DISEÑO Y SINTESIS DE Ga2O3 CON PARÁMETROS ESTRUCTURALES

C. BARRIOS, S. COLLINS, K. SAPAG, A. BONIVARDI

La Plata

Congreso; XIV Cong Argentino de Catálisis y 4to Cong de Cat del Mercosur; 2007

Sociedad Aregntina de Catálisis

A rational design for the synthesis of mesostructured Ga2O3 was used. Ga(NO3)3 (inorganic precursor), urea or ammonia solution (precipitant agent), 1-propanol (polarity modifier and homogenizer), and lauric acid (template) were employed. The specific area and the pore size distribution of the oxides were determined by the BET’s and BJH’s method, respectively. All the synthesized materials were mesostructured. In the template absence, the materials have SBET < 85 m2 g-1, pore volumen (Vp) < 0.07 cm3 STP g-1 and pore average diameter (dp BJH) < 40 Å, regardless the precipitant agent used and/or the presence of 1-propanol. However, the use of lauric acid together with ammonia solution made possible the improvement of the structural parameters of the resulting oxide (APL): SBET = 106 m2 g-1, Vp = 0.22 cm3 STP g-1 and dp BJH = 51 Å. It is suggested that the autohydrolysis process of Ga(III) controls the precipitation when using urea, and thus the occlusion of the template into the material structure is avoided. The study of H2 adsorption by infrared spectroscopy (IR) was used to analyze the coordination of surface Ga(III) cations. The sequential adsorption of CH3OH and CO2, followed by IR, revealed the formation of monomethyl carbonate at 323 K, a key intermediate in direct production of dimethyl carbonate.