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Esterification of free fatty acids over chitosan with sulfonic acid groups
Caetano, CS; Caiado, M; Ramos, A; Fonseca, I; Vital, J; Castanheiro, JChitosan, which is an abundant biopolymer, with sulfonic acid groups was used as an efficient, environmentally friendly heterogeneous catalyst for the esterification of free fatty acids with methanol into their more fatty acid methyl ester. Sulfonic acid catalysts supported on chitosan have been studied in the esterification of palmitic acid with methanol at 60 C. The sulfonic acid groups were introduced onto ...
Mesoporous carbon as an efficient catalyst for alcoholysis and aminolysis of ep...
Matos, I; Neves, P; Castanheiro, J; Perez-Mayoral, E; Martin-Aranda, R; Duran-Valle, C; Vital, J; Botelho do Rego, A; Fonseca, IThe ring opening reaction of epoxides by alcohols and amines using mesoporous activated carbon as efficient and environmentally friendly heterogeneous catalyst is reported. Carbon xerogels were synthesized by polymerization of resorcinol and formaldehyde. The surface of the activated carbon was oxidized in liquid phase with HNO3 and then functionalized with H2SO4. Chemical and textural characterization by eleme...
Hydrolysis of sucrose over composite catalysts
Pito, D; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JThe 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 diff...
SBA-15 with sulfonic acid groups as a Green Catalyst for the acetoxylation of α...
Machado, J; Castanheiro, J; Matos, I; Ramos, A; Vital, J; Fonseca, IThe acetoxylation of a-pinene was carried out over SBA-15 with sulfonic acid groups. The products of acetoxylation of a-pinene are acetates (a-terpinyl acetate, bornyl acetate and b-fenchyl acetate) and hydrocarbons (camphene, tricyclene, limonene, g-terpinene, terpinolene and a-terpinene). Catalysts with different amount of sulfonic acid groups were prepared. It was observed that the activity increases with in...
Acetylation of glycerol over heteropolyacids supported on activated carbon
Ferreira, P; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JThe acetylation of glycerol was carried out over dodecatungstophosphoric acid (PW) supported on activated carbon, being the monoacetin, diacetin and triacetin the reaction products. A series of catalysts, with different heteropolyacid loading (from 3.5 to 6.5 wt.%), were prepared. It was observed that the catalytic activity increases with the amount of PW immobilized on the activated carbon, being the PW2_AC (w...
Valorization of glycerol into fuel additives over zeolites as catalysts
Serafim, H.; Fonseca, I.; Ramos, A.; Vital, J.; Castanheiro, J.Acetalisation of glycerol with butanal has been investigated over a range of zeolites with different pore structures and acidity (USY with different Si/Al ratio, BEA and ZSM-5). The products of glycerol acetalisation were (Z + E)-(2-propyl-1,3-dioxolan-4-yl) methanol (five-member ring acetal) and (Z + E)- 2-propyl-1,3-dioxan-5-ol (six-member ring acetal). The results showed an optimum in activity for Si/Al rati...
Esterification of free fatty acids to biodiesel over heteropolyacids immobilize...
Tropecêlo, A; Casimiro, M; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JoseTungstophosphoric 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 cataly...
Methoxylation of alpha-pinene over heteropolyacids immobilized in silica
Pito, DS; Matos, I; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JoséThe methoxylation of a-pinene was studied using heteropolyacids immobilized on silica as catalysts, at 60 ºC, being the a-terpinyl methyl ether the main product. Tungstophosphoric acid (PW), molybdophosphoric acid (PMo), tungstosilicic acid (SiW) and molybdosilicic acid (SiMo) were immobilized on silica by sol–gel method. It was observed that the catalytic activity of the silica-supported heteropolyacids decrea...
Valorisation of glycerol by condensation with acetone over silica-included hete...
Ferreira, P; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JThe acetalisation of glycerolwasstudied using heteropolyacids, immobilized in silica, as catalysts, at 70 ◦C. The main product of glycerol acetalisation was solketal. The tungstophosphoric (PW), molybdophosphoric (PMo), tungstosilisic (SiW) and molybdosilisic (SiMo) acids were immobilized in silica by sol–gel method. It was observed that the catalytic activity decreases in the series: PW-S > SiW-S >PMo-S > SiMo...
Esterification of fatty acids to biodiesel over polymers with sulfonic acid groups
Caetano, CS; Guerreiro, L; Fonseca, I; Ramos, A; Vital, J; Castanheiro, JEThe 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 ºC. It was observed that the PVAmatrixes with sulfonic acid groups were more active than the polystyrene ones. With the most active polymeric matrix (PVA_SSA40), an almost 90% equilibrium...
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