Simpler, cheaper way to make liquid methanol fuel using CO2 and sunlight
Most previous methods of producing methanol from carbon dioxide have involved lots of electricity, high pressures and high temperatures, and used toxic chemicals or rare earth elements like cadmium or tellurium. A team of researchers at the University of Texas at Arlington (UTA) has developed a new method they claim is safer, less expensive, and simpler than current approaches and can be scaled up to an industrial scale to allow some of the CO2 emitted from electrical power plants to be captured and converted into a useful fuel.
The simplest of the alcohol molecules (and poisonous to humans), methanol (CH30H) can be turned into a form of bio-diesel fuel and burned in engines. It is also an important chemical in the production of plastics, adhesives, and solvents.
In an interview with Gizmag, Dr Krishnan Rajeshwar, a distinguished professor of chemistry and biochemistry and co-founder of the Center for Renewable Energy, Science & Technology, CREST, at UT Arlington, described the new methanol production process developed by his team as a photo-electrochemical version of photosynthesis that occurs in plants.
The heart of this technique uses a thermal process to coat copper oxide (CuO) nanowires with another form of copper oxide (Cu2O) and submerging them in a solution rich in carbon dioxide. The CuO-Cu2O hybrid nanorod arrays were then subjected to sunlight – or simulated sunlight in the lab – to trigger a chemical reaction and produce liquid methanol. The team says the experiments generated methanol with 95 percent electrochemical efficiency and avoided the excess energy input, also known as overpotential, of other methods.
When asked if this process might be used to create fuel for remote locations in Alaska and Canada, far from pipelines and roads, Dr. Rajeshwar thought it might be combined with the output of generators that make electricity, recovering the CO2 waste gas pollution to produce useful fuel.
The team's experiments were done on a very small scale, but the UTA team is now raising money to continue work on scaling up the process as part of their quest to create commercial products out of their research. “We hope the solutions in the lab are only the beginning”, said Carolyn Cason, VP for research at the University.
“As long as we are using fossil fuels, we’ll have the question of what to do with the carbon dioxide,” added Rajeshwar. “An attractive option would be to convert greenhouse gases to liquid fuel. That’s the value-added option.”
The UTA team, which also included Ghazaleh Ghadimkhani, Norma Tacconi, Wilaiwan Chanmanee, and Csaba Janaky, recently published their findings in the January 21, 2013 issue of Chemical and Engineering News.
Source: UT Arlington
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But running CuO dust in a fluidized bed reactor might do the same and not have to pay for catalysts we might never be able to buy .
I'd rather have something farther up the HC and without O2 in it like Octane and other gasolines. But Methanol if easy will do. Very low energy with only 40% of gasoline, even worse than ethanol's 60%.
According to the US DOE (Energy) Website http://www.afdc.energy.gov/fuels/fuel_properties.php methanol has 49% of the energy of gas and using their numbers I calculated pure ethanol as about 65% of the energy of gas. (Either way still more practical than battery stored electricity.)
Be for it or be against it, but please try to use the right numbers.
I lost my CRC of Chemistry and Physics long ago so will accept you figure for the thermodynamic energy difference between methanol and H20 +CO2.
Our reaction would be 2CO2 + 2H2O -->2CHOH +O2. Yes the reaction is endothermic as CHOH has higher potential than H2O and CO2. However this reaction takes place within photosynthesis. The energy of reaction is provided by light.
Basically this is a photochemical reaction. The cuprous oxide/cupric oxide substrate acts as a medium changing the energy required to drive the reaction from one steady state to another steady state. As you remember from you chemistry stable compounds usually must provide sufficient energy to overcome an energy hump that holds the molecule in its current state. Exothermic reactions continue as the released energy from the reaction is sufficient to move more of the substrate molecules to the transition state at the top of the hump. Without this energy hump all molecules would immediately react to transition to the lowest energy state. In the case of CHOH it would effectively not exist as CO2 and H2O both have much lower thermodynamic energy.
A catalyst only allows for a reduction in the height of the hump via intermediate reactions or simply changing of conformation in such a way as to allow the reaction.
The earth when the sun is directly overhead receives about 1KW/m^2. Of this about 450W/m^2 is in the physical bandwidth. I do not know exactly which bands are used of photosynthesis but presume most is visible light.
As you have 2 different states of copper bonded together this would naturally yield a small electrical charge much like using 2 different metals. From the article I can not tell but it is also possible the two states basically when struck by light end up forming a positive side and a negative side similar to what happens with the Hall effect where at right angles to the direction of flow of the electrons and right angle to the magnetic field, you will generate a small electric field where one side of the wire becomes positively charged and the opposite side negatively charged.
If the system is indeed partially mimicking photosynthesis electron transport mechanism is far more important for the reaction than in normal reactions. The light provides both the energy and a source of the electrons due to collisions with the plate.
As to cost of materials, they should actually be trivial. The mesh of wires are on the nano scale. That means a mesh even 1000m x 1000m would still contain little copper (1,000,000 m^2 at say 1 micro thick = 1 m^3 of copper. ) and I really doubt even an industrial application would stretch a Km^2. If the system does indeed yield high amounts of CHOH, it would probably reach 100% ROI within a few years and that is assuming all new construction for the plant.
It is already usable in IC engines, and has been in various forms of motorsport for over 60 years
Methanol is a 'building block' molecule for just about any hydrocarbon using well known 'hydrogenation' processes (Fisher-Tropsch is used in oil refineries) to produce gasoline, diesel fuel, plastics, etc.