University of Nottingham activities

Focus on capacity building.

ASGARD facility for investigating CO2 release.

Is CHn -> C + n/2H2 a feasible route for carbon

sequestration and hydrogen production (catalytic cracking of hydrocarbons gases)?

Long-term CO2 utilisation - efficient catalysts

for photocatalytic CO2 reduction.

Artificial Soil Gassing And Response Detection

Mike Steven, Jeremy Colls & Karon SmithUniversity of Nottingham

Schools of Geography (MS) and Biosciences (JC&KS)

ASGARD

Co-funding from SRIF3 allowed the development of a “permanent” field experimental facility - ASGARD

The TSEC programme (UKCCSC) funded 13 months effort to establish and test ASGARD and to run one field season.

The ASGARD facility

Gas injection

Gas monitoring

Gas response

Gas store

Gas control

ASGARD Site layout 2006

GRASS

LINSEED

BARLEY

TES

T

N

rc

• Plots 2.5 m square• 8 plots of grass, linseed &

barley• 4 Gassed and 4 control

plots

• Gas injected at 0.6 m depth

• Plus 4 “remote” controls for grass (rc)

rc

ASGARD: achievements and plans

From TSEC study

• We can control CO2 release rates and soil concentrations.

• We can relate soil CO2 concentrations to fluxes into the atmosphere.

• We can detect CO2 induced stress effects in plants at soil concentrations of a few percent by remote sensing techniques.

• We can discriminate fossil and biogenic carbon by isotopic analysis.

Ongoing and future work

• Responses of plant root systems and effects on competition

• Stress sensitivities of different plant species determined by spectral responses

• Soil and soil water chemistry

• Effects of SO2 contamination in leaked CO2

• CO2 pathways in soil

• Ecosystem recovery after gassing

Is CHn -> C + n/2H2 a feasible route for carbon sequestration and hydrogen

production?

Colin Snape, Miguel Castro Diaz and Jamie Blackman

Catalytic cracking of hydrocarbon gases gives carbon nanofibres (CNFs).

Driven by the value and utility of the carbon.

CNFs – poor for hydrogen storage but OK as adsorbents

Building sector – cement and bricks combined account for ca. 5% global CO2 emissions.

Replacing existing building materials begins to look attractive as am means of avoiding CO2 emissions.

Still attractive if the yield of hydrogen is not that high (e.g. for coal cf. CH4).

Catalytic decomposition of methane over supported metal catalysts has been widely studied in recent years to produce hydrogen free of CO and CO2.

The highest amount of hydrogen per metal has been obtained with a Pd-Ni/CNF catalyst (ca. 16,000 molC/molPd+Ni) after 30 hours [1].

The challenge is to achieve these high conversions with lower cost catalysts (i.e. base metals).

An unsupported Ni-Cu (4:1 wt/wt) metal alloy catalyst has been studied for the catalytic decomposition of ethene at 650-700°C.

Hydrogen production via catalytic cracking of hydrocarbons

[1] Takenaka et al., Journal of Catalysis 220 (2003) 468-477.

Configuration

Pure C2H4 (60 ml min-1) was decomposed over 25-100 mg of catalyst precursor in a quartz tube reactor for 3-9 hours.

Hydrogen production via catalytic cracking

High H2 selectivities (>75%) and C2H4 conversions (>90%) were achieved before catalyst deactivation.

High yields of ca. 4,500 molC/mol(Cu+Ni) were achieved after 9 hours of reaction at 650oC.

CNFs produced at 650oC cf. amorphous carbon at 700oC.

Test 1 : 60ml/min at 650°C

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

Time (min)

Gas c

om

po

sitio

n (%

)

CH4 C2H4

C2H6 H2

Hydrogen production via catalytic cracking

Although the conversion of CH4 is thermodynamically less favourable, unsupported Ni-Cu alloy catalysts could provide high conversions because of their high activity at higher temperatures (i.e. 700°C).

Applied Catalysis paper in press.

Further avenues for support are being explored to take the concept forward, especially for carbons in buildings (Halloran paper).

Long Term CO2 Utilisation (M. W. George - Nottingham)

1-Year PDRA Aims:

• To develop efficient catalysts for photocatalytic CO2 reduction

• To develop viable catalysts via understanding catalytic mechanism

• Explore the use of supercritical CO2 (scCO2)

– a solvent with several advantages including

(i) highest possible concentration of CO2

(ii) improved mass transport and high diffusivity

(iii) opportunities for efficient recovery of products

CO2 Reduction If Nature Can Do It, Why Can't We?

Strategy for CO2 Reduction

Reduction of CO2 requires energy Photon as energy source (Photochem)

Electricity as energy source (Electrochem)

Artificial photosynthesis for CO2 reduction typically requires:

photosensitizer, catalyst electron donor

Products are CO, formate, and H2

Co macrocycles

Ni macrocycles

Cobalt and Iron porphyrins,

Phthalocyanines and corroles

Ru(bpy)2(CO)X

Re(bpy)(CO)3X

Ni(bpy)32+

Re

N

NCl

CO

CO

CO

Re

N

NCl

CO

CO

CO

+-

Re

N

NCl

CO

CO

CO

-

charge separation

h

TEA

TEA+

Key Achievements:

• Strategic Alliance and Collaboration with leaders at Brookhaven National Laboratory (Fujita) in Photocatalytic CO2 reduction to develop catalysts for CO reduction in scCO2

• The promise of this new approach to CO2 reduction was picked up by the popular press and made front cover of CE&E news – key publication the American Chemical Society

• Development of catalyst which was soluble in scCO2

• Kinetic studies of mechanisms from picosecond (10-12 s) to seconds Mechanistic Studies to understand factors which affect solvent control of the catalytic cycle

• Monitoring, for the first time, rate of Cl- from key catalytic intermediate providing the understanding how to design and develop viable new catalytic systems

2100 2050 2000 1950 1900 1850

0.00

0.04

0.08

0.12

0.16

Wavenumber/ cm-1

FTIR

-6

-4

-2

0

2

4

6

300 ns

2020

2007

1901

1920

2025

2063

1.4 ns

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6 1.4ns 2ns 2.9ns 4.1ns 5.9ns 8.4ns 12ns 50ns 300ns

A

bso

rba

nce

x 1

0-3

-5 0 5 10 15 20 25 30 35 40 45 50

0.0000

0.0005

0.0010

0.0015

0.0020 MLCT Data: Kineticdata_2063.82605Model: ExpDec1Equation: y = A1*exp(-x/t1) + y0Weighting: y No weighting Chi^2/DoF = 3.0237E-9R^2 = 0.99301 y0 -2.9572E-6 ±0.00001A1 0.00315 ±0.00011t1 2.44783 ±0.1248

Time ns

20

63

cm-1

0.0000

0.0005

0.0010

0.0015

0.0020

= 1ns

20

07

cm-1

A

bso

rba

nce

= 2ns

= 5ns

Phenazine

Data: Kineticdata_2007.12965Model: ExpDec2Equation: y = A1*exp(-x/t1) + A2*exp(-x/t2) + y0Weighting: y No weighting Chi^2/DoF = 2.5457E-9R^2 = 0.99191 y0 0.00025 ±0.00001A1 -0.00242 ±0.00017t1 0.64328 ±0.08106A2 0.00207 ±0.00016t2 5.07996 ±0.45935

Phen

Kinteic traces

-0.001

0.000

0.001

0.002

0.003

Data: Kineticdata_2023.00824Model: ExpDec1Equation: y = A1*exp(-x/t1) + y0Weighting: y No weighting Chi^2/DoF = 1.7941E-8R^2 = 0.9852 y0 0.00256 ±0.00004A1 -0.00426 ±0.00019t1 5.04402 ±0.39287

20

23

cm-1

= 5ns

A few nanosecondsA few seconds

•1-Year funding developed science which resulted in being invited to join a consortium with UEA (Pickett/Nann); York (Perutz); Manchester (Flavell) to develop a new approach to artificial photosynthesis which was recently funded (ca. £1.5 M - £300 k to Nottingham) under EPSRC Solar Energy Initiative

Carbon Dioxide and Alkanes as Electron-sink and Source in a Solar Nanocell: towards Tandem Photosynthesis of Carbon Monoxide and

Methanol

•This proposal exploits the knowledge gained out of this one year funding.

Long Term CO2 Utilisation – future work