Study On The Catalytic Oxidation Of HCHO Over Co₃O₄ Catalysts

Catalytic oxidation is considered as the most promising technology for HCHO abatement due to its lower reaction temperature and zero secondary pollution.In this research,the effect of various treatment atmosphere on HCHO catalytic oxidation of Co3O4 catalyst has been investigated,it was found that treatment atmosphere has a significant influence on the catalytic performance,and the relationship between the structure of catalyst and the adsorption and activation of HCHO has been revealed by using DFT calculation.Inert gas treatment exhibited a significant promotion effect on the activity of Co3O4 catalysts.100%conversion of HCHO was achieved at 120? over Co3O4 catalysts treated with N2 atmosphere.Meanwhile,the effect of N2 treatment temperature has also been studied,When the temperature increased from 200? to 300?,the completely conversion temperature of HCHO was shifted from 150? to 130?.Further increased the treatment temperature beyond 300?,the improvement of catalytic activity was not evident.From XRD and TEM results,we observed that the gas treatment has no fluence on the phase of Co3O4 except H2 treatment.However,the Co3O4 morphology changed from nanoparticles to the coexistence of nanorods and nanoparticles after N2 treatment.The change of Co3O4 catalysts morphology may lead to the different exposed crystal planes,which has a significant influence on the active sites and the adsorption of HCHO.Therefore,the interaction of HCHO molecules with the different Co3O4 surface(including {110},{100}and {111} facets)was investigated by using DFT calculation.It was found that the {110} facet was mainly composed of Co3+ sites and the other two planes contained more Co2+.The order of adsorption energy of HCHO on different Co3O4 surfaces were as follows:{100}>{110}>{111}.The simulation results showed that after a surface oxygen atom was removed from the Co3O4 surface to form defective structure.The adsorption energy of HCHO molecules on defective surfaces was larger than perfect surfaces.Consequently,the formation of oxygen vacancy contributes to the adsorption and activation of HCHO.The activity enhancement of the Co3O4 catalysts due to the treatment in inert gases may lead to more oxygen vacancies formed,which contributes to the catalytic oxidation of HCHO.