With The Pore Structure Of Mesoporous Carbon, Silica And Zeolite Molecular Sieve Materials Prepared

Hierarchically porous structures in nature such as stems of plant,bones of animals etc.play important roles in mass transfer for the metabolism.Materials with hierarchical pore structures can also minimize the channel blockings for fast diffusion of bulky molecules in the industrial catalyst,adsorption,separation and waste-disposing etc,because they can effectively access the mesopores and/or micropores interconnected by macroporous system.Mesoporous silicate with crystallized pore wall can meet the industrial requirements of acidity,diffusion, thermal stability and hydrothermal stability.As to preparation of hierarchical porous materials through combining soft and hard template,it is an economic pathway for industrial production of hierarchically porous materials to select a commercially available hard template.In the thesis,the polyurethane(PU) foam is selected as a macrostructure scaffold,soluble phenolic resin with low molecular-weight as a carbon precursor,hierarchically porous monoliths with ordered meso-structure is synthesized.Zeolites with uniform mesopores are also prepared using the carbon-containing monolith as a hard template through vapor-assisting transformation method.Two parts are included in the thesis.The first one focused on the hierarchically porous monoliths,including silica,polymer,carbon,polymer-silica and carbon-silica composite,with ordered meso-structure are prepared through evaporation induced self-assembly on the polyurethane(PU) foam scaffold.The second one covered the preparation of molecular sieves with uniform mesopore size by the carbon-containing materials mentioned in the first part as hard templates via vapor assisting transformation method.In chapter two,hierarchically porous silica monoliths have been fabricated through inorganic-organic cooperative assembly on the commercially macro-structural scaffold.Hierarchically porous silica monoliths with 2-D hexagonal (p6mm) meso-structure were prepared through evaporation induced self-assembly on the 3-D interconnecting struts of polyurethane(PU) foam scaffold.The preparation is carried out in acidic solution via using the organic silica as a precursor,copolymer P123 as a template for the meso-structure and PU foam as a macrostructure scaffold. Hierarchically porous silica monoliths are prepared through surface templating and volume templating method followed by different post-treatment,respectively. Hydrothermal treatment enhanced their surface area and pore size etc..they can effectively remove the Microcystin-LR in water.In chapter three,a simple strategy for the synthesis of macro-mesoporous carbonaceous monolith materials has been demonstrated through an organic-organic self-assembly on the interface of an organic scaffold such as polyurethane(PU) foam. Hierarchically porous carbonaceous monoliths with cubic(Im(?)m) or hexagonal (p6mm) meso-structure were prepared through evaporation induced self-assembly of the meso-structure on the 3-D interconnecting struts of the PU foam scaffold.The preparation was carried out by using phenol/formaldehyde resol resin as a carbon precursor,tri-block copolymer F127 as a template for the meso-structure and PU foam as a sacrificial monolithic scaffold.Their hierarchical pore system was macroscopically fabricated with cable-like meso-structured carbonaceous struts.The carbonaceous monoliths exhibit macropores of diameter 100-450μm,adjustable uniform mesopores(3.8-7.5 nm),high surface areas(200-870 m²/g) and large pore volumes(0.17-0.58) cm³/g.Compared with the corresponding evaporation induced self-assembly(EISA) process on a planar substrate,this facile process is a time-saving,labor-saving,space-saving and highly efficient pathway for mass production of ordered mesoporous materials.In chapter four,a facile approach of solvent evaporation induced coating and self-assembly has been demonstrated for mass preparation of ordered mesoporous carbon-silica composite monoliths by using a polyether polyurethane(PU) foam as a sacrificial scaffold.The preparation was carried out by using resols as a carbon precursor,TEOS as a silica source and tri-block copolymer Pluronic F127 as a template.The PU foam with macrostructure can provide a large plenty of tri-dimensional interconnecting interface for evaporation induced coating of the phenolic resin/silica-block copolymer composites and self-assembly of the meso-structure,and endows composite monoliths with a diversity of macroporous architectures.SAXS,XRD and TEM results indicate that the obtained composite monoliths have ordered meso-structure with two-dimensional(2-D) hexagonal symmetry(p6mm) and good thermal stability.By simply changing the mass ratio of resol to TEOS in a wide range(10～90%),a series of ordered mesoporous composite foams with different composition can be obtained.The composite monoliths with hierarchical macro/mesopores exhibit large pore volumes(0.26-0.77 cm³g^-1), uniform pore sizes(4.2-9.0 nm),and surface areas(230-610 m²g^-1).A formation process of the hierarchically porous composite monoliths on the struts of the PU foam through the evaporation induced coating and self-assembly method is illuminated in detail.The simple strategy performed on the commercial PU foam is a good candidate for mass production of interface assembly materials.In chapter five,Silicalite-1 molecular sieve with uniform mesopore including MZ-1,MZ-2,MZ-3 were prepared by nanocasting ordered mesoporous carbon or carbon-silica composite and using TEOS as a silica source.The preparation was carried out under vapor assistant hydrothermal condition within the nanochannels of 2-D hexagonal mesoporous templates.The results show that MZ-1 is prepared through ordered mesoporous carbon template combining nanocasting method and is composed of stacking zeolite nanoparticles,the intercrsystal pores with about 4 nm in diameter are built up basing on the uniform particles.Combining the composite template and nanocasting strategy,molecular sieve MZ-2 is also obtained through vapor assisting transformation.MZ-2 is consisted of interconnected zeolite nanoparticles with uniform intercrystal pores.The silica in the pore wall of composite template effectively linked the particles formed in the mesochannels.By directly transforming the carbon-silica composite with the aid of the vapor,molecular sieve MZ-3 with mesopores is also successfully fabricated by simply impregnating the soft structure-directing agents.