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Methane production and storage

  1. Sep 29, 2016 #1
    Hello members,

    I wish to produce and "store" "Methane" gas. I wish to accomplish this task by conducting out a reaction between carbon-dioxide an water. I have my own source of energy and I completely understand that the reaction is endothermic.

    The reaction is: CO2 + 2H2O + energy = CH4 + 2O2

    But, even if would successfully produce methane by this reaction, I am afraid that because of the temperature still prevalent in the closed container where the reaction took place would cause methane and oxygen to burn up again "as soon as" they are produced from the reactants(CO2 and H20) and before I can store the methane produced from the reverse combustion reaction.

    So, can anyone suggest a way through which I can trap the produce of the reverse combustion reaction (methane) without/before it being getting combusted spontaneously or "how can I stop/inhibit the reverse reaction (which here is combustion reaction) during reverse combustion reaction??" Are there some filters/membranes available which can surpass the methane produced in my container so that it can pass out through it into an environment where the temperature is not enough for the methane to autoignite.

    Any help in this is much appreciable and I trust that all of you awesome community members will assist me with this. Please do share your views and feel free to ask any further questions/doubts.

    P.S. : I don't wish to produce methane by any other reaction than the above stated, like "Sabatier reaction".

    https://en.wikipedia.org/wiki/Sabatier_reaction
     
    Last edited: Sep 29, 2016
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  3. Sep 30, 2016 #2

    Borek

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    Separation of the product would be a problem once you really produce the methane this way. Are you sure the first step is viable at all?

    In general common approach in such cases is to cool the mixture fast and/or separate the product, details vary and depend on the process.
     
  4. Sep 30, 2016 #3
    Hello,

    First of all, I would like to thank you for responding swiftly. Borek, cooling the mixture very quickly, even more quicker than the reverse reaction (combustion) in CO2 + 2H2O + energy = CH4 + 2O2 seems to be a difficiult thing. However, I really liked the second point which was to separate the gases. Even, I was also thinking in the same direction. Let me explain you about this below:

    It is a very well-known fact that if the external conditions are kept same then the reaction would finally achieve equilibrium, which means that the rates of forward and reverse reaction will ultimately become equal.

    The same would happen in this case.However, initially when the products methane and oxygen are just forming, it appears that the rate of forward reaction, which in our case is endothermic reverse combustion reaction,would be more than the reverse reaction, like in any other chemical reaction.

    The container where this reaction will take place would have a mixture of various gases like CO2, H20, (in vapor state), CH4 and O2 and some other trace gases at a very high temperature.

    Now, if I release the mixture of all these gases to a new container kept at "Room Temperature" and if I could separate methane from this mixture, I think the process is viable.

    But, the problem which I feel is, that our hero "Methane" is very shy and unlike CO2, H2O, etc. it is difficult to separate it. So, in my stance, if I could get a filter which would remove all the other impure gases like O2, H2O vapor, CO2, etc. from my container which is at room temperature, I would be left with pure Methane, which can later be compressed at high pressure in a cylinder.

    I am still doubtful if this is a correct path I am choosing or is there a better way than this to separate methane from a mixture of gases. If anyone has knowledge about this please share. It would be very helpful.
     
  5. Sep 30, 2016 #4
    The problem here is that combustion of methane is highly spontaneous reaction. So, any suggestions to decrease the spontaneity of this combustion reaction, so that the hard earned products (CH4 and O2) after using a lot of energy don't get converted back to CO2 and H20 directly producing heat there and then only in the container. If this happens than all the heat generated by the spontaneous combustion would be wasted and released in the atmosphere without I being able to get some useful work from it.
     
  6. Sep 30, 2016 #5

    Borek

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    If cooling the mixture is difficult then how are you going to release the mixture to a room temperature container? That requires cooling of the gas, doesn't it?
     
  7. Sep 30, 2016 #6
    Well, for that purpose I will use another closed container kept at a distance from the original container. Both the containers will be connected by an insulted pipe and a kind of automatic operating valve. So, lets say the original space where this reverse combustion reaction takes place has temperature of around 400-500 degree celcius, the connected container would have a tempature of around 45-50 degree celcius as both the containers would be connected by an impeccable insulating medium (pipe) so conduction of heat would be very less and if required air/water cooling can also be employed.
     
  8. Sep 30, 2016 #7
    Or can I use something which can remove only oxygen/methane from the mixture as soon as they are generated like some sort of a "permeable membrane" which would allow only a characteristic gas to pass from the mixture, out into the atmosphere, to inhibit the spontaneous combustion process?? But, I am not sure if such filters are available commercially.
     
  9. Sep 30, 2016 #8

    Bystander

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  10. Sep 30, 2016 #9
    Hi, thank you very much for your contribution. I read the link which you mentioned. I really got to learn about the new things in the link. But, the information in the link is primarily focussed on production and uses of copper(II) oxide . Is it that, this chemical bears the potential of making a very good membrane to filter the gases??
     
  11. Sep 30, 2016 #10

    Bystander

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    :wink:
     
  12. Sep 30, 2016 #11
    Thanks bro...i 'll definitely take the chemical into consideration. Your active participation was really useful for me. I hope you'll continue.
     
  13. Sep 30, 2016 #12
    Hello members,

    A good news.... I found a similar thread in which the original creator was working on a similar project like mine. Below is the link of that thread.


    Here my problem is also very much identical. My concern was about the spontaneous combustion reaction which would transform all the hard-produced CH4 into CO2 and water again.

    Now, if I am able to remove the Oxygen somehow from the mixture as soon as CH4 and 2 moles of O2 are produced then I believe risk of spontaneous reaction will reduce significantly.

    Refer to the post #15 in the physicsforums link provided below:

    https://www.physicsforums.com/threads/oxygen-absorber.120653/

    The creator of this thread wanted to produce hydrogen and store it in a tank. So, his/her intentions seem similar to mine, the only difference being, I want to produce methane instead of hydrogen using a reverse combustion reaction.

    Dear members, I humbly request you to share if you have anything which can inhibit the spontaneous combustion reaction as chemistry is not my field of expertise and I trust that you guys have a lot of knowledge with regard to this. Please participate.
     
  14. Sep 30, 2016 #13
    This site is really helpful and I really wish that I can get in touch with the creator of above mentioned thread directly. They were last seen somewhere in june 2016 and tge above thread was created some 10 years back.
     
  15. Sep 30, 2016 #14
    Moreover, upon googling I found that some starups like "Liquid Light" are already working on this technology. However, their main energy source is sunlight. My source of energy to drive this reverse combustion endothermic reaction is different though.

    To find more about "sunshine to petrol (fuel)" refer to the link attached below. The information is provided in a very lucid and believe me, the topic is interesting.

    http://large.stanford.edu/courses/2012/ph240/maas1/

    The only thing which makes me wonder that how these guys manage to store the hydrocarbons produced by reverse combustion for future utilization, without the products (hydrocarbons) getting burned up spontaneously as soon as they are created.

    This is mentioned nowhere. Conducting a reverse combustion reaction is not a big deal but the trouble lies in storing the products of this reaction securely without getting burnt up no sooner than they are generated.
     
  16. Sep 30, 2016 #15

    Borek

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    This is a standard problem with every reversible reaction, which basically means most processes in the chemical industry have to deal with it.

    If I can suggest something, try to find a book on chemical engineering and start to learn from the beginning. Sounds like you are trying to run without knowing how to walk.
     
  17. Sep 30, 2016 #16

    mfb

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    I would be surprised if your chemical equilibrium has a relevant amount of methane at any reasonable temperature. Sure, there will be some methane, but it doesn't help to have a few molecules around. You can calculate the equilibrium concentration - that is something I would do first before investigating how to separate the gases. A multi-step synthesis via catalysts can be way more efficient.

    Your reaction in post #1 has H2O2 instead of water.
     
  18. Sep 30, 2016 #17
    Yes, you mentioned a really important parameter here which I left. I understand that here it is very much important to find the value of equilibrium constant (K) for both the forward as well as reverse reactions before actually conducting the "Reverse Combustion" reaction in the reaction chamber.

    However my concern is that as the spontaneity of CH4+ 2O2 reaction is far morre than CO2 + 2H20, I am afraid that before I collect methane produced it would burn up spontaneously due to high temperature in the reaction chamber and obviously the temperature im the combustion chamber would be high because I am going to perform reverse comnustion which is a highly endothermic reaction. So, I feel that I would have to seperate methane as fast as possible from the reaction chamber to save it from gettimg converted back to CO2 and water.

    Your reaction in post #1 has H2O2 instead of water

    Reference https://www.physicsforums.com/threads/methane-production-and-storage.887300/

    I did not get what you meant by this. Are you suggesting that I should yse hydrogen peroxide (h2o2) instead of 2 moles of water as a reactant ??
     
  19. Sep 30, 2016 #18

    mfb

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    I misread the 2H2O as H2O2, sorry.

    Getting the methane out won't be trivial, but to worry about that you first need a relevant amount of methane. The large concentration of CO2 and H2O helps to lower the reaction rate.
     
  20. Oct 1, 2016 #19
    Borek thanks for the suggestion. I will do that to check for the techniques which are available and if you have any knowledge about any such good book which will shed some light in this matter, please share it . It would prove to be very useful for me. Thank you everyone for your contribution. Please feel free to share your knowledge/advice or vote.
     
  21. Oct 1, 2016 #20
    Mfb, yes you seem to be right a very large concentration of CO2 and H20 could actually hinder the rate of production of methane even though they are the ingrediants to produce methane in the first place.

    So, here what I think, is to devise a reaction chamber wherein appropriate amount of CO2 and H20 will be taken and heat will be supplied to convert them into CH4 and O2. And then after a "pre-calculated time" by which these CO2 and H20 has been converted to products CH4 and O2, an "automatic operating gas-release valve" fitted to the reaction chamber would open and allow the gases to diffuse to another container at room temperature.

    This process will be repeated for several cycles so as to collect a considerable amount of methane in the second container. Then the methane will be seperated from the mixture of gases from the second container and finally compressed in a cylinder.

    So this is my plan of execution of significant amount of methane production and storage.

    Please don't hesitate to put your views.
     
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