Synthesis of Zeolitic Ti, Zr-Substituted Vanadotungstates and Investigation of Their Catalytic Activities for Low Temperature NH<sub>3</sub>-SCR
Meilin Tao, Satoshi Ishikawa, Zhenxin Zhang, Toru Murayama, Yusuke Inomata, Akiho Kamiyama, Ichika Nakaima, Yuan Jing, Shinya Mine, Kosuke Shimoda, Takashi Toyao, Ken‐ichi Shimizu, Wataru Ueda
Abstract
Microporous vanadotungstate (W4V3O19, VT-1) was constructed via the connection of [W4O16]8– cubane units with VO2+ linkers to form an LTA-zeolite-type crystal structure. We found that the VO2+ sites connecting the cubane units of VT-1 could be partially removed by an appropriate acid treatment without destroying its crystal structure. This process involved a redox reaction between the [W4O16]8– cubane units and VO2+ linkers, and V was removed as V5+ during the acid treatment. TiO2+ or ZrO2+ could be introduced into the VO2+ vacancies. The introduction of Ti or Zr substantially improved the thermal stability of VT-1 under oxidizing conditions. The catalytic activity toward the selective catalytic reduction of NOx with NH3 (NH3-SCR) was improved by the introduction of Ti or Zr.