Ceramic Membranes in Energy And

8/2/2019 Ceramic Membranes in Energy And

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CERAMIC MEMBRANES IN ENERGY ANDENVIRONMENT RELATED APPLICATIONS

V.T. Zaspalis

Research at the Center of Research and Technology-Hellas

Center for Research and Technology-Hellas

Chemical Process Engineering Research Institute

Laboratory of Inorganic Materials


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CONTENTS

What is a membrane

Low Temperature Applications :

Separation of gas mix tures

Water treatment

High Temperature Applications:

Environmental friendly combustion ofnatural gas

Hydrogen from renewable sources

CONCLUSIONS


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What is a membrane

A ceramic membrane is a thin semi-permeable film made of inorganicoxidic materials

It can be porous so that selective transport takes place though the poresand through various mechanisms

It can be non porous so that selective transport takes place throughcrystalline lattice diffusion

It can be self-supported when is thick and strong enough, or supported onsubstrates when is thin and mechanically weak

selectivity of permeating substances

F l u x

t h r o u g h

porous systems

dense systems

research goals


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34cm

8mm 14mm

What is a membrane

n a n o p

o r o u

s l a y

e r

mesoporous bridgelayers

m a c r o p o r o u

s

s u b s t r a t e


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What is a membrane

Ceramic membranes at CERTH are prepared:

Step 1:Synthesis of stabilized nanoparticledispersions by metal-alkoxide hydrolysis

Step 2:Membrane layer formation by dip-coating onporous substrates

Step 3: Eventual further pore surface modification or size reduction by wet impregnation or vapor

deposition techniques


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Porous membranes, Separation of gas mixtures

Scientific principle I: Knudsen law

In simple words: At nanopore level small molecules move faster than large ones

This principle can form the basis for the development of separationtechniques where mixtures of light (e.g. hydrogen) and heavy (e.g.hydrocarbons) components can be enriched in the light components

L

P

RT

vr A

dx

dC ADF mmk K K

== 3

2 M RT vm

8=


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0.E+00

5.E-09

1.E-08

2.E-08

2.E-08

3.E-08

3.E-08

4.E-08

4.E-085.E-08

5.E-08

0.E+00 1.E+05 2.E+05 3.E+05 4.E+05 5.E+05 (Pa)

F ( m o

l s - 1 m - 1

P a - 1

)

Hydrogen

Helium

Nitrogen

Hydrogen Propane Mixture50/50

M e m

b r a n e

Hydrogen Propane Mixture82/18


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Scientific principle II: Kelvin law

Vapor pressure of liquid concave in a pore is lower than that of thesame liquid on a flat surface, it therefore condenses much earlier

r P

P

M

RT t

cos2ln

0=

This principle can form the basis for the development of separationtechniques on mixtures containing a condensable and non-

condensable and non-soluble component


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5

5,5

6

6,5

7

7,5

8

20 30 40 50 60Temperature ( oC)

S e p a r a

t i o n

f a c

t o r

0

1

2

3

4

5

6

p e r m e a

b i l i t y x

1 0 1 5

m o

l / m

/ s / P a

Propane C 3H8Propylene C 3H6

Similar molecules very

difficult to separate

C 3H8: 50C 3H6: 50 C 3H8: 12

C 3H6: 88

C 3H8: 50H2: 50 C 3H8: 98H2: 2


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Scientific principle III : Activated microporous diffusion

The pore is reduced down to the molecular dimensions and separation occurs bysieving

Vapor deposition techniques

H2: 50 CO 2: 50H

2: 98.8 CO

2: 1.2


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Porous membranes, Water treatment

0

1

2

3

4

5

6

0,00010,0010,010,11

d p ( m)

Pure Water

Monovalent ions

Multivalent ions

Viruses

Bacteria

Suspended solids

3 layers

1st

2nd

3 rd4 th

4 layers 5 layers


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Porous membranes, Water treatment

Purified water product

As: 1ppm

Fe 2O 3 nanoparticles

cad e

Qt K QQ

ln1

ln =

0

1

2

3

4

5

6

7

0 20 40 60 80 100 120 140Contact time, min

l n ( 1 / ( Q

e - Q

) )

Removal of toxic metals (As, Cr) from w ater

0,01

0,1

1

feed product

A s

i o n c o n c e n t r a

t i o n

( p p m

)

Current maximum allowablelimit 50ppb

Fe: 2000 ppm Fe: 0,001 ppm

25nm 25nm


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Dense Membranes, Hydrogen from renewable sources

One of the most promising and long-term sustainable routesfor the production of energy is:

H2O H 2 + 0.5 2

The process currently under intensive research is the so-

called RedOx process hydrogen production

0 1 2


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Our research-proposal is based on a dense oxygen conducting membrane reactor

H2O

H2

Membrane

Mixed Conductor

Vo, e

O o

c o m p a r t m e n

t 1

c o m p a r t m e n

t 2

O 2

..Ooo21..2

Dense Membranes Hydrogen from renewable sources


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0.0E+00

5.0E-09

1.0E-08

1.5E-08

2.0E-08

2.5E-08

3.0E-08

0 5000 10000 15000 20000

Time (s)

H 2

I o n

C u

r r e n

t ( A )

0 1 2 3 4 5 6

Time (hr)

I n a c

t i v e s t a

t e

Hydrogen in compartment 1, T=900 oC, P 1=P 2=1bar

CO in (compartment 2)

CO off

(activation)

baseline (0 mmol H 2 m -2 hr -1)

steady state (~13 mmol H 2 m -2 hr -1)H2O 1/2O 2+H 2

CO +H 2O CO 2+H 2steady state: (~39 mmol H 2 m -2 hr -1)


Dense Membranes Environmental friendly combustion of natural gas


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Dense Membranes, Environmental friendly combustion of natural gas

H2O

H2

Membrane

Mixed Conductor

Vo, e

O o

c o m p a r t m e n

t 1

c o m p a r t m e n

t 2

O 2

.. Ooo2

1..2

Air Methane (CH 4)

CH 4+2O 2 CO 2+2H 2O + Energy

pure CO 2 STORAGE



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-50

0

50

100

150

200

0 20 40 60 80 100 120

Reactor loop number O x y g e n a

v a i l a b l e i n t h e s o

l i d f o r r e a c t

i o n

C H 4

p i c k s u p o x y g e n

A i r

d e l i v

e r s o x y

g e n

La 0.7 Sr 0.3 Cu 0.05 Fe 0.95 O3Material:

T=980 oC


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CONCLUSIVE REMARKS

Porous ceramic membranes (specially modified to the nanoporous region) cangive high separation factors and give rise to the development of efficient process,

in particular for the separation of hydrogen

Porous ceramic membranes can provide technological solutions to many water treatment case-problems. The technology is quite mature to leave the laboratories

Dense oxygen conducting membranes can give rise to the development of greenhigh temperature processes towards either hydrogen production from renewable

sources or CO 2-capture oriented combustion of natural gas


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ACKNOWLEDGEMENTS

Research staff of the Laboratory of Inorganic Materials

L. Nalbandian

S. Sklari

A. Evdou

A. Pagana

Technical staff of CERTH:T. Tsilipiras

N. Georgiou

A. Moudiotis

The vapor deposition modifications of the membranes are being done incooperation with:

Prof. G. Sakellaropoulos, dr. S. Kaldis and S. Koutsonikolas

of the department of Chemical Engineering

of the Aristotle University of Thessaloniki

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Ceramic Membranes in Energy And