Steam reforming of glycerol over Ni/Al2O3 catalyst

Glycerol steam reforming has been investigated in a 10-mm ID fixed-bed reactor containing Ni/Al2O3 catalyst using a wide range of the steam-to-carbon ratio (1.1 <= STCR <= 4.0) at temperatures between 723 K and 823 K. Physicochemical characterization revealed that the catalyst surface was populated by both weak and strong acid and basic sites although the catalyst appeared to have a net surface acidity. H-2, CO2 and CO were the main gaseous products with H-2:CO2 ratio at approximately 2.15 while H-2:CO ratio varied between 6.0 and 16.0 depending on the reactant feed composition. The specific glycerol consumption rate exhibited fractional reaction orders with respect to both glycerol (0.48) and steam (0.34) and activation energy of about 60 kJ mol(-1). Mechanistic considerations indicated that glycerol and steam underwent associative and dissociative adsorption, respectively on two different sites with the surface reaction being the rate-determining step. Additionally, carbon deposition has a positive dependency on the glycerol partial pressure, but it was inhibited in the presence of steam. (C) 2011 Elsevier B. V. All rights reserved.