The influence of SiO₂ doping on the Ni/ZrO₂ supported catalyst for hydrogen production through the glycerol steam reforming reaction

The glycerol steam reforming (GSR) reaction for H₂ production was studied comparing the performance of Ni supported on ZrO₂ and SiO₂-ZrO₂ catalysts. The surface and bulk properties were determined by ICP, BET, XRD, TPD, TPR, TPO, XPS, SEM and STEM-HAADF. It was suggested that the addition of SiO₂ stabilizes the ZrO₂ monoclinic structure, restricts the sintering of nickel particles and strengthens the interaction between Ni²⁺ species and support. It also removes the weak acidic sites and increases the amount of the strong acidic sites, whereas it decreases the amount of the basic sites. Furthermore, it influences the gaseous products’ distribution by increasing H₂ yield and not favouring the transformation of CO₂ in CO. Thus, a high H₂/CO ratio can be achieved accompanying by negligible value for CO/CO₂. From the liquid products quantitative analysis, it was suggested that acetone and acetaldehyde were the main products for the Ni/Zr catalyst, for 750 °C, whereas for the Ni/SiZr catalyst allyl alcohol was the only liquid product for the same temperature. It was also concluded that the Ni/SiZr sample seems to be more resistant to deactivation however, for both catalysts a substantial amount of carbon exists on the catalytic surface in the shape of carbon nanotubes and amorphous carbon.