j.u. keller , n. iossifova , w. zimmermann , f. dreisbach ... · pdf fileadsorption equilibria...

University of Siegen Institute of Fluid- & ThermodynamicsJürgen U. KELLER 06

Experimental Methods for Single- and Multi-Component Gas Adsorption Equilibria

J.U. Keller 1), N. Iossifova 1), W. Zimmermann 1), F. Dreisbach 2), R. Staudt 3)

1)Inst. Fluid- and Thermodynamics, University of Siegen,D-57068 Siegen, [email protected]

2)Rubotherm Präzisionsmesstechnik GmbHUniversitätsstr. 142, 44799 Bochum, Germany

3)Center of Non-Classical Chemistry, University of LeipzigPermoserstr. 1504318 Leipzig, Germany

Introduction

1. Volumetry / Manometry

2. Gravimetry

3. Oscillometry

4. Calorimetry

5. Impedance Spectroscopy

Hybrid Measurements

6. Volumetry / Gravimetry

7. Densimetry / Gravimetry

8. Densimetry / Volumetry

9. Manometry / Impedance Spec.

10. Conclusions

4 PB-1


Adsorptive 1

Adsorptive 2Adsorption(exothermic) Desorption

(endothermic)

Adsorbent

Adsorbate

Adsorption

4 PB-2


Gas Flow Porosimeter (He, N2, BET, 77 K)

1 Sample / Sorbent

2 Dewar vessel (N2, 77 K)

3 Mixing chamber

4 Thermal diffusivity detector (a)

5 Sorptive gas flow (original)

6 Reduced gas flow (changed)

7 Data display system (Ua)

4 PB-3


Experimental setup for volumetric-chromatographicmeasurements of multi-component gas adsorption equilibria

4 PB -4


Mass balances

Total mass (i)

Adsorptive’s mass (i)

* fi i im m m i 1...N

* * f * * *i i 1 N SVm w T,p ,w ...w V

f f Si i SV ACm V V V

(1)

(2)

(3)

f Si i i(1 3) : m V

*i i i SV i ACV V

f fi i N iw T,p,w,...w , w : GC

S SHe iV V m ... Gibbs excess mass

(4)

Volumetry / Chromatography (Closed Systems)

4 PB-4A


Adsorption equilibria of a CH4-CO2-N2 gas mixture on activated carbon ACR1. Data correlation:2-sites LAI

4 PB-5


Gas – Solid – Adsorption Equilibria :Volumetric – Chromatographic Analysis (N1)

4 PB -6

PCiA

GC

Impedance Analyzer

N2Ar

CO2CH4

FLOW

RATES

Gas Chromatograph

AnalysisFormulation

1 2 3 TF T

Sorbent MaterialSorbate

Sorptive Gas


Volumetry / Chromatography (Open Systems)

* fi i i

*i i in i out

i in i in i out i out

f fi i inf f

f * sHe

N

in CG k ink

n n n , i ...N

n n n dt

y n y n dt

n y npV n TV V V

n n n

0

0

Molar Balances 1

Total Amount (i)

Adsorptive's Amount (i)

Geometry, He-Volume

k in k in in

N

out CG k out k out k out outk

, y n n

n n n , y n n

4 PB-6A


Experimental setup for gravimetric-chromatographic measurements of multicomponent gas adsorption equilibria

V

T

p

Gas Chromatograph

Adsorption Chamber

Microbalance

CirculationPump

GasSupply

Thermostat

VacuumPump

AC

Gas Sample( yi, wi )f f

( yi, wi )* *

SorbentMaterial

Ballast

4 PB-7


Gravimetry / Chromatography (N 1)

* f a

Nf f f f f

i ii

sAC Hef

f fN

a * * f fi i i

sAC Hea *

i i

m m m

m M n y M n

p V Vn

R T Z p,T, y ...y

m w m w m

p V V: m w

R T

1

Total mass of gas supplied to system:

Sorptive mass / mole number:

Mass of component i=1...N adsorbed:

1

2

3

1 4

sAC Hef f f

i

p V VM w M

Z R T Z

a f sHe

fa s

HesAC He

m V

mm V AV V

Microbalance:

4

4

4 PB-7A


p

VacuumPump

OscillatingDisk

Filled with Adsorbens

Gas Supply

Laser and Diodes

PC

Mirror

SorptiveGas

Reflected Beam

Front View Top View

T

g

1

2

p

VacuumPump

OscillatingDisk

Filled with Adsorbens

Gas Supply

Laser and Diodes

PC

Mirror

SorptiveGas

Reflected Beam

Front View Top View

T

g

1

2

Experimental Setup for oscillometric measurements of gas adsorption equilibriausing a rotational pendulum.

Rotational pendulum for measurements of gasadsorption equilibria by observing slow dampedoscillations. Height of instrument: 1.5 m.


220 0

s 2EE

1m 1m 1

220 02

EEs 0 0

* *

1 11m

m 1

sIdeal Pendulum m ,m * sPhysical Pendulum m ,m ,m

* * *, ... empty pendulum m , vacuum

* s0 0, ... pendulum and adsorbent m ,m , vacuum

* sE E, ... pendulum, adsorbent, adsorbate m ,m ,m , gas

Oscillometric Measurements of Gas Adsorption Equilibria. Theory

4 PB-8A


Rotational pendulum and ring slit filled with polycarbonate pellets

4 PB-9


Swelling and sorption isotherm of polycarbonate / CO2 at 293 K

p [MPa]0 1 2 3 4 5 6 7

Vas

/ (m

a +ms )

[cm

3 /g]

0.80

0.85

0.90

0.95

1.00

1.05

m

g/g]

ma [m

g/g]

-50

0

50

100

150

200

250 Vas / (ma+ms)grav

osc

ma

4 PB-10


Schematic diagram of a sensorgas calorimeter (SGC)

Sensor gas calorimeter (SGC) forsimultaneous measurements of adsorption isotherms and enthalpies. © IFT, University of Siegen, 2003.

Air Thermostat

4 PB -11


Calibration experiments in the SGC 0.5J to 5JSensor gas N2 (1.6bar), T=298K, =10s

Ohm’s heat release (red lines) Pressure signal (blue lines)

0

20

40

60

80

100

120

0 100 200 300 400 500 600 700 800Time [s]

Diff

eren

ce P

ress

ure

[Pa]

0

50

100

150

200

250

300

350

400

450

500

Ele

ctri

cal

Pow

er [

mW

]

4 PB-12


0

20

40

60

80

100

120

0 200 400 600 800Timescale for Difference Pressure Axis [s]

Diff

eren

ce P

ress

ure

p(t)

[Pa]

0

50

100

150

200

250

300

350

400

450

5000 20 40 60 80 100

Timescale for Electrical Power Axis [s]

Ele

ctric

al P

ower

[m

W]

Difference PressureElectrical Power

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6

Ohm's Heat Q [J]

Red

uced

Pea

kare

a A

* [k

Pa

s]

2

0 525 6 211

0 9993

kPasA A* . kPas . QJ

R .

CorrelationPeak Area (A / Pas)Qhm’s heat (Q / J)

Calibration experiments of the SGC.Ohm’s heat : Q= (0.5, 1.0 ... 5.0)JSensor gas: N2, p*=0.15MPa, T*=298K

4 PB-12A


Differential and integral heat of adsorption for activated carbon AC BAX 1500 / n-butane (C4H10) at 298K

0 1 2 3 4 5 60

10

20

30

40

50

60

70

80

90

100

Heat of Condensation for n-butane (20,95 kJ/mol)

Mesured differential heat of adsorption Differenciated from integral heat of adsorption

Diff

eren

tial h

eat o

f ads

orpt

ion

[kJ/

mol

e]

n-butane ads. [mmole/g]

0

50

100

150

200

250

300

350

400

Measurend integral heat of adsorption Interpolated integral heat of adsorption

Inte

gral

hea

t of a

dsor

ptio

n [J

/g]

4 PB-13


Vacuum Pump

Gas Supply

p*

T

p

AdsorptionChamber

Gas Circulation Pump

T*

Storage Vessel

V*

Capacitor

Gas Chromatograph

mS

ImpedanceAnalyzer

IA

Sorbent

Heasfas**

MG VV,)T,p(VVmmM,V

MGDE m)T,p(DE

4 PB-14

Experimental setup for volumetric-dielectric measurements


f/ kHz2000 4000 6000 8000 10000 12000 1400

C/ F

5.1e-12

5.2e-12

5.3e-12

5.4e-12

5.5e-12

5.6e-12 Vakuum 0.01 MPa0.1961 MPa0.9916 MPa1.5001 MPa1.9924 MPa

Impedance spectra of CO2 on zeolite (DAY), T=298K

4 PB-15


Cole-Cole-Plot for system H2S / MS 13X, T=298K

Re 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Im

0.0

0.2

0.4

0.6

Vacuum0.01 MPa0.03 MPa0.1 MPa0.2 MPa0.4 MPa

4 PB-16


Cole-Cole-Plot for system CO / MS 13X, T=298K

Re 2.5 3.0 3.5 4.0 4.5

Im

0.0

0.2

0.4

0.6

Vacuum0.6 MPa1.9 MPa

12 MPa3.9 MPa

4 PB-17


Uptake curves of H2S on MS 13X, T=298K

4 PB-18

Time [h]0.0 0.2 0.4 0.6 0.8 1.0

Rel

ativ

e up

take

0

1

2

3

4

5

6Impedance spectroscopyGravimetry


Gibbs excess amount of adsorbed (nGE) [mmol/g]0 1 2 3 4 5

Cap

acita

nce

(C

) [p

F]

0.0

0.5

1.0

1.5

2.0

2.5

N2 / Pellets AC-20

CO / Pellets AC-20T = 298 K, = 4 MHz

CH4 / Pellets AC-20

a

Change of the dielectric capacity (C) of AC-20 pellets upon adsorption of gases (N2, CH4, CO) at 298 K, = 4MHz. Gas pressures (p 4MPa).

4 PB-19


64.0

64.1

64.2

64.3

64.4

64.5

64.6

64.7

64.8

64.9

65.0

360 380 400 420 440 460 480Time [s]

Cap

acita

nce

[pF]

25

50

75

100

125

Pre

ssur

e [k

Pa]

Zeolite: MS Na13XFrequency: 10 MHzCycle Time: 30 s

Capacitance

Pressure

Combined manometric (p) and dielectric (r) measurements of ad- and desorption of N2 on MSNa13X (UOP) at 293K.

4 PB-20


Gas Mixture SorptionHybrid Measurement Methods

Method Material Physics V G O SP CH D C Volumetry (V) Extensivity ++ + 0 ++ ++ 0

Gravimetry (G) Gravity 2 + 0 + + 0

Oscillometry (O) Inertia 1, V 1, V 0 0 0 0

Spectroscopy (SP) Electric Changes 1 1

Chromatography (CH) Molecules N N (N)

Densimetry (D) Extensivity 2 2 1, V

Calorimetry (C) Thermal Inertia 1 1 1

4 PB-21


Experimental Setup for volumetric-gravimetric measurements of binary coadsorption equilibria (M1M2)

4 PB-22


*i

sf 0i is i 1,2mm m 1 m

m

Mass balances

f fas 1 2

1 2 * fm mm m VV V

Micro-balance equation

f f1 2

1 2

* fm mM M

p V V

ZR T

Adsorptive’s equation of state

sf f f as0

1 2 1 2 smm , m , m , m ... V V 1 Vm

Volumetric-Gravimetric Measurements of Binary Coadsorption Equilibria (Theory)

1 2M M

4 PB-23


Schematic diagram of a volumetric-gravimetric-chromatographic installation with magnetic suspension balance for coadsorption measurements (N 1)

4 PB-24


to balance connection

coupling housingthermostat

pressure measurement

measuring fluid

measuring cell

thermostat

temperature measurement

measuring fluid

measuring fluid

sample (adsorbent)

electromagnet

suspension magnet

measuring load decoupling

Magnet suspension balance for sorption measurements (Rubotherm, Bochum, Germany)

4 PB-25

University of Siegen Institute of Fluid- & ThermodynamicsJürgen U. KELLER 06 4 PB-26

Magnetic Suspension Balance for Simultaneous Sorption and Density Measurements (Rubotherm, Bochum, Germany)


Coadsorption equilibria of methane/nitrogen gas mixtures on activated carbon (Norit R1). Data correlation: 2 sites LAI.

4 PB-27


Installation for Densimetric-Gravimetric Measurements (DGMs) of Binary Coadsorption Equilibria of Premixed Gases (y1, y2)* *

4 PB-28


Mass balances

Total gas mass supplied

Sorptive gas masses

a * fi i im m m i 1,2 (1)

(2)

(2A)

(3)

(4)

(5)

(6)

* * * a a f f1 2 1 2 1 2m m m m m m m

* f *m V * * *i im w m

* asf f1 2

1 2 i

p V Vm mM M R T Z p,T, w

a * f * si i 1iGE i He

i i 1 i

M p Mm m V VM M R T Z p,T, w

as sHeV V(1, 2A, 3, 4)

Densimetric-Gravimetric Measurements (DGMs) of Coadsorption Equilibria (Theory)

f f f * as1 2m m V V

4 PB-29

University of Siegen Institute of Fluid- & ThermodynamicsJürgen U. KELLER 06First Instrument MSB (3)

First performance of DGMs using a MSB (3)on 1998-02-11 in Lab PB-A0126 of IFT/USI

4 PB-30


Diagram CO2/CH4

2 4

i i

2 4 CO CH

i i 2 4

Coadsorption equilibria of CO / CH at T 293K, y 20.4%mol, y 79.6%mol

on AC D47 /3. Correlation by GAI : n n (bp) 1 (bp) , i CO , CH

4 PB-31


Installation for Densimetric-Volumetric Measurements (DVMs) of Binary Coadsorption Equilibria of Premixed Gases y1, y2.* *

4 PB-32


Mass balances a * fi i im m m

EOS

i 1,2 (1)

(2)

(3)

(4)

(5)

(6)

* ** i SVi i*

y p Vm M

R T Z * *

iZ Z p ,T, y

Sorptive gas massesf f1 2(m ,m )

f f f * as1 2m m V V

fi

i f f1 2

mw

m m

i 1,2

as sHeV V

a * f * si i 1iGE i He

i i 1 i

M p Mm m V VM M R T Z p,T, w

(1 – 4)

Densimetric-Volumetric Measurements (DGMs) of Coadsorption Equilibria (Theory).

4 PB-33

* asf f1 2

1 2 i

p V Vm mM M R T Z p,T, w


Photo automated MSB

Automated MSB (2) (Rubotherm AG, Bochum) for Densimetric-Volumetric Measurements (DVMs) of binary coadsorption equilibria

4 PB-34


Comparison of experimental pros and cons of densimetric-gravimetricmeasurements (DGMs) and densimetric-volumetric measurements (DVMs)of binary gas adsorption equilibria without analyzing the sorptive phase.

4 PB-35


Vacuum Pump

Gas supply

p*

RotationalPendulum

T

p

AdsorptionChamber


T*

Storage Vessel

V*V

Gaschromatograph

Experimental Setup for oscillometric-volumetric measurementsof gas sorption equilibria in swelling materials.

4 PB-36


Vacuum Pump

T

Gas supply

Microbalance

Sorption Chamber

T

ppRotationalPendulum

SorptionChamber


mPolymerSorbent

Experimental Setup for oscillometric-gravimetric measurementsof gas sorption equilibria in swelling materials.

4 PB-37


Volumetric-gravimetric-oscillometric method (N=2).Co(ad)sorption measurements in swelling sorbent materials (polymers) without using a gas chromatograph.

4 PB-38


p [MPa]0 1 2 3 4 5 6 7

V [c

m3 /g

]

0.80

0.85

0.90

0.95

1.00

1.05

1.10

V 308 KV 318 KFit

V = 0.0035 p + 0.86

V = 0.0022 p + 0.86

p [MPa]0 1 2 3 4 5 6 7

m [m

g/g]

0

20

40

60

80

100

120

140

160

m 308 Km 318 KDual Modus

Swelling isotherms of polycarbonate/CO2at T = 308 K and T = 318 K.

4 PB-39

Sorption isotherms of polycarbonate/CO2at T = 308 K and T = 318 K.


Measurement Methods for Gas Adsorption Equilibria

Pure Gas MethodVolumetry/Manometry

GravimetryOscillometryDielectric Permittivity

Gas Mixtures (N=2)Volumetric-Densimetric M.(2-sites Magnetic Balance)

Gas Mixtures (N>2)Volumetric/Gas Phase Analysis

PurposeCharacterization of porous solids

Equilibria, Kinetics, Gas Density, Process Cont.Swelling MaterialIndustrial Process Control

Equilibria, Process Control

Process Design

Ref:J.U. Keller, R. Staudt, Gas Adsorption Equilibria, Springer, New York, 2004.

4 PB-40

j.u. keller , n. iossifova , w. zimmermann , f. dreisbach ... · pdf fileadsorption equilibria...

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