The Role of Metal Ion Impregnation on TiO2-ZrO2 Binary Oxide in Ammonia Adsorption

• Main Authors: Nurul Alvia Istiqomah, 艾諾如
• Other Authors: Chang, Sue-Min
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/c8f2h8

碩士 === 國立交通大學 === 環境工程系所 === 107 === Four types of transition metal ions, including copper (Cu), nickel (Ni), tungsten (W), and zinc (Zn), were selected to be impregnated on the porous TiO2-ZrO2 (TZ) binary oxide with an impregnation method and the roles of those transition metals in the surface acidity and ammonia adsorption of the oxides were systematically examined and clarified. The TZ and the impregnated powders (TZM, where M means the impregnated ions) maintained the porous structure and high surface areas (174-188 m2/g) up to 600oC. While all the impregnated ions incrased the Lewis acidity of the TZ substrate, the Cu and Zn species additionally increased the Bronsted acidity as the result of structural mismatch between the tetrahedral Cu and Zn species and the octahedral Ti and Zr species. The W and Ni spcecies, which had high coordination numbers, consumed surface OH groups, thus introducing Lewis acidity primarily. The ammonia adsorption capacity was in the order of TZCu> TZZn> TZNi> TZW> TZ powders. The additional OH groups on the Cu and Zn ions were the major contributor to the high ammonia adsorption of the TZCu and TZZn adsorbents. The TZCu powder showed the highest ammonia adsorption capacity of 1.81 mmol/g at the surface Cu/(Ti+Zr) atomic ratio of 6 10-3. Over this critical Cu concentration, cross condensation between the Cu-OH groups decreased the active sites for the adsorption. The adsorption capacity of the TZCu powder decreased by 26.8% after high-temperatured desorption as the consequence of elimination of OH groups from the Cu ions. However, the loses of adsorption sites were able to be recovered by exposinig the used adsorbent in the ambient air. The high ammonia adsorption capacity, a wide range of acidity strength, and good structural stability enable the impregnated TZ powder to be a promising adsorbent for ammonia removal in variety of industries.