Study Of Preparation And Catalytic Activity Of Modified MCM-48 And Synthesis Of Y/MCM-48

This thesis consists of three parts. In the first part, the modified MCM-48 framework containing Ni, Sn, Fe and V were synthesized and characterized. The catalysis behavior of Fe-MCM-48 and V-MCM-48 for the hydroxylation of benzene were studied. The results showed that amount of metal ions and the adding order of materials affected the Mesoporous structure obviously, whereas the different salts containing the same metal ion affected slightly the structure of sample. In addition, Fe-MCM-48 and V-MCM-48 showed a relatively high catalysis activity.In the second part, the supported mesoporous sieve solid base KNO₃/MCM-48 and KAc/MCM-48 were prepared. And it was the first time that KNO3/MCM-48 and KAc/MCM-48 were used as catalysts for the synthesis of dipropyl carbonate (DPC) by transesterification of propanol and dimethyl carbonate. The effects of potassium loading and calcinated temperature on structure of the support MCM-48 were investigated. The effects of the potassium loading, the base strength of potassium salts, the catalyst dosage, the calcinated temperature and reaction time on the catalysis performance were also studied. It indicated that both KNO3/MCM-48 and KAc/MCM-48 performed very high catalytic activities. Under optimized reaction conditions: reaction temperature 363K, propyl/DMC mol ratio 4/1, reaction time 6h, K% 15% .catalyst content 5% and calcinated temperature 673K, the conversion of DMC was about 96.0% and the yield of DPC was 91.1% respectively by using KAc/MCM-48 as catalyst. Under above conditions and calcinated temperature 823K , the conversion of DMC was about 99.9%, the selectivity of DPC was 93.4%, and the yield of DPC was 93.3% respectively by using KNO₃/MCM-48 as catalyst.In the third part of this thesis, the synthesis of the composite molecular sieve Y/MCM-48 was studied. It was the first time that the composite Y/MCM-48 was synthesized by adding NaY zeolite into the sol of MCM-48. The results of XRD and analysis of pore structure as well as IR showed that the composite sample contained two kinds of pores: micropore and mesopore. However, the sample was not same as simple mixture of NaY and MCM-48. The result of TPD indicated that MCM-48 only showed one kind of acid site and its acid strength was very weak, but the composite sample had two different kinds of relatively strong acid site. The test of hydrothermal stability showed that the composite Y/MCM-48 performed a higher stability than the pure MCM-48.