Cadmium based metal oxide sorbents for pre-combustion CO2 capture

摘要

Recent efforts in reducing carbon dioxide emissions are motivated by incentives to slow down anthropogenic climate change. Nevertheless, carbon dioxide emitting fossil fuels, like coal, are likely to continue to play a key role in the power generation sector over the near future. In order to reduce CO2 emissions while generating power from fossil fuels, the Integrated Gasification Combined Cycle (IGCC) process with CO2 capture (also known as pre-combustion CO2 capture) is proposed. In this process, coal is gasified with water in a low oxygen atmosphere to produce a synthesis gas (syngas) consisting of mostly water, hydrogen and carbon monoxide. In a subsequent water gas shift reactor, this syngas reacts to form mostly hydrogen and CO2. This shifted syngas typically has a temperature of 250 to 400 °C. It would thus be beneficial to remove the CO2 in this temperature range without the need for further cooling or heating of the syngas. The product that is left after this step would then be high purity hydrogen that could be used as a clean energy source in a combined gas/steam turbine power plant, while the CO2 is sequestered. Doiwa and Tomanek reported that cadmium oxide reacts with carbon dioxide at temperatures between 250 and 300 °C if sodium halides are present. Based on their observations, it was proposed that these materials might be suitable as sorbents in the scope of pre-combustion CO2 capture.