Catalytic removal of nitrogen dioxide in the air stream by nickel and nickel- platinum supported multiwall carbon nanotube.

Introduction Nitrogen oxides as one of the most dangerous environmental pollutant, have harmful effects on the health of people in the workplace. Today, the catalytic oxidation of nitrogen oxides is a highly efficient method for removing of this gases  that has been dedicated part of researches. The aim of study was to investigate the removal efficiency of  nitrogen dioxide (NO2) by nickel and nickel-platinum supported on multi-walled carbon nanotubes from air stream in the catalytic oxidation process. Materials and Methods In this experimental study, structural and functional specifications of the catalysts were caracterized by analysis Field Emission Scanning Electron Microscope (FE-SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Temperature-Programmed Reduction (H2-TPR) after stabilization of nickel and nickel-platinum nanoparticles on carbon nanotube substrate. The removal efficiency of the synthesized catalysts were studied at the temperature of 250 °C, space velocities of 15000 – 20000 hr-1 and the NO2 concentrations  of  3000,4000,5000 ppm. Results The results of FESEM  and XRD analysis showed that the diameter of carbon nanotubes ranged from 11 to 18 nm and the size of crystalline nickel and platinum nanoparticle on the catalyst bed were between 10 to 50 nm. The results of catalytic removal of NO2 showed that highest efficiency was related to the condition of  250℃temperature,  the concentration 3000 ppm and the space velocities 20000-15000 per hour. Conclusion According to the acquired results, the use of carbon nanotubes as a catalyst support is appropriate for removal of NO2 fromair stream. Bimetallic catalysts used of nickel and platinum supported on carbon nanotubes was had high efficiency and productivity in NO2 removal at various temperature, retention time, and the concentration of pollutants.