Optimisation of the synthesis of an analogue of jojoba oil using a fully central composite design

The development and optimisation of the synthesis of an analogue of jojoba oil has been carried out. The product is an ester with characteristics similar to those of sperm whale oil and jojoba oil. This permits its use as a substitute for these two natural oils. A central composite design has been used in the synthesis of this fine chemical. The variables selected for the present study are reaction temperature, initial concentration of catalyst and working pressure. Temperature is the most significant factor in the esterification process, and its influence is positive. Pressure has a negative influence, and the concentration of catalyst a positive influence, on the process. Depending on the temperature value, the influence of the interactions can be more important than that of the other two main effects, pressure and catalyst concentration. Response surface models have been found adequately to represent the yield of ester. The commercial quality of the synthesised product is very similar to that of natural jojoba oil. Because of its low cost, this synthesis process is considered, from an economical point of view, very attractive.     

Optimization of a process for the synthesis of a sperm whale oil analogue

The development and optimization of the synthesis of an analogue of sperm whale oil have been carried out. The product is an ester with characteristics similar to those of natural sperm whale oil. A central composite design was applied in the synthesis of this fine chemical. The variables selected for the present study are reaction temperature, initial concentration of catalyst and working pressure. Temperature is the most significant factor in the esterification process, and its influence is positive. Pressure influence can be neglected, and the catalyst concentration has a positive influence on the process. Depending on the temperature value, the influence of the interactions can be more important than that of the other two main effects, pressure and catalyst concentration. Response surface models have been found adequate to represent the yield of ester. The commercial quality of the synthesized product is very similar to that of natural spermaceti. Because of its low cost, this synthesis process is considered, from an economical point of view, very attractive.     

Extraction of jojoba seed oil using supercritical CO2+ethanol mixture in green and high-tech separation process

In this study, the extraction of jojoba seed oil obtained from jojoba seed using both supercritical CO₂ and supercritical CO₂+ethanol mixtures was investigated. The recovery of jojoba seed oil was performed in a green and high-tech separation process. The extraction operating was carried out at operating pressures of 25, 35 and 45 MPa, operating temperatures of 343 and 363 K, supercritical fluid flow rates of 3.33 × 10⁻⁸, 6.67 × 10⁻⁸ and 13.33 × 10⁻⁸ m³ s⁻¹, entrainer concentrations of 2, 4 and 8 vol.%, and average particle diameters of 4.1 × 10⁻⁴, 6.1 × 10⁻⁴, 8.6 × 10⁻⁴ and 1.2 × 10⁻³ m. It was found that a green chemical modifier such as ethanol could enhance the solubilities, initial extraction rate and extraction yield of jojoba seed oil from the seed matrix as compared to supercritical CO₂. In addition, it was found that the solubility, the initial extraction rate and the extraction yield depended on operating pressure and operating temperature, entrainer concentration, average particle size and supercritical solvent flow rate. The solubility of jojoba seed oil and initial extraction rate increased with temperature at the operating pressures of 35 and 45 MPa and decreased with increasing temperature at the operating pressure of 25 MPa. Furthermore, supercritical fluid extraction involved short extraction time and minimal usage of small amounts entrainer to the CO₂. About 80% of the total jojoba seed oil was extracted during the constant rate period at the pressure of 35 and 45 MPa.     

Optimization of <Emphasis Type="Italic">Brassica carinata</Emphasis> oil methanolysis for biodiesel production

Synthesis of FAME from Brassica carinata oil to produce biodiesel was accomplished using potassium hydroxide as the catalyst. A factorial design of experiments and a central composite design were used. The variables chosen were: type of Brassica carinata oil, initial catalyst concentration, and temperature; and the responses were FAME purity and yield. The type of B. carinata oil included high-erucic B. carinata (HEBC) and lowerucic B. carinata (LEBC) varieties. The results show that the type of B. carinata oil does not affect the purity and yield of FAME. However, HEBC oil is more suitable for biodiesel production because its iodine value is lower and within the European Union specifications. The initial catalyst concentration is the most important factor, having a positive influence on FAME purity but a negative effect on FAME yield. The temperature has a significant positive effect on FAME purity and a significant negative influence on FAME yield. Second-order models were obtained to predict FAME purity and yield as a function of catalyst concentration and temperature for HEBC oil methanolysis. The best conditions for this process are 25°C, and 1.2–1.5 wt% for the catalyst concentration.     

Transesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical and subcritical methanol

Transesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical/subcritical methanol was studied. The effects of various reaction variables such as the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil on the conversion of crude Jatropha curcas L. oil to biodiesel were investigated. The results showed that even micro‐NaOH could noticeably improve this reaction. When NaOH was added from 0.2 to 0.5 to 0.8 wt‐‰ of triacylglycerols, the transesterification rate increased sharply; when the catalyst content was further increased, the reaction rate was just poorly improved. It was observed that increasing the reaction temperature had a favorable influence on the methyl ester yield. For the molar ratio ranging from 18 to 36, the higher the molar ratio of methanol to oil was charged, the faster the transesterification rate seemed. At the fixed stirring rate of 400 rpm, when the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil were developed at 0.8 wt‐‰ NaOH, 523 K, 7.0 MPa and 24 : 1, respectively, the methyl ester yield could reach 90.5% within 28 min. Further, the kinetics of this reaction was involved and the results showed that it was a pseudo‐first‐order reaction whose apparent activation energy was 84.1 kJ/mol, and the pre‐exponential factor was 2.21×10⁵.     

Ethanolysis of Refined Soybean Oil Assisted by Sodium and Potassium Hydroxides

The ethanolysis of refined soybean oil was investigated through a 2³ experimental design that was carried out under the following levels: ethanol:oil molar ratios (MR) of 6:1 and 12:1, NaOH concentrations of 0.3 and 1.0 wt% in relation to the oil mass, and reaction temperatures of 30 and 70 °C. The ethanol:oil MR and the alkali concentration had an almost equivalent influence on the reaction yield, whereas the influence of increased reaction temperatures was very limited and higher catalyst concentrations led to greater yield losses due to the formation of soap. Ethyl ester yields of 97.2% were obtained at 70 °C, MR of 12:1 and 0.3 wt% NaOH. Replacement of 0.3 wt% NaOH by 1.0 wt% KOH under the same reaction conditions led to lower ester yields. Likewise the former, KOH provided the maximum ester yield (95.6%) at the highest molar ratio (12:1), with the reaction temperature having little influence on the catalyst performance. Ester yields beyond 98% were only achieved when a second ethanolysis stage was included in the process. In this regard, the application of 2 wt% Magnesol^® after the first ethanolysis stage eliminated the need for water washing prior to the second ethanolysis stage and helped to generate a final product with less contaminating unreacted glycerides.     

Continuous synthesis of castor oil ethyl esters under supercritical ethanol

The transesterification of castor oil under supercritical ethanol using a catalyst-free continuous process was investigated. The effect of water concentration on the reaction medium, reaction temperature, pressure, and substrates flow rate were studied. A maximum ester content of 74.2% was achieved when the reactor was operated at 573 K, 20 MPa, substrates flow rate of 0.8 ml min⁻¹, and 5 wt% water concentration in the alcohol. The ester content of the product increased with the operation temperature, but after certain temperature level the converse effect was observed. This adverse effect was attributed to oil degradation, which increased to 88.7% at 648 K (at the flow rate of 0.8 ml min⁻¹). A favorable effect on ester content was observed when the water concentration was increased, unlike the effect of water on the conventional alkali-catalyzed process.     

Continuous slurry hydrogenation of soybean oil with copper-chromite catalyst at high pressure

Selective hydrogenation of soybean oil to reduce linolenic acid is accomplished better with copper than with nickel catalysts. However, the low activity of copper catalysts at low pressure and the high cost of batch equipment for high-pressure hydrogenation has precluded their commercial use so far. To evaluate continuous systems as an alternative, soybean oil was hydrogenated in a 120 ft × 1/8 in. tubular reactor with copper catalyst. A series of hydrogenations were performed according to a statistical design by varying processing conditions: oil flow (0.5 L/hr, 1.0 L/hr and 2.0 L/hr), reaction temperature (180 C and 200 C), hydrogen pressure (1,100 psig and 4,500 psig) and catalyst concentration (0.5% and 1.0%). An iodine value (IV) drop of 8–43 units was observed in the products whereas selectivity varied between 7 and 9. Isomerization was comparable to that observed with a batch reactor. Analysis of variance for isomerization indicated interaction between catalyst concentration and hydrogen pressure and between catalyst concentration and temperature. The influence of pressure on linolenate selectivity was different for different temperatures and pressure. Hydrogenation rate was significantly affected by pressure, temperature and catalyst concentration.     

Solubilities of Soybean Oil,Jojoba Oil and Cuticular Wax in Dense Carbon Dioxide

The solubility of jojoba oil in dense carbon dioxide has been investigated by a dynamic method between 100 and 2600 bar and at temperatures within the range 20 to 80° C. The solubility isotherms and isobars of jojoba oil are compared with those of soybean oil. The appearance of solubility maxima was demonstrated for both cases in the high pressure region. The results are discussed and their implications for preparative extraction pointed out. In order to optimize the precipitation conditions a study was made of the solubility of cuticular wax in the low pressure region as a function of temperature and this was compared with the behaviour of typical essential oil components. The available differences can be utilized for an effective preprecipitation of wax from essential oils.     

Highly stable Fe/γ‐Al2O3 catalyst for catalytic wet peroxide oxidation

BACKGROUND: A highly stable Fe/γ‐Al₂O₃ catalyst for catalytic wet peroxide oxidation has been studied using phenol as target pollutant. The catalyst was prepared by incipient wetness impregnation of γ‐Al₂O₃ with an aqueous solution of Fe(NO₃)₃· 9H₂O. The influence of pH, temperature, catalyst and H₂O₂ doses, as well as the initial phenol concentration has been analyzed. RESULTS: The reaction temperature and initial pH significantly affect both phenol conversion and total organic carbon removal. Working at 50 °C, an initial pH of 3, 100 mg L^?1 of phenol, a dose of H₂O₂ corresponding to the stoichiometric amount and 1250 mg L^?1 of catalyst, complete phenol conversion and a total organic carbon removal efficiency close to 80% were achieved. When the initial phenol concentration was increased to 1500 mg L^?1, a decreased efficiency in total organic carbon removal was observed with increased leaching of iron that can be related to a higher concentration of oxalic acid, as by‐product from catalytic wet peroxide oxidation of phenol. CONCLUSION: A laboratory synthesized γ‐Al₂O₃ supported Fe has shown potential application in catalytic wet peroxide oxidation of phenolic wastewaters. The catalyst showed remarkable stability in long‐term continuous experiments with limited Fe leaching, < 3% of the initial loading. Copyright © 2010 Society of Chemical Industry     

Supercritical fluid extraction of jojoba oil

Supercritical fluid extraction of jojoba oil from Simmondsia chinensis seeds using CO₂ as the solvent is presented in this study. The effects of process parameters such as pressure and temperature of extraction, particle size of jojoba seeds, flow rate of CO₂, and concentration of entrainer (hexane) on the extraction yield were examined. Increases in the supercritical CO₂ flow rate, temperature, and pressure generally improved the performance. The extraction yield increased as the particle size decreased, indicating the importance of decreasing intraparticle diffusional resistance. The maximum extraction yield obtained was 50.6 wt% with a 0.23-mm particle size and a 2 mL/min CO₂ flow rate at 90°C and 600 bar. Use of an entrainer at a concentration of 5 vol% improved the yield to 52.2 wt% for the same particle size and also enabled the use of relatively lower pressure and temperature, i.e., 300 bar and 70°C.     

The optimization of the ultrasound-assisted base-catalyzed sunflower oil methanolysis by a full factorial design

The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at different reaction conditions. A full factorial experiment 3³ with replication was performed. The effects of three reaction variables, methanol-to-oil molar ratio, catalyst loading and the reaction temperature on fatty acid methyl ester yield were evaluated by the analysis of variance and the multiple regression. At the 95% confidence level all three factors and the interaction of the reaction temperature and methanol-to-oil molar ratio were effective on fatty acid methyl ester formation, the most important factor being the catalyst loading. The relationship between the factors and their interactions was modeled by the second-order polynomial equation.     

Biodiesel production from waste cooking palm oil using calcium oxide supported on activated carbon as catalyst in a fixed bed reactor

A reactor has been developed to produce high quality fatty acid methyl esters (FAME) from waste cooking palm oil (WCO). Continuous transesterification of free fatty acids (FFA) from acidified oil with methanol was carried out using a calcium oxide supported on activated carbon (CaO/AC) as a heterogeneous solid-base catalyst. CaO/AC was prepared according to the conventional incipient-wetness impregnation of aqueous solutions of calcium nitrate (Ca(NO₃)₂·4H₂O) precursors on an activated carbon support from palm shell in a fixed bed reactor with an external diameter of 60 mm and a height of 345 mm. Methanol/oil molar ratio, feed flow rate, catalyst bed height and reaction temperature were evaluated to obtain optimum reaction conditions. The results showed that the FFA conversion increased with increases in alcohol/oil molar ratio, catalyst bed height and temperature, whereas decreased with flow rate and initial water content in feedstock increase. The yield of FAME achieved 94% at the reaction temperature 60 °C, methanol/oil molar ratio of 25: 1 and residence time of 8 h. The physical and chemical properties of the produced methyl ester were determined and compared with the standard specifications. The characteristics of the product under the optimum condition were within the ASTM standard. High quality waste cooking palm oil methyl ester was produced by combination of heterogeneous alkali transesterification and separation processes in a fixed bed reactor. In sum, activated carbon shows potential for transesterification of FFA.     

Liquid‐Phase Hydrogenation of m‐phenoxybenzaldehyde to m‐phenoxybenzylalcohol Using Raney Nickel Catalyst: Reaction Kinetics

Kinetics of the liquid‐phase catalytic hydrogenation of m‐phenoxybenzaldehyde to m‐phenoxybenzyl alcohol have been investigated over the Raney nickel catalyst. Effects of hydrogen partial pressure (500‐2000 kPa), catalyst loading (1.6‐6.4 g.L^?1), m‐phenoxybenzaldehyde concentration (0.2‐0.8 mol.L^?1) and temperature (333‐363 K) on the progress of the reaction were studied. The speed of stirring > 15 rps has no effect on the initial rate of reaction. Effects of various catalysts and solvents on the hydrogenation of m‐phenoxybenzaldehyde have been investigated. The reaction was found to be first order with respect to the hydrogen partial pressure, catalyst loading and m‐phenoxybenzaldehyde concentration. Several Langmuir‐Hinshelwood type models were considered and the experimental data fitted to the model involving surface reaction, between dissociatively adsorbed hydrogen and molecularly adsorbed m‐phenoxybenzaldehyde.     

Liquid‐Phase Catalytic Hydrogenation of p‐Chlorobenzophenone to p‐Chlorobenzhydrol over a 5 % Pd/C Catalyst

The kinetics of the liquid‐phase catalytic hydrogenation of p‐chlorobenzophenone have been investigated over a 5 % Pd/C catalyst. The effects of hydrogen partial pressure (800–2200 kPa), catalyst loading (0.4–1.6 gm dm^–3), p‐chlorobenzophenone concentration (0.37–1.5 mol dm^–3), and temperature (303–313 K) were studied. A stirring speed > 20 rps has no effect on the initial rate of reaction. Effects of various catalysts (Pd/C, Pd/BaSO₄, Pd/CaCO₃, Pt/C, Raney nickel) and solvents (2‐propanol, methanol, dimethylformamide, toluene, xylene, hexane) on the hydrogenation of p‐chlorobenzophenone were also investigated. The reaction was found to be first order with respect to hydrogen partial pressure and catalyst loading, and zero order with respect to p‐chlorobenzophenone concentration. Several Langmuir‐Hinshelwood type models were considered and the experimental data fitted to a model involving reaction between adsorbed p‐chlorobenzophenone and hydrogen in the liquid phase.     

Modeling of poly(ethylene terephthalate) reactors. I. A semibatch ester interchange reactor

A comprehensive model for a semibatch ester interchange reactor has been developed with a view to investigate the effect of various process and operational variables on the DMT conversion rate as well as the by-product formation. The influence of important variables such as EG-to-DMT ratio, catalyst concentration, and operational variables such as temperature and pressure has been considered. Definite conclusions concerning the choice of the desirable range of process and operational variables to maximize productivity and minimize by-product formation have been reached.     

Biodiesel Synthesis from Styrax confusus Hemsl Catalyzed by S2O82−/ZrO2‐TiO2‐Fe3O4

Biodiesel has been identified as a suitable resource that can be produced from biomass such as Styrax confusus Hemsl. In the current study, biodiesel was synthesized from Styrax confusus Hemsl oil catalyzed by a magnetic solid acid heterogeneous catalyst S₂O₈^2?/ZrO₂‐TiO₂‐Fe₃O₄, which had a high recovery rate and reusability. The catalyst was prepared by co‐precipitation and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction and Brunauer, Emmett and Teller (BET) adsorption. The properties of the catalyst, including the recovery rate, usage count, magnetic susceptibility and catalytic efficiency, were studied. The results showed that the catalyst has a BET pore diameter of 1.74 nm, BET area of 7.3 m²/g, molar magnetic susceptibility of 1.83 × 10^?5 m³/kg and tetragonal structure. In addition, the influences of reaction conditions on yields of biodiesel were also discussed. A fatty acid methyl ester (FAME) yield of 90.02 % was obtained under the conditions of reaction time 1.5 h, reaction temperature 373 K, catalyst amount 5 %, and methanol‐to‐oil molar ratio 8:1. A FAME yield of 65.5 % was obtained when the catalyst was used for the fourth time.     

Optimum process and energy density analysis of canola oil biodiesel synthesis

Biodiesel has been recommended as an environmentally benign alternative fuel because it emits a comparatively small amount of air pollutants. Biodiesel can be processed from canola oil, which has a low liquefaction temperature owing to its high unsaturated fatty acid content, which also limits its engine-clogging effects. In this study, optimum conditions such as the amount of methanol, the alkali catalyst, and the reaction temperature were determined for production of biodiesel from canola oil. A maximum biodiesel yield was shown at an oil/methanol mole ratio of 1:6. The optimum amount of catalyst was 1 wt% of potassium hydroxide. The biodiesel yield and the methyl ester content were high when the reaction temperature was 55 °C. The consolute temperature for determining the maximum biodiesel yield was proposed in consideration of the boiling point of methanol. The energy density was analyzed for the final products of biodiesel in comparison to the raw canola oil and other plant oil based biodiesels.     

Production of bio‐crude from forestry waste by hydro‐liquefaction in sub‐/super‐critical methanol

Hydro‐liquefaction of a woody biomass (birch powder) in sub‐/super‐critical methanol without and with catalysts was investigated with an autoclave reactor at temperatures of 473–673 K and an initial pressure of hydrogen varying from 2.0 to 10.0 MPa. The liquid products were separated into water soluble oil and heavy oil (as bio‐crude) by extraction with water and acetone. Without catalyst, the yields of heavy oil and water soluble oil were in the ranges of 2.4–25.5 wt % and 1.2–17.0 wt %, respectively, depending strongly on reaction temperature, reaction time, and initial pressure of hydrogen. The optimum temperature for the production of heavy oil and water soluble oil was found to be at around 623 K, whereas a longer residence time and a lower initial H₂ pressure were found to be favorite conditions for the oil production. Addition of a basic catalyst, such as NaOH, K₂CO₃, and Rb₂CO₃, could significantly promote biomass conversion and increase yields of oily products in the treatments at temperatures less than 573 K. The yield of heavy oil attained about 30 wt % for the liquefaction operation in the presence of 5 wt % Rb₂CO₃ at 573 K and 2 MPa of H₂ for 60 min. The obtained heavy oil products consisted of a high concentration of phenol derivatives, esters, and benzene derivatives, and they also contained a higher concentration of carbon, a much lower concentration of oxygen, and a significantly increased heating value (>30 MJ/kg) when compared with the raw woody biomass. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Production of biodiesel by ultrasound assisted esterification of Oreochromis niloticus oil

This paper evaluates the production of methyl esters from Oreochromis niloticus (Nile tilapia) oil and methanol. The reaction was carried out applying low-frequency high-intensity ultrasound (40 kHz) under atmospheric pressure and ambient temperature. Response surface methodology (RSM) was used to evaluate the influence of alcohol to oil molar ratio, catalyst concentration (sulfuric acid) and temperature on the yield of O. niloticus oil into methyl esters. Analysis of the operating conditions by RSM showed that the most important operating condition affecting the reaction was the alcohol to FFA molar ratio. The highest yield observed was of 98.2% after 90 min of reaction. The optimal operating condition was obtained applying an alcohol to oil molar ratio of 9.0 and a catalyst concentration of 2.0% w/w and temperature of 30 °C.