1. Utilization of Landfill Gas towards High-BTU Methane and Low-Cost Hydrogen Fuel by Manolis M. Tomadakis and Howell H. Heck Florida Institute of Technology Melbourne, FL 32901

2. Outline ã Rationale ã Objectives ã Methodology ã Preliminary Results ã Anticipated Benefits

3. Rationale ã H 2 S is among the components of landfill gas, which contains primarily CO 2 and CH 4 ã Photolytic decomposition of H 2 S provides an alternative source of hydrogen fuel ã Removal of H 2 S from landfill gas would help prevent odors, hazards and corrosion ã Removal of CO 2 would increase the BTU value of the remaining methane gas

4. Objectives 1. Test the efficiency of molecular sieves 4A, 5A, 13X in separating landfill gas towards high-BTU methane and FSEC- quality H 2 S (>50% H 2 S and <1% CO 2 ) by Pressure Swing Adsorption (PSA) 2. Investigate the effect of the landfill gas H 2 S content on the PSA process efficiency, by varying the H 2 S feed volume fraction in the range 0-1 %

5. Objectives (cont’d) 3. Determine the effect of pressure on CH 4 and H 2 S product recovery and purity, by varying the system high pressure in the range 40-100 psig. 4. Examine the effect of near-equilibrium operation of the PSA process on the percent utilized sieve capacity and overall process efficiency, by varying the gas feed flowrate.

6. Pressure Swing Adsorption System Layout

7. Pressure Swing Adsorption Apparatus

8. Experimental Methodology Column I 1.Pressurization to the desired adsorption pressure by pure CH 4 2. Adsorption - supplying a mixture of CH 4, CO 2 and H 2 S 3. Blowdown to the initial pressure (~1 atm) 4. Desorption - purging with inert N 2 at nearly atmospheric pressure

9. Experimental Methodology Column II 1. Pressurization to the selected adsorption pressure by the adsorption product of column I or a directly supplied mixture of CO 2 /H 2 S 2. Adsorption at the desired high pressure 3. Blowdown to the initial pressure 4. Desorption by purging with inert N 2 at nearly atmospheric pressure

10. Preliminary Testing 1. Molecular Sieves 13X and 4A were packed in Columns I and II, respectively 2. A mixture of CH 4 -CO 2 -H 2 S was supplied to Bed I to separate CH 4 3. A mixture of CO 2 -H 2 S was supplied to Bed II to separate CO 2 and recover H 2 S 4. Adsorption and desorption in Beds I & II were carried out at 100 psig & 0 psig, respectively

11. Preliminary Experiments

12. Ratio of Outlet to Inlet Molar Flow during Adsorption

13. Ratio of Inlet to Outlet Molar Flow during Desorption

14. Gas Product Composition in Bed I during Adsorption

15. Gas Product Composition in Bed I during Desorption

16. Gas Product Composition in Bed II during Adsorption

17. Gas Product Composition in Bed II during Desorption

18. H 2 S/CO 2 Molar Ratio in Bed II Desorption Product

19. Sieve Capacity & Utilization 1. Column I adsorption loads: 0.9 kg CH 4, 2.4 kg CO 2, & 2 kg H 2 S/100 kg 13X Column I sieve equilibrium capacities: 23 kg CO 2 or 19 kg H 2 S per 100 kg 13X 2. Column II adsorption loads: 2.8 kg CO 2 and 1.9 kg H 2 S per 100 kg 4A Column II sieve equilibrium capacities: 18 kg CO 2 or 14 kg H 2 S per 100 kg 4A

20. Summary of Preliminary Results 1. A 50% CH 4 feed over 13X ZMS resulted to 98%-99% product CH 4 during adsorption 2. A 68% CO 2 - 32 % H 2 S feed over 4A ZMS resulted to 71% H 2 S and 29% CO 2 product during desorption 3.A 20-30% utilization of equilibrium sieve capacity was encountered

21. Expected Technical Results of Proposed Study Variation of the PSA product purity and recovery (CH 4 %, H 2 S%, CO 2 %) and utilized % sieve capacity with: a) Type of utilized molecular sieve (4A, 5A, 13X) b) H 2 S content of landfill gas (0-1%) c) Maximum applied pressure (40-100 psig) d) Landfill gas feed flowrate

22. Anticipated Benefits Development of environmentally acceptable & financially sound end use for landfill gas, providing both a high-BTU CH 4 stream and a low-cost H 2 S feed stream supply for the FSEC renewable hydrogen fuel program