Synthesis and characterization of Al-MCM-41 supported Fe-Zr catalysts

The H2S gas which releases in many chemical processes is poisonous, causes acid rain and corrosive to the equipment in the process. H2S gas can be converted to elemental sulfur which is a useful product by selective catalytic oxidation. The aim of this study is development of a new, active, stable and selective Al-MCM-41 supported, Fe and/or Zr containing metal oxide catalysts for selective catalytic oxidation of H2S to elemental sulfur.In this study, the mesoporous material MCM-41 ("Mobil Composition of Matter") is used as a catalyst support material for its high surface area, controllable pore structure. Pure MCM-41 and aluminum containing MCM-41 materials were synthesized by hydrothermal method. Two different methods (Prescription-1 and Prescription-2) were applied for preparation of Al-MCM-41 material. For catalysts having different ratios of Al (Al / Si mole ratio: 0,2 and 0,05) in its structure, prescription-2 was used for hydrothermal synthesis of Al-MCM-41 material. Fe and / or Zr containing catalysts were prepared by impregnation method with loading metal by weight 15% to pure MCM-41 and Al-MCM-41 (Al / Si mole ratio: 0,1) materials. Moreover, Fe and Zr containing metal oxide catalysts were prepared by complex method without the use of support materials. Characterization studies (XRD, BET, EDS, SEM, XPS, TPR, FT-IR) were performed in order to determine the structural and the physical properties of synthesized catalysts. It is observed that, increment in the amount of Al in the MCM-41 structure, reduces surface area (1157-647 m2/g). Surface area of Fe-Zr catalysts which were prepared by MCM-41 support material approximately 10 times more than Fe-Zr catalysts prepared with complex method. In X-ray diffraction patterns of Al-MCM-41 materials which were prepared with Prescription-2, the characteristic peaks of MCM-41 structure were observed. In the XRD analysis of Al-MCM-41 supported catalysts, Fe2O3 peaks were observed when only Fe was present in the structure. However, the peaks of Fe and Zr were not observed when Zr alone or both Fe and Zr presence in the structure of Al-MCM-41 supported catalysts. The results of the EDS analysis for Al-MCM-41 catalysts and Fe-Zr containing catalysts was found to be consistent with the metal ratio of the synthesis solution.