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Design of Catalysts for the Abatement or Decomposition of Anthropogenic Carbon Dioxide Methane and Nitrous Oxide.

Ahmed, Faruk. (2004) Design of Catalysts for the Abatement or Decomposition of Anthropogenic Carbon Dioxide Methane and Nitrous Oxide. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are major greenhouse gases (GHG). The aim of this research was to develop improved catalysts for CO2-CH4 reactions and N2O decomposition via sol gel (SG) routes. 0.5 wt % Rh/Ti02 (SG) was prepared and found to be effective for the decomposition of N2O. This served the purpose of removing atmospheric N2O and decomposing this green mono-propellant for satellite microthrusters; where it could also be a competitor of commercial Shell 405 (36 wt. % Ir/Al2O3) catalysts. The CO2-CH4 reaction was studied in a temperature-programmed (TP) mode. In the a region there appeared to be no reaction occurring but during the B region the full catalytic reaction was observed. Interestingly, pulses of CO2 produced little O. However, CH4 pulses produced both H and CHx. In steady state catalysis the ratio of reactant consumption (CO2/CH4) was generally 1:1. Almost all catalysts considered here produced CO and H2 only during the CH4 pulse. Heterogeneous photocatalysis of dry reforming of CH4 and decomposition of N2O on present catalyst surfaces was shown to be possible. Materials were characterised before and after use with a range of analytical techniques including Fourier transform infrared (FT-IR) spectroscopy with CO, Raman spectroscopy, X-ray diffraction (XRD), Brunauer Emmett & Teller (BET) physisorption, scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy (XPS). These techniques showed that the unused pre-calcined (773 K) catalyst surface was clean from organic species, but that in dry reforming there was an accumulation of carbonaceous species (as seen above) on the used surface. Furthermore turnover frequency (TOF) for ceramic foam (CF) catalyst was found to be as good as Shell 405 (see Chapter 7). The keynote finding was that catalyts can be designed and used to reduce the environmental impact of GHG emissions and provide routes to other commercial processes.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Ahmed, Faruk.
Date : 2004
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2004.
Depositing User : EPrints Services
Date Deposited : 30 Apr 2019 08:08
Last Modified : 20 Aug 2019 15:33
URI: http://epubs.surrey.ac.uk/id/eprint/851643

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