Gloria Borda

Selective hydrogenation of furfural on Ir/TiO2 catalysts

Titania-supported Ir catalysts were used in the hydrogenation of furfural. Reactions were carried out in a stirred batch type reactor at 0.62MPa and 363K using a 0.10M solution of furfural in a 1:1 mixture n-heptane -ethanol as solvent. Catalysts containing 2 wt% of Ir were reduced in H2 flow at different temperatures in the range 473-773K. The catalysts were characterized by H2 chemisorption, TEM, TPR, TPD of NH3 and XPS. Conversion of furfural is higher at lower reduction temperatures, but leads to byproducts whereas reduction at higher temperatures shows selectivity to furfuryl alcohol close to 100%.

LIQUID-PHASE HYDROGENATION OF m-DINITROBENZENE OVER PLATINUM CATALYSTS

The m-dinitrobenzene hydrogenation to m-phenylenediamine in liquid phase was studied with platinum supported on SiO 2 , TiO 2 , Al 2 O 3 and Nb 2 O 5 catalysts. Incipient impregnation method was used to prepare the catalysts with 1wt% of Pt. The effect of the support and the reduction temperature (473 K or 773 K) were analyzed. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption (77 K), hydrogen chemisorption (298 K), transmission electron microscopy (TEM), temperature programmed reduction (H 2 -TPR) and temperature programmed desorption of ammonia (NH 3 -TPD). The results showed that Pt/ TiO 2 (HT) catalyst had a higher yield (60%) toward m- phenylenediamine and conversion level (98.2%) of m-dinitrobenzene. This behavior can be attributed to the reduction of PtO x crystallites to metallic Pt, small particle size and the strong metal-support interaction due to the migration of TiO x species on the Pt crystallites.

SYNTHESIS, CHARACTERIZATION AND CATALYTIC BEHAVIOR OF THE Ir/Nb(2)0(5)/Si0(2) SYSTEM IN THE CITRONELLAL HYDROGENATION

The citronellal hydrogenation was studied on Ir/Nb 2 O 5 -SiO 2 catalysts. A series of catalysts was synthesized with different niobia contents (Ir/N1 1.10%; Ir/N2 2.54%; Ir/N3 3.25%; Ir/N4 5.30%wt%) using the wet impregnation method. These catalysts were reduced in hydrogen atmosphere at low or high temperatures, 473K (LTR) or 773K respectively. Their structural and surface properties were investigated by XRD, TEM, XPS, DTP, FTIR, H 2 chemisorption at 298 K and surface specific area by using the BET method. The X ray diffraction studies revealed only the peaks due to niobia, mainly in those with higher niobia loading. No diffraction lines due to Ir were observed due to its lower content and/or to its high dispersion. The catalytic tests in the hydrogenation of citronellal were carried out in a batch reactor operated at 6.2 bar of H 2 and 343 K. All catalysts showed higher selectivity to isopulegol and to their products due to the cyclization of the citronellal molecule.

Hidrogenación de cinamaldehído sobre catalizadores Au/ZrO2 y Au/ZrO2-SiO2. Efecto del soporte y método de preparación

Se prepararon catalizadores de oro soportados en ZrO2 and ZrO2-SiO2 por impregnacion incipiente (Imp.I.) y depositacion-precipitacion con urea (DPU) con una carga nominal del metal del 1 %. Los solidos fueron caracterizados por difraccion de rayos X (DRX), fisisorcion de nitrogeno y reduccion a temperatura programada (TPR). La actividad catalitica fue evaluada en la hidrogenacion de cinamaldehido. La selectividad hacia el producto deseado es influenciada por la fase cristalina o amorfa del soporte y el metodo de deposicion del oro