Synthesis of fatty acid methyl esters via the methanolysis of palm oil over Ca3.5xZr0.5yAlxO3 mixed oxide catalyst

Novel mixed metal oxide catalyst Ca_3.5xZr_0.5yAl_xO₃ was synthesized through the coprecipitation of metal hydroxides. The textural, morphological, and surface properties of the synthesized catalysts were characterized via Brunauer–Emmett–Teller method, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. The catalytic performance of the as-synthesized catalyst series was evaluated during the transesterification of cooking palm oil with methanol to produce fatty acid methyl esters (FAME). The influence of different parameters, including the calcination temperature (300–700 °C), methanol to oil molar ratio (6:1–25:1), catalyst amount (0.5–6.5 wt%), reaction time (0.5–12 h) and temperature (70–180 °C), on the process was thoroughly investigated. The metal oxide composite catalyst with a Ca:Zr ratio of 7:1 showed good catalytic activity toward methyl esters. Over 87% of FAME content was obtained when the methanol to oil molar ratio was 12:1, reaction temperature 150 °C, reaction time 5 h and 2.5 wt% of catalyst loading. The catalyst could also be reused for over four cycles.     

Transesterification of canola oil as biodiesel over Na/Zr-SBA-15 catalysts: Effect of zirconium content

A series of mesoporous Zr-SBA-15-supported Na catalysts was prepared and applied to the heterogeneous catalysis of canola oil transesterification. The effects of Si/Zr ratio, reaction time, and percentage of Na loading on the conversion to fatty acid methyl esters (FAME) were studied. The dependence of the textural structure and chemical properties of Zr-SBA-15 supports on Zr content was investigated using small-angle X-ray diffraction, Brunauer–Emmett–Teller analysis, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The results obtained from FTIR and TEM indicate that the incorporation of Zr atoms into the SBA-15 structure facilitated the formation of Brönsted acid sites and decreased the particle size of Na species. Catalysts with a higher Zr content enhanced the FAME yield. The optimum conditions determined were as follows: reaction temperature of 70 °C, 15 wt.% Na, reaction time of 6 h, and 12% catalyst content (wt.% oil) with a methanol/oil molar ratio of 6:1. The optimum conditions resulted in a FAME yield of up to 99%.     

Synthesis and characterization of monk fruit seed (Siraitia grosvenorii)-based heterogeneous acid catalyst for biodiesel production through esterification process

This research investigated for the first time the synthesis of monk fruit seed (Siraitia grosvenorii)-based solid acid catalyst for biodiesel production. The catalyst was synthesized using a two-step surface functionalization method with trimethoxy phenyl silane and chlorosulfonic acid. The as-synthesized catalyst was characterized to ascertain its catalytic characteristics through surface morphology, chemical bonding, and thermal stability. The effects of activating agent impregnation ratio, carbonization temperature, and sulfonation temperature towards fatty acid methyl ester (FAME) yield were elucidated. The esterification reaction with palmitic acid was found to produce FAME yield up to 98.5% with 4 wt.% catalyst loading, 6-h reaction duration and 120°C reaction temperature. The catalyst also demonstrated high reusability with 84.4% FAME yield being successfully maintained after four successive cycles without reactivation. These proved that the as-synthesized catalyst had high prospect to become a suitable low-cost alternative for biodiesel production through catalytic esterification process in the future.     

Parametric study and optimization of in situ transesterification of Jatropha curcas L assisted by benzyltrimethylammonium hydroxide as a phase transfer catalyst via response surface methodology

In the present work, non-edible oil source, Jatropha curcas oil was used with base catalyzed methanol and ethanol to produce biodiesel using in situ transesterification assisted by Benzyltrimethylammonium hydroxide (BTMAOH) as a phase transfer catalyst (PTC). Experimental investigation showed that base catalyzed in situ transesterification reaction rate was enhanced with the use of BTMAOH as a PTC. During the experiment fast formation of biodiesel was observed in relatively shorter time for PTC assisted reaction as compared to the reaction in the absence of PTC. The effect of individual reaction parameters was investigated using response surface methodology (RSM). Optimum operating conditions were also found statistically. Weight fractions of 89 ± 0.7% fatty acid methyl esters (FAME) yield and 99.4 ± 0.4% fatty acid ethyl esters (FAEE) yield were produced at optimum reaction condition. The fuel quality of FAME and FAEE was investigated against the fuel quality specification set by ASTM D6751 and EN-14214 standards.     

Improving the yield of Jatropha curcas's FAME through sol–gel derived meso-porous hydrotalcites

The conversion of fatty acid methyl ester (FAME) from triglycerides using heterogeneous catalysis has gained increasing interest due to the prospect of increased yield at reduced operating costs and reaction conditions. In this paper, meso-porous hydrotalcite was used to catalyze jatropha oil into FAME with relatively higher yield at atmospheric pressure and relatively low reaction temperature. The molar ratio of methanol to oil required was relatively low and the conversion was completed within few hours of reaction time. The reaction was promoted when moderate calcination temperature was applied, the disordered structure of the catalyst was maintained, counterbalance anions was removed, and phase transitions within the oxide lattice was induced. Despite the observed deactivation during successive reaction cycles due to adsorption of residual triglycerides, the catalyst performance was restored effectively by air-re-calcination.     

Screening,optimization and kinetics of Jatropha curcas oil transesterification with heterogeneous catalysts

This work investigates the production of fatty acid methyl esters (FAME) from Jatropha curcas oil using a variety of heterogeneous catalysts: resins, zeolites, clays, hydrotalcites, aluminas and niobium oxide. For this purpose, a catalyst screening was first conducted in a batch reactor at the following operating conditions: oil to methanol molar ratio of 1:9, 6 h of reaction, 5 wt% catalyst, at 333 and 393 K. From the screening step, KSF clay and Amberlyst 15 catalysts were selected to carry out a 2³ full factorial central composite rotatable design so as to elucidate the effects of process variables on FAME yield. The optimum reaction conditions for both catalysts were found to be oil to methanol molar ratio of 1:12, 5 wt% of catalyst, 433 K and 6 h of reaction with a FAME yield of about 70 wt%. A kinetic study was then experimentally performed and a semi-empirical model was built to represent the experimental data. Finally, catalyst re-utilization in five successive batch experiments was evaluated at the optimized conditions.     

Synthesis of fatty acid methyl esters via the transesterification of waste cooking oil by methanol with a barium-modified montmorillonite K10 catalyst

The transesterification of waste cooking oil (WCO) with methanol to produce fatty acid methyl esters (FAMEs) in the presence of barium-modified montmorillonite K10 (BMK10) catalyst was investigated in a batch reactor. The influence of the reaction parameters on the yield of FAME was investigated. The highest value of 83.38% was obtained with 3.5 wt% catalyst loading at 150 °C with a methanol: oil molar ratio of 12:1 during a reaction time of 5 h. BMK10 is a promising low-cost catalyst for the transesterification of WCO to produce FAME.     

Preparation, characterization and application of heterogeneous solid base catalyst for biodiesel production from soybean oil

A solid base catalyst was prepared by neodymium oxide loaded with potassium hydroxide and investigated for transesterification of soybean oil with methanol to biodiesel. After loading KOH of 30 wt.% on neodymium oxide followed by calcination at 600 °C, the catalyst gave the highest basicity and the best catalytic activity for this reaction. The obtained catalyst was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), N₂ adsorption-desorption measurements and the Hammett indicator method. The catalyst has longer lifetime and maintained sustained activity after being used for five times, and were noncorrosive and environmentally benign. The separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and reaction time were investigated. The experimental results showed that a 14:1 M ratio of methanol to oil, addition of 6.0% catalyst, 60 °C reaction temperature and 1.5 h reaction time gave the best results and the biodiesel yield of 92.41% was achieved. The properties of obtained biodiesel are close to commercial diesel fuel and is rated as a realistic fuel as an alternative to diesel.     

Synthesis of glycerol-free fatty acid methyl ester using interesterification reaction based on solid acid carbon catalyst derived from low-cost biomass wastes

The current research was aimed to corroborate as well as compare the feasible applicability of waste banana peel and empty fruit bunch (EFB) in synthesising high-performing heterogeneous catalysts. The solid acid catalysts originated from biomass wastes were employed for the synthesis of glycerol-free fatty acid methyl ester (FAME) using catalytic interesterification process pathway. Acetic acid was produced as the by-product instead of glycerol. The heterogeneous acid catalysts were synthesised utilising sulphuric acid through direct sulfonation with thermal treatment. The concentration of the sulphuric acid was manipulated from 2 to 13 mol L^?1 to investigate its effects on the resulting FAME yield while maintaining the sulfonating ratio at 10 mL g^?1. The catalytic performances of the as-synthesised catalysts were studied under reaction conditions of 12 wt % catalyst loading, 50:1 methyl acetate to oleic acid molar ratio for a duration of 8 hours at 60°C. The catalyst produced by activated carbon derived from EFB and sulfonated with 13 mol L^?1 sulphuric acid exhibited the highest FAME yield at 44.3%. The parameter studies on reactant ratio (45:1-70:1), reaction temperature (90°C-130°C) and time (4-24 hours) of interesterification reaction discovered a general increasing trend in the FAME yield up to 52.3% with the optimum conditions of 50:1, 110°C and 8 hours, respectively. The catalyst was recyclable with 82% of the catalytic performance retained after five successive cycles with catalyst reactivation. This study confirmed that the renewable heterogeneous catalyst derived from biomass waste could catalyse the glycerol-free interesterification process via an environmentally benign and promising approach for green fuel production.     

Biodiesel synthesis from Hevea brasiliensis oil employing carbon supported heterogeneous catalyst: Optimization by Taguchi method

The present work illustrates the parametric effects on biodiesel production from Hevea brasiliensis oil (HBO) using flamboyant pods derived carbonaceous heterogeneous catalyst. Activated carbon (AC) was prepared maintaining 500 °C for 1 h and steam activated at optimised values of activation time 1.5 h and temperature 350 °C. Carbonaceous support was impregnated with KOH at different AC/KOH ratios. The transesterification process was optimized and significant parameters affecting the biodiesel yield was identified by Taguchi method considering four parameters viz. reaction time, reaction temperature, methanol to oil ratio and catalyst loading. The physicochemical properties of Hevea brasiliensis methyl ester (HBME) were examined experimentally at optimised condition and found to meet the global American standards for testing and materials (ASTM). The optimum condition observed to yield 89.81% of biodiesel were: reaction time 60 min, reaction temperature 55 °C, catalyst loading 3.5wt% and methanol to oil ratio 15:1. Contribution factor revealed that among four parameters considered, catalyst loading and methanol to oil ratio have more prominent effect on biodiesel yield. The cost for preparing carbonaceous catalyst support was estimated and observed to be fairly impressive. Thus, Hevea brasiliensis oil (HBO) could be considered as suitable feedstock and flamboyant pods derived carbon as effective catalyst for production of biodiesel.     

Study on the use of MgAl hydrotalcites as solid heterogeneous catalysts for biodiesel production

This paper, reports experimental work on the use of new heterogeneous solid basic catalysts for biodiesel production: double oxides of Mg and Al, produced by calcination, at high temperature, of MgAl lamellar structures, the hydrotalcites (HT). The most suitable catalyst system studied are hydrotalcite Mg:Al 2:1 calcinated at 507 °C and 700 °C, leading to higher values of FAME also in the second reaction stage. One of the prepared catalysts resulted in 97.1% Fatty acids methyl esters (FAME) in the 1st reaction step, 92.2% FAME in the 2nd reaction step and 34% FAME in the 3rd reaction step. The biodiesel obtained in the transesterification reaction showed composition and quality parameters within the limits specified by the European Standard EN 14214. 2.5% wt catalyst/oil and a molar ratio methanol:oil of 9:1 or 12:1 at 60–65 °C and 4 h of reaction time are the best operating conditions achieved in this study. This study showed the potential of Mg/Al hydrotalcites as heterogeneous catalysts for biodiesel production.     

Effects of enzymatic hydrolysis on lipid extraction from Chlorella vulgaris

In this study, the effects of enzymatic hydrolysis on lipid extraction from microalga (Chlorella vulgaris) were investigated prior to biodiesel production. The initial fatty acids content of C. vulgaris was 87.6 mg/g cell. The microalgal cell walls were hydrolyzed by cellulases and then their lipid fractions were extracted using various organic solvents such as hexane, methanol, and chloroform. Optimal pH and temperature for the enzymatic hydrolysis were pH 4.8 and 50 °C, respectively, and the maximal hydrolysis yield was 85.3%, which was achieved after 72 h. After the enzymatic hydrolysis, the lipid extraction yield by the organic solvents was improved compared to when there was no enzymatic hydrolysis process, by 1.29–1.73-fold depending on the solvents used. The total fatty acid methyl ester (FAME) productivity through the enzymatic hydrolysis was higher than when there was no enzymatic hydrolysis, by 1.10–1.69-fold depending on the solvents used. When lipid was extracted from the C. vulgaris after the enzymatic hydrolysis in chloroform-methanol solution, FAME productivity was 59.4 mg FAME/g cell.     

Influences of tungsten incorporation,morphology and calcination temperature on the electrocatalytic activity of Ni/C nanostructures toward urea elimination from wastewaters

Electrooxidation of urea is an efficient methodology for the production of hydrogen with a simultaneous treatment of urea-containing wastewaters. In this study, tungsten was suggested as a co-catalyst to foster the activity of Ni/C nanostructures in the process of urea electro-oxidation. Beside optimization of the co-catalyst content, influences of the nano-morphology and the synthesis temperature have been investigated. The results indicated that WNi nanoparticles-incorporated carbon nanofibers can be produced from calcination of electrospun mats composed of nickel acetate, tungsten chloride, and ploy (vinyl alcohol). Compared to the nanoparticles, the morphology of nanofibrous was strongly foster the electrocatalytic activity. The W-free and the prepared, from calcination of an electrospun solution containing 10 wt% WCl₂ at 850 °C, nanofibers give better performance compared to the nanoparticles having similar compositions. Compared to the nanoparticles, the nanofibrous morphology results in increasing the current density from 11.5 to 16 mA/cm² (28% increase) and from 22 to 37.75 mA/cm² (42% increase) for the pristine and W- containing catalyst, respectively. Studying the influence of the metallic nanoparticles composition indicated that the tungsten content strongly affects the electrocatalytic activity; the nanofibers prepared from electrospun solution containing 35 wt% tungsten precursor reveal the best performance. Investigating the effect of the calcination temperature indicated that 1000 °C is the optimum temperature compared to 700 and 850 °C. Numerically, for 10 wt% co-catalyst sample, the current density was duplicated four times when the calcination temperature increased from 850 to 1000 °C. Studying the kinetic of urea oxidation reaction concluded that the activation energy is ~17 kJ/mol.     

Methane decomposition with a minimal catalyst: An optimization study with response surface methodology over Ni/SiO2 nanocatalyst

Nowadays, methane cracking in the presence of an efficient catalyst is one of the most investigating areas aiming hydrogen and nanocarbon synthesis. This research contribution systematically investigated the influence of methane partial pressure (P_CH4), decomposition temperature, and weight of Ni/SiO₂ nanocatalyst (n-Ni/SiO₂) on carbon nanotube (CNT) yield. The optimum reaction condition for optimal methane cracking resulted in maximum CNT yield is derived using Design Expert Software. A series of experiments conducted to develop a quadratic polynomial model for CNT yield using response surface methodology. Surprisingly, the optimum catalyst quantity was the lowest (0.30 g) in the experimented parameter range, which exhibited the highest CNT production at 610 °C temperature and 0.8 atm P_CH4. The minimal catalyst quantity for the optimum CNT production, which needs only 0.26% of the total volume of the pilot plant reactor, is a breakthrough finding in methane cracking research. It could help to overcome the reactor blockage limitation issues of the process in large scale applications. Thanks to the uniquely supported n-Ni/SiO₂ catalyst prepared via co-precipitation cum modified Stöber method. The fresh and used catalysts investigated using different types of characterization techniques such as XRD, BET, Raman spectra, HRTEM, and FESEM-EDX. Characterization results evidenced the presence of differently structured CNTs formed at optimum reaction conditions.     

Effect of N2O-mediated calcination on nickel species and the catalytic activity of nickel catalysts supported on γ-Al2O3 in the steam reforming of glycerol

The steam reforming of glycerol over supported nickel catalysts is a promising and cost-effective method for producing hydrogen. The activity of nickel catalysts supported on γ-Al₂O₃ is low, primarily due to the formation of inactive nickel species during high temperature calcination in air. In order to address this problem, a Ni/γ-Al₂O₃ catalyst was prepared by calcination at 700 °C in a nitrous oxide (N₂O) environment. The N₂O calcined catalyst showed an enhanced activity for the steam reforming of glycerol. A variety of characterization techniques (XRD, TPR, XPS and H₂ Chemisorption) confirmed that the high temperature N₂O calcination resulted in a significant decrease in the levels of nickel aluminate. The N₂O calcination also led to an enhancement in the amount of NiO as well as nickel ions present on the surface of the catalyst. Interestingly, compared to an air calcined catalyst, the N₂O calcined catalyst contained larger nickel particles after reduction but the N₂O calcined catalyst had a much larger nickel surface area and dispersion, which resulted in higher glycerol conversion and hydrogen yield.     

Production of FAME by palm oil transesterification via supercritical methanol technology

The present study employed non-catalytic supercritical methanol technology to produce biodiesel from palm oil. The research was carried out in a batch-type tube reactor and heated beyond supercritical temperature and pressure of methanol, which are at 239 °C and 8.1 MPa respectively. The effects of temperature, reaction time and molar ratio of methanol to palm oil on the yield of fatty acid methyl esters (FAME) or biodiesel were investigated. The results obtained showed that non-catalytic supercritical methanol technology only required a mere 20 min reaction time to produce more than 70% yield of FAME. Compared to conventional catalytic methods, which required at least 1 h reaction time to obtain similar yield, supercritical methanol technology has been shown to be superior in terms of time and energy consumption. Apart from the shorter reaction time, it was found that separation and purification of the products were simpler since no catalyst is involved in the process. Hence, formation of side products such as soap in catalytic reactions does not occur in the supercritical methanol method.     

Optimization of transesterification conditions for the production of fatty acid methyl ester (FAME) from Chinese tallow kernel oil with surfactant-coated lipase

Surfactant-coated lipase was used as a catalyst in preparing fatty acid methyl ester (FAME) from Chinese tallow kernel oil from Sapium sebiferum (L.) Roxb. syn. Triadica sebifera (L.) small. FAME transesterification was analyzed using response surface methodology to find out the effect of the process variables on the esterification rate and to establish prediction models. Reaction temperature and time were found to be the main factors affecting the esterification rate with the presence of surfactant-coated lipase. Developed prediction models satisfactorily described the esterification rate as a function of reaction temperature, time, dosage of surfactant-coated lipase, ratio of methanol to oil, and water content. The FAME mainly contained fatty acid esters of C16:0, C18:0, C18:1, C18:2, and C18:3, determined by a gas chromatograph. The optimal esterification rate was 93.86%. The optimal conditions for the above esterification ratio were found to be a reaction time of 9.2 h, a reaction temperature of 49 °C, dosage of surfactant-coated lipase of 18.5%, a ratio of methanol to oil of 3:1, and water content of 15.6%. Thus, by using the central composite design, it is possible to determine accurate values of the transesterification parameters where maximum production of FAME occurs using the surfactant-coated lipase as a transesterification catalyst.     

A highly active and stable chromium free iron based catalyst for H2 purification in high temperature water gas shift reaction

In this work mesoporous nanocrystalline chromium free Fe–Al–Ni catalysts with various Fe/Al and Fe/Ni ratios were prepared by coprecipitation method for high temperature water gas shift reaction. The prepared catalysts were characterized using X-ray diffraction (XRD), N₂ adsorption (BET), temperature-programmed reduction (TPR) and transmission electron microscopy (TEM) techniques. The catalytic results revealed that the catalyst with Fe/Al = 10 and Fe/Ni = 5 weight ratios exhibited the highest catalytic activity among the prepared catalysts and the commercial chromium containing one. This catalyst possessed a high surface area of 177.4 m² g⁻¹ with an average pore size of 4.3 nm with a high stability during 20 h time on stream. Furthermore, the effect of calcination temperature, GHSV and steam/gas ratio on the structural properties and catalytic performance of the catalyst with the highest activity was investigated.     

Effects of water on the esterification of free fatty acids by acid catalysts

To maximize the production of biodiesel from soybean soapstock, the effects of water on the esterification of high-FFA (free fatty acid) oils were investigated. Oleic acid and high acid acid oil (HAAO) were esterified by reaction with methanol in the presence of Amberlyst-15 as a heterogeneous catalyst or sulfuric acid as a homogeneous catalyst. The yield of fatty acid methyl ester (FAME) was studied at oil to methanol molar ratios of 1:3 and 1:6 and reaction temperatures of 60 and 80 °C. The rate of esterification of oleic acid significantly decreased as the initial water content increased to 20% of the oil. The activity of Amberlyst-15 decreased more rapidly than that of sulfuric acid, due to the direct poisoning of acid sites by water. Esterification using sulfuric acid was not affected by water until there was a 5% water addition at a 1:6 molar ratio of oil to methanol. FAME content of HAAO prepared from soapstock rapidly increased for the first 30 min of esterification. Following the 30-min mark, the rate of FAME production decreased significantly due to the accumulation of water. When methanol and Amberlyst-15 were removed from the HAAO after 30 min of esterification and fresh methanol and a catalyst were added, the time required to reach 85% FAME content was reduced from 6 h to 1.8 h.     

Influence of the calcination temperature on the structure and reducibility of nanoceria obtained from crystalline Ce(OH)CO3 precursor

A high yield green method was developed for the preparation of reactive nanotextured ceria (CeO₂). The preparation method is based on the oxidation of a crystalline Ce(OH)CO₃ precursor that decompose at relative low temperature (ca. 250 °C) yielding CeO₂ nanocrystals initially rich in Ce³⁺. After increasing calcination temperatures (in the range 350-650 °C), PXRD analysis show a slight crystal growth after calcination temperatures up to 550 °C, however cell contraction in such case denotes the definitive oxidation of remnant Ce³⁺ centers. XPS results confirm Ce³⁺ fraction diminution as calcination temperature increases. TPR profiles of ceria samples show two reduction events being the low temperature one (at ca. 500 °C) related to a surface process in which approximately only one cerium monolayer is involved. Catalytic activity tests for COPROX reaction were performed under differential reactor conditions to evaluate their activity in the temperature range 100-300 °C. The optimum activity recorded for the sample calcined at 450 °C accounts for the compromise between oxide’s activation and surface preservation.