Preparing Of Efficient And Green Beta Zeolite And Its Application

Beta Zeolite has found widespread use in petrochemical applications.Beta zeolite was usually synthesized in the presence of alkali cations.But the process to get proton-type Beta zeolite is very complicated and produces a great amount of waste water including ammonia-nitrogen,which puts great stress on the environment.And incorporating mesopores in microporous materials is a promising method for eliminating transport limitations to improve catalytic performance.Therefore,a comparative study on preparing of efficient and green Beta zeolite was carried out in this thesis and it can be included into the following two parts:Firstly,the Beta zeolite was successfully synthesized using a novel method with the aid of colloidal seeds in sodium free system.The obtained materials possess higher crystallinity,smaller crystal size and a large amount of mesopores.And this method has the characteristics of shorter crystallization time,higher solid yield and less waste water.The obtained Beta zeolite shows excellent catalytic activities in the alkylation of benzene with ethylene and the cracking of bulk molecule.Secondly,alkaline treatment is proved to be an efficient and controlled method to incorporate mesopores into microporous framework.In order to make alkaline treatment process more controlled and protect zeolite framework,we prepare hierarchical structured Beta zeolite with TEAOH as alkaline solution in sodium free system.The preferred hierarchical Beta zeolite possesses higher specific surface area(610 m2/g)and volume of mesopore(0.58 cm3/g).Compared with microporous Beta zeolite,hierarchical Beta zeolite shows a significantly higher activity in the cracking of bulk molecule.