Bio-hydrogen production by APR of C 2 -C 6 polyols on Pt/Al 2 O 3 : Dependence of H 2 productivity on metal content

Abstract

The effect of the platinum loading on the production of hydrogen by aqueous-phase reforming of ethylene glycol, glycerol, xylitol and sorbitol was studied on Pt/Al2O3 catalysts containing 0.30, 0.57, 1.50 and 2.77 Pt%. Catalytic runs were performed at a space velocity of 1.2h-1, 498K, 29.3bar and using a polyol(1.0%)/water feed. The total polyol conversion and the polyol conversion to gaseous products increased with surface Pt concentration (Pts, μmol Pt/gcat). Similarly, the yield and the productivity to hydrogen (Pr, molH2/gh) increased continuously with Pts in all the cases, but the Pr values diminished with the polyol chain length. Coke formation depended on Pts and the polyol size; the amount of carbon formed on the catalyst increased indeed with Pts and diminished with the polyol chain length. The metal fraction was severely sintered during the APR reaction, irrespective of the reactant size. Nevertheless, the magnitude of the Pt dispersion drop was not dependent on the amount of platinum on Pt/Al2O3 catalysts.