Novel Preparation and Magneto Chemical Characterization of Nano-Particle Mixed Alcohol Catalysts

Abstract

The preparation of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe nano-particle metal loaded mesoporous 1 mm spherical granular γ-Al 2 0 3 catalysts, by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, is accomplished. Parameters for calcination process were optimized using DTA. The properties of metal loaded γ-Al 2 O 3 granules were compared for the preparations starting with two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). Three sol-gel/oil-drop catalyst preparation methods; 1) Metal nitrate solutions co-entrapped-sol-gel 2) nano-particle metal oxide co-entrapped-sol-gel, and 3) Metal impregnation on preformed alumina granules, were used.Structure and composition of metal-loaded-granules were investigated using XRD, SEM, EDX, and surface area measurements (BET method). The nano-particle nature of catalysts was confirmed using SEM and X-ray diffraction. The reduction efficiency of hydrogenation of catalysts was examined by magnetic studies using a vibrating sample magnetometer (VSM). Catalysts could be effectively calcined at 450°C and the surface area values obtained were between 200-350 m 2 /g, indicating the mesoporous nature of catalyst support. Parameters affecting the metal loading process were also studied, and the optimum conditions were identified and reported for reproducible synthesis of the metal loaded γ-alumina granular particles.The catalyst activities of Fe, Co, and Co/Fe on alumina for the conversion of CO/H 2 and CO 2 /H 2 mixtures were investigated using Gas chromatography (GC) with N 2 as a standard carrier gas. Both, slurry-phase-batch and gas-phase-continuous-flow, reactors were used. Magnetization studies on reduced, CO/H 2 post-reaction catalyst in both gas and slurry phase were performed using vibrating sample magnetometer (VSM). Magnetic studies of post-reaction Co and Fe nano-catalysts showed that the formation of carbides is higher for iron compared to cobalt. In the Fe/Co mixed catalyst, it is observed that the presence of iron enhances the cobalt oxide reduction. Catalyst with mixed metal Fe/Co compositions at 12% nitrate solutions (prepared by sol-gel/oildrop) showed the best conversion rates for the syngas (CO+H 2 ). Nano-particle catalysts on solgel prepared mesoporous γ-alumina (particularly the nano-particle metal oxide co-entrapped-solgel) showed higher conversion rates compared to conventional catalysts prepared by coprecipitation methods.