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The Role of Catalysis in Chemical Energy Storage. MTA EK, 2015.05.04. József Sándor Pap Surface Chemistry and Catalysis Department. Renewable energy sources – how to store the produced energy ?. Wind turbines – low energy density. Israel – 10 MW solar thermal pp.
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The Role of CatalysisinChemicalEnergy Storage MTA EK, 2015.05.04. József Sándor PapSurfaceChemistry and CatalysisDepartment
Renewableenergysources –howtostoretheproducedenergy? Wind turbines – low energy density Israel – 10 MW solar thermal pp. (with backup biomass facility) Renewablesareeither INTERMITTENT DIFFUSE or LOW DENSITY! Japan – 30 MW offshore solar pp.
Renewableenergysources –howtostoretheproducedenergy? "Getting battery cost down is key, but on the stationary storage side there is a lot of questions about which chemistry will dominate long term. It might not be lithium…” - Colin Langanat UBS on Tesla’s announcement of PowerwallLibatteries
Energydensitybecomesdecisivewhenitcomestoapplications • ESSENTIALS… • Appropriatevolumetric AND gravimetricenergydensity. • Ease of storage (C-based). • Less toxic, safety of precesses. • Can be usedwiththeexistingtechnologiesforfossils. • Lowenvironmentalimpact (bothproduction and use). G. Centi, et al. in Catalysis for Alternative Energy Generation, Eds. L. Guczi and A. Erdőhelyi, Springer (2012)
Hydrogen economy (an attractive way to store and distribute energy)
Analogytofossilfuels – longagostoredenergy of sunlight Hydrocarbons Hydrogen DHr° = -286 kJ/mol DHr° = -890 kJ/mol Pros: - Cheap access - Cheap storage, process and distribution - Optimal energy density - Established technologies (power plants and internal combustion engines) - Accepted by society Cons: - CO2 emission - Finite sources - efficiency limits (power plants and engines) - Air pollution 43 % percent of currentenergyusagecomesfromfossils!
Role of H2 today – production and use Consumption Production Only 0.25% of hydrogen is producedbyelectrolysis. …becauseit is profitableonlywhenelectricpowerischeap. Privilegedattentiontowaterelectrolysiscomeswiththehydrogeneconomyconcept. 109 m3N 109 m3N Steam reforming of nat. gasornaphta Synthesis of ammonia 200 190 Partialoxidation of heavyoil 120 Processheatgeneration 150 Benzine reforming 90 Processing of mineraloil 100 H YD R O G EN Coalgasification 50 Benzine reforming 25 Synthesis of ethene 33 Fisher-Tropschsynthesis 15 Chlor-alkaliindustry 10 7 Other 10 Other (oxosynth., hydrogenation, reductions) Waterelectrolysis 1,3 Encyclopedia of Electrochemistry, Vol. 5: Electrochemical Engineering, Wiley (2007)
Use of H2 (or derived products) as energy carrier • Fuel cells • Methanol fuel cells • liquid H2 carriers Surya Prakash & Oláh György (1990) The keytoefficiency and topay-off is CATALYSIS!
Production of H2 (or derived products) as energy carrier Brown-H2example: reforming- net carbon reduction of 30%. Green-H2example:electrolysisrenewable - emissions-free. Central 100,000,000 High-Temp. Water Electrolysis* Coal Gasification (carbon capture) Coal Gasification (no carbon capture) Thermo- Chemical* Water Electrolysis (solar) Biomass Gasification Ethanol Reforming 100,000 Photo- Electro- chemical Water Electrolysis (wind) 50,000 Biological Capacity (kg/day) 10,000 Distributed Natural Gas Reforming Water Electrolysis (grid) Bio-Derived Liquids Reforming 1,000 10 - 2015 2015-2020 2020-2030 Target: 0.15 € / kWh *either solar or nuclear
A considerable advantage of H2 over CHs Electrochemistry! Waterelectrolysiscan be directly connectedwithrenewablepowerplants!
What is water oxidation and why is it important? WOC: wateroxidationcatalyst, a compoundthatcanacceleratetheevolution of O2fromwater and can be attachedtoelectrodesurface.
There is plenty of space for further research, because… Homogeneouscatalysts: stability (104>TON),sensitivity (anions, contaminants) Heterogeneouscatalysts: rate (small TOF), deactivation(nano) Electrocatalysts: overpotential homogeneous: 0,6-0,9 V heterogeneous: 0,2-0,4 V Photocatalysts: smallquantumefficiencyinthevisiblerange of activation
…and studies in our laboratory
Considerations Transitionmetalsthatarecheap, abundant, have more availableoxidationstates. AIM: studying supramolecular systemsthat in part exploit molecular catalysts and carry potential to merge advantages of the differentapproaches. Three directions: (1) Ru-based catalysts and related metal-organicframeworks, (2) Cucomplexesfor electrocatalysis (3) Photosensitizedlayered double hydroxides (LDHs) for photo(electro)catalysis.
Ru-basedMOFs Problem: liganddissociationleadsto rapid deactivation Advantage: complexeswith no opensitesarethe most activecatalysts Molecularcatalysts Problem: thelack of opensitesbottleneckscatalyticapplications Advantage: porousmaterials, existingoptionsforsurfaceanchoring (SURMOF) MOFs
Photosensitized LDHs with abundant metals Layereddoublehydroxides (LDH) [M’(II)1-xM(III)x(OH)2]x+[Am-x/m•nH2O]x- - M’(II) and M(III) are variable - rM’(II) ≈ rM(III) Smallmolecule photosensitizer • - Surfaceadsorbedwater • - Weaklyboundwater • - Stroglyboundwater • - Intercalationoptions • Heatinducesreversible • changes (memoryeffect)
Thank you for attention! Köszönöm a figyelmet!