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Renewable biodiesel with a high content of n-C17 alkanes was prepared through the catalytic hydrodeoxygenation of oleic acid under optimum conditions of temperature, reaction time and weight percentage of Ni deposited in γ-Al2O3. The hydrotreated vegetable oil (HVO) was blended with petrodiesel (20 % and 40 % of HVO) to evaluate its behaviour in a diesel engine. Comparative studies of power and emission of atmospheric pollutants such as NOx, CO, HC and smoke were evaluated under prepared blends and petrodiesel. The presence of HVO biodiesel at full load generated a slight decrease in power compared to petrodiesel; however, the decrease in emission of pollutants when using the blends containing HVO was significant. In the case of 40 % HVO were able to reduce more of 20 % of CO and HC emissions, and more than 40 % reduction in smoke when compared with petrodiesel. The NOx emissions of the blends with HVO had a significant slightly decrease. Further, the properties of Ni/γ-Al2O3 catalysts are justified by the results of EDS characterization, surface area (SBET), XRD, XPS, HR-TEM and it's capacity to produce biodiesel. [ABSTRACT FROM AUTHOR]

To contribute to the search for an oxygen-free biodiesel from vegetable oil, a process based in the oleic acid hydrodeoxygenation over Ni/γ-Al2O3 catalysts was performed. In this work different wt % of Ni nanoparticles were prepared by wetness impregnation and tested as catalytic phases. Oleic acid was used as a model molecule for biodiesel production due to its high proportion in vegetable oils used in food and agro-industrial processes. A theoretical model to optimize yield of n-C17 was developed using size, distribution, and wt % of Ni nanoparticles (NPs) as additional factors besides operational conditions such as temperature and reaction time. These mathematical models related to response surfaces plots predict a higher yield of n-C17 when physical parameters of Ni NPs are suitable. It can be of particular interest that the model components have a high interaction with operation conditions for the n-C17 yields, with the size, distribution, and wt % of Ni NPs being the most significant. A combination of these factors statistically pointed out those conditions that create a maximum yield of alkanes; these proved to be affordable for producing biodiesel from this catalytic environmental process. [ABSTRACT FROM AUTHOR]

Abstract: Simple kinetic model is proposed for fitting experimental data of degradation and total organic carbon (mineralization) of phenol. Reaction rates analysis of phenol in water are employed to compare different photocatalysts under the same experimental conditions. The global photonic efficiency for degradation and mineralization of phenol ξ g, is calculated to facilitate comparison with other photocatalysts or experimental systems. Under identical conditions of catalyst loading, pH and phenol concentration the most of photocatalysts presented a global efficiency much lower than that for a TiO2 standard photocatalyst named Degussa P-25. However, two photocatalysts prepared by different methods showed approximately the same global efficiency than the commercial material. [Copyright &y& Elsevier]

The trans-esterification and esterification of waste vegetable oil mainly under sub-critical temperature of methanol in the presence of sulfonated char were achieved. The carbonaceous materials were analyzed by means of various physical and chemical techniques such as Raman spectroscopy, X-ray diffractometry, temperature programmed desorption and X-ray photoelectrons spectroscopy. The carbon-based large-acidity catalyst showed good chemical and thermal properties and a high performance in the production of methyl esters from waste vegetable oil, which was easily separated from the liquid mixture. A temperature of 210°C, reaction time of 20 min and a catalyst amount of 0.03 g were the optimal experimental conditions for the trans-esterification of the vegetable oil with methanol giving a conversion to triglycerides of 96.5% according to the response surface methodology. The design of experiments type Box-Behnken was successfully applied to study effects of the parameters in the production of biodiesel and it presented optimal conditions for maximum performance with values near to those experimentally found. The catalyst was recovered from the final mixture by filtration and reused without regeneration showing a catalytic activity stable up to 4 or more reaction cycles. [ABSTRACT FROM AUTHOR]