Novel composite catalyst holds promise for cost-effective ethanol-to-jet-fuel conversion

Decarbonizing air transportation is critical to meeting U.S. climate goals and improving the nation’s energy economy. But technologies that are transforming automobiles – such as electric motors and hydrogen fuels – are difficult to implement in aircraft.

A battery powerful enough to fuel an airplane would be prohibitively heavy. Hydrogen is only one quarter as energy dense as jet fuel (and many times more expensive) but would require large complex storage tanks onboard. To greatly reduce its emissions, the U.S. commercial aviation sector will need new methods of making sustainable aviation fuel.

The well-established, cost-competitive ethanol market provides an opportunity to shift the composition of jet fuel and other fuel products away from petroleum. The Department of Energy’s Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office is focused on developing industrially viable fuels using renewable biomass, including national laboratory efforts to produce drop-in biofuels compatible with current aircraft systems.

In the first step of a multi-step ethanol-to-jet-fuel process developed by DOE’s Oak Ridge National Laboratory, a catalyst is used to convert ethanol into butene-rich C3+ olefins, important intermediates that can then be processed into aviation fuels. Two more steps — oligomerization and hydrotreating — convert these intermediates into the liquid hydrocarbons used as fuels.

ORNL’s Zhenglong Li led a team tasked with improving the current technique for converting ethanol to C3+ olefins and demonstrated a unique composite catalyst that upends current practice and drives down costs. The research was published in ACS Catalysis.