Photocatalyst reactor

The effect of wavelength of the UV light (germicidal white and fluorescent black lamps) on TCE conversion in the CFB photoreactor is shown in Fig. 6. As can be seen, the germicidal white lamp (254 nm) exhibits higher TCE conversion than the fluorescent black lamp (365 nm). It has been reported that variation of photon energy in excess of band gap of TiC>2 does not affect the product mixture from a photocatalyst reactor [12]. The increase of TCE conversion is caused by higher photon flux, rather than by increases... 

State of the photocatalyst reactors with suspended photocatalyst particles (slurry) and reactors with photocatalyst immobilized on the inert surfaces... 

Figure 2 shows the result of an experiment without photocatalyst where the reactor tenperature was maintained at 97°C during the run. Note that conversions of methane remain relatively constant at - 4% and production of hydrogen, methanol, oxygen, and carbon monoxide remain constant during the ejqjeriment. The large oscillations in the conversion of methane and the production of methanol were not observed during this ejqjeriment. 

All of the following ejqperiments were conducted with the photocatalyst and electron transfer agent in the reactor. 

In sensitized or photocatalyzed reactions, conditions of total or constant absorbance can easily be controlled by the concentration of the sensitizer or photocatalyst added. In addition, experience has shown that the concept of spatial separation between the light source and the reaction mixture is in general not required. Dragoco uses immersion-type annular reactor geometries [2, 3, 69, 70] for the production of ( —)-rose oxide by rose bengal sensitized oxidation of (— )-citronellol (Eqs. 45-48, Figure 23). 

In designing modules of mono- or multilamp immersion-type photochemical reactors, again the concept of convergence of light distribution and reactor geometries is followed, and knowledge of light penetration in a suspension of optimal photocatalyst concentration is therefore essential. Optimal thickness of annular irradiated reaction volume is best determined by a spherical probe under conditions where only absorption by the photocatalyst has to be taken into account [12, 78, 98, 99]. The radiant power P = f(r) within the limits of r and rR, respectively, has been simulated by the Monte Carlo method on the basis of... 

A prototype treatment system of NC consists of four 40-W fluorescent lamps which are radially equipped with four sheets of P i Ft, photocatalyst (total area of 18 m2) and shower nozzles over the lamps/reactors as well as a reservoir, which are used for washing the photocatalyst sheets periodically. A reaction gas prepared from diesel engine exhaust, containing about 2 ppir of NO is introduced into the reactors at a flow rate of 1.0 m s-1 for 10 hours. As shown in Fig. 8.25, although the NO removal ratio seemed to decline slowly after 6 h, the average NO removal ratio obtained was 77.7%. About 80% of NO was recovered as nitrate and nitrite ions by the catalysts using the shower systerr. 

Fig. 12.2 Time dependencies of sonophotocatalytic reaction products from pure water. As powdered photocatalyst, Ti02-A (200mg, Soekawa, Commercial Reagent, rutile-rich type and specific surface area 1.9 m2/g) was used without further treatment. Liquid water (150 cm3, Wake, Distilled water for HPLC was used as reactant and was purged with argon, a Pyrex glass bulb (250-300 cm3) was used as a reactor and was placed m a temperature-controlled bath (EYELA NTT-1200 and ECS-0) all time. After the glass bulb was sealed, the irradiation was carried out under argon atmosphere at 35°C. Photo and ultrasonic irradiations were performed from one side with a 500 W xenon lamp (Ushio, UXL500D-O) and from the bottom with an ultrasonic generator (Kaijo. TA-4021-4611, 20C kHz 200 W), respectively.

Bekbolet, M., Lidner, M., Weichgrebe, D., and Bahnemann, D., Photocatalytic detoxification with the thin-film fixed bed reactor clean up of highly polluted landfill effluents using a novel Ti02 photocatalyst, Solar Energy, 56(5), 455, 1996. 

The idea of using fluidized bed as both uniform light distribution and an immobilizing support for photocatalysts has been originally proposed and theoretically evaluated by Yue and Khan [3]. Experimental application of this idea has been demonstrated by Dibble and Raupp [4] who designed a bench scale flat plate fluidized bed photoreactor for photocatalytic oxidation of trichloroethylene (TCE). Recently, Lim et al. [5,6] have developed a modified two-dimensional fluidized bed photocatalytic reactor system and determined the effects of various operating variables on decomposition of NO. Fluidized bed photocatalytic reactor systems have several advantages over conventional immobilized or slurry-type photocatalytic reactors [7,8]. The unique reac-... 

The coupling of photocatalysis and polymeric membranes has been carried out using Ti02 as photocatalyst compartmentalized in the reactor by a membrane [39]. Various types of commercial membranes (ranging from UF to NF) and reactor configurations have been investigated [39]. 

Various types of photocatalytic membrane reactors in which the catalyst was used in different modes have been built with the purpose to have an easy separation of the catalyst from the reaction environment a photocatalyst in suspension in magnetically or mechanically agitated slurries confined by means of a membrane, fixed bed, catalyst deposited or entrapped on an inert support or in a membrane, and so on. 

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