The predicted shortage of fossil fuels and related environmental concerns have recently attracted significant attention to scientific and technological issues concerning the conversion of biomass into fuels. First-generation biodiesel, obtained from vegetable oils and animal fats by transesterification, relies on commercial technology and rich scientific background, though continuous progress in this field offers opportunities for improvement. This review focuses on new catalytic systems for the transesterification of oils to the corresponding ethyl/methyl esters of fatty acids. It also addresses some innovative/emerging technologies for the production of biodiesel, such as the catalytic hydrocracking of vegetable oils to hydrocarbons. The special role of the catalyst as a key to efficient technology is outlined, together with the other important factors that affect the yield and quality of the product, including feedstock-related properties and various system conditions.

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A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-l-ol (ohyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol, el method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9~Y~adecen-l-ol and total alcohol (9~ctadecen-l~l + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%. KEY WORDS: 9-Octadecen-l-al, oleie acid, ruthenium-tin-alumina catalyst, selective hydrogenation, sol-gel method.

Interesterified blends of hard palm stearin (IV of 11) and canola oil (hPS/CO) in ratios of 20 : 80, 30 : 70, 40 : 60, 50 : 50, 60 : 40 and 70 : 30 were prepared using immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM). Comparison of physical properties was carried out between non-interesterified and enzymatically interesterified products by monitoring their slip melting point (SMP), solid fat content (SFC), melting thermogram and polymorphism behavior. The Lipozyme TL IM-catalyzed interesterification significantly modified the physical properties of the hPS:CO blends. The results showed that all the interesterified blends had lower SMP and SFC than their unreacted blends. The SMP result showed that the interesterified blends of hPS/CO 40 : 60, 50 : 50 and 60 : 40 could be useful for stick margarine and shortening applications, respectively. From the SFC analysis, the interesterified blends of hPS/CO 40 : 60 have SFC curves similar to vanaspati. The interesterified blends of hPS/CO 50 : 50 and 60 : 40 have SFC curves similar to margarines, puff pastry margarine and shortening. Interesterification had replaced the higher-and lower-melting triacylglycerols by the middle-melting triacylglycerols, yielding mixtures of lower SMP and SFC, compared to the original palm stearin. X-ray diffraction analysis indicated the appearance of b' crystals in all the interesterified hPS/CO blends from predominantly b-type oils.

Refined, bleached and deodorized palm olein (RBD POo) with an iodine value (IV) of 62 was chemically interesterified with methyl oleate (MO) at a ratio of 50:50 (w/w). The reaction was carried out at 110°C in the presence of sodium methoxide as a catalyst using a 100-kg pilot scale reactor. Randomization between 15 and 30 min resulted in less free fatty acid (FFA) formation and higher oleic content in the interesterified product as compared to longer reaction time of 60-90 min. Sodium methoxidecatalyzed ester interchange increased the oleic content of the interesterified product to more than 57% from its initial content of 45%. The product obtained also has an IV of more than 75. The interesterified oil was then subjected to dry fractionation in a 200-kg De Smet jacketed crystallizer at 8°C to further enhance the oleic content of the liquid olein fraction. The resulted olein had an improved cloud point and higher IV of 81. The solid stearin had a slightly higher IV and oleic content as compared to normal palm stearin. The solid fat content was comparable to normal palm oil. The pilot scale study has proven a successful conversion of laboratory findings to a larger scale production and gave the most realistic information for possible commercialization.