Correlation of MgO loading to spinel inversion, octahedral site occupancy, site generation and performance of bimetal Co–Ni catalyst for dry reforming of CH4

Abstract

The influence of MgO content on the structural characteristics and performance of bimetallic Co–Ni catalyst was investigated for CO2 reforming of CH4. Three different catalysts with the same amount of active metals (Co and Ni) but different Mg loading in the Mg–Al support were prepared by co-precipitation method. The catalysts were subjected to different characterization techniques to obtain information about their bulk, structural, textural properties, site formation and performance for DRM. Results showed there was reduction in the surface area (N2 adsorption), a change from a single bulk phase spinel to dual-phase (XRD), and an increase in the degree of spinel inversion (Al-NMR) from 0.29 to 0.57, as the MgO loading changed from 25% to 65% in the support. There was also improved support basicity (CO2-TPD), metal support interaction changed (STEM EDX), the ease of metal reduction and site formation (Ni/Co K-edge XANES) became better as the MgO loading increased. Improved MgO loading facilitated the formation of inverse spinel and MgO - Ni/Co solid phase, which enhanced better reactants conversion and faster conversion of deposited carbon from the catalysts surface during DRM.