BIV 05: Catalytic conversion of bio-derived feedstocks to bio-LPG component gases
- Project lead
- Jude Onwudili
- Aston University
LPG is a clean burning lower-carbon fuel and due to the low emission of particulate matter and other pollutants during its combustion, promotes better air quality. There is an urgent need to develop bio-based low carbon pathways to C3 and C4 hydrocarbons to replace the existing use of liquefied petroleum gases (LPG). With a global market value of US$125 billion1, LPG has a huge potential to help meet decarbonisation targets. According to the Liquid Gas UK (LGUK)2, 2 million UK off-grid homes have limited space and water heating options, making LPG their fuel of choice. It is also the common heating and cooking fuel among urban dwellers in other communities not connected to the natural gas network. LPG consists mainly of propane and butane in different proportions. There are ongoing research efforts3 to defossilise LPG by producing its component gases from biomass and biomass-derived feedstocks, in which case it is described as BioLPG. This is an emerging research area, which if successful and economically viable, will contribute to UK’s and international decarbonisation efforts to meet zero carbon emission targets by 2050. Already, existing LPG producers and distributors have shown significant interests in this type of research. For instance, Calor Gas are supporting this research by providing match-funding of up to £16k for this initial work for 6 months.
Recent results from the PI’s research group have shown that biopropane (one of the LPG component gases) can be produced from the decarboxylation of butyric acid using commercial platinum-based catalysts. Butyric acid is an intermediate product of a time-tested acetone-butanol-ethanol (ABE) fermentation process (submitted for publication). Since the ABE process is designed for producing these green solvents, the amount of butyric obtained from this process is relatively small. While, the ABE process could be modified or disrupted to increase the yield of butyric acid, it has become important, identifying and using other more commonly available bio-derived molecules to make bio-LPG offers a good prospect in terms of process and product economics. In this project, the PI’s team at the Energy and Bio-products Research Institute (EBRI), Aston University will screen three C4 – C5 bio-derived platform molecules4 as separate feedstocks to make propane and butane (bio-LPG) using their expertise in catalytic hydrothermal (hot-pressurised water) processing. Bio-derived molecules are obtained from aqueous fermentation broth and often require expensive water removal steps in order to get the pure product. The presence of water is an advantageous requirement during hydrothermal processing, meaning that there will be no need to dewater the feedstocks before they can be converted to bio-LPG. This will save cost as well. Therefore, if successful, results from this project will accelerate developing the process for large-scale production of bio-LPG – a complete biomass-derived drop-in fuel – to replace fossil-derived LPG for off-grid energy end users. This project has the potential to bring together experts in bio-catalysis and chemo-catalysis through BBSRC and EPSRC to solve a real industrial challenge in the near-term.
 Grand View Research, 2016. LPG Market Analysis by Source.  LGUK, 2020. About Liquefied Gas UK.  E. Johnson. 2019. Process Technologies and Projects for BioLPG. Energies.; 12(2), 250.  Sun et al., 2016. Production of C4 and C5 alcohols from biomass-derived materials. Green Chem., 2016,18, 2579-2597.
To test the catalytic conversion of biomass-derived feedstocks to bio-LPG component gases (propane and butane) under hydrothermal conditions.
The work programme carried out in this 6-month project has helped to deliver the experimental proof of concept of making high yields of propane from biomass-derived C4-based feedstocks. Some excellent results of high selectivity of the catalytic reaction towards propane have been achieved in a batch reactor under moderate hydrothermal conditions (< 300°C). These results will help to move this research towards TRL 4, when a bench-scale continuous rig would be acquired and used to validate the technology, paving the way toward potential commercialisation. The PI and industrial partner are excited by the results as they continue their collaborations.
The project has been delivered at the level of confidence required by the industrial partner, who has provided additional funding to continue the research collaboration, while seeking opportunities for longer-term funding. A new researcher has been trained in the fast-growing field of hydrothermal technology, which may influence their future career.
Academic partner: Jude Onwudili, Aston University
Industrial partner: Keith Simons, Calor Gas Limited