Optimization of cotton seed biodiesel quality (critical properties) through modification of its FAME composition by highly selective homogeneous hydrogenation

The catalytic (homogeneous) hydrogenation of biodiesel's polyunsaturated fatty acid methyl esters (FAME), synthesized by transesterification of vegetable (cotton seed) oil, selectively to monounsaturated FAME, could upgrade the final quality of biodiesel. The final fuel can be optimized to have a higher cetane number and improved oxidative stability. The low-temperature performance after hydrogenation (CFPP) might be worst, but this, could be further improved through selective wintering and/or blending. The homogeneous hydrogenation of FAMEs of cotton seed biodiesel was catalyzed by the catalyst precursor RhCl3 center dot 3H(2)O and STPP-TiOA. Four groups of hydrogenation experiments were carried out regarding the effects of pressure, temperature, reaction time and molecular ratio C=C/Rh. Partial hydrogenation of cotton seed FAMEs took place under mild conditions of pressure and temperature and high catalytic activities were observed in very short reaction times, and for high molecular ratios C=C/Rh. Biodiesel's quality optimization studies, based on existing empirical models of biodiesel properties, were carried out in order to identify optimum FAME compositions and those hydrogenation conditions that could possibly supply them. (C) 2009 Elsevier Ltd. All rights reserved.