关键词: 二氧化碳, 加氢, 低碳烯烃, 铟基氧化物, 催化剂

Abstract:

Synthesis of light olefins directly from carbon dioxide is one of the most efficient approaches for utilizing CO₂ resources and mitigating carbon emissions. InZr oxide is an excellent choice for CO₂ activation component of bifunctional catalyst. A series of In-based oxides with different In/Zr were synthesized by co-precipitation method. The CO₂ hydrogenation performance over the bifunctional catalysts composed of InZr binary oxides and SAPO-34 zeolites was investigated. A CO₂ conversion of 34.9% with a C₂—C₄ olefins selectivity of 70.9% (CO free) was achieved as the In/Zr was 2. The structure and reduction properties of the binary oxides were characterized by X-ray diffraction (XRD) and temperature-programmed reduction (H₂-TPR). The results indicate that the bcc-In₂O₃ phase is the main active oxide component for CO₂ hydrogenation, and the introduction of Zr enhances the structural stability of the oxides. In addition, the influence of mixing manner on the performance of the bifunctional catalyst was also investigated. The bifunctional catalyst prepared by mixing in powder state shows a state of oxide adhering to the surface of zeolite particles, which would hinder the diffusion of methanol. However, excess reactants will inhibit the formation of carbon deposits in zeolites. Finally, the effects of reaction temperature, pressure, space velocity and H₂ or CO₂ in reactant on the reaction performance and the stability of the bifunctional catalysts were investigated.

Key words: carbon dioxide, hydrogenation, light olefins, Indium-based oxide, catalyst