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Abstract: After production and formulation, but before being brought to market, gasoline must conform to the specifications set by regulatory agencies. Octane numbers are among the most important physico-chemical parameters to be evaluated because they are directly related to the performance and power of the engine. This study will evaluate the influence of the gasoline’s components on its octane numbers. To identify and quantify the major organic compounds in the gasoline sold within the metropolitan area of Salvador, Bahia, Brazil, gas chromatography was used. Toluene, m-xylene, n-hexane, n-heptane and 2-methyl-2-butene were selected for this study. Several gasoline samples with different ratios of the selected compounds were formulated, and their octane numbers were measured in a CFR engine. Based on the results, the system was optimized using the Doehlert matrix as a mathematical tool, which allowed the effects of the different hydrocarbons on the octane numbers to be visualized. From the experimental results, important information has been gathered for use by the producers and formulators of gasoline to facilitate the production of a higher quality fuel with a lower environmental impact. [Copyright &y& Elsevier]

Abstract: The transesterification of triglycerides by means of alkaline catalysts is the most widely used route for biodiesel production and reaction optimisation by multivariate methods has been used for biodiesel production from different vegetable oils. However, the application of simultaneous optimisation for biodiesel production from beef tallow has received little attention. In an effort to optimize the beef tallow biodiesel production, a combination of the full factorial design and the Doehlert matrix was applied, and the effects of temperature, reaction time, catalyst concentration and alcohol:tallow molar ratio and their reciprocal interactions were assessed. The response variables under study were purity and yield of the final biodiesel product. In the selected condition [alcohol:tallow molar ratio(M)=7.5:1, catalyst:tallow mass ratio(C)=1.5%, reaction time(t)=20min and temperature=50°C], the conversion yield of tallow biodiesel was 88.4% and the purity was 99.4%. The final biodiesel obtained was analysed and showed to have good quality characteristics. [ABSTRACT FROM AUTHOR]