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.

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High-oleic palm oil (HOPO) with an oleic acid content of 59.0% and an iodine value (IV) of 78.2 was crystallized in a 200-kg De Smet crystallizer with a predetermined cooling program and appropriate agitation. The slurry was then fractionated by means of dry fractionation at 4, 8, 10, 12, and 15 degrees C. The oil and the fractionated products were subjected to physical and chemical analyses, including fatty acid composition, triacylglycerol and diacylglycerol composition, solid fat content, cloud point, slip melting point, and cold stability test. Fractionation at 15 degrees C resulted in the highest olein yield but with minimal oleic acid content. Due to the enhanced unsaturation of the oil, fractionation at relatively lower crystallization temperature showed a considerable effect on fatty acid composition as well as triacylglycerol and diacylglycerol composition of liquid fractions compared to higher crystallization temperature. The olein and stearin fractionated at 4 degrees C had the best cold stability at 0 degrees C and sharper melting profile, respectively.

The adsorption behaviour and the micro-and mesopore size distributions of commercial palm kernel shell activated carbons (PKSAC) and other commercial activated carbon are characterized. The results showed that PKSAC are predominantly microporous materials, where micropores account 68-79% of total porosity. On the other hand, commercial activated carbons: Norit SX Plus, Calgon 12 × 40, and Shirasagi "A" activated carbons contained high mesopore fraction ranging from 33 to 52%. The analysis showed that the degree of mesoporosity of PKSAC is increased steadily with the decrease of particle size. This is due to the presence of channels interconnect the smaller pores in the interior of smaller particle size PKSAC. The smaller size PKSAC particle that is highly mesoporous has preformed better on the adsorption of larger molecules such as methylene blue. On the other hand, bigger size PKSAC particle has better performance on the adsorption of smaller adsorbates such as iodine. Nomenclature q tAmount of methylene blue ions adsorbed at time t (mg/g) Q 0Number of moles of solute adsorbed per unit weight of activated carbon (mol/g) A MCross sectional area of one MB ion (m 2 ) bEnergy of adsorption constant of Langmuir model C e Solute concentration in the aqueous phase at time t (mg/L) C 0 Initial solute concentration in the aqueous phase (mg/L) D meso Average mesopore diameter determined by BJH model (Å) D micro Mean micropore diameter determined by HK model (Å) K F Freundlich isotherm equation constant [mg/g(1/mg) 1/n ] k f Rate constant of pseudo-first-order equation defined in (4) (min −1 ) k i Rate parameter of intraparticle diffusion defined in (6) (mg L −1 min −1 ) k s Rate constant of pseudo-second order equation defined in (5) (L mg −1 .min −1 ) N a Avogrado's number (6.023 × 10 23 ) 1/n Freundlich isotherm equation constant (dimensionless) q e Amount of methylene blue ions adsorbed at equilibrium (mg/g) R 2Regression factor of sorption kinetic plots S BET BET specific surface of activated carbon (m 2 /g) S MB Surface coverage of methylene blue ions within activated carbon (m 2 /g) S micro Surface area of activated carbon due to micropores (m 2 /g) t Time (min) 508 Adsorption (2009) 15: 507-519V meso Mesopore volume obtained by BJH model (cm 3 /g) V micro Micropore volume obtained by DR model (cm 3 /g) V t Total pore volume of activated carbon (cm 3 /g) X MB Fraction of surface coverage of methylene blue ions over BET surface area (S MB /S BET )