Hydrogen Production from Lignite and Subbituminous Coals

1. Hydrogen Production from Lignite and Subbituminous Coals Panel 3: Coal to Hydrogen 4th Annual Hydrogen Implementation Conference Laramie, Wyoming Steve Benson July 22–24, 2008

2. National Center for Hydrogen Technology (NCHT) 2

3. Selected Gasification Activities at the EERC

4. Overview • Gasification of coal • Lignite and subbituminous coals • Key challenges • Bench- and pilot-scale testing • Future opportunities 4

5. Conventional Gasification Air Coal O Air Separation 2 Gasification Steam Unit Quench Cooler and Scrubber Water–Gas Shift Steam (sour high temperature) Acid Gas Claus Plant S Sulfur Removal Tail Gas CO Capture CO 2 2 (physical scrubbbng) Power Pressure Swing Tail Adsorption Generation Gas Hydrogen Electricity 5

6. “Advanced” Gasification System Coal Air O Air Separation 2 Gasification Steam Unit Hot-Gas Cleanup And Sulfur Removal Mercury Capture High-Temperature Shift Membrane Separation Hydrogen CO2-Rich Gas O2 O Combustor 2 Turbine Power Electricity Expander Generation CO2 H2O 6

7. Key Challenges Air Coal O Air Separation 2 Gasification Steam Unit Hot-Gas Cleanup and Sulfur Removal Mercury Capture High-Temperature Shift Membrane Separation Hydrogen CO2-Rich Gas O2 O Combustor 2 Turbine Power Electricity Expander Generation CO2 H2O 7

8. What Is the Best Conversion Technology? Key Fuel Properties • Moisture content • Coal reactivity • Caking properties • Inorganic materials – Ash/slag and trace elements • Sulfur levels • Oxygen content 8

9. Lignite and Subbituminous – High Reactivity Reactivity • Organic structure • Inorganic components Included Minerals Steam O2 Na+ Ca++ Mg++ Excluded Minerals Catalytic Activity Na, Ca, Mg

10. Predicted using equilibrium thermodynamics Assumes equilibrium distribution of phases Distribution of Inorganic Phases Low- and High-Temp. Gasifiers 10

11. Bench- and Pilot-Scale Testing – Lignite and Subbituminous Coals • Bench-scale testing – fluidized bed – 4 lb/hr • Range of lignite and subbituminous coals • Test hot-gas cleanup for particulate, S, alkali, Cl, Hg • Test shift catalysts • Test membrane separation • Pilot-scale testing – transport reactor – 250 lb/hr • Lignite from Texas • Test hot-gas cleanup for particulate, S, alkali, Cl, Hg • Test shift catalysts • Test hydrogen membrane separation 11

12. Water–Gas Shift (WGS) and Hydrogen Separation • High- and low-temperature WGS catalyst to maximize hydrogen yields. • Hydrogen separation membrane for warm-gas purification of hydrogen. Transport Sulfur Removal Hot-Gas Filter Vessel CFB Reactor Coal Feed Mercury Control HT WGS Sulfur Polishing LT WGS H2/CO2 Separation 12

13. Sulfur Removal ResultsPolishing Bed • Achieved as low as 0.01 ppm H2S. 99% 99.9% % Removal 99.99% 99.999% Freedom 13

14. Mercury ResultsMetal-Based Sorbent • Red Hills Lignite • 410°F • ~95% Removal 14

15. Hydrogen Separation at Elevated Temperature • Slipstream pulled from TRDU for warm-gas cleanup and hydrogen separation • All cleanup and separation operations performed above 400°F Transport Reactor for Sulfur Removal TRDU Hot-Gas Filter Vessel Mercury/Trace Element Control Chlorine Guard/LT WGS H2 Separation Membrane HT WGS Sulfur Polishing Raffinate Pure Hydrogen TRDU Slipstream ~300 scfh 15

16. Transport TRDU Hot-Gas Reactor for Filter Vessel Sulfur Mercury/ Removal Trace Chlorine H2 Element Guard/LT HT Sulfur Separation Control WGS WGS Polishing Membrane Raffinate Pure Hydrogen TRDU Slipstream ~300 scfh Gas Analysis Results High-Temp. WGS Outlet Low-Temp. WGS Outlet Sulfur Reactor Inlet Sulfur Reactor Outlet Unit Unit Unit Unit Component Component Component Component Concentration Concentration Concentration Concentration H2 7.7 % H2 10.9 % H2 13.3 % H2 8.3 % CO 4.4 % CO 1.0 % CO 0.1 % CO 4.8 % CO2 13.8 % CO2 16.7 % CO2 18.4 % CO2 15.0 % N2 72.3 % N2 68.6 % N2 65.5 % N2 69.1 % CH4 1.5 % CH4 1.5 % CH4 1.6 % CH4 1.7 % H2S 4.4 ppm H2S 3.0 ppm H2S 0 ppm H2S 3455 ppm H2/CO 1.8 ratio H2/CO 11.0 ratio H2/CO 98.3 ratio H2/CO 1.7 ratio

17. Date: 6/10/2008 Date: 6/11/2008 Date: 6/13/2008 Measured Normalized Measured Normalized Measured Normalized Hydrogen 96.48 96.86 97.48 97.67 96.74 96.76 Carbon Dioxide 0.69 0.69 0.54 0.54 0.07 0.07 Oxygen/Argon 2.44 2.45 1.79 1.79 0.43 0.43 Nitrogen 2.74 2.74 Total 99.61 100.00 99.81 100.00 99.98 100.00 Real Btu (saturated) 309.52 312.10 309.20 Real Btu (dry) 315.00 317.63 314.68 Ideal Specfic Gravity 0.10 0.09 0.10 Real Specific Gravity 0.10 0.09 0.10 Ave. Molecular Weight 2.86 2.64 2.89 Hydrogen Stream Characteristics mol% • After nearly 50 hours of operation, CO2 concentration in the permeate was nearly zero. • Oxygen and nitrogen were present because of a leak in the sample system (a vacuum pump was used). • About >99.9% purity of hydrogen is anticipated without a leak in the sample system. 17

18. Coal-to-Hydrogen Demonstration • Demonstrated the technical capability to produce a pure stream of hydrogen from lignite coal while maintaining gas temperature above 400°F. • Demonstration was completed using commercial or near-commercial technologies. • Texas lignite was gasified in the EERC’s transport reactor development unit (TRDU), and a slipstream was cleaned and purified. 18

19. Future Testing • The hydrogen flux was very low because the TRDU runs at 120 psig. • The highest driving force for hydrogen through the membrane was only 3.4 psi. • Additional testing will take place on higher-pressure systems, including a 300-psi bench-scale entrained-flow gasifier. • This will eliminate the need for a vacuum pump to pull hydrogen product gas and should result in pure hydrogen samples. 19

20. Contact Information Energy & Environmental Research Center University of North Dakota 15 North 23rd Street, Stop 9018 Grand Forks, North Dakota 58202-9018 World Wide Web: www.undeerc.org Telephone No. (701) 777-5000 Fax No. (701) 777-5181 Steven A. Benson, Ph.D. Senior Research Manager (701) 777-5177 sbenson@undeerc.org 20