دانلود رایگان مقاله فوتوکاتالیست الحاق اکسیداسیون کربن همزمان و کاهش NOx

Abstract

Photocatalysis assisted oxidation of carbon black was performed using TiO2 photocatalyst under UV illumination in an atmosphere with NO, O2 and water vapor at 150 °C. Carbon is oxidized mainly to CO2 while NO is selectively converted to N2. Enhanced O2 and NO concentrations have a positive effect on the carbon oxidation rate. At a concentration of 3000 ppm NO and 13.3% O2 in the gas phase the carbon oxidation rate reaches 2.3 μgcarbon/mgTiO2 h, at a formal electron/photon quantum efficiency of 0.019. HR SEM images reveal uniform gradual reduction of the carbon particle size irrespective of the distance to TiO2 photocatalyst particles in the presence of NO, O2 and H2O.

4. Conclusions

Commercial TiO2 (Cristal Global PC500) is active in photocatalysis-assisted oxidation of carbon black with nitric oxide and oxygen in the presence of water vapor at 150 ◦C. Carbon is selectively converted into CO2 while NOx is reduced to N2. Up to 30% of the carbon was oxidized without catalyst deactivation. Uniform size reduction of the carbon particles in the presence of NO, O2 and H2O was observed with HR SEM, irrespective of the distance to TiO2 photocatalytic particles suggesting the involvement of mobile oxidative species. Photocatalysis assistedcarbonoxidationandNOx reductionmay find application in exhaust gas purification. The reduction of NOx selectively to N2 using carbon is a new type of SCR catalysis, coined Photo-C-SCR. The highest observed carbon oxidation rate of 5.64 g carbon per hour per mg TiO2 is much below carbon oxidation rates obtained with thermal catalysts in the temperature range 300–500 ◦C. At low temperature where thermal catalysts are inactive, photocatalysis may be relevant provided activity is further enhanced. Photocatalysis assisted oxidation may be an alternative method for modification of carbon nanoparticles. But more work is needed to explore this idea.