Preparation,modification And Adsorption Properties Of Novel Copper Silica Molecular Sieves

In recent years,due to the rapid development of industry,a large number of fossil fuel combustion,resulting in a sharp increase in the content of CO2 in the air,leading to serious environmental problems,sohow to reduce CO2 emissionshas become the focus of research.Because of the advanta ges of low energy consumption,good circulation effect and high product purity,PSA has shown great advantages in the field of CO2 separation.The core of PSA is adsorbent.Heteroatom molecular sieves are good adsorbents for CO2 capture.Among them,Copper Silica molecular sieveshave the advantages of fast adsorption rate,good selective adsorption performance and good thermal stability of framework structure.However,in recent years,there are few researches on Copper Silica molecular sieves applied in the adsorption field.Therefore,it is necessary to develop a new type of Copper Silica molecular sieve for adsorption.In this experiment,the synthesis process of the new type of Copper Silica molecular sieve is studied,and the influence of different factors on the final sample is studied.Finally,a better synthesis method is obtained.Then the synthesized samples were characterized and analyzed and gas adsorption performance was tested.Finally,the samples were exchanged and the characteristics of the samples after ion exchange and the adsorption properties of the samples after ion exchange were studied.In this experiment,sodium silicate solution was used as silicon source,copper sulfate solution as copper source,and hydrothermal reaction was carried out in the reactor to synthesize a new type of copper silicon molecular sieve.The effects of pH value,crystallization temperature,crystallization time,the molar ratio of silicon to copper and the amount of alkali metal inor ganic salt on the synthesis of samples were investi gated.The results showed that in the environment of ph 13.5,the molar ratio of silicon to copper was 5.8,the amount of alkali metal inor ganic salt KCl was 6 g,and the samples with the best crystallization degree could be obtained by one day crystallization in the reactor with crystallization temperature of 215℃,A more mature synthesis method was obtained.The results show that the synthesized sampleshave good crystallinity,almost no impurities,the main elements are silicon and copper,and the specific surface area is 103m2/g.The results show that the equilibrium adsorption capacity of carbon dioxide is 12.15 cm3/g,10.7 cm3/g and 8.86 cm3/g at 273k,303k and 333k.At 273k,303k and 333k,the equilibrium adsorption capacity of nitrogen is 3.46 cm3/g,3.25 cm3/g and 2.6 cm3/g,and the adsorption isotherms of nitrogen and carbon dioxide conform to the basic law.The samples were modified by Li+,Zn2+and CS+,and the optimal concentration,temperature and time of modification were explored.The modified samples were characterized and analyzed.It was found that the original chemical bonds and functional groups of the samples were not changed by the modification,and there were modified ions in the modified samples,indicatin g that the ion exchange was successful.The optimum conditions of lithium ion modification are:ion exchange solution concentration is 0.1 mol/L,exchange temperature is 25℃,exchange time is 8h.The samples were modified by Li+,Zn2+ and CS+,and the optimal concentration,temperature and time of modification were explored.The modified samples were characterized and analyzed.It was found that the original chemical bonds and functional groups of the samples were not changed by the modification,and there were modified ions in the modified samples,indicating that the ion exchange was successful.The optimum conditions of lithium ion modification are:ion exchange solution concentration is 0.1 mol/L,exchange temperature is 25℃,exchange time is 8h.The optimum conditions of zinc ion modification are as follows:the concentration of ion exchange solution is 0.1 mol/L,the exchange temperature is 25℃,and the exchange time is 8h.The optimum conditions of cesium ion modification are as follows:the concentration of ion exchange solution is 0.005 mol/L,the exchange temperature is 25℃,and the exchange time is 1h.The adsorption capacity of the samples after ion exchange was 13.93 cm3/g,which was 24%higher than that of the original samples.The adsorption capacity of the sample after zinc ion exchange can reach 15.63 cm3/g,which is 46%higher than that of the original sample.After cesium ion exchange,the adsorption capacity of the sample can reach 14.17 cm3/g,which is 37%higher than that of the original sample.