Multicomponent adsorptive separation of CO2, CH4, N2, and H2 over M-MOF-74 and AX-21@M-MOF-74 composite adsorbents

To develop an efficient hydrogen purification adsorbent, M-MOF-74 (M = Mg, Co, Ni, Zn and Cu) was synthesized by hydrothermal method, and super activated carbon (AX-21) was incorporated to form a new type of porous material for H2 purification from COG. Prepared samples were characterized by physical and structural properties and then compared by adsorption equilibrium. The dynamic adsorption performance of the materials during H2 purification was comprehensively evaluated by binary, multi-component measurements and multi-component breakthrough profiles. Adsorption isotherms were used to estimate selectivity values for CO2/H2, CH4/H2, N2/H2 and (CO2 + CH4 + N2)/H2. The results show that Mg-MOF-74 has the largest selectivity value among M-MOF-74. AX-Mg-MOF-74 incorporated with AX-21 at a mass ratio of 0.15 exhibited an average 30.88% increase in CO2, CH4, N2 and H2 adsorption capacity compared to pure Mg-MOF-74. In addition, the mean selectivity values for CO2/H2, CH4/H2, N2/H2 and (CO2 + CH4 + N2)/H2 are increased by 8.3%, 6.8%, 47.7% and 11.0% respectively.