Controllable preparation of ultrafine Co3O4 nanoparticles on H-ZSM-5 with superior catalytic performance in lean methane combustion

Abstract

Co3O4/HZSM-5 has been proven a competitive catalyst in lean methane combustion. However, the poor dispersion of Co3O4 hinders its industrial application. To prevent the agglomerate of Co3O4 nanoparticles over zeolite, polyvinyl alcohol (PVA) assisted impregnation method is proposed to prepared Co3O4/H-ZSM-5 catalysts. It is found that the crosslink structure of PVA limits the free movement of Co2+ ions, by which Co3O4 nanoparticles are effectively dispersed on the surface of H-ZSM-5 and thus ultra-fine Co3O4 nanoparticles are obtained. The obtained catalysts exhibit stronger interaction between Co3O4 nanoparticles and H-ZSM-5 support, higher ratio of surface Co3+, which enhance the catalytic activity. Experiments show when the mass ratio of PVA to Co is 1.0, the temperature at methane conversion of 90 % (T90) is 391 °C, while T90 is 460 °C with the catalyst prepared by traditional impregnation method. Moreover, the catalyst shows a lower activation energy and much higher thermal stability.