Infiluence Of Carrier Modification On Hydrodesulfurization And Hydroring Opening Performance Of Noble Metal Catalyst

In this paper,a series of Pd-loaded catalysts were prepared using activated carbon and mesoporous molecular sieves as carriers.By modulating the acid-base properties of the carriers and the spatial distribution of the noble metals on the carriers,the effect of the carrier properties on the performance of the series of noble metal catalysts for hydrodesulfurization（HDS）and ring opening reaction of decahydronap Hthalene was investigated using dibenzothiop Hene（DBT）as a model compound for HDS and decahydronap Hthalene as a model compound for OR.（1）Studies on activated carbon carriers have shown that modification of activated carbon with nitric acid（H-C）or H-C with NaOH and KOH reduces the specific surface area but increases the dispersion and H₂ adsorption and correlates with the HDS activity of the catalyst.It was also shown experimentally that the low temperature peak correlates with the basicity of the carrier,while the high temperature peak can be attributed to the adsorption of H₂ on the metal;the higher the H₂ adsorption,the higher the activity.In addition,the DDS reaction pathway is likely to be related to the hydrogen species adsorbed at low temperatures or to those adsorbed on a basic（2）Pd/MCM-41 and Pd/Si-MCM-41 catalysts were prepared by an isovolume impregnation method.The performance and kinetics of the hydrodesulfurization（HDS）reaction of the two were investigated.The results showed that in the Pd/MCM-41 catalyst,Pd was mainly filled in the mesoporous pores of MCM-41,whereas in the Pd/Si-MCM-41catalyst,Pd was mainly distributed on the MCM-41 surface.the HDS activity and direct desulp Hurisation path selectivity of Pd/Si-MCM-41 were higher than those of Pd/MCM-41.the Pd/Si-MCM-41 catalyzed DBT HDS reaction can be described by pseudo primary reaction kinetics.In contrast,the DBT HDS reaction on Pd/MCM-41 follows the L-H kinetic model.（3）Pd/Mβcatalysts were prepared using the conventional impregnation method,with Pd particles filled in the mesopores of the MCM-41 p Hase of Mβ;Pd/S-Mβcatalysts were prepared by loading a toluene solution of Pd（OAc）₂ onto a pre-silylated Mβcarrier.On the Pd/S-Mβcatalyst,noble metal particles were distributed on the outer surface of MCM-41 to achieve spatial separation of the metal particles from the acidic H-β.In the ring opening of nap Hthanes and the hydrodesulp Hurisation of dibenzothiop Henes,the Pd/Mβbehaves similarly to a normal bifunctional catalyst.Although Pd/S-Mβand Pd/Mβhave almost the same acidity,it is the spatial separation of the non-acidic MCM-41 relative metal and acid sites in Pd/S-Mβthat leads to an almost complete loss of acid functionality.