H2 PSA purifier for CO removal from hydrogen mixtures

A two-bed PSA purifier was developed to produce high purity hydrogen for fuel cell applications. Two types of hydrogen-rich mixtures produced from coal off-gas were used. Feed 1 consisted of a 99% H2 mixture (H2:CO:CO2:N2 = 99:0.1:0.05:0.85 vol.%) containing 0.1% CO while Feed 2 was a 95% H2 mixture (H2:CO:CO2:CH4:N2 = 95:0.3:0.1:0.05:4.55 vol.%) containing 0.3% CO. An increase in the P/F ratio and adsorption pressure led to an almost linear decrease in H2 recovery with increasing purity. However, a sharp drop in CO concentration occurred at a specific operating range in both feeds. The feed was purified to 1.1 ppm CO with 99.99+% H2 purity and 80.0% recovery under 6.5 bar and 0.15 P/F ratio while CO in Feed 2 could be reduced to 6.7 ppm with 99.96% H2 purity and 78.4% recovery. The PVSA process, which combined vacuum and purge steps, could improve recovery by about 10% compared to the PSA process.