| Under the large demand of carbon dioxide(CO2)separation and capture in chemical,metallurgy,energy and other industries,it is urgent to develop novel and high efficiency CO2 separation technologies.Compared with the chemical absorption technology of liquid amine,the chemical adsorption technology of amine functionalized materials have the advantages of low energy consumption,simple preparation process and no equipment corrosion.However,it has several disadvantages:low adsorption capacity,insufficient abrasion resistance and poor cycling stability.In this paper,studies on CO2 adsorption by amine functionalized materials were carried out,and porous organic composites with polyacrylate and polyacrylamide as carriers and polyethyleneimine(PEI)as adsorption active components were prepared by emulsion polymerization.The main research contents are as follows:(1)The spherical porous skeleton materials with ordered pore structure were synthesized by suspension polymerization of water-in-oil(W/O)and oil-in-water(O/W)emulsion with glycidyl methacrylate and acrylamide,respectively.For polyacrylate skeleton material,the water absorption is 4.07 wt.%,and the attrition rate is 0.50 wt.%·h-1.For polyacrylamide skeleton material,the water absorption is 5.22 wt.%,and the attrition rate is 0.35 wt.%·h-1.For polyacrylate-based materials and polyacrylamide-based materials after loading 60 wt.%of PEI,the adsoption capacity are 3.35 mmol·g-1 and 3.56 mmol·g-1,and the capacity loss rate for 50 cycles are 25.7%and 39.0%,respectively.It indicates that the porous polymer materials can meet the requirement of PEI load but their cycling stability need to be further improved.(2)The poly(acrylamide-(N,N'-methylene-bisacrylamide))(PAM)spherical matrix was prepared by O/W emulsion polymerization and impregnated in 1,2-epoxyhexane(EH)functionalized PEI.After PEI modified by EH,the primary amine is converted to secondary amine in the PEI molecular chain.The modified PEI has many excellent properties,as follows:the optimal adsorption and desorption temperature decrease to 50? and 125?,respectively,the adsorption capacity is 2.93 mmol·g-1,the isosteric heat is 56.8 kJ·mol-1 and the renewable energy consumption is 2.2 MJ·kg-1(CO2).In addition,the times to achieve the 90%CO2 adsorption and desorption capaity are 10 min and 11 min,respectively.After 50 adsorption/desorption cycles,the loss rate of adsorption capacity of the material is 9.2%,indicating that the cycling stability of the materials are significantly improved.However,modified PEI is costly and increases the complexity of the process,which is unsuitable for large scale industrial production.(3)A PEI embed and graft loading method was used to synthesize a new material by the acrylate W/O emulsion polymerization.In the emulsion,PEI were dissolved in water phase and enveloped into the oil phase with glycidyl methacrylate(GMA)and trimethylolpropane triacrylate(TMPTA).The PEI loading method can directly contact the amine group with the epoxy group and promote the graft reaction.The ring-opening reaction degree of the epoxy group is 41.0%.Moreover,the water contact angle is 101.00 and the water absorption is 1.46 wt.%at 85?.The optimal PEI loading weight is 40 wt.%,the adsorption temperature is 85?,the adsorption capacity is 2.66 mmol·g-1,the adsorption selectivity is 601,the purity of captured CO2 is 98.8%,the isosteric heat is 58.75 kJ·mol-1,and the calculated energy consumption is 2.30 MJ·kg-1(CO2).The times to achieve the 90%CO2 adsorption and desorption capaity are 8.5 min and 6.5 min at 650 and 85?,respectively.In addition,the test of urea-resistance shows that,the loss rate of the adsorption capacity is only 1.8%after 50 adsorption/desorption cycles,and the material has good urea-resistance performance.In the first 6 oxidation adsorption/desorption cycles,the decrease rate of adsorption capacity is 11.2%,and in the last 14 adsorption/desorption cycles,the decrease rate of adsorption capacity is only 3.9%.(4)Acrylate copolymer composites were prepared by W/O emulsion suspension polymerization with GMA,tert-butyl methacrylate(TBMA)and TMPTA.The chelator trisodiumphosphate(TSP)and PEI were dissolved in the aqueous phase of emulsion.After emulsion polymerization,PEI molecules are firmly loaded into the polymer matrix by chemical grafting and physical embedding,which can enhance the chelating effect of TSP and metal ions(Fe and Cu).After addition of chelating agent,at high temperature(120?)and long-term exposure in the air to make samples fully oxidized.The adsorption capacity loss rate decrease from 39%to 25%,and the oxidation resistance of the materials are improved obviously.(5)The optimum preparation condition and method of materials on a large scale were determined by kilogram-scale-up experiment and the products with good pore structure were obtained.In addition,it is found that the toth isothermal adsorption model can well describe the process of CO2 isothermal adsorption by amine functionalized material.The fractional order rate equation can be used to describe the dynamic characteristics of CO2 adsorption.The adsorption/desorption performance and abrasion resistance of the material prepared on a large scale were tested in a small fluidized bed with simulated gas adsorption and nitrogen desorption.It is found that the adsorption and desorption process can be completed within 7 min and 10 min,respectively.After 20 adsorption/desorption cycles,material quality loss rate is 0.28 wt.%·h-1 and adsorption capacity loss rate is 3.75%.The results indicate that the material has good adsorption/desorption capacity,high reaction rate,thermal stability,resistance to oxidation and urea formation,good abrasion resistance,and high cycling stability.It lays a good foundation for CO2 adsorption and separation in fluidized bed. |
PDF Full Text Request