UC Davis process produces gasoline-range hydrocarbons from biomass-derived levulinic acid; field-to-tank yield of >60% claimed
|GC-MS chromatogram of the liquid products obtained after hydrodeoxygenation of angelica lactone dimer. Source: Mascal et al. SI. Click to enlarge.|
Researchers at the University of California, Davis have developed a process for the production of branched C7–C10 hydrocarbons in the gasoline volatility range from biomass-derived levulinic acid with good yield, operating under relatively mild conditions, with short reaction times.
Considering that levulinic acid is available with more than 80% conversion from raw biomass, a field-to-tank yield of drop-in, cellulosic gasoline of more than 60% is possible, the researchers claimed. A paper on their work is published in the journal Angewandte Chemie International Edition; UC Davis has filed provisional patents on the process, and is making it available for licensing.
|As a very rough benchmark on yield, cellulosic gasoline and diesel company KiOR, which uses a different pathway for fuel production (the production of renewable crude from biomass followed by catalytic cracking to upgrade to fuels), calculates that one bone dry ton of woody biomass contains hydrocarbons approximately equal to 2.8 barrels of oil (117.6 gallons US).|
|As noted in its quarterly report (10-Q) for the quarter ending 30 September 2013, KiOR had obtained a yield of 72 gallons per bone dry ton (about 41% gasoline, 37% diesel, 22% fuel oil) for between $2.60 and $2.80 per gallon.|
|Its long term target is 92 gallons/BDT. KiOR has halted commercial production this year in order to tune up its yield and tune down its costs. (Earlier post.)|
The process dehydrates the biomass-derived levulinic acid under solid acid catalysis and then treats the resulting angelica lactone with catalytic K2CO3, producing the angelica lactone dimer (ALD). This dimer, in turn, serves as the feedstock for hydrodeoxygenation, which proceeds under relatively mild conditions with a combination of oxophilic metal and noble metal catalysts to yield the branched hydrocarbons in the gasoline range.
Traditional diesel fuel is made up of long, straight chains of carbon atoms, while the molecules that make up gasoline are shorter and branched. Biodiesel, refined from plant-based oils, is already commercially available to run modified diesel engines. A plant-based gasoline replacement would open up a much bigger market for renewable fuels.
The levulinic acid feedstock for the new process can be produced by chemical processing of materials such as straw, corn stalks or even municipal green waste. It’s a cheap and practical starting point that can be produced from raw biomass with high yield, Mascal said.
Because the process does not rely on fermentation, the cellulose does not have to be converted to sugars first. Coauthors on the paper are postdoctoral researchers Saikat Dutta and Inaki Gandarias.
Prof. Mark Mascal, Dr. Saikat Dutta, Dr. Inaki Gandarias (2014) “Hydrodeoxygenation of the Angelica Lactone Dimer, a Cellulose-Based Feedstock: Simple, High-Yield Synthesis of Branched C7–C10 Gasoline-like Hydrocarbons,” Angewandte Chemie International Editiondoi: 10.1002/anie.201308143