Introduction to Carbon Capture - Introduction to Carbon Capture and Sequestration - page 147

Box 4.1.4 Pre-combustion carbon capture: chemical looping

The idea of chemical looping is to separate the combustion process into two separate
reactors. Oxygen is taken from the air by the fi rst reactor and then transported to the
other reactor, where combustion takes place and CO 2 is produced. In this scheme,
there is no mixing of N 2 with fl ue gas, therefore the separation only involves CO 2 and
H 2 O. The key question is how to separate out the combustion process. One idea is to
use a metal to transport oxygen from one reactor to another. In the air (oxidizing) reac-
tor, the metal (Me) would react with the oxygen in the air:

2Me + O 2 → 2MeO

The metal could be transported to the fuel (reducing) reactor, where it could react with
the fuel:

(2n + m)MeO + C n H 2m → (2n + m)Me + mH 2 O + nCO 2

After the reaction, the metal would be transported back to the air reactor to close the
loop.

had to decide on a technology today, we would have a very limited num-
ber of options. Of the commercially available technologies that could be
used for carbon capture today, most were not originally designed for this
purpose. Take Bottoms' amine scrubbing process, for example. In
Chapter 5, we will discuss this process in detail. Bottom developed this
process for treatment of sour gas, i.e., the separation of acid gasses