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Design of asymmetric multilayer membranes based on mixed ionicelectronic conducting composites (OCMOL Project) V. Sadykov1,2, Vladimir V. Usoltsev1, V. Zarubina1, S. Pavlova1, N. Mezentseva1, T. Krieger1, G. Alikina1, A. Ishchenko1, V. Rogov1, V. Muzykantov1, V. Belyaev1, O. Smorygo4, N. Uvarov5 1Boreskov 2 Institute of Catalysis, Novosibirsk, Russia Novosibirsk State University, Novosibirsk, Russia 4Powder 5Institute Metallurgy Institute, Minsk, Belarus of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia Applications Membranes based on mixed oxide-ion and electronic conductors • separation of O2 • catalytic partial oxidation of light hydrocarbons Natural gas CH4+1/2O2 O-2 CO+2H2 2 Air e- H2+CO catalyst membrane 2 Problems and solution ways Membranes based on mixed oxide-ion and electronic conductors Single phase materials • unstable in reducing atmosphere • low oxygen diffusivity • high coefficient of thermal expansion • low thermal stability Membrane structure: Dense membranes • large thickness • low oxygen flux Composite materials • high mixed conductivity • activation of oxygen • chemical stablity • сompatibility with other materials + Asymmetric membranes • thin gas-tight layer • oxygen activation over porous layer • higher oxygen flux 3 Aim of work To design asymmetric multilayer membranes based on mixed ionic-electronic conducting composites Tasks: • synthesis of MIEC composites comprised of Ce0.9Gd0.1O2- (GDC) and La0.8Sr0.2Fe1-xNixO3- (x = 0.1 - 0.4) (LSFNx) • study of composite structure and transport properties • elaboration of procedures to support the multilayer asymmetric membrane on the macroporous metallic plate made from Ni-Al alloy compressed foam 4 Synthesis Polymerized precursor route (Pechini) Ce0.9Gd0.1O2- (GDC) La0.8Sr0.2Fe1-xNixO3- (LSFNx) fluorite perovskite Ultrasonic dispergation of powders with isopropanole + butyral resin Drying and calcinations at 700 – 1200oC LSFNx+GDC composites 5 Intensity, a. u. Structural features of composites: XRD data on interaction of perovskite and fluorite phases GDC Change in lattice parameters of perovskite and fluorite involved in composite implies their interaction due to some interface redistribution of elements composite LSFNi0.3 22,6 22,8 23,0 28,2 2 28,5 1200oC 28,8 Lattice parameter perovskite fluorite individual composite individual composite a 5.519 5.491 5.418 5.445 b 5.519 5.535 - - c 13.364 7.802 - - 6 6 TEM image of perovskite particle with fluorite phase domain in composite (50% LSFNi0.4+ 50% GDC) sintered at 700 0C d = 3.21Å (111) fluorite 1 perovskite 7 SEM image of composite 50% LSFNi0.3+ 50% GDC sintered at 1200 0C 8 Transport properties of composites: Oxygen Isotope Exchange LSFNi0.4+GDC • oxygen mobility increases with adding a second phase • increase of sintering temperature leads to the rise of oxygen mobility 9 Transport properties of composites: temperature-programmed desorption of oxygen LSFNix + GDC X = 0.1 - 0.4 Amount of desorbed oxygen Ni0.4 14 q, monolayers 12 10 Ni0.3 8 6 4 Ni0.2 Ni0.1 2 0 10 Transport properties of composites: evaluation of oxygen chemical diffusion coefficient by thermogravimetric method Sample 2 -1 lg (D/cm s ) -5,0 Kcal/mol LSFN0.3+GDC -5,2 -5,4 LSFN0.4+GDC LSFNi0.3 -5,6 0,80 0,85 0,90 0,95 -1 1000/T, K Еа , LSFNi0.3 30 LSFNi0.3+GDC 23 LSFNi0.4+GDC 20 1,00 Oxygen diffusion is governed by Ni content in perovskite Pellets were sintered at 1300 0C 11 Fabrication of asymmetric multilayer membrane catalyst layers gas-tight layer highly dispersed particles of composite porous platelet -Al2O3- Ni coarsely dispersed particles of composite 12 Preparation of membrane initial platelet -Al2O3-Ni coarsely dispersed composite La0.8Sr0.2Fe0.6Ni0.3O3 + Ce0.9Gd0.1O1.95 highly dispersed composite La0.8Sr0.2Fe0.6Ni0.3O3 + Ce0.9Gd0.1O1.95 from slurry gas-tight layer Ce0.9Gd0.1O1.95 + MnFe2O4 catalyst Pr0.3Ce0.35Zr0.35Ox catalyst LaNiPt impregnation 13 Reactor with catalytic membrane for partial oxidation of methane membrane titanium reactor membrane is pressurized in copper ring 14 Membrane reactor performance CH4 conversion and products concentration vs. reaction feed rate 4.5% CH4 in He 900C 15 Membrane reactor performance: POM Effect of methane concentration in reaction mixture on its conversion and syngas selectivity 900C, flow rate: 5 l/h, air: 1.2 l/h 16 Membrane reactor performance: POM Effect of methane concentration on its conversion and syngas selectivity 900C, flow rate: 5 l/h, air: 2 l/h 17 Membrane reactor performance: POM Effect of temperature on exit concentrations in highly concentrated mixtures flow rate: 5 l/h, air: 3.2 l/h Testing for more than 100 h at 950–980 ◦C with feed containing about 20% CH4 demonstrated a stable performance without degradation or coking 18 Conclusion • LSFN-GDC nanocomposites prepared via ultrasonic dispersion of powders in organic solvents with addition of surfactants demonstrate a high oxygen permeability due to positive role of perovskite-fluorite interfaces as paths for fast oxygen migration • Procedures for design of asymmetric oxygen-conducting membranes comprised of MIEC layers with graded porosity and composition (LSNF-GDC, MF-GDC) supported on compressed foam Ni-Al planar substrate were elaborated and optimized • Testing of asymmetric multilayer membranes in POM demonstrated good and stable performance promising for the practical application 19 THANK YOU FOR YOUR ATTENTION! This work is supported by FP 7 Project NMP#-LA-2009-228953 (OCMOL) 20 21 Membrane reactor performance: POM Effect of water on methane conversion/products concentration 4.5% CH4 in He, 900C 22