Synthesis And Characterization Of Two GrO@MOF Composites And Their CO₂/CH₄ Adsorption Selectivity

The international community is facing two major problems of the global climate change and energy crisis. Separation of CO2 and CH4 from biomethane, and the application of CH4 in the energy industry are of great significance to solve the above problems. This dissertation focuses on synthesis of Gr O@MOFs and their adsorption separation towards CO2/CH4. Graphene Oxide(Gr O) was introduced into two MOFs which have advantage in adsorption at low pressure and medium pressure respectively.(1) Gr O@Cu-BTC composites were synthesized successfully. The 1Gr O@Cu-BTC has the highest BET specific surface area and pore volume(1437 m2/g and 0.70 cm3/g respectively, both increased by 23% than the parent Cu-BTC); Its thermal stability enhanced slightly than the parent material; SEM and TEM images display its rigid sheet structure with Gr O-MOF alternating.(2) The CO2 capacity of 1Gr O@Cu-BTC at 273 K, 1 bar is 8.19 mmol/g, increases by 26 % than the parent Cu-BTC. It also present excellent regeneration performance; For the equimol mixture of CO2 and CH4, the selectivity calculated with IAST model is up to 14, almost twice of that of the parent Cu-BTC; Interation with CO2 of the 1Gr O@Cu-BTC is stronger than that of the parent Cu-BTC.(3) Gr O@MIL-53(Cr) composites were synthesized successfully by the first time. The 1Gr O@MIL-53(Cr) has the highest BET specific surface area(1370 m2/g), and 10 Gr O@MIL-53(Cr) has the highest total pore volume(0.57 cm3/g). SEM and TEM images display that 1Gr O@MIL-53(Cr) with low Gr O content have thinner and uniformer sheets than 10 Gr O@MIL-53(Cr).(4) The breathing phenomina disappears with the increase of Gr O content. At 5 bar, CO2 capacity of the 10 Gr O@MIL-53(Cr) increases by 54 % than the parent MIL-53(Cr). At 25 bar CO2 capacity of the 1Gr O@MIL-53(Cr) increases by 27 % than that of the parent MIL-53(Cr); Further, the Gr O@MIL-53(Cr) composites have stronger interation with CO2 with th more Gr O content.(5) The crystal structure of 1Gr O@Cu-BTC collapsed after being immersed in 323 K water for 7 hours; However, 1Gr O@ MIL-53(Cr) maintains intact crystal structure after being immersed in 323 K water for 7 days.