Adsorption behavior of water and xylene isomers on AlPO-5 zeolite modified by different transition metals

摘要

This work deals with the preparation of MAPO-5 zeolite by a hydrothermal method. In order to study the adsorption properties of this zeolite several transition metals (Fe, Co, Ni, Mn and Zn) were incorporated by a direct route. The obtained zeolites were characterized by various physico-chemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, adsorption/desorption of argon, thermogravimetric analysis/differential thermal analysis, scanning electronic microscopy(FEG-ESEM) and Inductively coupled plasma-optical Emission spectrometry (ICP-OES). The prepared zeolites were tested for adsorption of water and xylene isomers (ortho-, para- and meta-xylene). The obtained results showed that the isomorphic substitution of the transition metals in the framework of the zeolite has been achieved with different levels of metals. The isomorphic substitution by zinc showed the best results in terms of the percentage of the incorporated metal, while the substitution by cobalt presented the lowest rate of incorporation in the framework of the zeolite CoAPO-5. The adsorption of water in the vapor state on the zeolite substituted by Ni, Fe and Zn has presented the best adsorption capacity. The adsorption of xylene isomers on MAPO-5 showed different isotherms, confirming that the adsorption behavior differs from one zeolite to another. ZnAPO-5 showed higher adsorption capacity for all xylene isomers with slight selectivity towards meta-xylene.