The concentration of nitrate in groundwater of China is now getting higher in many areas, which will cause eutrophication and health risks of human beings. Prof. Cao Hongbin and his research group from Institute of Process Engineering, Chinese Academy of Sciences, developed novel catalyst for groundwater denitration, which showed good performance in batch reactor in experiments of laboratory scale. The results of this work were recently published on Environmental Sciences & Technology 2011, 45: 4066-4072.

Amorphous silica alumina (ASA) was adopted as the support and the catalysts were synthesized with conventional impregnation or deposition method. The Pd-Cu bimetallic nanoparticles supported on catalysts showed very narrow size distribution and very high dispersion, according to TEM results, thus showed high catalytic activity. The reaction selectivity over Pd-Cu/ASA was 91%, much higher than alumina supported catalysts. The reason of gradual deactivation of catalysts in solution was also studied. Nano Metal particles gradually aggregated on the surface after a few cycles of reaction according to the structure and surface characterization results, which cut down the exposure of active sites. Metal Leaching was very little on this kind of catalysts. 

The support plays a key role in determining the catalytic performance of denitration catalysts. ASA supported catalysts showed high activity and selectivity, but the stability is insufficient. The next object of this work is to enhance the stability of these catalysts.

The work was supported by China Postdoctoral Science Foundation (20090460527), National Natural Science Foundation of China (20607023), the Water Pollution Control and Management Project (2009ZX07529-004-3), Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (Grant No. 2009G2-28).