Influence of reaction parameters on the activity of ruthenium based catalysts for glycerol steam reforming

Mg(Al)O supported Ru catalysts with low loading of active metal (0.6 wt.%), obtained from simple inorganic salts, were tested, for the first time, in the steam reforming (SR) of glycerol to hydrogen rich mixtures. The catalysts, obtained by simple wet impregnation of Ru salts on a Mg(Al)O mixed oxide followed by high temperature oxidation/reduction treatments, were systematically characterized by numerous complementary techniques, both before and after their use in SR reaction. The changes of the performances (activity, selectivity and stability) of Ru/Mg(Al)O catalysts were studied, produced by varying reaction temperature (450-650 oC) at fixed glycerol concentration (10 wt.% in water), and by varying glycerol concentration (10-40 wt.% in water) at fixed reaction temperature (550 oC). The best performances (in terms of glycerol conversion, H2 yield and CO2 selectivity), at lowest reaction temperature, were obtained operating at 10 wt.% glycerol and 550 oC. Correspondingly, catalysts showed glycerol conversion, H2 yield and CO2 selectivity close to 100%. Methane was practically absent, CO selectivity was lower than 3.5% and coke deposition quite scarce (1.1 mgC gcat -1 h-1). However, at this temperature, catalysts exhibited stable, although lower, performances up to 40 wt.% glycerol concentrations. Significantly, catalytic performances could be improved increasing reaction temperature up to 650 oC keeping other advantages.