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Abstract: In this study, poly(vinyl alcohol) (PVA) membranes crosslinked with sulfosuccinic acid (SSA) were used for the esterification of acetic acid by isoamylic alcohol. In order to study the effects of the crosslinking degree and, simultaneously, the amount of sulfonic groups, different membranes were prepared with SSA:PVA ratios in the range of 5–40mol%. Aiming at to eliminate the dependence between the amount of acid sites and the crosslinking degree, were also prepared PVA membranes in which the –SO3H groups were introduced by anchoring 5-sulfosalisilic acid (SA) on the PVA chains. The conversion of isoamylic alcohol increases when the amount of sulfosuccinic acid used in the polymer crosslinking is increased from 5 to 20%. However, when crosslinking degree increases from 20 to 40%, the conversion of isoamylic alcohol increases only slightly, probably due to the increase of molecules mobility restrictions, in the PVA matrix. In the case of the PVA membranes where the –SO3H groups were introduced by esterifying 5-sulfosalisilic acid on the PVA –OH groups, it was observed that membrane activity increases with the polymer crosslinking. It was also observed an increase of the activity of these membranes with the amount of –SO3H groups in the polymeric matrix. Catalytic stability of PVA membranes, prepared with SSA and SA, was evaluated by performing consecutive batch runs with the same membrane being observed, after the third run, a trend to stabilization of catalytic activity. An experiment with a membrane reactor operating under sweep gas pervaporation conditions is described. [Copyright &y& Elsevier]

The α-pinene hydration to α-terpineol was studied using as catalysts polymeric catalytic membranes consisting of HPMo entrapped in polyvinyl alcohol (PVA) cross-linked with 10, 20 and 30% of succinic acid, and HPMo encaged in USY zeolites dispersed in a polydimethylsiloxane (PDMS) matrix.In the case of HPMo/PVA membranes it was observed that membrane activity increases with the polymer cross-linking, due to the increase in membrane hydrophobicity, up to the limit of the increasingly restrictions to the molecules mobility. The HPMo-USY/PDMS membrane shows a significantly higher activity for pinene hydration, which is even higher than that observed with USY encaged HPMo alone. However, selectivity to α-terpineol (65% at 80% conversion) is slightly lower than that obtained for the HPMo/PVA cross-linked with 20 or 30% of succinic acid (70–75% at 90% conversion).For both catalytic membranes, HPMo/PVA or HPMo-USY/PDMS, the stability is reasonable good and catalyst activity increases in the subsequent uses of the same membrane, probably due to the interaction between retained α-terpineol and the polymer matrix. [Copyright &y& Elsevier]

Abstract: The hydrolysis of sucrose into glucose and fructose was carried out over composite catalysts at 80°C. These catalysts consisted of USY and Beta zeolites dispersed in polymeric matrices (PDMS and PVA). The swelling degree of polymers increased with the amount of zeolite immobilised in PDMS and PVA. This result can be explained by the increase in the polymeric matrix channelling. Additionally, the effective diffusivity of sucrose increases with the amount of USY and Beta zeolite that was dispersed in PDMS. The catalytic activity increases with the amount of zeolite dispersed in the polymeric matrix. The PVA composites showed higher catalytic activity than the PDMS ones. To study the catalytic stability of the Beta2/PVA catalyst, four consecutive batch runs were carried out with the same catalyst. The Beta2/PVA catalyst was recycled and reused with a negligible loss in its activity. [Copyright &y& Elsevier]

Abstract: The hydrolysis of sucrose was carried out over poly(vinyl alcohol) (PVA) with sulfonic acid groups, at 80°C. The products of sucrose hydrolysis were glucose and fructose. A series of PVA with different crosslinking degree were prepared. It was observed that the catalytic activity of PVA matrix increases with the crosslinking degree, due to the increases of the amount of sulfonic acid groups on PVA. Further, the influence of various reaction parameters, such as, catalyst loading, initial concentration of sucrose and temperature, on the hydrolysis of sucrose over PVA_40 was studied. It was found that at 80°C, with 0.511g of catalyst loading and with an initial concentration of sucrose of 0.6M, a sucrose conversion of about 90%, after 3h, could be obtained. The PVA_40 catalyst was recycled and reused with negligible loss in the activity. A simple kinetic model was developed assuming that the sucrose hydrolysis is an irreversible reaction and the first order with respect to the sucrose concentration. Since the concentration profiles of the reactant and the products do not exhibit any pronounced initial inductive period, the external and internal diffusion of the reactant and products on the catalyst were not considered. It was observed that the kinetic model fits experimental concentration data quite well. [Copyright &y& Elsevier]

Abstract: The methoxylation of α-pinene was studied using poly(vinyl alcohol) (PVA) containing sulfonic acid groups as catalysts. These groups were introduced by the direct reaction between –OH groups of PVA and sulfosuccinic acid (SSA). Poly(vinyl alcohol) catalysts were prepared using sulfosuccinic acid by varying the amount of SSA (5–40mol%). It was observed that the amount of acid sites increases with amount of SSA. It was also observed that the diffusivity of α-pinene through the polymeric catalysts decreases with the increase of crosslinking degree. The conversion of α-pinene increases when the amount of sulfosuccinic acid used in the polymer crosslinking is increased from 5% to 40%. However, when the crosslinking degree increases from 20% to 40%, the conversion of α-pinene increases only slightly. Good values of selectivity to α-terpinyl methyl ether (about 60% near complete conversion) were obtained over poly(vinyl alcohol) with sulfonic acid groups. Catalytic stability of the PVA_SSA20 was evaluated by performing consecutive batch runs with the same catalyst sample. After the third batch it was observed a stabilisation of the initial activity. A kinetic model was developed assuming that the α-pinene is consumed according to the parallel reaction network. Since the concentration profiles of the reagent and the products do not exhibit any pronounced initial inductive period, the external and internal diffusion of the reagents and products on the catalyst were not considered. It was observed that the kinetic model fits experimental concentration data quite well. [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]

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]