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ACS Meeting Symposium Focuses on Conversion and Utilization of CO2 for Fuels and Chemicals

Researchers at the US Naval Research Laboratory (NRL) led off a day-long symposium on advances in CO2 conversion and utilization being held at the 238th American Chemical Society (ACS) national meeting, which began today in Washington, DC. The NRL researchers presented their progress in hydrogenating CO2 to jet fuel via a two-stage, high-yield and highly selective synthesis process. (Earlier post.)

Robert Dorner and his colleagues are looking at converting CO2 and hydrogen (both won from sea-water) over catalysts, using the CO2 as a building block to form synthetic fuel. This reaction is energetically not favored and thus a catalyst is needed, which will lower the energy barrier of the reaction and increase the rate at which it occurs. The energy utilized to convert CO2 and hydrogen is also harvested from the ocean, by taking advantage of the temperature gradient of the water with increasing depth, making the fuel CO2-neutral.

CO2 conversion to hydrocarbons over catalysts has been known for several decades but has been shown very little research and development attention, as other technologies have been much cheaper and efficient in yielding cheap oil. However, with the increasing awareness of the impact CO2 has on the environment more and more attention is being directed at how to mitigate the effects CO2 has as a greenhouse gas. Most research to date however is focusing on the sequestration of CO2 in underground reservoirs.

Our research proposes the utilization of CO2 into fuel, recycling the gas and using it as a raw material rather than a waste product. In light of dwindling oil resources and the looming presence of peak oil, alternative fuels that are environmentally friendly and enhance energy security are of mounting importance. Our research is aiming at increasing productivity and selectivity of the desired products formed; thus reducing unwanted side-products and lowering costs, making this technology more economically feasible.

—Robert Dorner

Initial tests were performed on a Co/Pt/Al2O3 catalyst under several experimental conditions (varying CO2:H2 ratios and pressure). This catalyst converts the feed gas predominantly to methane under all conditions (ca. 95%). Iron-based catalysts however show a much improved water-gas-shift and CO2 hydrogenation ability, mainly yielding short-chain hydrocarbons, and thus making them superior to the Co-based catalysts.

The in-situ reduction environment of the iron catalyst plays a pivotal role in the products formed, with chain-growth only achieved at higher activation temperatures. The product distribution over this iron catalyst shows a clear ability to convert CO2 to longer chain hydrocarbons (especially olefins), with methane selectivity of only around 30%.

Fe-catalysts therefore lend themselves well to achieve the research objective—synthesizing unsaturated, short-chain hydrocarbons that can be oligomerized to jet fuel, with the help of a second solid acid catalyst, such as zeolites. The Fe-catalyst’s ability to form olefins is tailored by the addition of co-catalysts (such as Mn) at varying loadings, while alternative supports are also investigated to increase CO2 conversion.

—Robert Dorner

The electrochemical reduction of carbon dioxide. The NRL work was followed by a presentation of work being done at the University of Liverpool (UK) on the electrochemical reduction of CO2, focused on surface structures of copper electrodes and the role of solution-based copper species for their catalytic effect on the reaction.

The scientific community has known for several decades the ability of certain metals, particularly copper, to convert carbon dioxide into small organic molecules by using electricity as an energy source. This conversion of carbon dioxide occurs only at the interface between the metal surface and carbon dioxide gas. Studying such interfaces is challenging and presents novel research opportunities because the region where the chemistry occurs is of only nanometer dimensions, and therefore identifying specific reactions is like searching for a needle in a very large haystack.

Our work is unique in that we are creating highly controlled reaction environments and using advanced spectroscopic techniques that could, in the needle-in-haystack analogy, provide us an extremely powerful metal detector. This provides an excellent opportunity to study exactly how carbon dioxide transforms into useful, carbon-based, products.

—Scott Shaw

The University of Liverpool work received support from the European Union ELCAT (Electrocatalytic gas-phase conversion of CO2 in confined catalysts) project. (Earlier post.)

Other papers presented in the symposium included:

  • Methane-carbon dioxide reforming over Ni/CaO-ZrO2 catalyst. Researchers from the Chinese Academy of Sciences are investigating the carbon dioxide reforming of methane over an Ni/CaO-ZrO2 catalyst derived from co-precipitation method. The catalyst shows both high catalytic activity and stability at the methane and carbon dioxide ratio of 1:1. The characterization confirms that the nano-porous framework of as-prepared support together with the Ni-support interaction enhances the dispersion of Ni, and then promotes the resistance to sintering under reaction condition. As a result, carbon deposition is prevented, which is important for the catalyst stability.

  • Ni-based nanocomposite catalysts for energy-saving syngas and hydrogen production from CH4/CO2 and CH4/CO2/H2O. Researchers from Tsinghua University (China) are investigating energy-saving catalysts for natural gas conversion. They developed nanostructured Ni-oxide (oxide = ZrO2, MgO and Al2O3) catalysts as nanocomposites consisting of comparably sized metallic Ni nanocrystals and nanoparticles of “support” oxides. Compared with the conventional oxide-supported Ni catalysts, the nanocomposite catalysts are found extremely stable in catalyzing the methane reforming reactions using stoichiometric CO2 and methane as well as steam (H2O) and methane.

    The nanocomposite catalysts also show stable catalysis for a combined steam and CO2 reforming of methane under stoichiometric feed compositions, enabling modulation of product syngas molar ratios (H2/CO = 1.0~3.0) by varying the feed H2O/CO2 ratio. Further tests of nanocomposite Ni-ZrO2 and Ni-MgO catalysts for hydrogen generation by stepwised methane reforming processes, involving a catalytic methane decomposition to produce pure hydrogen and carbon deposits as the first step (step-I) and a volatilization of the carbon deposits by steam or CO2 as the second step (step-II) demonstrate that the nanocomposite catalysts are optimistic for energy-saving in methane reforming technologies.

  • Photoreduction of CO2 to CO in the presence of H2 over various basic metal oxide photocatalysts. Researchers at Kyoto University (Japan) are exploring the chemical fixation of CO2 in the presence of a heterogeneous photocatalyst as a method for converting it into other carbon sources such as carbon monoxide (CO), formaldehyde (HCHO), formic acid (HCOOH), methanol (CH3OH), and methane (CH4).

    The researchers have reported the photoreduction of CO2 to CO as the product over Rh/TiO2 and basic metal oxides such as ZrO2, MgO and Ga2O3 in the presence of H2 as the reductant. In addition, it has been found that CO is formed as a result of the photoreduction of CO2 in the presence of CH4 as a substitute for H2 over ZrO2 and MgO. In this study, they reported that various metal oxides exhibit the photocatalytic activity for the photoreduction of CO2 in the presence of H2.

  • Synthesis and characterization of ferrite materials for thermochemical CO2 splitting using concentrated solar energy. Researchers at Sandia National Laboratories are investigating the use of concentrated solar power to convert carbon dioxide and water to precursors for liquid hydrocarbon fuels (Sunshine to Petrol) using concentrated solar power. (Earlier post.)

    The researchers note that significant advances have been made in the field of solar thermochemical CO2-splitting technologies utilizing yttria-stabilized zirconia (YSZ)-supported ferrite composites. Such materials work via the basic redox reactions:

    Fe3O4 → 3FeO + ½O2      (Thermal reduction, >1350 °C)

    3FeO + CO2 → Fe3O4 + CO     (CO2-splitting oxidation, <1200 °C)

    The Sandia team has a systematic study underway of the ferrite-based materials at the high temperatures and conditions present in these cycles. At the ACS meeting, they discussed the synthesis, structural characterization (including scanning electron microscopy and room temperature and in-situ x-ray diffraction), and thermogravimetric analysis of YSZ-supported ferrites.

  • CO2 splitting via two-step solar thermochemical cycles via metal oxide redox reactions: Thermodynamic and kinetic analyses. Researchers from the Paul Scherrer Institute and ETH - Swiss Federal Institute of Technology are using concentrated solar energy as the source of high-temperature process heat in a two-step CO2 splitting cycle based on Zn/ZnO redox reactions to produce renewable carbon-neutral fuels.

    The solar thermochemical cycle consists of:

    1. the solar endothermic dissociation of ZnO to Zn and O2;
    2. a non-solar exothermic reduction of CO2 with Zn to CO and ZnO; the latter is the recycled to first 1st solar step.
    The net reaction is CO2 = CO + ½O2, with products formed in different steps, thereby eliminating the need for their separation.

    A Second-Law thermodynamic analysis indicates a maximum solar-to-chemical energy conversion efficiency of 39% for a solar concentration ratio of 5000 suns. The technical feasibility of the first step of the cycle has been demonstrated in a solar furnace with a 10 kW solar reactor prototype. The team experimentally investigated the second step of the cycle in a vertical quartz aerosol reactor, designed for in-situ quenching of Zn vapor, formation of Zn nanoparticles, and oxidation with CO2. They obtained CO2 conversions of up to 45% are obtained for a residence time of ~ 1 s.

  • Conversion of CO2 into methanol in a novel two-stage catalyst bed concept. Researchers from Shiraz University (Iran) are investigating a two-stage catalyst bed concept for conversion of CO2 to methanol.

    In the first catalyst bed, synthesis gas is partly converted to methanol in a conventional water-cooled reactor. This bed operates at higher than normal operating temperature and at high yield. In the second bed, the reaction heat is used to pre-heat the feed gas to the first bed. The continuously reduced temperature in this bed provides increasing thermodynamic equilibrium potential. In this bed, the reaction rate is much lower and, consequently, so is the amount of the reaction heat.

    This feature results in milder temperature profiles in the second bed because less heat is liberated compared to the first bed. In this way the catalysts are exposed to less extreme temperatures and, catalyst deactivation via sintering is circumvented.

    The researchers presented a one-dimensional dynamic plug flow dynamic used to analyze and compare the performance of two-stage bed and conventional single bed reactors. The results of this work show that the two-stage catalyst bed system can be operated with higher conversion and longer catalyst lifetime.

A number of other papers presented during the symposium focused on novel methods for carbon dioxide capture or adsorption of CO2 on a catalyst as a key step of the catalytic conversion of CO2 to liquid fuels.


Henry Gibson

There are many former oil producing areas in the US where CO2 will actually instantly restart the production of oil or increase the production of oil if injected in large quantities. This is the quickest way to produce oil with CO2. Perhaps the need is not for a national electrical grid but for a grid of buried CO2 pipelines. In buried pipelines, CO2 can be kept liquid at pressures well below current pipeline standards.

There is a recent conversion of an old oil pipeline in Holland to a CO2 pipeline that is used to carry CO2 to an area with many greenhouse growing facities.

There is also a pipeline to carry CO2 from a coal processing facility in North Dakota to oilfields in Canada. This CO2 is very successfully used to maintain oil production in the fields.

It is possible that under some conditions CO2 will displace very much more of the oil in oil deposits. Liquid CO2 and super-critical CO2 may have a very interesting effect in dissolving the oil, and when mixed with water, CO2 can dissolve many rocks that contain calcium or magnesium or both.

In coal mines CO2 can release methane from the coal structure before the coal is mined to gain fuel and to eliminate the release of much methane during mining.

To have massive amounts of CO2 available in pipe lines and stored in former oilfields can make the fighting of fires in cities less damaging and perhaps be used for other fires.

As is demonstrated by solar cells but not well understood by the general populace, the pice of the equipment needed to collect solar or any other forms of energy has more to do with the cost of that energy.

What most people forget is that, in the long run, coal and oil are renewable energy. The solar system provided the energy in coal and oil deposits free for the taking and has been doing so for billions of years; just as the solar system has been providing heat and light in those past years and recent years. Solar, hydro, wind and wave energy are all from past and present heat and light from the sun.

Geothermal energy is likely from atomic disintegration of mostly thorium and uranium inside the earth. There may be great amounts of these very heavy metals near the center of the earth because they are far heavier than iron.

At one time there may have been a fission reactor at the center of the earth billions of years ago when there was much more of the easily fissionable isotope of uranium available. It is known that there were natural fission reactors in the uranium ore beds of Africa that operated intermittently for millions of years many millions of years ago.

It is a known, relatively simple set of processes to convert CO2 and hydrogen to methanol, a fuel that is suitable for almost all earth bound needs of liquid fuels.

CO2 and H2 can be combined to make H20 and CO, and CO and H2 can be fed to fermentors to make ethanol. If they can be fed to fermentors to make n-Butanol then even aircraft can use it as an efficient fuel. N-Butanol is nearly a direct substitute for gasoline in many automobiles and trucks.

Electrolytic processing of CO2 may be a good step to produce liquid fuels from CO2 and electricity. Electricity is cheaper than oil at $150.

The fuel cell has demonstrated repeatedly that electrochemistry is somewhat disconnected from the second law of thermodynamics because heat is less involved. The production of mechanical energy by animals and humans also demonstrates this disconnect.

CO2 can be stored for centuries or millenia in old oil formations as was natural gas. Leakages can be discovered by known and tested means and stopped.

There are many mineral formations that will permanently take up CO2. And there is probably a way to build up massive piles of magnesium and calcium carbonates by pumping water from the ocean and mixing it with CO2, but perhaps this will require some electrochemistry for the energy. Whole islands can be built. It is known that thick layers of carbonates will form on electrodes in the ocean.



Could you expand on that a bit Henry ?



if you intend to sequester CO2 in the oceans by producing carbonates out of dissolved Ca and Mg ions, I don't think that's a good idea.
Mg++ + H2CO3 --> MgCO3 + 2 H+
Ca++ + H2CO3 --> CaCO3 + 2 H+

You sequester CO2, but you cause massive ocean acidification and you take away calcium. I don't think corals and molusks would like that.

If you use mineral Ca and Mg oxides, it would work, but that would require a different approach, as you would need to dissolve rocks.

agi anker

Hello, all
I am not one to shy away from soda, but I have been trying to cut down/cut it out completely this year. One alternative I love is carbonated water, or club soda or seltzer, or “bubbly water” as my kids put it. I feel like I’m getting that carbonated soda-y feeling without the caffeine, sugar, or sodium. What I don’t like is buying bottles and bottles of seltzer and, even though I recycled the bottles, just felt like there could be an alternative to all the liters of water.
Sodastream is doing just that - liberating people from plastic bottles and soda cans by allowing people to make their own sodas and carbonated water at home. If the average American consumes almost 600 cans or bottles of soda every year, more than bottled water - doesn’t it make sense to stop the cycle and make your own, avoiding the waste? Here are the amazing environmental benefits of a soda maker -
• No batteries or electricity
• Reduces energy used to manufacture bottles and cans
• Reduces gas and pollution from shipping packaged beverages
• Eliminates pollution from batteries
I have the Pure home soda system, and I LOVE it. It doesn’t use electricity or batteries to work - just the power of carbon dioxide injected into their special water container. It’s very easy to use - install the carbon dioxide canister, fill the bottle with cold water, attach it to the system, and inject the CO2. You can leave the carbonated water as is, or add Sodastream’s large variety of soda-flavored syrups or natural essence water enhancers to give it great flavor.
Try the link..

Henry Gibson


Yes I am concerned about the acidity of the ocean. I have no quick answer.

The shell forming life forms use CO2 from their metabolism to form shells instead of putting it into the air. CO2 is needed for all green organisms in the ocean. The growth of these organisms is also limited by the lack of other elements including iron.

It is strange that iron is contained in the blood chemicals in a nearly identical molecule as magnesium is contained in chlorophyll.

One very frightful answer is simple that humans are a plague on the earth. There would actually be no problems on the earth if humans were not present. The CO2 levels in the air may have been much higher when the plants that formed the massive coal, oil and oilshale deposits.

The oceans have a very high volume, and all the CO2 that nature saved away for later use might just not be very much if spread in the whole volume rather than just the surface. CO2 in the water with magnesium actually prevents the water from getting highly acidic because if it did the CO2 would be released to the air in order to reduce the acid content just as it is breathed out by animals.

Liquid CO2 could be stored at depths greater than 4000 feet under or mixed with mud forever.

Energy is the real issue. Homes, cars and industry will not operate without it. Oil is still the cheapest and easiest source of carbon energy to get out of the ground. Only speculation with collaberation has raised its price so that coal is cheaper.

Standard CANDU nuclear power plants can produce heat from uranium at a very low price far lower than the price from coal. Capital costs of the electrical generator and its turbine and steam generator make the price of electricity fairly high. The whole price would drop to half of less if mass produced. Nuclear elctricity could be cheap enough to extract CO2 out of the air, if necessary, to make gasoline.

Nature is losing its battle to get rid of humans so that it can have another carboniferous era for several million years, or perhaps nature is using humans to put enough CO2 in the air so that another such era would be worthwhile starting. ..HG..

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