Pre-combustion separation of CO2

The pre-combustion separation of CO₂ is one of the techniques used for capturing and sequestering CO₂. This process consists in treating fuels (oil, coal...) upstream of their combustion.

Principle of pre-combustion separation of CO₂

These fuels are first gasified in a reactor exposed to air, water vapour or pure oxygen, in order to produce a syngas composed of carbon monoxide (CO) and dihydrogen (H₂).

This syngas then passes through a conversion reactor where it is exposed to water vapour. The carbon monoxide reacts with the water (H₂O) and produces carbon dioxide (CO₂) and more hydrogen (H₂).

The pressure and concentration of the carbon dioxide (from 15 % to 60 % dry volume) then facilitates the separation of CO₂ and hydrogen. The concentrated CO₂ can then be sequestered.

Advantages and disadvantages ofpre-combustion separation

This process is more complex and more expensive than post-combustion separation, but it produces a more concentrated gas under high pressure, which makes separation easier. It is generally applied in cycle power stations combined with incorporated gasification.