新型稀土基催化材料微观缺陷对脱硝性能的影响

NOx has become the main focus of the National emission reduction plan in 'The Twelfth Five-Year Guideline',but the core of catalytic technologies to control NOx (denitrification) in China mainly rely on import.Although our country has introduced several catalyst-production lines from abroad， all these catalysts belong to a highly toxic vanadium-titanium system which results in secondary enviromental pollution,and also they have low mechanical strength and poor impact resistance. These drawbacks will limit the application of above deNOx catalysts to the high dust environments in cement and steel industries. This project will be based on our independent self-developed novel rare-earth-based Ce-Ti-Zr-Ox catalyst, the chemical theory of material defects and advanced material characterization techniques will be applied for further studying the effects of micro lattice point defects, surface defects and grain boundary defects on deNOx catalytic activities. The fundamental relationships between the microdefects of materials and deNOx catalytic activity will be explored, and also optimal process conditions and parameters for catalyst preparation will be obtained, which wonderfully combines the materials science and catalytic chemistry and provides new ideas for designing and selecting catalysts with high deNOx catalytic activity. It will provide theoretical bases and technological supports for obtaining the preparation technique of the high efficiency and non-toxic rare-earth-based deNOx catalyst with independent intellectual property.

NOx已成为国家"十二五"减排的重点，但我国治理NOx（脱硝）的核心催化剂技术主要依赖进口，虽东方凯特瑞、江苏龙源等引进了生产线，但均是剧毒的钒钛体系，存在二次污染，且机械强度低，不耐冲击，限制了其在高粉尘浓度的水泥、钢铁行业脱硝的应用。本课题基于自主研发的Ce-Ti-Zr-Ox新型稀土基无毒脱硝催化体系，运用材料缺陷化学理论和先进的表征手段，进一步研究催化材料的微观晶格点缺陷、面缺陷、晶界缺陷对脱硝催化性能的影响，着重解决高催化活性与高机械强度的矛盾，探索催化材料微观缺陷与脱硝催化性能之间的基本规律，实现材料科学与催化化学的有机结合，为设计、筛选新型高效脱硝催化剂提供新思路。为研发具有自主知识产权的高效、无毒新型稀土基脱硝催化剂制备技术提供理论依据和技术支撑。

稀土基脱硝催化剂技术已入选《国家鼓励发展的重大环保技术装备目录》，《国家鼓励的有毒有害原料（产品）替代品目录（2016 年版）》也明确将稀土脱硝催化剂列为替代钒基脱硝催化剂的产品。催化剂组分确定后，材料的微观缺陷是影响催化性能的关键因素。本课题基于自主研发的Ce-Ti-Zr-Ox新型稀土基无毒脱硝催化体系，运用材料缺陷化学理论和先进的表征手段，全面研究了催化材料的微观晶格点缺陷、面缺陷、晶界缺陷对脱硝催化性能的影响，主要研究成果如下：.1) 点缺陷中氧空位缺陷浓度的提高能有效提高稀土基催化剂的脱硝活性。催化剂中氧空位浓度提高会加快氧的迁移率，催化剂的氧化还原性能会提升，化学吸附氧浓度和表面酸量等均会有所提高，反应气体则更容易在催化剂表面吸附反应，脱硝活性尤其是低温脱硝活性得到明显改善。另外，填隙离子缺陷会导致稀土基催化剂酸量、氧化还原能力等性能下降，从而降低催化活性。2) 面缺陷中高能晶面暴露比的适当提高会提升稀土基催化剂的脱硝活性。TiO2高能晶面(001)暴露比提高会造成催化剂晶粒略微长大，其氧化还原能力和化学吸附氧浓度有所提高，结合(001)晶面和(101)晶面的协同催化作用，催化剂脱硝性能有所增强。3) 晶粒越小晶界越多，无定型体是缺陷综合体，无定型结构有利于改善稀土基脱硝催化剂的低温活性。无定型TiO2时，催化剂的比表面积、酸量、氧化还原性能优，低温脱硝活性高；锐钛矿相TiO2时，催化剂高温结构稳定性好，高温脱硝活性好。.以上成果为高效、无毒的新型稀土基脱硝催化材料开发和应用提供了坚实而富有新意的理论基础。研发出的稀土基催化剂脱硝效率>90%，N2选择性达到100%，机械强度高于5 MPa，催化剂成本低于商业钒钛体系的70%。发表相关论文28篇，其中SCI论文18篇；申请国家发明专利18项，其中授权10项；培养研究生26名；获中国专利优秀奖、江苏省科学技术一等奖、中国石油和化学工业联合会技术发明二等奖、中国产学研合作创新成果奖和淄博市重大专利奖各1项。