Mesoporous single-crystal Cr2O3 : Synthesis, characterization, and its activity in toluene removal

In this paper, a series of ordered mesoporous single-crystal Cr2O3 samples were synthesized through a hard-templating pathway by using three-dimensional (3D) cubic mesoporous silica, KIT-6, as the template and chromium nitrate as the precursor. In the synthesis, the intermediate composites (chromium nitrate/KIT-6) were calcined in air for 4 h at different temperatures (from 400 to 700 deg C, interval 100 deg C) to decompose the nitrate species. Then, the silica template was removed by dissolution in 10% HF solution twice. The resulting Cr2O3 samples were characterized by XRD, TEM, XPS, and N2-sorption analysis and their catalytic properties were also investigated in the oxidation of toluene. These results showed that the obtained ordered mesoporous Cr2O3 are exact reverse-replica of the template. It was also found that the catalytic activity was related to mesostructure and/or surface area as well as the calcination temperatures.