• Energy Research

Abstract The use of MgO impregnated with KOH as heterogeneous catalysts for the transesterification of mutton fat with methanol has been evaluated. The mutton fat (fat) with methanol (1:22 M ratio) at 65 °C showed > 98% conversion to biodiesel with 4 wt% of MgO–KOH-20 1 (MgO impregnated with 20 wt% of KOH) in 20 min. The reaction conditions optimized were; the amount of KOH impregnation (5–20 wt%), the amount of catalyst (1.5–4 wt%, catalyst/fat), the reaction temperature (45–65 °C), fat to methanol molar ratio (1:11–1:22) and the effect of addition of water/oleic acid/palmitic acid (upto 1 wt%). Although, transesterification of fresh fat (moisture content 0.02 wt% and free fatty acids 0.002 wt%) with methanol in the presence of KOH (homogenous catalyst) resulted in the complete conversion to biodiesel, but in the presence of additional 1 wt% of either free fatty acid or moisture content, formation of soap was observed. The MgO–KOH-20 catalyst was found to tolerate additional 1 wt% of either the moisture or FFAs in the fat.

Abstract Lithium doped ceria loaded SBA-15 has been synthesised under normal atmospheric condition (without using hydrothermal treatment) and following wet impregnation route. The catalyst has been characterised by using different techniques viz., BET method for surface area measurements, FE-SEM for surface morphology study, XPS for the determination of catalyst composition and element oxidation state. The catalyst was found to possess both acidic and basic sites and hence, successfully employed for the simultaneous esterification and transesterification of waste cottonseed oil. Under optimized reaction conditions of catalyst concentration 10 wt%, methanol to oil molar ratio of 40:1 at 65 °C, the catalyst was able to give >98% fatty acid methyl ester yield within 4 h of reaction time. The catalyst was recovered and reused during 5 successive runs without any significant loss of activity. The activation energy (Ea) for the reaction was found to be 57.7 kJ mol−1, while ΔH‡, ΔG‡ and ΔS‡ were found to be 59.4 kJ mol−1, +95.9 kJ mol−1and - 0.108 kJ mol−1, respectively. On the basis of thermodynamic parameters, the reaction is expected to be endothermic, non spontaneous and following an associative pathway.

Abstract Present work demonstrates an easy route by sol-gel method, without using any template, for the synthesis of flower shaped tungsten (W) supported TiO2/SiO2catalyst for the triglyceride transesterification. The structure of the catalyst was established by powder X-ray diffraction and surface morphology and particle size by field emission scanning and high resolution transmission electron microscopy studies, respectively. The oxidation state of tungsten by X-ray photoelectron spectroscopy was found to be +6. Under the optimized reaction conditions of 5 wt% of 20-W/TiO2/SiO2-700 catalyst, 30:1 methanol to oil molar ratio and 65 °C reaction temperature, more than 98% fatty acid ethyl ester yield was obtained in 4 h. The kinetic and thermodynamic parameter of the reaction was also evaluated following the pseudo-first order equation. The catalyst was recycled in four consecutive runs and total metal contents in biodiesel was observed

Abstract To develop heterogeneous and reusable catalyst for the esterification of fatty acids, in presence of triglycerides, sulfate species has been incorporated over Ce/ZrO2–TiO2 support. The catalyst activity was found to be a function of its Bronsted acidic sites which in turn depends on the cerium concentration in catalyst. The esterification of oleic acid with methanol or ethanol in presence of prepared catalyst has followed the first order kinetics and Koros–Nowak test has demonstrated that reaction rates are independent from diffusion limitations. An increase in acid or alcohol alkyl chain length (steric factor) was found to show negative effect on the esterification activity of catalyst. Although, the catalyst was able to catalyze the esterification even in presence of up to 12 wt% moisture (with respect to fatty acids), however, a decrease in turn over frequency (TOF) was observed. The catalyst has shown excellent stability as negligible sulfate leaching was observed and recovered catalyst was reused in five successive runs without significant loss in activity. Even in presence of triglyceride (vegetable oil) the catalyst was able to convert >98% free fatty acids into respective esters. The esterified oils were fruitfully employed, without any pre-neutralization and water washing, in homogeneous alkali catalyzed transesterification to achieve >98% fatty acid methyl ester (FAME) yield.

Abstract 5-Na/ZnO loaded SBA-15 has been prepared by one-pot method in atmospheric conditions (without employing hydrothermal treatment) and following wet impregnation method. The prepared catalyst was characterised by using several techniques viz., BET method for determination of surface area, FE-SEM for morphology of catalyst, XPS study to determine the oxidation state of constituent elements. The catalyst was utilised for transesterification from virgin cotton seed oil and the catalyst activity was dependant on its basic strength. Under optimal reaction conditions of catalyst amount 12 wt%, methanol to oil molar ratio of 24:1 at reaction temperature of 65 °C, the prepared catalyst yielded > 98% fatty acid methyl ester in 4 h of reaction duration. The catalyst was able to yield conversion level as good as ∼74% even in 5th cycle after regeneration. Leaching of

In order to study the effect of metal ions on lipase activity, hydrolytic and transesterification activities of Candida rugosa lipase were investigated in presence of alkali (Na⁺ and K⁺), alkaline earth (Ca⁺² and Ba⁺²) and transition (Cr⁺³, Fe⁺³, Co⁺², Cu⁺² and Ni⁺²) metal ions. Maximum enhancement in hydrolytic activity of lipase was observed by Ca⁺², and in transesterification activity by Cr⁺³ and Co⁺². The kinetics of the lipase catalyzed transesterification (methanolysis and ethanolysis) reactions were also studied, and the activation energies of methanolysis and ethanolysis were reduced from 10.16 and 10.24 kcal mol⁻¹, respectively, to 5.41 and 7.55 kcal mol⁻¹, respectively, when reactions were performed in presence of Co⁺². Thus, in lipase catalyzed transesterification Cr⁺³ or Co⁺² could be added to the assay in order to produce the biodiesel in relatively shorter reaction duration.

Abstract Potassium impregnated mixed oxides of lanthanum and magnesium in 1:1 to 1:5 atomic ratios were prepared by co-precipitation at a constant pH. These were characterized by FEG–SEM–EDX, TEM, Powder XRD, Hammett indicators and acid/base titration and, were evaluated as heterogeneous catalysts for transesterification of used cotton seed oil with methanol. The optimized reaction conditions for the catalyst, prepared at pH 10 using 1:3 atomic ratio of lanthanum and magnesium, were the use of 1:54 molar ratio of oil to methanol and 5 wt.% of the catalyst at 65 °C that resulted into 96% conversion to biodiesel within 20 min. The catalyst showed tolerance of 1 wt.% of moisture. Concentration of potassium ions leached out from catalyst into biodiesel was within permissible limit of ASTM.

The work presented in current manuscript demonstrated the preparation of potassium ion impregnated calcium oxide in nano particle form and its application as solid catalyst for the transesterification of a variety of triglycerides. The catalyst was characterized by powder X-ray diffraction, scanning electron and transmission electron microscopic, BET surface area measurement, and Hammett indicator studies in order to establish the effect of K+ impregnation on catalyst structure, particle size, surface morphology, and basic strength. The catalyst prepared by impregnating a mass fraction of 3.5% K+ in CaO was found to exist as similar to 40 nm sized particles, and same was employed in present study as solid catalyst for the transesterification of a variety of feedstocks viz., mutton fat, soybean, virgin cotton seed, waste cotton seed, castor, karanja and jatropha oil. Under optimized conditions, K-CaO was found to yield 98 +/- 2% fatty acid methyl esters (FAMEs) from the employed feedstocks, and showed a high tolerance to the free fatty acid and moisture contents. A pseudo first order kinetic model was applied to evaluate the kinetic parameters and under optimized conditions first order rate constant and activation energy was found to be 0.062 mm(-1) and 54 kJ mol(-1), respectively. The Koros-Nowak criterion test has been employed to demonstrate that measured catalytic activity was independent of the influence of transport phenomenon. Finally, few physicochemical properties of the FAMEs prepared from waste cotton seed oil, karanj a oil and jatropha oils have been studied and compared with European standards. (C) 2012 Elsevier Ltd. All rights reserved.