Transesterification of sunflower oil in a countercurrent trickle-bed reactor packed with a CaO catalyst

Transesterification of sunflower oil with methanol to form biodiesel was performed in a countercurrent trickle-bed reactor, using calcium oxide particles 1-2 mm in diameter as a packed, solid base catalyst. Although biodiesel production generally requires a reaction temperature below the boiling point of methanol to maintain a heterogeneous, liquid-liquid reaction, in the present study the reaction temperature was varied from 80 to 140 °C to confirm the progress of transesterification in a gas-liquid-solid phase reaction system. Oil droplets released from a thin tube flowed downward, while vaporized methanol flowed upward in the bed. The effects of the reaction temperature, methanol and oil flow rates, and the bed height on the FAME yield were investigated. The oil residence time in the reactor, which was controlled by changing both the oil flow rate and the bed height, had a significant effect on the FAME yield. In addition, the FAME yield increased with reaction temperature and was maximal at 373 K due to the change in residence time associated with reduced oil viscosity at higher temperatures. The FAME yield was 98% at a reaction temperature of 373 K when the methanol and oil flow rates were 3.8 and 4.1 mL/h, respectively.     

Kinetics of the base-catalyzed sunflower oil ethanolysis

The kinetics of the sunflower oil ethanolysis process using NaOH as a catalyst was studied at different reaction conditions. The reaction system was considered as a pseudo-homogeneous one with no mass transfer limitations. It was also assumed that the chemical reaction rate controlled the overall process kinetics. A simple kinetic model consisting of the irreversible second-order reaction followed by the reversible second-order reaction close to the completion of the ethanolysis reaction was used for the simulation of the triglyceride conversion and the fatty acid ethyl ester formation. The proposed kinetics model fitted the experimental data well.     

Premium quality renewable diesel fuel by hydroprocessing of sunflower oil

Hydroprocessing of neat sunflower oil was carried out at 360-420 °C and 18 MPa over a commercial hydrocracking catalyst in a bench scale fixed bed reactor. In the studied experimental range, products consisted exclusively of hydrocarbons that differed significantly in composition. While the concentration of n-alkanes exceeded 67 wt.% in the reaction products collected at 360 °C, it decreased to just 20 wt.% in the product obtained at 420 °C. Consequently, the fuel properties of the latter product were very similar to those of standard (petroleum-derived) diesel fuel. Particularly, it exhibited excellent low-temperature properties (cloud point −11 °C; CFPP −14 °C). Reaction products obtained at 400 and 420 °C were blended into petroleum-derived diesel fuel in three concentration levels ranging from 10 to 50 wt.% and the fuel properties of these mixtures were evaluated. Diesel fuel mixtures containing the product of sunflower oil hydrocracking at 420 °C showed very good low-temperature properties including cloud point (−8 °C) and CFPP (−15 °C) that was further lowered to −25 °C due to addition of flow improvers.     

Conventional and in situ transesterification of sunflower seed oil for the production of biodiesel

In the present work the alkaline transesterification of sunflower seed oil with methanol and ethanol, for the production of biodiesel fuel was studied. Both conventional and in situ transesterification were investigated using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm). Use of ultrasonication in conventional transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Use of ultrasonication in conventional transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ transesterification the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol use of ultrasonication led to high ester yields (98%) in only 40 min of reaction time while use of mechanical stirring gave lower yields (88%) even after 4 h of reaction time.

 In situ transesterification gave similar ester yields to those obtained by conventional transesterification being an alternative, efficient and economical process. In all cases a concentration of 2.0% NaOH gave higher ester yields.

 Reaction rate constants were calculated, using first order reaction kinetics, to be equal to 3.1 × 10^− 3 s^− 1 for conventional transesterification using methanol and 2.0% NaOH, and 9.5 × 10^− 4 s^− 1 using ethanol.     

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.     

Kinetics of biodiesel synthesis from sunflower oil over CaO heterogeneous catalyst

Calcium oxide as a heterogeneous catalyst was investigated for its effect on the biodiesel synthesis from refined sunflower oil. Experiments were carried out using a commercial bench stirred tank reactor of 2 dm³ volume, at 200 rpm, with a methanol to oil ratio 6 to 1 and 1 mas.% catalyst loading as constant parameters. Ester yields were followed as a function of temperature (60-120 °C), pressure (1-15 bars) and reaction time (1.5-5.5 h). The temperature of 100 °C was found to be optimal for the maximum (91%) conversion to methyl esters, while pressure had a positive impact up to 10 bars at 80 °C. The catalyst activation in air leading to the formation of strong basic sites was found to occur at 900 °C. Catalyst particle coalescence took place during the reaction, giving a gum-like structure, and resulted in a significant catalyst deactivation. The pseudo-first order reaction was established, with a “knee” at 80 °C in the Arrhenius plot separating the kinetic and diffusion regimes. During the reaction progress, an activation energy decrease from 161 to 101 kJ/mol, and from 32 to (−3) kJ/mol, was found for the kinetic and diffusion regimes, respectively.     

Variation of physical properties during transesterification of sunflower oil to biodiesel as an approach to predict reaction progress

Biodiesel as a pure, non-toxic, biodegradable and renewable alternative for fossil diesel fuel has attracted much attention in recent decade. Thus, demands for researches in this field are growing up every day. In order to simplify the mentioned research a new method was introduced to determine progress and end point in transesterification of sunflower oil to biodiesel (methyl esters) by the use of physical property variation during reaction. This method can be replaced by expensive and time-consuming, quantitative analysis stage. In the present work first transesterification of sunflower oil at 65 °C with MeOH to oil molar ratio of 6:1 and 1 wt.% of KOH as catalyst under vigorous mixing at different durations was carried out to determine how conversion and physical properties change. It was concluded that this reaction proceeded over 90% in 5 min and most of the changes occurred in this short period. In the second step, to verify physical properties variation in all ranges, six blends of produced biodiesel and sunflower oil were prepared in different wt.%, as incomplete reaction mixture. Finally appropriate functions were fitted on the extracted data and were evaluated. Refractive index and specific gravity were selected as good physical properties to predict reaction progress.     

Proficiency test on the determination of mineral oil in sunflower oil

Following the discovery of mineral oil contamination of Ukrainian sunflower oil in April 2008, the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC) was requested by the Directorate General Health and Consumers (DG SANCO) to organise a proficiency test on the determination of mineral oil in sunflower oil. The aim of this test was to evaluate the comparability of analysis results gained by laboratories in the EU and the Ukraine. The organisation of the study and the evaluation of the results were done in accordance with “The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories” and ISO Guide 43. Altogether 62 laboratories from 19 EU member states, Switzerland and the Ukraine subscribed for participation in the study. Four test samples at concentration levels between about 100 and 350 mg/kg, comprising contaminated crude sunflower oil, contaminated refined sunflower oil, and spiked sunflower oil, and a solution of mineral oil in n‐heptane were dispatched to the participants. The participants were asked to determine the mineral oil content of the test samples by application of their in‐house analysis methods. In total, 55 sets of results were reported to the organisers of the study. The performance of laboratories was expressed by z‐scores for the oil samples and by relative bias for the mineral oil solution in n‐heptane. The percentage of successful laboratories in the determination of the mineral oil content of sunflower oil was for all sunflower oil test materials about 80%.     

Influence of Zataria multiflora Boiss. essential oil on oxidative stability of sunflower oil

In this study, the influence of the application of 0.025%, 0.05% and 0.075% of Zataria multiflora Boiss. essential oil (EO) on oxidative stability of sunflower oil was examined and the EO was compared to butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) during storage at 37°C and 47°C. The main components of EO were identified as carvacrol (45.6%), p‐cymene (18.1%) and thymol (16.3%). Peroxide value (PV), anisidine value (AnV) and thiobarbituric acid (TBA) value measurement in sunflower oil showed that all concentrations of EO had a lower antioxidant effect in comparison to BHA and BHT. Samples supplemented with EO concentration of 0.075% were the most stable during storage at both temperatures (p<0.05). Furthermore, Totox value, antioxidant activity (AA), stabilization factor (F) and antioxidant power (AOP) determination confirmed efficacy of this EO as antioxidant in sunflower oil. EO also was able to reduce the stable 2,2‐diphenyl‐1‐picrylhydrazyl free radical (DPPH ^. ) with a 50% inhibition concentration (IC₅₀) of 34.3 ± 0.8 µg/mL. The results indicate that EO could be used as a natural antioxidant in oils for food uses.     

Transesterification of sunflower oil in microchannels with circular obstructions

The present paper studied numerical and experimentally the transesterification reaction between sunflower oil and ethanol with NaO H catalyst in microchannels with circular obstructions. The micromixer design influence on fluid mixing and oil conversion was investigated for a range of operating conditions: Reynolds number(Re = 0.1–100),Temperature(25–75 °C), ethanol/oil molar ratio(6-12), and catalyst concentration(0.75 wt%–1.25 wt%), using three microchannel configurations(Length = 35 mm; Width = 1500 μm; Height = 200 μm): T-shape – channel without obstructions; MCO – channel with 3 obstructions ensemble – equally disposed over longitudinal length;MWO – channel with 7 obstructions ensemble. The MCO micromixer was based on literature work, and the MWO is a totally new micromixer design. Experimental tests were conducted in similar conditions in microreactors using these micromixers(Length = 411 mm) made of polydimethylsiloxane. The MCO configuration presented the highest performance(mixing index of 0.80 at Re = 100), oil conversion of 81.13% at 75 °C, molar ratio of 9 and catalyst concentration of 1%. Experimental results showed high conversions for MCO and MWO configurations(99.99%) at 50 °C, molar ratio of 9 and catalyst concentration of 1%, with a residence time of 12 s.     

A kinetic study of the esterification of free fatty acids (FFA) in sunflower oil

The kinetics of the esterification of free fatty acids (FFA) in sunflower oil with methanol in the presence of sulphuric acid at concentrations of 5 and 10 wt% relative to free acids as catalyst and methanol/oleic acid mole ratios from 10:1 to 80:1 was studied. The experimental results were found to fit a first-order kinetic law for the forward reaction and a second-order one for the reverse reaction.The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. The energy of activation for the forward reaction decreased with increasing catalyst concentration from 50 745 to 44 559 J/mol.Based on the experimental results, a methanol/oleic acid mole ratio of 60:1, a catalyst (sulphuric acid) concentration of 5 wt% and a temperature of 60 °C provided a final acid value for the oil lower than 1 mg KOH/g oil within 120 min. This is a widely endorsed limit for efficient separation of glycerin and biodiesel during production of the latter.     

正庚烷在Pt/SAPO-41上异构化性能研究

以正庚烷为模型化合物,在连续微型反应装置上考察了Pt改性后的Pt/SAPO-41催化剂的异构化反应性能,探讨了工艺条件对异构化产物分布的影响。结果表明:Pt最佳负载量为0.55%;Pt/SAPO-41最佳工艺参数为温度400℃、压力为1.5MPa、液态空速为1.0h-1、VH2/Vn-heptane为600∶1;最佳条件下正庚烷转化率、C5+液收率,异构烃类和芳烃的选择性分别为79.82%,67.63%,71.44%和2.72%,且该催化剂具有良好的稳定性。     

NiMo/SAPO-11催化剂上正辛烷的异构化性能

以正辛烷为模型化合物,在连续微型反应装置上考察了金属Ni和Mo改性后的NiMo/SAPO-11催化剂的异构化和芳构化的反应性能,探讨了工艺条件对异构化产物分布的影响。结果表明:改性后的NiMo/SAPO-11催化剂在温度为400℃、压力为2.0MPa、液态空速为1.0h-1、VH2∶Vn.octane为400∶1的反应条件下反应性能较好,正辛烷的转化率、C5 液体产物收率,异构化和芳构化产物的选择性分别为69.80%、56.95%、79.73%、1.29%。     

正辛烯在CoMo/SAPO-11催化剂上的异构化反应性能

以正辛烯为模型化合物,在连续微型反应装置上考察了金属Co和Mo改性后的CoMo/SAPO-11催化剂的异构化的反应性能,探讨了工艺条件对异构化产物分布的影响。结果表明:改性后的Co-Mo/SAPO-11催化剂在温度为360℃、液态空速为1.0h-1、压力0.6MPa的反应条件下反应性能较好,此时的正辛烯的转化率、C5 液体产物收率都较高。     

Life Cycle Assessment (LCA) of the biofuel production process from sunflower oil, rapeseed oil and soybean oil

Once ratified the Kyoto protocol, Spain arises the great challenge of reducing the emissions of greenhouse gases. Among the measures proposed is the introduction of biofuels in the market, both for the transport sector and for the production of heat. This paper compares the environmental impact from the production of biofuels whose origin is the oil obtained from sunflower, rapeseed and soybeans. The environmental impact of each production is performed by applying the methodology of life cycle analysis (LCA). The categories where you get a greater impact are land use, fossil fuels, carcinogens, inorganic respiratory and climate change. The cause is mainly due to the processes of seed production. We have also found a significant impact on the drying and preparation processes of the seed as well as the crude soybean oil extracting process. Moreover as the LCA shows production of rapeseed and sunflower has a positive contribution to climate change.     

Transesterification of sunflower oil catalyzed by flyash-based solid catalysts

Flyash-based base catalyst was used in the transesterification of sunflower oil with methanol to methyl esters in a heterogeneous manner. Catalyst preparation variables such as, the KNO₃ loading amount and calcination temperature were optimized. The catalysts were characterized by powder XRD. The catalyst prepared by loading of 5 wt.% KNO₃ on flyash followed by its calcination at 773 K has exhibited maximum oil conversion (87.5 wt.%). The influence of various reaction parameters such as % catalyst loading, methanol to oil molar ratio, reaction time, temperature, reusability of the catalyst on the catalytic activity was investigated. K₂O derived from KNO₃ might be an essential component in the catalyst for its efficiency.     

Modification of polycaprolactone-styrene-vinyl trimethoxysilane terpolymer with sunflower oil for coating purposes

Polycaprolactone-styrene-vinyl trimethoxysilane terpolymer was prepared and then modified with sunflower oil partial glyceride (SFOPG) via a sol–gel method for use as a binder in coating applications. Therefore, a vinyl-functionalized polyester-based macromonomer (HPCL) was prepared via ring-opening polymerization of ?-caprolactone (CL) using 2-hydroxyethyl methacrylate (HEMA) followed by copolymerization with styrene (St) and vinyl trimethoxysilane (VTMS) to yield a terpolymer (HPCL-St-VTMS). The terpolymer was characterized by FTIR, GPC and ¹H NMR. To overcome the fact that the cured film of HPCL-St-VTMS was slightly soft, SFOPG was used as a modifier and was inserted to the structure via a sol–gel reaction between the hydroxyl groups and methoxy silane moieties of the terpolymer. After this modification, the softness disappeared. Nanosize inorganic domains were observed in the SEM image. Thermal analyses of the resulting cross-linked film of SFOM-HPCL-St-VTMS were performed with DSC and TGA. SFOM-HPCL-St-VTMS, which does not melt, resulted in a higher char yield and decomposition temperature at 5% weight loss compared to the unmodified HPCL-St-VTMS film. An evaluation of the film properties indicated that SFOM-HPCL-St-VTMS can be used as a coating material.     

Phase behavior of sunflower oil and soybean oil in propane and sulphur hexafluoride

Phase equilibria of sunflower and soybean oils in propane and sulphur hexafluoride (SF₆) have been investigated. The phase behavior of sunflower oil-propane and soybean oil-propane systems has been studied using high-pressure variable-volume cell. For both systems, the transition of the two-phase system to one-phase system was observed visually at 25 °C and 40 °C and at different system compositions generally in the range of 0.2-0.7 weight fraction of propane.Furthermore, high-pressure vapor-liquid phase equilibrium data (P-T-x-y) for the sunflower oil-SF₆ and soybean oil-SF₆ systems have been measured at temperatures of 25 °C and 40 °C and pressures from 10 bar to 500 bar using a static-analytic method. For the above mentioned systems with SF₆ the tree phase region was observed at pressures near the phase transition of SF₆ from vapor to liquid phase. Additionally, phase inversion for both investigated systems was recorded, as well.     

Effect of metal content on the behavior of Pt/SAPO-31 catalysts in the hydroconversion of sunflower oil

It is shown that catalysts based on Pt/SAPO-31 can be used for the single-stage conversion (in contrast to the two-stage commercial process) of vegetable oil into waxy diesel fuel components. The effect of the content of metal (0.5–2 wt % Pt) in the catalyst on its physicochemical and catalytic properties is studied. It is found that regardless of the platinum content, the activity of the catalysts diminishes during the reaction, as is indicated by a drop in their isomerization ability and the presence of oxygen-containing compounds in the reaction products. The physicochemical properties of Pt/SAPO-31 catalysts are studied via the IR spectroscopy of adsorbed pyridine, hydrogen chemisorption, and transmission electron microscopy. It is shown that the catalytic degradation is caused by the poisoning of the acid sites and a reduction in the active surface area of the metallic component. Possible ways of improving the on-stream stability of Pt/SAPO-31 samples in the hydroconversion of vegetable oil are described.