Chevron’s division Chevron Technology Ventures (CTV) and Mascoma Corporation have come to a feedstock processing and lignin supply agreement. In the deal CTV will provide various sources of lignocellulosic feedstock to Mascoma, which will then convert the feedstock to cellulosic ethanol through its proprietary process, which produces lignin as a by-product.

Now it gets interesting. Mascoma will be returning the lignin back to CTV for evaluation.

CTV is developing proprietary technology and catalysts for the conversion of lignin into hydrocarbon components for transportation fuels. Chevron has filed applications for two patents on processes to convert lignin to a hydrocarbon feedstock via hydroprocessing; with both applications published on September 3rd, 2009.

Dr. Jim Flatt, Mascoma’s President says, “This is an important moment for us at Mascoma. The upgrading of our byproduct lignin to high value transportation fuels is an important step in our effort to prove the effectiveness of integrated biorefineries. It has been our goal all along to make our process as integrated and sustainable as possible.”

With the easy carbon out reformed back into ethanol through Mascoma’s proprietary Consolidated Bio Processing method, which breaks down the sugars in the cellulose and turns it into ethanol, the energy-rich lignin is left over.  Lignin is a complex chemical compound (a cross-linked amorphous phenolic polymer) and is the component of biomass with highest energy content, some 9,000 – 11,000 Btu/lb compared to 7,300 – 7,500 for cellulose, about 20% more.

So far lignin is not directly useful as a refinery feedstock for biofuels synthesis.  Being a phenolic, lignin is in a high oxidation state with a low energy content compared to common refinery fuels.  It is so highly oxygenated that it is not generally compatible with hydrocarbon streams as having all that oxygen in high temperature process streams isn’t good at all.

In February Chevron filed applications for two patents on refinery-based processes for converting lignin to hydrocarbon fuel components.  In one filing the lignin is first separated from the black liquor at a paper mill and then transported from the paper mill to the refinery for hydroprocessing. In the second, the entire black liquor solution may be transported from the paper mill to the refinery for hydroprocessing.  Its seems Chevron has learned something – the Mascoma agreement opens up the potential for another alternative source of lignin.

The patented processes significantly increase the energy content of the lignin and reduce the oxygen content. The basic steps are:

  • Lignin is introduced into a hydroprocessor. Hydroprocessing includes hydrocracking and hydrotreating—cracking the larger lignin molecules into smaller molecules—using a reductant and a catalyst at high temperature and pressure. Examples of hydroprocessing catalysts include molybdenum, cobalt, nickel, tungsten, iron and/or platinum on an amorphous or crystalline oxide matrix. Optionally a hydrocarbon solvent can also be added as a slurry for the catalyst.
  • After the introduction of the lignin and the catalyst into the hydroprocessor, the reductant is pressurized into the hydroprocessor. One example of a reductant for the hydroprocessor is hydrogen, which can be obtained from the same source providing hydrogen for other refinery processes. In addition, the reductant for the hydroprocessor could also be syngas. The presence of carbon monoxide in the syngas can assist with the conversion of lignin, and the observed effect is similar to that seen for coal hydroprocessing with syngas compared to hydrogen alone.
  • Unlike coal or heavy crude oil hydroprocessing, significant amounts of water are produced as a result of lignin hydroprocessing, due to the fact that lignin is oxygenated to a much greater degree than coal or heavy crude oil. Chevron says tests have shown that this produced water does not inhibit the lignin conversion. At the end of the reaction the water will condense and phase separate from the biofuels feedstock. The water extracts any residual salts that may be present in the lignin thereby preventing fouling or deactivation of the catalyst. After the separation from the water the biofuels feedstock will also be separated and filtered to remove the catalyst for recycling.
  • In an exemplary embodiment cited in the patent application, the hydroprocessing comprises activated slurry hydrocracking with a molybdenum sulfide heterogeneous catalyst at approximately 2000 psi with hydrogen for about six hours.
  • At the end of the reaction, the product is introduced into the refinery processes to produce a biofuel. The particular location of the introduction of the biofuels feedstock within the refinery processes will depend on the composition of the biofuels feedstock. The biofuels feedstock will be primarily a diesel-like stream.

Back in February of 2008, Chevron Corporation and Weyerhaeuser Company created a 50-50 joint venture company called Catchlight Energy LLC, which focused on developing the next generation of renewable transportation fuels from nonfood sources.  Catchlight’s initial focus is stated as developing and demonstrating novel technologies for converting cellulose and lignin into biofuels. Catchlight’s two main thrusts in its current research efforts are a near-term focus on early commercialization opportunities for producing ethanol and a longer-term focus on direct conversion of biomass to hydrocarbons.

Mascoma began in December of 2008 creating ethanol from cellulosic biomass with positive results at its demonstration facility in Rome, New York. The company, in collaboration with its commercialization subsidiary Frontier Renewable Resources, is in the process of financing its first full-scale ethanol facility in Kinross, Michigan. The company plans to break ground on that facility during the first half of 2010.

Several scenarios become objects for speculation on where the technology has gotten to and will be going.  With the ethanol already out and a process in hand for the lignin, Chevron has two of the major elements in a feedback loop from fuel to plants and back to fuel again.  That just leaves the cellulose to handle and wondering where the needed hydrogen is going to come from.

Things might be further along that are being said, covering a very wide array of prospective plants crops for production of fuels. It will be interesting to see what the economics turn out to be like in comparison to crude oil and if the processes can get to economic scale.


1 Comment so far

  1. Rosa Immerman on October 19, 2010 4:11 PM

    Nice information. I appreciate your effort, I look forward to reading more of your posts.

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