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

Highlights: • The oxides mixture containing NiO, ZnO, Al₂O₃, NiAl₂O₄ and ZnAl₂O₄ was detected. • The results exhibited intermediate interactions between Ni0 and other phases. • Dry reforming of methane was applied to production of synthesis gas. • Deposition of the carbon filamentous on the catalysts surface was observed. - 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.