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A microstructured membrane reactor system for dehydrogenation of liquid organic hydrogen carriers Energie Lab 2.0 meets Neo Carbon Energy Workshop Helsinki 15.02.17 Martin Cholewa Institute for Micro Process Engineering H 2 H 2 www.kit.edu

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SLIDE 1

H2 H2

KIT – The Research University in the Helmholtz Association

Institute for Micro Process Engineering

www.kit.edu

A microstructured membrane reactor system for dehydrogenation of liquid organic hydrogen carriers

Energie Lab 2.0 meets Neo Carbon Energy Workshop Helsinki 15.02.17– Martin Cholewa

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SLIDE 2

Institute for Micro Process Engineering, KIT 2 Martin Cholewa – Workshop Helsinki

Outline

Introduction of LOHC

Background Reactor concept

Results

Experiments with the membrane modules Simulation High pressure experiments

Summary and Outlook

28.02.2017

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SLIDE 3

Institute for Micro Process Engineering, KIT 3

Introduction

Martin Cholewa – Workshop Helsinki 28.02.2017

  • Storage and transport of hydrogen
  • Hydrogen used in a fuel cell or ic-

engine

Dehydrogenation

H2

Hydrogenation

H2 lean H2 rich

H2

Charge:

Hydrogenation of unloaded carrier

Storing:

Organic kept at room temperature

Discharge:

Dehydrogenation at ~ 200-400 °C

1 J. von Wild, R. Freymann and M. Zenner, Potentiale von alternativen Wasserstoffspeicherungstechnologien, VDI-Berichte: Innovative Fahrzeugantriebe, 2008, vol. 2030, pp. 273–298

Energy density of various hydrogen storage systems for mobility.1

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Institute for Micro Process Engineering, KIT 4 Martin Cholewa – Workshop Helsinki

Introduction

Liquid Organic Hydrogen Carrier + Can use the existing distribution ways + No high pressure or low temperature is needed + High energy density

ΔHR(298 K)= + 204.8 kJ/mol

Methylcyclohexane

ΔHR(298 K)= + 639 kJ/mol

Perhydro-dibenzyl-toluene1

1: Brückner, N., Obesser, K., Bösmann, A., Teichmann, D., Arlt, W., Dungs, J. and Wasserscheid, P. (2014), Evaluation of Industrially Applied Heat-Transfer Fluids as Liquid Organic Hydrogen Carrier Systems. ChemSusChem, 7: 229–235.

+ 68.3 kJ mol-1 H2 + 71 kJ mol-1 H2

Hydrogen mass capacity: ~ 6.2 wt.% ~ 600 Nm3 H2 / m3 LOHC

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SLIDE 5

Institute for Micro Process Engineering, KIT 5

Membrane reactor

In-situ hydrogen removal

Martin Cholewa – Workshop Helsinki

  • Integration of membranes: Beneficial for

reaction and separation

  • In-situ selective H2 removal shifts

reaction equilibrium to product side

  • H2 purification directly from reaction

zone

Heating Pd-Membrane Reaction Separation Catalyst

Pd-based membrane

H2 MCH TLU + 3 H2

28.02.2017

  • Microchannels: Highly efficient

heat and mass transfer

  • High surface to volume ratio
  • Good thermal coupling of

endothermic reaction and heating zone

  • High system compactness
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SLIDE 6

Institute for Micro Process Engineering, KIT 6

Membrane reactor In-situ hydrogen removal

Martin Cholewa – Workshop Helsinki 28.02.2017

Holder

  • Swagelock fitting for

connection to the experimental setup

  • electrically heated
  • Reactor plate for catalyst bed with

pillars

  • Microchannels for transport of the

permeated hydrogen

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SLIDE 7

Institute for Micro Process Engineering, KIT 7

Membrane reactor

In-situ hydrogen removal

Martin Cholewa – Workshop Helsinki 28.02.2017

catalyst powder

pillar

H2

pillar

Metal sheet with 70 µm holes

Feed/Retentate: catalytic fixed-bed, 4 pillars in width

zone length: 20 mm, distance pillars: 1 mm

Permeate: 17 microchannels, length: 20 mm, width: 0.2 mm

Pd membrane: 12.5 μm thick

catalyst powder

pillar

H2

pillar

1 mm

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SLIDE 8

Institute for Micro Process Engineering, KIT 8

Membrane Reactor

Thermodynamics

Martin Cholewa – Workshop Helsinki 28.02.2017 20 40 60 0.0 0.5 1.0

conversion [-] pressure [bar] T = 623 K T = 673 K T = 573 K

500 600 700 0.0 0.5 1.0

conversion / - Temperature / K p = 1 bar p = 30 bar

500 600 700 0.0 0.5 1.0

conversion / - Temperature / K p = 1 bar p = 30 bar p= 30 bar, pm = 3 bar

High Temperature and low pressure preferred – endothermic reaction

  • Membrane could avoid limitation
  • with 3 bar permeate pressure still

high separation and conversion

  • Steep decrease of conversion

with higher pressure

  • Temperature as driving force
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SLIDE 9

Institute for Micro Process Engineering, KIT 9

Experimental

Martin Cholewa – Workshop Helsinki 28.02.2017

Catalyst 1 wt.% Pt - Al2O3

BET-surface in m²/gcat 28.9 Dispersion in % 47.4 Size in µm 200 – 300 (particle)

Pt distribution (EPMA recording)

Reaction/ Reactor conditions varied:

  • Pressure 9 - 30 bar
  • Bed height 500 - 2000 µm
  • Membrane thickness 4 - 16 µm

Is the hydrogen separation efficient ? How stable are the membrane and the catalyst ?

50 µm

  • H. Kreuder, Catalyst development for the dehydrogenation of MCH in a microstructured membrane reactor - for heat storage

by a Liquid Organic Reaction Cycle. Cat. Today 242, 2015.

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Institute for Micro Process Engineering, KIT 10 Martin Cholewa – Workshop Helsinki 28.02.2017

Results Membrane reactor

1000 2000 3000 20 30 40 50 60 70 80 90 100

conversion / % tos / min Microreactor, 9 bar, 400 °C Berty, 1 bar, 365 °C Membrane, 9 bar, 350 °C

  • High Conversion
  • Good catalyst stability

200 400 600 800 1000 0.5 0.6 0.7 0.8 0.9 1.0

2000 µm 1000 µm 500 µm efficiency / -- flow rate / ml min

  • 1

catalyst bed height:

  • Good separation efficiency through

microchannels

Separation experiments with H2:N2 75:25 mixtures

pH2 pH2,perm p*H2

Membrane

Catalyst bed 200µm 2000µm

Influence of mass transfer ? Catalyst performance ?

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Institute for Micro Process Engineering, KIT 11 Martin Cholewa – Workshop Helsinki 28.02.2017

Results Membrane reactor

1000 2000 3000 20 30 40 50 60 70 80 90 100

conversion / % tos / min Microreactor, 9 bar, 400 °C Berty, 1 bar, 365 °C Membrane, 9 bar, 350 °C

  • High Conversion
  • Good catalyst stability

200 400 600 800 1000 0.5 0.6 0.7 0.8 0.9 1.0

2000 µm 1000 µm 500 µm efficiency / -- flow rate / ml min

  • 1

catalyst bed height:

  • Good separation efficiency through

microchannels

Separation experiments with H2:N2 75:25 mixtures

Influence of mass transfer ? Catalyst performance ?

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SLIDE 12

Institute for Micro Process Engineering, KIT 12

Results membrane modules

Comparison

  • Thinner membrane shows

despite of lower conversion same level of hydrogen separation

  • Still total separation is low

Martin Cholewa – Workshop Helsinki 28.02.2017

MCH conversion with 1wt.% Pt/Al2O3 catalyst in membrane module, tmod = 250 kg s m-3, p = 9 bar, T=350° C

Redesign of the module for the existing test rig

500 1000 1500 0.00 0.25 0.50 0.75 1.00

Conversion MCH / - tos / min 12 µm Pd - Membrane 4 µm Pd - Membrane

0.00 0.25 0.50 0.75 1.00

hydrogen recovery factor / -

ሶ nH2,perm ሶ nH2,total

Hydrogen recovery factor:

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SLIDE 13

Institute for Micro Process Engineering, KIT 13

Simulation

Optimization with 1-D model

Martin Cholewa – Workshop Helsinki 28.02.2017

Comparison with simulation at T=350 °C, tmod = 125 kg s m-3

Conclusion from Experiments and Simulation:

  • lower bed depth
  • Higher membrane area to

catalyst ratio Constant reactor volume but 4 times higher membrane surface area

8.0E+05 1.0E+06 1.2E+06 1.4E+06 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Conversion, hydrogen recovery / - pressure / Pa / Simulation original module / Exp.

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SLIDE 14

Institute for Micro Process Engineering, KIT 14

Simulation

Optimization with 1-D model

Martin Cholewa – Workshop Helsinki 28.02.2017

Extrapolation with simulation for new geometry at T=350 °C, tmod = 125 kg s m-3

Reactor is wider and longer

8.0E+05 1.0E+06 1.2E+06 1.4E+06 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Conversion, hydrogen recovery / - pressure / Pa / Simulation original module / Simulation rescaled module / Exp.

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SLIDE 15

Institute for Micro Process Engineering, KIT 15

Results

Comparison between large and small module

Martin Cholewa – Workshop Helsinki 28.02.2017

  • Higher hydrogen

recovery and conversion of MCH at same pressure level

at 9 bar to 13 bar, 350 °C and τmod= 125 (kg s)/m³ 500 1000 1500 2000 2500 3000 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Conversion Methylcyclohexane / - tos / min small module (12 µm membrane) large module (16 µm membrane)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

hydrogen recovery factor / -

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SLIDE 16

Institute for Micro Process Engineering, KIT 16

Results

High pressure experiment with large module

Martin Cholewa – Workshop Helsinki 28.02.2017

500 1000 1500 2000 2500 0.0 0.2 0.4 0.6 0.8 1.0

Conversion H2 recovery factor

tos / min Conversion / -

0.0 0.2 0.4 0.6 0.8 1.0 31 bar 28 bar 25 bar

Hydrogen recovery factor / -

  • Almost total amount of

hydrogen separated

  • But conversion

significantly lower

Conversion and hydrogen recovery at high pressures with module B at 350°C, tmod = 125 kg s m-3 , Separation efficiency was determined with measured permeate flow and calculated amount of produced hydrogen

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SLIDE 17

Institute for Micro Process Engineering, KIT 17

Membrane Stability

Influence of Regeneration

Martin Cholewa – Workshop Helsinki 28.02.2017

  • Coke can be removed by oxidation regeneration step and activity is restored

T = 350°C, p = 8 bar, τmod = 250 kg*s/m3, XEq = 99.5%

Regeneration of catalyst by oxidation at 400°C and following reduction

  • H. Kreuder et al., Heat storage by the dehydrogenation of methylcyclohexane - Experimental studies for the design of a microstructured

membrane reactor. International Journal of Hydrogen Energy, 2016

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Institute for Micro Process Engineering, KIT 18 Martin Cholewa – Workshop Helsinki 28.02.2017

Membrane Stability

Influence of Regeneration

  • Decrease in perm selectivity
  • Further steps will lead to

total damage of membrane

  • Slight increase of leakage

flow after regeneration for supported membrane

Measured with pure Nitrogen at T = 350°C, p = 8 bar

1x10

4

2x10

4

0,0000 0,0005 0,0010 0,0015 0,0020

without regeneration

  • 1. Regeneration
  • 2. Regeneration
  • 3. Regeneration

VN2 [ml/min] tos [min]

Tests with pure nitrogen as an indicator for leakages

  • H. Kreuder et al., Heat storage by the dehydrogenation of methylcyclohexane - Experimental studies for the design of a microstructured

membrane reactor. International Journal of Hydrogen Energy, 2016

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SLIDE 19

Institute for Micro Process Engineering, KIT 19

100 µm 100 µm

Martin Cholewa – Workshop Helsinki 28.02.2017

Membrane Stability

Analysis of used membranes

Without support With support Additional cracks due to pressure Only slight pitting due to regeneration 10 µm 6 µm

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Institute for Micro Process Engineering, KIT 20

Summary

LOHC concept for hydrogen storage with microstructured membrane reactor for enhanced reaction Successful test of different membrane module with methylcyclohexane as LOHC 1-D Simulation of module for an optimized membrane module

  • Further detailed studies of the optimized module
  • Combination of membrane with other LOHC reactor concept for liquid-

gas phase reaction

Martin Cholewa – Workshop Helsinki 28.02.2017

620 640 660 680 0.5 0.6 0.7 0.8 0.9 1.0

conversion / - Temperature / K / /

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

  • ptimized module
  • riginal module

hydrogen recovery factor / -

500 1000 1500 0.00 0.25 0.50 0.75 1.00

Conversion MCH / - tos / min Membrane A1 Membrane A2

0.00 0.25 0.50 0.75 1.00

hydrogen recovery factor / -

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Institute for Micro Process Engineering, KIT 21 Martin Cholewa – Workshop Helsinki 28.02.2017

Thank you for your attention Questions ?