Hydrogen can be a zero-emissions fuel source, but its storage and transportation are costly and problematic, limiting its widespread use. Liquid organic hydrogen carriers (LOHCs), in which hydrogen atoms are chemically bound to liquid hydrocarbons via reversible hydrogenation reactions, offer a strategy for high-density storage and straightforward storage and transport.
A team of researchers from Washington State University (WSU; Richland, Wash.; www.wsu.edu) and Pacific Northwest National Laboratory (PNNL; Richland, Wash.; www.pnnl.gov) demonstrated the use of a lignin-based jet fuel as a new LOHC. The team, led by WSU engineer Bin Yang, had previously developed lignin-based jet fuel (LJF) with a process that converts lignin from waste biomass into primarily cycloalkane hydrocarbons, including alkyl-substituted mono-, bi-, and tri-cyclohexyl alkanes that can be used in jet fuel formulations.
Now, using platinum nanoparticles supported on zeolite (aluminosilicate compounds) as catalysts, the lignin jet fuel can undergo a dehydrogenation process that forms aromatic species, including alkylbenzenes, tetralins and naphthalenes. The dehydrogenated LJF, known as LJF-HyC, can then serve as a potential liquid hydrogen storage medium. In the study, researchers found the dehydrogenation of LJF into LJF-HyC “revealed a significant presence of aromatic species, comprising approximately 18.5 wt.% of the dehydrogenated LJF.”
Once the hydrogen carrier is made, it can be hydrogenated to store and transport hydrogen, and would be released at a point of use with another similar catalytic process. Using the LJF as a LOHC facilitates efficient high-density hydrogen storage in an easy-to-handle sustainable aviation fuel (SAF), the researchers say. “This approach offers promising opportunities for compatibility with existing infrastructure, economic viability for scalable production, and creates a synergistic system that enhances the efficiency, safety and sustainability of both SAF and hydrogen technologies,” they wrote in a recent publication of the work in the International Journal of Hydrogen Energy. The researchers are now working on methods to reduce the cost of the catalyst manufacturing.