Zeolite dehumidifier

The HYSEC Process was developed by Mitsubishi Kakoki K. Ltd. and The Kansai Coke Chemicals Company. It has basically the same PSA unit as the UCC Process. It has prefilter beds with activated carbon that remove dirty components. After the main PSA beds, trace amounts of remaining oxygen are removed by a deoxo catalytic converter followed by a zeolitic dehumidifier. A Ni-LaaOj-Rh catalyst, supported on silica, could lower the reaction temperature to about 30°( a. 

Zeolite monoliths have been useful for such apphcations as rotatory adsorbers for use as dehumidifiers and desiccant cooling processes [253] or in VOC treatment systems [269]. Alumina-coated sUicon carbide monoliths have also been employed as supports for B-ZSM-5 membranes [270] providing a larger surface area per unit volume, compared to traditional membrane supports. With these membranes, these authors have reported n/f-butane and H2/f-butane separation selectivities of 35 and 77, respectively [85]. Also, silicalite-1 membranes supported on stainless steel grids (Figure 10.29) have shown a good performance in the separation of n/f-butane mixtures, with separation factors as high as 53 at 63°C [255]. 

Most dehumidifying dryers used in the plastics industry today employ a molecular sieve desiccant. A molecular sieve is a synthetic zeolite, which has a very strong attraction for water across a certain temperature range. When the temperature of the molecular sieve is maintained at a reasonably low level (under 150°F), such as when it is in the on-stream drying position, it will adsorb moisture readily. When the molecular sieve temperature is increased above 400°F, as is the case during regeneration, it will release its adsorbed moisture. Figure 7.39 shows how temperature dramatically affects desiccant s ability to hold moisture. 

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