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Abstract: Polymeric catalytic membranes were prepared in two different ways for the transesterification of soybean oil. In a first approach 1,5,7-Triazabicyclo [4.4.0] dec-5-ane (TBD) was anchored to a PVA membrane using epichlorohydrin as linking agent. Another attempt was to synthetize poly(N-vinylguanidine) avoiding the need of anchoring the TBD in a polymeric matrix. Catalytic runs were performed in jacket batch reactors and even though the results are still preliminary, they appeared to be promising. The catalysts were characterized by thickness measurements, swelling degree and Fourier Transform Infrared Spectroscopy (FTIR). [Copyright &y& Elsevier]

Abstract: The esterification of palmitic acid with methanol was studied using tungstophosphoric acid (PW), molibdophosphoric acid (PMo) and tungstosilicic acid (SiW) immobilized by sol–gel technique on silica, at 60°C. It was observed that the catalytic activity decreases in the series: PW-silica>SiW-silica>PMo-silica. A series of PW immobilized on silica with different PW loadings from 2.5wt.% to 8.4wt.% were prepared. It was observed that the PW-silica2 (with 4.2wt.%) shows the highest catalytic activity on esterification of palmitic acid with methanol. Catalytic stability of the PW-silica2 was evaluated by performing consecutive batch runs with the same catalyst sample. After the second batch it was observed a stabilisation of the initial activity. In order to study the heteropolyacid lixiviation, a posterior catalytic experiment was carried out. The PW-silica2 was put in contact with methanol, without palmitic acid, during 72h. After this period, the catalyst was separated from methanol by centrifugation, and the palmitic acid was added to the reaction mixture. It was observed that the reaction only occurs in the heterogeneous phase. The PW-silica2 was also used as catalyst in esterification of others fatty acids: oleic and stearic acid. It was also observed a good catalytic activity of PW-silica2 for the different substrates used in the esterifications. [Copyright &y& Elsevier]

Abstract: PVA supported catalytic membranes have been synthesized by mutual γ-irradiation method using adipic acid (AA) and succinic acid (SA) as crosslinkers and a commercial ion exchange resin as catalyst. These membranes were tested as catalyst under batch conditions in esterification reaction of lauric acid to methyl laurate aiming biodiesel production. The effect of different synthesis parameters such as crosslinker, crosslinker's concentration and absorbed dose on membranes’ physical–chemical properties and catalytic activity was studied. Results demonstrated that PVA supported resin membranes are effective catalysts in the lauric acid esterification reaction. Also showed that PVA-SA membranes exhibit the better catalytic properties and, within the range of conditions studied, an increase in the γ-radiation dose leads to a slight increase of membranes’ catalytic activity. [Copyright &y& Elsevier]

Highlights: [•] Sulfonic acid catalysts supported on chitosan were prepared. [•] Esterification of fatty acids was carried out over chitosan with sulfonic groups. [•] High catalytic activity was observed. [ABSTRACT FROM AUTHOR]

Abstract: Tungstophosphoric acid (PW), molybdophosphoric acid (PMo) and tungstosilicic acid (SiW) immobilized on SBA-15 were used, as catalysts, in the esterification of palmitic acid with methanol, at 60°C. Catalysts were characterized by N2 adsorption, FTIR, X-ray diffraction, ICP-AES and TEM. All catalysts exhibited high catalytic activity in palmitic acid esterification with methanol. It was observed that the catalytic activity decreases in the follow series: PW1-SBA-15>SiW-SBA-15>PMo-SBA-15. A series of PW immobilized on SBA-15 with different PW loadings from 2.7wt% to 8.3wt% were prepared. It was observed high catalytic activity with low amount of tungstophosphoric acid immobilized on SBA-15. In order to optimize the reaction conditions, the effect of different parameters, such as catalyst loading, carbon length of the alcohol and temperature, molar ratio of fatty acid to methanol in the presence of PW3-SBA-15 were studied. PW3-SBA-15 catalyst can be separated from reaction system for re-use. It was observed a small leaching of the PW from SBA-15 to liquid phase. PW3-SBA-15 catalyst was also used in the esterification of stearic and oleic acid with methanol. High catalytic activity was observed. [ABSTRACT FROM AUTHOR]

Abstract: Biodiesel was produced by transesterification of soybean oil with methanol using poly(vinyl alcohol) membranes as solid base catalysts. The membranes were prepared dispersing hydrotalcite in the polymer solution. The reactions were carried out at 60°C in a three-necked batch reactor using all the catalysts in the form of pellets. The effect of the hydrophobic/hydrophilic properties of the membranes on the catalytic activity was studied. Membranes with a poly(vinyl alcohol) matrix totally or partially acetylated, in order to increase hydrophobicity, or treated with succinic anhydride, in order to increase hydrophilicity, were prepared. The best results were obtained with the most hydrophilic membrane. In order to evaluate the catalyst stability a same sample of that membrane was used in seven consecutive runs. These catalysts are more active in the transesterification of soybean oil with methanol than the free hydrotalcite and can be reused for several runs without any further reactivation. A diffusion-kinetic model was developed in an attempt to explain the induction period observed in the kinetic curves. [ABSTRACT FROM AUTHOR]

Abstract: The esterification of palmitic acid with methanol was studied using poly(vinyl alcohol) cross-linked with sulfosuccinic acid (SSA) and polystyrene cross-linked with divinylbenzene with sulfonic acid groups, as catalysts, at 60°C. It was observed that the PVA matrixes with sulfonic acid groups were more active than the polystyrene ones. With the most active polymeric matrix (PVA_SSA40), an almost 90% equilibrium conversion was achieved after 2h. Further, the optimisation of reaction parameters, such as, catalyst loading, molar ratio alcohol to fatty acid and type of alcohol was carried out with PVA_SSA40 catalyst. Catalytic stability of the PVA_SSA40 was evaluated by performing consecutive batch runs with the same catalyst sample. After the second batch, a stabilisation of the catalytic activity was observed. The PVA_SSA40 was also used as catalyst in the esterification of oleic and stearic acid with methanol, having been obtained an equilibrium conversion of almost 80%. In order to become the biodiesel totally biogenerated, the esterification of palmitic acid was carried out with ethanol, at 60°C and 80°C. It was observed that the reaction rate is slower when the reaction is carried out with methanol, at 60°C. In a posterior catalytic experiment at 60°C, PVA_SSA40 showed catalytic activity to obtain biodiesel from animal fats (lard), in the presence of methanol. [Copyright &y& Elsevier]

Abstract: The transesterification of soybean oil with methanol was studied using solid acid catalysts, at 60°C and atmospheric pressure. Nafion membranes, ion-exchange resins and poly(vinyl alcohol) membranes containing sulfonic groups were used as catalysts for the transesterification reaction studied. The reactions were carried out in a three-necked reactor using all the catalysts in the form of pellets. Nafion and PVA membranes in the form of film were also used in a membrane reactor. The PVA membrane modified with sulfossucinic acid was, in both cases, the most active catalyst. The concentration profiles obtained with the catalysts in the form of pellets exhibited an initial induction period, which disappears when the reaction is performed in the membrane reactor. [Copyright &y& Elsevier]