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Synthesis of a faujasite thin layer and its application for SO2 sensing at elevated temperatures

1998; Elsevier BV; Volume: 23; Issue: 5-6 Linguagem: Inglês

10.1016/s1387-1811(98)00125-5

1873-3093

Mayuka Osada, Isao Sasaki, Masateru Nishioka, Masayoshi Sadakata, Tatsuya Okubo,

Acoustic Wave Resonator Technologies

A faujasite thin layer is synthesized on a quartz crystal microbalance (QCM) with an Au electrode without seed crystals, and applied to a gas sensor. Faujasite synthesis is often accompanied by the production of zeolite P as a by-product, which would be an obstacle for gas sensing. Seed crystals tend to result in an irregular layer structure which is unfavorable in view of the stable oscillation of the QCM. In this study, therefore, the synthesis conditions (i.e. composition of the synthesis solution, aging time and reaction time) are optimized so that the minimum amount of zeolite P is yielded. After optimization of the synthesis conditions, the synthetic faujasite layers on a QCM with a fundamental resonance frequency of 5.4 MHz frequency are installed into the oscillating circuit. When SO2 gas molecules are adsorbed on the faujasite layer, the mass increase reduces the QCM frequency. Since the frequency shift of the QCM is proportional to the amount of SO2 adsorbed, the gas-phase concentration can be measured from the shift. Preliminary sensing results regarding the influence of SO2 concentration and the coexistence of O2 are reported.