Instrumentations for Monitoring Microreaction Processes · Betriebsversammlung ICT 18.10.1999 9 sl / µ / 2006 online NIR and Raman spectroscopy 1000110012001300140015001600 0.0 0.1

Betriebsversammlung ICT 18.10.1999

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CPAC Satellite Workshop, March 2006

Instrumentations for Monitoring Microreaction Processes

Stefan Löbbecke

Fraunhofer Institute for Chemical Technology ICTPfinztal, Germany

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motivation

Monitoring the Chemistry• products

• conversion

• mechanism

• thermokinetic data

• …

Monitoring Process Parameters• T, p, flow, pH, …

Monitoring Fluid Dynamics• flow distribution

• residence time distribution

• …


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motivation

process diagnosticsmechanistic, kinetic studies

safety analysis

…

qualification of microfluidic structures

mixing performance

RTD

…

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www.microreaction-technology.info

motivation

process optimizationparameter screenings

automation


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challenges

spatial resolution

time resolution

sensitivity

…

interfacing

hold-up

thermal control

…

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online infrared spectroscopy: using silicon microreactors


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↓ reactant 1

reactant 2 ↓

↑ product

online infrared spectroscopy: using silicon microreactors

mixing principle:split-and-recombine

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online infrared spectroscopy with FTIR microscopy


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hydrolysis of benzoyl chlorideO Cl

+ H2O

O OH

+ HCl

benzoic acid (product; reference)

benzoyl chloride (educt; reference)

reactor outlet

online infrared spectroscopy with FTIR microscopy

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nitration of N,N‘-dialkyl substituted ureas

NR

H

O

N R

H

NR

NO2

O

N R

H

NR

NO2

O

N R

NO2

+

nitrating agent

(e.g. HNO3, HNO3/H2SO4,

N2O5, ...)

N N

R

NO2

R

NO2

DNDA (energetic plastiziser)

R = alkyl

+ ...

(S)

macroscopic batch reactor: -20°C/-30°C; mixtures of mono- and dinitro substituted

ureas; other by-products; target product < 10%

microreactor: room temperature; one main product with selectivity > 95%


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reactor entrancereactor centerreactor outlet

nitration of dialkyl subst. thioureas: online analysis in microreactors

synthesis of N-nitroso-N,N´-diethyl-urea: reaction progress along a microreactor channel

1722

15301480

NC2H5

H

O

N C2H5

NO

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concentration profiles in individual microreactor channels

channel 4

00,010,020,030,040,050,06

1 2 3 4 5 6position

conc

entr

atio

n D

ND

EH /

(m

ol/L

)channel 1

00,010,020,030,040,050,06

1 2 3 4 5 6position

conc

entrat

ion

DN

DEH

/ (m

ol/L

)

channel 6

0

0,010,02

0,030,04

0,050,06

1 2 3 4 5 6position

conc

entr

atio

n D

ND

EH /

(m

ol/L

)

nitration of dialkyl subst. thioureas: online analysis in microreactors


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thermography: monitoring of the entire microreaction process

L RP

nitration of ureas with N2O5/CH2Cl2

• „micro hot spots“

• fluctuations in flow behavior, inhomogeneous flow distribution

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Re-designed microfluidic split-and-recombine structures

out

in 2

in 1in 1 in 2out

(patented by MERCK, WO 96/30113 )

Corporate TechnologyAutomation & Drives


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• homogenous flow distribution

• improved mixing quality


Re-designed microfluidic split-and-recombine structures

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5 10 15 200,0

0,1

0,2

0,3

0,4

E(t)

t / s

split-and-recombine Reaktor (type a) split-and-recombine Reaktor (type b)

(patented by MERCK, WO 96/30113 )(Design: Siemens, AuMµRes)

Re-designed microfluidic split-and-recombine structures: RTD


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online NIR and Raman spectroscopy

1000 1100 1200 1300 1400 1500 1600

0.0

0.1

0.2

0.3

0.4

Ext

inkt

ion

Wellenlänge [nm]

p2 4

(AOTF)-NIR monitoring of HNO3 consumption

wavelength / nm

abso

rban

ce

O

Cl HOOC

O

Cl HOOC

NO2

nitrating agent

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CH3

CH3

NO2

CH3CH3

NO2NO2

+ +HNO3

CH3

NO2O2NCH3

NO2

NO2

+ +

online spectroscopy: quantitative analysis during process screenings

2000 1750 1500 1250 1000 750 500 250

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Inte

nsitä

t

Shift /cm-1

HNO3

Toluol

2-Nitro

3-Nitro

4-Nitro

Reaktion-mischung

Inte

nsity

reaction mixture


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online spectroscopy combined with defined quenching and subsequent HPLC/GC analysis: chemometric calibration for quantitative analysis

for homogeneous reaction mixures for heterogeneous reaction mixures

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quantitative online Raman spectroscopy: nitration of toluene

D e s ir a b il i ty

B: T

empe

ratur

2 . 0 2 . 5 3 . 0 3 . 5 4 . 0

1 5 .0 0

1 7 .5 0

2 0 .0 0

2 2 .5 0

2 5 .0 0

0 . 0 0 0

0 .0 0 0

0 .0 0 0

0 .0 0 0

0 . 0 0 0 0 .0 0 0

0 . 0 0 1

0 .0 0 1

0 . 0 0 1

0 . 0 0 1 0 .0 0 1

0 . 0 0 1

0 .0 0 1

0 . 0 0 1

0 .0 0 1

0 . 0 0 1

0 . 0 0 1

0 . 0 0 1

0 . 0 0 1

0 .0 0 1

0 . 0 0 1

0 . 0 0 2

0 . 0 0 2

P r e di c t i o 5 . 2 4 9 E - 0 0 3

p-nitrotoluene

stoichiometry

flow

tem

pera

ture

CH3

NO2

CH3

NO2


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ATR-MIR(UV/VIS) NIR

Raman

microreactorinlet 1

inlet 2 residence time unit

quench reactor

offline-analysis

quenching agent

quantitative online spectroscopy for screening purposes

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ATR-FTIR

Raman

UV/Vis/NIR


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0

1

2

3

4

5

0 1 2 3 4 5predicted /mol-%

mea

sure

d /m

ol-%

0

1

2

3

4

5

0 1 2 3 4 5predicted /mol-%

mea

sure

d /m

ol-%

0.9770.9779correlation

0.2090.1965RMSECV /mol-%RamanNIR

NIR

3-nitrotoluene

Raman

RMSECV: Root Mean Square Error of Cross Validation

quantitative monitoring of individual species in reaction mixtures

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goal: determination of thermodynamic and kinetic parameters of strong exothermic reactions

calorimetric monitoring of microreaction processes

new approach:

combined use of microreactors and thermoelectric modules

•safe processing

•small hold-ups

•improved heat transfer characteristics

development of a µL-flowthrough

calorimeter on basis of microreactors

embedded between Seebeck and

Peltier elements


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reactants quench and products

cryostat

metal housing

µL-flowthrough calorimeter »concal« on basis of microreactors embedded between Seebeck and Peltier elements

thermofoil for calibration

set-up of the continuous µL calorimeter (»concal«)

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use of a special designed, flat split-and-recombine microreactor made of glass

quench

outletinlet 1

inlet 2

set-up of the continuous µL calorimeter (»concal«)


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nitration of toluene with 100% fuming HNO3 (offline analysis by GC)

toluene flow / (mL/min)

P (

mea

sure

d)

/W

50°C

examplary measurements

NO2

NO2

NO2

+ +HNO3

• heat (power) increases linear with volume flow

• from slope: calculation of ∆HR

• varied residence time: 4s - 32s

• conversion even at 4s: 100% → short time constant!

• measured ∆HR = 110 kJ/mol (Lit.: 105-135 kJ/mol)

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NH3C

NO2

O

N CH3

NO2

nitrating agent

NH3C

H

O

N CH3

H

nitration of N,N‘-dimethyl urea

urea flow / (mL/min)

P (

mea

sure

d)

/W

10°C

heat (power) increases linear with volume flow

controlled measurement of extremely high reaction enthalpies, here: ∆HR = 280 kJ/mol (reaction

mixture) => decomposition reactions in parallel

safe processing even under conditions of decomposition

fast quantitative screening for safety analyses of exothermic reactions

examplary measurements


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detection limits and time constants

comparison of different commercially available reaction calorimeters with respect to their

relative detection limits (W/L) and time constants

Std. RC: RC1 (Mettler), Sysalco (Systag), Simular (HEL); CPA 200 (Chemisens), autoMate (HEL, small scale); C80 DRC (Setaram);

DSC: Differential Scanning Calorimeter)

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enhancing spatial resolution and sensititvity


16

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thermo foil

microreactor

heat

heat

n Seebeck elements

Seebeck

element

Peltier element


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1

2

3

1

2

3

measurement of mixing enthalpy, e.g. acetone/water

acetone flow/ (mmol/s)

P (

mea

sure

d) /

W

∆Hm 601 J/mol, Lit.: 575-620 J/mol

xacetone: 0.2



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automated microreaction system: AuMµRes


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microstructured mass flow sensor based on the Coriolis princple


(flow-through design, corrosion resistant)

microstructured mass flow and density

sensor based on the Coriolis princple

microstructured process sensors: mass flow


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microstructured mass flow sensor and density

based on the Coriolis princple


(flow-through design, corrosion resistant)

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mass flow sensor for density measurements

0,0150

0,0180

0,0210

0,0240

0,00 0,20 0,40 0,60 0,80 1,00

density / (g/cm3)

1/f R

²

resonance frequency depends on density (here: water/ethanol mixtures)




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flow–through design

pressure range 0-10 bar

temperature range < 200°C

dead volume < 0.5 µL

corrosion resistant


microstructured process sensors: pressure + temperature

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Jürgen Antes

Dusan Bošković

Wolfgang Ferstl

Klaus Huber

Horst Krause

Gunnar Kronis

Eric Marioth

Slobodan Panić

Harald Polifke

Björn Richert

Daniel Schifferdecker

Frank Schnürer

Heike Schuppler

Maud Schwarzer

Wenka Schweikert

Tobias Türcke

…

Financial support:

Federal Ministry of Eduction and Research (BMBF)

ICT staff:Acknowledgements

Documents

Instrumentations for Monitoring Microreaction Processes · Betriebsversammlung ICT 18.10.1999 9 sl / µ / 2006 online NIR and Raman spectroscopy 1000110012001300140015001600 0.0 0.1