CO2 capture from high concentration CO2 natural gas by pressure swing adsorption at the CO2CRC Otway site, Australia

Natural gas is one of the fossil fuels with the lowest CO2 emissions per unit energy produced. The removal of CO2 from natural gas is therefore extremely important to promote its use. For this purpose, CO2CRC Ltd., the leading CCS R&D organization in Australia, has designed and implemented a carbon capture demonstration skid at the Australian Otway National Research Facility. The skid includes a Pressure Swing Adsorption (PSA) rig designed to remove CO2 from a high CO2 content natural gas supply in the Otway basin. Two months of operation had been carried out from May 2017 to June 2017, with the feed natural gas containing CO2 in a range from 30% to 50% using commercially available adsorbents to obtain benchmarking data. The results of operation showed that the PSA rig can successfully capture CO2 from high pressure natural gas with a recovery of 66%. However, the purity of the final CH4 product was not sufficient to meet general natural gas requirement (only achieving 80% instead of 95%). This was attributed to the fact that the operating conditions were not optimal: a final desorption pressure of 1 bar abs was desirable but only 5 bar abs was achieved. Based on our preliminary PSA operating results, process simulation were also conducted to predict the separation performance at lower desorption pressures, and showed that a methane purity of over 98% can be achieved if the desorption pressure can be lowered to 1 bar.