NH3 TPD STUDY AND THERMAL-BEHAVIOR OF VANADIUM-EXCHANGED TITANIUM PHOSPHATES AS CATALYSIS - REDUCTION OF NO WITH NH3

The ion exchange technique was employed for the preparation of VO2+ mo dified titanium phosphates as catalysts for the selective reduction of NO with NH3. The samples were prepared by contacting with a vanadyl s ulphate solution different precursor materials, amorphous, crystalline or sodium half exchanged titanium phosphate. The vanadium contents of modified phosphates were in the range 0.08-2.3 wt%. XRD and thermal a nalysis TG/DTA showed that vanadium loading does not cause structural modification in hydrogen titanium phosphate. A vanadyl containing phas e was obtained when half sodium titanium phosphate was employed. The N H3 TPD measurements indicated the presence of a wide distribution of N H3 adsorbing sites with medium-high strength. Catalytic activity measu rements were performed under dilute conditions. It was found that the presence of vanadium even in low amounts strongly promote the catalyti c activity.