Synthesis And Properties Of Polyacrylamide Porous Beads For CO₂ Adsorption

CO2 emission from the fossil-fuel power station is the main emission source of the greenhouse gas.In order to achieve the goal of efficient CO2 emission reduction,it is of great significance to further develop carbon capture technology for fossil-fuel power and develop low-temperature solid adsorbents with low cost and excellent overall performance.Due to the weak chemical reaction between the amine group and the CO2 molecule,the amine-based adsorbent has the potential for low-energy regeneration while possessing good adsorption performance.In this paper,AM is used as the monomer and MBA is used as the cross-linking agent.This dissertation is aimed to develop spherical solid amine adsorbents that can be used in fluidized bed processes based on O1/W/O2 multi-emulsion polymerization method,combing with morphology control,structure optimization,nano-enhancement,and interface modification.The main contents are as follows:(1)Optimizing the macroporous structure of acrylamide oil-in-water(W/O)high enternal phase emulsion polymers(polyHIPE).The synergistic effect of complex emulsifiers and high-speed shearing resulted in an oil-in-water polyHIPE with regular pore structure,small pore size,and uniform distribution.The influencing factors of preparation of polyHIPE beads by O1/W/O2 multiple emulsions were explored.The third phase(O2),which has a lower surface tension,a density close to that of the emulsion droplets,and a relatively high viscosity,will favor the formation of monodisperse spherical emulsion droplets in the third phase of the O1/W concentrated emulsion emulsion.The rapid polymerization rate and the appropriate polymerization temperature enable monodispersed emulsion droplets polymerization rapidly and stably in the third phase.Adjusting the appropriate emulsion viscosity to ensure the pore structure and pore size distribution and high sphericity,while increasing the volume fraction of the dispersed phase as much as possible is a key factor in the preparation of highly efficient spherical solid amine adsorption materials.(2)Firstly,The nano-enhanced monodisperse polyHIPE beads have been successfully synthesized by the combination of precipitation polymerization and concentrated emulsion polymerization to form an O1/W/O2 multiple emulsion system.During the preparation of the adsorbent matrix,the volatile toluene was used as the dispersed phase,and the volume of the dispersed phase was up to 83.5 v.%under the premise of ensuring the sphericity.Then,the enhancement effect of nano-particles on the matrix material was investigated.The crushing strength of nano-TiO2 becaming 33.43 N(increased by 56%)after 1.5 wt.%nano-TiO2 was added.After the PEI was loaded,the polyHIPE beads with a loading of 60wt.%exhibited good CO2 adsorption performance.The adsorption amount can reach 3.75 mmol/g under pure CO2 conditions at 110 ?,and the time for the sample to reach 90%CO2 adsorption(2.79 mmol/g)under simulated flue gas conditions and complete CO2 desorption under pure CO,was 10 minutes and 15 minutes,respectively.The sample also has good stability after 50 adsorption/desorption cycles(dropping by about 7.59%).(3)The introduction of reversed-phase suspension polymerization makes it possible to prepare monodisperse polyHIPE beads with a smaller particle size,while the reversed-phase suspension polymerization method can shorten the preparation cycle of the adsorbent products,and have the potential for industrial amplification.A preliminary scale-up preparation has now been achieved,with an average productivity of 94.7 wt.%.Through thermodynamic and kinetic tests the material has presented content CO2 capacity of 3.38 mmol/g at 110 °C,rapid adsoiption/desorption within 9 nin,good stability after 50 adsorption and desorption cycles(dropping by about 8.43%).(4)The effects of three different molecular weight industrial grade PEIs as amines were compared,and a further stability test was performed on AM-PEI2000,a sample made of PEI(MS=2000,T.P.)as an amine.The results show that the sample has no obvious mass reduction at the actual desorption temperature of 140 ?,and no side reactions occur except for adsorption after adsorption and desorption.The wear rates of the products in the cold and thermal state at 25 ? and at 130 ? are Ic=0.21 wt.%/h,Ih?0.33 wt.%/h respectively.