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

To improve the removal capacity of NO + O 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 adsorption properties were determined by means of various techniques. The results show that the sequence in (NO + O) 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) adsorption capacity (106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O on the A-C-FDU-15(x) samples, and (NO + O) adsorption on the samples was mainly chemical adsorption. Combined with the results of (NO + O)-temperature-programmed desorption ((NO + O)-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, we deduced that there were two main pathways of (NO + O) adsorption: one was first the conversion of NO and O to NO and then part of NO was converted to NO and NO; and the other was the direct oxidation of NO to NO and NO.