Biogas reforming over Ni catalysts dispersed in different mixed oxides containing Zn2+, Al3+ and Zr4+cations

Abstract

The active phase plays an important role in the catalytic activity. However, its applicability is directly associated with other present phases in the mixture. In view of this, we report the performance of Ni catalysts dispersed on mixed oxides containing Zn2+, Al3+ and Zr4+cations in biogas reforming. For this purpose, the samples were characterized by X-ray powder diffraction, which showed the formation of a homogeneous mixture of binary (NiO, ZnO, ZrO2 and Al2O3) and ternary (NiAl2O4 and ZnAl2O4) oxides. The temperature-programmed reduction (H2-TPR) provided information on the catalyst reduction. The performance of the catalysts was evaluated using two reduction temperatures (650 °C and 750 °C). The reactions were carried out at 750 °C, where the Ni/ZnAlZr catalyst presented the highest CO2 conversion attributed to the basic sites, which favored the CO2 adsorption. Otherwise, the Ni/ZnZr catalyst (reduced at 650 °C) showed a high CH4 conversion. The catalysts were also reduced at 750 °C and a lower conversion of both reactants (CH4 and CO2) was observed. We argued that the agglomeration process during the reduction condition deteriorates the performance of the catalysts reduced at 750 °C.