A process was developed for converting alcohol sourced from renewable or industrial waste gases into jet or diesel fuel. Two key technologies power the energy-efficient fuel production units. A single-step chemical conversion streamlines what is currently a multi-step process. The catalyst converts biofuel (ethanol) directly into a versatile “platform” chemical called n-butene. A microchannel reactor design further reduces costs while delivering a scalable modular processing system.
The process would provide a more efficient route for converting renewable and waste-derived ethanol to useful chemicals. Currently, n-butene is produced from fossil-based feedstocks using the energy-intensive cracking — or breaking down — of large molecules. The new technology reduces emissions of carbon dioxide by using renewable or recycled carbon feedstocks. Using sustainably derived n-butene as a starting point, existing processes can further refine the chemical for multiple commercial uses, including diesel and jet fuels, and industrial lubricants.
The chemical conversion process is being integrated into microchannel reactors built using newly developed 3D printing technology. Also called additive manufacturing, 3D printing allows the research team to create a pleated honeycomb of mini-reactors that greatly increase the effective surface-area-to-volume ratio available for the reaction.
When ethanol is passed over a solid silver-zirconia-based catalyst supported on a silica, it performs the essential chemical reactions that convert ethanol to either n-butene or, with some modifications to the reaction conditions, butadiene. After prolonged-duration studies, the catalyst remains stable. The research team showed that if the catalyst loses activity, it can be regenerated by a simple procedure to remove coke — a hard carbon-based coating that can build up over time. An even more efficient, updated catalyst formulation will be used for scale up.
By adjusting the pressure and other variables, the team can also tune the system to generate either butadiene, a building block for synthetic plastic or rubber, or an n-butene, which is suitable for making jet fuels or products such as synthetic lubricant.