Influence of the Silicon Deposition on the Industrial Silicon Trapping Catalyst

Abstract

The structure and surface properties of the industrial silicon trapping catalysts were characterized by XRF, XPS, XRD, NH₃-TPD and NMR. The silicon trapping mechanism of the industrial silicon trapping catalyst was discussed. The results showed that the silicon capacity reached 28.17% during this lifetime. The captured silicon mainly existed on the surface of the silicon trapping catalyst as amorphous silicon with abundant Q species including Si(OSi)₄, Si(OSi)₃(OX), Si(OSi)₂(OX)₂, and Si(OSi)(OX)₃, proving the silicon was caputured as the amorphous silicon bilayer deposition model. After silicon deposition, the pore properties of the silicon trapping catalyst changed greatly. Compared with the fresh catalyst, the specific surface area and pore volume of the spent industrial silicon trapping catalyst decreased by 49.17% and 22.92% respectively. The deposition of silicon leaded to the loss of acid sites and changed the interaction between the support and the active metal, which result in the reduction of the number of active metal species. This may explain how the deposited silicon is related to the deactivation of the hydrotreating catalysts.