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The catalytic decomposition of nitrous oxide

Richards, Nia 2019. The catalytic decomposition of nitrous oxide. PhD Thesis, Cardiff University.
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Abstract

N2O is an extremely potent greenhouse gas that has been shown to have devastating effects on the atmosphere. There are many natural and anthropogenic sources of N2O emissions, such as oceans, atmospheric chemical reactions, industrial chemical processes, by-product from fuel combustion, and contributions from the agricultural sector. Therefore a catalyst that converts N2O into N2 and O2 at low temperatures is highly desirable. Throughout this thesis the common aim is to produce a catalyst that can decompose N2O at temperatures lower than 300 °C. Three different classes of catalysts were investigated in this thesis, the first is a Fe-ZSM-5 catalyst. The work focusses on the effect of different Fe species in Fe-ZSM-5 for the decomposition of N2O in the presence and absence of a reductant, propane. The effect of Si:Al ratio and Fe weight loading was initially investigated before focussing on a single weight loading and the effects of acid washing on catalyst activity and iron speciation. The second class of catalysts were based on Pd-Al2O3 with the focus being on the importance of surface species and particle size of Pd for the decomposition of N2O. The effect of removal of surface species such as water and chloride ions were investigated by different catalyst pre-treatments and support pre-treatments. Through pre-treatment of the catalyst support prior to metal deposition, catalytic activity significantly increased, resulting in a decrease of the T100 by 150 °C to 400 °C. The third class of catalysts studied were a range of perovskite structured materials. Most notably studying how the surface area, phase purity and oxygen species present effected the catalytic activity. The factors were investigated by changing the ratio of elements in the A and B sites, which lead to increased perovskite purities requiring lower calcination temperatures leading to higher surface areas. The ratios that produced the highest phase purity were prepared by two alternative preparation method to the original citric acid preparation, supercritical anti-solvent preparation and oxalic acid preparation.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Date of First Compliant Deposit: 20 September 2019
Last Modified: 23 Sep 2019 10:39
URI: http://orca.cf.ac.uk/id/eprint/125568

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