Unusual adsorption and desorption behaviors of NO and CO on nanoporous nickel phosphate VSB-5: In situ FT-IR and TPD study

•Nickel phosphate VSB-5 is firstly used as active compound for NO and CO adsorption.•The surface state in the pore of VSB-5 is identified by NO and CO adsorption.•Unique adsorption behaviors of NO and CO were observed from in situ FTIR spectra.•The adsorption is promoted by temperature rise which produces more active sites.•The adsorption of NO and CO is competitive and adsorbed CO can be replaced by NO.

To develop new catalyst for controlling NO emission is important for pollution control. The investigation of NO or CO adsorption could contribute the fundamental understanding the reaction mechanism of de-NOx process and the coordinate state of the specific catalyst. Nanoporous nickel phosphate VSB-5 is an attractive catalyst and is firstly employed as the active component for the adsorption of NO and/or CO. In situ FT-IR and temperature programmed desorption (TPD) are used to characterize the adsorption behaviors. A large amount of NO and/or CO can be adsorbed in the pores of VSB-5 and strong bands from different adsorbed species are observed by in situ FT-IR investigation, which is confirmed by isotopic labeled adsorption. The amount of adsorption at room temperature unusually increases by raising the adsorption temperature to 100–200 °C. The possible reason may be explained by the generation of more active sites at elevated temperature which plays a more important role than corresponding desorption. The adsorption of CO and NO is competitive and the adsorbed CO may be replaced by NO due to a stronger bonding strength of the latter. This report contributes to monitor the active sites in the pores of VSB-5 and also makes VSB-5 to be an active candidate for NO or CO related catalytic process.

Graphical abstractLarge amounts of NO can be adsorbed on Ni2+ sites in the pores of VSB-5. The adsorption may be promoted by heating process helping NO to reach some inaccessible sites at lower temperatures, which demonstrates an unusual adsorption character.Figure optionsDownload full-size imageDownload high-quality image (151 K)Download as PowerPoint slide