Construction Of Hierarchical Porous Material Via Concentrated Emulsion Templating And Its Carbon Dioxide Adsorption Properties

Capturing the emitted CO2 gas is an effect way for soloving global warming that caused by greenhouse gas massive emitting.The porous material with high specific surface areas have been considered to have the potential to be high-effect CO2 absorbent.In this work,the hierarchical porous materials were obtained based on the interconnected-macroporous polymer prepared by concentrated emulsion template These materials showed good performance in CO2 capturing.The effects of micropores and funtional groups on CO2 capturing were investigated,and the absorbing mechanisms of these hierarchical porous materials were discussedHierarchical porous melamine resins(PFM)with hierarchical porous structures werer prepared in one step by using concentrated emulsion as template.To increase the specific surface areas of the prepared PFM,dimethyl sulfoxide(DMSO)was added in the continuous phase.DMSO would affect the polymerization induced phase separation that occured in the continuous phase of concentrated emulsion,which was critical for the formation of the pore structure in the PFMs.The effects of curing temperature,the mass ratio of DMSO to water in the continuous phase,and the mole ratio of formaldehyde to melamine on the macroporous morphologies and the textural properties of PFM were studied.The highest specific surface area of PFM could reach to 210 m2/g,and the nitrogen content of PFM was about 40 wt%.Because of the high specific surface area and rich nitrogen content,the CO2 adsorption capacity of the PFM could reach to 48.2 mg/g at 273 K and 1 bar.The nitrogen-containing hierarchical porous polymers(NHPPs),which possessed micropores,mesopores,and marcopores simultaneously,were constructed by introducing micropores and mesopores into polystyrene foam by post-crosslinking of the skeleton via Friedel-Crafts reaction.Firstly,polystyrene foams with abundant macropores(voids and windows)were obtained by concentrated emulsion polymerization.Subsequently,micropores and mesopores were generated by post-crosslinking cyanuric chloride into the skeleton of polystyrene foam.Cyanuric chloride was used as external crosslinker because of its rich nitrogen content.Finally,NHPPs with high specific surface areas(up to 1228 m2/g)were obtained.The effects of volume fraction of the dispersed phase in concentrated emulsion,DVB in polystyrene matrix,external crosslinker,and solvent on the textural properties of NHPPs were investigated.As CO2 absorbent,NHPP showed the maximum CO2 capacity as 88.2 mg/g at 298 K,1 bar and the good reproducibility.The relationship between the structures of NHPPs and the CO2 adsorption capacities were analyzed.The results indicated that the CO2 capacities showed best linear relationship with the microporous volume,and the nitrogen content also had correlation with the CO2 capacities.Furthermore,the tentative adsorption mechanism of triazine-ring in NHPPs to CO2 was proposed.Hierarchical porous carbons were obtained by carbonizing macroporous phenolic resin,which were prepared by using concentrated emulsion as template.There were micropores and macropores in the carbon materials,and the surfaces of the carbon materials were oxygen-rich.The effects of carbonizing temperature,volume fraction of dispersed phase in concentrated emulsion,,and concentration of monomer in the continuous phase in concentrated emulsion on the macroporous morphologies and textural properties of the hierarchical porous carbons were studied.As CO2 absorbent,the highest specific surface areas of the hierarchical porous carbons could reach to 2046 m2/g,with the total pore volume as 1.034 cm3/g.Under the conditions of 273 K and 1 bar,the highest CO2 capacites of the carbon material could be.up to 271 mg/g.Moreover,By comparing the CO2 absorbing speed of the carbons,it is considered that the macropores in the carbons would benefit for the rapid C02 capturing.