一锅法合成Ce_xZr_(1-x)O_2固溶体催化剂用于热化学循环分解CO_2制CO

采用一锅蒸发诱导自组装法(EISA)制备了一系列不同铈锆物质的量比的铈锆固溶体催化剂,用TGA研究了其热化学循环分解CO_2制CO的催化性能,并采用XRD、Raman光谱、H2-TPR、XPS、SEM和N_2吸附-脱附等手段对催化剂的物相结构、还原性能和表面化学性质进行了表征分析,用热重分析(TGA)研究了铈锆固溶体对热化学循环分解CO_2制CO的催化性能。结果表明,随着Ce/Zr物质的量比增加,铈锆固溶体催化剂的CO_2高温分解活性先增大后减小。Ce/Zr物质的量比为1的Ce_(0.5)Zr_(0.5)O_2催化剂由于具有较多的晶格缺陷和氧空穴,氧迁移能力强,催化活性高,而Ce/Zr物质的量比为3的Ce_(0.75)Zr_(0.25)O_2催化剂具有相对稳定的氧空穴数,循环稳定性好。循环反应后,所有的催化剂均出现了一定程度的烧结,且富锆固溶体发生了相分离,这可能会影响催化剂的性能。

One-pot synthesis of CexZr1-xO2 solid solution catalysts for the splitting of CO2 to CO via thermochemical cycling

A series of CeO₂-ZrO₂ solid solutions with different Ce/Zr molar ratios were synthesized by one-pot evaporation-induced self-assembly (EISA) method and characterized by XRD, Raman spectroscopy, H₂-TPR, XPS, SEM and N₂ sorption. The catalytic activity of CeO₂-ZrO₂ solid solutions in the thermochemical splitting of CO₂ to CO were investigated by thermogravimetric analysis. The results reveal that with the increase of Ce/Zr molar ratio, the catalytic activity of CeO₂-ZrO₂ in CO₂ splitting increases first and then decreases. The Ce_0.5Zr_0.5O₂ solution with a Ce/Zr molar ratio of 1 exhibits high activity in CO₂ splitting, owing to its abundant lattice defects and oxygen vacancies which can promote the oxygen migration. In contrast, the Ce_0.75Zr_0.25O₂ solution with a Ce/Zr molar ratio of 3 shows the best cyclic stability, due to its relatively stable number of oxygen vacancies. Sintering of particles was observed after the cycling reaction, accompanying with the phase separation in the Zr-rich solid solutions, which may influence the catalytic performance of CeO₂-ZrO₂ solid solutions in the CO₂ splitting.