温和酸碱活化废弃SCR脱硝催化剂协同提取钒钨新工艺应用基础研究

With the development of economy, a large number of spent SCR (selective catalytic reduction) catalysts will be produced in the power plant of China. The spent SCR catalyst is difficult to effectively recycle, and that led to great environmental pollution and waste of resources. Based on the profound understanding of the physical characteristics of the spent SCR catalyst, a new technological process, which composed of extraction and separation of vanadium and tungsten from spent SCR catalyst by mild acid/alkali activation, and preparation of fresh SCR catalyst from the regenerated TiO2 support, had been proposed in this project. By way of multidisciplinary research method, some key scientific problems, including the reaction mechanism for activation of spent SCR catalyst by mild acid/alkali solution, process control and optimization for the selective and effective extraction and separation of vanadium and tungsten from spent SCR catalyst, the influence factors and the effect mechanism both for the preparation of the fresh SCR catalyst powder from regenerated TiO2 support and for the preparation of honeycomb catalyst from the above powder catalyst, will be deeply investigated. Furthermore, a new method or a novel technology for comprehensive utilization of spent SCR catalyst as TiO2 support and in coordination with effective recovery of vanadium and tungsten from spent SCR catalyst, should be established. Based on the above research results, it will provide sufficient theoretical basis and technical support, both for reducing the operation cost of removing NOx from the flue gases of power boilers or industrial furnaces, and for the achieve efficient recycling of spent SCR catalyst with little environmental pollution.

针对我国电厂烟气脱硝行业即将产生大量废弃SCR脱硝催化剂难以有效回收利用的问题,以及基于对废弃SCR脱硝催化剂物理结构特征的深刻认识，本项目提出了温和酸碱活化废弃SCR脱硝催化剂分离提取钒钨有色金属,以及再生TiO2载体重构制备新鲜SCR脱硝催化剂的新工艺。通过多学科研究方法综合交叉,深入开展废弃SCR脱硝催化剂温和酸碱活化反应机理、钒钨有色金属高效选择性分离提取过程调控与工艺优化、再生TiO2载体重构制备新鲜SCR脱硝催化剂及催化剂成型的性能影响机制等关键科学问题研究，建立废弃SCR脱硝催化剂载体化利用与钒钨有色金属协同提取利用的新方法、新技术，从而为我国烟气脱硝行业降低运行成本、实现废弃SCR催化剂高效再生回收利用提供充足的理论基础与技术支撑。

废SCR脱硝催化剂是烟气治理氮氧化物脱除过程中形成的危险废弃物，年产生量超过30万m3，主要以V2O5为活性组分，WO3为活性助剂，TiO2为载体，三者含量达到95%以上；从废SCR脱硝催化剂中回收V、W、Ti有价金属组分，具有重要的资源环境双重意义。但因废弃SCR脱硝催化剂V2O5含量低等特殊结构与组成，现有回收工艺无法实现V、W高效分离与提纯，TiO2载体未能实现高值重构大掺和比制备新鲜催化剂，整体工艺经济环保效益差。本项目针对上述问题，提出了温和酸碱活化废SCR脱硝催化剂分离提取钒钨金属组分,以及再生TiO2载体重构制备新鲜SCR脱硝催化剂的新工艺。研究内容包括：新工艺活化反应机理、钒钨金属组分高效选择性氧化分离提取过程调控机制与工艺优化、再生TiO2载体重构制备新鲜SCR脱硝催化剂以及催化剂成型性能影响机制等关键科学问题与工艺过程。研究发现：（1）废SCR脱硝催化剂中的V和Fe杂质在草酸体系下实现氧化还原浸出，浸出率达86%和100%；通过循环富集后V元素浓度达到3~5 g/L，酸介质实现90%的循环利用.（2）采用二级氧化分布沉淀过程分离V、W、Ti元素，沉钒率达到97%，偏钒酸铵纯度达到99%，V元素整体回收率达到83%，W元素可和Ti元素同步沉淀，沉淀率达到97%以上，钨酸纯度达到98%。（3）Ti元素通过碱法重构过程以TiO2的形式回收，其中锐钛相结构达到99%以上，比表面积大于90 m2/g，在600 ℃下具有良好的载体热稳定性，杂质元素含量符合脱硝催化剂载体应用要求。回收得到的载体TiO2负载制备得到的新催化剂，在300~450 ℃催化性能达到95%以上，具有良好的抗硫抗水性、成型性及耐磨性。本项目研究在V、W、Ti多金属复杂矿相温和重构基础理论方面取得新进展，突破了TiO2载体高质回收制备新鲜催化剂核心技术基础，形成了废SCR催化剂V、W、Ti多金属清洁循环利用，具有重要的理论意义和应用价值，发表高水平学术期刊论文多篇，申请发明专利9项，技术研究成果应用于合作企业工艺技术升级，得到国家重点研发计划项目支持，将持续拓展研发与应用工作。