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Modified Zeolites in Gas Chromatography for the Analysis of Air Pollutants

Based on zeolites of types X, Y and M, with and without binding clay, ion-exchange modifications containing alkali and alkaline earth cations (silver and copper) and different quantities of water have been prepared. Data obtained with these zeolites have enabled their retention volumes and selectivities towards low boiling hydrocarbons and oxide gases to be calculated. Sharp changes were observed in these parameters when the chromatography of ethane and other gases was conducted on such zeolites with up to 10% K+, Rb+ and Cs+ cations replaced, i.e. when low replacement of exchangable cations had been effected. The same effect was encountered with CO and olefins when 0.08CuNaY zeolite was employed. An increase in temperature and the introduction of water into the system caused a decrease in the effect. These observations have prove useful in the construction of chromatographic columns and adsorption filters for the extraction and concentration of certain pollutants.