Characterization of none and yttrium-modified Ni-based catalysts for dry reforming of methane

Monometallic and bimetallic RhNi catalysts supported on gamma-alumina and yttria-modified alumina were developed. The relation between the support kind, the structure and catalytic properties of the catalysts in dry reforming of methane was studied by using different techniques such as: N-2 isotherms, UV-vis DRS, XRD, TPDNH3, TPR-H-2, XPS and HRTEM. Variation in the electronic environment of the nickel, rhodium and yttrium atoms as a function of the catalyst pretreatment and support kind was observed. It was shown that the couple pairs of Ni-o/Nin+ and/or Rh-o/Rhn+ act as active sites. The difference in the catalytic behaviors of catalysts was connected with the distribution of metal particles. Y-loaded monometallic Ni catalyst showed higher activity and stability than alumina supported Ni due to the proximity of nickel to yttrium oxide species expressed by the increase of metal dispersity. The close contact between Rh and Ni leaded to better catalytic behavior of bimetallic RhNi/Al catalyst due to the better reducibility of nickel oxide species and homogeneous distribution of the particles with average diameter size of similar to 5 nm.