The Influence of the Hydrothermal Aging Temperature on CoCuAl Layered Double Hydroxide‐Derived Mixed Oxides for CO ₂ Purification of Industrial Flue Gas

The removal of NO and CO from CO 2 industrial flue gases is achievable using Selective Catalytic Reduction (SCR) of NO by CO over transition‐metal‐based catalysts. In this work, CoCuAl mixed oxides were synthesized via the Layered Double Hydroxide (LDH) co‐precipitation route with hydrothermal aging at temperatures ranging from 40 to 110 °C. The influence of hydrothermal aging temperature on the physicochemical properties was investigated using X‐ray diffraction (XRD), N 2 Physisorption, Raman spectroscopy, H 2 Temperature‐Programmed reduction (H 2 ‐TPR), Fourier‐transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Low to moderate hydrothermal treatment temperatures (40°C–60°C) promote enhanced crystallinity, cation incorporation, and carbonate intercalation within the LDH structure, whereas higher temperatures (> 80°C) induce CuO phase segregation with less anion intercalation. After CO 2 treatment at 400°C, the mixed oxides prepared at low‐to‐moderate temperatures exhibited higher carbonate content and larger surface area (147–132 m 2 .g −1 ). Pearson's Correlation analysis reveals the highest positive impact of carbonate content on NO reduction ( R = 0.94), whereas CuO shows a strong negative relationship ( R = −0.97) with N 2 formation at higher treatment temperatures (> 80°C). These balanced properties, at low‐to‐moderate hydrothermal treatment temperatures, enhance CO oxidation (100% at 260°C) and promote higher N 2 selectivity (51%–57% at 280°C–300°C).