Development of Innovative Catalysts for PEM Fuel Processors

1. Development of Innovative Catalysts for PEM Fuel Processors National Chemical Laboratory, Pune C V V Satyanarayana National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

2. Outline of Presentation 1. Introduction to CSIR Fuel Cell Programme 2. Introduction to Fuel Processor catalysts • 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 2 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

3. 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 3 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

4. POWER CONDITIONER Fuel Cell Power Pack Main Components Fuel Processor : Fuel processor is an integrated unit used for the conversion of raw fuel to hydrogen rich gas suitable for the fuel cell (NCL, SCIL) Fuel Cell Stack :The hydrogen rich gas and oxygen (air) are fed to fuel cell stack to generate DC power(SPIC) Power Conditioner: The DC power output is converted into useful AC power (BHEL) Oxygen AIR FUEL PROCESSOR FUELCELLSTACK AC Power Output DC Power Output Fuel Input Hydrogen Rich Gas Water Fuel Processing Preheating HEATRECOVERY 4 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

5. Fuel Processing 5 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

6. COMPONENTS OF A PEM FUEL PROCESSOR Desulphurizer Reformer Reformate cleanup Fuel Raw fuel cleaning Fuel conversion COreduction Steamreformer Water gas shift reactor ( HTS , LTS) Pref. Oxidation (PROX) Partial Oxidation Autothermal reformer 6 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

7. Catalysts in a PEM Fuel Processor All reactors are fixed bed type 7 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

8. 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 8 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

9. 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 9 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

10. 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. 10 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

11. 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. 11 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

12. 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. 12 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

13. 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. 13 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

14. 14 National Seminar on Fuel cell-Materials, Systems & Accessories, NMRL, Ambernath

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19. 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. 19 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

20. 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. 20 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

21. 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. 21 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

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25. 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. 25 National Seminar on “Creating Infrastructure for Adoption of Fuel cell Technology”, NTPC, Noida

26. 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

27. Thanks For your Attention NTPC R&D for Invitation