摘要
对钒钨钛(V-W-Ti)催化剂进行Ce掺杂制备了CexV1W7/Ti(x%为CeO2负载量,以催化剂总质量计,下同),采用XRD、N2吸附-脱附、SEM、XPS、FTIR对其进行了表征,通过NH3/NO-TPD表征了NH3和NO在催化剂表面的吸附强弱分布,并测试了不同CeO2 负载量下催化剂的脱硝性能,经密度泛函理论计算探究了催化剂的失活机理.结果表明,CeO2 的负载增加了催化剂表面化学吸附氧的比例和Brønsted酸性位点,减少了催化剂表面V4+的比例和Lewis酸性位点;适当的CeO2负载量能显著提高V-W-Ti催化剂的中低温活性,但负载量过多会降低催化剂的高温活性,CeO2 负载量为 1%的钒钨钛催化剂(Ce1V1W7/Ti)表现最佳,其在全温度(200～400℃)段的脱硝活性均优于V-W-Ti,在260℃,空速为6×104 h-1的反应条件下,NOx脱除率从79.01%增至99.19%,在含有H2O、SO2的气氛中,其NOx脱除率从58.33%升至74.55%.Ce的掺杂降低了催化剂表面氧空位的形成能,改变了催化剂表面的酸位强弱,强化了 SO2 在催化剂表面的吸附,SO2 中毒后的催化剂表面会沉积硫酸铵盐,在H2O的协同作用下,Ce掺杂后催化剂表面更易沉积硫酸铵盐,这是催化剂失活的主要原因.
Abstract
CexV1W7/Ti(x%refers to the CeO2 loading,based on the total mass of catalyst,the same below)was prepared by Ce doping of vanadium,tungsten and titanium(V-W-Ti)catalyst and characterized by XRD,N2 adsorption-desorption,SEM,XPS and FTIR.The adsorption strength distribution of NH3 and NO on the catalyst surface was characterized by NH3/NO-TPD.The influence of CeO2 loading on the denitrification performance of the catalyst was investigated,while the deactivation mechanism was analyzed by density functional theory calculation.The results showed that the CeO2 loading increased the chemisorbed oxygen ratio and Brønsted acid sites,but decreased the V4+ratio on the catalyst surface and which was the main reason for catalyst deactivation.
基金项目
江苏省科技成果转化专项资金项目(BA2022073)
清洁高效燃煤发电与污染控制国家重点实验室开放课题(D2022FK076)
NETL
NSTL
万方数据