Development of a Semiautomated Zero Length Column Technique for Carbon Capture Applications: Study of Diffusion Behavior of CO2 in MOFs

A semiautomated zero length column (ZLC) technique has been applied to investigate diffusion behavior of CO2 in metal organic framework Co/DOBDC powder and in Ni/DOBDC pellets. For Co/DOBDC crystals, since the system was close to equilibrium control even at the highest flow rate achievable in the ZLC, a lower limit of the micropore diffusivity was estimated, which indicates that for this MOF topology in conditions that are characteristic of practical carbon capture applications the process would be macropore diffusion controlled. This was confirmed on formed samples of Ni/DOBDC pellets for which experimental proof of the prevailing mass transfer resistance was obtained by performing ZLC experiments with different carrier gases. The kinetic experiments were used to determine void fraction and tortuosity values for the pellets.