chemrox
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CO2 to CO
As part of my ongoing effort to discover possible solutions to the end of cheap and easy petroleum, I've been re-reading the Fischer-Tropsche process.
This Fischer was an amazing scientist. He devised methods for making petroleum by the carload in small plants. But he was starting with coal
gassification and using CO as a precursor. Id like to read anything done on CO2 reduction and am having trouble finding sources or formulating the
right search terms. If we could start with CO2 we'd at least have a CO2 balance. I need to find out what I'm up against. The change in entropy is
about 30 kJ/mole. That doesn't seem an insurmountable barrier in itself.
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Ozone
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It is much easier to perform a "lean" oxidation than a reduction of any sort. Gasification tends to be a compromise between substrate reactivity and
O2 applied at the given temperature.
So, where it is relatively simple to produce CO (and H2) from biomass, lignite, etc., it is not easy (or energy efficient, in *most* cases) to reduce
CO2 to CO (unless you can invent a really efficient, stable catalyst operating under recycled H2).
Reformer gas might be an option, but I tend to go with the devil I know.
Cheers,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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not_important
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But generating CO from carbon (coal) means using more fossil fuel, as does making it from natural gas.
A search turned up a recent conversation on this, with some numbers, and some alternative fuels as targets rather than petroleum-like fuels.
http://www.dailykos.com/story/2007/2/21/94023/9685
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Ozone
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True,
But making it from reactive agriwaste (bagasse, corn stover, etc.), with the exception to the loss of total high heat value (which is lost in the
conversion) is feasible (see fluidized bed).
Too bad that the steam engine is not "in vogue"; conversion to more standardized fuels results in a net loss of fuel value.
Good night,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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12AX7
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CO2 + H2 = H2O + CO. I don't know if this is exothermic, check it.
Also, CO2 + C = 2CO. If you're talking about making petroleum, you'll be using up carbon anyway. This reaction is easily observed in a thick bed of
ignited charcoal (or other carbon) with slow air blast.
Tim
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not_important
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| Quote: | Originally posted by 12AX7
CO2 + H2 = H2O + CO. I don't know if this is exothermic, check it. |
copied from the link I gave earlier:
Making carbon monoxide
CO2 + H2 <=> CO + H2O takes 41.2 kJ/mol
| Quote: | Also, CO2 + C = 2CO. If you're talking about making petroleum, you'll be using up carbon anyway. This reaction is easily observed in a thick bed of
ignited charcoal (or other carbon) with slow air blast.
Tim |
The point is to not use fossil carbon, but either sequestered carbon dioxide or recent biologically fixed carbon.
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12AX7
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Well, it's quite easy to convert "recently biologically fixed carbon" into carbon carbon. You even get workable distillates in the process of
producing this carbon. (I even posted "charcoal", not specifically "coal" for instance.)
Tim
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bereal511
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Why not work directly from biologically fixed carbon? It seems as though the energy usage to convert carboneceous compounds into petroleum is a bit
wasteful, when you could probably thermolyse or pyrolyse the material.
As an adolescent I aspired to lasting fame, I craved factual certainty, and I thirsted for a meaningful vision of human life -- so I became a
scientist. This is like becoming an archbishop so you can meet girls.
-- Matt Cartmill
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12AX7
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Nobody wants to convert their car to a Stirling powered car that needs to be shovelled full of wood pellets and warmed up perhaps a whole minute
before use.
Tim
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bereal511
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| Quote: |
Originally posted by 12AX7
Nobody wants to convert their car to a Stirling powered car that needs to be shovelled full of wood pellets and warmed up perhaps a whole minute
before use. |
Well, not quite what I meant by working directly with fixed carbon. The actual conversion would be worked on an industrial of course. If one were to
convert the wood components to distillates in a more direct fashion (i.e. pyrolysis) and collected/refined to petroleum-like compounds, would it not
be less energy intensive? Pyrolysis occurs at around 500 degrees C and hydrothermolysis occurs around 200 degrees C, while biogasification would need
up to 700 degres C to occur.
As an adolescent I aspired to lasting fame, I craved factual certainty, and I thirsted for a meaningful vision of human life -- so I became a
scientist. This is like becoming an archbishop so you can meet girls.
-- Matt Cartmill
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chemrox
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| Quote: | Originally posted by not_important
But generating CO from carbon (coal) means using more fossil fuel, as does making it from natural gas.
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Yes, that's why I'm trying to develop a catalyst for the conversion of CO2 -> CO
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chemrox
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| Quote: | Originally posted by 12AX7
Nobody wants to convert their car to a Stirling powered car that needs to be shovelled full of wood pellets and warmed up perhaps a whole minute
before use.
Tim |
Nobody will want to convert his car until there's no more petroleum.
The US is waging war on the middle east to get the last 100b barrels.. at least that's how I see it .. no wonder they're pissed off.
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Levi
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| Quote: | Originally posted by 12AX7
Nobody wants to convert their car to a Stirling powered car that needs to be shovelled full of wood pellets and warmed up perhaps a whole minute
before use.
Tim |
Lol. I do! Where can i get one?
Chemcrime does not entail death. Chemcrime is death.
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not_important
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| Quote: | Originally posted by chemrox
| Quote: | Originally posted by not_important
But generating CO from carbon (coal) means using more fossil fuel, as does making it from natural gas.
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Yes, that's why I'm trying to develop a catalyst for the conversion of CO2 -> CO |
There are many known catalysts for the reaction, and some that take you to products further downstream. I think it mentions to Korean process for
taking CO2 and H2 to dimethyl ether, an alternative fuel. Note that there are cleaner buring - less NOx and particulates - fuels than the conventional
long chain hydrocarbons; most of these fuels are also better targets for production from CO2 or CO, better conversions, less byproducts.
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