A Study of Oxidative Degradation of AMP for Post-combustion CO2 Capture

Transcription

1 A Study of Oxidative Degradation of AMP for Post-combustion CO2 Capture Tielin Wang, Chen Chen, Klaus-J.Jens Telemark Technological R & D Institute, Porsgrunn, Norway Telemark University College, Porsgrunn, Norway June 15, Trondheim

2 Outline Introduction Experimental Conditions Results Conclusion

3 Introduction Background The oxidative degradation mechanism of amines is unclear, even for the benchmark molecule MEA 2-amino-2-methyl-1-propanol (AMP) is claimed to offer advantages over the traditional amines Scope of the study Identification and quantification of the main degradation products Evaluation of the effects of the main operating parameters Proposition of the possible degradation pathways

4 Experimental Conditions Remaining AMP quantification Cation chromatography Degradation products identification/quantification Anion chromatography Gas chromatography-mass spectrometry (GC-MS) Fourier transform infrared spectroscopy (FT-IR)

5 Experimental Conditions Our Experimental Conditions 3-5mol/kg (50-70 ) bar O 2 (atmospheric pressure air) glass batch reactor

6 Comparison of degradation rates 70 Degradation rate/% MEA AMP DEA MDEA 5mol/kg amines degraded 16days at 120 with 350kPa O 2 Degra. Rate = (C0-C)/C0 The oxidative degradation rate of AMP was less than that of MEA, but was close to that of MDEA under our experimental conditions.

7 Thermal degradation AMP Concentration (mol/kg) C 140C 5 mol/kg AMP under nitrogen Reaction Time (h) The effect of thermal degradation of AMP is negligible (at least, <140 ).

8 Formation of oxazolidinone CH 3 AMP HO CH 2 C CH 3 NH 2 H AMP HO NH 2 CO 2 HO N H O O O H HN O H 2 O HO N O OH 4,4-dimethyl-2-oxazolidinone (a) Gas Chromatogram of AMP aqueous solution at the beginning of the experiment (0h) using 5mol/kg AMP at 120 with 250kPa O 2. (b) Chromatogram of a partially degraded AMP aqueous solution at the end of the experiment (384h).

9 The Effect of Initial Concentration 5,5 5,0 5mol/kg 3mol/kg AMP Concentration (mol/kg) 4,5 4,0 3,5 3,0 2,5 2,0 1, Reaction Time (h) AMP degraded under 250kPa O 2 and 120

10 70 The Effect of Temperature 5,5 5,0 AMP Conc. (mol/kg) 4,5 4,0 3,5 3,0 2,5 100C 120C 140C 2, Reacdtion Time (h) 5mol/kg AMP degraded with 250kPa O 2

11 The Effect of O2 Pressure 5,5 5,0 250 kpa 350 kpa AMP concentration (mol/kg) 4,5 4,0 3,5 3,0 2,5 Response 350kPa O 2 250kPa O 2 2, Reaction Time (h) 5mol/kg AMP degraded under O 2 at Retention Time/min Corresponding anion chromatograms

12 The Effect of Agitation Rate O 2 (gas) O 2 (Liquid) (React with AMP ) O2 mass transfer limited? 5,5 AMP Concentration (mol/kg) 5,0 4,5 4,0 3,5 3,0 2,5 0 RPM 500 RPM 1000RPM Peak Area (µs*min) Formate Acetate Oxalate Nitrite 2, Reaction Time (hr) Reaction Time (h) 5mol/kg AMP degraded at 120 and 250kPa O 2 Corresponding results of anions determination

13 The Effects of Metal Ions 5,2 AMP Concentration (mol/kg) 5,0 4,8 4,6 4,4 4,2 4,0 No metal ions 0.1mM FeC 2 O 4 0.1mM CuSO 4 5mol/kg AMP degraded by bubbling air at 50 (0.5Ln/min) 3, Reaction Time (hr) 5mol/kg AMP degraded at 120 and 250kPa O 2 Response Metal ions free + 0.1mM Fe(II) Retention Time/min Anion chromatograms

14 The Effect of Radical Initiator HO CH 2 C CH 3 NH2 CH 3 Initiation HO CH C CH 3 NH2 CH 3 O 2 HO CH C O O CH 3 NH2 CH 3 Products 5,5 5,0 4,5 AMP Conc. (mol/kg) 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 Without Persulfate + 7.5g/L Potassium Persulfate 0, Time (h) 5mol/kg AMP degraded at 120 and 250kPa O 2

15 The Effect of CO2 Loading AMP Concentration (mol/kg) 5,0 4,5 4,0 CO 2 free 0,3 mol CO2/mol AMP 3, Reaction Time (hr) 5mol/kg AMP degraded at 120 and 250kPa O 2

16 Conclusion AMP is not stable and the steric hindrance does not prevent oxazolidinone formation. The degradation of AMP is O 2 mass transfer limited under the experimental conditions. Degradation rates strongly depended on O 2 pressure. Degradation rates increased dramatically with increasing agitation rate. Transition metal ions and free radical initiator have no obvious effects on the oxidative degradation rate. Degradation rates apparently increase with CO2 loading.

17 Thank you!