molecular insights: towards process control with ... · c.b. minnich #, l. küpper*, m.kaever#, l....

C.B. Minnich #, L. Küpper*, M.Kaever#, L. Greiner#, M.A. Liauw#

#Institut für Technische und Makromolekulare ChemieChair of Industrial Chemistry and Reaction Engineering

RWTH Aachen University, Aachen/Germany*infrared fiber sensors, Aachen/Germany

Molecular Insights:

Towards Process Control with miniaturised fibre optical

ATR-infrared sensors

EuroPACT 2008, Frankfurt April 25th 2008

Clemens Minnich RWTH Aachen University

Vision: „tapless tap reactor“

continuous flow reactor

- 2 -





inline chemical sensors

- 2 -





inline chemical sensors

➢ small reactor volumes (1-5 mL) ==> sampling disadvantageous➢ locally structured reaction spaces➢ minimisation of sensor impact➢ no distortion of steady states➢ measurement in reactive mixtures

- 2 -



Process Example: N-alkylation of amines

- 3 -




non-catalytic reactive mixtures! solvent-free (monophasic) exothermic (∆rHm ≈ -120 kJ mol-1; ∆Tad ≈ 220 K) moderately fast

- 3 -




non-catalytic reactive mixtures! solvent-free (monophasic) exothermic (∆rHm ≈ -120 kJ mol-1; ∆Tad ≈ 220 K) moderately fast

analytical tools required for:reaction monitoring, process monitoring, process controloffline, atline,offline, atline, onlineonline, inlineinline

no chance for chromatography, (NMR), …

promising: optical methods (MIR, UV-VIS)

- 3 -



Advantages of fibre optical ATR-midIR spectroscopy

- 4 -




MIR: the “molecular view inside”

ATR: simplified beam paths;optically dense media

fibres: flexible orientation

- 4 -




Relevant features for µRT:

➢ miniaturised reflection elements available➢ maintaining the setup mobility➢ “numbering up” (multiplexing)

MIR: the “molecular view inside”

ATR: simplified beam paths;optically dense media

fibres: flexible orientation

- 4 -



Basic evaluation for the model system

reflection element: diamond ATR-prism

6 mm shaft with fitting

DiProbe, infrared fiber sensors, Aachen/Germany

- 5 -



Basic evaluation for the model system

pure component spectra show good discrimination

reflection element: diamond ATR-prism

6 mm shaft with fitting

DiProbe, infrared fiber sensors, Aachen/Germany

- 5 -



Small-scale batches (0.5 – 2 mL)*

3 mL and 1 mL vials

- 6 -



Small-scale batches (0.5 – 2 mL)*

3 mL and 1 mL vials

chemometric models (PLS, hard modeling)#

# E. Kriesten, F. Alsmeyer, C.B. Minnich, L. Greiner, W. Marquardt, submitted.# C.B. Minnich, M. Nieren, L. Küpper, M.A. Liauw, L. Greiner, in preparation.* C.B. Minnich, P. Buskens, L. Küpper, W. Leitner, M.A. Liauw, L. Greiner, Org. Proc. Res. Dev. 2007, 11, 94-97.

- 6 -



Modular continuous flow reaction setup

total volume: 300 µL – 8 mL

- 7 -



Mixer by IMM (Mainz/Germany).

micro mixer



- 7 -



residence time

module



- 7 -





- 7 -



Spectrometer supplied by BrukerOptics, Ettlingen/Germany.

- 8 -



Adaptation of flow cell geometries

optimised flow geometry:

sample fluid

structured housing

probe head with ATR element

from reaction capillary

hold-up volume: 20 µL

cooling fluid sample fluid

- 9 -



Adaptation of flow cell geometries

optimised flow geometry:

sample fluid

structured housing

probe head with ATR element

from reaction capillary

hold-up volume: 20 µL

cooling fluid sample fluid

W. Hempelmann, L. Greiner, C.B. Minnich, DE 102007013607.4

increased stability of concentration signal

- 9 -



Applications

non-reactive tracer system:

equipment characterisation

reactive system:

process characterisation (amine alkylation)

- 10 -



Non-reactive tracer system

ν(C=O)

2-octanone / n-octane

easy handling

low volatility

high absorptivity of ketone

appropriate MIR marker system

- 11 -



Calibration of mixtures (PLS)

• 63 samples, duplicated

• cross-validated (leave-out 1)

RMSECV = 879 ppm

- 12 -



n-Octane [mmol/mol]R² = 100.00

RMSECV = 0.879 mmol/mol

2-Octanone [mmol/mol]R² = 100.00

RMSECV = 0.879 mmol/mol

Calibration of mixtures (PLS)

• 63 samples, duplicated

• cross-validated (leave-out 1)

RMSECV = 879 ppm

Both (complementary) concentration signals are useful for evaluation.

- 12 -



Linear offset correction in the range:

1734 – 1718 cm-1

Estimation of detection limit in static samples

3σ-criterion already fulfilled below 1500 ppm

- 13 -



Characterisation of residence time behaviour

step change of marker and inert solvent

concentration measurements at module inlet and outlet

marker inert

- 14 -





concentration measurements at module inlet and outlet

marker inerttime resolution in multiplex mode not satisfactory for dynamic operation:

~15 s @ 2 sensors

reduction to one single sensor:

~3 s @ 1 sensor

- 14 -





concentration measurements at module inlet OR outlet

marker inert

- 15 -



marker inert


separation of individual pulses (replicates)

offset correction and normalisation

- 16 -



marker inert


normalisation: F(t) or F(θ)

derivation: E(t) or E(θ)

- 17 -



Applications

non-reactive tracer system:

equipment characterisation

reactive system:

process characterisation (amine alkylation)

- 18 -



offline monitoring (NMR; samples from the reactor outlet; quenched with a primary amine)

Steady-state concentration profiles from micro plant*

- 19 -



offline monitoring (NMR; samples from the reactor outlet; quenched with a primary amine)

Steady-state concentration profiles from micro plant*

* reported in:C.B. Minnich, L. Küpper, M.A. Liauw, L. Greiner, Catalysis Today 2007, 126(1-2), 191.

inline monitoring (ATR-IR)

- 19 -



Validation of process insights from inline spectroscopy:Reaction calorimetry (differential kinetics)*

* Zogg, A.; Fischer, U.; Hungerbühler, K. Chem. Eng. Sci. 2004, 59, 5795.

- 20 -

Heat flow profile from semi-batch# experiments:

➢ substrate A charged➢ injections of substrate B

# protocol suggested in:Blackmond, D. G.; Rosner, T. & Pfaltz, A. Org. Proc. Res. Dev., 1999, 3, 275.



Conclusions on kinetics and thermodynamics

MIM in DES

heat flows from semi-batches

DES in MIM

- 21 -




DES in MIM


MIM in DES

- 21 -





MIM in DES

DES in MIM

C.B. Minnich, L. Küpper, M.A. Liauw, L. Greiner, Catalysis Today 2007, 126(1-2), 191–195.

- 21 -

apparent ∆rHm varies with conversion



Available kinetic models (2nd order)* cannot explain our data.

Fundamental problems with the inclusion of endothermal contributions to the heat flow signal.

* a) A. Renken, V. Hessel, P. Löb, R. Miszczuk, M. Uerdingen, L. Kiwi-Minsker, Chem. Eng. Proc. 2007, 46, 840; b) A. Große Böwing, A. Jess,

Chem. Eng. Sc. 2007, 62, 1760; c) A. Große Böwing, A. Jess, P. Wasserscheid, Chem. Ing. Tech. 2005, 77, 1430.

- 22 -







gPROMS modelling and parameter estimation

Input: heat flows, concentrations from IRSo far, model discrimination with heat flows yields:

• No confirmation for 2nd order kinetics.

• No one-step reaction, but more complex network.

• No autocatalysis.

• (to be continued)

C.B. Minnich, M. Zavrel et al., work in progress.

- 22 -



Summary

power of scaleable inline analytical tools

tapless tap reactor available (0.3 – 8 mL)

concepts for modular lab-scale continuous setup

equipment characterisation (RTD)

- 23 -



Summary

power of scaleable inline analytical tools

tapless tap reactor available (0.3 – 8 mL)

concepts for modular lab-scale continuous setup

equipment characterisation (RTD)

Outlook

3rd generation ATR flow cell (under construction)

structured reactor geometries for scale-up

kinetic modelling for process example in progress

- 23 -



Thanks for extensive scientific & technical & experimental support:

R. Thelen, H. Kronenberg, R. Sojka (ITMC/RWTH)

W. Hempelmann (MMT GmbH, Siegen)

Dr. H. Lutz, Dr. A. Simon, Dr. A. Rager (BrukerOptics, Ettlingen)

M. Nieren, M. Kessel, H. Schulte, F. Sipeer (ITMC/RWTH)

E. Kriesten, M. Zavrel (AVT/RWTH)

Dr. N. Theyssen, A. Brinkmann (MPI für Kohlenforschung, Mülheim)

Funding by the European Commission (IP IMPULSE, NMP 011816) is gratefully acknowledged.

Special thanks to the Organising Committee for a EuroPACT student grant.

- 24 -







simulated heat flow for experimental protocol:b)

DES in MIM

reac

tion

heat

flow

[W],

mol

ar fr

actio

ns

MIM in DES

reac

tion

heat

flow

[W],

mol

ar fr

actio

ns

- App. A -



1st iteration of Experimental Design*

* Performed with the gPROMS OED tool.

fed-batch (stepwise) in reaction calorimeter

MIM charged

DES feed at various flow rates

- App. B -



Scale-Up targets (IMPULSE Demonstrator activities)

increased production rates

new geometries for structured reactors

characterisation of new geometries

iterative adaptation of sensors

robust control system based on true kinetics

(automated) optimisation of process regimes

reliable intervention in case of off-spec production

SHE issues

and many more…

- App. C -

molecular insights: towards process control with ... · c.b. minnich #, l. küpper*, m.kaever#, l....

Documents