Electronic modulation via asymmetrical heteronuclear sites: unlocking high-performance oxidative dehydrogenation of 1-butene with CO2 over VCaOx–FeAlOx catalysts

Abstract

The activation of CO₂ and the improvement of butadiene (BD) selectivity and BD yield were the two main challenges in the oxidative dehydrogenation (ODH) of 1-butene with CO₂. To address these two issues, we designed a VCaO_x–FeAlO_x catalyst with an asymmetrical structure. The heteronuclear systems precisely regulated the electronic environment of the Fe catalytic centers and notably increased the amount of active lattice oxygen. Furthermore, the introduction of Ca species successfully promoted the desorption of BD from the surface. As a result, the VCaO_x–FeAlO_x catalyst showed a superior BD selectivity and BD yield with low transition-metal content. The roles of V and Ca species were also clearly explained in this study. The DFT results also confirmed that CO₂ undergoes severe distortion when adsorbed on the asymmetrical sites. This enabled the VCaO_x–FeAlO_x catalyst to promote higher CO₂ conversion. Benefiting from this, the VCaO_x–FeAlO_x catalyst exhibited low carbon formation and good catalytic performance. The reaction pathway was also studied by coupling the results with in situ DRIFTS and mass spectrometry analyses. The proposed preparation strategy through the construction of the asymmetrical structure on the support offers a promising solution to the challenges in this field.