Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440527
Title: Electrochemical recovery of platinum and palladium from alumina supported catalysts
Author: Dawson, Richard James
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2006
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Abstract:
The process dissolves Pt and Pd selectively from catalysts in a leach reactor, using an oxidant (I3-) and complement (I-), the reduced form of the oxidant. The precious metals are then electrodeposited on the cathode of an electrochemical reactor, incorporating a cation-permeable membrane, to enable the oxidant to be regenerated simultaneously at the anode without its subsequent reduction at the cathode. The iodide system was identified as being able to dissolve Pt and Pd, using tri-iodide as oxidant, at neutral pH to minimise alumina dissolution rates. The reaction kinetics were determined using techniques, such as voltammetry with rotating disc electrodes. Micro-kinetic models were developed for the oxidant reduction and metal oxidation processes, so that the behaviour of leaching metal could be predicted quantitatively under the different conditions used. As only low concentration leach solutions were produced, a cathode with high specific surface area and high mass transport rates was required to achieve acceptable capital and running costs of the electrochemical reactor. This was achieved with a cathode plate contacting a circulating bed of sub-mm graphite particles, on which adherent/coherent electrodeposits were grown. The electrical operation of the reactor was modelled successfully to give good agreement with the experimental data. Low specific electrical energy consumptions of < 1 kWh kg⁻¹ Pt were reported for the reactor. The feasibility of the overall process has been demonstrated and the running cost, of ca. £0.63 kg-1 of catalyst, calculated for the laboratory scale plant built, was significantly lower than the target set by Johnson Matthey Plc. However, for the spent catalyst sample investigated, the absolute recovery of Pt has been found to be limited to only ca. 90%, probably because of physical encapsulation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.440527  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General)
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