Hydrogen Production via Catalytic Reformation of Landfill ...

Hydrogen Production via Catalytic Reformation of Landfill Gas and

Biogas

Nazim MURADOV, Ali T-RAISSI, FranklynSMITH, Mohamed M. ELBACCOUCH

Florida Solar Energy Center, University of Central FloridaCocoa, Florida 32922, U.S.A.

ObjectivesObjectives

• The primary objectives of this study are to:– Determine the catalytic activity of a number of

catalysts for reforming of CH4-CO2 mixtures

– Explore catalyst stability issues

– Evaluate the potential for producing hydrogen for NASA-Kennedy Space Center in Florida

CH4 + CO2 → 2H2 + 2CO ∆H298= 247 kJ/mol

Introduction (1)Introduction (1)

• Landfill gas (LFG) and biogas (BG) are important resources for production of renewable hydrogen

• LFG & BG are complex gaseous mixtures that contain CH4 and CO2 as the major constituents and small amounts of H2S & a variety of organic (e.g., alcohols, organic acids, esters) & element-organic (e.g., S-, N-,Si-containing) compounds

• Concentration of CH4 in LFG & BG vary in the range of 40-70 vol.% (the balance being mostly CO2)

Introduction (2)Introduction (2)

• Extensive sources of LFG and BG are available in the U.S.

• Presently, there are no large-scale commercial hydrogen production processes based on LFG & BG in Florida

• In Florida, 59 landfill sites generate 1.6 million m3/day LFG (in methane equivalent), that can yield about 100,000 tons of H2 gas per year

Landfill Locationswithin approximately 80 km from

NASA-KSC in Florida & their output (GJ/hr)

Landfill Locationswithin approximately 80 km from

NASA-KSC in Florida & their output (GJ/hr)

• Total capacity:0.22 million m3/day CH4

• This amount of methane will produce 50t /day H2gas

Daytona Beach, 76

Cocoa, 32

Vero Beach, 26

Winter Haven, 46

Kissimmee, 23

Orlando, 75

Sanford, 51

KSC

Nearest Landfill Site(Cocoa, Florida)

Nearest Landfill Site(Cocoa, Florida)

•• Located approx. 20 km from Located approx. 20 km from NASA/KSC in FloridaNASA/KSC in Florida

•• Capacity: Capacity: approx.approx. 30 m30 m33/min of /min of LFG (potentially, LFG (potentially, approx.approx. 60 60 mm33/min)/min)

•• Expected to produce LFG forExpected to produce LFG forabout 50 yearsabout 50 years

•• The site could potentially The site could potentially provide feedstock for production provide feedstock for production of of about 5 ton/day Habout 5 ton/day H2 2 gasgas

Composition of Cocoa LFG (vol.%):

Methane 48.3Carbon dioxide 37.1Nitrogen 11.3Oxygen 3.3Hydrogen <0.1Hydrogen sulfide <0.1Carbon monoxide <0.01Other hydrocarbons <0.01

Heating value: 490 BTU/CF

Chemical Equilibrium Considerations (1)

Chemical Equilibrium Considerations (1)

• Aspen Technology’s AspenPlusTM

chemical process simulation (CPS) platform was used to calculateequilibria of CO2-methane reacting gas

• Reforming reactions were modeled using a Gibbs reactor & by minimizing the free energies in order to determine conversions at given reaction conditions

• Input parameters were: feed composition & flow rate, inlet temperature & pressure, and reactor temperature & pressure

• Equilibrium compositions of CH4:CO2:H2O mixtures atP=1 atm were determined

CH4:CO2 = 1:1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

600 700 800 900 1000 1100 1200

Temperature (K)

Mol

e Frac

tion

CH4H2OH2CO2COC

CH4:CO2 = 1.3:1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

600 700 800 900 1000 1100 1200

Temperature (K)

Mol

e Frac

tion

CH4H2OH2CO2COC

Chemical Equilibrium Considerations (2)

Chemical Equilibrium Considerations (2)

CH4:CO2 = 1:1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

600 700 800 900 1000 1100 1200

Temperature (K)

Mol

e Frac

tion

CH4H2OH2CO2COC

CH4:CO2 = 1.3:1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

600 700 800 900 1000 1100 1200

Temperature (K)

Mol

e Frac

tion

CH4H2OH2CO2COC

• Equilibrium compositions of CH4:CO2:H2O mixtures at P=1 atm

Scenarios for ConvertingLFG to LH2

Scenarios for ConvertingLFG to LH2

∼20 km

LFG

Florida Gas Transmission Pipeline

CO2

LH2CH4

CH4 recovery plant H2 plant H2 liquefaction unit Cocoa landfill site

KSC

Scenario 1 (credit-debit, LH2 plant at NASA-KSC)Scenario 1 (credit-debit, LH2 plant at NASA-KSC)

H2

CH4-CO2 reforming plant

to KSC

to other end-users

LFG

Scenario 2 (trailer truck delivery of LH2 to NASA-KSC)Scenario 2 (trailer truck delivery of LH2 to NASA-KSC)

LH2

H2 liquefaction unit

Process Design Considerations (1)

Process Design Considerations (1)

• Option 1 - LFG reforming with preliminary recovery of CH4

Landfill Gas (CH4 – CO2)

CO2(liquid)

GSU

H2-CO

H2-CO2

H2

CO2(liquid)

H2OH2O

Steam Reformer

Shift Reactor Cryogenicseparation

Liquid CO2 sequestration

CH4

Process Design Considerations (2)

Process Design Considerations (2)

• Option 2 - Direct reformation of LFG

CO2

Landfill Gas

Reformer Shift Reactor PSA,or cryogenicseparation

H2

Sulfur and siloxane trap

H2-CO

H2-CO2

H2OH2O

CO2 sequestration

CH4 – CO2

Experimental (1)Experimental (1)

• A premixed gaseous mixture with the composition of CH4- 56.9, & CO2- 43.1 vol.% was obtained from Holox Inc. and used to mimic LFG composition in all experiments

• Ni- and Fe-based catalysts were obtained from Sud-Chemie and Alfa Aesar

Experimental (2)Experimental (2)

• Alumina-supported (0.5 and 1 wt.%) Pt, Pd &Ru catalysts were from Aldrich Chemical Co.

• Rh (5 wt.%)/Al2O3 was from Strem Chemicals

• Ir (1 wt.%)/Al2O3 was from Alfa Aesar

• A catalyst (0.5 g) was placed inside a quartz reactor (1 cm O.D.) and purged with Ar at 600oC for 1 hr before each experiment

Experimental (3)Experimental (3)

• All the experiments were conducted at the atmospheric pressure

• The flow rate of CH4-CO2 mixture into the reactor was 10 ml/min

• The reaction products were analyzed gas chromatographically

Laboratory Scale Unit for Catalytic Reforming of CH4-CO2 Mixtures

Laboratory Scale Unit for Catalytic Reforming of CH4-CO2 Mixtures

steamgenerator

reactor

catalystAr CH4-CO2

GC

syringe pump

flowmeters

T-controller

heater

pre-heater

Water collector

adsorber dryerthermocouple

vent to shift reactor

Catalytic Reformation of CH4-CO2Catalytic Reformation of CH4-CO2

0

10

20

30

40

50

60

0 100 200 300

Time (min.)

Pro

duct

s (v

ol.%

)

CO2

CH4

H2

CO

0

10

20

30

40

50

60

0 100 200 300

Time (min.)Pr

oduc

ts (v

ol.%

)

CO2CH4H2CO

• Catalytic reforming of CH4-CO2 (56.9-43.1 vol.%) mixture over Ru (0.5 wt.%)/Al2O3 (left) & NiO(15 wt.%)/Al2O3 catalysts at 850oC

Effect of SteamEffect of Steam

0

5

10

15

20

25

0 0.2 0.4 0.6 0.8 1

Steam / methane ratio (mol.)

Car

bon

(mm

ol/g

cat

.)

• To prevent carbon lay down on the NiO/Al2O3catalyst surface, steam was added. The extent of carbon lay down on the Ni-catalyst as a function of steam to methane ratio in the feed is shown in this Figure.

Comparison of CPS &Experimental ResultsComparison of CPS &Experimental Results

AspenTM Simulation Results

CH4:H2O:CO2 = 1.3:1.3:1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

600 700 800 900 1000 1100 1200

Temperature (K)M

ole

Frac

tion

CH4H2OH2CO2COC

0

10

20

30

40

50

60

70

0 60 120 180 240 300

Time (min.)

Pro

duct

s (v

ol.%

)

H2COCO2CH4

Experimental, T=850oCCH4:H2O:CO2=1.3:1.3:1NiO (15 wt.%)/Al2O3

SummarySummary

• Hydrogen production from renewable feedstocks, such as landfill gas and biogas was analytically and experimentally investigated. A wide range of catalysts were tested for reforming CH4-CO2 and CH4-CO2–H2O mixtures at 850oC & 1 atm pressure

• Experiments used a ratio of CH4/CO2 in the feedstock similar to that of the LFG from Cocoa landfill site in Florida

• Noble metal catalysts (i.e., alumina-supported Pt, Pd, Rh& Ir) show both high activity and high selectivity toward CO2 reformation of methane

Conclusions (2)Conclusions (2)• Ni catalysts were very efficient for both reforming &

methane decomposition reactions. But, CH4decomposition reaction resulted in the catalyst deactivation

• The addition of relatively small amounts of steam (steam-to-methane molar ratio of 0.5÷1) preventedNi catalyst deactivation and significantly improved its activity and stability

• The experimental data for Ni-catalyzed reforming are in good agreement with the thermodynamic equilibrium calculations for the CO2-CO4 mixtures with & without steam supplementation

AcknowledgementsAcknowledgements

Support for this work was provided by the National Aeronautics and Space

Administration (NASA) through Glenn Research Center.