Presentation on theme: "University of Nottingham activities Focus on capacity building. ASGARD facility for investigating CO 2 release. Is CH n -> C + n/2H 2 a feasible route."— Presentation transcript:
University of Nottingham activities Focus on capacity building. ASGARD facility for investigating CO 2 release. Is CH n -> C + n/2H 2 a feasible route for carbon sequestration and hydrogen production (catalytic cracking of hydrocarbons gases)? Long-term CO 2 utilisation - efficient catalysts for photocatalytic CO 2 reduction.
Artificial Soil Gassing And Response Detection Mike Steven, Jeremy Colls & Karon Smith University 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 TEST 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 CO 2 release rates and soil concentrations. We can relate soil CO 2 concentrations to fluxes into the atmosphere. We can detect CO 2 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 SO 2 contamination in leaked CO 2 CO 2 pathways in soil Ecosystem recovery after gassing
Is CH n -> C + n/2H 2 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 CO 2 emissions. Replacing existing building materials begins to look attractive as am means of avoiding CO 2 emissions. Still attractive if the yield of hydrogen is not that high (e.g. for coal cf. CH 4 ).
Catalytic decomposition of methane over supported metal catalysts has been widely studied in recent years to produce hydrogen free of CO and CO 2. The highest amount of hydrogen per metal has been obtained with a Pd-Ni/CNF catalyst (ca. 16,000 mol C /mol Pd+Ni ) after 30 hours . 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  Takenaka et al., Journal of Catalysis 220 (2003) 468-477. Configuration Pure C 2 H 4 (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 H 2 selectivities (>75%) and C 2 H 4 conversions (>90%) were achieved before catalyst deactivation. High yields of ca. 4,500 mol C /mol (Cu+Ni) were achieved after 9 hours of reaction at 650 o C. CNFs produced at 650 o C cf. amorphous carbon at 700 o C.
Hydrogen production via catalytic cracking Although the conversion of CH 4 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 CO 2 Utilisation (M. W. George - Nottingham) 1-Year PDRA Aims: To develop efficient catalysts for photocatalytic CO 2 reduction To develop viable catalysts via understanding catalytic mechanism Explore the use of supercritical CO 2 (scCO 2 ) – a solvent with several advantages including (i) highest possible concentration of CO 2 (ii) improved mass transport and high diffusivity (iii) opportunities for efficient recovery of products
CO 2 Reduction If Nature Can Do It, Why Can't We? Strategy for CO 2 Reduction Reduction of CO 2 requires energy Photon as energy source (Photochem) Electricity as energy source (Electrochem) Artificial photosynthesis for CO 2 reduction typically requires: photosensitizer, catalyst electron donor Products are CO, formate, and H 2 Co macrocycles Ni macrocycles Cobalt and Iron porphyrins, Phthalocyanines and corroles Ru(bpy) 2 (CO)X Re(bpy)(CO) 3 X Ni(bpy) 3 2+ charge separation h TEA TEA +
Key Achievements: Strategic Alliance and Collaboration with leaders at Brookhaven National Laboratory (Fujita) in Photocatalytic CO 2 reduction to develop catalysts for CO reduction in scCO 2 The promise of this new approach to CO 2 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 scCO 2 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 A few nanoseconds A 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 CO 2 Utilisation – future work