Double-Site Doping of a V Promoter on Nix-V-MgAl Catalysts for the DRM Reaction: Simultaneous Effect on CH₄ and CO₂ Activation

A series of V-doped layered double hydroxide-derived Ni x -V-MgAl catalysts were prepared and applied in the dry reforming of methane (DRM) reaction. The catalyst activity was enhanced with increasing amounts of a V promoter and was optimal at Ni/V = 10. Various characterizations showed that an appropriate amount of the V additive was doped in both the Ni sites and the MgAl mixed-oxide support. The addition of the V promoter not only improved the dispersion of Ni sites but also increased their electron cloud density. The activation energy of CH 4 cracking to form CH 3 and H species decreased from 72.1 kJ·mol –1 on pure Ni(111) to 37.1 kJ·mol –1 on V 0.50 Ni(111). Meanwhile, the adsorption and activation abilities of CO 2 were affected by the insertion of V species in the MgAl mixed-oxide support. In situ CO 2 infrared spectrometry verified that the addition of the V promoter inhibited the formation of nonactivated multidentate carbonate and significantly increased the content of the monodentate carbonate species, which was considered as the intermediate of CO 2 activation. Thus, the enhanced CO 2 activation ability of the Ni 10 -V-MgAl catalyst suppressed the generation of carbon deposits during the DRM reaction, thereby achieving excellent stability in long-term testing compared to undoped Ni-MgAl.