CO2 absorption by biphasic solvents: aqueous mixtures of MEA + BmimBF4

Transcription

1 Emission Control and New Energy CO2 absorption by biphasic solvents: aqueous mixtures of MEA + BmimBF4 Xu Lingjun 1, Qi Yang 2, Wang Shujuan 1 (1. Department of Thermal Engineering, Tsinghua University 2. CSIRO Manufacturing)

2 Contents Introduction Bubble Experiment and analysis Quantitative Absorption Experiment Conclusions & Future Work 1

3 History of absorbents for CO2 1930s Today 1st generation 2nd generation 3rd generation Alkanolamine: MEA, DEA Mixed amines: MEA+MDEA, MEA+PZ Two-phase absorbents Tertiary amine: MDEA Polyamines:PZ,AEEA Ionic liquids Sterical hindered amines: AMP Nanofluids Ammonia, amino acid salt.. Non-aqueous solution 2

4 Ionic Liquids as CO2 Absorbents Advantages Nonvolatile Stable Properties Tunable chemistry Disadvantages High Viscosity Loading (high pressure) Expensive (TSIL) Mixture of amines and ILs New kinds of ILs 3

5 Contents Introduction Bubble Experiment and analysis Quantitative Absorption Experiment Conclusions & Future Work 4

6 Bubble Experiment Absorption temperature 40 Pressure Atmospheric pressure Gas flow rate of CO2 Gas flow rate of N2 6mL/min 44mL/min Experiments information Structures of MEA (left) and BmimBF4(right) Experiment system 5

7 Bubble Experiment Q out CO2 out = Q N2 out 1 C Q N2 CO2 Q CO2 is the flow rate of CO2 after the reactions (mol/s), Q N2 is the flow rate of N2 (mol/s), C out CO2 is the mole fraction of CO2 after the reactions r abs = Q in CO2 out Q CO2 V r abs is the rate of absorption (mol/(s L)), V is the volume of absorbent (L). R abs (t) = න 0 R abs t is the Absorption capacity at a certain time. t r abs dt 6

8 Promoting effect on absorption 1.0E E E-04 absorption rate r (mol/(l s)) 7.0E E E E E E E-04 30wt.% MEA 30wt.% MEA+5wt.% BmimBF4 30wt.% MEA+10wt.% BmimBF4 30wt.% MEA+20wt.% BmimBF4 30wt.% MEA+40wt.% BmimBF4 30wt.% MEA+60wt.% BmimBF4 0.0E loading of CO 2 α (mol CO2/mol amine) Curves of absorption rate with CO2 loading Suitable concentration of ionic liquids Viscosity 7

9 Liquid-liquid two-phase a Delamination interface b The phenomenon of liquid-liquid stratification Quantitative C13 NMR spectrum of the upper (a) and lower (b) liquid phases of the aqueous mixtures of 30wt.%MEA +40wt.% BmimBF4 when the loading of CO2 is wt.% MEA 30wt.% MEA+5wt.% BmimBF4 30wt.% MEA+10wt.% BmimBF4 30wt.% MEA+20wt.% BmimBF4 30wt.% MEA+40wt.% BmimBF4 30wt.% MEA+60wt.% BmimBF4 Loading of stratification begins to appear No stratification No stratification No stratification Because of the formation of carbamate, the dissolution equilibrium was broken and CO2 was mainly distributed in the organic amine phase. 8

10 Contents Introduction Bubble Experiment and analysis Quantitative Absorption Experiment Conclusions & Future Work 9

11 Experiments information PC Gas pump IR CO2 Analyzer P T P T Solenoid valve Heater Tank 1 Tank 2 Pump N2 CO2 Experiment system Determined gas-liquid contact area Flux of whole process (fresh to rich) Relatively Stable gas environment:12% CO2, 88% N2 10

12 Experiments information PC Gas pump IR CO2 Analyzer P T P T Solenoid valve Heater Tank 1 Tank 2 Pump N2 CO2 Experiment system 11

13 Experiments information PC Gas pump IR CO2 Analyzer P T P T Solenoid valve Heater Tank 1 Tank 2 Reacter Pump N2 CO2 Experiment system Tank 1: Calculate the consumption of CO2 Tank 2: Expand the volume of reactor 12

14 Experiments information PC Gas pump IR CO2 Analyzer P T P T Solenoid valve Heater Tank 1 Tank 2 Pump N2 CO2 Experiment system Determined gas-liquid contact area Relatively Stable gas environment:12% CO2, 88% N2 13

15 To get relatively Stable gas environment Percentage of CO2 concentration/ % Solenoid valve controlled by numerical value of pressure in reactor IR CO2 Analyzer real time monitoring reaction time/ s An example of variation of CO2 concentration with time 14

16 To get quantitative reaction flux Consumption of CO2 (with time) Calculate from CO2 pressure in gas tank, using Peng-Robins gas equation Quantitative reaction flux of CO2 Flux = Q t 1 S Q is the consumption of CO2 (mol), t is the reaction time (s), S is the contact area of gas and liquid(m 2 ) absorption rate r (mol/(s m^2)) 1.2E E-10 30wt.% MEA 8.0E E E E E react time (s) 15

17 Contents Introduction Bubble Experiment and analysis Quantitative Absorption Experiment Conclusions & Future Work 16

18 Conclusions Promoting effect of ionic liquids on absorption Appropriate concentration The phenomenon of liquid-liquid stratification Caused by the formation of carbamate Quantitative Absorption Experiment Which can get determined gas-liquid contact area and relatively stable gas environment Quantitatively calculate reaction flux in the whole experimental process 17

19 Future Work Promoting mechanism Dynamic verification Improvement of test method 18

20 Thank you for listening! Contact information: Emission Control and New Energy