Study On Functionalized Modification And CO₂ Adsorption Of MOF-74@GO Composites

Alleviating the CO₂emissions from fossil fuel combustion is crucial for addressing the increasingly severe climate issues.Adsorption technology,which employs porous materials as the core application,has great potential in the field of CO₂capture.Developing high-capacity and thermally stable adsorbent materials,as well as efficient material preparation processes,is an important research direction in the field of adsorption technology.To address the instability of the Metal-Organic Frameworks（MOFs）material structure and low CO₂adsorption performance at high temperatures,the modifiability of MOFs materials was utilized.Using a one-pot solvothermal synthesis,graphene oxide（GO）and organic amine-loaded MOF-74composite materials were prepared,and the optimal process conditions were obtained through in-situ modification.Based on this,CO₂adsorption equilibrium and kinetics were characterized and evaluated by functionalizing the optimized solid adsorbent MOF-74@GO with multiple functional groups.The main research conclusions are as follows:（1）MOF-74 crystals were grown in-situ on GO by the solvothermal synthesis.MOF-74@GO composites were prepared.The MOF-74@GO-3 with porous structure was successfully prepared by coordination of metal ions with oxygen-containing groups in the GO structure when the GO addition was 0.3%.The results showed that its thermal decomposition temperature was 393℃and CO₂adsorption capacity was 113.39 cm³/g,which was 23.12%higher than that of the parent MOF-74.（2）Three amino modifiers,Triethylamine（TEA）,Tetraethylenepentamine（TEPA）and Polyethyleneimine（PEI）,were selected for post-synthesis modification of Mg-MOF-74crystals.The results showed that the different structures of the amino modifiers had effects on the CO₂capture performance,and the adsorption amount decreased with the increase of the organic amine loading.The primary and secondary amine（TEPA and PEI）groups showed better CO₂capture ability than the tertiary amine（TEA）group,while the adsorption performance of the TEPA modification was stronger than that of the PEI modification.Among them,when the TEPA addition was 30%,its thermal decomposition temperature was 376℃and CO₂adsorption capacity was 119.96 cm³/g,which was 30.25%higher than that of the parent MOF-74.（3）A bifunctionalized MOF-74 structure with both GO and amino groups was constructed by introducing polar functional groups with strong interaction with CO₂molecules in MOF-74 through direct synthesis and post-modification.The results showed that the co-modification of GO and TEPA facilitated the formation of porous structure and improved the thermal stability and CO₂adsorption performance of MOF-74.Its thermal decomposition temperature was 382℃and CO₂adsorption capacity was 129.42 cm³/g,which was 40.52%higher than that of the parent MOF-74.The potential interaction study between the adsorbent and the framework showed that the adsorption isotherm of CO₂by TEPA-MOF-74@GO was consistent with both Langmuir and Freundlich models,and the adsorption process was consistent with the Pseudo-second-order-model.