1. Oxidative Degradation and the Oxidation-Reduction Potential of ROC20 Solutions By Fred Closmann January 10, 2008

2. Summary of Topics Covered What is Oxidation-Reduction Potential (ORP)? What is Oxidation-Reduction Potential (ORP)? Why we want to Measure ORP? Why we want to Measure ORP? How ORP Can Help US? How ORP Can Help US? Review Preliminary Data (ROC20) Review Preliminary Data (ROC20) Other Findings – High Viscosity Solvent Other Findings – High Viscosity Solvent Possible Future Experiments Possible Future Experiments

3. ORP According to ASTM method, “the ORP measurement establishes the ratio of oxidants and reductants prevailing within a solution… allows determination of the ability to oxidize or reduce species in solution.” According to ASTM method, “the ORP measurement establishes the ratio of oxidants and reductants prevailing within a solution… allows determination of the ability to oxidize or reduce species in solution.” Reacting species related by Nernst Equation. Reacting species related by Nernst Equation. Non-selective; all e-transfer reactions influence measurement. Non-selective; all e-transfer reactions influence measurement. Gross measurement - not initially concerned with exact chemistry. Gross measurement - not initially concerned with exact chemistry. Standardized method(s) (ASTM) Standardized method(s) (ASTM)

4. Standard Hydrogen Electrode We are using Ag/AgCl reference ORP Electrode

5. Flue Gas 10% CO 2 5-10% O 2 Absorber 40-70 °C 1 atm Stripper 120 °C 1 atm Cross Exchanger Where is the degradation most likely to occur? Absorber Packing Reboiler Gas w/ 1% CO 2 CO 2 H 2 O, O 2 Solvent  = 0.4 Sump

6. Why Measure ORP? Oxidative degradation can occur in the mass-transfer controlled region (Goff). Oxidative degradation can occur in the mass-transfer controlled region (Goff). Allow us to know the potential for and rate of degradation of solvents. Allow us to know the potential for and rate of degradation of solvents. Goal: Develop correlation between ORP and solvent degradation rate. Goal: Develop correlation between ORP and solvent degradation rate. Secondary Goal: Understand catalytic effect of metals on solvent oxidation. Secondary Goal: Understand catalytic effect of metals on solvent oxidation. Real-time data collection (on-line methods). Real-time data collection (on-line methods).

7. Experiments Conducted to-Date 1. Baseline: ROC20 formulations (loaded to 0.3 mole/mole based on alkalinity) aerated/stirred in glass reactor at 53.5 °C. 2. Loaded ROC20 solution augmented with 0.01 mM Cu (added as cupric sulfate). 3. Rapid shut-down of well-mixed/aerated reactor with loaded ROC20 to understand O 2 consumption (absence of copper). 4. Rapid start-up of reactor (aeration and mixing) from quiescent state (absence of copper). 5. Viscosity measurements of loaded ROC20 solutions

10. Steady-State Results Solution Characteristic ORP (mV) T (°C) Viscosity (cp)** ROC20-17953.517.8/10.5 ROC20 w/ 0.001 mM Cu -14553.5NM ROC20 w/ 0.01 mM Cu* -8053.5305/110 pH 4/7 Quinhydrone Std +246/+6423NA *ROC20 solution sat idle in reactor for 3 weeks. **Viscosity measurements made at 25/40 °C. NM – Not measured, NA – Not Applicable.

11. Interpretation of Results Negative ORP not necessarily reduced environment. Negative ORP not necessarily reduced environment. Oxygen depleted fast; 90% of ORP change occurs in 24 minutes in quiescent reactor. Oxygen depleted fast; 90% of ORP change occurs in 24 minutes in quiescent reactor. Rapid increase (<3 min) in ORP to near-steady state condition (- 185 mV) upon reactor start-up. Rapid increase (<3 min) in ORP to near-steady state condition (- 185 mV) upon reactor start-up. Copper increases ORP; consistent with previous observations related to formate production (Sexton, 2007). Copper increases ORP; consistent with previous observations related to formate production (Sexton, 2007). ROC20 became more viscous after sitting idle (305 cp vs. 18 cp at 25 °C); observation confirmed in experiment without Cu. ROC20 became more viscous after sitting idle (305 cp vs. 18 cp at 25 °C); observation confirmed in experiment without Cu.

12. Potential ORP Experiments Change reactor conditions improved mixing/aeration, and absence of both. Change reactor conditions improved mixing/aeration, and absence of both. Addition of metals species including Ferric/Ferrous Iron to ROC20 to observe iron shuttle effect on ORP. Addition of metals species including Ferric/Ferrous Iron to ROC20 to observe iron shuttle effect on ORP. Addition of cobalt and nickel to investigate catalytic effects on ORP. Addition of cobalt and nickel to investigate catalytic effects on ORP. Addition of Hydrogen Peroxide (H 2 O 2 ) to create highly oxidative environment - measure ORP and degradation of ROC20. Addition of Hydrogen Peroxide (H 2 O 2 ) to create highly oxidative environment - measure ORP and degradation of ROC20.

13. Investigate Potential ROC20 Polymerization Mechanisms 1. Recreate steps that lead to formation of highly viscous ROC20. 2. Repeat with ROC20 and other solvents. 3. Analysis using ORP, cation/anion chromatography, NMR, titration. 4. Reversible condition? Heat to 120 °C to mimic stripper operation. 5. Investigate CO 2 stripping effects of experiments. Reload back to 0.3 m/m to reverse condition – (completed). 6. Literature review – formation of urea compound or polymer based on ROC20; propose pathway to creation of polymer.