design of asymmetric multilayer membranes based on mixed ionic-electronic conducting composites
Post on 19-Mar-2016
33 Views
Preview:
DESCRIPTION
TRANSCRIPT
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)
2
• 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
3
+
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
4
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
5
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)
66
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
6
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 - -
7
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)
1
8
SEM image of composite 50% LSFNi0.3+ 50% GDC sintered at 1200 0C
9
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
10
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
11
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
12
Fabrication of asymmetric multilayer membrane
porous platelet -Al2O3- Ni
coarsely dispersed particles of composite
catalyst layers
highly dispersed particles of composite
gas-tight layer
13
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
14
Reactor with catalytic membrane for partial oxidation of methane
membrane
membrane is pressurized in copper ring
titanium reactor
15
Membrane reactor performance
4.5% CH4 in He
900C
CH4 conversion and products concentration vs. reaction feed rate
16
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
17
Membrane reactor performance: POM
900C, flow rate: 5 l/h, air: 2 l/h
Effect of methane concentration on its conversion and syngas selectivity
18
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
19
• 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
20
THANK YOU FOR YOUR ATTENTION!
This work is supported by FP 7 Project NMP#-LA-2009-228953 (OCMOL)
21
22
Membrane reactor performance: POMEffect of water on methane conversion/products
concentration
4.5% CH4 in He, 900C
top related