Adsorption of isobutane and isobutene over ZVM, Beta, and Y zeolites

The adsorption of isobutane and isobutene (mixtures of 2 vol % in nitrogen) on catalysts based on commercial batches of ZVM, Beta, and Y zeolites has been studied by flow adsorption calorimetry (using the temperature difference between the adsorbent bed and the gas over the bed). The isobutane adsorption for the zeolites subjected to calcination at 500°C increases in the order NaY > HZVM > HBeta >CaLaHY and correlates with the specific surface area. The adsorption of isobutene, compared to that of isobutane, takes a significantly longer time and depends on the acidity of the zeolites. It has been found that the isobutene adsorption is characterized by a long lag, which is linearized by raising time to the power of 0.5. The effect of the dehydration temperature of CaLaHY on the adsorption behavior of isobutene has been revealed: a decrease in the dehydration temperature from 500 to 130°C leads to an increase in the initial temperature jump during adsorption and the disappearance of the time lag.