Preferential CO2 adsorption over cadmium-based Porous Metal-organic Framework

Novel preferential carbon-dioxide sorption was observed on a cadmium based mixed-linker metal-organic framework (MOF){[Cd(abdc)(azpy)](DMA)}(n) [where 4,4 & PRIME;-azopyridine = azpy and 2-amino-1,4-benzenedicarboxylic acid = H(2)abdc]. {[Cd(abdc)(azpy)](DMA)}(n) features an interpenetrated 3D networked structure consist of pendant Lewis basic -NH2 groups directed towards the pores. PLATON analysis shows that the solvent accessible void space of the MOF is ca. 26.6%. At 298 K, the desolvated MOF showed an uptake of carbon-dioxide of 8.33 wt% or 42.42 cc/g at 1 bar pressure which, upon cooling to 273 K, is increased to about 12.17 wt% or 62 cc/g at 1 bar pressure. In contrast, methane uptake capacities of the desolavated MOF were 0.127 wt% or 1.79 cm(3)/g and 1.34 wt% or 18.74 cm(3)/g at the adsorbate pressure of 1 bar at 298 K and 273 K, respectively. On the otherhand, hydrogen uptake capacity of the desolavated MOF reached to 0.31 wt% or 34.87 cm(3)/g at the adsorbate pressure of 1 bar at 77 K. Selectivity of carbon-dioxide with respect to methane at 273 K is calculated to be 5.4. The heat of adsorption for carbon-dioxide is calculated to be 38 kJmol(- 1).