| Research Abstract |
Clean chemical processes are one of key technologies for sustainable growth of industry. Zeolites are the most important candidate for the purpose. It is important to find new types of zeolite with large pores to establish new era of the zeolite catalysis, . We devote to synthesize new types of zeolite and to understand the mechanism of zeolite catalysis.
1) Shape-selective formation of 4,4'-diisopropylbiphenyl (4,4'-DIPB) was observed in the isopropylation of biphenyl over H-mordenite (HM). The shape-selectivity was governed by spatial restriction at transition states in HM pores. The selectivity for 4,4'-DIPB was influenced by many factors such as SiO_2/Al_2O_3 ratio, reaction temperature.
2) The high selectivities for 4,4'-DIPB in encapsulated products were observed because of shape-selective catalysis inside HM pores. The decrease of the selectivity for 4,4'-DIPB occurred with the increase of temperature : The decrease was ascribed to the isomerization of 4,4'-DIPB at the external ac
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id sites.
3) Two organic templates were used as SDA for the synthesis of all-silica MTW.These templates gives MTW crystals with different stacking sequences. This is ascribed to the difference in the properties related to organic-silica interaction as well as other inorganic factors.
4) 1,1'-Butylenedi (4-aza-1-azonia-2,5-dimethylbicyclo [2.2.2] octane) was used as structure-directing agent (SDA) for zeolite synthesis. A new phase (GUS-1) within ZSM-12 phase is obtained from all-silica crystal. GUS-1 is indexed in the orthorhombic crystal class with refined lattice constants a=16.4206(4), b=20.0540(4), and c=5.0464(1) Å. Framework topology of GUS-1 was reported in the Database of Zeolite Structures by IZA under the code GON.
5) Synthesis of high-silica [Al]-SSZ-31 zeolite by dry-gel conversion method was found to be dependent on the alkali concentration of the initial gel, and a phase change from BEA to SSZ-31 to MFI was observed with time course at optimum alkali concentration. A phase transformation from BEA to SSZ-31 was observed when the crystallization temperature was changed from 150→C to 175→C. Less
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