Development Of New Porous Materials And Their Adsorption Properties For Rare Gases

As a safe,clean and efficient energy source,nuclear energy is gradually becoming one of the main sources of human energy.However,spent fuel contains a lot of radioactive gases,such as Xe and Kr;on the other hand,people use Xe and Kr to separate and purify them,mainly by low temperature distillation,but this method requires a lot of energy.Studies have shown that another rare gas,Rn,is a carcinogen.Rn and its progeny will form radioactive aerosols in the air to contaminate the air.After breathing into the human body,people who breathe high Rn concentration of air for a long time may produce lung cancer.Therefore,it is of great significance to develop an economical and efficient material to adsorb Xe,Kr and Rn.In this work,the characteristics of COFs and PAFs materials such as porosity,high specific surface area,well-developed pore size distribution,and high stability are used to carry out rare gas adsorption experiments.The materials used were all synthesized by solvent ion calorimetry.After the samples were obtained,they were activated with methanol and dried,and then gas adsorption experiments were conducted.The Xe and Kr experiments are completed using BET operation,and Rn adopts the static adsorption method.Among them,the pore size distribution of COFs is relatively single,mainly in the range of micropores,and the pore size distribution of PAFs is very similar to activated carbon.In this paper,COF-300,COF-320,PPF-1 are selected,and L-5,PPP-2,PPP-3 and PPP-4 are developed on this basis.Gas adsorption experiments were carried out with seven materials.Studies have shown that under the conditions of 298 K and 1Bar,the maximum adsorption capacity of COF-300 for Xe reached 2.15 mmol/g.By fitting the adsorption data at low pressure,the separation ratio of Xe and Kr is 8.91.Under the same conditions,the maximum adsorption capacity of Xe of PPP-4 reached 2.32 mmol/g.By fitting the adsorption data under low pressure,the separation ratio of Xe and Kr is 11.21.At 273 K,the Rn adsorption coefficient of COF-320 reached 0.721 L/g;the Rn adsorption coefficient of PPP-3 reached 1.336 L/g.The new porous materials have great potential in the direction of gas adsorption.It also provides references for the preparation of COFs and PAFs materials.