Abstract:

CeO₂-modified CuO catalyst (xCeO₂-CuO/NF) was successfully synthesized by hydrothermal method through pre-deposition of CeO₂ crystal nuclei on nickel foam substrate. The soot oxidation activity of xCeO₂-CuO/NF was significantly higher than that of the catalyst without addition of CeO₂ (CuO/NF). With the increase of CeO₂ content, the Ce/Cu mass ratio and the intrinsic catalytic activity of the catalyst gradually increased, and finally both of them reached stable. Among them, the catalytic activity of 6.5CeO₂-CuO/NF was the best with the lowest T₅₀ (383℃), which was 32℃ lower than that of the CuO/NF catalyst. The results indicate that the pre-deposition of CeO₂ crystal nuclei can promote the growth of CuO into a nanostructure, which improves the contact efficiency between soot particles and active sites of the catalyst, on the other hand, the formation of Cu _x Ce_1-x O solid solution on xCeO₂-CuO/NF enhances the interaction between Ce and Cu cations. The interaction generates a redox coupling cycle between Ce³⁺/Ce⁴⁺ and Cu²⁺/Cu⁺, prompting the generation and intrinsic activity of active oxygen species. All of these merits greatly improve the catalytic performance of soot oxidation over our as-synthesized catalysts.

Key words: catalyst, solid solution, nanostructure, multiphase reaction, active oxygen species

摘要：

通过在泡沫镍基底上预沉积CeO₂晶核，采用水热法成功合成出泡沫镍负载CeO₂改性CuO催化剂（xCeO₂-CuO/NF），同未加入CeO₂的催化剂（CuO/NF）相比，其碳烟氧化活性显著提高。随着催化剂中CeO₂含量的增加，Ce/Cu质量比不断增大直至趋于平稳，催化剂的催化活性随之提高直至基本不变。其中，6.5CeO₂-CuO/NF的催化活性最好，T₅₀（383℃）最低，比CuO/NF催化剂低32℃。研究结果表明，预沉积CeO₂晶核一方面可促进CuO微纳结构的生长，提高碳烟颗粒与催化剂活性位点的接触效率；另一方面，xCeO₂-CuO/NF中形成的Cu _x Ce_1-x O固溶体增强了铜铈之间的相互作用，通过Ce³⁺/Ce⁴⁺和Cu²⁺/Cu⁺之间氧化还原耦合循环促使活性氧物种的生成，并提升了其本征活性，从而极大地提高了其催化碳烟氧化的能力。

关键词: 催化剂, 固溶体, 纳米结构, 多相反应, 活性氧物种