Study On The Properties Of Organic Molecules In The Confined Region Of Zeolites Channel

Zeolites have attracted great interest in industry field because of their unique structures and properties.Efficient use of zeolites is always a concern in this field.Zeolites are generally synthesized in the presence of organic structure directing agent(SDA).These organic molecules usually trapped in zeolite void space during synthesis process.In the traditional study,these organic species are calcined and removed.The similarities and differences of the states and properties of the organic molecules instricted in zeolites and the free organic molecules are rarely studied,resulting in the insufficient understanding of the nature organic molecules in the limited space and their application.Therefore,it is a new and practical work to use organic species trapped in the zeolite channel directly.In order to directly utilize the organic molecules in the zeolite channel and broaden the application field of the zeolite,it is very important to study the state and properties of the organic molecules in the zeolite channel.In this dissertation,four kinds of organic molecules are used as SDAs and two different structural types of zeolites were synthesized in the presence of an organic SDA.Characterizations of the as-synthesized samples were investigated.The zeolites were analyzed by X-ray diffraction,vibration spectroscopy,nuclear magnetic resonance spectroscopy,elemental analysis,thermal analysis and computational simulation.Furthermore,the zeolites were oxidized by different oxidizing agents.Based on the comparison and analysis of different oxidation products,it is confirmed that the state and properties of the organic molecules in the zeolite channel are affected by the shape and size of the pores,the framework structures and Si/Al ratios.It can also provide some theoretical basis for the development of zeolite microreactor and the application of organic molecules in zeolite channels.The main results are as follows.(1)ZSM-5 zeolite and ferrierite were synthesized by using n-butylamine(chain primary amine)as SDA.Characterization and simulation calculations indicate that n-butylamine is occluded in its protonated form together with dibutylamine in ZSM-5,while incorporated intact in its protonated form in ferrierite.Furthermore,the oxidation of n-BA restricted in zeolites by H2O2 was studied.It was found that the restricted organic species were partly oxidized.The oxidation product of organic trapped in ZSM-5 was hydroxylamine,whereas unchanged in ferrierite.The adsorption capacity of nickel ion after oxidized ZSM-5 zeolite and ferrierite increased by 6 times and 1.5 times before oxidation,respectively.(2)Ferrierite,silica-sodalite and aluminosilicate sodalite were synthesized by using ethylene glycol(alcohol)as SDA.The oxidation by H2O2 and HIO4 of ethylene glycol restricted within these zeolites has been studied.It was found that the restricted ethylene glycol molecules in the two sodalites remained unchanged during the oxidation process.In ferrierite,the oxidation products were alkanes and other alcohols by H2O2,whereas alkynes,acetals and ketals produced by HIO4.(3)ZSM-5 zeolite and mordenite were synthesized from cyclohexylamine(cyclic primary amine)as SDA.It was found that cyclohexylamine was trapped in the two zeolites in its protonated state together with some other organic species.The oxidation of cyclohexylamine restricted in zeolites by H2O2 was studied.The oxidation products of restricted cyclohexylamine were nitro compound and saturated hydrocarbons in mordenite,whereas nitro compound,cyclanes and amines in ZSM-5.The adsorption capacity of the oxidized mordenite to the nickel ion increased from 6.62 mg/g to 28.06 mg/g.The oxidized ZSM-5 zeolite increased from 53.66 mg/g to 62.14 mg/g.(4)Mordenite and AlPO4-5 were synthesized by using hexamethyleneimine(cyclic secondary amine)as SDA.In this system,AlPO4-5 was synthesized using hexamethyleneimine as SDA for the first time.Furthermore,the oxidation of hexamethyleneimine restricted in the two zeolites by H2O2 has been studied.It was found that the restricted hexamethyleneimine molecules are changed into saturated hydrocarbons and some other amines in AlPO4-5,whereas unchanged in mordenite.The oxidized mordenite is similar to the adsorption capacity of nickel ions before oxidation,and the oxidation of AlPO4-5 increases from 19.37 mg/g to 27.41 mg/g compared with that before oxidation.For the adsorption of Ni cations,the zeolites without SDA have one process on removal of Ni(?)taking place via ion-exchange.The as-synthesized and the oxidized zeolites contain both complexation and ion-exchange processes.In this dissertation,four kinds of organic molecules are used as SDAs and two different structural types of zeolites were synthesized in the presence of an organic SDA.Furthermore,the zeolites were oxidized by different oxidizing agents.By analyzing the similarities and differences between the organic molecules in the different zeolites and the oxidation products,it is explained that the state and properties of the organic molecules restricted in the zeolite are influenced by the framework structures,Si/Al ratios and the shape and size of the pores.This work opens new opportunities for further research of molecular reactions on the inorganic hybrids,and provides a new idea for the application of SDAs present in zeolites.