Pre combustion CO₂ capture

Especially for coal, but also for natural gas and biomass, pre-combustion CO₂ capture offers an attractive way to separate CO₂ at relatively low costs. Moreover, next to electricity, other products like hydrogen can be produced.

In the conventional process, the fuel is first converted into syngas using gasification or reforming. After gas cleaning, the CO is converted into hydrogen and CO₂ in the water-gas shift (WGS) reaction, and CO₂ is captured using a solvent.

The ECN program is focused on combining the shift and CO₂ capture steps in a single reactor, which offers the opportunity to lower the capital costs, to increase the CO₂ capture ratio and to lower the efficiency penalty. 

1.      Sorption-enhanced water-gas-shift (SEWGS)

In the SEWGS process, the water-gas-shift reactor and the CO₂ separation are combined and carried out at 400°C, close to the inlet temperature of the gas turbine, thus eliminating expensive heating and cooling steps. 

2.    Sorption-enhanced reforming

Reforming of natural gas is combined with CO₂ sorption at high-temperature. The capture of CO₂ inside the reforming reactor enhances the hydrogen production. The CO₂ sorbent is regenerated in a separate step, yielding a high-purity CO₂ stream. 

3.      Hydrogen membrane water-gas shift

In a hydrogen membrane reactor, a Pd-based membrane separates the hydrogen product generated by a WGS catalyst from the CO₂ rich gas. Like in SEWGS, this enhances the hydrogen production and combines WGS and CO₂ separation in a single step at the inlet temperature of the gas turbine. 

4.    Catalysts

In both the conventional as in the integrated pre-combsution CO₂ technologies, catalysts are needed for the water-gas-shift reaction and natural reforming reaction. ECN tests commercial catalysts and develops novel catalysts for these processes.