Performance Of Carbon Dioxide Absorption/Desorption In Tetramethylammonium Glycin Complex Solution

In recent years, the CO2emissions in China have kept increasing with the rapiddevelopment of the industrialization. The environmental problems caused by the majorgreenhouse gas have become more and more serious. Nowadays, the technologies ofcapturing carbon dioxide using aqueous organic amines and inorganic base solutionshave extensively carried out in the industrial applications. However, the technique hasmany disadvantages including high energy consumption of desorption, equipmentcorrosion, and environmental secondary pollution which is caused by the volatileorganics. Ionic liquids have been paid much attention. Extensive applications likesynthetic organic compounds, catalysis, separation, depuration and so on wereinvestigated. Research indicated that the absorbent mixed by ionic liquid absorbent andorganic amine solution could provide a wide range of physical and chemical properties.The functional ionic liquid-tetramethylammonium glycin ([N1111][Gly]) solutions weresynthesized by using the acid-base neutralization one-step method. Absorption anddesorption performances of carbon dioxide into the mixed aqueous solution ofmonoethanolamine (MEA) or Polyethylene glycol dimethyl ether(NHD) with[N1111][Gly] were investigated. The main research achievements are as following.(1)The functional ionic liquid-tetramethylammonium glycin ([N1111][Gly])solutions were synthesized by using the acid-base neutralization one-step method. Theionic liquid was characterized by the techniques of1H NMR, TGA, and FT-IR.Thecorrosion characteristics of mixed aqueous solution of MEA and [N1111][Gly] on carbonsteel was investigated by weight loss method combined with scanning electronmicroscopy(SEM). The obtained results indicated that the accession of [N1111][Gly] intoaqueous MEA could effectively restrain the corrosion on carbon steel sheets.(2)Absorption and desorption performances of carbon dioxide into the mixedaqueous solution of monoethanolamine (MEA) and [N1111][Gly] were investigated withdifferent proportion of [N1111][Gly] and MEA, temperature, pressure and stirring speed.The results indicated that the ionic liquid-[N1111][Gly] enhanced the absorption rate ofcarbon dioxide in MEA aqueous solutions. The maximal absorption rate and thesaturated absorption capacity of0.3mol L-1[N1111][Gly]+0.7mol L-1MEA aqueoussolutions were the highestin this work. With the increase of temperature, the carbon dioxide absorption rate increased. However, the saturated absorption capacity decreased.Increasing the gas pressure and rotate speed, the carbon dioxide absorption rate andsaturated absorption capacity both increased. In terms of properties of desorption, thesaturated absorbent optimum regeneration temperature for0.3mol L-1IL and0.7mol L-1MEA was393K, the best desorption time was2h. After five regenerationexperiments, the regeneration efficiency decreased by only2%.(3)Absorption and desorption of carbon dioxide into the mixed aqueous solution ofNHD and [N1111][Gly] were investigated with different proportion of [N1111][Gly] andNHD, temperature, pressure and stirring speed. The results indicated that the ionicliquid-[N1111][Gly] enhanced the absorption rate of carbon dioxide in NHD aqueoussolutions. The maximal absorption rate and the saturated absorption capacity of2mol L-1[N1111][Gly]-NHD aqueous solutions were higher than other solutions. The optimalabsorption temperature of the mixed absorbent was313K. Increasing the gas pressureand rotate speed, the carbon dioxide absorption rate and saturated absorption capacityincreased. The regeneration performance of the saturated absorbent under reducedpressure was superior than that under the atmospheric conditions. Regeneration timeswere almost without any effects of regeneration efficiency. The regeneration efficiencyblended solution was increased with the ion concentration in the NHD solvent.