The Construction And Research Of Novel Nano Catalyst Material Between The Montmorillonite Layers

Porous zeolite supported metal catalyst has been the focus of attention since it was invented, playing a pretty important role in the petrochemical catalytic reaction. Fortunately, novel nanotechnologies have been developed in recent years to synthesize complex solids with well-defined characteristics, accelerating the development of the porous zeolite supported metal catalyst, and those have already found applications in catalysis. The researches of the catalysts are focus on the regulation of the porous structure of zeolite for preparing hierarchical porous supports, the improvement of the acidity of zeolite for better catalytic reactivity and the construction of different sizes and shapes of metal nanoparticles, et al. The research of this paper is focus on the construction of hierarchical porous zeolite and different sizes and shapes of metal nanoparticles between the innerlayers of montmorillonite, respectively, by using the feature of the natural layered structure and the isolation effect of the montmorillonite. And finally, the novel nanostructure catalysts with high activity, well stability and good product selectivity were composed. The results of this research are as following:1. The hierarchical porous structure was constructed by synthesizing nano zeolite crystal between the lamellae of montmorillonite. The montmorillonite-interlamination-microreactor has been constructed by exchanging different length of carbon chain of pre-pillar agents ?Cetyhrimethyl ammonium bromide, dodecyltrimethyl ammonium bromide and octadecyltrimethyl ammonium bromide? and silicon source into the lamellae of montmorillonite. The effect of the pre-pillar agents is to enlarge the interlayer spacing of the montmorillonite. And it was found that nano-zeolite can be synthesized between the lamellae of montmorillonite with the inducing effect of montmorillonite but without any template of zeolite. The micro-mesoporous structure was constructed possessing both uniform micropores ?-0.50 nm? within the nano-zeolite pillars and mesopores ?-3.90 nm? between the nano-zeolite pillars in the interlamellar galleries of montmorillonite clay. Further,6wt.% of Ni was loaded on the hierarchical porous material preparing catalyst for the catalytic reaction of hydrocracking of residual oil. The results show that the hierarchical porous catalysts possess better conversion and product selectivity than traditional single channel catalysts did. Furthermore, Ni/1631-MMT exhibited the best conversion of residual oil ?76.6%? and highest selectivity of gasoline ?71.2%?, for the reason that the BET surface area of this catalyst is the high (290 m²g^-1) and the porous structure is neat with the total pore volunm of 0.76 cm³g^-1, most importantly, the size of the Ni particles is small ?11.8nm on average?, which are dispersed evenly in the support.2. A MFI zeolite nanosheet-pillared montmorillonite clay ?MPC? hierarchical material has been synthesized under hydrothermal conditions through recrystallization method. Because of the isolation effect of the montmorillonite layers, the nano zeolite particles are prevented fromed reunion. The N2 adsorption-desorption test indicates that the BET surface area of the material is very high, up to 734 m²g^-1, and the total pore volumn is 1.21 cm³ g^-1, possessing uniform micropores in the crystalline zeolite pillars and uniform mesopores between the zeolite pillars in the montmorillonite interlayer galleries. NH₃-TPD test indicates that the acidity of the catalyst was pretty strong. The total acidity of this hierarchical porous material was 1.34 mmol g^-1, including 0.94 mmol g^-1 of strong acidity. Further,6wt.% of Ni was loaded on the hierarchical porous material preparing catalyst for hydrocracking of residual oil. It was found that as the BET surface area and the pore volume of the catalyst enlarge, the conversion of residual oil and selectivity of gasoline become higher. The sample which was recrystallizated by 5d showed the best catalytic performance of the hydrocracking of residual oil, with the highest conversion of residual oil of 81.2%, and the best selectivity of gasoline of 75.8%. The hierarchical porous catalysts prepared by the recrystallization method have the bigger pore volumn and higher BET surface area than the catalysts that were synthesized by the inducing method, resulting in the better catalytic performance of hydrocracking on residual oil.3. The sizes and shapes of metal nanoparticles were constructed by using the layer structure and the isolation effect of the montmorillonite layers. A series of highly dispersed nickel nanoparticles supported by silica pillared clay ?Ni0-SPC? have been synthesized with a facile instu-reduction process. The results suggest that the materials possess highly ordered mesoporous structure and the highly dispersed nickel nanoparticles with a uniform size about 4.7 nm in an ordered configuration in the silica pillared clay's pores. The FTIR and XPS test results indicate that the nickel particles were ordered encapsulated into the frameworks of the pillared clay in the Ni0-SPC samples, resulting in the stronger interaction between the nickel particles and the pillared clay support. Meanwhile, with the nickel content increasing, the pore size, pore volume and the surface area are increasing. Moreover, the nickel catalysts exhibited higher catalytic performance on the hydrodechlorination of chlorobenzene than the traditional catalysts did which was synthesized by the impreganation-reduction method. As the nickel content of the catalysts increased from 2wt.%to 6wt.%, the conversion of chlorobenzene increased, about 97.8% at 6wt.% Ni-content, and good reusability. The conversion of chlorobenzene was still 94.1% when the catalyst was used in the fifth time.4. Highly dispersed of Pt nanoparticle catalyst was prepared by sol-fixed-reduction method, which with the average Pt particle size of 3.76nm. The Pt nanoparticles were closely associated with the distribution of silica pillars of pillared montmorillonite clay. The Pt nanoparticles mainly appear ellipsoidal in shape with a small size. Besides, XPS and CO-IR results indicated that dueing to the electronic absorption effect of the support, the electron cloud outside the Pt metal was reduced, leading to the improvement of the hydrogenation property of Pt catalysts. The catalytic performance of Pt catalyst was tested by hydrogenation of naphthalene, exhibiting a good conversion of naphthalene. When the catalyst with 1.5wt.% content of Pt was used, the conversion of naphthalene was up to 90.1% and the selectivity of trans-decalin was high under the reaction temperature of 200? and the hydrogen pressure of 6MPa. The ratio of trans-decalin to cis-decalin was up to 2.41.