Low-Temperature\nPhase Separation of CO<sub>2</sub> from Syngas MixturesExperimental\nResults

To mitigate the increasing anthropogenic CO<sub>2</sub> emissions,\nhydrogen is pointed to as a potential low-emission alternative fuel\nfor a range of applications. Gray hydrogen from natural gas reforming\nis the dominant industrial hydrogen source globally. If CO<sub>2</sub> capture and storage can be added with minimal efficiency reductions,\nblue hydrogen can reduce the carbon footprint drastically. A novel\ntechnology option for blue hydrogen production, is the use of proton\nconducting membranes for hydrogen purification combined with low-temperature\ncondensation and phase separation of CO<sub>2</sub> from the retentate\ngas. This work presents results from 15 experiments for low-temperature\nphase separation and purification of CO<sub>2</sub> from five-component\nmixtures representative for retentate and tail gas compositions. The\nexperiments have been conducted with feed rates between 120 and 307\nkg/h and with CO<sub>2</sub> feed fractions between 56 and 82 mol\n%. The main separator pressures and temperatures range between 40\nand 70 bar, and −55 and −45 °C, respectively. Final\nCO<sub>2</sub> product purities up to 99.90 mol % have been measured.\nThe purity can be controlled through the pressure level in the flash\npurification separator and the temperature upstream of the inlet throttling\nvalve. Experiments and corresponding predictions based on GERG-2008\nand Peng–Robinson are generally consistent.