Cu-Co oxides supported on porous minerals for catalytic oxidation of butyl acetate: Particle dispersion, catalytic performance, and oxidation mechanism

Natural nanofibrous palygorskite with micropores, nanotubular halloysite with mesopores, and disc-shaped diatomite with macropores exhibit distinct advantages in dispersing metal oxide particles due to their regular porosity, mechanical adhesion, and thermal stability. Three natural porous minerals with typical morphology were employed as supports for Cu-Co oxides in the catalytic oxidation of butyl acetate. XRD and Raman reveal that spinel-structured Cu 0.72 Co 2.28 O 4 and tenorite-structured CuO are main phases on three supports, while SEM and TEM suggest that halloysite and palygorskite are better than diatomite in dispersing Cu-Co oxide particles. Due to high dispersion, superior reducibility, and moderate Co 3+ -O 2- , the halloysite-supported Cu-Co oxides exhibit the lowest T 50 of butyl acetate conversion at 232 °C among three supported catalysts. Natural porous supports modulate the spinel lattice, improve the adsorption of butyl acetate, provide surface hydroxyls in oxidation, and enhance the thermal stability of Cu-Co oxides. The gaseous O 2 supplements the surface chemisorbed oxygen and lattice oxygen, which participate in the complete oxidation of butyl acetate. Above results indicate that natural porous minerals are potential supports to transition metal oxides for VOCs oxidation.