Adsorption of Water and Methanol on a NaZSM-5 Zeolite. A temperature-programmed desorption (TPD) study

Using temperature-programmed desorption (TPD), we have investigated the desorption behavior after subsequent co-adsorption of methanol and water and after adsorption of their mixtures on a NaZSM-5 zeolite. The course of desorption indicates that a strong mutual displacement of both components occurs. However, on the strongest adsorption sites methanol is preferentially adsorbed, and already the addition of small amounts of methanol leads to a displacement of water. Our results support the idea of a subdivision of the pore space for adsorption of water/methanol mixtures. Above all, the experiments show that in the part of the pore space where both components are adsorbed, different sites are of importance which vary significantly in their interaction strength. This revised version was published online in July 2006 with corrections to the Cover Date.