High-quality liquid fuels are obtained from non-edible carbohydrates by energy-efficient processes. 2-Methylfuran, produced by hydrogenation of furfural, is converted into 6-alkyl undecanes in a catalytic solvent-free process (see scheme with 6-butylundecane). A diesel fuel is produced with an excellent motor cetane number (71) and pour point (−90 °C) and with global process conversions and selectivities close to 90 %.
DOI: 10.1039/C4CY00717D, Communication
A new integrated strategy for the synthesis of GVL from beechwood based on the use of 2-MeTHF and RANEY Ni is presented.
Valerio Molinari,a Markus Antoniettia and Davide Esposito*a
aMax-Planck-Institute of Colloids and Interfaces, Department of Colloid Chemistry, 14424 Potsdam, Germany
E-mail: firstname.lastname@example.org ;
Tel: (+49) 0331 567 9538
Catal. Sci. Technol., 2014,4, 3626-3630
|Patent Number:||US 8502001|
|Title:||Production of alcohol from carbonaceous feedstock|
|Inventor(s):||Daniel, Berian John; Gracey, Benjamin Patrick|
|Patent Assignee(s):||BP P.L.C., UK|
The invention relates to the process for conversion of ethanoic acid into ethanol characterized by the following steps, (a) introducing ethanoic acid and H2 into a primary hydrogenation unit in the presence of a precious metal-based catalyst to produce ethanol and Et ethanoate, (b) introducing Et ethanoate, from step (a), together with H2, into a secondary hydrogenation unit in the presence of a copper-based catalyst to produce ethanol, and (c) recovering ethanol from step (b). Thus, in the primary reactor H2 and ethanoic acid with a molar ratio of 10/1 was passed over the palladium-silver-rhenium-iron catalyst at 230° and 2.0 MPa with a GHSV of 4343 h-1 to give a product showing conversion of ethanoic acid to Et groups recoverable as ethanol was 41.9 %, of which 19.7 % was as Et ethanoate, 21.6 % ethanol, 0.4 % ethanal and 0.2 % di-Et ether and the total conversion of ethanoic acid to products was 44.7 %, the selectivity of ethanoic acid to Et groups recoverable as ethanol was 93.8 %; in the secondary reactor H2 and Et ethanoate with a molar ratio of 10/1 was passed over the copper-based catalyst at 200° and 5.0 MPa with a GHSV of 4491 h-1, the conversion of Et ethanoate to Etgroups recoverable as ethanol was 69.5 %, the selectivity of Et ethanoate to Et groups recoverable as ethanol was 99.9%.
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As bioethanol continues to be an important component of gasoline, a high–carbon efficiency, nonfermentative route becomes increasingly important. One idea under exploration is gasifying cellulosic feedstocks to biosynthesis gas (syngas) and then converting the gas to mixed alcohols. The second step, however, is problematic because the initial formation of methanol is equilibrium-limited, and very high pressures are required to obtain even modest yields of C2+ alcohols.
Inventors B. J. Daniel and B. P. Gracey disclose a technique for making ethanol from syngas with high carbon efficiency. Methanol is first made from syngas by using conventional process technology. (Whether the syngas is biobased, natural gas–based, or coal-based is irrelevant.) The methanol is then carbonylated to acetic acid, again with conventional technology.
The patent’s invention is the hydrogenation of acetic acid (HOAc) to a mixture of ethanol (EtOH) and ethyl acetate (EtOAc). The EtOAc is separated and hydrogenated in another reactor to give additional EtOH.
In the patent’s one example, hydrogen and HOAc in a 10:1 mol ratio are passed over a Pd–Ag–Rh–Fe catalyst in the primary reactor at 230 ºC, 2.0 MPa pressure, and a gaseous hourly space velocity (GHSV) of 4343 h–1. The HOAc conversion is 41.9%, of which 19.7% is EtOAc, 21.6% EtOH, 0.4% MeCHO, and 0.2% Me2O. The overall selectivity to ethyl groups that can be recovered as EtOH is 93.8%.
In the secondary reactor, hydrogen and the EtOAc from the primary reactor in a 10:1 mol ratio are passed over a copper-based catalyst at 200 ºC, 5.0 MPa, and a GHSV of 4491h-1. The conversion of EtOAc is 69.5%, and the selectivity to ethyl groups that can be recovered as EtOH is 99.9%. Overall, the selectivity to EtOH is a high 95.7% (BP PLC [London]. US Patent 8,502,001, Aug 6, 2013; Jeffrey S. Plotkin)
Cocultures of microalgae and cyanobacteria show higher biomass production for biofuel than their monocultures
Lignocellulosic waste such as sawdust or straw can be used to produce biofuel — but only if the long cellulose and xylan chains can be successfully broken down into smaller sugar molecules. To do this, fungi are used which, by means of a specific chemical signal, can be made to produce the necessary enzymes. Scientist have now genetically modified fungi in order to make biofuel production significantly cheaper.
June 3, 2013 — Lignocellulosic waste such as sawdust or straw can be used to produce biofuel — but only if the long cellulose and xylan chains can be successfully broken down into smaller sugar molecules. To do this, fungi are used which, by means of a specific chemical signal, can be made to produce the necessary enzymes. Because this procedure is, however, very expensive, Vienna University of Technology has been investigating the molecular switch that regulates enzyme production in the fungus. As a result, it is now possible to manufacture genetically modified fungi that produce the necessary enzymes fully independently, thus making biofuel production significantly cheaper.
In the search for renewable alternatives to gasoline, heavy alcohols such as isobutanol are promising candidates. Not only do they contain more energy than ethanol, but they are also more compatible with existing gasoline-based infrastructure. For isobutanol to become practical, however, scientists need a way to reliably produce huge quantities of it from renewable sources.
MIT chemical engineers and biologists have now devised a way to dramatically boost isobutanol production in yeast, which naturally make it in small amounts. They engineered yeast so that isobutanol synthesis takes place entirely within mitochondria, cell structures that generate energy and also host many biosynthetic pathways. Using this approach, they were able to boost isobutanol production by about 260 percent.
Though still short of the scale needed for industrial production, the advance suggests that this is a promising approach to engineering not only isobutanol but other useful chemicals as well, says Gregory Stephanopoulos, an MIT professor of chemical engineering and one of the senior authors of a paper describing the work in the Feb. 17 online edition of Nature Biotechnology.
“It’s not specific to isobutanol,” Stephanopoulos says. “It’s opening up the opportunity to make a lot of biochemicals inside an organelle that may be much better suited for this purpose compared to the cytosol of the yeast cells.”
Stephanopoulos collaborated with Gerald Fink, an MIT professor of biology and member of the Whitehead Institute, on this research. The lead author of the paper is Jose Avalos, a postdoc at the Whitehead Institute and MIT.
Historically, researchers have tried to decrease isobutanol production in yeast, because it can ruin the flavor of wine and beer. However, “now there’s been a push to try to make it for fuel and other chemical purposes,” says Avalos, the paper’s lead author.
Yeast typically produce isobutanol in a series of reactions that take place in two different cell locations. The synthesis begins with pyruvate, a plentiful molecule generated by the breakdown of sugars such as glucose. Pyruvate is transported into the mitochondria, where it can enter many different metabolic pathways, including one that results in production of valine, an amino acid. Alpha-ketoisovalerate (alpha-KIV), a precursor in the valine and isobutanol biosynthetic pathways, is made in the mitochondria in the first phase of isobutanol production.
Valine and alpha-KIV can be transported out to the cytoplasm, where they are converted by a set of enzymes into isobutanol. Other researchers have tried to express all the enzymes needed for isobutanol biosynthesis in the cytoplasm. However, it’s difficult to get some of those enzymes to function in the cytoplasm as well as they do in the mitochondria.
The MIT researchers took the opposite approach: They moved the second phase, which naturally occurs in the cytoplasm, into the mitochondria. They achieved this by engineering the metabolic pathway’s enzymes to express a tag normally found on a mitochondrial protein, directing the cell to send them into the mitochondria.
This enzyme relocation boosted the production of isobutanol by 260 percent, and yields of two related alcohols, isopentanol and 2-methyl-1-butanol, went up even more — 370 and 500 percent, respectively.
There are likely several explanations for the dramatic increase, the researchers say. One strong possibility, though difficult to prove experimentally, is that clustering the enzymes together makes it more likely that the reactions will occur, Avalos says.
Another possible explanation is that moving the second half of the pathway into the mitochondria makes it easier for the enzymes to snatch up the limited supply of precursors before they can enter another metabolic pathway.
“Enzymes from the second phase, which are naturally out here in the cytoplasm, have to wait to see what comes out of the mitochondria and try to transform that. But when you bring them into the mitochondria, they’re better at competing with the pathways in there,” Avalos says.
The findings could have many applications in metabolic engineering. There are many situations where it could be advantageous to confine all of the steps of a reaction in a small space, which may not only boost efficiency but also prevent harmful intermediates from drifting away and damaging the cell.
The researchers are now trying to further boost isobutanol yields and reduce production of ethanol, which is still the major product of sugar breakdown in yeast.
“Knocking out the ethanol pathway is an important step in making this yeast suitable for production of isobutanol,” Stephanopoulos says. “Then we need to introduce isobutanol synthesis, replacing one with the other, to maintain everything balanced within the cell.”
The research was funded by the National Institutes of Health and Shell Global Solutions.