Reactivity of Carbonyl Sulfide and Carbon Disulfide in Vapor-Phase Hydrolysis over Alumina Catalyst

Abstract

Vapor-phase hydrolysis of COS as well as CS, over alumina catalyst xhas been investigated at 230° C with reference to their relative reactivity. The overall relative reactivity, lecosKcos/kcs2. Kosgi where k, and K, are the surface reaction rate constant and the equilibrium adsorption constant for i species (COS or CS), respectively, has been determined to be 6.49 by the initial rate method whereas it to be 7.35 by means of the cohydrolysis of these sulfur compounds. In addition to these, an overall relative reactivity of 6.15 or 29.9 has been 'obtained front the mathematical analysis for the consecutive hydrolysis of CS, to CO, via COS. Since the relative eqUilibrium adsorption constant, Kcos/Kcs2, has been shown to be 2.7 from the inhibition effect of CO, on the hydrolysis reaction, the relative surface reaction rate constant, kcs/ks, , has been estimated to be 2.3-2.7, indicating the higher reactive nature of COS than CS₂; These methods used and the obtained results are discussed. An overall= relative reactivity, : of 6.15-, 4.49 and a relative surface reaction rate constant of 2.3-2.4 are shown to be reasonable values. It is also shown that the reactivity of the sulfur compounds is decisively influenced by the nature of the negatively charged adsorbed molecule as being active species for the surface reaction rather than by that of the free molecule.