Homogeneous Alkaline Catalyst Research Articles

Sodium Glyceroxide: An Efficient Homogeneous Alkaline Catalyst for Biodiesel Synthesis

Biodiesel is obtained from the alcoholysis of triglycerides and has been used as a renewable alternative to diesel. Though the methanolysis of triglycerides in the presence of MeONa catalyst has been widely used, searching for alternatives that may improve the competitiveness of the production chain is still a challenge. The aim of this work was to evaluate sodium glyceroxide as a catalyst in the methanolysis of soy oil. Sodium glyceroxide was obtained from glycerol and NaOH in ethanol, and characterized by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD) and, Fourier transform infrared (FTIR) spectroscopy. The transesterification reaction was optimized after two sets of experiments based on the Doehlert matrix experimental design. In the first one, the influence of the molar ratio of methanol/triglyceride, and the amount of catalyst (m/m with respect to the triglyceride) were studied. In the second set, the temperature, and the reaction time were studied. The best conditions were found as 12:1 molar ratio, 2% of catalyst, 50 ºC, and 60 min. The conditions were applied in the transesterification of canola and sunflower oils, and tallow. All the biodiesels were obtained with an ester content superior to 98%, free from methanol and triglycerides. Specific mass, viscosity, and pour point were determined and met the international specifications.

A New Approach for Synthesizing Fatty Acid Esters from Linoleic-Type Vegetable Oil

Countries around the world recognize the numerous social, economic and environmental advantages of promoting liquid biofuels. They invest in its development and introduce tax incentives for its manufacture and tariffs of production regulation. In most studies, the process of synthesizing fatty acid esters takes a long time from 1 to 8 h. In this work, the synthesis of fatty acid esters was carried out in the range of volumetric ratios of ethanol to linoleic type oil in order to increase the kinetics of the process. The main parameters of the synthesis were studied by use of magnetic stirred tank reactors in a parallel reactor system, H.E.L. The synthesis was carried out in the presence of a homogeneous alkaline catalyst. The volumetric ratio of ethanol to oil was maintained at 1:1, 2:1, 3:1, 4:1 and 5:1. The amount of catalyst added to the reaction mixture ranged from 0.25 to 2.5% by the weight of the reaction alcohol. The dryness of ethanol varied from 91 to 99%. Effective process conditions have been established to reduce the reaction time from 2.5 h to 5 min while maintaining a high degree of conversion. The results obtained during the study suggest the possibility of using a continuous reactor to produce fatty acid esters from linoleic raw materials containing up to 16% of free fatty acids. This also means the possibility of using second generation biofuel feedstock.

Utilization of Waste Tobacco (Nicotiana Tabacum) Post-Harvest as an Alternative Biodiesel

The aims of this research is process into biodiesel. Biodiesel is produced using transesterification reactions with variations of tempetature. Tobacco seed oil is extracted to obtain edible oils as biodiesel. The content of free fatty acid (FFA) in edible oils should be minimized to obtain a high yield of transesterification. The catalyst used in converting edible oils into biodiesel is homogeneous alkaline catalyst. Biodiesel with the higest yield from transesterification reactions with a temperature of 70 oC. Biodiesel was characterized the functional group and phsycal properties including density and viscosity

DBU-assisted expeditious synthesis of highly stable IL@ZIFs intergrowth composite: A nanocatalyst for EMC production

Methyl ethyl carbonate (EMC) is the primary raw material for the electrolyte of lithium-ion batteries. It is mainly prepared by the transesterification reaction of dimethyl carbonate (DMC) and EtOH. However, homogeneous alkaline catalysts such as sodium alcohol commonly used in industry are easy to deactivate and challenging to separate and recover.Therefore, the alkaline ionic liquid decorated zeolitic imidazolate frameworks (IL@ZIFs) heterogeneous catalysts were prepared using a simple method with DBU as an inducer. In the synthetic route of IL@ZIFs, the ligand of ZIFs can form an ionic liquid with DBU, and deprotonated ligands will rapidly coordinate with metal ions at room temperature. The DBU can also play the structural guidance and stabilizer, which is conducive to the rapid and effective preparation of ZIFs materials. Meanwhile, the DBU, which has a large molecular diameter, will be trapped in the pore cage and can combine with other protic materials (imidazole, triazole, 2-methylimidazole, phenol, etc.) to form alkaline ionic liquids. The prepared DBU-IL@ZIFs were used as heterogeneous catalysts for synthesizing EMC by transesterification reaction. The DBU-PO@ZIF-8 composite with phenol as anion has better catalytic activity. Under the appropriate reaction conditions, the yield of EMC can reach 55.7% with high selectivity of 94.7%.The catalytic mechanism of DBU-PO@ZIF-8 in the transesterification reaction was also explored and revealed.

Biodiesel produced using potassium methoxide homogeneous alkaline catalyst: effects of various factors on soap formation

Biodiesel produced using potassium methoxide homogeneous alkaline catalyst: effects of various factors on soap formation

Effects of Alkaline Metals on the Reactivity of the Carbon Structure after Partial Supercritical Water Gasification of Coal

Conversion of coal, biomass, and organic waste to combustible gases H2 and CH4 in supercritical water (SCW) is an economically and environmentally favored technology. Homogeneous alkaline catalysts are commonly added to achieve high conversion efficiency, as alkalis are believed to accelerate the gasification of aromatic structures, which is the bottleneck of the whole gasification process. Nevertheless, the mechanism of how alkali metals influence the reaction of aromatic structures is still not acknowledged clearly. In this work, different pretreatments of the high-alkali metal content Zhundong coal are taken as the object to study the effect of naturally present and artificial additive alkali metals on the microcrystalline carbon structure and their reactivity with H2O during the supercritical water gasification (SCWG) process. XRD analysis was applied to reveal that alkali metals inhibit the growth of graphite-like structures during SCWG. Subsequently, the separated smaller sized aromatic structures are indicated by calculating the Fukui function values of peripheral carbon atoms to exhibit higher reactivity with H2O and the free radicals in SCW. Finally, the existence of alkali metals is proven to promote the strong chemisorption of H2O on carbon structures, which is the premise of carbon abstraction of the aromatics, via thermogravimetric analysis. The influence of different reactors and SCW is also involved in the discussion. This work is prospective for optimal utilization of the homogeneous catalysts and developing innovative catalysts.

A novel method for the synthesis of biodiesel as an eco-friendly and sustainable fuel

Biodiesel is a green diesel fuel that is synthesized via the transesterification reaction of plant oils or animal fats with light alcohols, mainly methanol, in the presence of commonly homogeneous alkaline catalysts. One way to make the biodiesel synthesis process more eco-friendly is the use of heterogeneous catalysts as they are reusable. But with these catalysts, the transesterification reaction mixture will be a three-phase mixture containing methanol, oil and catalyst that leads to long reaction times and high process costs. In this study, the ultrasound waves were used to synthesis of the biodiesel from the Jatropha oil in the presence of CaO as a heterogeneous catalyst. The effect of two different co-solvents (acetone & hexane) on improving the homogeneity of the reaction mixture and therefore to enhance the conversion yield of the oil to biodiesel was considered. Experiments were carried out by a probe type ultrasonic instrument at an output power of 200 W and frequency of 20 kHz. The results showed that both of the considered co-solvents had positive effect on developing the conversion yield and the acetone was the more efficient one due to its moderate polarity, which could improve the miscibility of the oil with the methanol. A biodiesel sample with a conversion yield of 90.33% was synthesized under optimal operating conditions including 25% v/v acetone to methanol, 12:1 methanol to oil molar ratio, 4% w/w catalyst to oil, 55°C reaction temperature and 60 min reaction time. Hnmr and densitometry were used to determine the percentage of the synthesized biodiesel samples. Also, some of the physicochemical properties of the synthesized biodiesel were analyzed, which were in accordance with the ASTM and EN standards.

Transesterification of Palm‐based Methyl Palmitate into Esteramine Catalyzed by Calcium Oxide Catalyst

AbstractThe technology for transesterification reactions between methyl esters and alcohols is well established by using classical homogeneous alkaline catalysts, which provide high conversion of methyl esters to specialty or nonindigenous esters. However, in certain products where the purity of the esters is of concern, the removal of homogeneous catalysts after the completion of the reaction is a challenge in terms of production cost and water footprint. Therefore, a study to investigate the potential of heterogeneous catalysts was conducted on reactions between methyl palmitate and triethanolamine. The degree of basicity and active surface area of calcium oxide (CaO), zinc oxide (ZnO), and magnesium oxide (MgO) were first characterized by using temperature‐programmed desorption (TPD‐CO2) and Brunauere–Emmett–Teller (BET), respectively. Among the metal oxides investigated, the CaO catalyst showed the best catalytic activity toward the transesterification process as it gave the highest conversion of methyl palmitate and yielded fatty esteramine compositions similar to the conventional homogeneous catalyst. The optimum transesterification condition by using the CaO catalyst utilized a lower vacuum system of approximately 200 mbar, which could minimize a considerable amount of energy consumption. Furthermore, low CaO dosage of 0.1% was able to give a conversion of 94.5% methyl ester and formed esteramine at 170 °C for 2 h. Therefore, the production of esterquats from esteramine may become more economically feasible through the methyl ester route by using the CaO catalyst, which can be recycled three times.

Light biodiesel from macaúba and palm kernel: Properties of their blends with fossil kerosene in the perspective of an alternative aviation fuel

Oil either from macaúba (Acrocomia aculeate) and palm (Elaeis guineensis) fruit kernel was transesterified with methanol through the classical reaction with homogeneous alkaline catalyst. The produced fatty acid methyl esters (FAME) were further fractionated via atmospheric distillation as a step to obtain enriched fractions in short-molecular chain esters, ranging from C8 to C14, in a perspective to be blended with the conventional mineral jet fuel (Jet A-1). In this report, such blends of light biodiesels with Jet A-1 kerosene are described for their density, distillation fractions according to the temperature, structure changes under thermal treatments, by thermogravimetry and differential calorimetry analyses, freezing point, flash point, and calorific value. The blends corresponding to 5, 10 and 20 vol% in enriched short-chain esters with kerosene revealed values well within the recommended limits by the ASTM D1655. Light biodiesels, which are rich in lauric acid (C12:0) methyl esters are suitable to be blended with the Jet A-1 kerosene up to at least 5 vol%. Those blends could produce virtually very similar fuels, regarding the main technical standard properties, to the conventional fossil kerosene for jet engines, particularly concerning the moisture content, the density, its behavior in distillation and the flash point.

The Formation of Glycerol Oligomers with Two New Types of End Groups in the Presence of a Homogeneous Alkaline Catalyst.

The purpose of this work was to synthesize and characterize oligoglycerols with the chains of more than four repeating units. Those oligoglycerols may have some interesting applications, among others, as polyoxyalkylation starters. The glycerol oligomerization process was carried out during 12 h, at 230 °C, under the pressure of 0.4 bar, with the use of sodium carbonate as a homogeneous basic catalyst; various concentrations of the catalyst in the reaction medium were used. The reaction products were analyzed with the use of direct infusion electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (13C NMR) and Fourier transform infrared spectroscopy (FTIR) techniques. Based on the analytical findings, the compositions of the obtained product mixtures and the structures of oligoglycerols present in individual fractions were determined. The effect of catalyst concentration on the composition of the post-reaction mixture was observed. Moreover, in addition to the conventional linear oligomers (α,α-oligoglycerols), two new types of the oligomers were for the first time detected in the post-reaction mixture: one with two hydroxyl groups and the other with a carboxylate group at the α-carbon atom.

Use of activated carbons as catalyst supports for biodiesel production

The traditional method of biodiesel production is based on the transesterification of triglycerides using an alkaline catalyst dissolved in methanol. The aim of this study was to replace a homogeneous alkaline catalyst with a heterogeneous catalyst on the carbon support. The use of a carbon enables the catalyst to be reusable in the production process, eliminates the formation of soaps and increases the glycerol purity. Fatty acid methyl esters were obtained from the transesterification of corn oil using KOH supported on activated carbon (KOH/AC). The effect of the molar ratio of methanol to oil, reaction time and catalyst amount were used to optimize the transesterification reaction. The optimum condition for waste corn oil transesterification to methyl ester was obtained below 0.75 wt.% catalyst amount. The yield was up to 92 wt.% at 62.5 °C, 1 h reaction time and 3:1 methanol-to-oil ratio. This study demonstrated that the transesterification of the waste corn oil using methanol can be effectively catalyzed by the developed catalyst.

The Effect of Acetone Amount Ratio as Co-Solvent to Methanol in Transesterification Reaction of Waste Cooking Oil

The production of biodiesel from waste cooking oil by transesterification reaction using acetone as co-solvent has been carried out. This research studied the optimal amount ratio of acetone as co-solvent to methanol in the transesterification process using homogeneous alkaline catalyst KOH 1% (w/w) of waste cooking oil at room temperature for 15 minutes of reaction time. Mole ratio of waste cooking oil to methanol is 1:12. Acetone was added as co-solvent in varied amount ratio to methanol are 1:4, 1:2, and 1:1, respectively. The results of fatty acid methyl esters (FAME) were analysed using GC-MS instrument. The results showed that the optimal ratio is 1:4 with 99.93% of FAME yield.

Single-phase transesterification of palm oil in the presence of methylethylketone - a study on intrinsic reaction kinetics -

Single-phase transesterification of palm oil with methanol catalyzed by homogeneous alkaline catalyst was carried out in a laboratory scale batch reactor at 298, 308 and 323 K in the presence of methylethylketone (MEK) as a co-solvent. Most of the previous research studies on single-phase transesterification by using a co-solvent were conducted to obtain higher reaction rates than two-phase. In the present study, the authors targeted to investigate the intrinsic reaction kinetics of transesterification of oil with methanol catalyzed by homogeneous alkaline. The reaction experiment was carried out at 0.1, 0.2 and 0.6 mol/L of palm oil initial concentration. The transesterification reaction rate constant behaved in a strange manner with the initial oil concentration: the rate constant increased with a decrease in the initial oil concentration. This may be attributed to size change of palm oil molecule with MEK concentration in palm oil-methanol-MEK system.

ПОЛУЧЕНИЕ БИОДИЗЕЛЬНОГО ТОПЛИВА ИЗ НЕПИЩЕВОГО РАСТИТЕЛЬНОГО СЫРЬЯ

The aim of the research is to improve the properties of diesel fuel due to the use of biofuels as addi-tivestha. It is especially important while operating the farm equipment. Biodiesel was obtained by the reaction of transesterification in the presence of a homogeneous alka-line catalyst. Synthesis of biofuels was conducted by the innovative technology with the use of the apparatus with a rotating electromagnetic field students leading to the intensification and acceleration of the chemical reaction. Synthesized fuel was blended with petroleum diesel fuel and analysed according to physicochemi-cal parameters (density, kinematic viscosity, lubricity, etc.). Oil diesel fuel 5, 10, 20, 40, 100% and supple-ment based on microalga chlorella were used. The improved technology of cultivation of Chlorella vulgaris microalgae IGF No. C-111 consisting of four stages and a method for extracting lipids for subsequent use as raw material for the synthesis of biofu-els and bioadditives were developed. The physico-chemical prosperities of the obtained biodiesel are not inferior to diesel fuel and even surpass it in environmental and operational prosperities. Biofuels as a supplement must be used in order to improve the operational and environmental prop-erties of diesel fuels. The most promising raw material for biodiesel is a non-food renewable resource of highly productive oil plants - microalgae.

Characteristics of Block Copolymers of Methyl Oxirane and Oxirane Derivatives of 2-Ethylhexanol as Obtained with KOH and Dimetalcyanide Type Catalyst

Abstract Two series of block copolymers of methyloxirane and oxirane, derivatives of 2-ethylhexanol, were obtained with the use of KOH as a conventional homogeneous alkaline catalyst and a coordinative dimetalcyanide catalyst (DMC), respectively. The DMC type catalyst showed much higher kinetic activities and its reaction exhibited a narrower distribution of homologues, as compared with those obtained in the presence of KOH. The thermogravimetric technique was proposed for the characterization of the fractional content of products. The pluming phenomenon and VOCs content were discussed as a practical aspect of the differences in fractional compositions of the products examined.

Use of a Corrugated Plates Heat Exchanger Reactor for Obtaining Biodiesel with Very High Productivity

A corrugated plates heat exchanger reactor showing very high productivity in the transesterification of soybean oil with methanol, in the presence of a homogeneous alkaline catalyst (KOH, sodium methoxide), has recently been tested. The reactor is a small size corrugated plates heat exchanger having a low distance between the plates of 1.5−2 mm. A surprising behavior has been observed according to which the conversion to biodiesel increases by increasing the overall flow rates. This can be explained by examining the fluid dynamic behavior of the system with a step test, at different flow rates, made on single-phase liquid fluid. The observed experimental data for the higher flow rates can roughly be approximated to a plug flow behavior despite the very low Reynolds numbers. This is due to the intervention of a very active micromixing. In this reactor the local turbulence favors the mixing of two immiscible liquid reactants approaching, in the case of biodiesel production, the chemical regime. In this work we have shown that by using corrugated plates heat exchanger reactors (CP-HEX reactors) of opportune geometry we can largely intensify the process of biodiesel production. The micromixing intensity in these reactors is very high, favoring the contact between immiscible reagents such as methanol and oil. Therefore, the reactor could generally also be used for other liquid−liquid reactions and more advantageously for very exothermic or endothermic reactions for the great efficiency of the plates exchangers in removing or supplying heat to the reaction interspace.

Biodiesel: visão crítica do status atual e perspectivas na academia e na indústria

This article presents a bibliographic review of research carried out on different alternative processes for biodiesel production. The supercritical and subcritical (non catalytic) reaction conditions, the use of solid basic, solid acid and other heterogeneous catalysts, including the use of immobilized enzymes and whole-cell catalysts are also critically compared with the traditional homogeneous alkaline or acid catalysts that are common on industrial applications. Advantages and limitations of all these processes for the transference from the laboratory to the industry are discussed. A correlation of the chemical composition with the quality parameters of the produced biodiesel is done with aim to stablish adequate procedures for the right selection of the raw-material. Castor bean oil is used as an example of inappropriate oil in order to produce a B100 that fulfill all the international physico-chemical quality standards. In this article are presented research results to adequate the values of viscosity, density and iodine number of the castor and soybean biodiesel to the international standard limits by means blending these both biodiesels at the right ratio.

Synthesis of biodiesel via homogeneous Lewis acid catalyst

Nowadays, most biodiesel (fatty acids methyl esters, FAME) is produced by the transesterification of triglycerides (TG) of refined/edible type oils using methanol and an homogeneous alkaline catalyst. However, production costs are still rather high compared with the ones of petroleum-based diesel fuel. To lower costs and make biodiesel competitive less-expensive feedstocks such as waste fats or non-edible type oils could be used. The use of homogeneous alkaline catalysts in the transesterification of such types of fats and oils poses great difficulties due to the presence of large amounts of free fatty acids (FFA). This paper studies the use of carboxylic salts as a possible alternative, because these catalysts are active also in the presence of high FFA concentrations. The most active catalyst (Cd, Mn, Pb, Zn carboxylic salts) have been individuated and a correlation of the activities with the cation acidity has been found.