From Ionothermal Method To Solvent-free Method-Synthesis Of Aluminophosphate Molecular Sieve

Molecular sieve is widely used in adsorption, catalysis and ion exchange, because of its hierarchically porous structure and high specific area. Aluminophosphate molecular sieve as is a prominent one among the aluminophosphate molecular sieve family, which have received mu ch attention in its synthesis, characterization and catalytic performance. Compared with hydrothermal/solvothermal and ionothermal, solvent-free is a new method without solvent participates in the reaction system. This method exhibits many advantages, such as high synthesis yield, low waste production, energy and cost saving, which can provide a green and sustainable development approach for prepared zeolite. In this paper, aluminophosphate molecular sieve with a variety of topologies has been synthesized by the ionothermal and solvent-free. The main research contents are as follows:Al PO4-5 aluminophosphate molecular sieve with AFI topology has been synthesized by microwave irradiation under solvent-free conditions. The key influential factors controlling the crystallization of AFI structure, such as, P2O5/Al₂O₃, C/Al₂O₃, TEABr（tetraethylammonium bromide） /Al₂O₃, HF/Al₂O₃ and H2O/Al₂O₃ molar ratio, aluminum source, the reaction temperature and time, and milling, were thoroughly investigated. The results reveal that the optimum synthetic conditions of this material are as follows: the initial composition is 1.0Al₂O₃: 3.0P2O5: 2.0HF: 8.0TEABr: 125 C, aluminum isopropoxide is the best aluminum source, the best temperature and time is 180℃ and 2h, respectively. Activated carbon needs to be pretreated before used as the reaction medium. The resultant Al PO4-5 molecular sieves were characterized by XRD, SEM, TEM, N2 physisorption. The results obtained show that the samples were composed of nanoparticles and typical hexagonal, and exhibit hierarchically porous characteristic under solvent-free conditions.The highly efficient synthesis of an LTA-type aluminophosphate molecular sieve by an improved ionothermal method from a gel containing low-dosage ionic liquids. The influence of HF/Al₂O₃, Morp/Al₂O₃ and ILs/Al₂O₃ molar ratio, reaction temperature and time on the LTA zeolite synthesis has been investigated in detail, and the synthesis conditions were optimized. The resultant LTA molecular sieves were characterized by XRD, SEM, TG-DTA, CHN elemental analysis, solution 13 C NMR, EDX, TEM and N2 physisorption. The composition of the resulting LTA-type molecular sieves are determined to be（Al12P12O48）（C4H9NO） 2（C8H15N2+） 2（F-） 2, for which morpholine together with 1-butyl-3-methylimidazolium cations act as the structure-directing agent. The high zeolite yield, as well as the high specific surface area and micropore volume of the calcined LTA-type materials.Finally, Triclinic Al PO4-34 with CHA topology has been successfully synthesized under seed-assisted, solvent-free conditions. Obtained the triclinic CHA aluminum phosphate molecular sieve with the high purity by controlling the reaction temperature and time, and the seed amount. The resultant CHA molecular sieves were characterized by PXRD, SEM, TG-DTA, CHN element analysis, liquid 13 C NMR and N2 physisorption. The results indicate that the CHA molecular sieve has the composition（Al6P6O24）（C4H9NO）2, for which morpholine acts as the structure-directing agent. The high surface area and micropore volume of the calcined CHA material.