Sustainable aviation fuel from prehydrolysis liquors

Maximizing products of high value and minimizing incineration of side-streams is key to realize future biorefineries. In current textile production from forestry, hemicellulose is removed by prehydrolysis before delignification. The resulting prehydrolysis liquor is incinerated in the recovery boiler at low efficiency. This additional burden on the limiting recovery boiler reduces the pulp production. In this study, we demonstrate that prehydrolysis liquor can be upgraded, in 5 steps, to yield aviation fuels. Prehydrolysis liquors were dehydrated to furfural by zeolite catalysis. Furfural was selectively reduced to furfuryl alcohol by Au@NC. Rhenium-catalysed Achmatowicz rearrangement gave a C 5 intermediate susceptible to self [2 + 2] cycloaddition to give the C 10 oxygenated precursor. By using a combination of Ru/C and zeolites, full hydrodeoxygenation was achieved. The overall transformation from furfural to hydrocarbons resulted in a 48% carbon yield. The resulting hydrocarbons, containing an anticipated strained four-membered ring, are preferred aviation fuel components. This is an important step to show that aviation fuels can be produced sustainably from existing industrial side-streams. A comparative life cycle assessment was applied to evaluate the environmental impact of the proposed valorization approach, demonstrating benefits in the climate change impact category when implementing this technology in a pulp mill compared to the incineration of pre-hydrolysis liquor scenario. Maximizing products of high value and minimizing incineration of side-streams is key to realize future biorefineries.