Study on Ti-Sn Solid Solution Supported Catalyst for Selective Catalytic Reduction of NOx with NH3

TiO₂-SnO₂ solid solution supports was prepared by coprecipitation method with different SnO₂ content (molar fraction) and calcination temperature and V₂O₅ was loaded on the supports to obtain V₂O₅/ TiO_1-xSn_xO₂ catalysts by wet-impregnation method. The support and catalyst were characterized by X-ray diffraction (XRD) and BET and their catalytic performances for the selective catalytic reduction of NO_X with NH₃ were investigated on in a quartz tubular fixed-bed microreactor to compare preparation methods of solid solution on the catalytic activity of De-NO_x. The study indicates that different ratios of SnO₂ to TiO₂ can form continuous solid solution which has rutile crystal structure. The particle size of the solid solution is smaller than that of pure TiO₂ or pure SnO₂. The change of the surface area of the SnO₂-TiO₂ solid solution with the SnO₂ or TiO₂ content is a volcano shape curve and the solid solution with 50% SnO₂ content has largest BET surface area and highest De-NO_x activity. Rutile crystal structure begins to appear in the SnO₂-TiO₂ solid solution calcined at 450°C and replaces anatase phase more as calcination temperature rises and no anatase crystal structure can be detected at 700°C according to XRD result. The BET surface area of solid solution and catalysts declines with higher calcination temperature, either. De-NO_x activity V₂O₅/ TiO_1-xSn_xO₂ shows the same trend. V₂O₅/ TiO_1-xSn_xO₂ catalyst calcined at 450°C comprises both anatase and rutile phase of TiO₂, showing higher thermal stability, larger surface area and stronger De-NO_x activity, while 1% V₂O₅ loading supported on TiO_0.5Sn_0.5O₂ solid solution is highly active for NO removal.