Cobalt and nitrogen co-doped hollow periodic mesoporous organosilica spheres activated by potassium chloride for selective oxidation of ethylbenzene

/HPMOs-KCl was attributed to the activation of KCl, which increased the specific surface area of the catalyst and thus facilitated the exposure of more metal active sites. After the removal of unstable metal species through further acid treatment, the remaining metal active sites were thus fully exposed and stably embedded in the framework of the hollow periodic mesoporous organosilica spheres (HMPOs). This work presents an efficient catalyst and offers new insights for the improvement of heterogeneous catalysts.