NipponKagakuKaishi_1997_456.pdf 3.39 MB
Estimation of Proton Mobility in HZSM-5 Type Zeolite Films by Complex Impedance Method <Note>
The delocalization of protons in HZSM-5 type zeolite films was investigated by the complex impedance method. The conductivities under various water vapor pressures were calculated from both the Cole-Cole plot analysis and the impedance at 1 kHz. The conductivity of HZSM-5 (Al) zeolite film with 170 of SiO2/Al2O3 ratio was strongly dependent on the water vapor pressure and increased with an increase inthe vapor pressure. On the other hand, the conductivities of the silicalite film (SiO2/Al2O3 ratio > 5000) and the pellet prepared by compressing the powdery HZSM-5 zeolite with 173 of SiO2/Al2O3 ratio hardly increased with the water vapor pressure. The conductivities of HZSM-5 type metallosilicates (HZSM-5 (Ga) and HZSM-5 (Fe)) films were also measured. From the results obtained, it was concluded that (1) the acidic sites associated with the framework aluminums are the active centers for the proton conductivity, (2) adsorbed water molecules are responsible for the conduction and (3) the polycrystalline zeolite film is very effective for estimation of proton mobility.
Journal of the Chemical Society of Japan : chemistry and industrial chemistry
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Copyright (c) 1997 The Chemical Society of Japan
Graduate School of Engineering