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Dynamische Methoden in der AdsorptionstechnikProf. Dr. habil. Reiner Staudt

Hochschule Offenburg

Fakultät für Maschinenbau und Verfahrenstechnik

Hochschule Offenburg University of Applied Sciences


Gliederung

• EinführungDefinitionen, Begriffe

• Poröse FeststoffeMaterialcharakteristik

• IsothermenExperiment,Isothermengleichungen

• Kinetikeffekt. Transportkoeffizient

• Wärmeisosterische Wärme

• GemischadsorptionExperiment, Modelle

• Reale AnwendungenTSA, PSA, Wärme

30. Mai 2017 Prof. Dr. habil. Reiner Staudt 2


AdsorptionIsothermal Equilibrium

30. Mai 2017 Prof. Dr. habil. Reiner Staudt

pi (H2O)ni (H2O)

3


Adsorption on surfaces / separation effects

Technical usable effects

Thermodynamic effect (differences

between the sorption capacities)

Knowledge of Isotherms

Kinetic effect (differences between the

sorption velocities)

Knowledge of transport coefficients

Steric effect (molecular sieve effect)

Knowledge geometrical parameters



Adsorption process - Input Data

IsothermsKinetics

Co-adsorption

Feed flow Product purity

Cycle duration, Dimension of adsorber…

Prediction of breakthrough curves

Simulation model

Heat data


Porous Solid

5


Modeling – Unknown Parameter

Mass Balance

Mass Transfer Coefficienteffk

1) W. Kast, Adsorption aus der Gasphase, (1988)2) F.V.S. Lopes et al., Sep. Sci. Technol. 44 (2009)3) V.S. Prasad et al., Int. J. of Heat and Mass Transfer 45 (2002)

Energy Balances

h

axD Axial Dispersion Coefficient

in c Adsorbed amount

Parameter Get from Alternative

Breakthrough on fixed bed(for example inert material)

Fitting the model onbreakthrough Curves

From Isotherms

Calculation from gas velocity,particle size and otherParameters 1,2)

From Uptake rateexperiments?

g

w

U

,h

Heat of adsorption From Isotherms

Dispersion Coefficient

Heat transfer Coefficients Fitting the model onbreakthrough Curves

Experiments on packedbeds (Breakthrough exp.) 3)

Set Zero to simplifyenergy balance

Fitting the model onbreakthrough Curves


Breakthrough exp.

Breakthrough exp.

6


Modeling – Unknown Parameter

Thermophysical Properties

Heat capacity ofgas phase

PGc

PSc Heat capacity ofporous material

iq

Density of gas phase

Parameter Get from Alternative

Literature

Literature

Equation of State

Experiments

Experiments


Experiments

Heat capacity ofwall

W

W WL Surface to Volume ratio

Literature

Geometry

Experiments

7


Porous materials

Activated Carbon

Zeolite

Molecular sieve

Silicagel

MOF



Classification of pores


Submicropores d ≤ 0,4 nm

Mikropores 0,4 < d ≤ 2,0 nm

Mesopores 2,0 < d ≤ 50 nm

Makropores d > 50 nm


Quelle: VDI-Richtlinie 3674http://www.chemgapedia.de

10


Characterisation of porous materials


• Pore size distribution: DIN 66135

• BET surface, pore radius: DIN 66135

• Iodine number: ASTM D4607 – 94

• Water content: DIN 51718

• Ashes content: DIN 51719

• Density (bulk, Helium)

• Abrasion, Paricle size distribution

• Benzole Adsorption at rel. Pressure: 0.9, 0.1, 0.01, 0.001

• VDI-Richtlinie 3674



Excess amount adsorbed

Total mass in system mtotal 12 + 4Mass in gas phase mf 8 + 4Gibbs excess mass mGE 4

Adsorbens

P, T, P, T,

Adsorbens

without adsorption

with adsorption

f f ' sGEm V V

Gibbs definition ofexcess amount adsorbed



Excess amount adsorbed

Distance from surface

De

nsi

ty

Poroussolid

Surf

ace

f

(z)a

Adsorbed phase Gas phase

I

II III

Total mass in system mtotal (I + II + III)Volume of Gas phase Vf = V – VSolid

Mass in gas phase mf (II + III)Gibbs excess mass mGE = mtotal – mf (I)



Isotherms

- Isotherms of pure components- Pressures up to 3.5 MPa- Temperature range: 260 to 700 K

Breakthrough Curves

- Breakthrough curves- Pressures up to 1.0 MPa- Ambient temperature

Experiment



Start: Calibration of instrument→ Volume of Sample→ Dead volume

Step 1: Measurements without sample→ Value of unloaded microbalance→ Value of unloaded adsorber

Step 2: Installation of sample

Step 3: Activation / regeneration of sample→ Mass lost of sample by desorption

Procedure of measurement I

31. Mai 2017 Prof. Dr. habil. Reiner Staudt 1530. Mai 2017 Prof. Dr. habil. Reiner Staudt 15


Regeneration Process:• Time (cp. technical process)• Temperature, Pressure (cp. technical process)• Gas flowIn Dynamic experiment:• Close to technical application / real process

Step 4: Measurement with non-adsorbing gas:→ Helium volume→ Gas velocity

Helium measurement = reference measurement

Procedure of measurement II

31. Mai 2017 Prof. Dr. habil. Reiner Staudt 1630. Mai 2017 Prof. Dr. habil. Reiner Staudt 16


Procedure of measurement III

31. Mai 2017 Prof. Dr. habil. Reiner Staudt 1730. Mai 2017 Prof. Dr. habil. Reiner Staudt

Step 5: Measurement of adsorption isotherm / breakthrough curve→ Excess amount adsorbed

Adsorption equilibrium→ Time (cp. technical process)→ Constant Microbalance signal

17

Step 6: Measurement of desorption / regeneration→ regeneration time and conditions


balance

• time-resolution 1 sec

• mass-resolution 10 µg

• temperature RT-500 °C

pressure transducers

• 0.01 mbar – 10 mbar

• 1 mbar - 200 mbar

• 200 mbar - 30 bar

temperature sensor

• PT 100 sensor

vacuum

• turbomoleculare pump

micro balance

magnetic coupling

Sample

vacuum pump

gas inlet

Instrumental setup



AdsorptionChoice of zeolite


0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 500 1000 1500 2000 2500 3000

X/(g

/g)

p / Pa

Wasserisothermen bei T = 353 K

4ABF bei T = 353 K

13XBF bei T = 353 K

NaMSX bei T = 353 K

NaY bei T = 353 K

NaYBFK bei T = 353 K

19


INCurves120


as f

fflow col

m V

m *t V *

Calibration of instrument: volume, WLD, …

Measurement: concentration c(t), massflow mflow

and time t

20


Breakthrough curves

Measurement of breakthrough curves

• on approx. 100 g sample

• up to 10 bar, 3 different gas inlets ( 2 x 5 NL min-1, 1 x 1 NL min-1)

• detection of gas composition with thermal conductivity detector

• measurement of temperature profiles (4 sensors)

Dosing unitAdsorber with 4

temperature sensors

Detector

Pressure control

Heating system




TE 1TE 2TE 3TE 4WLD-SignalGaseingangsfunktion

Zeit

C/C

0

Tem

pera

ture

nTE 1TE 2TE 3TE 4WLD

Eingangsfunktion

TE 2

TE 1

TE 3

TE 4

Dynamische Messanordnung für Untersuchungen an Festbett INCurves 120,Dr. Andreas Möller, Faltblatt DBK (Brochüre INC); 2013

INCurves120

22


Reactor without isolation

30. Mai 2017

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14

∆T

/ K

Time t / h

T1 / °C T2 / °C T3 / °C T4 / °C

TE 2

TE 1

TE 3

TE 4

Prof. Dr. habil. Reiner Staudt 23



FascinationZeolite - Water

24


Heat of Adsorption - Experiment


Quelle: Zimmermann/Keller Universität Siegen

25


Isosteric heat of adsorption


2 2st 1 2

2 1 1 1 xi

p cR T Tq ln

T T p c

cp. Clausius Clapeyron


Heat of adsorption

Beladung n

Adsorbat-Adsorbens-WW

Laterale WW(Kondensation)

Inhomogene Oberfläche

2 2st 1 2

2 1 1 1 xi

p cR T Tq ln

T T p c



Zeolith

GrenzfilmTransportmechanismen:

Festbettdiffusion

• Grenzfilmdiffusion

• Porendiffusion

Linear Driving Force

Zusätzlich:

• Wärmetönung

Kinetics of Adsorption



30. Mai 2017

Gravimetric experiment

0

0.05

0.1

0.15

0.2

0.25

0.3

0 2 4 6 8

load

X/(g

/g)

time t / h

Uptake of Adsorption of water in zeolite NaYBFK 80% rel. hum.

T1 = 23,07621019°CT2 = 41,37786062°CT3 = 61,88455312°C

T1 = 296 K

T2 = 314 K

T3 = 355 K

Prof. Dr. habil. Reiner Staudt 29


Kinetics - Linear Driving Force

∆X concentration gradient

keff effective transport coeffizient



0

1

2

3

4

5

6

0 20 40 60 80 100

gas

com

positio

non

adsorb

er

exi

t/V

ol.%

time /min

breakthrough curves

transport coefficient for Adsorptiv 1 (1/min) : 20

transport coefficient for Adsorptiv 1 (1/min) : 2

transport coefficient for Adsorptiv 1 (1/min) : 0.2

Kinetics – Transport coefficient



* Bastos-Neto et al., Chem. Ing. Tech., 83 (2011)

0.0 1.2 2.4 3.6 4.8 6.00.0

0.2

0.4

0.6

0.8

1.0

AC D 55/2 C PSAmethane

C5

model

C1

C4

C2

C3

rela

tive

co

nce

ntr

atio

n(C

/C0)

time / 103

s

Hydrogen Purification - Results for methane

Feed Experimental run

vFeed = const. C1 C2 C3 C4 C5

Feed pressure / MPa 0.5 1.0 1.5 2.0 3.0

Feed molar fraction of CH4 / % 16.5 17.0 17.2 17.2 17.3

Feed flow rate / cm3 s-1 at SATP 0.74 1.49 2.23 2.98 4.47

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.350.0

0.5

1.0

1.5

2.0

2.5

3.0293 K

am

oun

tad

so

rbe

d/

mm

ol.g

-1

pressure / MPa

methaneAC CarboTech D 55/2 PSA



94,22547 g

T

T p

gas supply

vacuumpump

gas circulationpump

storagevessel 1

storagevessel 2

microbalance

sample

T

gaschromatograph

magneticcoupling

IS 1

IS 2

injectionsystems

Calibration:Volume of vessel & sampleholder, GC ...

Volume-Gravimetry:

Measurement: p, T, m

Calculation:

mfl1, mfl

2, m1, m2

Volumetry with GC:

Measurement: p, T, c

Calculation:

mfl1, mfl

2, m1, m2

Volume-Gravimetry & Volumetry with GC



CO/H2 Mixture on 5A Zeolite

Pressure p [MPa]

0 1 2 3 4 5 6 7

Ex

ce

ss

am

ou

nt

ad

so

rbe

d[m

mo

l/g

]

0

1

2

3

4

IAST: n = nCO + nH2

IAST: nCO

IAST: nH2

Experiment: n = nCO + nH2

Experiment: nCO

Experiment: nH2


T = 303 K, y(CO)=0.3

34


CO2/N2 an AK Norit R1, T = 298 K

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6 7

0.00.2

0.40.6

0.8

Exc

ess

am

ou

nta

dso

rbed

[mm

ol/g]

Pressure [MPa]

Conc. yCO2



Results - Influence of the input concentration

0 20 40 60 80 100 1200.0

0.2

0.4

0.6

0.8

1.0

time / min

rela

tiv

eco

nce

ntr

ati

on

1 bar - AdsorptionAC CarboTech:

D 55/2 C PSA - 38.29 gD 50/3 C PSA - 40.07 g

Concentration Increase



Results - Ternary Mixtures

0 600 1200 1800 2400 3000 36000.00

0.25

0.50

0.75

1.00

1.25

1.50

nitrogenmethanemodel

KÖSTROLITH 5ABF

rela

tive

co

ncen

tration

(C/C

0)

time / s

TA1TA2

0.00 0.03 0.06 0.09 0.12 0.150.0

0.2

0.4

0.6

0.8

1.0

TA2

TA2

TA1

KÖSTROLITH 5ABF

nitrogen

am

oun

tad

sorb

ed

/m

olkg

-1

pressure / MPa

SIPS fitIAST fit

298 K303 K

methane

TA1



Ternary Mixture CO2/CH4/H2 – AC CarboTech D 50/3 C PSA

0 10 20 30 40 50 60

0

2

4

6

8

10

12

14

16

18

20

time [min]

sig

nal[%

vo

l]

CarboTech D 50/3 C PSA: 41.05g / 14cmH

2: 155 mL/min

CO2: 35 mL/min

CH4: 10 mL/min

1 bar - Adsorption

1st

run - 30°C

2nd

run - 20°C

3rd

run - 20°C

4th

run - 19°C

0 10 20 30 40 50 60 70 80 90 100 110

0

2

4

6

8

10

12

14

16

18

20

time [min]

sig

nal[%

vo

l] 1st

run - 28°C

2nd

run - 20°C

3rd

run - 20°C

4th

run - 19°C

CarboTech D 50/3 C PSA: 40.05g / 14cmH

2: 200 mL/min

CO2

CH4

1 bar - Desorption



Results - Multicomponent system

0 10 20 30 40 50 600

2

4

6

8

10

12

14

16

18

20

time / min

sig

na

l/

%v

ol

1st

run - 295 K

2nd

run - 298 K

3rd

run - 295 K

4th

run - 296 KCarboTech D 55/2 C PSAH

2: 155 mL/min

CO2: 35 mL/min

CH4: 10 mL/min

0.1 MPa - Adsorption



0 20 40 60 80 100 120 1400

2

4

6

8

10

sig

nal

/%

vo

l

time / min

1st

run - 302 K

2nd

run - 297 K

3rd

run - 302 K

Koestrolith 5ABFH

2: 180 mL/min

CH4: 12 mL/min

CO: 8 mL/min2 MPa - Adsorption


Results - Multicomponent system

40


0 200 400 600 800 1000 1200 1400 160020

25

30

35

40Temperaturverlauf

Zeit in Sekunden

Tem

p.d

erT

herm

oele

men

tein

°C

31

N2 / CO2 / CH4 (10% / 40% / 50%) in AC Norit NR1 Extra

Mass AC = 75,9 g, p = 1,2 bar



Adsorption Isotherm Model


Dynamic equilibrium based on Langmuir theory• Langmuir Adsorption Isotherm• BET Isotherm• Tòth Isotherm• Sips Isotherm• Freundlich Isotherm• Virial equation

Thermodynamik in sense of Gibbs

Potential theory of Polanyi

42


Adsorption Isotherm Model


Dynamic equilibrium based on Langmuir theory

Thermodynamik in sense of Gibbs• Gibbs’sche Adsorptionsisotherme• Vacancy - Solution - Model (VSM)• Associating Theory of Adsorption (ATA)• Ideal Adsorbed Solution Theory (IAST) and

modification

Potential theory of Polanyi• Dubinin• Myers – Prausnitz – Dubinin – Approach (MPD)

43


Experiment – accuracy

Gravimetry Volumetry Breakthrough Gravimetry dyn.

Dm/m = 0.1 % Dm/m = 0.5 % Dm/m = 0.5 % Dm/m = 0.25 %

Pressure Temperature Mass Volume of sampleholder

Dp = 0.002 MPa DT = 0.01 K Dm = 0.01 mg DV = 0.0002 cm3

Volume of vessel Concentration Gas Flow Time

DV = 0.02 cm3 Dc = 0.1 % DVt =0.1 ml/min Dt =0.01 s



Choice of my experimental setup

Gravimetry

• Direct measurementof m, p, T

• Mass change duringsample preparation

• Uptake curve

• Adsorption isotherm(Kinetics)

Volumetry

• Direct measurementof p, T

• “Simple” apparatus

• Adsorption isotherm

• Corrosivecomponents

Breakthrough curve

• Direct measurementof c, p, T

• “Simple” apparatus

• Pure and Mixed gascomponents

• Adsorption isotherm

• Kinetics of process

• Small concentration

• Close to technicalseparation /regeneration



0

5

10

15

20

25

30

0 200 400 600 800 1000 1200 1400 1600

am

ou

nt

ad

so

rbed

pressure

T1

T2 > T1

A

DB

C

A to B: pressure swing / purge with intert gasA to D: temperature swingA to C: mix of both

Basics of adsorption technique / processes

Temperature swing process (TSA)

• Desorption by increase of T (A to D)

• Hot inert gas, Water vapor, Electrical

heating

Pressure swing process (PSA/VPSA)

• Desorption by decrease of p (A to B)

• PSA adsorption at higher pressures;

regeneration at atmospheric pressure(1)

• VPSA adsorption at higher pressures;

regeneration under vacuum (1)

Combined TSA-PSA

• Desorption by increase of T and

decrease of p (A to C)(1)

(1) D. Bathen, M.Breitbach, Adsorptionstechnik, Springerverlag, 2001



Adsorption isotherm @ 298 K, H2, CO2, CO, CH4, N2

Activated carbon Zeolite

0

10

20

30

40

50

60

0 500 1000 1500

Partial Pressure [mbar]

Am

ou

nt

Ad

so

rbe

d[N

l/k

g]

CO2

CH4

CO

N2

H2

0

10

20

30

40

50

60

0 500 1000 1500

Partial Pressure [mbar]

Am

ou

nt

Ad

so

rbe

d[N

l/k

g]

CO

CH4

N2

H2



Adsorptionsisothermen an AK

Prof. Dr. habil. Reiner Staudt

Druck p [MPa]

0 1 2 3 4 5 6 7

Exz

essad

so

rbatm

en

ge

nex

[mm

ol/g

]

0.0

2.5

5.0

7.5

10.0

12.5

N2

CH4

CO2

H2S

298 K

30. Mai 2017 48


Adsorption Isotherms of Ar, Kr, O2 and Xe



Adsorber zur Lösungsmittel-Rückgewinnung (TSA-CSA)

Fließbild und Foto:Silica VT GmbH

TSA-Festbett-Adsorber: Desorption mit Wasserdampf



Pressure swing adsorption


• Air separation into N2 (>99,9 %), O2 (< 97 %) or Ar

• Production / Cleaning of H2

• Separation of CO2 from biogas

• Drying of compressed air

51


Hydrogen – Production by PSA

Use Purity Requirements

Ammonia Synthesis < 10 ppm COX, X = 1,2

Compressed Gas < 10 ppm COX, 100 ppm CH4,< 200 ppm N2

Fuel Cells < 30 ppm CO

Electronics (Semiconductors) < 10 ppb N2, O2, CH4, CO, CxHy

Food Industry 3.1 – 5.5 (% Vol. H2)



Required Information

Hydrogen Purification

Isotherms

Heat of Adsorption

Heat capacities

Kinetics

Co-adsorption

Production Regeneration



Activated Carbons

Zeolites

CO2

CH4

CO

CH4

CON2

H2-rich mixture

Studied Samples2 Activated Carbons3 Zeolites 5A

Hydrogen Purification – PSA Unit


Pure H2


Measurement of Isotherms Measurement of Breakthrough Curves

Hydrogen Purification



1E-3 0.01 0.1 10.01

0.1

1

10AC D 55/2 C PSAmethane

Toth model at 298 KToth model at 303 KA seriesB seriesC series

am

ou

nt

ad

sorb

ed

/m

olk

g-1

pressure / MPa

A3

A2

A1

B1

B4

B2

B3

C5

C1

C4

C2C3

0.01 0.1 0.60.2

1

3

F4

F3 F2

F1

E3 E4

E2

E1E1Toth model at 298 KToth model at 303 K

KÖSTROLITH 5ABF

carbon monoxide

pressure / MPa

am

oun

tad

sorb

ed

/m

olk

g-1

Hydrogen PurificationValidation of the Experimental Breakthrough Curves

Lines are Toth fit based on gravimetrically measured resultsPoints correspond to measured breakthrough curves



Adsorption based gas separation processes (I)

Process Feed Product(s)

Air separation Air, dry, clean Nitrogen (N2)Oxygen

Pressure swingadsorption (PSA)]

Oxygen, Methan,Hydrogen

Air conditioning Air loaded with exhaust gases fromindustry, traffic, resi-dential heatingetc. N2, O2, H2O, CO2, H2S,aromatics etc.

Clean airN2, O2, (H2O)

Temperature swingadsorption (TSA)

Air purificationSolvent recovery

Air loaded withVOC (Volatile Organic Compounds),

BTX (Benzole, Toluene, Xylole),Smells, odors

Clean air (N2, O2, Ar)VOC, BTX



Adsorption based gas separation processes (II)

Process Feed Product(s)

Carbon dioxide removal Blast-furnace gasCO2, CO, H2, H2O

Syngas (H2, CO)

Drying of air prior topressurization

Humid air Dry air

Flue-gas purification Exhaust gases of power stationsN2, O2, CO2, SO2,NOx, etc.Hg from crematories, Isotopes nuclear

“Clean flue gases”N2, O2, H2O, CO2

Hydrogen separation Reforming gas, Blast-furnace gasH2, CO, CO2, CH4, H2O

Hydrogen rich gas(Syngas: H2, CO)

Natural gas enrichment ofmethane content

Raw gas from wellCH4, CO2, N2, H2S, CO, etc.

Town gasCH4, H2, CO



Wärmespeicher



Pilotanlage zur Wärmespeicherung


Möschle GmbH, Behälterbau, Ortenberg,

60


Pilotanlage

Möschle GmbH, Behälterbau, Ortenberg,


Befeuchtungssystem:

61


Heizen im Winter



Temperaturanstieg durch Adsorption von Wasser


20

25

30

35

40

45

50

55

60

65

70

0 50 100 150 200 250 300 350

Te

mp

era

tur

T/

°C

Zeit t / min

Adsorption von Wasser im Zeolith Köstrolith 5ABFK

T1

T2

T4

T5

T6

63


Mobiler Wärmespeicher



My Conclusion

Dynamic characterisation of adsorption process delivers:

1. Adsorption Isotherm

2. Transport coefficient

3. Heat production / Temperature change during process


Dynamic measurements are applicable for

1. Experimental simulation of real technical adsorption process

2. Wide range of pressure and temperature

3. Low concentrations, multicomponent gas,…

Simple and robust apparatus

65


Acknowledgement

We greatfully acknowledge

Lea Treick, Phillip Schandelmaier (Bach. Sc.)

Dr. A. Möller, Dr. J. Möllmer

Prof. Dr. Moisés Bastos Neto

Land Baden-Württemberg, Industry on Campus


BMBF - KMU Innovativ

66

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