| Research significance In virtue of the homogeneous molecular size pore structure and huge surface leading to selective adsorption, zeolite is widely used as adsorbent, catalyst and ion exchanging agent. Zeolite molecular sieves, due to their good thermal stability, chemical stability and biological stability, have been used in environment protection, biology engineering, petroleum chemistry, foodstuff, medication, agriculture, electronics industries and new materials fields. Microporous molecular sieves are important selective catalysts in petroleum and chemical industry. But their applications are limited because of small pore sizes, since big molecular are difficult to enter into the pores, at the same time big molecular produced in the pores are difficult to transgress, which results in side-reaction. Since Mobile Co. synthesized a series of mesoporous molecular sieves in 1992, the synthesis technology, properties testing and the study of crystallization mechanism have been the hot topic worldwide. However, because the pore sizes of mesoporous molecular sieves are simplex, their uses are impaired when dealing with complex gas group. As a result, the applications of mesoporous molecular sieves are limited. Moreover, the pore walls of mesoporous molecular sieves are thin, vulnerable to collapse at high temperatures. Obviously, the weak thermal stability also limits their wide application. Composite molecular sieves have mesoporous and micro-pore structures, and strong and week acid bit. This kind of structure can avoid the limitation of simplex pore structures, and has better adaptability when dealing with mixture of different molecular sizes, such as automobile gas, waste gas in factories. Because the mesoporous and micro-pore structures coexist in composite molecular sieves, and the pore walls become thick during the second crystallization, the thermal stability improves greatly. Also because the composite molecular sieves have multi-catalysis focuses, huge specific surface area, good thermal stability, they have potential applications in petroleum and chemical industry, environment protection and so on. Recently, the atom impurity adulterated mesoporous molecular sieves as catalysts have aroused extensive interests. Because the metal ions in them have high electric density, molecular sieves containing these metal ions have more acid bits and good catalyzing activity. Therefore, it is an important project to introduce transition metal ions and rare earth ions into molecular sieves. The molecular sieves with rare earth ions have high thermal stability and anti-vapor capability, so they are widely used in petroleum and chemical industry fields. At present, the impure atoms, such as aluminum,copper,tungsten, have been successfully introduced into the molecular sieves framework, and the molecular sieves show good catalyzing activities. It is ordinary for micro-pore molecular sieves to adulterate rare earth, but less ordinary for mesoporous molecular sieves, still less for the rare earth atoms to enter intomolecular sieves framework. Further, there are no reports of composite molecular sieves with rare earth element adulteration. Brief researches and conclusions 1. Meso-pore molecular sieves MCM-41 and microporous molecular sieves ZSM-3 were synthesized by controlling different temperatures. The results of XRD, IR and Raman spectra show that the samples are virtually mesoporous and micro-pore molecular sieves.2. By use of CTMAB and TMAOH as the templates, meso-microporous composite molecular sieves were hydro-thermally synthesized. The as-synthesized composite molecular sieves have diffraction peaks in small and large angle regions in their XRD patterns, corresponding to the mesoporous and micro-pore structures. The IR spectra show that the as-synthesized samples have characteristic absorption bonds of mesoporous MCM-41 and micro-pore ZSM-3 molecular sieves, and their IR spectra are clearly different from those of the mechanical mixtur...
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