The Performance Of Novel Tertiary Amines Solution On The CO₂ Capture

With the rapid development of global economies as well as population growth,the consumptions of fossil fuels have been found to increase significantly.As a result,there has been a corresponding sharp increase in the release of carbon dioxide（CO₂）,a major greenhouse gas（GHG）,to the atmosphere which is blamed as the chief culprit of global warming and climate change problems.The absorption using a chemical solvent is considered as one of the most promising technologies due to its maturity,cost effectiveness,and capability of handling a large amount of exhaust streams.One of the most pivotal points of this technology is to use a highly effective solvent.4-diethylamine-2-butanol（DEAB）,1-Diethylamino-2-Propanol（1DEA2P）,1-（2-Hydroxyethyl）-piperidin（1-（2-HE）PP）and1-（2-Hydroxyethyl）pyrrolidine（1-（2-HE）PRLD）are new solvents.CO₂ absorption performance is one of the key factors for evaluating the potential of those solvents that can be used for removing CO₂.In this work,the CO₂ absorption performance for DEAB,1DEA2P and 1-（2-HE）PP,1-（2-HE）PRLD were presented in terms of pKa,ions speciations plots,CO₂ equilibrium solubility,CO₂ absorption heat,and CO₂ absorption kinetics.Irn addition,the comparison of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD with the commercial conventional amine（e.g.MEA,MDEA）was presented in this work.The pKa of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD was experimentally measured as function of temperature.The correlations of pKa for those novel tertiary amines were developed in order to predicate the pKa for those amines.It was found that those correlation could predicate the pKa values for DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD very well.In order to comprehensively understand the process of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD absorption CO₂ and provide the more information to develop the VLE model,the ions（amine,amineH+,HCO3-,CO32-）speciation plots of systems for DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD absorption CO₂ were developed using the pH method.In addition,the relationship of ions（amine,amineH+,HCO3-,CO32-）and pH values for DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD were developed in this work.The relationship of ions（amine,amineH+,HCO3-,CO3-）and pH values and temperature for DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD were presented in order to predicate the ions concentrations.The equilibrium solubility of CO₂ in 2mol/L DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD were measured over the temperature range from 298 to 333K and CO₂ partial pressure range from 8 tolOlkPa.The results shows that CO₂ equilibrium solubility in DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD aqueous solution increases as function of CO₂ partial pressure and decreases as function of temperature.In this work,the heat（△Ha）of CO₂ absorption in aqueous DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD was estimated to be-41.4 kJ/mol,-43.6 kJ/mol,-34 kJ/mol and-34.2kJ/mol by using the Gibbs-Helmholtz equation,respectively.In this work,a stopped-flow apparatus was used to measure the kinetics of CO₂ absorption into aqueous solution of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD in terms of observed pseudo-first-order rate constant（k0）and second order reaction rate constant（k2）.The experiments were conducted over a concentration range of 100-900 mol/m3,and a temperature range of 298-313 K for DEAB,a concentration range of 120-751 mol/m3;and a temperature range of 298-313 K for 1DEA2P,a concentration range of 200-1000 mol/m3,and a temperature range of 298-313 K for 1-（2-HE）PP,a concentration range of 200-1000 mol/m3,and a temperature range of 298-313 K for 1-（2-HE）PRLD.The Arrhenius equation of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PRLD were obtained in this work,which could be used to represent the experimental values.It was found that the calculated values were in a good accordance with experimental values with an acceptable AADs of 5.8%for DEAB,8.0%for 1DEA2P,8.3%for 1-（2-HE）PP,6.1%for 1-（2-HE）PRLD.The comparison DEAB,1DEA2P,1-（2-HE）PP,1-（2-HE）PRLD with MEA,MDEA in terms of CO₂ equilibrium solubility,CO₂ absorption heat,CO₂ absorption kinetics was presented in this work,which could provide the useful information about the possibility of DEAB,1DEA2P,1-（2-HE）PP and 1-（2-HE）PP as potential solvents for CO₂ capture.The comparison shows that those four novel solvents exhibit the good performance of CO₂ capture,which could be consider the alternative solvents for CO₂ capture.