Development of Innovative Catalysts for PEM Fuel Processors by pzs15406

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									Development of Innovative Catalysts
     for PEM Fuel Processors


                            C V V Satyanarayana


           National Chemical Laboratory, Pune

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida
                    Outline of Presentation
1. Introduction to CSIR Fuel Cell Programme
2. Introduction to Fuel Processor catalysts
3. Development of Steam Reforming Catalysts &
    some results on
   (a) Ethanol and LPG Steam Reforming
   (b) Steam Reforming of iso-octane and Methane
4. Development of PROX Catalysts and Results
5. Remarks and Conclusions.
6. Future plans at NCL

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   2
             Objective of the CSIR Fuel Cell
                      programme
    Development of 5 and 25 kW PEMFC power
         packs for stationary applications
                    Funded by
         New Millennium Indian Technology Leadership
         Initiative (NMITLI) Scheme, CSIR, New Delhi
                                Project Partners
                        National Chemical Laboratory
                           Spic Science Foundation
                       Bharat Heavy Electricals Limited
                         Sud-Chemie India Limited

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   3
                                     Fuel Cell Power Pack
                                                                    Main Components
                            Oxygen    AIR
                FUEL                                                Fuel Processor : Fuel processor
             PROCESSOR
                                                 POWER              is an integrated unit used for the
                                               CONDITIONER          conversion of raw fuel to
Fuel Input
                                   FUEL
                                          DC Power       AC Power   hydrogen rich gas suitable for
                                   CELL                   Output
                       Hydrogen
                       Rich Gas
                                  STACK
                                           Output
                                                                    the fuel cell (NCL, SCIL)

                                                 Water
                                                                    Fuel Cell Stack :The hydrogen
                                                                    rich gas and oxygen (air) are fed
                                                                    to fuel cell stack to generate DC
         Fuel Processing        HEAT                                power (SPIC)
           Preheating         RECOVERY
                                                                    Power Conditioner: The DC
                                                                    power output is converted into
                                                                    useful AC power (BHEL)

  National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida    4
                        Fuel Processing




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   5
COMPONENTS OF A PEM FUEL PROCESSOR


        Desulphurizer                    Reformer               Reformate cleanup




   Fuel

            Raw fuel               Fuel conversion                    CO reduction
            cleaning                 Steam reformer                   Water gas shift reactor
                                                                       ( HTS , LTS)
                                    Partial Oxidation                     Pref.   Oxidation
                                    Autothermal reformer            (PROX)


National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   6
                Catalysts in a PEM Fuel Processor
                      Catalyst           Temp                         Reactions
                                           oC

          DS          Ni-Mo-ZnO          350      ZnO + H2S           ZnS + H2O

          SR          Ni-Ce-Zr           700      CnH2n+2+nH2O  nCO + (2n+1)H2

          HTS         Fe-Cr              380      CO + H2O  CO2+H2

          LTS         Cu-Zn-Al           200      CO + H2O            CO2+H2

          PROX        Pt-Zeolite         140      CO + 1/2O2            CO2



                            All reactors are fixed bed type

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   7
              Current steam reforming catalysts
    CH4 + H2O  CO + 3 H2; H = + 210 kJ/mol
    H2O / C = 2.5-3.0 (mol); 800-1000ºC, ~30 BAR
    GHSV = 10000 – 15000 h-1
    Ni ON REFRACTORY SUPPORTS
    SUPPORTS: CaAl2O4 FOR CH4 FEED;
    MgAl2O4 SPINEL, K2O- FOR C3+ REFORMING
    ACTIVITY DEPENDS ON Ni AREA
    EQUILIBRIUM CONVERSION AND
     SELECTIVITY
For MeOH Conventional CuO-ZnO-Al2O3 operate at
sufficiently low temperatures
National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   8
      DRAWBACKS OF CONVENTIONAL Ni -
           BASED S R CATALYSTS
       HIGH TEMPERATURES (800-1000ºC)
       SENSITIVE TO SULFUR (<0.05 PPM);
       HDS OF HEAVIES IS DIFFICULT IN A
        FUEL PROCESSOR
       SUSPECT FOR DEACTIVATION IN THE
        PRESENCE OF OLEFINS
       NOT PROVEN FOR OTHER FUELS SUCH
       AS EtOH


National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   9
               Attributes of a good SR catalyst
 Highly active to convert 100% of the hydrocarbon to its
  equilibrium composition of CO, CO2, methane and H2 at
  the reaction temperature.
 Should work at lowest possible steam/carbon ratios
  without deactivation due to filamental carbon.
 Capable of handling high space velocities to achieve
  small catalyst volumes. Durability under long steady state
  continuous operation (>5000 hrs)
 Should have high crush/mechanical strength under steam.
 Has to withstand frequent On/Off cycles.
 Tolerance to sulphur and other poisons.

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   10
  Role of a support in SR Catalysts
   To Improve mechanical strength and thermo-resistance
   To enhance and stabilise metal dispersion (eg: Ni,Pt, Rh)
   To suppress coke formation
  Features of current SR catalyst supports
   Refractory basic oxides (MgAl2O4, CaAl2O4, Al2O3
   Coke reduction by oxides of K, Mg, Mo, W, Ce, Sn
  Ceria-Zirconia supports
  The Ce3+  Ce4+ couple is more reversible in CeO2-
    ZrO2 than CeO2 indicating that Ce ions in CeO2-ZrO2 are
    more accessible. This can arise from the smaller size of
    the CeO2 crystallites in CeO2-ZrO2.

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   11
             Selection of feed stocks and Steam
                     reforming catalysts
 Naptha and natural gas are the preferred feeds for H2
 production in Industrial Steam Reforming.
Due to wide distribution network, gasoline, diesel,
 kerosine, CNG and LPG are preferred for PEMFC.
Renewable feeds such as agro-ethanol and bio-gas
 does not lead to net CO2 emissions.
Ni, Pd, Pt, Rh based catalysts are most suited for SR.
 Ni based catalysts are the best in terms of cost and
 good performance. Ni is known to catalyse the
 breaking of C-C bond.

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   12
   Preparation of Ni Steam Reforming catalysts
   » Aim is to develop catalysts that work for SR of multiple
     fuels, viz., LPG, agro-ethanol, natural gas, methanol and
     naphtha.
   » Ni supported on oxides that have red-ox properties such
     as CeO2, TiO2, CeO2-ZrO2, CeO2-ZrO2-TiO2 have been
     prepared and screened.,
   » Unique co-precipitation methodologies developed to yield
     nano-NiO particles (3-6nm) on high surface area supports.
   » Preliminary characterization is carried out by powder
     XRD and BET surface area measurements. NiO crystallite
     sizes are calculated using Scherrer equation. Temperature
     programmed reduction studies carried out to monitor
     reducibility of the NiO on these supports.
National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   13
                                                 SR of EtOH On NiO-CeO2-ZrO2 Catalyst
                                                                                0
                                        Catalyst 2.5cc, Temp. 650 C, Steam/carbon 2.5-4
                                                                                                               34
                                  100
          VOLUME PERCENT OF GAS                                                             H2O/C = 2.5        33
                                  90
                                                                                                               32




                                                                                                                    Ethanol in the feed (Wt%)
                                  80
                                                                                                               31
                                  70                                                    H2O/C = 3
                                                                                                               30
                                  60
                                                                                                               29
                                  50                                                                           28
                                  40                                                                           27
                                  30                  Ethanol Wt% in the feed
                                                                                                               26
                                                      H2 VOLUME
                                  20                  CONVERSION                                               25
                                                                                H2O/C = 4
                                  10                                                                           24

                                   0                                                                           23
                                        0   25   50   75 100 125 150 175 200 225 250 275 300 325 350 375 400
                                                                    TOS in hours




National Seminar on Fuel cell-Materials, Systems & Accessories,                           NMRL, Ambernath                                       14
                                          ON SCALE-UP CATALYST FROM SCIL
                                SR OF LPG 0                           -1
                                Temp. 700-730 C,Steam /Carbon=4.0,GHSV=21750-87000 h
                                                                                                         20
                          100
                                       CONV
                          90
                          80          H2                                                                 15




                                                                                                              Volume Percent
         Volume Percent



                          70
                                    MTS                                     HTS         87,000 h
                                                                                                    -1


                          60                                                      65,250 h
                                                                                          -1
                                                                                                         10
                          50                                         -1
                                                              43,500 h
                                                                                               CO
                          40                    -1       GHSV
                                     21,750h
                                                                                                         5
                          30         CO2

                          20

                          10                                                                             0
                                0          50           100         150           200           250
                                                     Time on Stream (Hrs)




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida                      15
                                    BUTANE & iso-BUTYLENE STEAM REFORMING
                                                          0                  -1
                                CATALYST 1.5cc, TEMP. 700 C, GHSV 14500 h , Steam/Carbon=4

                          100


                          80
         VOLUME PERCENT




                                      BUTANE REFORMING          iso-BUTYLENE REFORMING
                          60


                          40


                          20              Conversion
                                          H2 Volume

                           0
                                0    20      40    60    80   100      120        140   160   180
                                                        TOS in hours



National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida     16
                                           Steam Reforming of Iso-octane on 40%Ni/CeO2-ZrO2
                                                                     o
                                                Reaction Temp 725 C, Steam/Carbon=3.6/1


                                                                                                    8
                                  80




                                                                                                        CARBON MONOXIDE VOL%
               % Volume percent                                 GHSV=31000
                                                                                                    6
                                  60
                                                                                       Conversion
                                                                                       H2
                                                                                       CO2          4
                                                                                       CO
                                  40       GHSV=15500

                                                                                                    2

                                  20

                                                                                                    0

                                  0
                                       0    2    4   6   8   10 12 14 16 18 20 22 24 26 28 30 32

                                                             TIME ON STREAM (Hrs)




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida                                17
                                              CH4conv
                                              H2con
                                    100
                                              COconc

                                    80
              Conversion /volume%




                                    60


                                    40


                                    20


                                     0
                                           600       625       650       675      700      725
                                                           Temperature(degrees)
                                    SR of Methane on NiO-CeO2-ZrO2 catalyst at various temperatures




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida       18
      SALIENT FEATURES OF NCL REFORMING
                   CATLYSTS
Common catalyst for steam reforming of EtOH, LPG and
 Natural gas.
LPG supplied by Indian refineries has high content of
 olefins in addition to C3 and C4. Reforming of 100%
 Isobutylene was a good example to show that NCL catalyst
 can handle high concentrations of olefins in the feed
Variations in LPG composition does not have any bearing
 on performance. Catalysts show stable activity at full
 conversion even for 100% n-Butane
The Steam reforming catalysts developed at NCL show
 sulfur tolerance to low levels of sulfur. Hence, during
 steam reforming of agro-ethanol, desulfurisation of feed
 is not a pre-requisite.

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   19
     Requirements of A PROX Catalyst
  A PROX catalyst should be highly active (CO conv >99.8%)
    such that it can handle high space velocities.
  It has to operate in the temperature zone of LTS outlet
   temperature (200 oC) and PEM fuel cell stack inlet
   temperature (80 oC)
  It should have good CO oxidation selectivity in order not to
   consume valuable H2.
  Should operate at lower O2/CO ratios, preferably O2/CO  1
  No methanation of CO should occur at reaction temperatures.
  Presence of water and CO2 should not lead to any
   deterioration in the long term performance.

National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   20
    DEVELOPMENT OF PROX CATALYSTS
 Using HTS and LTS catalysts in series, the level of CO is
  brought down to 0.3 – 1.0%. The gas stream after the Shift
  reaction is further reacted with a preferential oxidation catalyst
  prepared at NCL, to bring down the CO to <10 ppm.
 Supported gold catalysts using reducible oxide supports of Fe,
  Mn, Co, Cr and Co-Mn oxide catalysts were prepared and
  evaluated in PROX reactor either in series with the steam
  reforming reactor or separately using typical gas mixtures. Mn
  and Mn-CO supports gave excellent results while other
  supported catalysts deactivated. Successful catalysts were
  tested for more than 100 hrs with various CO concentrations.
 Since Pt based catalysts have been reported to work at high
  GHSV’s with better stability, we have developed Pt based
  catalysts that work in 130-160 oC range and a zeolite based Pt
  catalyst has been scaled up to use in our processor programme.
National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   21
                                                                                                 -1
                                          PROX CATALYST: Au/ metal oxide, GHSV : 5000 h
                                                                     0
                                                TEMPERATURE: 80-90 C,

                                 24
                                 22                               CO in PPM
                                 20
          CONCENTRATION (PPM)

                                 18
                                 16
                                 14
                                 12
                                 10
                                  8
                                  6
                                  4
                                  2
                                  0
                                 -2
                                 -4                                           FEED 9600 PPM CO
                                               FEED 5100 PPM CO
                                 -6
                                 -8
                                -10
                                      0   10     20   30    40    50   60     70   80    90   100
                                                            TOS in hours




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida       22
                         OXIDATION OF CO ON Pt/Al2O3 CATALYST
                                          O
                             Temp-175 C, CO- 9500ppm, O2/CO = 1.25
                   5.0                                                              22500

                   4.5                                                              20000
                                     CO
                   4.0
                                     GHSV                                           17500
                   3.5
                                                                                    15000
       CO in ppm




                   3.0




                                                                                            GHSV
                   2.5                                                              12500

                   2.0                                                              10000
                   1.5
                                                                                    7500
                   1.0
                                                                                    5000
                   0.5

                   0.0                                                              2500
                         0   2   4   6   8 10 12 14 16 18 20 22 24 26 28 30 32 34

                                                TOS in hours



National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida    23
                                      Preferential Oxidation of CO on Pt-Zeolite
                                  Feed- H2 74.17%, CO2 23.26%, CO 4900 ppm CO/O2=1
                            100                                                                          20

                                                                                                         18

                            80                                                                           16

                                                                                                         14
                                                                                                    -1
                                                                                      20,000 h
           Vol % Hydrogen



                            60                                                   -1
                                                                                                         12
                                                                      15,000 h




                                                                                                              CO ppm
                                                                                                         10
                                      GHSV           10,000 h
                                                                -1
                                                                                           0
                            40                                                        145 C              8
                                                           0
                                                     135 C
                                      Temp
                                                                                                         6

                            20                                                                           4

                                                                                                         2

                             0                                                                           0
                                  0    2     4   6     8       10    12   14          16       18

                                                     Time on Stream




National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida                        24
                          Conclusions and Remarks
 Novel supports and co-precipitation techniques developed to
  yield good SR catalysts containing nano-particles of NiO.
 Common catalyst for SR of EtOH, LPG, CH4 and MeOH.
  100% conversions are achieved at reasonable temperatures.
  These catalysts have capability to handle high space velocities.
 Presence of olefins do not affect the performance. Variations
  in LPG composition has no bearing on the performance.
 NCL’s SR catalysts show sulfur tolerance to some extent.
  As a result, desulfurisation of the feed is not a must during the
  steam reforming of agro-ethanol.
 NCL’s PROX catalyst works in the temperature window of
  135-150 oC and at O2/CO = 1. These less severe conditions
  help in saving of valuable H2.
 Scale up and evaluation of these catalysts at Kg level has
  been successfully completed. A Fuel processor using
  complete train of these catalysts is operational at NCL.
National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida   25
                       Future plans at NCL
 Development of honeycomb based monolith ATR
  catalysts that combine SR and oxidation.
 Development of cheaper transition metal based PROX
  catalysts.
 Development of non-pyrophoric precious metal based
  steam reforming catalysts that can withstand on-off
  cycles and also have high sulphur resistance.
 Development of sulphur resistant precious and non-
  precious metal catalysts that can handle higher space
  velocities (>10,000 h-1) compared to the present water
  gas shift catalysts.
 To develop selective methanation catalysts that methanate
  CO in the presence of excess CO2.
National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

								
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