Catalyst composition, activity and selectivity evolution of Fe-based catalysts during the formation phase in Fischer-Tropsch synthesis

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Thiessen, Johannes ; Rößler, Stefan ; Jess, Andreas:
Catalyst composition, activity and selectivity evolution of Fe-based catalysts during the formation phase in Fischer-Tropsch synthesis.
2016
Veranstaltung: DGMK Conference "Catalysis - Novel Aspects in Petrochemistry and Refining" , 26.-28.09.2016 , Berlin, Deutschland.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Poster )

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Abstract

Even though the Fischer-Tropsch synthesis (FTS) process is a mature technology that is currently being used for the production of synthetic fuels and other chemicals in industrial scale in several countries in the world, it is still not definitely known which is (or are) the active phase(es) catalyzing the reaction. Knowledge of the active phase thereby could have great advantages for designing a catalyst with optimal selectivity, durability, and activity. Determining the active phase, however, is challenging as FTS – catalysts (especially iron based) undergo restructuring processes during the reaction.
In this study, we examine in operando the development of the composition of two iron based catalysts during the formation period in Fischer-Tropsch synthesis under near to industrial reaction conditions (pH2 = 6 bar, pCO = 3 bar T = 220°C). Prior to the exposure to synthesis gas (CO/H2) the activation procedure was varied.
The formation of the Fe-containing phases in the catalysts, an industrial precipitated FT-catalyst (ARGE – catalyst) and a sintered Fe-catalyst were monitored via X-ray diffraction. Additionally, the activity and selectivity of the catalysts were measured in a lab scale fixed bed reactor using the same activation and reaction conditions as in the XRD-Measurements.
Differences in the formation of iron carbide phases, activity and selectivity in dependency of the reductive pre-treatment and catalyst synthesis method were identified.