Preparation And Adsorption Properties Of Nitrogen-Rich Porous Carbon

Volatile Organic Compounds（VOCs）from a wide range of sources,have great harm to environment and human health.Porous carbon material has the advantages of low preparation cost,environmental friendliness,recyclability and so on,which is a very potential adsorption material for VOCs removal.Nitrogen-doping provides more VOCs adsorption active sites,which is conducive to improve the adsorption performance.The purpose of this paper includes two aspects,on the one hand,new activators were studied to improve the nitrogen doping amount of porous carbon materials.On the other hand,the method of changing the pore structure of porous carbon materials under the premise of high nitrogen doping amount is explored.It mainly includes the following contents:1.A novel high nitrogen-doping porous carbon microsphere was prepared by one-step carbonization activation using melamine cyanurate and soybean powder as the precursor and CuCl₂as the activator.The carbon microspheres have large specific surface area and high nitrogen-doping level.By studying the influence of the mass ratio of precursor to activator and carbonization temperature,it was proved that when the mass ratio of precursor to CuCl₂was 4,the specific surface area(1672 m²g^-1)of the product was the largest,and the N doping level（13.09 at%）was also higher than that of the control group without activator.It is also proved that the product retains the spherical shape and layered porous structure similar to the original structure of the precursor due to the mild REDOX reaction between the carbon matrix and CuCl₂.2.The adsorption properties of porous carbon samples derived from melamine cyanurate to weakly polar gases（toluene and xylene）and polar gases（acetone and methanol）at 25℃ were tested by static adsorption system,and simulated by GCMC and DFT,proving that the adsorption of weak polar gas by porous carbon depends mainly on its specific surface area and has no obvious relationship with nitrogen content.The saturated adsorption capacity of porous carbon for polar gas is mainly determined by the volume of micropore and mesopore of adsorbent,and the adsorption capacity per unit specific surface area is positively correlated with the nitrogen content.3.A reasonably designed polyimide precursor was synthesized by changing the ratio of urea to thiourea in the precursor,and then nitrogen-rich porous carbon with high surface area and adjustable pore size distribution was prepared by mild activation of copper chloride at 800℃.It is proved that increasing the proportion of urea can increase the volume of mesopore while keeping the original micropore structure,and the content of heteroatoms also increases slightly.The prepared graded porous carbons have very high surface area,large mesopore volume and rich nitrogen content,excellent static acetone adsorption properties of 768mg g^-1（25℃）and 799mg g^-1（15℃）,high dynamic acetone capture capacity and fast transfer rate.