Synthesis of methanol over highly dispersed Cu-Fe based catalysts derived from layered double hydroxides

In this paper, catalysts with different aluminum contents were prepared by a co-precipitation method using LDHs (layered double hydroxides) as the precursors through the adjustment of Cu²⁺ : Fe²⁺, and the catalysts were named LDO catalysts. The effect of aluminum on CO₂ hydrogenation to methanol was investigated by evaluating the characterization. With the addition of Al, Ar physisorption results showed an increase in BET-specific surface area, TEM demonstrated a decrease in catalyst particle diameter, XRD showed that Cu and Fe existed in the catalyst mainly in the form of CuFe₂O₄ and CuO, XPS demonstrated a decrease in electron cloud density and an increase in base sites and oxygen vacancies, and CO₂-TPD and H₂-TPD results indicated that Al promoted the dissociation and adsorption of CO₂ and H₂. When the reaction temperature was 230 °C, the pressure was 4 MPa, H₂/CO₂ = 2.5 and the space velocity was 2000 ml (h g_cat)^-1, the best conversion (14.87%) and the highest methanol selectivity (39.53%) of the catalyst were obtained at 30% aluminum content.