Adsorption performance of CMK-3 and C-FDU-15 in NO removal at low temperature

CMK-3 and C-FDU-15 samples were synthesized using hard-templating and evaporationinduced self-assembly(EISA)methods,respectively.The pore structures of CMK-3 and CFDU-15 as well as commercial activated carbon were characterized by means of X-ray diffraction,field emission scanning electron microscopy,transmission electron microscopy,and N2 adsorption–desorption.Adsorption of NO was investigated by means of thermogravimetric analysis,temperature-programmed desorption of NO+O2,and in situ diffuse reflectance Fourier transform infrared spectroscopy.The results show that the CMK-3 and C-FDU-15 materials possessed ordered and uniform structures.The coadsorption capacity of NO and O2 decreased in the sequence CMK-3(88.6 mg/g)>C-FDU-15(71.7 mg/g)>AC(25.3 mg/g).There were two main adsorption species on CMK-3 and CFDU-15:nitrite and nitrate.Nitrite is converted to nitrate easily.However,the adsorption species were more complex on AC,with nitrite being the main species.Moreover,CMK-3 and C-FDU-15 exhibit excellent regeneration efficiency compared with AC.The excellent NO adsorption performance of CMK-3 and C-FDU-15 was associated with their ordered mesoporous structures and high surface areas.The research provides more options for NO adsorption in the future.

Low-temperature(NO + O_(2)) adsorption performance of alkaline earth metal-doped C-FDU-15

To improve the removal capacity of NO + O_(2) effectively, the alkaline earth metal-doped order mesoporous carbon(A-C-FDU-15(0.001)(A = Mg, Ca, Sr and Ba)) and Mg-C-FDU-15( x)( x = 0.001-0.003) samples were prepared, and their physicochemical and NO + O_(2) adsorption properties were determined by means of various techniques. The results show that the sequence in(NO + O_(2)) adsorption performance was as follows: Mg-C-FDU-15(0.001)(93.2 mg/g) > Ca-C-FDU-15(0.001)(82.2 mg/g) > Sr-C-FDU-15(0.001)(76.1 mg/g) > Ba-C-FDU-15(0.001)(72.9 mg/g) > C-FDU-15(67.1 mg/g). Among all of the A-C-FDU-15(0.001) samples, Mg-C-FDU-15(0.001) possessed the highest(NO + O_(2)) adsorption capacity(106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O_(2) on the A-C-FDU-15( x) samples, and(NO + O_(2)) adsorption on the samples was mainly chemical adsorption. Combined with the results of(NO + O_(2))-temperatureprogrammed desorption((NO + O_(2))-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS) characterization, we deduced that there were two main pathways of(NO + O_(2)) adsorption: one was first the conversion of NO and O_(2) to NO_(2) and then part of NO_(2) was converted to NO_(2)^(-) and NO_(3)^(-);and the other was the direct oxidation of NO to NO-2 and NO_(3)^(-).