Comparative techno‐economic analysis and process design for indirect liquefaction pathways to distillate‐range fuels via biomass‐derived oxygenated intermediates upgrading

Abstract

This paper presents a comparative techno‐economic analysis ( TEA) of five conversion pathways from biomass to gasoline‐, jet‐, and diesel‐range hydrocarbons via indirect liquefaction with a specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer‐Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include biomass‐to‐syngas via indirect gasification, syngas clean‐up, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass‐derived syngas to oxygenated intermediates occurs via three different pathways, producing: (i) mixed alcohols over a MoS ₂ catalyst, (ii) mixed oxygenates (a mixture of C _{2 +} oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh‐based catalyst, and (iii) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel‐range olefins in two approaches: (i) mixed alcohols/ethanol to 1‐butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and (ii) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2000 tonnes/day (2205 short tons) of dry biomass. The minimum fuel selling prices ( MFSPs) for the four developing pathways range from $3.40 to $5.04 per gasoline‐gallon equivalent ( GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co‐product credits and are comparable to the commercial Fischer‐Tropsch benchmark ($3.58/ GGE). Overall, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd