Aromatics Hydrogenation Saturation And Naphthene Ring Opening In Diesel

Palladium-platinum catalysts supported on a mesoporous material containing secondary structural units of zeolite Y (Y-MCM-41) and a micro-mesoporous material composed of zeolite Y overgrown with a thin layer of MCM-41(MCM-41/Y) were prepared by an ion exchange method. Its hydrogenation activity in aromatics saturation and ring opening activity were investigated. Aromatics hydrogenation and ring opening reaction was an effective way to enhance the cetane numbers of diesel.In chapter 2, it proves that the introduction of the secondary structural units of zeolite Y into the wall of MCM-41 results in a stronger acidity strength and a higher hydrothermal stability. Y-MCM-41 with different ratio of Si/Al was prepared and the synthesis condition of the Y structural units was reviewed. The catalysts were characterized by temperature programmed reduction, temperature programmed desorption of NH3 and atomic absorption spectroscopy. The effect of ion exchange method on activity of tetralin hydrogenation was examined. It was found that the ion exchange method exerted a profound effect on the final metal content, interaction between metal and support, and the activity. For the catalysts with a moderate metal-acid balance, a higher amount of acid sites was helpful for the hydrogenation activity.In chapter 3, Y, MCM-41/Y, MCM-41+Y and MCM-41 supported Pd-Pt catalysts were prepared by the ion exchange methods. The effect of acidity, metal and size of pores on the ring opening of decalin was studied and a possible reaction scheme on bifunctional catalysts was proposed. It was found that a suitable acidity strength and amount of acid sites were helpful for the activity and selectivity of ring opening of decalin. The interaction between Pd-Pt and acid sites of supports enhance the activity of catalysts. Isomerization on acid sites and hydrogenolysis on metal both improved ring opening reaction activity. Stereoisomerization and skeletal isomerization of decalin affected ring opening reaction on different aspects.