FTIR study of toluene adsorption on Cs-exchanged mordenites

The adsorption capacity of toluene on Cs-exchanged mordenite and the interaction of the hydrocarbon molecules with the adsorption sites were studied. For this purpose, flow-adsorption measurements were performed to obtain breakthrough and TPD curves. A detailed FTIR characterization of adsorbed toluene was also carried out. The results show that the interaction between the toluene ring C=C bond and the basic sites and steric restrictions originated in the formation of Cs oxides modulates both the adsorption capacity and the retention strength of the samples. The exchange of Cs in both the NH4MOR and NaMOR samples decreased the toluene adsorption capacity at 100 degrees C but increased the retention strength at higher temperatures. Samples derived from the Cs-exchange in NaMOR showed higher retention strength than those obtained from NH4MOR due to the higher basicity of the former. On the other hand, the CsNaMOR sample containing 19 wt.% of Cs showed a lower retention strength at high temperatures if compared to the samples containing 7 wt.%. This suggests an optimal basicity in samples with intermediate levels of Cs loading. (C) 2009 Elsevier Inc. All rights reserved.