CoMn2O4 supported on carbon nanotubes for effective low-temperature HCHO removal

Formaldehyde (HCHO) is harmful to environment and human health, even at extremely low concentrations. Catalytic oxidation on metal oxides is an effective method for HCHO removal. Transition metal oxides have attracted much attention due to its advantages of low cost and good redox properties, but it requires the high reaction temperature and energy consumption to reach the good catalytic activity for HCHO removal. In this work, Mn-Co mixed oxides supported on carbon nanotubes (CNTs) were prepared for enhancing the low-temperature catalytic activity of HCHO removal. The results of XRD, TEM and XPS characterization confirmed the formation of CoMn2O4 solid solution on CNTs. The highest relative content of Co3+, Mn3+ and active lattice oxygen were achieved at the optimal composition of 3Mn-1Co. The HCHO oxidation test showed that CoMn2O4/CNTs (3Mn-1Co) had the best catalytic activity at 160 °C, obtaining 95% HCHO (100 ppm) removal efficiency and 95% CO2 selectivity at GHSV = 30,000 mL gcat-1 h-1. Compared with the similar catalysts previously reported in literatures, CoMn2O4/CNTs was of the lower T90 value for HCHO oxidation. [Display omitted] •Mn/Co molar ratio of 3:1 was prone to form CoMn2O4 solid solution on CNTs.•The formation of active lattice oxygen on CoMn2O4 was beneficial to HCHO oxidation.•The combination of CNTs and Co-Mn oxides solid solution is promising to prepare catalysts for HCHO removal.