调控Cu/CeO_(2)催化剂形貌增强低温CO氧化的耐水性

Regulating the morphology of Cu/CeO_(2)catalysts to enhance their water-resistant for low temperature CO oxidation

合成了管状、棒状和颗粒状的Cu/CeO_(2)的催化剂,探讨了其在潮湿条件下氧化CO的结构-性能相关性.结果表明,管状催化剂(CuCe-NT)具有优异的低温活性和抗H_(2)O稳定性.根据表征,CuCe-NT与纳米棒状(CuCe-NR)和纳米颗粒状(CuCe-NP)催化剂相比,结晶度更低、表面积更大且结构缺陷更多,从而增强了CuO_(x)与CeO_(2)间的相互作用,加强了Ce^(4+)/Ce^(3+)和Cu^(2+)/Cu^(+)的氧化还原循环,使表面富集大量Ce^(3+)和Cu^(+),进一步促进了CO的吸附和氧化.此外,中空结构的CuCe-NT具有较大的孔径,可有效抑制H_(2)O的缔合吸附,从而抑制氧空位上惰性OH的生成,在潮湿条件下保持较高的氧化性.In-situ DRIFTS表明,相比于CuCe-NP,中空结构的CuCe-NT可以缓解H_(2)O与CO的竞争性吸附,抑制桥式碳酸盐的形成,确保在潮湿环境下氧化CO.本研究从吸附H_(2)O的类型和反应机理方面证明了催化剂结构对耐H_(2)O性的影响,为设计耐H_(2)O性CO氧化催化剂提供了一种策略.

Herein,tube-,rod-and particle-like Cu/CeO_(2)catalysts were synthesized and their structure-performance relationship for CO oxidation in moist conditions was explored.The results revealed that the tube-like catalysts(CuCe-NT)exhibited excellent low-temperature activity and superior H_(2)O resistance stability.The characterization results indicated that CuCe-NT catalyst had a lower crystallinity,larger surface area and more structural defects in comparation with rod-like(CuCe-NR)and particle-like(CuCe-NP)samples,which greatly strengthened the interactions between CuO_(x)and CeO_(2),thus boosting the redox of Ce^(4+)/Ce^(3+)and Cu^(2+)/Cu^(+),and the surface enrichment of Ce^(3+)and Cu^(+),further facilitating the CO adsorption and oxidation.Moreover,the hollow structure of CuCe-NT catalyst with a large pore size effectively inhibited the associatively adsorption of H_(2)O,suppressing the generation of inert OH groups on oxygen vacancies,and thus maintaining its higher oxidization in the presence of water.In situ-DRIFTS showed that compared to CuCe-NP catalyst,the nanotube structure of CuCe-NT catalyst alleviated the competitive adsorption of H_(2)O with CO,and inhibited the formation of bridged carbonates,thus ensuring the CO oxidation under humid atmosphere.This study revealed the effect of catalyst structure on its resistance of H_(2)O in terms of H_(2)O adsorption type and reaction mechanism,thus providing an ingenious strategy for the design of H_(2)O-resistant CO oxidation catalysts.