Preparation of mesoporous silica supported Nb catalysts and in-situ XAFS characterization during carburization process

Mesoporous silica supported Nb catalyst (imp Nb/SBA-3) was prepared by impregnation of NbCl5 to the SBA-3 support. The mesoporous silicate-wall incorporated Nb catalyst (inc Nb-SBA-3) was synthesized by introducing NbCl5 into an SBA-3 precursor solution. Both catalysts were carburized by a temperature programmed reaction (TPR) method under CH4/H2 gas stream. Nb K-edge in-situ XAFS analysis revealed that Nb2O5 was reduced to NbO2 in the first stage of TPR and converted into NbC in the second stage. The silica-wall incorporated Nb species were highly dispersed and hardly reduced nor fully carburized. The difference in the carburization process between imp Nb/SBA-3 and inc Nb-SBA-3 was clarified.