In general, esterification reactions are favored by the increase in reaction temperature, excess of one of the reactants (usually alcohol), and additions of acid or basis catalysts. Esterification of oleic acid with m...In general, esterification reactions are favored by the increase in reaction temperature, excess of one of the reactants (usually alcohol), and additions of acid or basis catalysts. Esterification of oleic acid with methanol catalyzed by Nb2O5·nH2O calcined at different temperatures showed good conversion rates, especially at reaction temperature of 100°C and higher catalyst proportions. PLS calibration showed good results for predicting the amounts of methyl oleate in reaction products.展开更多
Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)...Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN) nanopowders. At first, Nb_2O_5reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassysubstance after cooling was dispersed and washed several times in distilled water to remove the Na^+ions. The as-prepared colloidal Nb_2O_5·nH_2O was subsequently mixed with acetic solution ofbarium acetate and magnesium acetate according to the required molar proportions and followed bygelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwaveQ-factor, of 10397 at 1,45GHz.展开更多
基金the Conselho Nacional de Desen-volvimento Científico e Tecnologico(CNPq),the Coor-denadoria de Aperfeicoamento de Pessoal do Nivel Superior(CAPES),the Fundacao de Amparoa Pesquisa do Espirito Santo(FAPES)and the Fundo de Apoio a Cien-cia e Tecnologia da Prefeitura de Vitoria(FACITEC)for financial support.
文摘In general, esterification reactions are favored by the increase in reaction temperature, excess of one of the reactants (usually alcohol), and additions of acid or basis catalysts. Esterification of oleic acid with methanol catalyzed by Nb2O5·nH2O calcined at different temperatures showed good conversion rates, especially at reaction temperature of 100°C and higher catalyst proportions. PLS calibration showed good results for predicting the amounts of methyl oleate in reaction products.
文摘Commercially available niobium (V) oxide [Nb_2O_5], with barium acetate[Ba(CH_3COO)_2] and magnesium acetate [Mg(CH_3COO)_2·4H_2O] was used as the starting material inthe sol-gel process for preparing Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN) nanopowders. At first, Nb_2O_5reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassysubstance after cooling was dispersed and washed several times in distilled water to remove the Na^+ions. The as-prepared colloidal Nb_2O_5·nH_2O was subsequently mixed with acetic solution ofbarium acetate and magnesium acetate according to the required molar proportions and followed bygelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwaveQ-factor, of 10397 at 1,45GHz.
