Sorption of benzene in CeNaY zeolite under catalytic conditions

Abstract

Sorption isotherms of benzene in CeNaY (Ce³⁺-exchange: 72%) and in the same zeolite with its stronger acid sites poisoned with pyridine were obtained in the temperature range 463-623 K by the gas Chromatographic pulse technique using the peak maximum method. The sorption data could be fitted well to the Langmuir type sorption equation. The isosteric heats of sorption at different sorbate loadings were evaluated from the sorption data. The heat of sorption at near zero intracrystalline sorbate concentration was obtained separately by gas Chromatographic technique. Temperature-programmed desorption (TPD) of benzene from the zeolite under Chromatographic conditions at different initial sorbate loadings were also investigated. The poisoning of the stronger acid sites of the zeolite has resulted in a very significant decrease in the extent of sorption and in the heat of sorption, indicating the involvement of the acid sites in the sorption. The variation of the isosteric heat of sorption with the sorbate loading, the TPD data and the analysis of pressure derivatives of the sorption clearly show the presence of site energy distribution in the zeolite.