K-modified Sn-containing dendritic mesoporous silica nanoparticles with tunable size and SnOx-silica interaction for the dehydrogenation of propane to propylene

Sn-containing dendritic mesoporous silica nanoparticles (Sn-DMSNs) were successfully prepared by the in-situ co-assembly method. Sn-DMSNs preserve original structural characteristics with three-dimensional and center-radial pore structure. The nanoparticle sizes of Sn-DMSNs can be controlled systematically from 170 nm to 360 nm depending on the molar ratio of NaSal/CTAB. Sn species are incorporated into the matrix of silica and the highly dispersed SnO x species are achieved. Sn-DMSNs catalysts exhibit excellent catalytic performance and stability in the propane dehydrogenation. The highly dispersed SnO x species rather than polymeric SnO x or crystalline SnO 2 species contribute to the activation of propane and formation of propylene. The molar ratio of NaSal/CTAB also shows an important role in the structure of support and SnO x species. The excellent stability of Sn-DMSNs catalysts can be ascribed to the good ability to restrain coke formation and strong interaction between SnO x species and silica. The effect of potassium on Sn-DMSNs catalyst is also investigated.