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

Transcription

1 4 PB-1 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-578 Siegen, Germany 2) Rubotherm Präzisionsmesstechnik GmbH Universitätsstr. 142, Bochum, Germany 3) Center of Non-Classical Chemistry, University of Leipzig Permoserstr 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

2 4 PB-2 Adsorptive 1 Adsorption (exothermic) Adsorptive 2 Desorption (endothermic) Adsorbate Adsorbent Adsorption

3 4 PB-3 1 Sample / Sorbent 2 Dewar vessel (N 2, 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) Gas Flow Porosimeter (He, N 2, BET, 77 K)

4 4 PB -4 Experimental setup for volumetric-chromatographic measurements of multi-component gas adsorption equilibria

5 4 PB-4A Mass balances Total mass (i) Adsorptive s mass (i) * f i i i m m m i 1...N * * f * * * i i 1 N SV m w T,p,w...w V f f S i i SV AC m V V V (1) (2) (3) f i i i (1 3) : m V S (4) * i i i VSV ivac f f i i N i w T,p,w,...w, w : GC S S V V He m i... Gibbs excess mass Volumetry / Chromatography (Closed Systems)

6 4 PB-5 Adsorption equilibria of a CH4-CO2-N2 gas mixture on activated carbon ACR1. Data correlation:2-sites LAI

7 4 PB -6 Gas Solid Adsorption Equilibria : Volumetric Chromatographic Analysis (N1) Sorbent Material Sorbate F L O W Sorptive Gas N 2 Ar CO 2 CH 4 R A T E S T F T Gas Chromatograph GC PC ia Impedance Analyzer Formulation Analysis

8 4 PB-6A Molar Balances n n n, i 1...N Total Amount (i) Adsorptive's Amount (i) Geometry, He-Volume * f i i i * i iin iout 0 n n n dt f i f Volumetry / Chromatography (Open Systems) 0 n y n iin f pv n T V V V f * s iin iin iout iout f N He in CG k in k N y n y n dt n n n, ykin n kin nin n n n, y n n out CG k out k out k out out k

9 4 PB-7 Circulation Pump Gas Supply * * ( y i, w i ) p Sorbent Material V AC Microbalance Adsorption Chamber Ballast Vacuum Pump T Thermostat Gas Sample Gas Chromatograph f ( y i, w f i ) Experimental setup for gravimetric-chromatographic measurements of multicomponent gas adsorption equilibria

10 4 PB-7A Total mass of gas supplied to system: Microbalance: * f a m m m 1 m V Sorptive mass / mole number: m M n y M n n N f f f f f i i i f pv Mass of component s AC He f f R T Z p,t, y 1...y N a * * f f i i i V m w m w m 2 s s pvac V a * He pvac VHe :mi wi M wi M RTZ RTZ Gravimetry / Chromatography (N 1) 14 3 i=1...n adsorbed: a f s He f f f 4 f a m s m V s He 4A V V AC He

11 Gas Supply p Oscillating Disk Filled with Adsorbens Sorptive Gas g T Laser and Diodes 1 2 Mirror Reflected Beam Vacuum Pump PC Front View Top View Rotational pendulum for measurements of gas adsorption equilibria by observing slow damped oscillations. Height of instrument: 1.5 m. Experimental Setup for oscillometric measurements of gas adsorption equilibria using a rotational pendulum.

12 4 PB-8A s Ideal Pendulum m,m * s Physical Pendulum m,m,m s 2 E E m m E E 1 m 1 s m * * 2 1 * * *,... empty pendulum m, vacuum 0 0 E * s,... pendulum and adsorbent m,m, vacuum E * s,... pendulum, adsorbent, adsorbate m,m,m, gas Oscillometric Measurements of Gas Adsorption Equilibria. Theory

13 4 PB-9 Rotational pendulum and ring slit filled with polycarbonate pellets

14 4 PB V as / (m a +m s ) grav 1.05 mg/g] m a [mg/g] osc m a V as / (m a +m s ) [cm 3 /g] p [MPa] Swelling and sorption isotherm of polycarbonate / CO 2 at 293 K

15 4 PB -11 Air Thermostat Schematic diagram of a sensor gas calorimeter (SGC) Sensor gas calorimeter (SGC) for simultaneous measurements of adsorption isotherms and enthalpies. IFT, University of Siegen, 2003.

16 4 PB-12 Difference Pressure [Pa] Time [s] Electrical Power [mw] Calibration experiments in the SGC 0.5J to 5J Sensor gas N 2 (1.6bar), T=298K, =10s Ohm s heat release (red lines) Pressure signal (blue lines)

17 4 PB-12A Difference Pressure p(t) [Pa] Timescale for Electrical Power Axis [s] Difference Pressure Electrical Power Timescale for Difference Pressure Axis [s] Calibration experiments of the SGC. Ohm s heat : Q= (0.5, )J Sensor gas: N 2, p*=0.15mpa, T*=298K 50 0 Electrical Power [mw] Reduced Peakarea A* [kpa s] kpas A A* kpas Q J R. Correlation Peak Area (A / Pas) Qhm s heat (Q / J) Ohm's Heat Q [J]

18 4 PB Differential heat of adsorption [kj/mole] Mesured differential heat of adsorption Differenciated from integral heat of adsorption Measurend integral heat of adsorption Interpolated integral heat of adsorption Heat of Condensation for n-butane (20,95 kj/mol) Integral heat of adsorption [J/g] n-butane ads. [mmole/g] Differential and integral heat of adsorption for activated carbon AC BAX 1500 / n-butane (C 4 H 10 ) at 298K

19 4 PB-14 Gas Supply Gas Circulation Pump Capacitor p p * T * Storage Vessel V * T Adsorption Chamber Sorbent m S Impedance Analyzer IA Gas Chromatograph Vacuum Pump V, M m MG m * DE (p,t) DE m MG * as f as V V (p,t), V VHe Experimental setup for volumetric-dielectric measurements

20 4 PB e e-12 Vakuum 0.01 MPa MPa MPa MPa MPa C/ F 5.4e e e e f/ khz Impedance spectra of CO 2 on zeolite (DAY), T=298K

21 4 PB Im 0.4 Vacuum 0.01 MPa MPa 0.1 MPa 0.2 MPa 0.4 MPa Re Cole-Cole-Plot for system H 2 S / MS 13X, T=298K

22 4 PB-17 Im MPa 3.9 MPa 1.9 MPa 0.6 MPa Vacuum Re Cole-Cole-Plot for system CO / MS 13X, T=298K

23 4 PB Impedance spectroscopy Gravimetry Relative uptake Time [h] Uptake curves of H 2 S on MS 13X, T=298K

24 4 PB Capacitance (C) [pf] N 2 / Pellets AC-20 CH 4 / Pellets AC-20 CO / Pellets AC-20 T = 298 K, = 4 MHz Gibbs excess amount of adsorbed (n GE ) [mmol/g] a Change of the dielectric capacity (C) of AC-20 pellets upon adsorption of gases (N 2, CH 4, CO) at 298 K, = 4MHz. Gas pressures (p 4MPa).

25 4 PB Pressure 125 Capacitance [pf] Capacitance Zeolite: MS Na13X Frequency: 10 MHz Cycle Time: 30 s Pressure [kpa] Time [s] Combined manometric (p) and dielectric ( r ) measurements of ad- and desorption of N 2 on MSNa13X (UOP) at 293K.

26 4 PB-21 Gas Mixture Sorption Hybrid Measurement Methods Method Material Physics V G O SP CH D C Volumetry (V) Extensivity Gravimetry (G) Gravity Oscillometry (O) Inertia 1, V 1, V 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

27 4 PB-22 Experimental Setup for volumetric-gravimetric measurements of binary coadsorption equilibria (M 1 M 2 )

28 4 PB-23 Mass balances Micro-balance equation f m m 0 i 1 m s m * s m i i i 1,2 f f as m1 m2 1 2 * f m m V V V Adsorptive s equation of state m M f f 1 m2 M 1 2 p V * f ZRT V M M 1 2 s f f f m 0 as s m, m, m, m... V V 1 V m Volumetric-Gravimetric Measurements of Binary Coadsorption Equilibria (Theory)

29 4 PB-24 Schematic diagram of a volumetric-gravimetric-chromatographic installation with magnetic suspension balance for coadsorption measurements (N 1)

30 4 PB-25 to balance connection electromagnet suspension magnet coupling housing thermostat measuring load decoupling pressure measurement measuring fluid measuring fluid sample (adsorbent) measuring cell thermostat measuring fluid temperature measurement Magnet suspension balance for sorption measurements (Rubotherm, Bochum, Germany)

31 4 PB-26 Magnetic Suspension Balance for Simultaneous Sorption and Density Measurements (Rubotherm, Bochum, Germany)

32 4 PB-27 Coadsorption equilibria of methane/nitrogen gas mixtures on activated carbon (Norit R1). Data correlation: 2 sites LAI.

33 4 PB-28 Installation for Densimetric-Gravimetric Measurements (DGMs) of Binary Coadsorption Equilibria of Premixed Gases (y* 1, y* 2 )

34 4 PB-29 Mass balances Total gas mass supplied Sorptive gas masses a * f i i i m m m i 1,2 (1) * * * a a f f m m m m m m m m m * f * * * * i wim V f f f * as 1 2 m m V V * as f f m p V V 1 m 2 M M RTZ p,t,w 1 2 i (2) (2A) (3) (4) (1, 2A, 3, 4) as s V V He (5) M pm m m V V a * i f i 1 * s ige i He Mi Mi1 RTZ p,t,wi Densimetric-Gravimetric Measurements (DGMs) of Coadsorption Equilibria (Theory) (6)

35 First Instrument MSB 4 PB-30 (3) First performance of DGMs using a MSB (3) on in Lab PB-A0126 of IFT/USI

36 4 PB-31 Diagram CO2/CH4 Coadsorption equilibria of CO / CH at T 293K, y 20.4%mol, y 79.6%mol 2 4 CO CH 2 4 i i 2 4 on AC D47 /3. Correlation by GAI : n n (bp) i 1 (bp) i, i CO, CH

37 4 PB-32 Installation for Densimetric-Volumetric Measurements (DVMs) of Binary Coadsorption Equilibria of Premixed Gases y* 1, y * 2.

38 Mass balances m m m EOS Sorptive gas masses f f (m,m ) 1 2 (1 4) m a * f i i i * * * yi p VSV i M * * * i Z Z p,t,y i RTZ f f f * as 1 2 m m V V 1 2 i f mi i f f m1 m2 as s w V V He i 1,2 (1) i 1,2 M pm m m V V a * i f i 1 * s ige i He Mi Mi1 RTZ p,t,wi Densimetric-Volumetric Measurements (DGMs) of Coadsorption Equilibria (Theory). * as f f m p V V 1 m 2 M M RTZ p,t,w 4 PB-33 (2) (3) (4) (5) (6)

39 4 PB-34 Photo automated MSB Automated MSB (2) (Rubotherm AG, Bochum) for Densimetric-Volumetric Measurements (DVMs) of binary coadsorption equilibria

40 4 PB-35 Comparison of experimental pros and cons of densimetric-gravimetric measurements (DGMs) and densimetric-volumetric measurements (DVMs) of binary gas adsorption equilibria without analyzing the sorptive phase.

41 4 PB-36 Gas supply Gas Circulation Pump Rotational Pendulum p p * Storage Vessel T T * V * Adsorption Chamber V Gaschromatograph Vacuum Pump Experimental Setup for oscillometric-volumetric measurements of gas sorption equilibria in swelling materials.

42 4 PB-37 Gas supply Rotational Pendulum p p Microbalance T m Polymer Sorbent T Sorption Chamber Sorption Chamber Vacuum Pump Gas Circulation Pump Experimental Setup for oscillometric-gravimetric measurements of gas sorption equilibria in swelling materials.

43 4 PB-38 Volumetric-gravimetric-oscillometric method (N=2). Co(ad)sorption measurements in swelling sorbent materials (polymers) without using a gas chromatograph.

44 4 PB V = p m [mg/g] V [cm 3 /g] V = p p [MPa] V 308 K V 318 K Fit m 308 K m 318 K Dual Modus Swelling isotherms of polycarbonate/co 2 at T = 308 K and T = 318 K p [MPa] Sorption isotherms of polycarbonate/co 2 at T = 308 K and T = 318 K.

45 4 PB-40 Measurement Methods for Gas Adsorption Equilibria Pure Gas Method Volumetry/Manometry Gravimetry Oscillometry Dielectric Permittivity Gas Mixtures (N=2) Volumetric-Densimetric M. (2-sites Magnetic Balance) Gas Mixtures (N>2) Volumetric/Gas Phase Analysis Purpose Characterization of porous solids Equilibria, Kinetics, Gas Density, Process Cont. Swelling Material Industrial Process Control Equilibria, Process Control Process Design Ref:J.U. Keller, R. Staudt, Gas Adsorption Equilibria, Springer, New York, 2004.