2 nd Mercosur Congress on Chemical Engineering 4 th Mercosur Congress on Process Systems Engineering 1 A STABLE, NOVEL CATALYST IMPROVES HYDROGEN PRODUCTION S. Irusta, J.Múnera, C. Carrara, E.A. Lombardo, L.M. Cornaglia * Instituto de Investigaciones en Catálisis y Petroquímica (FIQ, UNL-CONICET) Abstract. The membrane reactors employed for the dry reforming reaction were based on different membrane types. This reaction taken as a source of H 2 , was performed in the present work using a well- known catalyst, Rh/La 2 O 3 , together with a novel one, Rh/La 2 O 3 -SiO 2 , in a hydrogen-permeable membrane reactor. The catalysts were characterized by DRX, TPR, FTIR, LRS, H 2 and CO chemisorption. The effect of the operation variables upon the performance of the membrane reactor was also studied. The novel Rh(0.6%)/La 2 O 3 (27%)-SiO 2 catalyst proved to be the best formulation. Operating at 823 K, both methane and CO 2 conversions were 40% higher than the equilibrium values, producing 0.5 mol H 2 /mol CH 4 . This catalyst, tested at W/F three times lower than the Rh(0.6%)/La 2 O 3 , showed a similar performance. In all cases, the activity of the Rh catalysts remained constant after 100 hours on stream at 823 K. The presence of tiny amounts of graphite only detectable through LRS did not endanger membrane stability. The incorporation of the promoter (La 2 O 3 ) to the silica support induced a parallel increase in the metal dispersion (CO adsorption). The concentration of surface Rh atoms slightly increased with lanthanum addition. The better performance of Rh(0.6%)/La 2 O 3 (27%)-SiO 2 was related to the high dispersion and reaction rate of this formulation. Key words: Membrane reactor, hydrogen production, CO 2 reforming. 1. Introduction The dry reforming of methane as a source of H 2 was performed using a commercial Ni catalyst and supported Ru, Pd, Ir and Pt catalysts in hydrogen-permeable membrane reactors. The main problems encountered in this application were the abundant formation of coke, deleterious to the membrane (Cornaglia et al, 2004), and catalyst deactivation. Appropriate catalysts preventing the formation of carbon deposits are needed to avoid membrane damage. The membrane reactors employed for the above mentioned reaction were based on different membrane types such us porous membranes catalytic porous membranes, silica modified vycor and thin palladium film (Ferreira-Aparicio et al, 2002; Liu and Au, 2001). In previous studies (Cornaglia et al, 2004), we reported that the CH 4 conversion can be greatly improved by removing the hydrogen formed with a stable and highly selective Pd-Ag dense membrane. The rhodium catalysts supported on lanthanum were active and stable for the dry reforming reaction, despite the low dispersion of the metal. Vidal et al. (2001) reported dispersion values as high as 100 % in Rh catalysts when a composite La 2 O 3 -SiO 2 solid was used as support. A higher metal dispersion could lead to a higher activity in the dry reforming; a better performance of the membrane reactor would consequently be obtained. Infrared spectra of adsorbed carbon monoxide can give valuable information about surface sites in mixed metal catalysts (Beutel et al, 1997). Experimental information is available for CO adsorption on Rh particles supported on various metal oxide supports. Knözinger and co-workers (1997) used FTIR spectroscopy of * To whom all correspondence should be addressed. Address: Santiago del Estero 2829 FIQ, UNL. 3000 Santa Fe, Argentina E-mail: lmcornaglia@fiqus.unl.edu.ar