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Acetalization of glycerol with hexanal was studied over sulfonic acid-functionalized mesoporous silica (SBA-15), at 70 ºC. The product obtained were (2-pentyl-1,3-dioxolan-4-yl)methanol and 2-pentyl-1,3-dioxan-5-ol. Materials with different amounts of sulfonic acid groups were prepared. The support functionalization was achieved by the introduction of 3-(mercaptopropyl)trimethoxysilane onto the surface of these materials by grafting technique. The [SO 3 H]-SBA-15 catalysts were characterized by nitrogen adsorption at 77 K, X-ray diffraction, SEM and titrations. All the catalysts were active in the studied reaction being the [SO 3 H] 3 -SBA-15 the best one. It was observed that the reaction rate increase with the amount of sulfonic acid groups on SBA-15 until a maximum. With high amounts of sulfonic groups, a decrease of activity is observed. Good values of selectivity to (2-pentyl-1,3-dioxolan-4-yl)methanol were obtained with mesoporous silicas anchored sulfonic acid groups. Catalytic stability of the [SO 3 H] 3 -SBA-15 was evaluated by performing consecutive batch runs with the same catalyst sample. The material showed a good catalytic stabilization. [Display omitted] • Acetalization of glycerol with hexanal was carried out over SBA-15 with sulfonic groups. • High catalytic activity of [SO 3 H] 3 -SBA-15. • Good selectivity to (2-pentyl-1,3-dioxolan-4-yl) methanol product. • Good catalytic activity after the fifth use. [ABSTRACT FROM AUTHOR]

Acetalization of glycerol with hexanal was studied over sulfonic acid-functionalized mesoporous silica (SBA-15), at 70 ºC. The product obtained were (2-pentyl-1,3-dioxolan-4-yl)methanol and 2-pentyl-1,3-dioxan-5-ol. Materials with different amounts of sulfonic acid groups were prepared. The support functionalization was achieved by the introduction of 3-(mercaptopropyl)trimethoxysilane onto the surface of these materials by grafting technique. The [SO 3 H]-SBA-15 catalysts were characterized by nitrogen adsorption at 77 K, X-ray diffraction, SEM and titrations. All the catalysts were active in the studied reaction being the [SO 3 H] 3 -SBA-15 the best one. It was observed that the reaction rate increase with the amount of sulfonic acid groups on SBA-15 until a maximum. With high amounts of sulfonic groups, a decrease of activity is observed. Good values of selectivity to (2-pentyl-1,3-dioxolan-4-yl)methanol were obtained with mesoporous silicas anchored sulfonic acid groups. Catalytic stability of the [SO 3 H] 3 -SBA-15 was evaluated by performing consecutive batch runs with the same catalyst sample. The material showed a good catalytic stabilization. [Display omitted] • Acetalization of glycerol with hexanal was carried out over SBA-15 with sulfonic groups. • High catalytic activity of [SO 3 H] 3 -SBA-15. • Good selectivity to (2-pentyl-1,3-dioxolan-4-yl) methanol product. • Good catalytic activity after the fifth use. [ABSTRACT FROM AUTHOR]

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]

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: The acetoxylation of α-pinene was carried out over SBA-15 with sulfonic acid groups. The products of acetoxylation of α-pinene are acetates (α-terpinyl acetate, bornyl acetate and β-fenchyl acetate) and hydrocarbons (camphene, tricyclene, limonene, γ-terpinene, terpinolene and α-terpinene). Catalysts with different amount of sulfonic acid groups were prepared. It was observed that the activity increases with increase of the surface area and porous volume. Catalytic stability of the sample that showed the highest activity (C1) was evaluated by performing consecutive batch runs with the same catalyst sample. After the fifth batch, the catalyst exhibited a good initial 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]

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]