Activities of CeO2/TiO2 Catalyst for SCR of NO with NH3 at Low Temperature According to Operating Conditions

A catalyst based on CeO2/TiO2 was prepared by the impregnation method, and its activities for low temperature selective catalytic reduction (SCR) of NO with NH3 were investigated at temperature from 373 to 573 K. As the cerium oxide loading was increased until 40 wt. %, NO conversion of CeO2/TiO2 catalyst increased significantly, whereas that of the catalyst with 50 wt. % cerium oxide loading decreased due to the change of the main phase. The effects of the operating conditions were also studied at various gas hourly space velocities (GHSV), reaction temperatures, O-2 concentrations and NH3/NO ratios. The reaction temperature has a greater effect on the activity of the catalyst than the GHSV. The lattice oxygen of CeO2 contributes to the SCR of NO with NH3 at low O-2 concentration. When an excess NH3 concentration, further NH3 addition could not improve the NO conversion efficiency due to the limited amount of adsorption sites. The experimental results showed that the best CeO2/TiO2 catalyst yielded more than 92% NO conversion at 523 K at a space velocity of 10,000 h(-1). The reaction orders of NO, NH3, and O-2 were determined to be 1, 0, and 0.5, respectively, and the apparent activation energy was calculated to be 32.5 kJ/mol.