VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD

CO2 hydrogenation to methanolMaster’s thesis update

Christian Frilund20.10.2015

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Aim of the thesis

Overview of recent state of the art developments in catalytic hydrogenation of CO2 to methanol, focus on copper based catalysts

Special focus on process-intensifying coated catalysts and reactors that can enable small-scale Power-to-Liquid solutions.

Test new formulations of coated catalysts and powder catalysts in a CSTR, obtain basis of design for reactors

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About the project

Started working on this in late May in the Catalysis & Synfuels team VTT

Experimental testing to be completed within 1 month

Supervisor: Francisco Vidal (Paco)In-house catalyst preparation: Mari-Leena Koskinen-Soivi, Matti PutkonenExperimental set-up help: Matti Reinikainen, Mari-Leena Koskinen-Soivi

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Introduction

Paths to reduce CO2 emissions: 1) reduce produced CO2 amounts 2) store CO2 3) use CO2

In a “Methanol Economy” CO2 and renewable H2 would be converted to methanol. Methanol would act as an energy carrier easy, safe to handle

CO2 an attractive C1 building block, with currently limited usage because of its chemical inertness

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Methanol synthesis

Anthropogenic carbon cycle in the ”Methanol Economy” by George A. Olah:

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Conventional Methanol synthesis

Methanol properties: high octane rating, half the energy density of gasoline, suitable for flex fuel vehicles and fuel cells

Produced from syngas, with ideal H2/CO ratio of 2

CO + 2H CH OH H = 90.5

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Methanol synthesis from CO2

CO2 hydrogenation: CO + 3H CH OH + H O H = 49.5

Reverse water-gas-shift (rWGS): CO + H CO + H O H = 41

CO2 hydrogenation has the same reaction network as the syngas route but with different feed compositions.

Cu/ZnO or Pd based catalysts, T = 200 – 300 oC and P = 30 – 100 bar

Methanol yield lower than for syngas produced route

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Methanol synthesis from CO2: Conditions

Low temperature and high pressure preferred.Catalyst activation at over 200 oC!

0

2

4

6

8

10

200 210 220 230 240 250 260

mol

-%

T / Celsius

Equilibrium composition

MeOHCO

02468

10

30 40 50 60 70 80

mol

-%

P / Bar

Equilibrium composition

MeOHCO

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Copper-based catalysts

Cu main active component. Modifiers include Zn, Zr. Typical catalyst being Cu/ZnO/Al2O3

Syngas catalysts deactivate prematurely at high CO2 levels. The water produced in CO2 hydrogenation also deactivates catalysts. Special formulations of catalysts for CO2 hydrogenation needed!

Small-scale decentralized production of methanol requires more robust catalysts

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Cu-based catalysts – Reaction conditions

CO2 conversion increases with increasing temperature, however selectivity to MeOH decreases Maximum MeOHyield typically at 230-250 oC (at 30 – 80 bar)

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Cu-based catalysts

Reaction is catalyst surface sensitive Catalyst preparation methods affect performance significantly

There is important synergy between the copper metal and oxide (ZnO or ZrO2). Reactions occurs at the interfaces.

Thermal sintering at over 300 oC

Reaction mechanism is still debated Better understanding of mechanism is needed to produce more effective catalysts.

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Cu-based catalysts: Kinetics

CO2 hydrogenation: =.

.

..

Reverse water-gas shift: =.

.

Where fi is fugacity for species i.

Fitted against large number of experiments at 207-277 oC and 15 – 50 bar with conventional CuO/ZnO/Al2O3 catalyst

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Coated catalysts

Produced by depositing thin catalyst layer on a monolith or reactor wall more favourable loading of catalyst than conventional packing, interesting for intensified reactorsCoating must be sufficiently thick and homogeneous, mechanically and thermally stableWashcoating most common coating technique Structure submerged in solution

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Coated catalytic reactors

Example: Monolithic reactors:Benefits: high surface areas without high pressure drop, less intraporous mass transfer limitations, easy scale-up

Especially useful for small scale

Issues: ceramic monoliths have bad radial heat transfer, difficult catalyst replacement

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Industrial status of CO2 hydrogenation to methnanol

First CO2-to-methanol plant in Iceland Uses cheap geothermal energy to produce the H2

Bottleneck is the cost of renewable energy for water electrolysis (H2 production)PtL case: Nuclear power off-peak capacity could be used to produce renewable methanolChallenges: Catalyst improvements, reactors for small-scale production of methanol near the renewable energy source needed

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Experimental setup

TIC

HIGH PRESSUREAUTOCLAVE

N2

FC

MIX

FC

BYPASS LINE

OUTLET

VENTDRY GAS

WATER ANDMETHANOL

CONDENSATE

HEATING JACKET

PC

PI

HIGH PRESSURE:

50 bar

VENT

RUPTURE DISK

GC

FI

MIX23.75% CO271.25% H25% N2

INLET

Calib

FC

GC with TCD and FID detectors

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Experimental setup: CSTR

CSTR not typically used for gas-phase reactions Interest in seeing how it works

200 ml autoclave with heating jacket

Isothermal operation

Reacting gases enter autoclave through the hollow stirrer and exit from the top

Catalyst packing or mesh attached to stirrer

TIC

HIGH PRESSUREAUTOCLAVE

OUTLET

HEATING JACKET

RUPTURE DISK

INLET

Catalyst

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Experimental setup: Catalyst types

Two different catalyst types are tested:

1. Catalyst powder in a metallic basket

2. Catalyst coated on a metallic mesh

Gas In

Gas Out

Basket +Catalyst

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Initial experimental results: Catalyst powders

Powder catalyst testing done, coated mesh testing starts this week

Condition testing performed with commercial BASF RP-60 catalyst

Standard screening conditions for in-house catalysts:Temperature: 240 oCPressure: 50 Bar Flow rate: 0.185 l/min or 11.1 l/hCatalyst packing mass: ca. 2 gCatalyst particle size: 200 – 300 µmTime on stream: 3-4 h

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Effect of particle size BASF

Catalyst: BASF RP-60. mcat 2 gT = 240 oC, P = 50 bar, F = 0.185 l/minEquilibrium calculation property method: RKS MHV2

0

5

10

15

20

25

30

200-300 300-1000

CO2

con

vers

ion

(%)

Catalyst particle size / um

CO

MeOH

Conversion

Equilibriumconversion

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Effect of flow rate BASF

Catalyst: BASF RP-60. mcat 2 g, particle size = 200 – 300 µm T = 240 oC, P = 50 bar

0

5

10

15

20

25

30

0.0925 0.185 0.37

CO2

con

vers

ion

(%)

Operating flow rate / l/min

COMeOHConversionEquilibrium conversion

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Effect of pressure BASF

Catalyst: BASF RP-60. mcat 2 g, particle size = 200 – 300 µm T = 240 oC, F = 0.185 l/min

0

5

10

15

20

25

30

30 50

CO2

con

vers

ion

(%)

Operating pressure / Bar

COMeOHConversionEquilibrium conversion

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Effect of temperature BASF

Catalyst: BASF RP-60. mcat 2 g, particle size = 200 – 300 µm P = 50 bar, F = 0.185 l/min

05

10152025303540

200 220 240

CO2

con

vers

ion

(%)

Operating temperature / Celsius

CO

MeOH

Conversion

Equilibriumconversion

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In-house vs. commercial catalyst

NC = Nanocoating, mcat 1.4 - 2 g, particle size = 200 – 300 µm T = 240 oC, P = 50 bar, F = 0.185 l/min

0

5

10

15

20

25

30CO

2 c

onve

rsio

n (%

)

Catalyst

CO

MeOH

Conversion

Equilibriumconversion

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