Synthesis Gas Purification
Abstract
Fischer-Tropsch (FT) based B-XTL processes are attractive alternatives for future energy
production. These processes aim at converting lignocellulosic biomass possibly in
co-processing with petcoke, coal, or vacuum residues into synthetic biofuels. A
gasification step converts the feed into a synthesis gas (CO and H2 mixture) ,
which undergoes the Fischer-Tropsch reaction after H2/CO ratio adjustment and
CO2 removal. However synthesis gas also contains various impurities that must
be removed in order to prevent Fischer-Tropsch catalyst poisoning. Due to the large feedstocks variety that can be processed, significant variations of the
composition of the synthesis gas are expected. Especially, this affects the nature of the
impurities that are present (element, speciation), as well as their relative contents.
Moreover, due to high FT catalyst sensitivity, severe syngas specifications regarding its
purity are required. For these reasons, synthesis gas purification constitutes a major
challenge for the development of B-XTL processes. In this article, we focus on these major hurdles that have to be overcome. The different
kinds of syngas impurities are presented. The influence of the nature of feedstocks,
gasification technology and operating conditions on the type and content of impurities is
discussed. Highlight is given on the fate of sulfur compounds, nitrogen compounds,
halides, transition and heavy metals. Main synthesis gas purification technologies (based
on adsorption, absorption, catalytic reactions, etc.) are finally described, as well as
the related challenges.
Domains
Physics [physics]
Origin : Publication funded by an institution
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