogen, oxygen and absence of nitrogen and sulfur after purification. Molar ratio of methanol to oil was optimized and found to be 10:1 for acid esterification, and 8:1 for alkaline transesterification. The amounts of H₂SO₄ and KOH, 1% (v/v) and 0.7% (w/w), respectively, were found to be optimum for the reactions. The time duration of 1 h for acid esterification followed by another 1 h for alkaline transesterification at 50 ± 0.5 °C was optimum for synthesis of biodiesel.     

Mineralogical Analysis of Clays in Soils Developed from Basalts in Australia

Clay mineralogical analyses were made of red soils and black soils developed from southern Victoria, Australia. The clays of the black soils are dominantly montmorillonite (39%) and vermiculite (16%) but have an average siliceous allophane content of 17%. The clays of the red soils are dominantly kaolinite and halloysite (26%) and chlorite (30%) but have an average halloysitic allophane content of 21%. Two to eight per cent of mica and quartz occur in both. A longer period of eolian dust accumulation and concurrent weathering and soil development have occurred in the red soils than in the black soils since the last cycle of geological erosion. A simple chemical method was used for the estimation of allophane (amorphous alumina, silica, and iron oxide with water) and kaolinite plus halloysite. After selective dissolution of allophane, free Al(OH)₃, and amorphous SiO₂ during 2.5 min of boiling in 0.5N KOH solution, the residue is subjected to heat treatment at 550°C to dehydroxylate the kaolinite and halloysite. This is followed by another 2.5 min dissolution treatment in 0.5N KOH and a further deferration with dithionite. Some iron-rich montmorillonitesaponite (smectite) and vermiculite are also dehydroxylated on heating and subsequently are partially dissolved in the KOH. The kaolinite and halloysite constituents were then calculated.     

Preparation of bio-fuels by catalytic cracking reaction of vegetable oil sludge

Biofuel production from vegetable oil is potentially a good alternative to conventional fossil derived fuels. Moreover, liquid biofuel offers many environmental benefits since it is free from nitrogen and sulfur compounds. Biofuel can be obtained from biomass (e.g. pyrolysis, gasification) and agricultural sources such as vegetable oil, vegetable oil sludge, rubber seed oil, and soybean oil. One of the most promising sources of biofuel is vegetable oil sludge. This waste is a major byproduct of vegetable oil factories. It consists of triglycerides (61%), free fatty acid (37%) and impurities (2%). The hydrocarbon chains of triglycerides and free fatty acid are mainly made up of C₁₆ (30%) and C₁₈ (36%) hydrocarbons. The others consist of C₁₂-C₁₇ hydrocarbon chains. Transesterification can help in converting vegetable oil sludge into biofuel. The disadvantage of this method is that a large amount of methanol is required. The alternative method for this conversion is catalytic cracking. The objective of this research is to evaluate and compare the pyrolysis process with cracking catalytic reaction of vegetable oil sludge by Micro-activity test MAT 5000 of Zeton-Canada.A ZSM-5/MCM-41 multiporous composite (MC-ZSM-5/MCM-41), was successfully synthesized using silica source extracted from rice husk. The material has the MCM-41 mesoporous structure, and its wall is constructed by ZSM-5 nanozeolite crystals. The porous system of the material includes pores of the following sizes: 5 Å (ZSM-5 zeolite), 40 Å (MCM-41 mesoporous material), and another porous system whose diameter is in the range of 100-500 Å (mesoporous system) formed by the burning of organic compounds that remain in the material during the calcination process. This pore system contributes to an increase in the catalytic performance of synthesized material.The results of vegetable oil sludge cracking reaction show that the product consists of fractions such as dry gas, liquefied petroleum gas (LPG), gasoline, light cycle oil (LCO), and (heavy cycle oil) HCO, which are similar to those of petroleum cracking process.MC-ZSM-5/MCM-41 catalyst is efficient in the catalytic cracking reaction of vegetable oil sludge as it has higher conversion and selectivity for LPG and gasoline products in comparison to the pyrolysis process. Product distribution (% of oil feed) of cracking reaction over MC-ZSM-5/MCM-41 is coke (3.4), total dry gas (7.0), LPG (31.1), gasoline (42.4), LCO (8.9), HCO (7.2); and that of pyrolysis are coke (19.0), total dry gas (9.3), LPG (16.9), gasoline (28.8), LCO (13.7), and HCO (12.3).These results have indicated a new way to use agricultural waste such as rice husk for the production of promising catalysts and the processing of vegetable oil sludge to obtain biofuel.     

Novel synthesis of ordered mesoporous materials Al-MCM-41 from bentonite

This paper reports the synthesis of ordered mesoporous materials Al-MCM-41 with a specific surface area of 1018 m²/g from bentonite. Pretreated bentonite was simultaneously used as silica and aluminum sources without addition of silica or aluminum reagents. Orthogonal experiments were adopted to optimize the processing parameters. The samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N₂ adsorption–desorption measurements and Fourier transform infrared spectra (FTIR) techniques. The obtained materials were hexagonal Al-MCM-41. Calcination removed the surfactant while new bonds increased the crosslinking of the frameworks. Proper Si/Al molar ratio was critical for the formation of highly ordered mesoporous materials.     

SOLID BASE CATALYZED TRANSESTERIFICATION OF CANOLA OIL

Catalytic activities of synthesized solid base catalysts (alumina loaded with solution of different potassium compounds such as KI, KF, K₂CO₃, and KNO₃ with the loading amount of 35 wt.%) were tested for the transesterification reaction of canola oil with methanol and ethanol in a batch reactor in a temperature range of 25–60°C and different feed ratios of methanol/oil between 6:1 and 18:1. Synthesized KF/Al₂O₃ solid base catalyst showed the highest activity in the transesterification of canola oil with methanol and gave much stabler methyl ester content during the reaction with the highest yield of 99.6% at the end of the eight-hour reaction time at 60°C, with a methanol/oil ratio of 15:1 and a catalyst amount of 3 wt.%. Formation of K₂O phase and the formation of the surface Al-O-K groups by salt-support interactions were observed during the synthesis of the catalysts. Methanol was found to be much more reactive than ethanol in the transesterification reaction.     

Al2O3-supported Mixed Ca and Zn Compounds Prepared from Waste Seashells for Synthesis of Palm Fatty Acid Methyl Esters

Waste mixed seashells of Perna viridis, Anadara granosa, Amusium pleuronectes, and Meretrix meretrix, as abundant, low-cost, and nontoxic calcium sources, were used as renewable raw materials in the preparation of a heterogeneous base catalyst for the transesterification of palm oil in refluxed methanol. The new mixed metal compound catalyst was prepared by mixing the calcined seashells with Zn(NO₃)₂ and Al₂O₃ in an acidic aqueous solution, followed by calcination at 500°C (ZSA-500). The ZSA-500 catalyst exhibited an enhanced surface area, dispersion, and total basicity compared to the parent calcined seashells. The fatty acid methyl ester (FAME) yield attained over ZSA-500 was 99 wt.% and dropped by 3% after five repetitive uses when the reaction was performed for 3 h at 60°C and ambient pressure with 10 wt.% catalyst and a methanol:oil molar ratio of 30:1. Structural and thermal analysis indicated that the active phases of ZSA-500 had a high stability against the glycerol adsorption as well as the phase transformation to calcium glyceroxides (Ca(C₃H₇O₃)₂).     

Biodiesel production from waste cooking oil over alkaline modified zirconia catalyst

Screening and catalytic activity of alkaline modified zirconia i.e. Mg/ZrO₂, Ca/ZrO₂, Sr/ZrO₂, and Ba/ZrO₂ as heterogeneous catalyst in biodiesel production from waste cooking oil (WCO) have been investigated. The catalysts were prepared via wet impregnation of alkaline nitrate salts supported on zirconia. Physico-chemical characteristics of the catalysts were analyzed by BET surface area, XRD, FESEM and CO₂–NH₃–TPD. Among the catalysts screened, Sr/ZrO₂ exhibited higher catalytic activities. Characterization results disclosed Sr/ZrO₂ catalyst possessed balanced basic and acid site concentrations with its pore volume, surface area as well as pore diameters suitable for biodiesel production. The balanced active sites facilitated simultaneous transesterification and esterification of WCO. A plausible mechanism has been suggested for the simultaneous reactions. The effects of operating process conditions such as methanol to oil molar ratio, reaction temperature and catalyst loading on biodiesel production in the presence of Sr/ZrO₂ were investigated. Methyl ester (ME) yield at 79.7% was produced over 2.7 wt.% catalyst loading (Sr/ZrO₂), 29:1 methanol to oil molar ratio, 169 min of reaction time and 115.5 °C temperature.