Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003
CatalyCatalytictic DistillationDistillation
Kai Sundmacher1,2
1 Max-Planck-Institute for Dynamics of Complex Technical Systems Sandtorstraße 1, 39106 Magdeburg, Germany
2 Otto-von-Guericke-University Magdeburg, Process Systems Engineering Universitätsplatz 2, 39106 Magdeburg, Germany
[email protected] Catalytic Distillation (CD) - Outline
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Experimental Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Integration of Unit Operations in Multifunctional Reactors
Raw Materials Main Products Recycle
Physical Chemical/ Separation Separation Unit Biological Units for Units for Operations Units Reactants By-Products
Multifunctional Multifunctional Reactors (e.g. Reactors (e.g. Fuel Cells) Reactive Mill) By-Products Multifunctional Reactors (Reactive Distillation / Absorption / Extraction / Adsorption Column) Possible Benefits from Multifunctional Reactor Concepts
Synergetic interactions of chemical and physical unit operations may lead to:
á increase of productivity from process intensification á increase of selectivity of reactions and/or separations á reduction of by-products and waste materials á more efficient (in situ) use of energy á inherent safety á improved environmental compatibility (e.g. by avoidance of hazardous solvents etc.). Reactor-Separator System for Isomerization A1 Û A2
Reaction Kinetics: Vapour-Liquid-Equil.: Design Variables: V k æ 1 x ö a x - Damköhler Number Da º R n 2 y = 2 F r = k x1 ç1- ÷ 2 - Number of Stages N K x 1+ (a -1)x2 here è 1 ø D - Product Quality x2 = X
Operational Variables: L D, x D 2 - Reflux Ratio R º L / D CSTR A2 - Recycle Ratio j º B / F Distillation F, x F = 1 1 Column Thermodynamic Parameters: VR - equilibrium constant K A 1 VR N - relative volatility a º K2 / K1 A A 1 2 Kinetic Parameters: - reaction order n B - rate constant k
Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation. Reactor-Separator System for Isomerization A1 Û A2
Design for Reaction Order n = 1 CSTR + Column on Top
25 X = 0.99
min j = 2 R ® ¥ D N L D, x2 K = 2, a = 1.5 =
N A j = 5 n = 1 2 20 N Distillation j = 10 j = ¥ Column
15 F CSTR A j = ¥ 1 V Minimum Number of Stages, R 10 0 2 4 6 8 10 Damköhler Number, Da Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation Damköhler Number in CD Processes
k ×V Da º R Damköhler number F for first order reactions
Boiling temperature
k = e catcSiteskapp (Tb ) Tb = Tb ( p, x)
apparent + rate control catalyst concentration rate via pressure ! holdup of active sites constant temperature on catalyst + T is not a dynamic variable ! Reactive Distillation Column for Isomerization A1 Û A2
Reactive Distillation Column Influence of Reaction / Separation
Daopt (N = 20) = 0.2 x 20 = 4 1,0 N = X = 92.5 % 100 50 20 Reactive L D 0,8 10 5 Azeotrope 2 R = L / D 1 X 0,6 Xeq = 66.6 % N Reaction / Separation: (CSTR) Da V k A e c = R µ c cat sites N F N NTSM 0,4 F Conversion,
Total 0,2 a = 1.5 K = 2, n = 1 Reboiler R = 10
0,0 0,001 0,01 0,1 1 10 100 Da / N Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation. Design of Hybrid CD Column for Isomerization A1 Û A2
Hybrid Column with Influence of Catalyst Distribution Catalytic Stages 1,00 100 20 10 0,95 R = L / D 5 Base L D Case 20 0,90 19
X 2 18 . . . 0,85 . R = 1 . N = 20 . Ncat . Conversion, 0,80 3 2 a = 1.5 F 1 K = 2, n = 1 0,75 N = 20 Total Da = 4 Reboiler 0,70 2 4 6 8 10 12 14 16 18 20 Number of Catalytic Stages, Ncat
Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation. Reactive Batch Distillation: MeOH + IA Û TAME
Vapour phase: Vapour Flow V
Composition yi Heating policy: V / V0 = H / H0 FCR
MeOHV IAV TAMEV
H+ Liquid phase: MeOHL + IAL TAMEL LCR Holdup H
Composition xi
Qreb
Catalyst: Acidic Ion Exchange Resin (Vcat, cH+)
Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005. Reactive Batch Distillation: Model Equations
Mass Balances
d xi * = ( xi - yi (x,T)) + Da ×(n i - xi n) × r (x,T) dt 1442443 14243 123 Separation by Influence of Reaction Distillation Stoichiometry Kinetics
Damköhler Number Boiling Temperature k (T )×c ×V Da º + ref sites cat T = T(x, p) V& o
Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005. Catalytic Batch Distillation for TAME-Synthesis: No Reaction (Da = 0)
MeOH 2 stable nodes 1 unstable node (azeotrope) 1 saddle point (azeotrope) 1 separatrix MeOH of p = 10 bar Fraction Mole
TAME IA Mole Fraction IA
Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005. Catalytic Batch Distillation for TAME-Synthesis: Slow Reaction (Da = 10-4)
MeOH 3 stable nodes 0 unstable nodes 2 saddle points 2 separaticds chemical equilibrium line MeOH
of p = 10 bar Fraction Molenbruch Methanol Mole IA TAME MolenbruchMole Fraction Isoamylenof IA
Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005. Catalytic Batch Distillation for TAME-Synthesis: Fast Reaction (Da = 10-3)
MeOH 2 stable nodes 0 unstable nodes 1 saddle point 1 separatrix
MeOH chemical equilibrium line of
p = 10 bar Fraction Mole TAME IA Mole Fraction of IA
Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005. Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) TAME
MoleMolenbruchFraction Methanolof MeOH Catalytic BatchDistillationfor MeOH Mole Reaction Molenbruch Isoamylen Fraction in Equilibrium Chem. Eng. of IA chemical equilibrium 1 1 0 2 stabile Sci separatix saddle unstable nodes . TAME 52 , 993 (Da >1) p - 1005. = 10bar nodes point - Synthesis: IA line Studies of Side Reactions: Influence of Stage Damköhler Number
2 2 Main Rxn 2 B Û A + C xB - xA xC / Keq 0.1 x r* = r* = C Side Rxn 2 C ® 2 D main 2 side 2 (1 + 5 xC ) (1 + 5 xC ) aAC = 10 Keq = 0.25 1,0 aBC = 3 R = 3.8 Selectivity, S aDC = 13 S = 5.3 0,8
Variation A + D 0,6 of Da on
stage 9 stages 0,4 B 20 stages Conversion, X Feed at 0,2 stage 20 9 stages 0,0 0,01 0,1 1 N = 38 C Stage Damköhler Number, Da Studies of Side Reactions: Influence of Catalyst Position
Main Rxn 2 B Û A + C 2 2 * xB - xA xC / Keq * 0.1 xC Side Rxn 2 C ® 2 D rmain = 2 rside = 2 (1 + 5 xC ) (1 + 5 xC ) aAC = 10 Keq = 0.25 Selectivity, S 1,0 aBC = 3 R = 3.8 aDC = 13 S = 5.3 0,8
Da = 0.8 A + D 0,6 Conversion, X on stage
Changing Position of Catalyst 0,4 B 5 stages Feed at 0,2 stage 20 0,0 5 10 15 20 25 30 N = 38 C Position of Catalyst Section Studies of Side Reactions: Influence of Catalyst Position (Da = 0.2, Reactive Stages = 5)
A + D A + D
* 2 B rmain xB - xA xC / Keq B * ~ 2 rside xC
C C D D 0 0 A A 5 5
10 B 10 B 15 15
20 20 Stage Stage 25 25
30 30 C C 35 35
40 40 0,0 0,2 0,4 0,6 0,8 1,0 0,0 0,2 0,4 0,6 0,8 1,0 x x i i Mapping of Reactor-Separator Systems for
Esterification: Alcohol + Acid Û Ester + H2O
Fast r Rate, Reaction
Slow
Low Medium High see e.g.: Schoenmakers (1997) Relative Volatility, aH2O/Ester RD System based on Pre- and Side Reactors
Ether Production Flow Scheme (Neste Oy) Advantages Pre-Reactors Side-Reactors l easy catalyst replacement
l easy control of reactant-ratio
l independent of specific catalyst packing
l distillation column hydraulics and mass transfer not affected by catalyst structure
CxHy l high Da/N-ratio achievable MeOH
MeOH
see e.g.: Aittamaa, J., Eilos, I., Jakkula, J., Lindqvist, P., US 5 637 777 (1997) Simple Guideline for CD Reactor Selection p Slow reactions: Da << 1 p Fast reactions: Da ³ 1
+ reaction kinetics is limiting + mass transfer is limiting + high residence time + low residence time sufficient + hom. catalysis: high liquid holdup + hom. catalysis: low liquid holdup + het. catalysis: high catalyst holdup + het. catalysis: low catalyst holdup p Solution p Solution
+ tray column (bubble caps) + packed column + packed column with random packing + tray column with low holdup + column with external side reactors
increase p Catalytic Distillation (CD) - Outline
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Experimental Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Motives for Application of Reactive Distillation
Motives Examples
Overcoming Limitations Methanol + Acetic Acid Û Methyl Acetate + H2O of Chemical Equilibrium Methanol + Isobutene Û Methyl-tert.-butylether (MTBE)
Formaldehyde + 2 Methanol Û Methylal + H2O
Increase of Chlorohydrins ® Propylene Oxide + H2O ® Proplene Glycol Selectivity 2 Acetone ® Diacetone Alcohol ® Mesityl Oxide + H2O Reaction Problems Isobutane + 1-Butene ® Isooctane + 1-Butene ® C12H24
Use of Heat Propene + Benzene ® Cumene
of Reaction Ethylene Oxide + H2O ® Ethylene Glycol
Separation of m-Xylene / p-Xylene (Reactive Entrainer: Na-p-Xylene) Closely Boiling Mixtures Cyclohexene / Cyclohexane (Reactive Entrainer: Formic Acid) 1-Butene / Isobutene (Reactive Entrainer: Methanol / Water)
Breaking of Methyl Acetate / Water ; Methyl Acetate / Methanol
Problems Azeotropes (Entrainer: Acetic Acid) Separation
High Purity Hexamethylene Diamine / Water (in Nylon 6,6 process) Separation (Reactive Entrainer: Adipic Acid)
See e.g.: Sundmacher, K., Rihko, L., Hoffmann, U., Chem. Eng. Commun. 127 (1994) 151-167. Production of Methyl Acetate
Reaction: H+ Acetic Acid + Methanol ¨ MeAc + Water
Catalysts: H2SO4 / Acidic Ion Exchange Resin
Chemical Equilibrium Constant: Kx(25°C) = 5.2
Boiling Sequence at p = 0.1 MPa: hom. azeotrope MeAc/Methanol 53.8 °C hom. azeotrope MeAc/Water 56.7 °C Methylacetate (MeAc) 56.9 °C Methanol 64.6 °C Water 100.0 °C Acetic Acid 118.0 °C
L/L-phase splitting: in ternary system MeAc/Methanol/Water Production of Methyl Acetate (Conventional Process)
Acetic Acid Acetic Acid Methanol Methanol H2SO4 (Cat.) Methyl Acetate Reactor Extractive Distillation Distillation Distillation Distillation
Ethylene Glycol Water
Phase Sep. Distillation Distillation Distillation Azeotropic Distillation Extraction Water + Ethyl- H2SO4 acetate Water High Boilers Production of Methyl Acetate (CD Processes)
Homogeneously Catalyzed Reaction* Heterogeneously Catalyzed Reaction**
Methyl Methyl Acetic Acetate Acid Acetate Acetic Rectifying Impurities Acid H2SO4 Section (6 Stages) (Catalyst) Reactive Section Return from (13 Stages, Impurity removal Ion Exchange Columns Methanol Resin Packing)
Methanol Stripping Section (6 Stages)
Water +
H2SO4 Water
* Agreda, V.H.; Partin, L.R., US Patent No. 4,435,595 (1984, Eastman-Kodak-Process) **Bessling, B.; Löning, J.-M.; Ohligschläger, A.; Schembecker, G.; Sundmacher, K., Chem. Eng. Technol. 21 (1998) 393-400. CD Application for Highly Exothermic Reactions Example: Cumene Production
Reaction Scheme Vent (C3) CH3-CH-CH3
CH2=CH-CH3 + Cumene Propylene Benzene Cumene Reactive Zone CH -CH-CH CH -CH-CH 3 3 3 3 Propylene Distillation
+ CH2=CH-CH3 Stripping Cumene Propylene Zone CH3-CH-CH3 DIPB
CH3-CH-CH3 CH3-CH-CH3
+ 2 Benzene DIBP
l p = 3 - 10 bar, T » 250 °C CH -CH-CH max 3 3 l Solid acid catalyst
DIPB Benzene Cumene l Reaction heat: (-DRH) » 113 kJ/mol l By-product formation favored at higher T
Shoemaker, J.D., Jones, E.M., Hydrocarbon Processing (1987) 57-58. RD Application for High Purity Separation, Example: C4-Separation (Hüls-UOP*)
Feed Fixed Bed Reactive Methanol Methanol/ Wash Tubular Distillation Extraction Water Reactor Column Distillation
Methanol Recycle Methanol
Nonreacted C4 Nonreacted C4 + Methanol (Raffinate II)
Water Water
Kata- Max
C4 (IB+Inerts) (Raffinate I) XIC4 » 90 % Water + X » Impurities IC4 99.9 % p = 5...10 bar MTBE see e.g.: anonymus, Hydrocarbon Processing 73 (1992) 104-110. * approx. 32 % market share Catalytic Distillation (CD) - Outline
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Experimental Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Catalytic Packings: Aspects of Selection
Reaction Rate
(Catalyst Holdup: ecat)
Catalytic Packing
Hydraulic Capacity Mass Transfer (Void Fraction: 1 - ecat) Efficiency (Number of Theoretical Stages: NTSM) Catalytic Bales (CD Tech)
Distillate Fiber Glass Cloth Wire
Feed
Bottoms Catalyst Beads
see e.g. Smith, L. A. et al., EP 466954 A1 (1990) Catalytic Distillation Trays
CR & L IFP SNAMPROGETTI
DD D R D D
D R D D D D R R R
R RR Lionel, A. et al., US 5368691 (1994)
Domenico, S. et al., US 5493059 (1996)
Jones Jr., Edward M., US 5130102 (1992) Three-Levels-of-Porosity Concept
Three Pore Levels: I. m-Pores inside catalytic particles II. mm-Pores between catalytic particles III. cm-Pores between the catalytic pockets
Separation zone
Reaction zone
see e.g.: Krishna, R., Sie, S.T., Chem. Eng. Sci 49 (1994) 4029-4065. Structured Catalytic Packings
KATAPAK-S (Sulzer Chemtech) MULTIPAK (Julius Montz)
Stringaro, J.P., EP 631813 A1 (1993) Gorak, A., Kreul., L. U., DE 197 01 045 A1 (1998) Hydrodynamic Behaviour of Structured Catalytic Packing
§ Gas flow through open channels (1)
§ Liquid flow through open channels and catalyst bags (2)
§ Liquid holdup in open channels increases resistance for gas flow
§ Load point determines max. liquid flow through catalyst bags
Adopted from: Hoffmann, A., Gorak, A. (2000) Treffen der GVC-Fachausschüsse in Wernigerode. Internally Finned Monoliths (IFM)
S/V
e
Lebens, P. J. M., Kapteijn, F., Sie, T.N., Moulijn, J.A., Chem. Eng. Sci. 54 (1997) 1359-1365. Catalytic Distillation Process for Fuel Ether Production (TU Clausthal)
Catalytically Active Supported Ion Rings (8x8 mm) Exchange Resin
Catalytic Packing
Feed
Inert Packing Gel Particles (1-2 mm) with Macroporous - + R-SO3 H as Acidic Functional Support + Groups, cL = 1,0 eq(H )/l (Pores: 3 mm)
see e.g.: Hoffmann, U. et al., DP 4234779.3 (1992); Sundmacher, K. and Hoffmann, U. (1996) Chem. Eng. Sci. 51, 2359-2368. Gel Particles in Catalytic Rings (TU Clausthal)
Porous Glass Support
Gel Particle
10 mm
see e.g.: Sundmacher, K.; Künne, H.; Kunz, U. (1998) Chem.-Ing.-Tech. 70, 267-271. Some Properties of Catalytic Packings
3 3 * * * Void Fraction [m /mcol ] 0.49 0.75 0.75 0.75
3 3 * * * Catalyst [mcat /mcol ] 0.51 0.20 0.20 0.25 Loading
2 3 * * * Catalyst [mcat /mcat ] 1129 4000 4000 4000 Surface-to- Volume Ratio
2 3 * * * Packing [mcat /mcol ] 576 800 800 1000 Surface-to- Volume Ratio * See: Lebens, P. J. M., Kapteijn, F., Sie, T.N., Moulijn, J.A., Chem. Eng. Sci. 54 (1997) 1359-1365. Catalytic Distillation (CD) - Outline
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Experimental Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Modelling, Simulation and Experimental Validation: Etherification Reaction Systems
MTBE-System: Parallel Reactions TAME-System: Reaction Triangle
CH =C(CH )-CH -CH + Methanol C(CH ) -O-CH 2 3 2 3 3 3 3 2-methyl-1-butene (2M1B) + Methanol (MeOH) (MTBE) (MeOH) rTAME1 rMTBE (CH ) C=CH CH -CH -C(CH ) -O-CH 3 2 2 rISO 3 2 3 2 3 Isobutene (IB) (TAME) rDIB rTAME2 + (CH3)2C=CH2 + Methanol Isobutene (IB) C H (MeOH) 8 16 CH3-C(CH3)=CH-CH3 Diisobutene (DIB) 2-methyl-2-butene (2M2B)
Reactive Olefin: IB = Isobutene Reactive Olefins: IA = Isoamylenes Side Product: DIB = Diisobutenes (2M1B + 2M2B) Inert Solvent: 1-Butene (1B) Inert Solvent: n-Pentane (nP)
Heterogeneous Catalysts: Macroporous Sulfonic Acid Ion Exchange Resins Sorption Behaviour at Catalytically Active Gel Phase of Acidic Ion Exchange Resin
Nonideal Mixing Behaviour of MeOH/IB in the Liquid Phase Liquid Gel Phase 1 Phase i
a ai q , i
KS,i
Activity Methanol
Isobutene Generalized Langmuir Sorption Isotherm*:
Liquid Phase Method: UNIQUAC KS ,i ai Temperature: 60 °C q i = 0 N 0 1 1+ K a Mole Fraction Methanol, xi å S , j j j=1
* see e.g.: Jaroniec, M., Patrykiejew, A., Borowko, M., Prog. Surf. Mem. Sci. 14 (1981) 1-68. Microkinetics of Liquid Phase Etherification at Acid Ion Exchange Resins l General Rate Expression for l Experimental Data from CSTR Etherification of iso-Olefins Liquid Phase Reaction - reaction of sorbed species is T = 60 °C )] Cat.: A 15 / SPC 118
rate retermining step eq dp = 42 mm / 200-315 mm - methanol sorption in the catalytic gel phase is highly
selective: KS,MeOH » KS,i / [mmol/(s· 1 - ) MTBE æ a 1 a ö O Iso-Olefin Ether c r = k(T ) ç - ÷ / ç 2 ÷ IO è aMeOH Ka (T ) aMeOH ø c MTBE Formation Rate, x (
k (T = 60°C) =15.5 mmol/(s×eq) r TAME MTBE MTBE Ea,MTBE = 92.4 kJ/mol
kTAME(T = 60°C) = 2.58 mmol/(s×eq) TAME Mole Fraction Methanol, xMeOH Ea,TAME = 89.5 kJ/mol
For MTBE-kinetics see: Rehfinger, A., Hoffmann, U. (1990) Chem. Eng. Sci. 45, 1605-1617 For TAME-kinetics see: Oost, C., Hoffmann, U.. (1996) Chem. Eng. Sci. 51, 329-340 Modeling of Catalytic Distillation Column
p Vj Lj-1 V L xi,j xi,j-1 h V h L PSEUDOHOMOGENEOUS MODEL j j-1 + V/L mass transfer model R T V T L j j-1 + reaction microkinetics j - 1 j U Qj V L HETEROGENEOUS MODEL Fm j + 1 S („Fully rate-based“) a,b + V/L mass transfer model + reaction microkinetics + intraparticle mass transfer Vj+1 Lj V L (Maxwell-Stefan-eqs.) xi,j+1 xi,j V L hj+1 hj V L SPECIFICATIONS Tj+1 Tj + specifications: p, F, a, b, Q, R
Qreb Packed Catalytic Distillation Column: Control and Measuring Devices
Cooling W I I 1 Water M Operating Parameters: FIR LIRC Distillate 1 1
FIR 2 PIRC l Operating pressure, p 1 PDIR el. 2 TIRC 1.1 Packing l Reflux ratio, r TIR 1-5 of Catalytic Feed (F , a, b) m Rings l Heating rate, Qreb TIC el. 12-13 TIRC W I I 1.3 2 l Feed mass flow rate, Fm Packing TIR 6-10 of Inert l Molar feed composition: Rings TIR Bottom 11 a = Methanol/iso-Olefins Product LIRC M 2 b = iso-Olefins/Hydrocarb. Reboiler
W I I el. (Qreb ) 3 Catalytic Distillation Column for TAME-Production (Pseudohomogeneous Model)
MeOH1 Fm = 1,1 kg/h F F G/L/S x MeOH / x IA =Exp. 1,0 Data xF / xF = 0,3 1.6 Az2 IA C5 Simulation G/L p = 0,5 MPa
Experiment
r = 4 0.8 Equi. Nonequi. Simulation H Q = 520 W
[m] Reb 1.4 O e z M L , Experiment x
1.2 p = 0.5 MPa , Simulation r = 4 H
O 0.6 e Qreb = 520 W
1 M
Fm = 1.1 kg/h f o
a = MeOH/IA = 1.0 n
0.8 o i b = IA/(IA + nP) = 0.3 t 0.4 c a r
F Az1 0.6 e l o Column Coordinate M
0.4 . 0.2 T q i L Axial 0.2 M Reb B 0 0 TAME 0 0.2 0.4 0.6 0.8 1 80 90 100 110 120 130 L Liquid Phase Temperature, TL / [°C] Liq. Mole Fraction of C5, x C5
Sundmacher, K.; Gravekarstens, M.; Rapmund, P.; Thiel, C.; Hoffmann, U.: AIDIC Conf. Series 2 (1997) 215-221. Catalytic Distillation (CD) - Outline
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Experimental Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Influence of Reflux Ratio on Conversion
Conversion of Acetic Acid
Methyl Acetate Acetic Rectifying Section Acid (Rombopak 9M)
Catalytic Section (ICVT-Rings) Methanol Stripping Section (Rombopak 9M)
Water
There is an optimal reflux ratio !
Bessling, B.; Löning, J.M.; Ohligschläger, A.; Schembecker, G.; Sundmacher, K., Chem Eng. Technol. 21 (5), 393-400. Bifurcation Analysis of Catalytic Distillation Columns
MTBE process TAME process p = 11 bar p = 2 bar
R = L / D ] RD Zone -
MeOH + / [ (5 Stages) Olefins B
a = 1.0 Ether Stripping Zone x b = 0.30 (5 Stages) ] - 3 steady Qreb / [ states R Model 3 steady states l equilibrium stage approach Ratio, l overall efficiency E = 0.8 or 0.7 l MTBE: UNIQUAC; TAME: Wilson l heat losses along column Reflux l rate expression: r = r(T, a) Heating Rate, Qreb / [kW] Heating Rate, Qreb / [kW]
Mohl, K.-D.; Kienle, A.; Gilles, E.-D.; Rapmund, P.; Sundmacher, K.; Hoffmann, U., Chem. Eng. Sci. 54 (1999) 1029-1043. Multiple Steady States of TAME CD Column: Model Predictions and Experimental Results
Model Predictions Experimental Liquid Phase Temperatures ] - / [ B / [m ] TAME x z
, TIR 5
Heating Rate, Qreb / [kW] height / [m ]
z TIR10 Column , height Temperature, T / [°C] Column Temperature, T / [K] Mohl, K.-D.; Kienle, A.; Gilles, E.-D.; Rapmund, P.; Sundmacher, K.; Hoffmann, U., Chem. Eng. Sci. 54 (1999) 1029-1043. Oscillatory Behaviour of MTBE RD Columns
p » 6.5 bar
MeOH Experimental result R = 4...7 from lab scale column RD Zone
(Sundmacher and / [ml/min] C4 (GPP, 0.5 m) L
Hoffmann, 1995) , Stripping Zone (0.5 m)
Q = 560 W Reflux a = 1.0 reb b = 0.3 Time, t / [s] ] p = 11 bar - R = 7
Predictions based on / [
RD model implemented IB Rectification Zone X (2 Stages) in SPEEDUP IB, MeOH + RD Zone (Schrans et al., 1996) C4 (8 Stages)
Stripping Zone (5 Stages) a = 1.1 Conversion b = 0.36 B Time, t / [h] ý tray / packing hydraulics can lead to conjugate complex eigenvalues of system matrix resulting in oscillatory behaviour by Hopf bifurcations. Catalytic Distillation (CD)
3 Catalysts for Use in CD Processes 4 Modelling, Simulation, Expérimental´Validation
2 Fields of Application, CD Lecture Process Examples 5 Operational Process Behaviour
1 Basic Principles of CD CD Expert !
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003 Acknowledgements
Many thanks for fruitful scientific co-operation with
§ Prof.-Ing. Achim Kienle, Dipl.-Ing. Erik Stein,
Dr. Zhiwen Qi, Dr. Aspi Kolah (all MPI-Magdeburg)
§ Dipl.-Ing. Klaus-Dieter Mohl (Stuttgart University)
§ Dr.-Ing. Ulrich Kunz, Prof. Dr.-Ing. Ulrich Hoffmann (TU Clausthal)
Many thanks to the FHI organisers for invitation!
Modern Methods in Heterogeneous Catalysis Research Fritz Haber Institute, Berlin, 14 November 2003