Technical Research Based On Ionic Liquids For CO₂ Capturing

In recent years,as the increase of demand for fossil fuels and the consumption all over the world,the emission of CO2 also increased,and that resulted in a series of serious environmental problems,such as greenhouse effect,global warming and melting glaciers,et al.Therefore,it has the extremely great significance about how to effectively control the C02 emissions.Alconol-amine method is currently one of the most widely used and most mature technologies in industry,but this method also has some shortcomings:high volatile,the great solvent loss,high regeneration energy consumption,severe equipment corrosion,etc.Ionic liquids(ILs)can be used for CO2 capture and separation process because of its low volatility,great thermal stability,high solubility and selectivity with CO2.But the high viscosity of ionic liquids limits its application in the industry.This paper chose a mixture system of ionic liquids and solvents to absorb CO2,combining ionic liquid technology with alcohol amine process,making full use of their merits and remedies their defects,and explored an absorbent with good absorption capacity,high regeneration efficiency and low volatile.In this paper,two kinds of ionic liquids of amine-functionalized ionic liquid and similar ionic liquid were synthesized through one-step method.For amine-functionalized ionic liquid diethylenetriamine nitrate[DETA][NO3],diethylenetriamine acetate[DETA][AC];they were mixed with ME A,EG and H2O in different concentrations.We also synthesized four similar ionic liquid[BmimCl][MEA],[Bmimbr][MEA],[BmimCl][DEA],[Bmimbr][DEA],which were synthesized by ionic liquid[BmimCl]and[Bmimbr]with MEA,DEA in different mole ratio.We used them for C02 absorption experiment,and explored the influence of temperature,pressure,concentration,the type of ionic liquid,solvent type on the absorption capacity.The experimental results showed that the mixture of amine-functionalized ionic liquid and solvents with the mass ratio of 2:3 had the highest absorption capacity.For the similar ionic liquid,[bmimCl]and[bmimbr]mixtured with MEA/DEA in the mole ratio of 1:4 was the best.We also investigated that the type of ionic liquid with different solvent effect the absorption capacity with order[DETA][Ac]>[DETA][N03],BmimCl>Bmimbr.Amine-functionalized ionic liquid[DETA][Ac]and[DETA][NO3]with MEA had higher absorption capacity than EG and H20,the best capacity is 1.88 mol mol-1.The uptake of CO2 increased along with the increase in pressure.Increasing temperature can increase the reaction rate of absorption,but a high temperature also caused a decline in the uptake of carbon dioxide,but the impact wasn't obvious,so the system was stable.This paper investigated the regeneration performance of the mixed solution,and after four recycling,the absorption efficiency could reach 88%.In conclusion,ionic liquids are a kind of potential green solvent.