„Shift-less“ fuel processing unit to produce hydrogen from gasoline for fuel cell systems
LEM – Laboratory for Energy and Materials Cycles
ECL – Electrochemistry Laboratory
LEM – M. Bosco, T.-B. Truong, E. De Boni, F. Vogel ECL – F. Hajbolouri, G. G. Scherer
Contact: Frédéric Vogel, Paul Scherrer Institute, OVGA/104, 5232 Villigen-PSI, Switzerland - phone: +41-(0)56-310-2135 fax: +41-(0)56-310-2199 / email: frederic.vogel@psi.ch
Introduction
• One possibility to promote the commercialisation of fuel cell technology is to use H2 gained from reforming gasoline or diesel as fuel.
• PSI’s “shift-less” concept operates at lower temperatures in the reformer, producing much less CO, and is thus able to omit the shift reactors.
• To demonstrate the technical feasibility of PSI’s “shift-less”
concept, a lab-scale fuel processor was linked up to a PEFC.
Results
Experimental
¾ATR
Feed: Air, Water, and Gasoline (RON = 95, S < 1 ppm) Reactor: Fixed-bed
Catalyst: 16 g 1%Rh/CeO2/ZrO2
¾PROX
Feed: Reformate, Air Reactor: Annular fixed-bed Catalyst: 6 g 5%Ru/CeO2/ZrO2
¾On-line analytics
GC with two-column switching system, TCD and FID detectors
¾Fuel cell
30 cm2PEFC with meander flow field graphite plates
Electrolyte membrane (Nafion® 112) coating: PtRu (anode), Pt (cathode) Lab-scale gasoline fuel processor
Schematic of the gasoline reformer-fuel cell system linkup at PSI
ATR conditions Reformer
outlet temperature
610°C
S/C 2.86
O/C 0.57
WHSV 0.5
ggasoline/(gcat.h) GHSV 4’738 h-1
PROX conditions Inlet
temperature 140°C O2/CO 1.24 GHSV 12’634 h-1 700 -
900°C
550 - 650°C
250 -
450°C 150°C 60°C
150°C 60°C
Autothermal Reforming (ATR)
Shift
CO + H2O →CO2+ H2
Preferential Oxidation
(PROX)
PE Fuel Cell
HC Feed
Water Air
HC Feed (low sulfur)
2-5% CO Water
Air
Conventional Process
PSI “shift-less” concept Water
< 50 ppm CO
< 50 ppm CO 10-20% CO
Air
Air Air
Air
Results
550 -
650°C 150°C
Autothermal Reforming
Preferential Oxidation Water
Air
Air O2/Air
HC Reformate
Humidification
O2/Air 2-5 % CO
550 -
650°C 150°C
Air
Reformate 2-5 % CO
Conclusions
• Reforming gasoline at lower temperatures (550-650°C) using a proprietary noble metal catalyst resulted in lower CO concentrations (2 - 5%) than conventional reformers.
• The CO content in the hydrogen-rich reformate could be reduced to < 36 ppmv in one annular fixed-bed PROX reactor.
• Operating the fuel cell with a reformate gas containing 32% of H2and < 36 ppmv of CO resulted in a cell voltage of 700 mV (with oxygen) at a current density of 500 mA/cm2, which was only 40 mV less than with pure H2.
10:0011:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 0.0
0.1 0.2 0.3 0.4 0.5 10 15 20 25 30 35 40 45 50
ATR: T=625°C; P=4 bara; WHSV(GHSV)=0.50(4738) [1/h]; S/C=2.86; O/C=0.57 Prox: T=140°C; P=4 bara; O2=46 ml/Min.; GHSV=12634 [1/h]
Link up to FC
Concentration [Vol.%]
Time CO2 H2 N2 CH4 CO
O2 PROX Off
Fuel Cell
Results (after PROX, dry)
H2 32 Vol. % N2
CO CH4 13 Vol. %
Carbon conversion
(C2+)
100 % H2yield
7.5 mol H2/mol C7.3H12.6 Reformate
(dry) 47 L/h CO
Conversion > 99.93 % CO2 29 Vol. %
27 Vol. %
H2loss 27 %
< 36 ppmv
1 bara Panode,cathode
1.5 / 2 λfuel/ λair
T hum, cathode and 35°C
anode
60°C Tcell
Fuel cell conditions Fuel cell polarization curves for
reformate gas as fuel
Best operating conditions for minimizing CO concentration in the reformate gas (p = 4 bar)
Humidification
