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Εffect οf the suppοrt οn the activity and mοrphοlοgy οf hydrοdesulfurizatiοn catalysts

Abstract : The influence of the support effect on the sulfide phases formation, i.e. morphology, sites dispersión, structure and catalytic activity for hydrotreating catalysts was studied. The study started by Mo catalysts and followed by CoMo catalysts supported on alumina silica and titania. The support effect appeared to be the key factor to control the morphology of MoS2 slabs. The morphology was studied using a powerful technique so-called IR/CO, i.e. CO adsorption followed by FTIR spectroscopy. This method allows the distinction of two types of edge exposed on the MoS2 slabs so-called M- and S-edge and then permits the study of the morphology by the S-/M-edge ratio. Thus, for a weak interaction MoS2-support deformed hexagon morphology was detected whereas for a strong interaction triangle morphology was observed. These different morphologies were used to study the Co localization by the same method, IR/CO. This method also allows the distinction between non- and promoted sites as well as Co located on M- and S-edges. Hence, the comparison between S-/M-edge ratio and promotion degree (promoted/non-promoted sites ratio) showed that Co is present on both M- and S-edges for the three CoMo supported catalysts. Additionally, a detailed study showed that Co preferentially decorates S-edge sites. Consequently, the CoMoS site structures for each catalyst has been studied by 2D IRIS method. This novel method developped in LCS allows the resolution of overlapping IR/CO bands which were previously a limitation for CoMoS sites characterization. This advance in the CoMo characterization lead to the study of detailed CoMoS structure. After the assignment of three bands which are observed in the promoted range of IR/CO spectra, it appeared that S-edge sites were partially promoted by Co, whereas M-edge sites could be partially and totally promoted by Co. The different proportion of those sites have an effect on HDS (hydrodesulfuration) reactivity. Thus, higher intrinsic activity was found for M-edge partially promoted by Co followed by totally promoted and finally the S-edge partially promoted sites.
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Submitted on : Monday, March 12, 2018 - 12:46:14 PM
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  • HAL Id : tel-01729093, version 1

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Elizabeth Dominguez Garcia. Εffect οf the suppοrt οn the activity and mοrphοlοgy οf hydrοdesulfurizatiοn catalysts. Organic chemistry. Normandie Université, 2017. English. ⟨NNT : 2017NORMC258⟩. ⟨tel-01729093⟩

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