Pd-W-Cu/γ-Al_2O_3催化氢还原脱硝的基本性能研究

Fundamental properties of Pd-W-Cu/γ-Al_2O_3 for catalytic denitrification of ground water by hydrogenation reduction

采用浸渍法制备Pd-W-Cu/γ-Al2O3催化剂,用XRD和SEM方法对该催化剂进行了表征.以氢气作为还原剂,在间歇式反应器中对催化还原地下水中硝酸盐进行了实验研究,考察了催化剂制备方法对催化还原硝酸盐性能的影响.结果表明,W的添加改善了Pd的分散性,提高了催化剂的活性和选择性.金属Pd/W/Cu质量比、浸渍顺序和焙烧温度对催化性能有较大影响.Pd/W/Cu质量比为3∶1∶1,Pd、Cu和W3种金属组分同时浸渍,焙烧温度为400℃时,催化剂的活性和选择性最高.在NO3--N初始浓度为100mg·mL-1条件下,催化反应60min后水中NO3--N和NO2--N浓度均为0mg·mL-1,NH4+-N浓度为2.5mg·mL-1.

A Pd-W-Cu/γ-Al2O3 catalyst was prepared by impregnation and characterized by X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The catalytic reduction of nitrate in ground water by the catalyst was experimentally studied using hydrogen as reducing agent in a batch reactor.The effects of preparation procedures and conditions on the performance of the catalyst were investigated.The results showed that addition of W improves the dispersity of Pd and promotes the activity and selectivity of the catalyst.The Pd/W/Cu mass ratio,impregnation sequence,and calcination temperature have great effect on the properties of the Pd-W-Cu/γ-Al2O3 catalyst.The catalyst exhibits higher activity and selectivity under the optimal conditions of a Pd/W/Cu mass ratio of 3∶1∶1,simultaneous impregnation of Pd,W and Cu,and a calcination temperature of 400℃.For a sample with an initial concentration of NO3^--N of 100 mg·L^-1,after reaction for 60 min the concentration of NO-3-N dropped to 0 mg·L-1,the concentration of NO2^--N was 0 mg·L^-1 and the concentration of NH＋4-N was 2.5 mg·L^-1.