2015 Volume 58 Issue 5 Pages 312-320
The effects of zeolite structure on rhodium phosphide (Rh2P) formation, dispersion and hydrodesulfurization (HDS) activity were investigated. TPR showed that the order of maximum peak temperature for phosphates reduction was Na-beta>NaMFI>NaMOR. The XRD patterns of reduced catalysts revealed that the order of Rh2P formation temperature agreed with that of phosphate reducibility. CO uptake of NaMOR-supported catalyst was much lower than those of other zeolite-supported catalysts. These results suggested that since the NaMOR support had a one-dimensional channel, the phosphates and Rh species did not easily diffuse into the micropores. The order of thiophene HDS conversion was NaMFI>Na-beta>>NaMOR. The order of average particle size of Rh2P calculated from TEM images was NaMOR>Na-beta ≈ NaMFI. Since formation of Rh2P on the Na-beta needed high reduction temperature, the beta structure might be partially collapsed. Well-dispersed Rh2P was formed on NaMFI at lower reduction temperature, so that this catalyst exhibited the highest HDS activity among the zeolite-supported catalysts.
