Effect of A2+ and B3+ substitution for Cobalt on low-temperature catalytic removal of formaldehyde over spinel AxB3-xO4 (A= Mg, Ni, Zn; B= Cr, Fe, Al)

Abstract

Abstract Spinel Co3O4 catalysts were modified by A2+ (A\u202f=\u202fMg, Ni, Zn) and B3+ (B\u202f=\u202fCr, Fe, Al) metal cation substitution respectively for low-temperature removal of formaldehyde. Among of those A2+ substituted catalysts, Ni0.8Co2.2O4 was found to be the best low-temperature catalytic activity with T100 of 90\u202f°C and 100% CO2 selectivity. However, B3+ substitution was found negative to improve the low-temperature catalytic performance for relatively weaker oxidation capacity of Cr3+, Fe3+ and Al3+. Results of XRD and Raman characterization confirmed that both A2+ or B3+ cations substitution caused structural and surface electronic variation, and NiCo2O4 had been successfully synthesized. XPS analysis revealed that surface hydroxyl coming from Ni(OH)2 was enriched by Ni2+ substitution. The active oxidant Co3+ and abundant hydroxyl were concluded to dominate the low-temperature activity of NixCo3-x catalysts.