Solvent-free(low-volume) Synthesis Of Aluminosilicate And Aluminophosphate Zeolite Materials

Zeolite is a typical crystalline microporous material.Due to its uniform channels and high hydrothermal stability,it has been widely used in catalysis,adsorption separation,ion exchangers and many other emerging fields.Compared with traditional hydrothermal/solvothermal synthesis of zeolite,the ionothermal and solvent-free synthesis of molecular sieve have many advantages.Avoiding the presence of solvents in the synthesis,not only reduces the generation of waste,but also improves the yield of zeolite products.In addition,it not only reduces the loss of raw materials,but also improves the synthesis efficiency and reducing the use of raw materials,energy and costs.In this paper,based on ionthermal method and solvent-free method,three kinds of molecular sieves with MFI-type,CHA-type and ERI/CHA-type were synthesized.The main research contents are as follows:1.The HZSM-5 aluminosilicate zeolite molecular sieve were synthesized using 1-ethyl-3-methylimidazolium bromide as solvent and structure-directing agent under generalized ionothermal reaction system by interzeolite transformation from zeolite HY.The effects of HY/Si O₂ ratio,NH₄F content,TPABr content,crystallization temperature and crystallization time on the crystalline phase of HZSM-5aluminosilicate zeolite molecular sieve were discussed in detail.The product HZSM-5aluminosilicate zeolite molecular sieve with MFI-type was characterized by XRD,SEM,EDX,N₂ physical adsorption and desorption.According to the results,the HZSM-5 zeolite materials were directly synthesized by interzeolite transformation from zeolite HY.Because this synthesis method can directly transform aluminum-rich HY into HZSM-5,there is no need to add an additional supplementary silicon source,which improves the utilization rate of inorganic atoms.In addition,compared with the HZSM-5 reported in the literature,the HZSM-5 zeolite catalyst synthesized by this method has high selectivity of BTX and long life for the methanol-to-aromatics reaction（MTA）.2.The FeAPO-44 molecular sieve with CHA topology was synthesized by solvent-free method,the effects of iron source type,P₂O₅/Al₂O₃ ratio,SDA/Al₂O₃ ratio（SDA:cyclohexylamine）,Fe₂O₃/Al₂O₃ ratio and Si O₂/Al₂O₃ ratio,crystallization temperature and crystallization time were studied in detail.The composition and structural characteristics of resultant FeAPO-44 molecular sieve with CHA-type were intensively by XRD,TG-DSC,CHN element analysis,EDS,SEM,and N₂ physical adsorption and desorption.Through CHN element analysis,EDS and TG-DSC determination,the approximate chemical formula of the synthetic sample SDA/Al-1.4 was calculate.The catalytic performance of the selected samples in the methanol-to-olefin reaction（MTO）was investigated.The results show that a proper P₂O₅/Al₂O₃ ratio,a lower SDA/Al₂O₃ratio（SDA:cyclohexylamine）and a relatively peaceable crystallization temperature are more conducive to the synthesis of pure CHA phase.3.The FeAPO-17/FeAPO-44 complexus molecular sieve material had been synthesized with the assistance of seed crystals under solvent-free conditions by using cyclohexylamine as the organic template,and the optimum synthetic conditions of this sample.XRD,SEM,N₂ physical adsorption and desorption and other characterization methods to characterize the structure and morphology of the synthesized samples,the results show that the introduction of seed crystals in a solvent-free system can reduce the size of the material,increase the surface area of materials.The introduction of heterogeneous seed crystals can reduce the amount of template in the synthesis of molecular sieves.