Polyol-Derived Alkoxide/Hydroxide Base Catalysts I. Production

A metal methoxide is more expensive than a metal hydroxide and dissolves in methanol releasing a methoxide ion without producing water. The methoxide ion has a higher reaction rate making it more preferred for industrial biodiesel production. This study describes the preparation of alkoxide catalysts from metal hydroxides and non-volatile, non-toxic polyols. Heating aqueous solutions of metal hydroxides and different polyols (1,2-propanediol, 1,3-propanediol, glycerol, xylitol and sorbitol) under vacuum yielded polyol-derived alkoxide base catalysts (PDABC). Comparison of the drying process for respective sodium hydroxide-polyol combinations at two mole ratios of sodium hydroxide to polyol showed that drying at 2:1 mole ratio (metal hydroxide to polyol) was more efficient than that of 3:1. Dehydration of alkaline solutions containing three or more hydroxyl groups (glycerol, sorbitol and xylitol) was faster than drying similar solutions of diols. The empirical formula determined confirmed that the resulting powders contained mono-sodium substituted alkoxides at 1:1, 2:1 and 3:1 (sodium hydroxide: polyol) mole ratio. Fatty acid methyl esters were prepared from canola oil and methanol using glycerol sodium alkylate as a catalyst. The conversion yield of oil to methyl ester was greater than 99 %.     

离子型树脂催化酯交换反应的研究

一种线型强碱型阴离子型树脂与无机材料SiO2的共混物QAPPES/SiO2被制备了出来,作为催化剂应用于大豆油与甲醇的酯交换反应中,制备脂肪酸甲酯.实验结果表明,QAPPES/SiO2在较低的温度下对脂肪酸甘油酯与甲醇的酯交换反应表现出较高的催化活性:在快速的搅拌下,60℃、醇油体积比3:1、催化剂加入量与豆油加入量数值上的关系为1:4(质量/体积)、反应时间为8 h,在此条件下油脂的转化率可达到76%.不同因素对反应影响作用的大小依次为反应物醇油比(体积)>反应搅拌速度＞反应温度＞反应催化剂加入量＞反应时间.     

Transesterification of castor oil: Effect of the acid value and neutralization of the oil with glycerol

This paper evaluates the production of methyl esters from castor oil and methanol after neutralization of castor oil with glycerol. The reaction was carried out under atmospheric pressure and ambient temperature in a batch reactor, employing potassium hydroxide as catalyst. Results showed high yield of castor oil into methyl esters after neutralization of castor oil with glycerol. The highest yield observed was of 92.5% after 15 min of reaction. The best operating condition was obtained applying an alcohol to oil molar ratio of 6.0 and 0.5% w/w of catalyst.     

Utilization of waste cockle shell (Anadara granosa) in biodiesel production from palm olein: Optimization using response surface methodology

The cockle shell, which is available in abundance, has no any eminent use and is commonly regarded as a waste, was utilized as a source of calcium oxide in catalyzing a transesterification reaction to produce biodiesel (methyl esters). A central composite design (CCD) was used to optimize the two major influential reaction variables: catalyst and methanol amount towards purity and yield of methyl esters. The analysis of variance (ANOVA) indicated that the catalyst has a positive influence on purity but negative on the yield. Meanwhile, the methanol/oil mass ratio showed a positive effect on both purity and yield. Using CCD, the optimum reaction conditions were found to be 4.9 wt.% of catalyst and 0.54:1 methanol/oil mass ratio. The prepared catalyst was capable of being reused under the suggested optimal conditions.     

Production of Isopropyl and Methyl Esters from Yellow Mustard Oil/IPA Miscellas

Using an isopropyl alcohol (IPA):flour [volume:weight (ml:g)] ratio of 1.5:1 per stage of extraction resulted in an oil yield of 86.3%. The combined miscella (IPA + oil), which contained 90.6 wt% IPA, 9.8 wt% oil, and 2.1 wt% water, was used as a feedstock for biodiesel production by transesterification. Transesterification of the IPA/oil miscella dehydrated using adsorption on 4Å molecular sieves with 1.2 wt% (based on oil) potassium hydroxide for 2 h at 72 °C converted only 29% of the feed to esters. The addition of methanol (MeOH) resulted in an ester yield of 87%, consisting of 79% methyl ester and 7% isopropyl ester when starting with an IPA:oil:MeOH molar ratio of 146:1:30. By increasing the KOH catalyst to 3 wt%, the ester yield increased to 94%. To increase the ester yield, the miscella was pretreated with sulfuric acid. This resulted in a reduction of the IPA content, the removal of other impurities such as phospholipids, and reduction of the water mass fraction to less than 1%. When IPA was used as a cosolvent with methanol in the transesterification process, a very high ester conversion (>99%) was achieved. The biodiesel produced was compliant with ASTM standards, showing that IPA can be used as a solvent for oil extraction from yellow mustard flour.     

Roselle (Hibiscus sabdariffa L.) oil as an alternative feedstock for biodiesel production in Thailand

The production of biodiesel fuel from crude roselle oil was evaluated in this study. The process of alkali-catalyzed transesterification with methanol was carried out to examine the effects of reaction variables on the formation of methyl ester: variables which included methanol-to-oil molar ratios of 4:1-10:1, catalyst concentrations of 0.25-2.0% w/w of oil, reaction temperatures of 32-60 °C, and reaction times of 5-80 min. The methyl ester content from each reaction condition was analyzed by gas chromatography (GC), the optimum condition having been achieved at a methanol-to-oil molar ratio of 8:1, a catalyst concentration of 1.5% w/w of oil, a reaction temperature of 60 °C, and a reaction time of 60 min. The resultant methyl ester content of 99.4% w/w, plus all of the other measured properties of the roselle biodiesel, met the Thai biodiesel (B100) specifications and international standards EN 14214:2008 (E) and ASTM D 6751-07b, with the exception of a higher carbon residue and lower oxidation stability.     

Transesterification Catalysts from Iron Doped Hydrotalcite-like Precursors: Solid Bases for Biodiesel Production

Abstract Described are new solid base catalysts for transesterification of seed oil triglycerides to fatty acid methyl esters, a key step in biodiesel production. These were prepared by substituting Fe3+ ions substitute for a fraction of the Al3+ ions in the Mg/Al layered double hydroxide lattices of hydrotalcites (HTC) and calcining to give porous metal oxides (PMOs). These iron-doped PMOs are much stronger bases than those derived from undoped or Ga3+ doped HTCs and are effective catalysts for the methanol transesterification of triacetin (glycerol triacetate) and of soybean oil. Graphical Abstract New solid base catalysts for transesterification of seed oil triglycerides to fatty acid methyl esters, a key step in biodiesel production, were prepared by substituting Fe³⁺ for Al³⁺ cations in hydrotalcite (HTC) structures and calcining to give porous metal oxides.      

Determination of Acylglycerols and Glycerol in Castor:Soybean Biodiesel Blend Produced by a Base/Acid-Catalyzed Process

This paper describes the production of the methyl biodiesel blend of hydroxylated vegetable (castor oil) and soybean oils by a base/acid‐catalyzed process and the first simultaneous determination by gas chromatography of the levels of total and free glycerol, mono‐, di‐ and triacylglycerols based on the standard method ASTM D 6584. Best results were observed for transesterification carried out in 6:1 (methanol:oil), sodium hydroxide 1 % w/w at 60 °C for 1.5 h. The analytical method not only produced curves with good linearity, but also had a coefficient of determination (r²) above 0.997 and accuracy between 70 and 141 % at relative standard deviations (RSD) lower than 10 %. The matrix effect (ME) was investigated and only diolein was found to have a significant matrix effect. The method was robust when applied to different chemical compositions of biodiesel. Results showed that the acid value and the contents of mono‐, di‐, and triacylglycerols, total and free glycerol were within the limits set by standardized methods and that biodiesel may be produced from soybean and castor oil blends.     

Kinetics of sodium borohydride direct oxidation and oxygen reduction in sodium hydroxide electrolyte: Part II. O2 reduction

In order to mimic the operation of the air-cathode in a direct borohydride alkaline fuel cell, we studied the oxygen reduction reaction (ORR) in sodium hydroxide solution containing traces of borohydride. The activity of several ORR electrocatalysts, namely carbon-supported platinum, gold, silver and manganese oxide, has been investigated using slow-scan linear voltammetry. Whereas platinum is one of the best electrocatalyst in pure sodium hydroxide, none of the classical electrocatalysts: gold, silver and platinum, exhibit sufficient selectivity towards the ORR. When BH₄⁻ is present in solution, the potential taken by electrodes using such materials is a mixed potential, following the competition between the ORR and the NaBH₄ hydrolysis and/or oxidation. Conversely, manganese oxide-based electrocatalysts exhibit very interesting behaviour towards the ORR in alkaline medium; while their intrinsic ORR activity in pure sodium hydroxide is quite as good as that for platinum, they still display a remarkable selectivity for this reaction when the electrolyte contains traces of sodium borohydride.As a result, carbon-supported manganese oxide-based nanoparticles seem very interesting materials to be used in direct borohydride fuel cell.     

Transesterification of palm oil on KyMg1 − xZn1 + xO3 catalyst: Effect of Mg-Zn interaction

The Mg-Zn interaction effect of K_yMg_1 − xZn_1 + xO₃ heterogeneous type catalyst and its performance on transesterification of palm oil have been studied using the response surface methodology and the factorial design of experiments. The catalyst was synthesized using the co-precipitation method and the activity was assessed by transesterification of palm oil into fatty acid methyl esters. The ratio of the Mg/Zn metal interaction, temperature and time of calcination were found to have positive influence on the conversion of palm oil to fatty acid methyl ester (FAME) with the effect of metal to metal ratio and temperature of calcination being more significant. The catalytic activity was found to decrease at higher calcination temperature and the catalyst type K₂Mg_0.34Zn_1.66O₃ with Mg/Zn ratio of 4.81 gave FAME content of 73% at a catalyst loading of 1.404 wt.% of oil with molar ratio of methanol to oil being 6:1 at temperature of 150 °C in 6 h. A regression model was obtained to predict conversions to methyl esters as a function of metal interaction ratio, temperature of calcination and time. The observed activity of the synthesized catalyst was due to its synergetic structure and composition.