Is oxidative coupling the royal road for the valorization of methane to olefines?

Unifying Concepts in Catalysis

Cluster of Excellence

Is oxidative coupling the royal road

for the valorization of methane to olefines?

R. Schomäcker, V. Fleischer, S. Parishan, J. Sauer, M. Baldowski,

K. Kwarpien, A. Thomas, S. Mavlyankariev, R. Horn, A. Trunschke,

P. Schwach, R. Schlögl, Y.Cui, N. Nilius, H.J. Freund, F. Rosowski

U. Simon, M. Yildiz, O. Görke, H. Godini, G. Wozny

Presentation at „Changing Landscape…“-Workshop,

Oxidative coupling of methane is economically viable, if:

- added value is high

- methane is not wasted

- energy demand is appropriate

- capital expenditure is reasonable

Pioneering work

1985 1990 1995 2000 2005 2010

Reihe1

G.F. Keller, M.M. Bhasin,

J. Catal. 1982, 73, 9

catalyst

M. Hinsen, M. Baerns,

Chem. Z. 1983, 107, 223

catalyst

A.C. Jones, J.J. Leonardo et al., US patent 4 443644, 1984

periodic feed

strategy

U. Zavyalova, M. Holen, R. Schlögl, M. Baerms, ChemCatChem, 2011, 3, 1935

Milestone 1: The Lunsford Mechanism of OCM

•

Optimal loading for initial activity: 0.5 wt% Li/MgO

•

No stable Li/MgO-catalyst

•

Still active after Li-Loss

•

No selectivity

Z. Stansch, L. Mleczko, M.B. ,

Ind. Eng. Chem. Res. 1997, 36, 2568

LaO₂O₃ (27at%)/CaO

Milestone 3: Mn-doped Na

₂

WO

₄

/SiO

₂

U. Simon, O. Görke, A. Bertold, S. Arndt, R. Schomäcker, H. Schubert, Chem. Eng. J.168 (2011) 1352-1359

X.Fang et al, J. Mol. Catal. (China), 6 (1992) 427

H. Liu, X. Wang, D. Yang, R. Gao, Z. Wang, J. Yang, J. Nat. Gas. Chem. 17 (2008) 59

D.J. Wang, M.P. Rosynek, J.H. Lunsford, J. Catal. 155 (1995) 390

200 g batches with spray drying technology

O

₂

O

₂-

_O

_O

-

[1] C. Louis, T.L. Chang, M. Kermarec, T. Le Van, J.M. Tatibuët, M. Che, Colloids Surfaces A Physicochem. Eng. Asp. 72 (1993) 217 [2] T. Levan, M. Che, J.M. Tatibouet, M. Kermarec, J. Catal. 142 (1993) 18

[3] J.-L. Dubois, M. Bisiaux, H. Mimoun, C.J. Cameron, Chem. Soc. Japan Chemistry (1990) 967 [4] M.S. Palmer, M. Neurock, M.M. Olken, J. Am. Chem. Soc. 124 (2002) 8452

[5] C. Lin, K.D. Campbell, J. Wang, J.H. Lunsford, J. Phys. Chem. 90 (1986) 534 [6] Y. Sekine, K. Tanaka, M. Matsukata, E. Kikuchi, Energy and Fuels 23 (2009) 613 [7] C. Au, T. Zhou, W. Lai, C. Ng, Catal. Letters 49 (1997) 53

[8] V.J. Ferreira, P. Tavares, J.L. Figueiredo, J.L. Faria, Catal. Commun. 42 (2013) 50

[9] S. Gadewar, S.A. Sardar, P. Grosso, A. Zhang, V. Julka, P. Stolmanov, Continuous Process for Converting Natural Gas to Liquid Hydrocarbons, U.S. Patent US8921625B2, 2014 (Siluria Technologies)

Who is who in OCM

* Web of Science, 25.7.2014

* table adopted from E. V. Kondratenko, M. Baerns

Handbook of Heterogeneous Catalysis, Vol. 6, Ch. 13.17, 2008

The UNICAT concept

Multi scale approach for atomic to plant level

Model studies for understanding complexity

Multi scale approach to OCM

J. Sauer

M. Scheffler

R. Horn

R. Schomäcker

R. Schlögl

H.J. Freund

T. Risse

G. Wozny

M. Kraume

H. Schubert

A. Thomas

Mechanism of Oxidative Coupling of Methane

Origin of low selectivity

- OCM is initiated by oxygen activation (AFM, DFT, Model catalysts)

- Selective and inselective oxygen species at all catalysts (TAP, TPSR)

- Electron donors (dopants, defects) cause oxygen dissociation (AFM, Model catalyst) - Formation of methyl radicals at selective oxygen species (Kinetics, KIE, Model cat.) - Combustion of methane at inselective species (Kinetics, KIE)

- Parallel gas phase combustion at increased oxygen partial pressure (Profile R.)

2 CH

₄

+ O

₂

→ C

₂

H

₄

+ 2 H

₂

O

(+ CO

₂

)

K. Kwapien, J.Paier, J. Sauer, M. Geske, U. Zavyalowa, R. Horn, P. Schwach, A. Trunschke, R. Schlögl, Angew. Chem. Int, Ed. 2014, 53, 11-6 Y. Cui, X. Shao, M. Baldofski, J. Sauer, N. Nilius, H.J. Freund, Angew.Chem.Int.Ed. 2013, 52, 11385

The Puzzle of Information

How to get started?

Searching for more pieces?

2

2

Experiments in a TAP reactor

- Increasing delay of CH

₄

leads to decrease of CO

₂

and C

₂

H

₆

stays constant

- weakly adsorbed oxygen

leads to total oxidation

* + O

₂

*O

₂

- strongly adsorbed oxygen

is responsible for methyl

radical formation

* + O *O

- smaller ratio between

weakly and strongly

adsorbed oxygen at

Mn/Na

₂

WO

₄

/SiO

₂

Dynamic experiment

2

750 °C, 30 nml/min, 1g catalyst S(C2) = 0.89

• C2 Selectivity unexpacted

high in dynamic experiments at constant temperature

• less oxygen species on the

2

Kwapien, Paier, Sauer, Geske, Zavyalova, Horn,

Schwach, Trunschke, Schlögl, Angew. Chem. Int. Ed., 2014, 53, 8774

HT-MgO S-MgO

Mg oxidation

C-MgO

Ultra pure commercial MgO

SG-MgO

Sol-gel synthesis

Hydrothermal post treatment

MW-MgO

Hydrothermal post treatment in microwave autoclave

t = 0 h

t = 6 h t = 66 h

t = 230 h

t = 25 h

Deactivation of C-MgO

P. Schwach, M. G. Willinger, A. Trunschke, R. Schlögl ,

Angewandte Chemie International Edition 2013, 52, 11381–11384

Structure sensitivity of MgO during reaction

Kwapien, Paier, Sauer, Geske, Zavyalova, Horn,

Schwach, Trunschke, Schlögl, Angew. Chem. Int. Ed., 2014, 53, 8774

Eley-Rideal mechanism

• CH₄ adsorbes and is activated

• O₂ leads to methyl radical formation

Mechanism of OCM at MgO

Kwapien, Paier, Sauer, Geske, Zavyalova, Horn,

Mechanism of OCM at MgO

d(O-O)/d(Mg-O)

_122/215

_127/227

_135/253

~O

₂

Kwapien, Paier, Sauer, Geske, Zavyalova, Horn,

Mechanism:

•Mo-donors in CaO transfer charges

into O₂ molecules bound to surface

• Formation of pre-disscoiated O₂-

species

• Final dissociation via electron tunneling from STM tip

Experimental evidence:

• Work function increase after O₂ dosage only in the case of doped films

• no O₂ adsorption at 300 K for pristine CaO

Mo-doped CaO films on Mo(001)

Mo-doped CaO films on Mo(001)

8.0nm

8.0nm

As dosed O

₂

: Molecular species

(scanning below 2.5 V sample bias)

After dissociation with STM tip

(electron injection with 3.0 eV energy)

O₂ O-O

Doping of MgO with Fe

OCM on MgO

[1] K. Kwapien, J. Paier, J. Sauer, M. Geske, U. Zavyalova, R. Horn, P. Schwach, A. Trunschke, R. Schlögl, Angew. Chemie - Int. Ed. 53 (2014) 8774 [2] P. Schwach, M.G. Willinger, A. Trunschke, R. Schlögl, Angew. Chemie - Int. Ed. 52 (2013) 11381

[3] H. Yamamoto, H.Y. Chu, M.T. Xu, C.L. Shi, J.H. Lunsford, 142 (1993) 325

EA 0K [kJ/mol]

Gibbs Free Energy, 1013 K, 0.1 MPa

Bi-metallic Na

₂

WO

₄

/Mn/SiO

₂

catalysts for OCM

• Provides/stores

lattice oxygen

• Works without gas

phase oxygen

• Deep oxidation

catalyst for methane

• Selective OCM

catalysts

• Needs oxygen

source to form methyl radicals

OCM in transient experiments

Support variation for Mn

_x

O

_y

/Na

₂

WO

₄

/SiO

₂

Mn(ac)₂ ·4 H₂O Na₂WO₄ · 2 H₂O

Calcination

750°C Impregnation

commercial

nanostructured (SBA-15)

pre-catalyst _catalyst

silica support

Up-scaling of catalyst synthesis

Distribution of Mn-Na₂WO₄ on

Green - W

Red - Mn

nanostructured (SBA-15) commercial

silica supports

Support variation for Mn

_x

O

_y

/Na

₂

WO

₄

/SiO

₂

M. Yildiz, U. Simon, T. Otremba, K. Kailasam, Y. Aksu, A. Thomas, R. Schomäcker, S. Arndt Catalysis Today2014, 228, 5-14 H.R. Godini, A. Gili, O. Görke, S. Arndt, U. Simon, A. Thomas, R. Schomäcker, G. Wozny, Catalysis Today, 2014, DOI

X

Mn-Na2WO4/SBA-15

Mn-Na₂WO₄/commercial silica

Support variation for Mn

_x

O

_y

/Na

₂

WO

₄

/SiO

₂

Testing in lab scale reactor at 750 °C (C

₂

-Yield= 12 %)

X

X

M. Yildiz, Y. Aksu, U. Simon, K. Kailasam, O. Goerke, F. Rosowski, R. Schomäcker, A. Thomas, S. Arndt Chem. Commun. 2014, 50, 14440

Dynamic Experiments

•

At reaction temperature the

catalyst is

oxidized by air

•

Reactor is

purged with Helium

to remove oxygen in gas phase

and weakly adsorbed one

•

Defined amount of

methane is

dosed

into the reactor

•

Reaction mixture is analysed

by mass spectroscopy



Catalyst activity can be

analyzed without gas phase

oxidation reactions

Repetitive dynamic experiments

• Repetitive methane pulses

allow to study the available amount of oxygen

Mol

efra

ction

(%)

Na₂WO₄ (5%)/Mn(2%)@Quartz Na₂WO₄ (5%)/Mn(2%)@SBA15

O

₂

O

_2,ads

O

₂-

_HO

[1] B. Beck, V. Fleischer, S. Arndt, M.G. Hevia, A. Urakawa, P. Hugo, R. Schomäcker, Catal. Today 228 (2014) 212 [2] S. Ji, T. Xiao, S. Li, C. Xu, R. Hou, K.S. Coleman, M.L.H. Green, Appl. Catal. 225 (2002) 271

• Infeasibility of various spectroscopic techniques

• mechanism proposed by analogy to other systems

OCM in a mini-plant reactor

Fluidized Bed Reactor

37

+

Isothermal reaction

- Sensitive to free gas volume

2%Mn-2.2%Na₂WO₄/SiO₂ catalyst, particle size 250-450 μm Bed height: 10 cm, CH₄:O₂ = 1.7 to 10,

OCM membrane reactor set-up

Performance indicators of the membrane reactor

2%Mn-5%Na₂WO₄/SiO₂ catalyst (4 g), average particle size 250-450 μm

Reactor concept: Chemical looping

Operation steps:

1. O₂ is dosed to oxidize the catalyst

2. Reactor is purged with inert gas to remove gas phase oxygen

3. CH₄ dosage to perform

OCM

Early pulses Late pulses

Continuous operation

Early pulses Late pulses

Continuous operation

800°C

Economic Analysis

Simulations with Aspen Plus & Aspen Process Economic Analyzer v8.8

Production capacity is one million tonnes per year

Ethylene price 947 Euro/tone

1. Case I (OCM Reaction Unit + CO

₂

separation Unit+Demethanizer

Unit+C

₂

-Splitter Unit)

2. Case II (OCM Reaction Unit + CO

₂

separation Unit + Demethanizer

Unit + C

₂

-Splitter Unit + Ethane Dehydrogenation Unit)

44

OCM to Ethylene (Case I)

OCM reactor: Mn-Na2WO4/SiO2 catalyst

Membrane reactor (40% conv. & 62% sel.)

<5% N2 , dense membrane, air separation

Amine scrubbing (30%wt MEA)

Energy needed: 8 GJ/t-CO₂

Energy cost associated: 14.3 €/t-CO₂

Propylene-cryogenic media cycle Energy needed: 4.7 GJ/t-CO₂ Cost associated: 8.8 €/t-C₂H₄

99.8 % Ethylen purity Methane-cryogenic media cycle

Energy needed: 4.8 GJ/t-CO₂

OCM reactor:

Mn-Na₂WO₄/SiO₂ cat.

40% conv. 62% sel. air separation

EDH reactor (60% conv. & 65% sel.) Conventional performance

Propylene-cryogenic media cycle Energy needed: 3.8 GJ/t-C₂H₄ Cost associated: 7.3 €/t-C₂H₄

99.9 % Ethylen purity Methane-cryogenic media cycle Energy needed: 6.5 GJ/t-C₂H₄ Cost associated: 120.5 €/t-C₂H₄

Amine scrubbing (30%wt MEA)

Energy needed: 5.8 GJ/t-CO₂

Energy cost associated: 12.8 €/t-CO₂

Compression

Energy needed: 0.4 GJ/t-C₂H₄ Electricity cost: 8.6 €/t-C₂H₄

EDH reactor (58% conv. & 63% sel.) Conventional performance

Amine scrubbing (30%wt MEA)+Membrane (Hybrid)

Energy needed: 10.93 GJ/t-CO₂ Energy cost associated: 22 €/t-CO₂

OCM reactor:

Mn-Na₂WO₄/SiO₂ cat.

40% conv. 62% sel. air separation

PSA/TSA activated carbon

Energy needed: 1.10 GJ/t-C₂H₄

Energy cost associated: 11.11 €/t-C₂H₄

Propylene-cryogenic media cycle Energy needed: 3.38 GJ/t-C₂H₄ Cost associated: 10.42 €/t-C₂H₄

Results of Economic Analysis

Economic Parameter Case I Case II Case III

(Millions € per year)

Project Capital Cost 414 334 398

Operating Cost 962 907 820

Raw Material Cost 485 485 485

Utilities Cost 418 368 247

Product (C₂H₄) Sales 1020 1136 1208

Desired Rate of Return 15% 15% 15%

Demethanizer

Further Modifications:

Autothermal Reactor

CO₂ Separation Reactor

OCM

OCM integrated with dry reforming of methane

Further Options:

OCM with methanol OCM with styrene

-

The puzzling informations about OCM are essembled

in a complete picture

- Oxygen activation is the key step in OCM mechanism

- Selectivity is controlled by

different oxygen species

- Implications for new catalyst materials and their synthesis

- single phase, highly conductive, non-reducible, e-donor/acceptor

- New options with chemical looping technology

- Techno-economic analysis shows potential for further optimization

Acknowledgments

The authors acknowledge the support from the Cluster of Excellence

„Unifying Concepts in Catalysis" coordinated by the Berlin Institute of

Technology - Technische Universität Berlin and funded by the German

research foundation - Deutsche Forschungsgesellschaft

–

DFG .

ThyssenKrupp Uhde

Thank you for the attention!