VANADIUM-TITANIUM OXIDE AEROGEL CATALYSTS

Selective catalytic reduction of nitric oxide by ammonia in the presen ce of oxygen was studied over titania-supported vanadia aerogels promo ted by the addition of cerium oxide and tungsten oxide. Conversion of NO by NH3 was determined for temperatures ranging from 423 to 723 K at a space velocity of 200 000/h (NTP). The highest activity (95% conver sion) was observed for a W/V/Ti(1.0/7.5/97.5 at.%) aerogel at 723 K. T he best activities for the Ce/V/Ti (0.1/2.5/97.5) and V/Ti (2.5/97.5) aerogels were 89% and 83% conversion respectively at 723 K. Arrhenius plots gave an activation energy of 42-71 kJ/mol dependent on catalyst investigated. Surface groups identified by Fourier transform infrared (FTIR) characterization demonstrated strong absorption bands of nitric oxide on pre-reduced surfaces. Both strong Lewis and weak Bronsted ac id sites were detected by ammonia adsorption on pre-oxidized samples c ontaining vanadium, cerium, and tungsten.