Study of carbon contamination in Solid Oxide Cells

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Title: Study of carbon contamination in Solid Oxide Cells
Authors: Duboviks, Vladislavs
Item Type: Thesis or dissertation
Abstract: An attractive application for the solid oxide cell (SOC) technology is to enable reversible energy conversion. SOCs can efficiently convert chemical energy into electricity. Equally, SOCs can utilise electrical energy to upgrade low energy fuels into higher energy mixtures. A key step in the development of the reversible SOC is mitigating carbon deposition to allow stable long term operation in the presence of hydrocarbons. The work presented in this thesis describes comprehensive analysis of the performance of current state-of-the-art materials followed by the development of a copper-based electrode with both technologically relevant performance and no carbon formation during electrolysis of CO2 in the presence of methane. For current state-of-the-art nickel materials, positive bias was found to suppress carbon deposits in pure CO, while negative bias facilitated cell degradation through increased carbon formation and subsequent electrode delamination. In situ and ex situ Raman analysis of the conventional cermet Ni/Gd0.1Ce0.9O2-δ (Ni/CGO) electrodes revealed differences in amount, location and type of carbon formed during CO – CO2 electrolysis. The rate of carbon deposition was also greatly increased in the presence of H2. The positive effect of a CGO interlayer on reducing carbon formation for nickel was demonstrated. Building upon the result of the conventional electrodes’ testing, a new batch of electrodes was prepared through a low temperature metal infiltration technique. Low temperature processing allowed Cu/CGO electrodes to be fabricated, which are difficult to produce with conventional techniques because of the low melting point of copper. It was demonstrated that the electrochemical performance of Cu/CGO electrodes is equivalent to Ni/CGO electrodes, whilst carbon formation is fully suppressed. This observation suggests that the electrocatalytic activity of these electrodes is dependent on CGO rather than metal (Cu or Ni), and moreover that the electrodes are ideally suited to biogas upgrade applications without deleterious carbon deposition.
Content Version: Open Access
Issue Date: Nov-2014
Date Awarded: Mar-2015
Supervisor: Offer, Gregory
Sponsor/Funder: Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/I00422X/1
Department: Earth Science & Engineering
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Earth Science and Engineering PhD theses

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