Development of Agglomerated - PowerPoint Presentation

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Development of Agglomerated CO2 Sorbent with Enhanced Chemical and Mechanical Stability for Hydrogen Production

Saima Sultana Kazi, Johann Mastin, Julien Meyer, Cristina Sanz PinillaDepartment of Environmental TechnologiesInstitute for Energy Technology, P.O.Box 40, N-2027, Kjeller, Norway

TCCS-8, Trondheim, 16-18 June 2015

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Options for hydrogen production

TCCS-8, Trondheim, 16-18 June 2015

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Steam methane reforming (SMR)The most dominant H2 production from Natural gas / Fossil fuel

Reforming: CH4 + H2O CO

+ 3H2

H= 206

kJ mol

-1

WGS:

CO

+ H2O CO2 + H2 H = - 41 kJ mol-1Highly endothermic reactionTypical reaction conditions: 800-1100 oC, 20-30 barHigh temperatures: Sintering, coke formationNi is chosen as catalyst

TCCS-8, Trondheim, 16-18 June 2015

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Sorption enhanced reforming (SER)Advantages:

Higher hydrogen yields in a single stepNo need for shift reactors and CO2 absorption-desorption columns

Lower operating temperatures

Only traces of CO

Production of relatively pure

CO

2

Potential for cost & energy savings

Steam reforming: CH

4

(g) + H

2O (g) CO (g) + 3H2(g) H = 206 kJmol-1Water-gas shift: CO(g) + H2O(g) CO2(g) + H2

(g) H = – 41 kJmol

-1

Carbonation

:

CaO(s)+ CO

2(g) CaCO3

(s) 

H =

–178.2

kJmol

-1Overall: CH4(g) + 2 H2O(g)+ CaO(s) CaCO3 (s) +4 H2(g) H = – 13.2 kJmol-1

In situ

removal of CO

2

, shifting the equilibrium to the product

side and resulting in higher hydrogen yield

TCCS-8, Trondheim, 16-18 June 2015

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Mechanism of carbonation reaction

Heterogeneous reaction

with product layer

formation

CaO

(s

)

+CO

2

(g

) CaCO3(s)

Reaction rate control

Fast

kinetic stage

Slow

kinetic stage

Diffusion control

CaO

CO

2

Dense

CaCO

3

layer

Small CaO

particles

almost

fully

convert

to CaCO

3

Large/

sintered

particles

will

keep

a unreacted

CaO

core

during

carbonation

Sintering

of CaCO

3

is enhanced at

high

temperature

by CO

2

and steam

TCCS-8, Trondheim, 16-18 June 2015

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CO

2 sorbent

High

CO

2

- sorption capacity

Reduced

bed

inventory

Mechanical and thermal

stability

Reduced sorbent make-up stream

Fast capture and regeneration kinetics

Low

production and recirculation

costs

Stable

in

high/low steam partial pressure

Compatible with catalyst

TCCS-8, Trondheim, 16-18 June 2015

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Loss

of

absorption

capacity

during cycling (sintering)

Sub-optimal mechanical

stability

For

pre-combustion

applications:

Sulphur removal from raw material is often needed Still do not match catalyst lifetime Separation/segregation problems when sorbentand catalyst are mixedNatural calcium-based sorbents: calcite and dolomite

Good availability and low cost

Large absorption capacity and satisfactory reaction kinetics

Proven SER hydrogen

yields up to 95+ vol%

Use of an inert solid to reduce sintering of CaO particles and increase the chemical and mechanical stability of the material

Al

2

O

3

, MgAl

2O4, Ca12Al14O33, SiO2, CuO, CaTiO3, ZrO2 etc…

TCCS-8, Trondheim, 16-18 June 2015

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Hydrothermal synthesisHeating the reactants in water at high

pressure and temperatureClose system e.g. a teflon lined autoclaveWater function both as pressure transmitting medium and as a solvent

Advantages of

hydrothermal

synthesis

Quite

low

temperature

Products are homogeneous in composition

Easy to control the purity, composition, size Cost effectiveTCCS-8, Trondheim, 16-18 June 2015

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Hydrothermal synthesis equipments

Pressurized reactor

(600 mL) with pressure, temperature and flow control with optional gas bubbling,

acid resistent

~100g of materials

can

be prepared

A

utoclaves

(50 mL) with pressure (up to 200 bars), temperature (200

o

C) and flow control~10g materials can be preparedTCCS-8, Trondheim, 16-18 June 20159Slide10

Hydrothermal synthesis of synthetic sorbents

In aqueous solution, 150 oC, 1-5h, Solid/Liquid= 33Ca(OH)2 + 2Al(OH)3

+ 2H2

O



Ca

3

Al

2

[(

OH)

4]3 (Hydrogarnet)T > 350 oC7Ca3Al2[(OH)4]3  9CaO + Ca12Al14O33 + 6H2O

(Mayenite)

Uncalcined

Calcined at 1000

o

C, 1h

Ca

(OH)

2

/hydrogarnet powders

Temperature

TCCS-8, Trondheim, 16-18 June 2015

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Agglomeration of hydrothermal sorbent powdersRequirements

:To produce uniform granule mixturesGenerate specific

size, shape,

porosity

and

density

Good

mechanical

strengthTCCS-8, Trondheim, 16-18 June 201511Slide12

Agglomeration techniques

Spray

drying

High

shear

agglomerator

Spraying

of

ceramic

slurry

Spherical particles Lower

bulk density

High

energy

mixing

and

granulation

Near

Spherical

particles Good control of particle sizeHigher bulk densityFluidized bed agglomeration

Spraying

of

liquid

binder

on

fluidized

powderSpherical

particles Low bulk density

TCCS-8, Trondheim, 16-18 June 2015

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High shear agglomerationLiquid binder as a solution is used (

wet granulation) Binder is dispersed

by a

rotating

blade

which

provides

shearing

forces in the powder massSolvent (water) evaporates from the binderInterparticle bond strengthen and powder particles stick together and larger granules are formed

TCCS-8, Trondheim, 16-18 June 2015

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Agglomerated hydrothermal particles

cm

Sorbent :

Hydrothermal

dried

powder

Agglomeration conditions:

Impeller

speed: 1000

rpm

Chopper speed: 3600

rpmBinding agent: 5 % polyethylene glycol (PEG 4000) in waterTCCS-8, Trondheim, 16-18 June 201514Slide15

SEM pictures

of agglomerated hydro_ sorbent

TCCS-8, Trondheim, 16-18 June 2015

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Mechanical properties of agglomerated sorbent

Digital Force Gauge

SHIMPO FGV-10X

Measurements of crushing strength

Sorbent

Median

crushing

strength (N)

Limestone

(Verdal)_

uncalcined

7.0Limestone (Verdal)_calcined1.6Hydrothermal _agglom11.4Sol-gel _agglom13.4TCCS-8, Trondheim, 16-18 June 2015

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High

chemical stability for sorbents with more than 60 wt% mayenite

CO2

uptake

: 30g (CO

2

)/100g sorbent / >95%

conversion

of

available

CaO

4 times the CO2 uptake of limestone after 40 cyclesTGA multi-cycling of the hydrothermal sorbentCarbonation: 600 °C for 10 min; 15 vol % CO2, 47 vol % H2O balanced in N2 , Regeneration: 21

vol % CO2, 77 vol % H2O, balanced in N2

, 850 °C for 3 min

Hydrothermal sorbents (pelletized)

TCCS-8, Trondheim, 16-18 June 2015

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Agglomerated sorbentsSlide18

Long-term chemical stability

No loss of

reaction

kinetics

in severe calcination conditions

>95%

conversion

of

available

CaO

Micro-porous structure of the solid is maintainedCarbonation: T= 6000C, 15 vol % CO2, 47 vol % H2O TCCS-8, Trondheim, 16-18 June 201518After 40th cycleSlide19

H

2

production by SER using agglomerated hydrothermal sorbent

Multi-cycle tests show stable enhanced production time with max. H

2

production

>

95 mol%

H

2

is

produced in each

cycleTCCS-8, Trondheim, 16-18 June 2015

Pre-

breakthrough

Breakthrough

Post-

breakthrough

H

2CO

2

19

Sorbent: 35

g sorbent, Catalyst : 8,75 g. Sorbent/catalyst: 4, S/C: 4, FCH4 =120 ml/ min, T= 625 °C and P= 1 bar. Regeneration: T= 800 °C, FN2 = 475 ml/min, FH2 = 25 ml/minSlide20

Pelletized vs agglomerated sorbent in SER reaction

Sorbent: 35 g sorbent, Catalyst : 8,75 g. Sorbent/catalyst: 4, S/C: 4, FCH4 =120 ml/ min, T= 625 °C and P= 1 bar. Regeneration: T= 800 °C, FN2

= 475 ml/min, FH2 = 25 ml/min

Production

time

is

slightly improved

for the agglomerated

sorbent compared to pelletized (50MPa) sorbent

Better micro-

porosity contributes to a longer production time for agglomerated sorbent

H

2

CO

2

20

TCCS-8, Trondheim, 16-18 June 2015Slide21

Effect of space velocity on SER performances

Sharper

breakthrough

is

obtained

when

increasing

gas

velocity

Good SER performances even at higher gas velocityLess than 2 mol% CO2 is released with >95mol% H

2 production

H

2

CO

2

TCCS-8, Trondheim, 16-18 June 2015

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Sorbent: 35 g sorbent, Catalyst : 8,75

g.

Sorbent/catalyst

:

4, S/C: 4, FCH4 =120 ml/ min, T= 625 °C and P= 1 bar. Regeneration: T= 800 °C, FN2 = 475 ml/min, FH2 = 25 ml/minSlide22

IFE

developed

a

new

simple and

low-cost

synthesis

method

for

production

of CaO-based CO2 sorbent with high chemical stability (4 times the CO2 uptake of limestone)An agglomeration process has been developed

for particle production with

enhanced mechanical

properties (

7 times

the crushing strength of calcined limestone)

Agglomerated sorbent materials were successfully tested in a fixed bed reactor for H2 production by SER

Multi-cycle

operation confirmed

the

excellent

stability of the sorbents, more than 95 mol% H2 was produced in a single reaction stepDevelopment of combined sorbent-catalyst particles for reduced CAPEX/OPEXUp-scaling

of

production method

Test of the sorbent

material in relevant SER process conditions (SER

fluidized bed pilot plant at HyNor Lillestrøm, Norway)

Conclusions and further work

TCCS-8, Trondheim, 16-18 June 2015

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Acknowledgements

Material and

Process

Technology Group - Department of

Environmental

Technology, IFE

www.ife.no/depts/envtech

Thank you for your attention!!

TCCS-8, Trondheim, 16-18 June 2015

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