高稳定三元Cu基催化剂的构建及水煤气变换性能研究

Water–Gas Shift (WGS) reaction, a key process in purifying hydrogen, which is considered to be important in the construction of a modern energy system with low carbon and efficient energy conversion. Catalyst with high catalytic performance plays an important role in the WGS process, for which Cu based catalyst is reported to be effective in catalytic conversion of CO. However, Cu catalyst suffers deactivation due to the sintering of Cu nanoparticles. Herein, in order to develop a Cu–based WGS catalyst with high catalytic performance, SiO2 is utilized to support Cu species for CO activation, followed by the deposition of CeO2-x for H2O dissociation. CuO–SiO2 synergetic interaction, reduction condition on regulating the particle size of metallic Cu (Cu0) and stability of Cu0 and Cu+ are supposed to be investigated. The influence of CeO2-x surface oxygen vacancies on the synergetic interaction between Cu and CeO2-x also needs to be observed. In situ characterization techniques, e.g. DRIFTS and TPSR–MS, are utilized to track the reaction process of WGS reaction, aiming to know the structure-property relationship of the CeO2-x/Cu/SiO2 in WGS reaction. It is expected that the success of this proposal will provide useful both experimental and theoretical information in developing a Cu catalyst with excellent low-temperature activity and high stability for WGS reaction.

水煤气变换(WGS)反应是制取洁净氢气的重要过程，对建设清洁低碳、高能高效的现代能源体系具有重要意义，其关键是高性能催化剂的研发。Cu基催化剂在该反应中表现出良好的CO深度变换性能，但Cu纳米粒子烧结造成的失活是催化剂面临的难题。本项目提出以SiO2为载体对Cu物种进行分散和稳定，从WGS反应机理出发设计催化剂，在SiO2表面稳定负载CO吸附活化中心Cu，再进一步负载H2O解离中心CeO2-x，调节Cu–CeO2协同作用制备高性能CeO2-x/Cu/SiO2催化剂；研究CuO–SiO2相互作用和还原过程对Cu0颗粒尺寸及Cu0和Cu+稳定性影响；考察CeO2-x表面氧空位对Cu–CeO2-x协同作用的影响；利用in–situ DRIFTS、TPSR–MS等技术跟踪反应过程，理解催化剂结构与性能的内在联系。本研究为低温高活性和高稳定性Cu基WGS催化剂的调控和制备提供实验基础和理论支撑。

水煤气变换(WGS)反应是制取洁净氢气的重要过程，Cu基催化剂在该反应中表现出良好的CO深度变换性能。本项目针对Cu基催化剂易发生烧结失活的问题，设计合成了Cu0颗粒尺寸可控、氧空位浓度丰富、Cu0和Cu+稳定且比例可调节的CeO2-x/Cu/SiO2催化剂，并围绕催化剂构-效关系及反应机理展开深入研究。项目取得的主要研究结果如下：1、采用蒸氨-水热法，通过调控制备参数，设计合成了Cu0 颗粒尺寸可控及Cu0 和Cu+稳定的Cu/SiO2催化剂；当Cu负载量为20 wt.%，水热温度150 °C时，Cu/SiO2催化剂具有较高的WGS催化活性；4500 mL·g-1·h-1空速下，250℃时CO转化率大于85%。2、原位表征结果表明，Cu0和Cu+物种对WGS反应过程中的CO吸附和水离解均具有活性，Cu+物种对CO吸附的吸附能力较强，而Cu0物种更有利于H2O的解离，两者的协同作用促进了水煤气变换反应的进行。3、助剂CeO2中Ce4+因部分还原转化为Ce3+而产生氧空位，提高了催化剂对CO吸附和H2O解离能力增强；当CeO2掺杂量为6 wt%时，Cu/SiO2-6CeO2催化剂Cu+物种和表面氧空位数目较多，铜物种颗粒尺寸较小(3.1 nm)，表现出较高的催化WGS反应的活性；4500 mL·g-1·h-1空速下，250℃时CO转化率大于90%。4、N2O氧化预处理对催化剂活性金属Cu的价态具有明显的调控作用；N2O预处理温度越高，催化剂表面的Cu+物种比例越高，从而表现出更高的催化WGS反应的活性；4500 mL·g-1·h-1空速下，经N2O预处理250℃预处理后，CO转化率(250℃)提高了约25%。项目执行期间发表SCI学术论文3篇，申请国家发明专利3件。