In the global transition towards a sustainable low-carbon economy, achieving a balance between high adsorption capacity and long-term stability of the adsorbent is crucial. In this study, MFM-136 with Kagome configuration was selected as the research object. The structure of MFM-136 was analyzed by XRD, BET, FT-IR, TG and SEM. The CO2 adsorption performance of MFM-136 was investigated by a series of gas adsorption experiments. The competitive adsorption relationship between impurity gas and CO2 was further identified by CO2 breakthrough experiment and in situ DRIFTS experiment, and revealed the co-adsorption mechanism of impurity gas and CO2 on MFM-136 surface. The adsorption experiment results showed that the adsorption capacity of MFM-136 for CO2 and H2O at 298 K was 3.0 and 11.94 mmol/g, respectively. The micro pore size (0.59 nm) of MFM-136 and the multiple adsorption sites in its skeleton enabled MFM-136 to selectively adsorption CO2 at room temperature. The adsorption selectivity of CO2/N2 reached 24 at 298 K, the Qst reached 23 kJ/mol, and the adsorption capacity was completely regenerated after degassing at 120℃ for 30 min. The results of breakthrough experiment and in situ DRIFTS experiment showed that the O2 promoted the chemisorption of CO2. The chemisorption of SO2 mainly occurs on the surface of the adsorbent to form sulfate and sulfite. Under O2-containing conditions, NO will react with O2 to form NO2, which will generate strong chemisorption on the surface of the adsorbent and generate corresponding nitrate and nitrite species. The water vapor not only promotes the chemical adsorption of CO2 and the production of bicarbonate, but also promotes the competitive adsorption between CO2 and SO2, NO.