固体电解质基阻抗型氨气传感器的研究

Removal of NOx in exhaust gases is a critical problem to be solved. Selective catalysis reduction of NOx using NH3 is one of the advanced technologies of removal of NOx. In order fully to remove NOx and control NH3 slip in narrow range, the treatment process require to be monitored by NH3 sensors, so it is very urgent to develop NH3 sensors which possess excellent properties, such as, high sensitivity, good selectivity and on-line operating. In this proposal, a planar impedancemetric NH3 sensor will be fabricated based on La10(SiO4)6O3 based electrolyte. The research work includes: (1) effect of partial substitution of alkali metal for La in La10(SiO4)6O3 on its phase composition, conductivity and sinterability will be studied and high performance electrolyte is obtained; (2) preparation process of nano-structured sensing materials in porous electrolyte layer is optimized and the fabrication process of impedancemetric NH3 sensors is established; (3) sensing properties and responding mechanism of the sensors will be investigated with phase angle as sensing signal. The relationship between sensor performance and sensing material composition, sesning material morphology and micro-structure of three-phase boundary will be determined; (4) the sensor selectivity will be improved by background deduction technique, reference electrode selection or applying bias current and so on. By proposal research work, some science questions involving in electrolyte properties and sensing behaviors of the NH3 sensors will be understood and the impedancemetric NH3 sensors with high performance will be acquired.

废气脱硝是亟待解决的问题。用NH3选择性催化还原氮氧化物是先进的脱硝技术之一。为监控催化剂的工作效率，避免NH3过量造成二次污染，开发灵敏度高、选择性好、能在线监测NH3的传感器就变得极为迫切。本项目拟制备平面阻抗型NH3传感器，研究: (1)对La10(SiO4)6O3电解质进行La位碱金属掺杂，探索元素种类及掺杂量等对其相组成、电导率和烧结性能的影响规律，获得高性能电解质; (2)在电解质多孔结构中原位制备纳米尺寸、高分散的敏感电极材料，建立阻抗型NH3传感器的制备工艺; (3)以相角为敏感信号，研究传感器的敏感性能及响应机制，建立敏感材料组成、形貌和三相界面结构与传感器性能间的关系; (4)通过背景扣除技术、参比电极选择或施加偏电流等方法，显著提高传感器的选择性。通过研究，探明与La10(SiO4)6O3基电解质及NH3传感器性能等相关的科学问题，获得高性能阻抗型NH3传感器。

以NH3为还原剂，选择性催化还原废气中氮氧化物是先进的脱硝技术之一。为保证氮氧化物去除完全，监控催化剂的工作效率，避免NH3造成二次污染，必须使用NH3传感器对脱硝过程进行检测，因此，开发响应快、灵敏度高、能在线监测NH3传感器具有重要意义。本项目采用固态反应法制备了La位碱金属掺杂的La10(SiO4)6O3电解质，探索了元素种类及掺杂量等对其相组成、微观结构、电导率和烧结性能的影响规律，获得了烧结性能好、电导率高的材料体系，其电导率提高了2-4倍，离子迁移数大于0.99。采用浸渍热分解法、脱混法、化学脱溶法和电化学脱溶法等技术，在多孔电解质内原位制备和修饰敏感电极，探明了敏感电极制备的物理化学条件。以双层结构的硅酸镧或YSZ为电解质，组装平面阻抗谱型NH3传感器，探讨了复合敏感材料组成，微观形态，三相界面结构等对传感器性能的影响，获得了多个有前景的敏感体系，实现了其在灵敏度、响应速度、抗干扰和长期稳定性等性能的提高。通过敏感材料选择、第二相修饰、参比电极的优化和敏感电极非化学计量元素掺杂，改善了传感器选择性，揭示了影响传感器选择性的因素和机制。通过研究，初步弄清了在传感器制备和响应中的一些关键科学问题，在敏感电极性能调控和响应机理研究方面形成新知识，为敏感电极的设计与合成提供理论依据。将上述思想和方法进行延伸和扩展，本工作还成功地制成了新型NOx传感器，取得了满意结果。本项目实施过程中，发表相关期刊论文21篇，其中SCI收录20篇，获得国家发明专利1项。培养博士研究生3名，硕士研究生9名。指导的1名学生获得河北省优秀硕士论文。项目投入经费62.00万元，支出经费38.16万元，结余经费23.84万元，各项支出基本与预算相符，剩余经费将用于本项目研究后续研究。