Breaking apart CO2 into C and O2 - This needs some research...
Breaking apart CO2 into C and O2 - This needs some research...
Submitted by Richard Belshaw on 15 December 2007 - 8:43am.
Breaking down CO2 to carbon and O2
Submitted by Richard J Belshaw on 4 February, 2007 - 00:30. The following is not from a textbook and i am the sole author and hence hold the copyright Feb. 4/2007
addendum (added after original article written: Anaerobic bacteria can use CO2 as food source, and produce O2 and carbon biomass that can be used as a fuel, usually bacteria also needs sugar, which is expensive as an energy source in terms of producing it, fertilizing sugar cane or beets, refining and transportation)
The chemical equation: CO2 --> C + O2 has the following enthalpies of formation and entropies(relative, not absolute) Enthalpy of formation
Hf -393.51 ---> 0 + 0 listed as J/Mol in introduction of CRC student edition of handbook of chemistry and physics (# 75) Entropy
S 213.8 ---> 5.74 + 205.2
listed as J/Mol/K so i definately do not believe, using common sense, that 400000 Joules are released by one mol of carbon when burnt in oxygen.... it seems out of all proportion...(if one quickly reads the tables and takes the kJ/Mol of the top of the table, which is either code, or a misprint), so it must be in J/Mol, because one mol of carbon weighs about 12 grams usually (except for carbon 14 isotopes, which are trace amounts normally), and so 12 grams burning in one second, cannot produce 400000 Watts of energy.... so it must be 400 Watts , hence it must be J/Mol using scientific reasoning and common sense....
According to Gibbs free energy at
298.15K DeltaG = DeltaH - T*DeltaS DeltaG = (0+0+393.5) - 298.15*(205.2+ 5.74 - 213.8) = 393.5 - 298.15*(-2.86) Joules > 0
So this reaction would not normally proceed. However, if the entropy change (DeltaS) were positive, ie. changed by just 4 or 5 J/Mol, then this reaction should proceed. In fact the critical amount is... 4.18 J/Mol at room temperature (15 degrees Celcius)!!! Lets make it 5 J/Mol just for good measure... then .... This analysis shows that normally the reaction proceeds in the other direction..... But common sense tells us that it needs either heat or fine tuned EM spectroscopic frequencies to proceed( activation energy). So if we provide heat (to a certain point) and we provide more entropy on the reactants side, then the reaction above should proceed. This would take some research. Clearly, we just need to increase the entropy of the products, without affecting that of the reactant. To do this, we need to add energy or entropy to the equation, without affecting the entropy of the CO2 molecule. ie. we MUST NOT vibrate the C=O bonds in CO2 beyond a certain point (or rather we must make sure that the products have more entropy than the reactant, and that ignition or combustion temperature for C + O2 conditions are not met, ie. we keep the temperature and sparks away from those thresholds), but we must increase the energy of the O=O bond, and perhaps provide energy to the resonant frequencies of the graphite molecule as well... so that the Carbon atoms have something to form after dissociation..... If we provide an EM field of microwaves or UV light such that the CO2 molecule is induced to cleave (by increasing its bending moment while keeping the temperature relatively low and below combustion temperature of the C +O2 product mix), and the entropy of the products is larger and such that DeltaS is positive, then this reaction would proceed at fairly low temperatures...... If we put such an installation on Greenland and on Antarctica and several other locations around the globe. We could produce Graphite for very little energy input and produce excess oxygen, and remove steadily (until world CO2 levels had stabilized at an acceptable level) the CO2 from the atmosphere.... this would be a way to remove the threat of global warming due to CO2 in the atmosphere....with two useful byproducts. Naturally, the energy to drive the process must NOT come from Gas or oil or combustion, but must come from solar, wind or nuclear in order for this process to do any good.... but the technology is here and we could design a solar collector like they have in arizona and Merkel is planning to put in the Sahara, this would provide a standalone installation that could adequately chug away, on an on again off again basis based on CO2 diffusion in and out of the region.... Studying the wind patterns would be necessary to keep the process on more of the time or not, and coordination with places like Mauna Kea and Charles Keeling and global CO2 measurements to control the drop in CO2 in the atmosphere would be necessary. Would this process really make a dent in world CO2 levels, given the amount that is being put into the atmosphere, these are sirius engineering calculations..... perhaps we need a whole string of these installations right across the arctic to make any serious contribution to CO2 stability levels. Research into the exact mix of resonant frequencies required to generate and the design of the magnetrons, UV lamps(LEDs) and and the quantum mechanics involved so as to avoid dangerous frequencies for personnel working on the installation are also requirements of the design.....
Absorption spectra in the atmosphere(ie. by O2) http://www.udel.edu/Geography/DeLiberty/Geog474/geog474_energy_interact....
The absorption peak, near 100% absorption for microwaves, is about .2 cm wavelength and 150 GHz.
It truly would be an interesting experiment to expose some air in a chamber that contained atmospheric concentrations of gases,
and pump in 150GHz.
We need 5 J/Mol to possibly convert CO2 to O2 and Carbon..... some CO would likely develop too, but this is not as nasty a GHG.
Lets assume for the moment that all the CO2 goes to O2 and carbon. 1Litre of air at STP contains 5.22x10^22 molecules of gas. of which, 21% is oxygen to start. This means if we add 5J/Mol to oxygen, (1 g-Mol = 6.023E23 molecules)therefore
5 J/Mol*(5.22E22*.21/6.023E23) = .091 J/Litre
must be added on average to excite the oxygen molecules..... ie. to increase their entropy sufficiently to make the reaction go (according to DeltaG = DeltaH - T*DeltaS
#photons required comes from the equaton: 0.091 J/Litre = 6.626E-34 J.s/particle * 150GHz * x particles/Litre x = 9.16E23 photons of 150GHz microwaves are required to enter the litre
.... approx 10E24 in total. If it can take place over two seconds, we only need .046 Watts. Say this happens in about .01 second , then we get .091J/.01sec = 9.100 Watts
So we need a magnetron capable of between .1 and 10 Watts in order to carry this out, preferably over shorter time frames like half a second(approx. 0.2 Watts)
775 GT = 1.76E16 Mols at 15 degrees Celcius = 4.165E17 Litres at 101.325kPa
4.18J/Mol*1.76E16 Mols = 73568 TJ (Terra Joules) to process 775 GT of CO2 gas to carbon and oxygen gas.
Maybe even magnetic fields or acoustic vibations are required to separate the carbon particles from the oxygen molecules,
8.8E16 Watts or 88000 TWatts is required or 114 TWatts per plant at 1GT per plant per annum.
This is not exorbitant for 1 Litre, but we would need to upscale it for larger production,
and we would have to experiment with the time frame required for optimal results....and least diffusion of temperature in that time...
This is also a maximum estimate. The energy required to excite ALL the O2 molecules in the litre to the 5 J/Mol increase....necessary for the reaction to go. However, if one could concentrate on just the CO2, which is at 380 ppm or so, then the ball game would be very different indeed. If there were a way to separate out the CO2 , or remove the O2 from the mix in the first place, then all we would need would be on the order of: 0.00038 * 0.200 W = 76 microWatts/litre....!!!!!! very small indeed....
So assuming we process, 10 litres per second... 1 billion tonnes of CO2 processed 1E12 grams, would take approximately... 2.2727E10 mols of CO2 at 298.15 K this would be...at 101300 Pa and R=8.314 J/Mol/K V = n*R*T/P = 5.5613 E 8 Litres it would take at 10 litres per second, 380 microWatts per litre, at 80% efficiency for an effective magnetron, this would be... 475 microWatts per litre A total of 264 kW Watts, and 1.77 years.... If we could speed up the process, we could spend the energy more quickly, and reduce the time it took to get rid of 1 billion tons, or we could build several plants in parallel.... 50 plants would get rid of 50 GT in 2 years.... at a total energy cost of 13.2 MegaWatts.
http://www.zeusinc.com/ptfe_tubing.asp?source=G_ptfe&gclid=CO2q2-CLrooCF... here is a link that offers PolyTetraFluoroEthylene Tubing (PTFE) that can be extruded with different pore sizes. It can be offered with sizes that pass Argon, N2, and Oxygen, but not noticeably CO2. With this type of tubing, and many of them in parallel and a big fan, all the gases over long enough tube lengths, and high enough pressures , and enough time, will yield a result of just the CO2 in the atmosphere. If you couple that with the original post, and build a magnetron around 150GHz.... You might be able to turn All the CO2 into carbon and oxygen.... no sparks please....
very delicate....and the oxygen would have to be removed... but it is larger and heavier than the carbon.... if you heat it up with microwaves, the oxygen will rise, but the carbon will not.... issues such as, how long to expose the CO2 to microwaves, what kind of pulse, etc.... are necessary, and how to separate the O2 from the carbon at the finish with no sparks please....
More chemistry... spectroscopy Submitted by Richard J Belshaw on 25 February, 2007 - 23:49. In MRI techniques, very similar to NMR in principle, with which you might be familiar... There are myriad sequences of radio wave pulses that can prepare and probe the substances and tissues.... Similarly, i think, a special microwave sequence, might be attempted, perhaps from one , two or more magnetrons in concert and sequence, such that the oxygen atoms in the CO2 are 'tickled' and provoked to react in CO2 .... followed by sequences that move the CO2 down a chain of events, such that , the oxygen molecule O2 has more entropy than it would otherwise have, and more than the CO2 molecule such that the reaction proceeds.... is this at all possible in your opinion... why or why not? Richard
A chemist friend of mine replied: First you'd have to collect the CO2 in one place costing a huge amount of energy. Second in a resonant chamber a mile or two long you would have pump in microwaves at a huge power over a range of specific microwave frequencies to set the molecules rotating fast enough to cause them to fly apart by centrifugal force which are exactly equal to the freequencies required for the allowed transitions. However because CO2 does not have a dipole in its ground vinrational state there is no spectoscopically allowed transition from the ground state and you would have to heat it up to about 1000 C (Boltzman distribution governs this)to excite the the molecules into the bent one way to bent the other state vibrationally excited state. You might then be able at very low efficiency get the microwave energy into the moilecules to rotate faster. As the molecules rotate faster they stretch causing the right microwave freqency to get them spinning faster to increase in frequency. And now if a few molecules break apart you have to stop the carbon at 1000C from catching fire in the oxygen you've made.
The true key lies in Quantum chemistry. If we can create the bending moment of the CO2, below the combustion temperature of C and O2, with irradiation by microwaves or whatever, AND increase the entropy of the products, the reaction might just go, with practically no danger of combustion. Extreme care must be taken however, and this requires a lot of care and control systems. Temperature alone, the brute force method, is not recommended and is energy inefficient.
One might say, but a gas of particulated carbon and O2 is a perfect fuel. True. If one were to burn it, one could obtain extra energy, but then we would be back where we started from, and would have CO2 again. One then asks, isn't this a perpetual motion machine.... NO!!!! It takes more energy to run the closed loop than the energy one gets from it. No free lunch, 2nd law of thermodynamics NOT BROKEN. However , it may be the cheapest and most energy efficient way to break down CO2 into C and O2. the tricky part is, how do we separate the C from the O2 once the dissasociation has occurred. One technique is to use diffusion again. The carbon particles would readily combine with each other to form lumps of carbon dust, if given enough time to bump by brownian motion into each other.... the O2 would be excited and warm, and would therefore rise, while the carbon dust would settle... we can remove the O2 at the top of the chamber by diffusion, Questions: How long before the carbon combines and settles. How long before it is safe to remove the O2. Do we use the resulting products as a fuel? Where does the energy come from to run the closed loop cycle? is our aim to generate a fuel, or remove CO2 from the atmosphere? We need to follow through with our intended aim.
Other questions: In MRI they use radiofrequency pulse trains that are exquisitely crafted to get the highest quality signal out of tissue with the least exposure, and achieve various results from fMRI to just plain tissue imaging with T2 relaxation times and spatial resolution. If we were to get that fancy with this process, we could tickle the CO2, O2 products with microwave pulse trains, designed to cause dissociation inexpensively energy wise, and yet keep the temperature safely below the ignition and combustion temperature of 'fine coal dust' and excited O2. A very delicate operation indeed, but not impossible.
The CO2 has a quadrupole, and hence has some absorption frequencies.... see the attached document....
Without constraints it is unlikely that anything of any value will ensue Richard Belshaw Wellington-Halton Hills EDA Copyright Feb 4/2007 Richard J. Belshaw, All rights reserved.
Without constraints it is unlikely that anything of any value will ensue Richard Belshaw Wellington-Halton Hills EDA
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Or let plants do it for free
Submitted by Andrew Lewis on 15 December 2007 - 1:48pm.
Your post Richard is very long and focuses on a technical fix for excess CO2, which perhaps points to the cultural problem we face as we tend to rely on human technology, while all around we have billions of years of far superior evolutionary design to work with. In this case, plants. Plants remove CO2 from the atmosphere, for free! So perhaps all that technical know how, and associated cost, should be put aside and lets focus on restoring the forests of the world. Protect, conserve and restore ecosystems will ultimately be the answer to achieve climate balance.
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Problem with plants...
Submitted by Richard Belshaw on 15 December 2007 - 2:20pm.
Plants require nutrients, minerals, certain fertilizers, CO2, sunlight and plenty of H2O. In fact they sequester H2O, and may be a major reason for increasing number of droughts around the world elsewhere. Sunlight might be becoming in shorter supply due to global dimming (particulate matter from India and China and developing nations, and coal from developed nations and volcanos). Plants would other wise be a perfect choice. However the main problem aside from the comments i just made are that CO2 has risen since 1850 or thereabouts and in fact O2 has become depleted by a significant percentage. Especially right now, CO2 is rising 2.5% per year, and the rate of increase is still increasing (if you understand calculus). O2 is still declining and the rate of decline is increasing. 30 mpg autos gobble 273 litres of O2 per minute, and produce 175 Litres of CO2 per minute (half these numbers when idling approximately) the centroid car is probably around 20 to 23 mpg. Transportation represents only 25 to 30% of the problem, the rest being gobbled and produced by industry respectively. The GDP and GNP of nations is still growing exponentially, as is population. The plant life out there cannot keep up without radical transformative technologies. Plants alone are not enough. The math just doesn't add up. So we need to increase energy efficiency (with technology), reduce emissions (with caps, carbon tax, etc...) and reforest... but we need to carefully analyze this water sequestration thing, otherwise some areas will become more desertified, not less.
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