Design order macro-meso porous structure monolithic Co3O4/SiO2 catalyst via a novel 3D printing for the highly efficient catalytic combustion of toluene

The shortcomings of Co-based powder catalysts such as amorphous susceptibility to loss and high influence by pressure drop have become the key factors affecting their catalytic activity. In this paper, two methods were proposed to prepare novel monolithic Co3O4/SiO2 catalysts by 3D direct ink writing (DIW) technology: (1) one-step method of printing the active component with supports, (2) two-step method of printing the support first, and then loading the active components. The results showed that the monolithic catalyst prepared by the two-step method possessed more abundant Co3+ and lattice oxygen (Olatt) species than the one-step method, which jointly promoted the catalytic conversion of toluene. However, the catalyst printed by the one-step method had a stronger interaction between the active component and the support, showing better thermal stability and water resistance. In addition, the SiO2 support (the calcined product after SiO2 ink printing) enhances the activity, stability, compression resistance, while the N–SiO2 support (the calcined product after SiO2 precursor ink printing) can effectively prevent blockage of the pore structure by the binder and increase physical properties such as pore volume and specific surface area of Co3O4/SiO2 catalyst.