Reaction Analysis of Carbon Deposition in Carbon Dioxide Reforming by ab Initio Molecular Orbital Study

Abstract

In the CO₂ reforming reaction using CH₄, carbon precipitation on metal catalysis takes place making the catalysis inactive and useless. In this study, we have suggested two reaction pathways of carbon deposition process on Pd8 (111) cluster in CO₂-CH₄ reforming reaction, which are i.e. Path 1 and Path 2, shown below;
Path 1
       CO+^* → CO-^*
       CO-^*+CO → C-^*+CO₂
Path 2
       CO+^*+^* →  C-^*+O-^*
       O-^*+CO → CO₂+^*
   where ^* is a adsorption site on a catalysis.
The results obtained in the analysis of these two reaction pathways using ab initio molecular orbital method are as follows: (1) energy profile diagrams of those reaction pathways to elucidate the preferred pathway of carbon deposition and (2) electron transfer and population analysis from and to the Pd cluster. Through this analysis, Path 2 appears the preferred reaction path in the present carbon precipitation reaction scheme.