A novel fluidized bed technique for measuring UV Raman spectra of catalysts and adsorbates

To minimize interface from thermal degradation and photodegradation of adsorbates by UV radiation, a novel ″fluidized bed″ (FB) technique was developed for measuring UV Raman spectra of catalysts and adsorbates. UV Raman spectra were measured for benzene, pyridine, and naphthalene adsorbed in H-USY zeolite. The new method minimized the adverse effects of UV radiation. Measurements carried out on samples in the form of a stationary or spinning disc showed the presence of ″coke″, a typical end product of heating and photochemistry. However, the Raman peaks of the unreacted adsorbates dominated the spectra measured employing the FB apparatus. The UV Raman spectrum of n-heptane in H-ZSM-5 zeolite was measured. The technique should be applicable to a wide range of catalytic systems and can be adapted to perform in situ measurements under reaction conditions. It may also be utilized in other types of spectroscopies where sample damage due to the absorption of radiant energy is a major concern.