Study On Absorption Of CO₂ In Flues Into Aqueous Solutions Of DETA/TETA

Absorption of CO2 with amines has been extensively studied in recent years because of the environmental concern of greenhouse effect and CO2 enhanced oil recovery (EOR) applications ?Features of single amine solutions of DETA , TETA and mixed amine systems, absorption mechanism were studied in this paper, which may serve future study as groundwork.Using absorber bottle and heater, absorption effects and regeneration efficiencies of gaseous CO2 in flues into single solutions of DETA and TETA, aqueous mixtures of MDEA with DETA and TETA were conducted. Absorption rates and capacities of fresh solutions, regeneration temperature and time of saturated solutions were measured. Experimental results showed that the absorption rate and capacity of CO2 could be remarkably enhanced by the mixed system of DETA/TETA + MDEA. It was concluded that aqueous solution of 0.2mol/L DETA /TETA+0.8mol/L MDEA was fitted for industry.Reaction mechanism of CO2 and amines was discussed. This process was studied in a stirred-cell absorber. Concentration and temperature affect absorption. Kinetics region were confirmed: absorption of CO2 into single DETA or TETA was fast reaction, and that into aqueous mixtures according to pseudo first order reaction. Based on experiment results and theoretical calculations, fitting curves of reaction speed constants and concentrations were:kcat=0.20-e DETA . kcat=0.30-e DETA .Second functions of enhancement factors and concentrations were: E = 1.57 +11,67CDETA - 5.7CDETA2; E = 1.85 + 8.89CTETA -0.18CTETA2.The prediction of enhancement factor was described for simplified film theory for CO2 absorption with MEA+MDEA. It has been demonstrated that there were mutual effects in chemist reactions because of the difference between theory and experiment results. And the mutual coefficient P for the mixed MDEA and MEA was obtained as a function of CO2 loading L(total concentration: 2.0mol/L, MDEA concentration: 0.3~0.5mol/L): B = B(L) = 0.12 +0.35-e-L/0.026.