Experimental investigation of the reverse

water-gas shift reaction at high temperature

and elevated pressure

Sandra Adelung, Torsten Ascher, Fabian Klein, Ralph-Uwe Dietrich

Motivation: IATA Technology Roadmap

4. Edition, June 2013

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 2

3

Motivation: IATA Technology Roadmap

4. Edition, June 2013

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 3

Main goals:

Improvement of fuel

efficiency about 1.5 %

p.a. until 2020

Carbon-neutral

growth from 2020

50 % reduction of

CO2 emissions by

2050

1

2

3

1 2

3

Closing the gap: ICAO vision (2017) → “Power-to-Liquids:

Sustainable alternative fuels produced from renewable electricity”

Power-to-Liquid Process

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 4

CO2

3 H2

Electrolysis

Quelle: DLR

Production

of Syngas

CO

+

2 H2

Fischer-

Tropsch-

Synthesis

Liquid

Fuels

Carbon source:

• Power/ Industrial Plant

• Air

CO2 capture

• high volumetric

energy density

• easy to handle

• existing

infrastructure

𝑅𝑊𝐺𝑆: 𝐶𝑂2 + 𝑯𝟐 ⇌ 𝐶𝑂 + 𝑯𝟐𝑶 △ 𝑅𝐻0

298 = 𝟒𝟏 𝒌𝑱/𝒎𝒐𝒍

CO2, H2, light hydrocarbons, CO, H2O

Renewable electricity:

• Solar

• Wind

Increasing temperature…

→ Temperature range: 700-900 °C

Decreasing pressure…

→ Pressure range: 1-25 bar (FTS at 25 bar)

Power-to-Liquid Process – RWGS operating conditions

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 5

0

0,05

0,1

0,15

0,2

0,25

300 500 700 900 1100

Mo

lar

frac

tio

n /

(m

ol/

mo

l)

Temperature / °C

CO_Equilibrium

1 bar 25 bar

• Reaction kinetics • Equilibrium composition

• Less coke, CH4 • More CO

• Material • Catalyst sintering • High costs for reactor

• Thermal energy demand?

• Equilibrium composition • Less coke, CH4 • More CO

• Higher work-input for compression of recycle stream

Feed: H2/CO2 = 3

Most investigations at elevated pressure use high

temperature steel or stainless steel reactors

• Bustamente et al. (2004) found high CO2 conversion in an Inconel reactor

RWGS in Inconel 600 reactor

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 7

• Conversion was found to be 2

orders of magnitude higher than

in quartz glass reactor

• Inconel 600: approx. 72 % Ni-

content, Nickel catalyzes

reaction

RWGS in stainless steel reactor

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 8

• H2/CO2 = 1.7

• Residence time τ ≈ 5 s

• Pressure p = 1.5 bar

Stainless steel (1.4571) with 10.5-13.5 % Nickel content

• Equilibrium composition (Gibbs in Aspen Plus with CO, CH4 and C as

possible products) reached for T > 600 °C

• To investigate performance of catalyst: High temperature zones must

be inert (e.g. by using quartz glass)

1E-03

1E-02

1E-01

1E+00

200 400 600 800

CO

2 co

nve

rsio

n /

-

Temperature / °C

Equilibrium

Experiment

Novel reactor concept

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 10

Challenges:

• High temperature zone: inert

• Thermal expansion (Glass vs. Metal)

• High stress for reactor wall due to high temperature and elevated pressure

Novel reactor concept

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 11

Challenges:

• High temperature zone: inert

• Thermal expansion (Glass vs. Metal)

• High stress for reactor wall due to high temperature and elevated pressure

Novel reactor concept

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 12

Challenges:

• High temperature zone: inert

• Thermal expansion (Glass vs. Metal)

• High stress for reactor wall due to high temperature and elevated pressure

Novel reactor concept

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 13

Challenges:

• High temperature zone: inert

• Thermal expansion (Glass vs. Metal)

• High stress for reactor wall due to high temperature and elevated pressure

Novel reactor concept

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 14

Challenges:

• High temperature zone: inert

• Thermal expansion (Glass vs. Metal)

• High stress for reactor wall due to high temperature and elevated pressure

T >>

∆p <<

T <<

∆p >>

Reactor setup

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 15

Process scheme

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 16

H₂O reservoir

filter 1

vaporiser

condensatereservoir

aerosolfilter

TH2O

TMIX

coolingtrap

F

gas analysis

exhaust air

MFC CO2

LFM H₂O

MFM product gas

TOUT

MFC CO

MFC H2

MFC CH4

PI-2

PI-1

MFC N2

MFC syn. Air

gas bag for GC

analysis

PI-2

PI-4

PI-2

PI-3

TGAS

TVOR

TWENDEL

TK1 TK2

reactor

quartz glass

isolation

pump

TIN

Experimental results in new reactor

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 17

• H2/CO2 = 2

• Residence time τ ≈ 2 s

• Pressure p = 25 bar

1E-03

1E-02

1E-01

1E+00

650 750 850 950

CO

2 c

on

vers

ion

/ -

Temperature / °C

Equilibrium

Experiment

• Before: equilibrium composition reached above 600 °C

• With new setup:

• CO2 conversion in empty tube can be decreased significantly (below 2 %)

• Catalyst’s performance can be investigated with new reactor

First results with noble catalyst (0.1 g catalyst)

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 18

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

600 650 700 750 800 850 900 950 1000

CO

2 c

on

vers

ion

/ -

Temperature / °C

Feed 2 Equil 2 Feed 1 Equil 1 Feed 3 Equil 3

Feed p Vtot H2 CO2

bar LN/min LN/min LN/min

1 25 10 4 2

2 25 10 2 1

3 25 20 4 2

CO2 conversion reaches 50-60 %

of equilibrium conversion

Concentration doubled: slight

increase in CO2 conversion

Residence time halved: significant

decrease in CO2 conversion

Summary

• Investigation of RWGS at elevated pressure relevant in PTL concept

• RWGS significantly catalyzed by stainless steel

• New reactor concept allows investigation of catalyst‘s performance

at up to 900 °C and up to 25 bar

Outlook

• Kinetic performance of monolithic catalysts?

• Coke formation?

Summary and Outlook

> Experimental investigation of the reverse water-gas shift reaction at high temperature and elevated pressure > Sandra Adelung • WCCE10 DLR.de • Chart 19

Thank you for your attention

Sandra Adelung

Institute of Engineering Thermodynamics

German Aerospace Center