Propylene oxide is an important chemical raw material. In this paper,
Density Functional Theory (DFT) was used to calculate the epoxidation of
propylene on the dimer MoOx by Gaussian 09 software. Firstly, we
established the structure of the dimer MoOx/SiO2 and analyzed it, and
then calculated the dehydrogenation process of propylene and the
formation process of PO. It was found that the activity of O in Mo-O-Si
was higher, which was beneficial to the AHS process of C3H6, but the
reaction activity of different O substances to the formation of PO was
very low. In order to solve this problem, we established a dimer MoOx
model with defect sites, and found that the defect sites in the dimer
could effectively activate O2 (O2- 2), and the activated material O had
high PO selectivity. Compared with process of AHS and the process of PO
formation, the energy barrier of PO formation path was very low, which
was the main product. At the same time, we also established the MoOx
model of Fe doped dimer and the MoOx model of Fe doped defect dimer. It
was found that the MoOx clusters were more active due to Fe doping, and
the energy barriers of both AHS process and PO formation path were
greatly reduced compared with those before doping. The presence of Fe
made it easier for the dimer MoOx to form defect sites, which made it
easier to activate O2 (O- 2) and reduced the energy barriers of both AHS
and PO formation processes.
A DFT study of epoxidation of propylene on dimer MoO(x)