Síntesis de CH3OH a partir de CO2/H2 Empleando Ga-Pd/SiO2 como Catalizador: Influencia de los Productos de Reacción

D.L. CHIAVASSA; J.E. BARRANDEGUY; A.L. BONIVARDI; M.A. BALTANÁS

Gramado (Brasil)

Simposio; XX Simposio Iberoamericano de Catálisis; 2006

The synthesis of CH3OH from CO2/H2 mixtures using Ga-Pd/SiO2 promoted catalysts is strongly affected by the reaction products. At finite conversion, important amounts of water and carbon monoxide are also found in the system. Hence, a comprehensive evaluation of their impact on the process is particularly relevant. An experimental program was conducted, using a Berty-type CSTR recycle reactor, for a wide range of temperature (508-538 K), presssure (1-4 MPa), composition (H2/CO2 = 1, 3 and 6) and space velocities, including H2-CO-CO2 ternary mixtures as well. The deleterious effect of CO is attributed to its strong chemisorptive bonding onto the metal, which hampers the generation and transfer of dissociated hydrogen (Hs) from the Pd crystallites to the gallia; this effect alters both the activity and the selectivity of the catalyst. The detrimental impact of H2O (which is produced in every stoichiometric reaction of the system) is related with its interference on the availability of coordinatively unsaturated sites (cus) on the Ga2O3.3OH from CO2/H2 mixtures using Ga-Pd/SiO2 promoted catalysts is strongly affected by the reaction products. At finite conversion, important amounts of water and carbon monoxide are also found in the system. Hence, a comprehensive evaluation of their impact on the process is particularly relevant. An experimental program was conducted, using a Berty-type CSTR recycle reactor, for a wide range of temperature (508-538 K), presssure (1-4 MPa), composition (H2/CO2 = 1, 3 and 6) and space velocities, including H2-CO-CO2 ternary mixtures as well. The deleterious effect of CO is attributed to its strong chemisorptive bonding onto the metal, which hampers the generation and transfer of dissociated hydrogen (Hs) from the Pd crystallites to the gallia; this effect alters both the activity and the selectivity of the catalyst. The detrimental impact of H2O (which is produced in every stoichiometric reaction of the system) is related with its interference on the availability of coordinatively unsaturated sites (cus) on the Ga2O3.