Novel single pass biogas-to-diesel process using a Fischer-Tropsch catalyst designed for high conversion

• Published in: Sustainable energy & fuels 2021-11, Vol.5 (22), p.5717-5732
• Main Authors: Tucker, Chelsea L, Bordoloi, Ankur, van Steen, Eric
• Format: Article
• Language: English
• Subjects: Air separation; Aluminum oxide; Biogas; Carbon dioxide; Carbon monoxide; Catalysts; Cobalt; Compressing; Diesel fuels; Fischer-Tropsch process; Fuel production; Manganese; Platinum; Remote regions; Selectivity
• ISSN: 2398-4902; 2398-4902
• DOI: 10.1039/d1se01299a

The decentralized production of low carbon fuels using the Fischer-Tropsch synthesis requires a less complex and more cost-effective process design. This can be achieved by operating the Fischer-Tropsch process in single pass mode ( i.e. , without recycle), which allows for omission of the air separation unit, CO 2 removal step and the energy-intensive recompression. However, single pass mode necessitates operating the Fischer-Tropsch synthesis at a higher CO conversion than typically seen in industry (resulting in high H 2 O and low CO and H 2 partial pressures). These harsh conditions cause a significant decrease in the C 5+ yield as a consequence of the increase in the selectivity for the formation of CH 4 and CO 2 . Modification of an industrial Pt-Co/Al 2 O 3 catalyst with manganese resulted in increased fuel production of up to 14 C-% under high conversion conditions. Here, we present a technical analysis of a novel single pass biogas-to-diesel process that can operate off-grid in remote regions, focusing on counteracting the loss of yield under single pass operation by adjusting the Fischer-Tropsch conversion ( X CO = 60-90%), catalyst characteristics (Pt-Co/Al 2 O 3 vs. Mn-Pt-Co/Al 2 O 3 ) and refining configuration (with and without a hydrocracker). The optimal case, X CO = 80% using a Mn-Co/Al 2 O 3 catalyst results in a production rate of 246 bbl per day of on-spec distillate from 400 kmol h −1 biogas together with the net power generation of 1.8 MW. Single pass Fischer-Tropsch biogas-to-diesel process for off-grid fuel production in remote regions. Diesel yields optimized by operating at a higher-than-industrial CO conversions of 80% with a manganese-promoted cobalt catalyst.