## DoD Researchers Work to Increase the Production of Higher Chain Hydrocarbons from CO2 Using a Traditional Fischer-Tropsch Catalyst

##### 27 June 2009

Researchers at the US Naval Research Laboratory (NRL) and the Center for Applied Energy Research at the University of Kentucky are investigating the hydrogenation of CO2 using a conventional Fischer-Tropsch cobalt catalyst for the production of valuable hydrocarbon materials.

Other studies have shown the ability to convert CO2 primarily to methane with a distribution of other hydrocarbons (earlier post as one example). The focus of this work, reported online 25 June in the ACS journal Energy & Fuels, is to attempt to improve the production distribution toward higher chain hydrocarbons (HCs) and increase conversion rates using conventional Fischer-Tropsch catalysts (Co-Pt/Al2O3).

The US Department of Defense (DoD) is the single largest buyer and consumer of fuel at 12.6 million barrels per day, according to the Defense Energy Support Center.

World-wide “peak oil” production is expected to occur from 2010 to 2025+ (by some experts estimate that we have already reached peak production since 2004). This along with increasing demand can cause large swings in price and availability. Fuel independence would alleviate uncertainties in the world market supply of oil along with commercial fluctuations in price.

In addition only high energy density petroleum-derived fuel meets stringent military aviation requirements. Thus, the DOD has a vested interest in maintaining this supply by supporting the development of synthetic hydrocarbon fuel from the vast natural resources, such as coal, shale, gas hydrates, and CO2, available in the United States.

—Dorner et al. (2009)

Very little research has been performed applying CO2 as the carbon source in synthetic fuel production, the authors note, because generally CO2—which is chemically very stable—has been thought of as having too high of an energy barrier for polymerization, even in the presence of a catalyst.

The problem with conventional Fischer-Tropsch processes for the production of synfuels is their carbon intensity, and their being practical only for “land-based operations.” NRL is eyeing the concentration of CO2 in the ocean (“relatively concentrated at approximately 100 mg/L of seawater“) as a potential source.

...if CO2 could economically be extracted from the ocean, then marine engineering processes could be envisioned to use this carbon source as a potential chemical feedstock. From an environmental perspective, such a process would have tremendous benefits in reducing the impact of anthropogenic CO2 on climate change and would eliminate the emission of sulfur and nitrogen compounds that are readily produced from the combustion of petroleum-derived fuels.

—Dorner et al. (2009)

The researchers conducted the CO2 hydrogenation reactions in a one-liter three-phase slurry continuously stirred tank reactor. The team measured the ability to direct product distribution as a function of different feed gas ratios of H2 and CO2 (3:1, 2:1, and 1:1) as well as operating pressures ranging from 450 to 150 psig.

Under all conditions investigated, methane remains the primary product, with concentrations ranging from 97.6% of the product to 93.1%; higher concentrations of C2-C4 hydrocarbons were found at the 1:1 ratio. The researchers also found that the portion of longer chain hydrocarbons (i.e., hydrocarbons above methane) increases with increasing time on stream (TOS), irrespective of the H2/CO2 ratio.

The authors suggest that deactivation of the methane-forming active sites on the catalyst with increasing TOS may play a role in this product distribution shift toward C2-C4 HC with increasing TOS, irrespective of the feed gas ratio. They also speculate that the change in the feed gas ratio leads to a lowering of the catalyst’s methanation ability of CO2 in favor of chain growth, with two different active sites for methane and C2-C4 products present on the surface of the catalyst.

Future research will focus on determining the proposed reaction mechanism and corroborating the hypotheses.

Resources

• Robert W. Dorner, Dennis R. Hardy, Frederick W. Williams, Burtron H. Davis and Heather D. Willauer (2009) Influence of Gas Feed Composition and Pressure on the Catalytic Conversion of CO2 to Hydrocarbons Using a Traditional Cobalt-Based Fischer-Tropsch Catalyst. Energy Fuels, Article ASAP doi: 10.1021/ef900275m

Fascinating research...maybe they can figure out a way to get the CO2 they need from power plants?

"...if CO2 could economically be extracted from the ocean..."

You have plenty that you could get from IGCC plants, where you want to sequester it. You can also get it from ethanol plants rather than vent it to the atmosphere.

If they could find a way to turn CO2 into fuel, it would change the situation at hand. Now you can get something for the CO2 produced and in the case of cellulose ethanol with fermentation, it is CO2 neutral.

You still need to add all the energy-content you will produce by adding H2. Though, it would be great if off-peak cheap electricity could be used to produce H2 and thus liquid fuels. CO2 can be stored and transported easily ; H2 can be produced anywhere using electricity.

I suppose the army will use nuclear energy to produce liquid fuels at sea.

More likely the Navy will set up a compact seawater to Jet A4 refinery on an aircraft carrier (already nuclear powered) and only cruise the seven seas at 1/2 speed, but still run the reactor flat out.
The excess power can be diverted to make H2 and by extracting CO2 from seawater they can crusie any where they wish for as long as they like.
Velocys has done a huge amount of work on compact microchannel reactors for FT.
My back of the envelope calcs suggest 20 MW of electric power would make around 1500 gallons jet fuel / day.

SVW: If they are successful you'd think they'd want to scale up the process to the maximum extent possible and minimizing regulatory oversight. The Navy could build it's own nuclear powered supertankers - load up at sea, offload at port (and create jobs jobs jobs in the process of building the new ships). They could also build some kind of smaller nuclear powered refining ship & pipe the fuel to nearby tankers....or perhaps it doesn't even have to be nuclear powered - maybe self-sustaining at some point. However the minute you start talking about pipelines on the sea floor & massive sea-based refining operations the red tape increases exponentially...many small simplified operations are better than a few complex big ones.

No way. Oil&gas are fossil fuels. Synthesis of oil and methane from simple molecules is impossible.

Get your facts straight, clearly it's not impossible if plants can do it. However it does take a lot of energy.

Canadian Athabasca region tar sands contain more oil than the whole world conventional oil reserves. However, such oil reserves is only 1/10 of original oil deposits; the rest 9/10 were destroyed over the eons by wash-out and microbial degradation.

These are the facts. And some interesting things are quite revealing from such facts:

1. Oxidation of 10 times of current known oil reserves did not lead to global climate catastrophe.
2. There is no way such massive local oil reserves were formed from tissue of dead animals or plants.
3. As it is proved by massive oil findings in Western Siberia, off-shore Brazil, Mexican gulf, and Black Sea, most of Earth oil were formed by abiotic synthesis in Earth mantle, not by transform of deposits of dead organics.
4. Current described in the article findings actually prove that high hydrocarbons could be easily formed from CO2 bearing feedstock under high pressure and high temperature of upper Earth mantle.
5. [deleted]

[Ed. note: Commenter has been banned due to inappropriate language in comment #5.]

"Oxidation of 10 times of current known oil reserves did not lead to global climate catastrophe."

Well it wouldn't would it? Not if it were oxidized over 'the EONS' and thus giving the living plants enough time to take it back out of the atmosphere. Our current "global climate catastrophe" is not a result of our burning the remaining fossil fuels. It is the result of our burning the remaining fossil fuels in a few short decades while stifling the growth of the world's biosphere with our pollution, suburban sprawl, intensive monoculture farming, deforestation and ocean fisheries strip mining! [to name a few]

As for the rest of your post - somewhere in the background the theme music from 'The Twilight Zone' is playing.

"Peak oilers are better suck their own dicks."
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Are you saying because there's lots of Canadian Tar sands that we have tons of oil? If so, you have a lot to learn about the process of making Tar Sands usable.

Andrey,

I think that last comment qualifies you for a permanent banning. I will email Mike now.

Numerous studies suggest fuel delivered to an active theater of war costs up to $200 / gallon. The exact number isn't the issue, something like 80% of fuel needed is consumed in the delivery process itself and also the majority of casualties sustained. Just what kind of cost, logistics and personal are involved to protect a refueling tanker in the Straits of Hormuz? Not only do you have the tankers fuel use, but the destroyers in convoy to protect it, the airplanes that give air cover, and all the military personal. Even if 20MW needed to make only 1500 gallon per day this probably costs less than$20 gallon......

Great potential.
I made a small calculation. If one single 5MW windturbine produces an average output of 1.5MW and this is converted with a 50% efficiency to H2 and thus liquid fuel via this catalyst, that makes 700 tons of fuel/year. That's about the amount produced by 14 hectares of algae (both need a concentrated CO2 source) or 50 hectares of switchgrass...

If the CO2 feedstock is not taken from the air this process amounts to little more than a technical stunt. If it uses CO2 captured from coal-burning power plants it would be virtually useless in reducing global warming, regardless of the power source used to run the process. The use of coal as fuel in any form will be essentially banned worldwide within about 25 years, so time and money invested in new technologies that depend on burning coal are wasted.

I don't get the emphasis on getting CO2 from the water, unless the point of the research is to use nuclear power (like from an aircraft carrier) to produce the jet fuel needed by its own aircraft.

Richard,

I am not sure that I understand. I thought the ocean was the largest CO2 sink on the plant. It would seem that Air->Ocean+energy->fuel->Air is a valid sustainable cycle. The two issues that I see are: Where does the energy come from? How fast does the ocean capture CO2 and is this faster than the proposed method of extraction?

Let's see, you have CO2 from a coal plant AND CO2 from gasoline, but now you use the CO2 from the coal to make liquid fuel. It seems like you are not emitting the CO2 from the gasoline and using the CO2 from the coal twice before it goes to the atmosphere. That seems like a reduction to me.

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