Membranes preparation

Dr. Marie-Laure Fontaine SINTEF

CARENA processes and membranes

H2 selective membranes: - Pd based membranes - Dense ceramic membranes

O2 selective membranes: - Dense ceramic membranes

H2O selective membranes: - Polymer based membranes - Hybrid membranes - Microporous membranes

Content

• Pd based membranes

• Dense ceramic membranes

– Oxygen selective membranes

– Hydrogen selective membranes

Pd-alloy membranes

Pf

Pd-alloy

H N N

N N

N

N N

H

H H

H H H H

H

H H H H

H

H H

N N

Pp

thickness dP

EU-7FP CACHET-II project (Contract no.: 241342)

EU-7FP CARENA (Contract no.: 263007)

RCN-Renergi and CLIMIT (Project No: 190779/S60)

Pd based membranes

Activities in CARENA beyond SOA:

• Understanding degradation mechanisms

• Manufacturing technology for scaling up production of Pd membranes

• Testing of "real performance"

• Coking resistance

HIGH FLUX; LARGE EXPERIENCE in consortium; reliable assessment of performance Current status: coking issue; flux in low partial pressure difference? Benefit for higher T ?

Fabrication and design

Electroless plating

Sputtering

Electroplating

MOCVD/CVD/PVD

Spray pyrolysis

Wet impregnation

….

Most methods manufacture the dense Pd layer directly on the support

Critical thickness to obtain a dense metal layer which depends on surface roughness and pore size in support’s top layer

High support quality: narrow pore size distribution + no surface defects

Pd-alloy fabrication methods

Interdiffusion barrier

Porous stainless steel or ceramic support

Pd-based membrane

Materials and Chemistry 7

SINTEF two-step membrane preparation

Pd-Ag target

Pd-Ag membrane

Ar-ions

Pd +Ag Pd +Ag Membrane preparation

on Si support by

magnetron sputtering

Membrane pull-off

from Si support

a) Free standing

membranes

b) Microchannel

supported

membranes

c) Composite membrane

1

2

high vacuum

Bredesen R, Klette H,

US Patent 6086729, 2000

(a)

(b)

(c)

Materials and Chemistry 8

Tubular Pd-alloy membrane manufacturing

Deposition of thin Pd-

alloy film on silicon wafer

Membrane pull-off

from Si support

Application on

porous support

Lab-scale composite

membrane preparation

50 cm up-scaled

membranes

Materials and Chemistry 9

Membrane and module design used in CARENA for "real

testing"

Pd-Ag films supported on micro-channels: reduction of polarisation resistance

Channels / slits between 0.2 and 1mm

No influence of permeate support side

High membrane area relative to the gas volume

Limiting effect of concentration polarisation

A.L. Mejdell, M. Jøndahl,

T.A. Peters, R. Bredesen,

H.J. Venvik., J. Membr.

Sci., 327 (2009) 6-10.

SEM: large plastic deformation shows

the high mechanical strength

Depth channels:

28 m

Film thickness:

~2 m

Materials and Chemistry 10

Co-sputtering enables to prepare various geometries and scales

Pd

Pd-Cu

Pd-Au

Pd-TM

Pd-Cu-TM

Pd-Au-TM

Co-sputtering enables to prepare binary and ternary alloy composition

Flexibility of manufacturing …

EDS [wt.%] Pd Ag Cu

Pd-Cu-Ag1 70.6 14.5 13.9

Pd-Cu-Ag2 66.6 14.3 19.1

Pd-Cu-Ag3 61.4 12.7 25.9

Pd-Cu-Ag4 58.0 11.7 30.3

Pd-Cu-Ag5 48.0 10.7 41.3

Materials and Chemistry 11

XRD: example of Pd-TM alloy membranes

FEG-SEM: Element mapping of cross-section of Pd72Cu25Au3

… for tuning of properties

Single phase fcc structure

No contaminant observed

Strong preferential orientation in

<111> direction

TM is substituting Pd in the fcc

lattice: unit cell varies and H2

solubility and diffusivity too

Homogeneous distribution of

metal components

Peters, T.A., et. al., J. Membr. Sci., 383, 2011, 124.

Summary 1

• Pd-based membranes fabricated by sputtering

– Thin membranes with high mechanical strength

– Various alloy compositions available

• Design of membrane module

– Tubular membranes for scaling up

– Micro- channels for real testing conditions

Ceramic conducting membranes

CH4 +

H2O

H2O+

CO2

Air

N2 + H

2O

+ H2

4 e-

4 H+

Catalyst

Membrane

2O2–

4e–

Permeate side: Low p(O2)

Feed side: High p(O2)

Membrane

Hydrogen transport membranes Oxygen transport membranes

EU FP7 ICAP

EU-7FP CARENA (Contract no.: 263007)

BIGCCS

H2 transport membranes

Activities in CARENA beyond SOA:

• New HTM materials

• Testing symmetric membranes in relevant conditions

• Shaping and scalability of membrane production considered

High stability at high T; not (less) sensitive to coking than Pd based membranes; High flux and high stability difficult to achieve Current status: button cell samples; Reference: SrCe1-xYxO 3 perovskite membranes

Fabrication and design

O2 transport membranes

Activities beyond SOA: • Materials development

• Manufacturing processes: scalability?

• Advanced characterisation tools

High flux membranes at T > 750C; Scalability of OTM membranes done by 2 large consortia in USA ; long term stability of high flux membranes problematic due to cation diffusion + stability in C containing atmosphere Current status : search for high flux membranes and fabrication of thin films

Fabrication and design

HTM: mainly small disk shaped membranes

Statoil: OTM

module

Air Products:

OTM module

SINTEF

OTM) scaled up production

SINTEF

8-10 microns

10 cm length (9 mm diameter)

50 microns

Statoil

Status of development

– Dense layer: lower L higher flux

– Porous support: no pressure drop

– Surface area as large as possible: improved kinetic exchanges

Requirements for membrane preparation

Wet ceramic coating and submicron-sized powders

Use of pyrolyzable fillers

Small grains; use of porous catalytic layers

22ln

16

2ln

2ln

2 O

ionel

ionelO p

LF

RTJ

IIOp

IOp

Membrane by tape-casting

Co-lamination @ T and P

Asymmetric membrane (one side polished)

Sintering procedures

Sintering

Support by tape-casting

Lamination @ T and P

Annealing

Spray-, dip- or spin-coating

Asymmetric membrane

Sintering procedures

Sintering

Suspension

Enable thin membranes

Controlled thickness typically > 20 microns

Enable optimization of supports

Planar membrane fabrication (OTM and HTM)

Support without filler

porosity = 50% porosity = 11%

Spin coating

m

Support with 5 % starch

Support with 5 % starch

porosity = 50%

Tape-casting

m

Planar membrane fabrication (e.g. OTM)

20

Effects of supports

Thickness of the selective layer = constante = ~30 microns

0,0E+00

2,0E-04

4,0E-04

6,0E-04

8,0E-04

1,0E-03

1,2E-03

1,4E-03

1,6E-03

1,8E-03

0,75 0,8 0,85 0,9 0,95

1000 T-1

/ K-1

P (

mL

.cm

-1.m

in-1

)

Support: 5% starch

Support: 10% ammonium oxalate

Support: 7.5% ammonium oxalate

Support: no filler

Ea ~ 47.5 kJ.mol-1

Feed:Air

Permeate: Ar

Ramp: 60 ºC/h

Ea ~ 53.8 kJ.mol-1

On the preparation of asymmetric membranes by tape-casting and co-sintering process, Journal of Membrane Science, Volume 326, Issue 2, 20 January 2009, Pages 310-315 M.-L. Fontaine, J.B. Smith, Y. Larring, R. Bredesen

Tubular membrane fabrication (OTM and HTM)

Paste preparation Extrusion of tubes Coating and sintering: membrane length max 1m

Support

Ceramic powder

Binder solution

Miller: several kgs

of feedstock

Ram extruder

Paste

Asymmetric sintered membrane of La0.87Sr0.13CrO3

10 microns

Dip-coating of tubes

Sintering

Membrane preparation at SINTEF (OTM and HTM)

Conditioning

Additives: fillers

Milling

Additives: water, dispersant, binder,

lubricant etc…

Mixing

Extrusion

Drying of samples

Porous supports

Suspension: oxide, solvent, dispersant,

binder

Mixing

Dip-coating, spray-coating

Sintering

Asymmetric membranes

SUPPORT FABRICATION COATING and SINTERING OF DENSE LAYER

Quality check

Quality check

Annealing T < 1300°C

Quality check

ASYMMETRIC MEMBRANES

Commercial powders

Starches Chitosan Tapioca …

SINTEF binder solution

Rheology of paste

Specific surface area (BET)

Dilatometry analysis: TEC, annealing

treatment

Hg porosimetry

Gas permeation

White light interferometry:

topography Microscopy

(SEM; FEG SEM)

X-ray diffraction (in situ): structure

Laser diffraction : particle size distribution

Potential zêta

Characterization &

QA of products

• Several green fillers available

• Thermal decomposition in air at low temperature with no residue

• No need for various conditioning steps of the ceramic powders

• No need of asymmetric structure of the support

• Fairly direct control of pore volume, pore shape and distribution

23

Pore formers (PF)

24

24

Agar agar

Ammonium oxalate

Chitosan

PF→ paste rheology →

extrusion parameters →

quality of supports

Support's porosity → gas

flow + roughness

Coating → quality (defects),

thickness 15 microns

< 10 microns

8-10 microns

10 cm length (9 mm diameter)

Advantages of using pore formers

• Small pores of less than 1 microns due to partial sintering of grains

• Volume adjusted by sintering treatment and green density

• Large pores of 5 to 10 microns (or more) due to burnout of fillers

• Volume adjusted by filler content in green state

Corn starch

Two main distributions of pores:

Microstructure and roughness

Surface of the tubes

explored by white

light interferometry

Rheology of pastes

strongly affected by

pore former content:

complex system

Roughness of the

tubes

Pores due to

burnout of

pyrolyzable

fillers

Pre-annealed porous tube:

Average roughness: 2,27 µm

Coating

Good coverage of

large pores

Porous tube coated and sintered:

Average roughness: 210 nm

Coating

Impurities (Mg, Al) rich particle

Crack

Thickness ~38 µm

Thickness ~24 µm

Thickness ~12 µm

Same porous supports

Presence of impurities: Leakages Cracks due to different

thermal expansion Effect more severe for

thinner films: clean room needed

22ln

16

2ln

2ln

2 O

ionel

ionelO p

LF

RTJ

IIOp

IOp

Impurities versus performance

Air

O2 g

Leakage

Decrease in the oxygen partial pressure gradient

Decrease in the oxygen flux +

Dilution with nitrogen

N2 g

Summary 2

• Various designs of membranes investigated in CARENA

• High quality membranes needed to obtain reliable performance