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 Institute of Catalysis, Novosibirsk, Russia2 Novosibirsk State University, Novosibirsk, Russia

4Powder Metallurgy Institute, Minsk, Belarus5Institute of Solid State Chemistry and Mechanochemistry,

Novosibirsk, Russia

Design of asymmetric multilayer Design of asymmetric multilayer membranes based on mixed ionic-membranes based on mixed ionic-electronic conducting compositeselectronic conducting composites

(OCMOL Project)(OCMOL Project)

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• separation of O2

• catalytic partial oxidation of light hydrocarbons

CH4+1/2O2 CO+2H2Natural gas

O-2 2 e-

H2+CO

Air

membranecatalyst

Applications

Membranes based on mixed oxide-ion and electronic conductors

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+

Problems and solution ways

Membrane structure: Dense membranes

Asymmetric membranes

Single phase materials Composite materials

Membranes based on mixed oxide-ion and electronic conductors

• unstable in reducing atmosphere• low oxygen diffusivity• high coefficient of thermal expansion• low thermal stability

• high mixed conductivity• activation of oxygen • chemical stablity• сompatibility with other materials

• large thickness• low oxygen flux

• thin gas-tight layer• oxygen activation over porous layer• higher oxygen flux

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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

Aim of work

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Synthesis

Ce0.9Gd0.1O2- (GDC)

fluorite

La0.8Sr0.2Fe1-xNixO3- (LSFNx)

perovskite

Ultrasonic dispergation of powders

with isopropanole + butyral resin

Drying and calcinations at 700 – 1200oC

LSFNx+GDC

composites

Polymerized precursor route (Pechini)

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Structural features of composites: XRD data on interaction of perovskite and fluorite phases

Change in lattice parameters of perovskite and fluorite involved in composite implies their interaction due to some interface redistribution of elements

1200oC

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22,6 22,8 23,0 28,2 28,5 28,8

Inte

nsity

, a. u

.

2

LSFNi0.3

GDC

composite

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 - -

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fluorite

perovskite

TEM image of perovskite particle with fluorite phase domain in composite (50% LSFNi0.4+ 50% GDC) sintered at 700 0C

d = 3.21Å(111)

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SEM image of composite 50% LSFNi0.3+ 50% GDC sintered at 1200 0C

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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

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Amount of desorbed oxygen

Transport properties of composites: temperature-programmed desorption of oxygen

Ni0.4

Ni0.3

Ni0.2Ni0.1

0

2

4

6

8

10

12

14

q, m

onol

ayer

s

LSFNix + GDCX = 0.1 - 0.4

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Transport properties of composites: evaluation of oxygen chemical diffusion coefficient by thermogravimetric method

Sample Еа, Kcal/mol

LSFNi0.3 30

LSFNi0.3+GDC 23

LSFNi0.4+GDC 20

Oxygen diffusion is governed by Ni content in perovskite

Pellets were sintered at 1300 0C

0,80 0,85 0,90 0,95 1,00

-5,6

-5,4

-5,2

-5,0

LSFNi0.3

LSFN0.4+GDC

LSFN0.3+GDC

lg (D

/cm

2 s-1)

1000/T, K-1

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Fabrication of asymmetric multilayer membrane

porous platelet -Al2O3- Ni

coarsely dispersed particles of composite

catalyst layers

highly dispersed particles of composite

gas-tight layer

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Preparation of membrane

impregnation

initial platelet -Al2O3-Ni

coarsely dispersed compositeLa0.8Sr0.2Fe0.6Ni0.3O3 + Ce0.9Gd0.1O1.95

highly dispersed compositeLa0.8Sr0.2Fe0.6Ni0.3O3 + Ce0.9Gd0.1O1.95

gas-tight layerCe0.9Gd0.1O1.95 + MnFe2O4

catalystPr0.3Ce0.35Zr0.35Ox

catalyst LaNiPt

from

slurry

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Reactor with catalytic membrane for partial oxidation of methane

membrane

membrane is pressurized in copper ring

titanium reactor

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Membrane reactor performance

4.5% CH4 in He

900C

CH4 conversion and products concentration vs. reaction feed rate

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Membrane reactor performance: POM

900C, flow rate: 5 l/h, air: 1.2 l/h

Effect of methane concentration in reaction mixture on its conversion and syngas selectivity

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Membrane reactor performance: POM

900C, flow rate: 5 l/h, air: 2 l/h

Effect of methane concentration on its conversion and syngas selectivity

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Membrane reactor performance: POM

flow rate: 5 l/h, air: 3.2 l/h

Effect of temperature on exit concentrations in highly concentrated mixtures

Testing for more than 100 h at 950–980 ◦C with feed containing about 20% CH4 demonstrated a stable

performance without degradation or coking

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• LSFN-GDC nanocomposites prepared via ultrasonic dispersion LSFN-GDC nanocomposites prepared via ultrasonic dispersion of powders in organic solvents with addition of surfactants of powders in organic solvents with addition of surfactants demonstrate a high oxygen permeability due to positive role of demonstrate a high oxygen permeability due to positive role of perovskite-fluorite interfaces as paths for fast oxygen migration perovskite-fluorite interfaces as paths for fast oxygen migration

• Procedures for design of asymmetric oxygen-conducting Procedures for design of asymmetric oxygen-conducting membranes comprised of MIEC layers with graded porosity and membranes comprised of MIEC layers with graded porosity and composition (LSNF-GDC, MF-GDC) supported on compressed composition (LSNF-GDC, MF-GDC) supported on compressed foam Ni-Al planar substrate were elaborated and optimized foam Ni-Al planar substrate were elaborated and optimized

• Testing of asymmetric multilayer membranes in POM Testing of asymmetric multilayer membranes in POM demonstrated good and stable performance promising for the demonstrated good and stable performance promising for the practical application practical application

Conclusion

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THANK YOU FOR YOUR ATTENTION!

This work is supported by FP 7 Project NMP#-LA-2009-228953 (OCMOL)

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Membrane reactor performance: POMEffect of water on methane conversion/products

concentration

4.5% CH4 in He, 900C