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Type of Document	Dissertation
Author	Edelstein, Sergio
Author's Email Address	sergio@alumni.caltech.edu
URN	etd-05052006-082025
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-05052006-082025
Title	Adsorption of sulphur dioxide and reduction of sulphate on alumina and alkali-alumina at high temperatures
Degree	PhD
Option	Chemical Engineering
Advisory Committee	Advisor Name Title George R. Gavalas Committee Chair
Keywords	none
Date of Defense	1986-11-03
Availability	unrestricted
Abstract Several interrelated problems in connection with the treatment of sulfur dioxide at temperatures between 700 and 800°C were studied. The interaction of SO2 with Al2O3 was studied experimentally using B.E.T., thermogravimetry and temperature-programmed desorption. Adsorption takes place through a wide range of binding energies, with some SO2 adsorbing irreversibly at temperatures below 800°C. The amount adsorbed depends on the surface history and thermal treatment. An adsorption isotherm based on a bimodal energy distribution provides an adequate description of the equilibrium process. The chemical composition, sulfation and regeneration of an alkali-alumina sorbent for sulfur dioxide were studied using thermogravimetry, gas chromatography, and X-ray photoelectron spectroscopy. The active sorbent consists of a thin layer of sodium and lithium aluminates supported on alumina. The rate of sulfation is proportional to the SO2 concentration in the gas, up to [SO2] [approx.] 5000 ppm. The activation energy of the sulfation is E = 21.6 kcal/mole. The sulfated sorbent was regenerated by reduction with CO at 700-800°C. Sulfur removal from the sorbent and distribution of gaseous products were measured at different alkali loadings, temperatures and CO concentrations. The reduction takes place in two consecutive stages through a complex reaction network in which the alumina support plays a decisive role, both as a reactant and as a catalyst. A simplified reaction network is used as a basis for a kinetic model that provides an adequate description of the reduction process at moderate sorbent loadings.
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