Synthesis Gas Production via Reverse Water-Gas Shift : Co-Conversion of Gaseous Hydrocarbons

Titelangaben

Wolf, Andreas ; Kern, Christoph ; Jess, Andreas:
Synthesis Gas Production via Reverse Water-Gas Shift : Co-Conversion of Gaseous Hydrocarbons.
2015
Veranstaltung: DGMK International Conference "Synthesis Gas Chemistry" , 07.-09.10.2015 , Dresden, Deutschland.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Vortrag )

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Abstract

Conversion of CO₂ (e.g. separated from flue gases of power plants) and regenerative hydrogen (electrolysis) into liquid hydrocarbons (HC) is a promising concept for substituting fossil fuel in the transport sector. Such a synthesis requires two process steps:
1) Syngas production via reverse water-gas shift (RWGS)
2) Synfuel production by Fischer-Tropsch (FTS)
As product, a wide range of gaseous, liquid and waxy HCs is gained. Liquid HCs are the most valuable and, therefore, desired products; thus, a process optimization towards maximum yield of liquid HCs is aspired. The waxy products can be liquefied in a downstream hydrocracking process. For the gas fraction, consisting of H₂, CO, CO₂ and CH₄, thermodynamic considerations suggest a recycle of this fraction into the RWGS unit; here, the gaseous compounds can be co-converted to syngas via steamreforming (with RWGS product water). Apart from thermodynamics, this work examined the catalytic activity and stability of the RWGS catalyst (Ni) in the presence of short chain hydrocarbons, namely CH₄ and C₃H₈, inside the RWGS unit. The catalyst showed a stable performance for the conversion of CH₄, even under dry conditions, as long as the CH₄-to-CO₂ ratio was below 1. However, propane led to catalytic coke formation which eventually caused catalyst deactivation. Thus, the influence of different oxidants on coking was examined, and it was found that coke formation can be effectively suppressed with additional H₂O in the feed gas.