The adsorption equilibrium of carbon
dioxide (CO<sub>2</sub>),
carbon monoxide (CO), nitrogen (N<sub>2</sub>), methane (CH<sub>4</sub>), and hydrogen (H<sub>2</sub>) was studied at 303, 323, and 343
K and pressures up to 7 bar in titanium-based metal–organic
framework (MOF) granulates, amino-functionalized titanium terephthalate
MIL-125(Ti)_NH<sub>2</sub>. The affinity of the different adsorbates
toward the adsorbent presented the following order: CO<sub>2</sub> > CH<sub>4</sub> > CO > N<sub>2</sub> > H<sub>2</sub>, from the
most adsorbed to the least adsorbed component. Subsequently, adsorption
kinetics and multicomponent adsorption equilibrium were studied by
means of single, binary, and ternary breakthrough curves at 323 K
and 4.5 bar with different feed mixtures. Both studies are complementary
and aim the syngas purification for two different applications, hydrogen
production and H<sub>2</sub>/CO composition adjustment, to be used
as feed in the Fischer–Tropsch processes. The isosteric heats
were calculated from the adsorption equilibrium isotherms and are
21.9 kJ mol<sup>–1</sup> for CO<sub>2</sub>, 14.6 kJ mol<sup>–1</sup> for CH<sub>4</sub>, 13.4 kJ mol<sup>–1</sup> for CO, and 11.7 kJ mol<sup>–1</sup> for N<sub>2</sub>. In
the overall pressure and temperature range, the adsorption equilibrium
isotherms were well-regressed against the Langmuir model. The multicomponent
breakthrough experimental results allowed for validation of the adsorption
equilibrium predicted by the multicomponent extension of the Langmuir
isotherm and validation of the fixed-bed mathematical model. To conclude,
two pressure swing adsorption (PSA) cycles were designed and performed
experimentally, one for hydrogen purification from a 30/70% CO<sub>2</sub>/H<sub>2</sub> mixture (hydrogen purity was 100% with a recovery
of 23.5%) and a second PSA cycle to obtain a light product with a
H<sub>2</sub>/CO ratio between 2.2 and 2.4 to feed to Fischer–Tropsch
processes. The experimental cycle produced a light stream with a H<sub>2</sub>/CO ratio of 2.3 and a CO<sub>2</sub>-enriched stream with
86.6% purity as a heavy product. The CO<sub>2</sub> recovery was 93.5%
