The application of dry-oxide absorbents to the removal of sulphur dioxide from the gas was gaining considerable interest as compared to other processes which were wet or catalytic. This topical interest of the day led to the present research work. Copper oxide on alumina was used for acceptance of sulphur dioxide and was subsequently regenerated. Apart from some patents, little has boon published on the detailed examination of the reaction mechanisms of absorption and regeneration; hence the need for the present work. Absorption studies were carried out using mixtures of sulphur dioxide, oxygen and nitrogen. Hydrogen was used as a reducing agent to regenerate copper oxide on alumina from the copper sulphate formed. Experiments have been carried out in the temperature range of 270-500 °C, the range in which the kinetics and the extent of the reaction could be measured accurately. A mass flow balance and a thermobalance fitted with a differential thermal analyser were used for single pellet work. In order to investigate the kinetics of the intermediates in the reaction, a system was designed for incremental studies. The overall reaction for regeneration was found to be complex, CuSO4.A1203 + 4H2 = CuO.A1203 + 3H20 + H2 S. Activation energies and order of reaction with respect to both fluid and solid reactant concentrations were obtained. Throughout the operating temperature range, it was observed that regeneration reached a limiting value that increased with temperature. Chemically bound water in the alumina offers an explanation of this behaviour. For absorption studies of sulphur dioxide on alumina, activation energies and dependence on fluid reactant concentrations were obtained in the range 270-500 °C. The overall reaction is CuO.Al203 + CO2 + 1/2 02 = CuSO4-A1203. One notable feature in the sulphation process not considered by other workers is that sulphation of alumina occurs and will lead to cracking and attrition of the alumina carrier. In the existing fluid-solid reaction models, a new concept of core-diffusion control was introduced in the chemically controlled conditions. Also in the particle pellet model developed, a diffuse interface was assumed to exist in the particle as well as over the pellet as a whole. Other workers using the particle-pellet model have assumed that a sharp interface exists within the particle. This can restrict the model unnecessarily. Both isothermal and non-isothermal theories were considered, but the experimental work refers only to the isothermal because of the nature of the chemical reactions involved.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:639017 |
| Date | January 1978 |
| Creators | Sheikh, A. P. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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