University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Tailored synthetic silicates for deNOx catalysis.

Roberts, Alexander John. (2003) Tailored synthetic silicates for deNOx catalysis. Doctoral thesis, University of Surrey (United Kingdom)..

Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (35MB) | Preview


Laponite synthetic clay has been modified via exchange with "A112M7+" (M = Al, Ga, Fe or In) pillaring species and further exchanged after calcination with various metal species. The chemically tailored materials produced have been characterised using powder XRD, thermal analysis, N2 sorption at 77 K, FT-IR and MAS-NMR spectroscopies. Preliminary testing as to their suitability as deNOx catalysts has been carried out both through direct catalytic testing and in-situ FT-IR spectroscopy with NO sorbate. The pillaring species themselves were also investigated through precipitation of their sulphates and characterisation by powder XRD, as synthesised and after heating to 1150&amp;deg;C, thermal analysis and FT-IR and MAS-NMR spectroscopies. None of the "A112M7+ Keggin sulphates" (M = Al, Ga, Fe or In) were single phase materials, all containing the A1137+ Keggin sulphate and at least one other phase. The successful exchange and pillaring of the Laponite parent clay was demonstrated through 27Al MAS-NMR by the observation the of resonance assigned to tetrahedral AlO4. 29Si MAS-NMR showed the presence of both Q3 layer and Q2 edge Si sites and the emergence of a resonance corresponding to Q3 (1OH) Si sites upon exchange of the parent clay. Heating the exchanged material resulted in the disappearance of this resonance, but a further resonance was observed corresponding to Q4(1Al) Si sites, further confirming a successful pillaring reaction. N2 sorption at 77 K gave isotherms consistent with the presence of both micropores and mesopores and specific surface areas in the range 260 m2g-1<SBET<360 m2g-1, with Kelvin pore diameters between 35 and 39 A. Upon heating the exchanged clays, no major change in the specific surface area was observed up to 600 &amp;deg;C, with the Kelvin pore diameter reaching a maximum at 400 &amp;deg;C but maintaining at least its original value up to 700 &amp;deg;C. In-situ FT-IR spectroscopy of Co2+-exchanged "A112Fe7+" Laponite in the presence of NO revealed a number of surface species (most notably nitrates, N2O and NO2) and suggestions have been made as to their route of formation. Catalytic testing of a range of materials for N2O destruction in both the presence and absence of CH4 showed a number to achieve 100 % conversion at low reactant flow rates, with the V-exchanged A1137+ Laponite showing the highest potential as a deN2O catalyst.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Roberts, Alexander John.
Date : 2003
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:13
Last Modified : 16 Mar 2018 13:26

Actions (login required)

View Item View Item


Downloads per month over past year

Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800