Anionic starch-induced Cu-based composite with flake-like mesostructure for gas-phase propanal efficient removal

Highly crystalline flake-like CuCeO_2-δ composites (strCCx) with large specific surface area and developed mesoporosity were prepared using an economic and effective bio-template route. Modified starch with abundant surface carboxyl groups was adopted as the chelating agent and template for metal cations immobilization via electrostatic attraction predominately based on the process of -COO^-⋯Cu²⁺ and -COO^-⋯Ce³⁺. Physicochemical properties of prepared materials were systematically explored by FT-IR, XRD, TG, N₂ adsorption/desorption, FE-SEM, TEM, H₂-TPR, O₂-TPD, XPS, DRUV-Vis, and XAFS techniques. Propanal as a typical oxygen-contained VOC was adopted as the probe pollutant to evaluate the catalytic performance of synthesized materials. Characterization results reveal that plenty of copper ions in composite oxides are incorporated into CeO₂ lattice, which produces oxygen vacancies and enhances metal reducibility. Both specific surface area and pore volume of strCCx samples decreased with the increasing of Cu loading. The flake-like CuCeO_2-δ sample (Cu/(Cu+Ce)=0.15) with highest specific surface area (108.2m²/g) and surface oxygen concentration is indentified as the most active catalyst with propanal totally destructed at 230°C. The introduction of H₂O has a negative effect on propanal removal, and the synthesized catalyst has high tolerance to moisture. In conclusion, the specific surface area and surface oxygen density are two vital factors governing the catalytic activity of composite catalysts.