Effect of the modified support γ-Al2O3-CaO on the structure and hydrodesulfurization activity of Mo and Ni-Mo catalysts

The effect of the support γ-Al2O3 modified with CaO by deposition–precipitation method on the structure, catalytic activity and selectivity of Mo and Ni-Mo catalysts for HDS was investigated. The resistance of the catalysts to deactivation by coke formation was also investigated. The samples have been characterized by means of XRD, DRS, XPS, Al27 NMR, TPR, and specific surface area and pore size distribution. The reaction of thiophene hydrodesulphurization, carried out at atmospheric pressure, was used as a model reaction for estimating the activity of the catalyst samples.The obtained results show that the applied method of modification with CaO leads to the formation of support with mesoporous structure and a considerable higher mechanical strength than that of the pure γ-Al2O3. Mo and Ni-Mo catalysts deposited on the modified support have higher HDS activity and resistance to coke formation. The presence of Ca2+ ions in the lattice of the support hinders the formation of crystallites of MoO3 and Al2(MoO4)3 phase. The higher catalytic activity of the samples with modified support is due to the higher degree of their sulfidation.

The effect of the support γ-Al2O3 modified with CaO by deposition–precipitation method on the structure, catalytic activity and resistance to coke formation of Mo and Ni-Mo catalysts for HDS was investigated. The synthesized catalysts deposited on the modified support have higher HDS activity and resistance to coke formation. This is as a result of the presence of Ca2+ ions which hinders the formation of MoO3 crystallites on the catalytic surface.Figure optionsDownload as PowerPoint slide