TRANSIENT SORPTION AND DESORPTION STUDIES OF CYCLOPROPANE AND PROPYLENE WITH CS/NAX AND NI/NAX ZEOLITES

Transient diffusion and sorption experiments of cyclopropane and propylene in Cs+and Ni2+ ion-exchanged Zeolites X in a flow microreactor reveal that the nature of the diluent gas affects the kinetics of intracrystalline mass transport of these molecules in the zeolite. The rate of intracrystalline mass transport and the equilibrium uptake are strongly dependent on temperature. The results indicate that cyclopropane does not react with either Cs+ or Ni2+ ion-exchanged Zeolites X in the range 40-240°C to give other gas-phase products. For Cs/NaX the enthalpy of sorption for cyclopropane at loadings approaching zero is -8.8 kcal/mol, and the entropy of sorption is -31.2 cal/mol-K. For Ni/NaX the enthalpy of sorption for both cyclopropane and propylene is - 9.1 kcal/ mol, and the corresponding values for the entropy of sorption are -30.8 and -29.8 cal/mol-K. © 1992.