(583ca) Low Temperature Catalysts for Direct Remediation of NH3 Malodor in Air

Malodor is an important class of air pollution that has a serious threat to health and quality of life. Ammonia, which is found in waste treatment and handling facilities, landfills and indoor at lavatories and wet markets, is one of the major causes of malodor complaints in the world.

Researchers have developed different ways to remove NH₃ gas, e.g. burning at a higher temperature, using various adsorbents and adopting proper catalysts. However, Burning uses too much energy while the NH₃ conversion is comparative low. A major problem of using adsorbent is the shorter duration time and the high cost of repeatedly replacing new adsorbent after a period of time. This works explores a solution to the malodor influence of NH₃ by finding a suitable catalyst which can convert NH₃ to N₂ easily with a low reaction temperature, humid atmosphere and a high conversion.

In our study, Vanadia-UV100 (V₂O₅-TiO₂) series catalysts are prepared to treat NH_3, as Vanadia is known to have a good catalysis performance to convert NH3 and H2S. Here we use rotary evaporation to obtain Vanadia-UV100 powder from a suspension of UV100 and Ammonium Vanadate in DDI water. These series of catalysts are tested via reactions with a wide concentration range of NH₃ from 50ppm to 4370ppm in air. The results show that they give a perfect conversion rate at low concentrations of NH₃ and an outstanding reaction rate at high concentrations even at lower temperatures such as 30^oC to 75^oC. Through measurements of XRD, Micro-Raman shift, TEM, XPS, the Vanadia-UV100 catalysts are further analyzed, the kinetics and thermodynamics data calculated and collected from the experiments results. The E_A of the reaction is dramatically decreased with an increasing ratio of VO_x/TiO_x. For most catalysts, their performance fell dramatically with a humid setting during the reaction. To solve this problem, Vanadia-UV100 is incorporated into TMOS Alcogel. The obtained mesoporous Aerogel has a strong moisture-resistant ability which allows the catalysts to be water-proof.