Co-reporter:H. Gu;J. S. J. Hargreaves;J. -Q. Jiang;J. L. Rico
Journal of Sustainable Metallurgy 2017 Volume 3( Issue 3) pp:561-569
Publication Date(Web):21 December 2016
DOI:10.1007/s40831-016-0112-2
Red mud, an aluminum industry large-scale waste, was used as a precursor to prepare sodium ferrate(VI) and sodium ferrite following different reaction pathways. Ferrous oxalate extracted from red mud has been used as an intermediate for the preparation of these compounds. The conversion rate to sodium ferrate(VI) from ferrous oxalate was as high as 64% in sodium hydroxide solution with sodium hypochlorite. Furthermore, sodium ferrite was formed after performing the solid–solid reaction at 600 °C using a 1:1 weight ratio of iron oxide (prepared via the ferrous oxalate extraction route from red mud) and sodium peroxide. In contrast, sodium iron silicon oxides were formed when red mud was reacted directly, following similar experimental procedures. These results present an interesting alternative to convert an environmentally unfriendly waste to new value-added products. It is envisaged that sodium ferrate(VI) might be of great interest in terms of wastewater treatment, whereas sodium ferrite and NawFexSiyOz might be of interest in the development of new materials for energy storage.
Co-reporter:J. L. Rico;J. S. J. Hargreaves
Journal of Materials Science 2017 Volume 52( Issue 9) pp:5188-5193
Publication Date(Web):19 January 2017
DOI:10.1007/s10853-017-0759-5
With the aim to obtain iron tubular microstructures attractive for various applications, we have used a natural biogenic iron ochre as a raw material and explore various procedures and experimental conditions to achieve our goal. Our experiments included reduction, nitridation and characterization of microtubes derived from biogenic iron ochre. Various temperatures of reduction under streams of H2/N2 or NH3 were tested. Our results show that the tubular structure is maintained after reduction of the natural material under H2/N2. In addition, ammonia was not produced under our experimental conditions, and as expected, hydrogen reduced the material. However, the treatment under NH3 reduces the material and allows the incorporation of nitrogen into the structure of the solid yielding iron nitride microtubes. Reduced and nitrided microstructures were successfully obtained from natural biogenic iron ochre. A temperature of 500 °C seems to be suitable to expose the calcined biogenic iron ochre under H2/N2 for 4 h or under ammonia for 8 h to obtain reduced or nitrided microtubes, respectively. The stability of the tubular structure during reduction/reduction–nitridation is maintained under both treatments. Further interesting applications of this natural biomaterial could be envisaged.
Co-reporter:Ihfaf AlShibane;Justin S. J. Hargreaves;Andrew L. Hector;William Levason;Andrew McFarlane
Dalton Transactions 2017 vol. 46(Issue 27) pp:8782-8787
Publication Date(Web):2017/07/11
DOI:10.1039/C7DT00285H
The co-ammonolysis of V(NMe2)4 and Si(NHMe)4 with ammonia in THF and in the presence of ammonium triflate ([NH4][CF3SO3]) leads to the formation of monolithic gels. Pyrolysing these gels produces mesoporous composite materials containing nanocrystalline VN and amorphous silicon imidonitride. Elemental mapping indicated a thorough distribution of VN with no evidence of large cluster segregation. Whilst not active for ammonia synthesis, the silicon nitride based materials were found to possess activity for the COx-free production of H2 from methane, which makes them candidates for applications in which the presence of low levels of CO in H2 feedstreams is detrimental.
Co-reporter:Nicholas A. Spencer, Evert J. Ditzel, Justin S. J. Hargreaves and Stephen Sproules
Journal of Materials Chemistry A 2016 vol. 4(Issue 18) pp:7036-7044
Publication Date(Web):23 Mar 2016
DOI:10.1039/C6TA01053A
It is shown that control of the degree of coking can lead to the observation of hyperfine structures in the carbonaceous residues deposited from methanol over mordenite (H-MOR) at temperatures relevant to the conversion of methanol to hydrocarbons. EPR measurements of the catalyst samples at various times on stream have been recorded, with a rich hyperfine splitting pattern observed in the early stages of the reaction. Interpretation of the EPR data with the aid of density functional theoretical calculations has afforded the first definitive assignment of the radical cations formed in high temperature coke. The results detail a shortlist of six species: 2,3/2,6/2,7-dimethylnaphthalenium, 2,3,6-trimethylnaphthalenium, 2,3,6,7-tetramethylnaphthalenium, and anthracenium radical cations whose proton hyperfine splitting profiles match the experimental spectra; 2,3,6,7-tetramethylnaphthalenium showed the best agreement. The observation of these particular isomers of polymethylnaphthalene suggest the formation of more highly branched polyaromatic species is less likely within the confines of the H-MOR 12-membered ring channel. These radicals formed when the catalyst is active may constitute key intermediates in the conversion of methanol to light olefins.
Co-reporter:Hannian Gu, Justin S. J. Hargreaves, Andrew R. McFarlane and Gillian MacKinnon
RSC Advances 2016 vol. 6(Issue 52) pp:46421-46426
Publication Date(Web):26 Apr 2016
DOI:10.1039/C6RA06204K
Magnetic carbon materials were prepared by the catalytic growth of graphitic carbon and carbon nanofibers using methanol as a carbon source with a series of different red mud wastes. Both the raw red mud samples and the products were characterized using powder X-ray diffraction, scanning electron microscopy, Raman spectroscopy, Brunaeur Emmett and Teller surface area analysis, thermogravimetric analysis and carbon content analysis. Hematite and goethite in high iron content red muds were reduced into magnetite in 10 minutes at 500 °C, and graphitic carbon reflections were evident in the resultant powder X-ray diffraction pattern. Thus, the samples become magnetic and change color from red to black. After six hours reaction at 500 °C, the carbon content of the composite based on a high iron content Bayer process derived red mud reached as high as ca. 72% and its surface area increased from 17 to 312 m2 g−1.
Co-reporter:A. I. Alharthi;J. S. J. Hargreaves;I. D. Pulford
Journal of Sustainable Metallurgy 2016 Volume 2( Issue 4) pp:387-393
Publication Date(Web):2016 December
DOI:10.1007/s40831-016-0082-4
The aluminum industry generates large quantities of red mud during the beneficiation of bauxite ore. The red mud is disposed of as a waste in dry or wet form. Given the issues with its disposal due to the large volume and high alkalinity, many research groups and industries have examined the use of red mud for different applications. The use of red mud as a pre-catalyst for the cracking of hydrocarbon leads to hydrogen formation and carbon deposition. Our earlier studies have shown its activity for reaction with methane and the formation of magnetic materials containing iron, iron carbide, and nanocarbon species. In this study, two aspects were studied: one was methane cracking over red mud, modified red mud, and waste from a nailwork factory site and the other was the application of different hydrocarbons, including nitrogen-containing precursors over red mud. Preliminary characterization of the resulting carbon deposits was performed. The activity for methane cracking increased when the red mud was activated and reduced before the reaction. Nitrogen-containing reactants led to the formation of nitrogen-doped carbon nanotubes. The nitrogen amount and morphology varied with the precursor used and the reaction temperature. This is an attractive application with potential for further modification of the carbon deposits for other catalytic and electrochemical applications.
Co-reporter:Abdulrahman Alharthi;Ross A. Blackley;T. Hugh Flowers;Justin S. J. Hargreaves;Ian D. Pulford;James Wigzell;Wuzong Zhou
Journal of Chemical Technology and Biotechnology 2014 Volume 89( Issue 9) pp:1317-1323
Publication Date(Web):
DOI:10.1002/jctb.4434
Abstract
BACKGROUND
Iron ochres are gelatinous sludges that can cause problems in terms of water management. In this work, the application of iron ochre obtained from a river has been applied to catalytically crack methane – another potential waste product – into two useful products, hydrogen and a magnetic carbon-containing composite.
RESULTS
The powder X-ray diffraction (XRD) pattern of the iron ochre was found to be consistent with the expected 2-line ferrihydrite, and energy dispersive X-ray (EDX) analysis showed Fe to be a major component although some Si and Ca were present. The sample was observed to contain a fraction with a tubular morphology consistent with the presence of extra-cellular biogenic iron oxide formed by leptothrix. Upon exposure to methane at elevated temperatures, the material was found to transform into an active catalyst for hydrogen production yielding a magnetic carbon-containing composite material comprising filamentous carbon and encapsulating graphite.
CONCLUSION
The application of two waste products – iron ochre and methane – to generate two useful products – hydrogen and a magnetic carbon-containing composite – has been demonstrated. Furthermore, the ochre has been shown to comprise tubular morphology extra-cellular biogenic iron oxide which may be of interest in terms of other applications. © 2014 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Co-reporter:J. S. J. Hargreaves
Applied Petrochemical Research 2014 Volume 4( Issue 1) pp:3-10
Publication Date(Web):2014 May
DOI:10.1007/s13203-014-0049-y
In this article, an overview of the application of selected metal nitrides as ammonia synthesis catalysts is presented. The potential development of some systems into nitrogen transfer reagents is also described.
Co-reporter:J.S.J. Hargreaves
Coordination Chemistry Reviews 2013 Volume 257(13–14) pp:2015-2031
Publication Date(Web):July 2013
DOI:10.1016/j.ccr.2012.10.005
Metal nitrides are of interest as heterogeneous catalysts. In this review, the various methods by which nitrides of potential catalytic importance can be prepared are described, along with literature reports of the catalytic activity of nitrides for different reaction processes. It is clear that nitrides possess unique and interesting properties and in some cases small scale testing has indicated that activities of industrial significance could be achieved for some reactions. Exciting developments in heterogeneous catalysis with metal nitride based materials can be anticipated. Advances in synthesis will lead to improved understanding of structure–activity relationships through the preparation of materials with controlled and well-defined morphology. This will guide further catalyst development, as will access to materials with controllable more complex composition.Highlights► Versatility of preparation routes in controlling surface area, morphology and composition of metal nitrides. ► Application of metal nitrides to reactions of industrial significance. ► Structure–function relationships.
Co-reporter:J. S. J. Hargreaves and A. L. Munnoch
Catalysis Science & Technology 2013 vol. 3(Issue 5) pp:1165-1171
Publication Date(Web):04 Feb 2013
DOI:10.1039/C3CY20866D
By means of selected examples taken from the zeolite and zeotype academic literature, the influence of binders and matrix components upon the performance of heterogeneous catalysts is illustrated. Such effects can be significant, showing that the binders and matrices are far from inert components in many systems and that, accordingly, their role is worthy of greater consideration than has hitherto been the case.
Co-reporter:M. AlShalwi, J.S.J. Hargreaves, J.J. Liggat, D. Todd
Materials Research Bulletin 2012 47(5) pp: 1251-1256
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.01.022
Co-reporter:A.-M. Alexander;J. S. J. Hargreaves;C. Mitchell
Topics in Catalysis 2012 Volume 55( Issue 14-15) pp:1046-1053
Publication Date(Web):2012 October
DOI:10.1007/s11244-012-9890-3
Metal nitrides may be of interest as potential sources of activated nitrogen which can be reacted with target organic molecules. Accordingly, the reduction of nitrogen within Ni3N, Cu3N, Zn3N2 and Ta3N5 under a 1/3 Ar/H2 flow at elevated temperature has been determined as a simple test of lattice nitrogen reactivity. As anticipated by consideration of their stability, Ni3N and Cu3N are reduced completely at 250 °C with up to 30 % of their total lattice nitrogen yielding ammonia. The elimination of N2 results in the formation of pores which are particularly pronounced in the case of the denitrided Cu system. In the case of Zn3N2, the lattice nitrogen is less reactive with incomplete denitridation being observed at 400 °C and the amount of ammonia produced being 15 % of the total nitrogen available. Although Ta3N5 contains the least reactive nitrogen of the four samples studied, it can be regenerated by ammonolysis which is an important consideration in any envisaged application.
Co-reporter:J. S. J. Hargreaves
Topics in Catalysis 2012 Volume 55( Issue 14-15) pp:909
Publication Date(Web):2012 October
DOI:10.1007/s11244-012-9879-y
Co-reporter:L. J. France, D. C. Apperley, E. J. Ditzel, J. S. J. Hargreaves, J. P. Lewicki, J. J. Liggat and D. Todd
Catalysis Science & Technology 2011 vol. 1(Issue 6) pp:932-939
Publication Date(Web):07 Jun 2011
DOI:10.1039/C1CY00103E
An investigation of the nature of the carbonaceous species deposited upon mordenite by reaction with methanol has been undertaken. The nature of the species has been shown to be a strong function of both temperature and time on stream. Upon reaction at 300 °C a range of alkyl and aromatic species, consistent with the development of an active hydrocarbon pool, are evident and time on stream studies have shown that these are developed within 5 min. Upon reaction at 500 °C, a narrower range of hydrogen deficient aromatic species is evident. Thermal volatilisation analysis (TVA), not previously applied to the study of coked zeolites, is shown to be complementary to the more commonly applied C analysis, 13C MAS NMR and TGA techniques.
Co-reporter:Nicholas A. Spencer, Evert J. Ditzel, Justin S. J. Hargreaves and Stephen Sproules
Journal of Materials Chemistry A 2016 - vol. 4(Issue 18) pp:NaN7044-7044
Publication Date(Web):2016/03/23
DOI:10.1039/C6TA01053A
It is shown that control of the degree of coking can lead to the observation of hyperfine structures in the carbonaceous residues deposited from methanol over mordenite (H-MOR) at temperatures relevant to the conversion of methanol to hydrocarbons. EPR measurements of the catalyst samples at various times on stream have been recorded, with a rich hyperfine splitting pattern observed in the early stages of the reaction. Interpretation of the EPR data with the aid of density functional theoretical calculations has afforded the first definitive assignment of the radical cations formed in high temperature coke. The results detail a shortlist of six species: 2,3/2,6/2,7-dimethylnaphthalenium, 2,3,6-trimethylnaphthalenium, 2,3,6,7-tetramethylnaphthalenium, and anthracenium radical cations whose proton hyperfine splitting profiles match the experimental spectra; 2,3,6,7-tetramethylnaphthalenium showed the best agreement. The observation of these particular isomers of polymethylnaphthalene suggest the formation of more highly branched polyaromatic species is less likely within the confines of the H-MOR 12-membered ring channel. These radicals formed when the catalyst is active may constitute key intermediates in the conversion of methanol to light olefins.
Co-reporter:L. J. France, D. C. Apperley, E. J. Ditzel, J. S. J. Hargreaves, J. P. Lewicki, J. J. Liggat and D. Todd
Catalysis Science & Technology (2011-Present) 2011 - vol. 1(Issue 6) pp:NaN939-939
Publication Date(Web):2011/06/07
DOI:10.1039/C1CY00103E
An investigation of the nature of the carbonaceous species deposited upon mordenite by reaction with methanol has been undertaken. The nature of the species has been shown to be a strong function of both temperature and time on stream. Upon reaction at 300 °C a range of alkyl and aromatic species, consistent with the development of an active hydrocarbon pool, are evident and time on stream studies have shown that these are developed within 5 min. Upon reaction at 500 °C, a narrower range of hydrogen deficient aromatic species is evident. Thermal volatilisation analysis (TVA), not previously applied to the study of coked zeolites, is shown to be complementary to the more commonly applied C analysis, 13C MAS NMR and TGA techniques.
Co-reporter:J. S. J. Hargreaves and A. L. Munnoch
Catalysis Science & Technology (2011-Present) 2013 - vol. 3(Issue 5) pp:NaN1171-1171
Publication Date(Web):2013/02/04
DOI:10.1039/C3CY20866D
By means of selected examples taken from the zeolite and zeotype academic literature, the influence of binders and matrix components upon the performance of heterogeneous catalysts is illustrated. Such effects can be significant, showing that the binders and matrices are far from inert components in many systems and that, accordingly, their role is worthy of greater consideration than has hitherto been the case.
Co-reporter:Ihfaf AlShibane, Justin S. J. Hargreaves, Andrew L. Hector, William Levason and Andrew McFarlane
Dalton Transactions 2017 - vol. 46(Issue 27) pp:NaN8787-8787
Publication Date(Web):2017/02/27
DOI:10.1039/C7DT00285H
The co-ammonolysis of V(NMe2)4 and Si(NHMe)4 with ammonia in THF and in the presence of ammonium triflate ([NH4][CF3SO3]) leads to the formation of monolithic gels. Pyrolysing these gels produces mesoporous composite materials containing nanocrystalline VN and amorphous silicon imidonitride. Elemental mapping indicated a thorough distribution of VN with no evidence of large cluster segregation. Whilst not active for ammonia synthesis, the silicon nitride based materials were found to possess activity for the COx-free production of H2 from methane, which makes them candidates for applications in which the presence of low levels of CO in H2 feedstreams is detrimental.
