The fuel here doesn't react with air, but with a solid oxidiser (Fe2O3). It's a solid-solid reaction, whose products are gases (CO2 and H2O). Just like a solid-fuel rocket.
It's not different, but it's a pure gas and not mixed with a ton of nitrogen that air combustion exhaust would be. That makes it trivial to capture (literally just pump it through a compressor into a tank).
One important point, though, is that the sequestration problem is not actually addressed here. This just gets you conveniently-produced tanks of CO2 (or crates of dry ice, whatever). What you do with that to keep it out of the atmosphere is still an open problem.
https://www.google.com/search?q=define+fire&oq=define+fi...
The fuel here doesn't react with air, but with a solid oxidiser (Fe2O3). It's a solid-solid reaction, whose products are gases (CO2 and H2O). Just like a solid-fuel rocket.