The stability and catalytic performance of K-modified molybdena supported on a titanate nanostructured catalyst in the oxidative dehydrogenation of propane

Abstract

Titanate nanotube supported molybdena was evaluated as a catalyst in the oxidative dehydrogenation of propane to propylene. The synthesized titanate nanotubes with high specific surface area were prepared by a hydrothermal method. The characterization of pristine nanotubes was performed via XRD, Raman, SEM, TEM and BET. The presence of hydrogen titanate nanostructure was confirmed in the bare support. Incipient wetness impregnation method was used to prepare MoTNT-x (x = 5, 10, and 15 wt% molybdena). The as-prepared catalysts' characterization was investigated using Raman, XRD, SEM, EDS, TEM, BET, TGA, and CHNS. Furthermore, H₂-TPR was performed to explore reducibility of the catalysts. XRD and Raman results indicated development of the anatase phase in MoTNT-x catalysts upon calcination, along with specific surface area loss according to BET. Study of the catalytic performance of the samples showed an increase in catalytic activity and a significant drop in propylene selectivity with rising molybdena content. The maximum yield of propylene (about 9.3%) was obtained in 10 wt% of Mo content. The effect of potassium loading as a promoter in K/MoTNT-10 catalyst was also explored through characterization of the surface molybdena species and catalytic performance. Due to the presence of potassium, propylene yield increased from 9.3% to 11.3% at 500 °C. The stabilities of both catalysts were considered for 3000 min and showed only slight drops in propane conversion and propylene selectivity.