Effect of ZrO2 addition on Ni/Al2O3 catalyst to produce H2 from glycerol

In this work, ZrO2 was employed as support and as Al2O3 modifier of Ni based catalysts due to its special interesting characteristics. The catalytic activity of these systems was studied in steam reforming of glycerol to produce H2. As the activity results at 773 K and 873 K showed, the NiZ catalyst allowed low glycerol conversion and H2 production when compared to the NiγA catalyst. Moreover, the NiZ catalyst was not able to reform intermediate liquid products into gaseous products.The behaviour of the NiγA catalyst was improved when an intermediate content of ZrO2 was added to Al2O3, resulting in higher H2′ yield and capacity to reform intermediate products even at 773 K. This improvement seems to be related to a larger proportion of surface Ni° species (XPS). This Ni° proportion increase could be attributed to the formation of ZrO2–Al2O3 species. These species decreased Ni2+ species reduction temperature, favouring Ni2+ → Ni° transformation.

► Poor activity of NiZ catalyst was due to the low Ni content. ► ZrO2 support SBET was considered as responsible for low Ni content in NiZ catalyst. ► Among Al2O3-based catalysts, NiγA7.5Z catalyst showed the highest H2′ yield at 773 K. ► NiγA7.5Z catalyst had the optimum ZrO2 content to reduce Ni2+ and Al2O3 interaction. ► This catalyst showed better Ni2+ species reducibility and thus more Ni° proportion.