co hydrogenation on cobalt-based fisher-tropsch catalysts: chlorine poisoning reveals the nature of the most active sites

• Main Authors: Paredes-Numez, A., Lorito, D., Guilhaume, N., Schuurman, Y., Meunier, Frédéric
• Other Authors: IRCELYON-Ingéniérie, du matériau au réacteur (ING), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2016
• Subjects: [CHIM.CATA]Chemical Sciences/Catalysis; [SDE.ES]Environmental Sciences/Environmental and Society; Norway; Tromso
• Online Access: https://hal.archives-ouvertes.fr/hal-01327937

SSCI-VIDE+ING+APN:DLR:NOG:YSC:FRM International audience 1.IntroductionSynthetic fuels and base chemicals can be obtained from both fossil and renewable sources through the conversion of synthesis gas (syngas). Biomass-derived syngas contain significant concentrations of chlorine that may contaminate downstream catalysts. Rytter and co-workers reported that the presence of Cl introduced ex situ during cobalt-based catalyst preparation decreased the metal surface without, surprisingly, affecting activity, thus increasing the turnover frequency [1]. Davis and co-workers investigated the effect of alkali and chloride addition to a Fischer-Tropsch slurry phase reactor using a Co-based catalyst and noted a marked deactivation by halides and potassium [2]. The authors related the metallic cobalt poisoning to a blocking effect of metal sites by halides and potassium in agreement with results of H2 chemisorption obtained ex situ on used cobalt FT catalysts [2]. We report herein an operando diffuse reflectance FT-IR spectroscopy (DRIFTS) study in which the hydrogenation of CO is monitored in the presence of 150 ppm of chlorine. DRIFTS enables monitoring the state of the cobalt surface, which is typically covered with various carbonyl species under reaction conditions [3].2.ExperimentalThe preparation of the 14 wt.% Co/Al2O3 catalyst, experimental setup, DRIFTS cell and procedures are described in details elsewhere [3]. The hydrogenation of CO was performed at atmospheric pressure using a modified high temperature DRIFT cell. The reactor effluent was quantified using a 2 m-pathlength FT-IR gas cell. Methane, ethane, propene and methanol were the main reaction products in the present conditions and were quantified, while higher hydrocarbons were not monitored. The chlorine was introduced via a saturator held at -70°C containing trichloroethylene (TCE). Differential conditions were used, to ensure that the catalyst bed remained gradientless.3.Results and discussionThe rates of formation of the main products sharply ...