催化裂化再生烟气新型助燃催化剂的研究

In the catalyst regeneration process during the fluid catalytic cracking (FCC), the regeneration flue gas contains a large amount of CO due to the incomplete combustion of the coke. It is one of the major pollutants in the refineries. New non-precious metal supported perovskite catalysts were developed to replace conventional Pt-based precious metal catalyst for CO combustion in the project. In the perovskite complex oxide catalyst system, A site is the rare earth metal and B site is transition metal ion. Cerium-zirconium oxide is used as a carrier with excellent oxygen storage - releasing oxygen performance. The nano-composite oxides, which have "particle diameter matching " effect and high temperature stability, were designed and prepared. This catalyst can not only efficiently oxidize CO completely, but also promote the catalytic reduction of NOx, attrbuting to the rich oxygen vacancies and defects of the perovskite oxides after the part substitution of A and B-site. Thereby the regenerated flue gas pollution for the environment was removed. Furthermore,by means of DFT theoretical calculations and in situ IR & Raman dynamic characterization, the role of the supported nanometer perovskite oxide catalyst was investigated on the molecular and atomic level under the FCC regenerator flue gas conditions. According to the theoretical calculation and experimental results, the active site and the active intermediate species were determined in the catalytic reaction process. It will provide a scientific basis to design the highly efficient catalyst for promoting the combustion of the FCC regeneration flue gas.

在流化催化裂化(FCC)催化剂的再生过程中，由于焦炭的不完全燃烧，再生烟气中含有大量的CO，是炼油厂的主要污染源之一。本项目开发一种新的非贵金属催化材料，采用担载钙钛矿复合催化剂取代传统的Pt基贵金属CO助燃剂。该催化体系以A位稀土金属和B位过渡金属离子组成的钙钛矿复合氧化物为活性成分，以优异储氧-释放氧性能的铈锆氧化物为载体，设计和制备具有"粒径匹配"效应的耐高温纳米复合氧化物，不仅可以有效地使CO完全燃烧，而且利用A、B位部分取代后钙钛矿复合氧化物中的丰富氧空位和缺陷，促使NOx的催化还原，从而消除了再生烟气对环境的污染。进一步通过DFT理论计算与催化剂的原位IR和原位Raman等原位、动态表征实验结果相结合，在分子、原子水平上探讨FCC再生烟气条件下担载纳米钙钛矿氧化物催化剂的作用，确定催化剂的可能活性位及活性中间物种，为高效FCC再生烟气助燃催化剂的设计提供科学依据。

在流化催化裂化(FCC)催化剂的再生过程中，由于焦炭的不完全燃烧，再生烟气中含有大量的CO，是炼油厂的主要污染源之一。本项目开发一种新的非贵金属催化材料，采用担载钙钛矿复合催化剂取代传统的Pt基贵金属CO助燃剂。该催化体系以A位稀土金属和B位过渡金属离子组成的钙钛矿复合氧化物为活性成分，以优异储氧-释放氧性能的铈锆氧化物为载体，设计和制备具有“粒径匹配”效应的耐高温纳米复合氧化物，不仅可以使CO完全燃烧最低下降到120℃，而且催化剂在800℃高温焙烧12后不失活。利用A、B位部分取代后钙钛矿复合氧化物中的丰富氧空位和缺陷，还能促使NOx的催化还原，从而消除了再生烟气对环境的污染。进一步通过DFT理论计算与催化剂的原位IR和原位Raman等原位、动态表征实验结果相结合，在分子、原子水平上探讨FCC再生烟气条件下担载纳米钙钛矿氧化物催化剂的作用，确定催化剂的活性位及活性中间物种，发现反应在低温阶段和高温阶段遵循不同的反应机理，为高效FCC再生烟气助燃催化剂的设计提供科学依据。