A KINETIC-MODEL FOR ALUMINA SULFATION

SO2 adsorption on alumina and sulfation with SO2 + O-2 have been inves tigated by IR spectroscopy and thermogravimetric measurements at tempe ratures quite similar to Claus process plant operating conditions (280 -350 degrees C), The sulfation was studied under various P(SO2) and P( O-2) pressures. The results allow a kinetic model for alumina sulfatio n to be proposed, The elementary steps of the mechanism involve two ty pes of surface site. The same site contributes to SO2 adsorption as su lfite and to sulfate formation. Another catalytic site leads to oxygen dissociation, On pure alumina the number of this last site is very lo w. The model enables the weight gain due to the fixation of SO2 and O- 2 to be expressed as a function of time, Kinetic constants were calcul ated from various sulfation experiments and the theoretical expression so obtained fits the experimental curves. (C) 1996 Academic Press, In c.