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Researchers demonstrate production of C3 hydrocarbons from biomass with no external H2 required

Researchers have demonstrated a route for the production of major commercial C3 hydrocarbons (propane and propylene) from renewable biomass via the hydrothermal conversion of well-known fermentation end-products (butyric acid and 3-hydroxybutyrate) without the use of exogenous hydrogen. The process can potentially have high thermal efficiencies.

The two-step process first uses fermentation to produce partially deoxygenated intermediate chemicals. These intermediate chemicals are subsequently decarboxylated and/or dehydrated in hydrothermal media to produce the C3 hydrocarbons.

A paper on their work appears in the ACS journal Industrial and Engineering Chemistry Research.

Specifically, the major commercial C3 hydrocarbons, propane and propylene, can be obtained from butyric acid and 3-hydroxybutyrate (3HB) in substantial yields and industrially relevant productivities by hydrothermal decarboxylation. Butyric acid decarboxylates in supercritical water to give propane as the major product at 454 °C and 25 MPa. 3HB undergoes joint dehydration and decarboxylation in subcritical water to yield propylene at 371 °C and 25 MPa with yields of up to 48 mol %.

Although catalysts may be found that increase yields and selectivities, these processes were demonstrated without any added heterogeneous catalysts, and have the further advantage of requiring no external H2 source.

—Fischer et al.

Authors Curt R. Fischer, Andrew A. Peterson, Jefferson W. Tester were originally at MIT; they are now at Ginkgo Bioworks, Stanford University, and Cornell University, respectively.


  • Curt R. Fischer, Andrew A. Peterson, Jefferson W. Tester (2011) Production of C3 Hydrocarbons from Biomass via Hydrothermal Carboxylate Reforming. Industrial & Engineering Chemistry doi: 10.1021/ie1023386



If you use oxygen for the gasification and hydrogen to increase yields, you can turn biomass into a lot of fuel. Solar thermal/electric can produce both more efficiently.


Hydrothermal decarboxylation is a great advance; it can probably be driven by solar heat, eliminating the need to burn feedstock for process heat. The questions I have (can't see the paper as it's behind a paywall):

  1. If the reaction yield is 48mol%, what are the other products vs. unreacted feedstock?
  2. What's the time required for the reaction?
  3. Are any solids or tars produced?
All of those are going to be factors in taking this from the lab to industrial scale.

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