12 results on '"Stevens, Lee A."'
Search Results
2. Determination of Pore Network Accessibility in Hierarchical Porous Solids.
- Author
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Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E. L., and Fletcher, Robin S.
- Published
- 2017
- Full Text
- View/download PDF
3. Formation of Metallurgical Coke within Minutes through Coal Densification and Microwave Energy.
- Author
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Williams, Orla, Ure, Alex, Stevens, Lee, Binner, Eleanor, Dodds, Chris, Kingman, Samuel, Das, Bidyut, Dash, Pratik Swarup, and Lester, Edward
- Published
- 2019
- Full Text
- View/download PDF
4. Swellable, Water- and Acid-Tolerant Polymer Sponges for Chemoselective Carbon Dioxide Capture
- Author
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Woodward, Robert T., Stevens, Lee A., Dawson, Robert, Vijayaraghavan, Meera, Hasell, Tom, Silverwood, Ian P., Ewing, Andrew V., Ratvijitvech, Thanchanok, Exley, Jason D., Chong, Samantha Y., Blanc, Frédéric, Adams, Dave J., Kazarian, Sergei G., Snape, Colin E., Drage, Trevor C., and Cooper, Andrew I.
- Subjects
- *
POLYMER research , *CARBON dioxide & the environment , *CARBON sequestration , *CHEMOSELECTIVITY , *ADSORPTION (Chemistry) , *METAL-organic frameworks , *SURFACE chemistry - Abstract
To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal—organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
5. Impact of Water Coadsorption for Carbon Dioxide Capture in Microporous Polymer Sorbents.
- Author
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Dawson, Robert, Stevens, Lee A., Drage, Trevor C., Snape, Colin E., Smith, Martin W., Adams, Dave J., and Cooper, Andrew I.
- Subjects
- *
POLYMER networks , *BINAPHTHOL , *FRIEDEL-Crafts reaction , *CARBON sequestration , *SORBENT testing , *MICROPOROSITY - Abstract
Alcohol-containing polymer networks synthesized by Friedel-Crafts alkylation have surface areas of up to 1015 m2/g. Both racemic and chiral microporous binaphthol (BINOL) networks can be produced by a simple, one-step route. The BINOL networks show higher CO2 capture capacities than their naphthol counterparts under idealized, dry conditions. In the presence of water vapor, however, these BINOL networks adsorb less CO2 than more hydrophobic analogues, suggesting that idealized measurements may give a poor indication of performance under more realistic carbon capture conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
6. Determination of pore network accessibility in hierarchical porous solids
- Author
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Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., Fletcher, Robin S., Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., and Fletcher, Robin S.
- Abstract
This paper validates the hypothesis that the supposedly non-specific adsorbates nitrogen and argon wet heavy metals differently, and shows how this unexpected effect can be actively utilised to deliver information on pore inter-connectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica-alumina material were compared with data for pure silica and alumina materials. The new structural characterisation described can determine the distribution of the particular sub-set of meso-and micro-pores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerised X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica-alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the new method has been independently validated using complementary gas sorption scanning curves, integrated mercury porosimetry, and NMR cryoporometry. It has also been shown that, rather than hindering interpretation of characterisation data, emergent effects for networks associated with these techniques can be marshalled to enable detailed assessment of the pore structures of complex, disordered solids.
- Full Text
- View/download PDF
7. Determination of pore network accessibility in hierarchical porous solids
- Author
-
Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., Fletcher, Robin S., Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., and Fletcher, Robin S.
- Abstract
This paper validates the hypothesis that the supposedly non-specific adsorbates nitrogen and argon wet heavy metals differently, and shows how this unexpected effect can be actively utilised to deliver information on pore inter-connectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica-alumina material were compared with data for pure silica and alumina materials. The new structural characterisation described can determine the distribution of the particular sub-set of meso-and micro-pores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerised X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica-alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the new method has been independently validated using complementary gas sorption scanning curves, integrated mercury porosimetry, and NMR cryoporometry. It has also been shown that, rather than hindering interpretation of characterisation data, emergent effects for networks associated with these techniques can be marshalled to enable detailed assessment of the pore structures of complex, disordered solids.
- Full Text
- View/download PDF
8. Determination of pore network accessibility in hierarchical porous solids
- Author
-
Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., Fletcher, Robin S., Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., and Fletcher, Robin S.
- Abstract
This paper validates the hypothesis that the supposedly non-specific adsorbates nitrogen and argon wet heavy metals differently, and shows how this unexpected effect can be actively utilised to deliver information on pore inter-connectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica-alumina material were compared with data for pure silica and alumina materials. The new structural characterisation described can determine the distribution of the particular sub-set of meso-and micro-pores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerised X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica-alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the new method has been independently validated using complementary gas sorption scanning curves, integrated mercury porosimetry, and NMR cryoporometry. It has also been shown that, rather than hindering interpretation of characterisation data, emergent effects for networks associated with these techniques can be marshalled to enable detailed assessment of the pore structures of complex, disordered solids.
- Full Text
- View/download PDF
9. Determination of pore network accessibility in hierarchical porous solids
- Author
-
Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., Fletcher, Robin S., Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., and Fletcher, Robin S.
- Abstract
This paper validates the hypothesis that the supposedly non-specific adsorbates nitrogen and argon wet heavy metals differently, and shows how this unexpected effect can be actively utilised to deliver information on pore inter-connectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica-alumina material were compared with data for pure silica and alumina materials. The new structural characterisation described can determine the distribution of the particular sub-set of meso-and micro-pores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerised X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica-alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the new method has been independently validated using complementary gas sorption scanning curves, integrated mercury porosimetry, and NMR cryoporometry. It has also been shown that, rather than hindering interpretation of characterisation data, emergent effects for networks associated with these techniques can be marshalled to enable detailed assessment of the pore structures of complex, disordered solids.
- Full Text
- View/download PDF
10. Determination of pore network accessibility in hierarchical porous solids
- Author
-
Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., Fletcher, Robin S., Rigby, Sean P., Hasan, Muayad, Stevens, Lee, Williams, Huw E.L., and Fletcher, Robin S.
- Abstract
This paper validates the hypothesis that the supposedly non-specific adsorbates nitrogen and argon wet heavy metals differently, and shows how this unexpected effect can be actively utilised to deliver information on pore inter-connectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica-alumina material were compared with data for pure silica and alumina materials. The new structural characterisation described can determine the distribution of the particular sub-set of meso-and micro-pores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerised X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica-alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the new method has been independently validated using complementary gas sorption scanning curves, integrated mercury porosimetry, and NMR cryoporometry. It has also been shown that, rather than hindering interpretation of characterisation data, emergent effects for networks associated with these techniques can be marshalled to enable detailed assessment of the pore structures of complex, disordered solids.
- Full Text
- View/download PDF
11. Correction to "Ni Mg Mixed Metal Oxides for p-Type Dye-Sensitized Solar Cells".
- Author
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Zannotti M, Wood CJ, Summers GH, Stevens LA, Hall MR, Snape CE, Giovannetti R, and Gibson EA
- Published
- 2015
- Full Text
- View/download PDF
12. Ni Mg Mixed Metal Oxides for p-Type Dye-Sensitized Solar Cells.
- Author
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Zannotti M, Wood CJ, Summers GH, Stevens LA, Hall MR, Snape CE, Giovannetti R, and Gibson EA
- Abstract
Mg Ni mixed metal oxide photocathodes have been prepared by a mixed NiCl2/MgCl2 sol-gel process. The MgO/NiO electrodes have been extensively characterized using physical and electrochemical methods. Dye-sensitized solar cells have been prepared from these films, and the higher concentrations of MgO improved the photovoltage of these devices; however, there was a notable drop in photocurrent with increasing Mg(2+). Charge extraction and XPS experiments revealed that the cause of this was a positive shift in the energy of the valence band, which decreased the driving force for electron transfer from the NiO film to the dye and, therefore, the photocurrent. In addition, increasing concentrations of MgO increases the volume of pores between 0.500 and 0.050 μm, while reducing pore volumes in the mesopore range (less than 0.050 μm) and lowering BET surface area from approximately 41 down to 30 m(2) g(-1). A MgO concentration of 5% was found to strike a balance between the increased photovoltage and decreased photocurrent, possessing a BET surface area of 35 m(2) g(-1) and a large pore volume in both the meso- and macropore range, which lead to a higher overall power conversion efficiency than NiO alone.
- Published
- 2015
- Full Text
- View/download PDF
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