ADSORPTION ON MCM-41 MESOPOROUS MOLECULAR-SIEVES .2. CYCLOPENTANE ISOTHERMS AND THEIR TEMPERATURE-DEPENDENCE

The effect of temperature on adsorption isotherms of cyclopentane on m esoporous MCM-41 molecular sieves with different pore size has been de termined at 243-333 K. The occurrence of adsorption hysteresis upon ca pillary condensation in mesopores depends on the pore critical tempera ture, which is lower than the bulk critical temperature and decreases with decreasing pore diameter. If the pore critical temperature is wit hin the range of experimental temperatures of adsorption, capillary co ndensation on a single sieve may occur both reversibly (hypercritical region) and irreversibly (subcritical region).