Investigation On Novel Materials As The Supports Of Diesel Aromatics Saturation Catalysts

Palladium-platinum on novel mesoporous or micro-mesoporous materials was prepared by ion exchange method. Its hydrogenation activity in aromatics saturation was investigated in the absence and presence of DMDBT or thiophene.In chapter 2, hydrothermally stable mesoporous aluminosilicates with tubular morphology and hexagonal nanochannels were prepared through co-assembly of Bata alumninosilicate precursors. The XRD results indicated that the synthesized materials were well-ordered hexagonal mesostructures of MCM-41. The highly regular hexagonal mesostructures could survive 150 h aged in 120 oC water, exhibiting good hydrothermal stability. Combining the SEM and TEM investigation, the as-made materials showed tubular morphology with diameter of 0.4μm. Acidity and pore structure are characterized by N2 adsorption-desorption isotherms, IR and NH3-TPD. It is explain the reason that good hydrothermal stability by MAS NMR and N2 adsorption-desorption isotherms. The Pd/HMSUB-41 catalyst has high activity and good sulfur tolerance towards hydrogenation of aromatics of smaller diameter, and has an enhanced ability for pyrene hydrogenation.In chapter 3, a synthesis route for the preparation of MCM-41 with secondary building units of Y zeolite has been developed. It was overcomed some difficults about great expense of template, SiO2/Al2O3 ratios in a narrow range and long crystallization time. The material was characterized by XRD, IR, MAS NMR, SEM, NH3-TPD and N2 adsorption-desorption isotherms. The results indicate that the material has well-ordered hexagonal structure, with a thicker wall than that of the MCM-41 synthesized by a direct hydrothermal route. The MSUY-41 has a uniform mesoporous diameter of 3.0 nm and pore wall thickness of 1.86 nm. SEM images show a very uniform net-like morphology, which is different from the loose appearance of the direct sample from the direct route. Furthermore, it has a stronger acid strength and a higher hydrothermal stability. The MSUY-41 sample retains a well-ordered hexagonal structure upon streaming at 750 oC for 2 h. The acid strength of HMSUY-41 material is higher than that of HMCM-41 material, and lower than that of HY material. The sample was used as the support of a Pd-Pt catalyst for the polyaromatics hydrogenation.The sulfur tolerance and the activity of the catalyst was found to be superior to that prepared with the normal MCM-41 as support. The enhancing effect is...