Comparison of NaY-Encapsulated and NaY-Embedded CuO Nanoparticle (Cu/NaY-En and Cu/NaY-Em) Catalysts for the Oxidation of Toluene

The transition Cu metal-loaded zeolite is a promising alternative oxidation catalyst for volatile organic compounds (VOCs) removal. Based on total toluene oxidation, NaY-encapsulated and NaY-embedded CuO nanoparticle catalysts were prepared by one-pot (OP) and initial impregnation (IWI) methods, respectively. Characterization results show that CuO nanoparticles in the Cu/NaY-En catalyst have higher dispersion and smaller particle size than the 10Cu/NaY-Em catalyst (2–4 nm), resulting in stronger interaction between CuO nanoparticles with zeolite. In addition, the relatively high crystallinity, low temperature reducibility, and high content of Cu+ and Lewis acid in the Cu/NaY-En catalyst are also key factors for promoting catalytic activity in this work. Therefore, the Cu/NaY-En catalyst has higher catalytic efficiency than Cu/NaY-Em with preparation optimization. Cu/NaY-En (5 wt % Cu) manifests super-reactivity with T90 (temperature for 90% conversion rate of toluene) of 251 °C, and the value of Cu/NaY-Em (10 wt % Cu) is 278 °C. Especially, Cu/NaY-En exhibits excellent water resistance during toluene reaction. This work is beneficial to the synthesis of catalysts with high catalytic activity for oxidation of VOCs.