Anju Chadha

Biodiesel was prepared from the non-edible oil of Pongamia pinnata by transesterification of the crude oil with methanol in the presence of KOH as catalyst. A maximum conversion of 92% (oil to ester) was achieved using a 1:10 molar ratio of oil to methanol at 60°C. Tetrahydrofuran (THF), when used as a co-solvent increased the conversion to 95%. Solid acid catalysts viz. Hβ-Zeolite, Montmorillonite K-10 and ZnO were also used for this transesterification. Important fuel properties of methyl esters of Pongamia oil (Biodiesel) compare well (Viscosity = 4.8 Cst @ 40°C and Flash point = 150°C) with ASTM and German biodiesel standards. © 2005 Elsevier Ltd. All rights reserved.

Lipase from Pseudomonas cepacia was used to prepare esters of hydrocinnamic acid by direct esterification of the carboxylic acid in good yields (70-83%). For some esters, transesterification gave better yields (92%). Optimization of the reaction conditions resulted in a dramatic increase in the yield of the product ester. The role of solvents was studied. Notably, cinnamic acid esters are not formed under these conditions. © 2002 Elsevier Science Inc. All rights reserved.

The kinetics of transesterification of Pongamia oil using methanol at 60°C were studied. The forward as well as the reverse rate constants of all three steps involved in the transesterification of Pongamia oil are reported for the first time. Among the forward rate constants, the one governing the conversion of TG to DG was the highest and the one for DG to MG was the lowest. A distinct feature of the present work is the direct estimation of the equilibrium constants of all three steps by measuring the concentrations of TG, DG, and MG at very long reaction times. This reduced the number of parameters to be determined from the kinetic data by one-half, thereby leading to more accurate estimation of the rate constants. The equilibrium constant of the final step involving the conversion of MG to methyl ester and glycerol was at least an order of magnitude greater than that of the first two reaction steps. A detailed comparison was made with kinetic parameters reported in literature. The trend in the relative magnitudes of the rate constants appears to be unique to Pongamia oil. Copyright © 2006 by AOCS Press.

Lipase Pseudomonas cepacia (PS) catalyzed transesterification of ethyl 3-phenylpropanoate with eleven alcohols was investigated in three ionic liquids [ILs], [Bmim]BF4, [Bmim]PF6, and [Bmim]Tf2N, consisting of an identical cation and different anions. The yields were higher in hydrophobic ILs [Bmim]Tf2N (55-96%) and [Bmim]PF6 (22-95%), than in hydrophilic [Bmim]BF4 (0-19%). The incubation of lipase PS in hydrophobic ILs for a period of 20-300 days at room temperature resulted in an increased yield of 62-98% in [Bmim]Tf2N and 45-98% in [Bmim]PF6, respectively. The lipase PS-hydrophobic IL mixture was recycled five times without any decrease in the yield of the products. In another set of experiments, the hydrolytic activity of the enzyme was determined after incubation in each of the three ILs and in hexane for 20 days at room temperature. It was found to be 1.8- and 1.6-fold higher in [Bmim]Tf2N and [Bmim]PF6, respectively, remained unchanged in [Bmim]BF4 and was 1.6 times lower in hexane as compared to the non-incubated enzyme. © 2008 Elsevier B.V. All rights reserved.

The kinetics of the transesterification of vegetable oil is known to follow a three-step reaction mechanism. The third step involves the transesterification of MG. In this study, the transesterification of MG obtained from crude Pongamia oil was achieved with methanol in the presence of KOH as the catalyst. A MG/methanol ratio of 1:10 was used at different temperatures (30, 45, 55, and 60°C). 1H NMR was used to monitor the progress of transesterification. The study revealed that the kinetics of this reaction followed a reversible second-order model, with a good fit obtained for all temperatures except 30°C. This result is explained as arising out of the importance of transport effects at low temperatures. The forward rate constant increased with an increase in temperature, whereas the reverse rate constant showed a decreasing trend, suggesting that the proposed reverse reaction was not an elementary step.