“Electrocatalytic conversion of CO into energy...

Jesús García, Susana Tostón, Carlos Jiménez, Fabiola Martínez, Rafael Camarillo, Isaac Asencio and Jesusa Rincón

Department of Chemical Engineering, University of Castilla-La Mancha

Faculty of Environmental Sciences and Biochemistry Avda. Carlos III, s/n, 45071, Toledo, Spain

E-mail: [email protected]

“Electrocatalytic conversion of CO2

into energy compounds”

Toledo, 22nd of November 2013

-Sustainability and waste treatment-

Energy and Environment Knowledge Week – E2KW 2013 -

INDEX OF CONTENTS

1. Introduction. 2. Objetive of this work.

3. Metodology. 4. Results.

5. Conclusions.

1. Introduction: Global warming, CO2...

The latest IPCC reports (3rd, 4th y 5th)

[CO2]

Use

fossil fuels

Therefore:

Earth temperature

In the last 40 years, GHG

emissions have been

doubled (major

contributor: CO2, 75%)

Use fossil fuels

(main source of energy)

In recent decades

Technologies that avoid

these emissions

Renewable

energy

In this Century

Fossil fuels will remain the mainstay

of world energy production

Capture and Storage* of CO2

GLOBAL WARMING

Global warming

-CLIMATE CHANGE-

INTERNATIONAL ENERGY AGENCY

Recycling of CO2

(Complementary technology to storage)

1


Awareness GHG

emissions (especially CO2)

1. Introduction: Technologies of CO2 recycling.

Objetive: CO2 conversion to fuels and chemicals consumption or can be used

as raw material in the chemical industry.

Main CATALYTIC METHODS

of CO2 conversion:

1) Photocatalytic reduction of CO2.

2) Electrocatalytic reduction of CO2.

Chemical transformation of CO2

at ambient conditions requires a

high energy input

POSSIBLE SOLUTION:

Addressing

CO2 conversion reaction by

CATALYTIC METHODS

2


CHEMICAL REDUCTION OF CO2

USE FUELS:

-Electricity production -Industry, etc…

Fuels

Other products

CO2

CO2

Photocatalytic reduction of CO2 Electrocatalytic reduction of CO2

PhotoElectroCatalytic reduction of CO2

- Involve the use of semiconductors (photocatalysts),

substances that cause chemical reactions (redox) under

light.

- By the time the conversions achieved aren’t very high.

- Involve the use of electrocatalyst, substances that

promote chemical reactions (redox) in the presence of

electric power.

MAIN LIMITATION: low solubility of CO2 in water

when using aqueous solutions of CO2.

- The conversions achieved are higher than those

obtained in the photocatalytic process.

Scheme of a PEC reactor for reducing CO2 using sunlight

RESEARCH

SOLUTIONS:

Adapted from (Centi et al., 2007)

1) increasing the pressure and the CO2 concentration

in the system, but limit the effectiveness of the process.

2) performing the Photocatalytic or Electrocatalytic

conversion of CO2 in gas phase.

3) PhotoElectroCatalytic conversion of CO2 in gas phase

(alternative and complementary procedure).

3



PHOTO-catalysts ELECTRO-catalyst

sunlight

2. Objetive.

The objective of this work is to develop an

electrocatalytic system that allows, through the use of

electrocatalysts, the conversion of CO2 in gas phase to

hydrocarbons (liquid fuels easy to store and transport)

using electrical current to activate them.

4


3. Metodology.

Electrochemical cell used

It has been carried out the assembly and

tuning up of an installation for

electrochemical reduction of CO2 to

hydrocarbons through the use of an

electrochemical cell.

5


Connections and operation of

the electrochemical cell

H2O

INLET

ANODIC ZONE CATHODIC ZONE

H2O

OUTLET

Heater cartridge

Thermocouple

CO2

INLET

CO2 + REACTION PRODUCTS

OUTLET

Electrical connection (RE+CE)

Electrical connection (WE)

Electrooxidation of H2O for generate H+ and e-

Electroreduction of CO2 to hydrocarbons using H+ and e-

generated in the electrooxidation

Main component of this cell

Membrane Electrode Assembly

(MEA)

TO ACHIEVE THIS OBJETIVE…

Flow diagrams of the experimental installation of electrocatalysis

(continuous operation)

CO2 BOTTLE

6


3. Metodology.

POTENCIOSTAT-GALVANOSTAT

TEMPERATURE CONTROLLER

PUMP - aquous solution of KHCO3 -

ELECTROCHEMICALCELL HUMIDIFIER

TANK - aquous solution of KHCO3 -

Thermocouple

Heater

cartridge

WE

CE + RE

CO2

FLOWMETER

to GC-FID-TCD

CO2 +

REACTION

PRODUCTS

OUTLET

Configuration to channel reaction products leaving the cell and to analyze them

by gas chromatography

7


3. Metodology.

GC-FID-TCD

decane

in

Liquid products trapped in decane

are preconcentrated and injected in GC

Gaseous products released from decane

are injected in GC

Cooling bath (-5 °C)

Solids filter

CO2 +

REACTION

PRODUCTS

OUTLET Heater cord temperature (130 - 140 °C)

1) Reaction products trapped

in liquid absorbent (decane)

2) Gaseous products released

from the liquid absorbent

Identification

with GC-FID-TCD

(* pA: picoamps; μV: microvolts; min: minutes)

Identification

8


4. Results.

“Configuration to channel reaction products leaving the cell“

1) Reaction products trapped in

decane

Preconcentrated and injected

in GC-FID-TCD

(* pA: picoamps; min: minutes)

- Methanol and acetone have been identified.

- The peak whose retention time is 26.3 min.

can be isopropanol or methyl acetate.

It’s necessary to study new temperature ramps.

- There are peaks without identification.

Conditions experiment 12:

-CO2 flow= 250cm3 min-1

-KHCO3 concentration= 0.025 mol/l

-Current intensity= 0.54 A (Galvanostatic mode)

-Cell temperature= 60 °C

-Cell pressure= 1 atm


4. Results.


It’s necessary to inject other patterns.

Comments:

9

2) Gaseous products released from

liquid absorbent (decane) Injected in GC-FID-TCD

(* pA: picoamps; min: minutes)

- Carbon monoxide (CO) has been identified.

- In the 5 minute there are a peak without identification.

(* μV: microvolts; min: minutes)

- Hydrogen (H2) has been identified.


4. Results.


It’s necessary to inject other patterns.

10

Through the use of an electrochemical cell similar to PEM fuel cells is possible to

obtain fuel products from CO2 reduction.


5. Conclusions.

The configuration to channel reaction products which consisted in the absorption

of the reactions products in a cold trap, with decane as absorbing liquid, and their

preconcentration and subsequent injection into GC-FID-TCD has allowed to

identify compounds liquid fuels such as methanol and acetone, and gaseous

compounds such as carbon monoxide and hydrogen.

Upcoming work includes:

Deposition of metals on carbon nanotubes in supercritical media to create

advanced electrocatalysts.

Identification and quantification of all products attained.

11

Thanks for your attention!

Presented by: Jesús García García

E-mail: [email protected]

“Electrocatalytic conversion of CO2

into energy compounds”

Toledo, 22nd of November 2013

1. Introduction: Technologies of CO2 capture and storage.

Objetivo: evitar que las emisiones antropogénicas de CO2 alcancen la atmósfera.

Captura Almacenamiento Transporte

Absorción en disoluciones

no acuosas de aminas.

En formaciones geológicas:

- Minas subterráneas.

- Sumideros terrestres

(depósitos agotados de

carbón, petróleo,…).

- Océanos.

Implica: gasto adicional de

energía Emisiones

de CO2.

PROBLEMÁTICA CCS:

- Necesario acondicionar los

lugares de almacenamiento

definitivo

- ¿Seguridad a largo plazo?

Actualmente

Reciclaje de CO2

(Tecnologías complementarias a

la de almacenamiento)

Contracorriente: flujo de

gas cargado de CO2 y la

disolución no acuosa de

aminas.


A FAVOR de estas tecnologías:

1) Grandes cantidades de CO2

puro y a bajo coste.

2) Numerosas emisiones para

las que no es apropiada la

captura y almacenamiento

(distancia,…).

3) Buena imagen de la

empresa por adoptar política

de reducción de emisiones.

EN CONTRA de estas tecnologías:

1) Gasto adicional de energía Emisiones

de CO2

Solución: el aporte adicional de energía a de

proceder de una fuente renovable, como es la

solar.



3. Metodology. Celda

electroquímica

Componentes

principales de la

celda electroquímica

EME

*

MEMBRANA PROTÓNICA

SOPORTES CARBONOSOS PARA LOS ELECTRODOS

JUNTA SELLANTE

JUNTA SELLANTE

PLACA BIPOLAR DEL

ÁNODO

PLACA BIPOLAR DEL

CÁTODO

*

Proceso preparación EME:

1) Preparar electrodos.

2) Ensamblar electrodo-membrana-electrodo.

3) Montaje en celda.

Montaje final de la celda electroquímica

PLACA COLECTORA

PLACA DEL ÁNODO

PLACA DEL CÁTODO

JUNTA AISLANTE

JUNTA AISLANTE

PLACA COLECTORA

Adaptado de (Linares, 2009)

Se ha llevado a cabo el montaje y puesta a

punto de una instalación de reducción

electroquímica de CO2 a hidrocarburos

mediante el empleo de una celda

electroquímica.


3. Metodology.

Conexiones y funcionamiento

de la celda electroquímica

ENTRADA H2O

COMPARTIMENTO ANÓDICO

COMPARTIMENTO CATÓDICO

SALIDA H2O

Cartucho calefactor

Termopar

ENTRADA CO2

SALIDA CO2 +

PRODUCTOS REACCIÓN

Conexión eléctrica (RE+CE)

Conexión eléctrica (WE)

Electrooxidación de H2O para generar H+ y e-

Electrorredución de CO2 a hidrocarburos empleando los H+ y e-

generados en la electrooxidación

Disposición de las conexiones eléctricas en la celda electroquímica

WE en cátodo

CE-RE en ánodo

y viceversa

WE en cátodo

CE en ánodo

RE en cable (EME)

EME





WE

RE

WE CE

Permite controlar el voltaje de la celda

- Permite controlar el voltaje catódico – Descartada problemas RE-cable EME

CE-RE

1 2


Flow diagrams experimental installation of electrocatalysis

(continuous operation)

POTENCIOSTAT-GALVANOSTAT

TEMPERATURE CONTROLLER

PUMP - aquous solution of KHCO3 -

ELECTROCHEMICALCELL HUMIDIFIER

CO2 BOTTLE

TANK - aquous solution of KHCO3 -

Thermocouple

Cartridge

heater

WE

CE + RE

CO2

FLOWMETER

6


3. Metodology.

CO2 +

REACTION

PRODUCTS

OUTLET

Configurations for canalize reaction products leaving the cell, and so be able to

perform the same analysis by gas chromatography

7


3. Metodology.

4. Results.

“Experimentos con el objeto de

seleccionar la metodología más

adecuada para analizar la corriente

producto”

Configuración 1

Configuración 2

“Experimentos para el estudio

del comportamiento electroquímico

de los electrodos”

Método

Voltametría Cíclica Potenciostática

(VCP)

Configuración 3

9


ESTUDIO DEL COMPORTAMIENTO ELECTROQUÍMICO DE LOS

ELECTRODOS

VCP entre +4V y -4V

Voltaje negativo (catódico): picos de reducción.

Voltaje positivo (anódico): picos de oxidación.


4. Results.

4. Results.

“ESTUDIO DEL COMPORTAMIENTO ELECTROQUÍMICO DE LOS ELECTRODOS”

WE en cátodo

CE en ánodo

RE en cable (EME)

Voltajes negativos

(catódicos):

Condiciones experimento 2:

-Flujo CO2= 432cm3 min-1

-Concentración KHCO3= 0,5 mol/l

-VCP= entre -0,4 V y 0 V

-Tª en celda= 25 °C

-Presión en celda= 1 atm

VCP: barrido de voltaje para

analizar los cambios en la

intensidad de corriente como

consecuencia de las reacciones

redox que ocurren en la celda.

Reducción de H2O

-0,2V

Reducción de CO2

-0,38V

Picos reacciones de

reducción

- Pico de reducción de

CO2 a -0,2V.

- Pico de reducción de

H2O a -0,38V.

Conclusiones:

1) La aplicación del método VCP a una celda electroquímica permite determinar la existencia de

reacciones redox.

2) Los picos de las reacciones de reducción aparecen cuando los voltajes son negativos.

10


4. Results.

“Experiments with the aim of selecting the most appropriate

methodology to analyze the product stream”

Configuration 1 Configuration 2 Configuration 3

9


Configuration 1

“STUDY OF THE MOST APPROPRIATE METHODOLOGY TO ANALYZE THE PRODUCT STREAM“

1-pentanol absorption Decane absorption

Conditions in experiment 3:



-Voltage= -2.8 V (Potenciostatic mode)



Conditions in experiment 4:




-Cell temperatura= 60 °C


25%

Acetone

1.690

83%

1- pentanol

3.520 – 9.840

4%

CO2

1.494

1- pentanol absorption (GC-MSD)

30%

Acetone

1.489

94%

Decane

8.326 – 12.228

4%

CO2

1.320 Decane

absorption (GC-MSD)

Configuration 1 conclusions:

1) The probability with which the MSD identifies the acetone in both chromatograms isn’t high

enough for us to say that acetone is formed in the reaction CO2 conversion.

2) Other reaction products (overlapped with the peak of absorbing liquid or its concentration is

below DL).

Configuración 2 is proposed…

11


4. Results.

Configuration 2

Conditions experiment 5: Conditions experiment 7:








-Current intensity= 0.54 A (Galvanostatic mode)



Ethylene oxide 4%

Acetaldehyde 3%

CO2 2%

2,426 – 3,766

Injection at 2 hours (GC-MSD)

Formaldehyde

2%

2,366 – 3,478

Methanol 1%

7,621 – 8,549

12


4. Results.

“STUDY OF THE MOST APPROPRIATE METHODOLOGY TO ANALYZE THE PRODUCT STREAM“

Configuration 2 conclusions:

1) The probability with which the MSD identifies the products isn’t high enough for us to say

that are those products which are formed from the reaction of CO2 conversion.

2) Obstruction problems occur in the heated pipe.

Configuration 3 is proposed…

Injection at 45 minutes

(GC-MSD)

Uso H2SO4 como electrolito:

1) evita problemas de obstrucción,

2) no mejora los resultados respecto al uso de KHCO3 y

3) podría afectar negativamente a los electrocatalizadores

Se retoma el uso de KHCO3 como electrolito pero en concentraciones inferiores a las usadas inicialmente.

Configuración 2

Condiciones experimento 9:

WE en cátodo

CE-RE en ánodo

Óxido de etileno 3%

Acetaldehído 3%

CO2 2%

2,556 – 3,834

Inyección a las 2 horas (GC-MSD)

-Flujo CO2= 250 cm3 min-1

-Concentración H2SO4= 1 mmol/l

-Intensidad de corriente= 0,54 amperios (Modo galvanostático)

-Tª en celda= 60 °C

-Presión en celda= 1 atm

13


4. Results.

“STUDY OF THE MOST APPROPRIATE METHODOLOGY TO ANALYZE THE PRODUCT STREAM“ Conclusiones Configuración 2:

1)La probabilidad con la que el MSD identifica los productos no es lo suficientemente alta como

para que podamos afirmar que son esos productos los que se forman a partir de la reacción de

conversión de CO2.

2)Surgen problemas de obstrucción en la tubería calefactada.

Se plantea la Configuración 3

CONFIGURACIÓN 1: Disoluciones de 1 y 5 ppm de metanol, etanol, acetona e

isopropanol (enrase decano)… En GC-MSD

Acetona 86%

4,232

Decano 97%

7,841 – 16,412

1ppm

Acetona 90%

3,683

Decano 95%

6,523 – 16,430

5ppm

“Solvent delay”


4. Results.

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