Does combustion have to produce gaseous CO2?

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    Co2 Combustion
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Discussion Overview

The discussion revolves around the nature of combustion processes, specifically whether combustion of fossil fuels must produce gaseous CO2 or if it is possible to generate energy while producing only liquid or solid by-products containing carbon. Participants explore the implications of different chemical reactions and the feasibility of alternative oxidizers in combustion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants express curiosity about the possibility of fossil fuel combustion producing only liquid waste containing carbon, questioning if this is feasible or if there are fundamental scientific principles preventing it.
  • Others clarify that typical combustion processes of fossil fuels, which primarily consist of hydrogen and carbon, naturally produce CO2 and water vapor when oxidized with atmospheric oxygen.
  • A participant raises the idea of using alternative oxidizers that might allow for different combustion products, but acknowledges the challenges associated with safety and practicality.
  • There is mention of existing petrochemical reactions and carbon sequestration methods, but uncertainty remains about why certain approaches are not more widely discussed or implemented.
  • Concerns are raised about the handling and safety of potential alternative oxidizers, suggesting that they may be more hazardous than CO2 itself.

Areas of Agreement / Disagreement

Participants generally agree that typical combustion processes produce CO2, but there is no consensus on whether alternative methods could exist that would allow for different by-products. The discussion remains unresolved regarding the feasibility of such alternatives.

Contextual Notes

Participants express uncertainty about the energy output of potential alternative reactions and the specific nature of by-products that could be produced. The discussion highlights limitations in current knowledge about chemical reactions that could replace traditional combustion processes.

Who May Find This Useful

This discussion may be of interest to those exploring alternative energy sources, combustion chemistry, environmental science, and carbon sequestration technologies.

  • #31
You could think of oxidizing alkanes only partially, e.g. to formic acid. However, formic acid is toxic and also volatile. So in praxis not much easier to store than liquid CO2.
An exotic possibility would be the reaction 5C+3/2 O2 +CaCO3 -> Ca C6O6, the latter being known as calcium rhodizonate. A solid, very appreciated in analytic and forensic chemistry. Would be interesting to know the enthalpy of the reaction.
 
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  • #32
Simply put CO2 and H2O are the thermodynamically stable products obtained when burning hydrocarbons. Of course multiple intermediates exist but these are all radicals and highly reactive. In order to burn hydrocarbons in a controlled fashion, think of biochemical processes. These require highly complex supramolecular machineries to convert sugars into CO2 and H2O aerobically and lactic acid or ethanol anaerobically making use of relatively stable intermediates. I'm not even sure if it would be possible to halt these reactions in the presence of O2 to get something like an ethanol product. Probably more radical chain reactions would be induced. So producing anything else from hydrocarbons in the presence of oxygen than CO2 and H2O is unlikely.
 
  • #33
I think certain metals can be "burned" (perhaps oxidized in a solution, or whatever). Aluminium comes to mind.

Of course we need to make the aluminium first, which takes energy. Energy from other sources (nuclear power, solar) could be concentrated for use as fuel in aircraft or the like, or CO2 could be made into octane (gasoline) which would be carbon neutral when it was subsequently burned.

These technologies are all relatively expensive currently.
 

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