合成ゼオライトの熱脱着による吸着特性の変化

抄録

Relationship between the adsorption characteristics of synthetic zeolites and a number of water adsorption-desorption cycles was investigated with a specially designed test apparatus illustrated in the text.
The Na-A, (Na, K)-A and faujasite type synthetic zeolites were stable in their crystal structure at a temperature of 700°C for more than several days under the atmospheric condition. However, water adsorption rate of (Na, K)-A type zeolite after repeated several tens of water adsorption (at the room temperature)-thermal desorption cycles (below 300°C) in the apparatus was considerably decreased with increasing the number of cycles, scarcely adsorbing methanol. In the case of Na-A type zeolite after the same treatment, the propylene adsorption rate was decreased, but the decrease of water adsorption rate was not observed. The crystal structures of both resultant zeolites were preserved, as confirmed by X-ray diffraction.
From these results, it is believed that the pore size of zeolite shrinked, these phenomena being attributable to the influence of high temperature water vapor that was generated from the zeolite during the thermal desorption process.
Faujasite type synthetic zeolite, treated in the same apparatus under the same conditions, was investigated for adsorption of 1, 3, 5-trimethylbenzen, but no such phenomenon as in the case with the A-type zeolite was observed.