CHEMISORPTION-CATALYTIC PROPERTIES OF ZINC OXIDE IN THE PROCESS OF REDUCTION OF PROPYL MERCAPTAN

Abstract

In this work, the adsorption and catalytic properties of zinc oxide, which it exhibits in the process of desulfurization of propyl mercaptan, are studied. It is shown that zinc oxide obtained by ammonia-carbonate technology has a specific surface area of 40.34 m2/g. Nitrogen adsorption-desorption isotherms refer to type IV according to the IUPAC classification, which is typical for mesoporous materials. The calculation of the pore size distribution shows that ZnO contains pores with a diameter of 2 to 40 nm. The characteristics of the chemisorption-catalytic activity of zinc oxide are given. It has been established that during the catalytic reduction of C3H7SH with hydrogen, the formation and absorption of H2S with the formation of zinc sulfide occur. In this case, depending on the time of operation, there is a gradual decrease in the average size of crystallites of the ZnO phase and an increase in the size of crystallites of the zinc sulfide phase. The study of catalytic activity in the hydrogenation reaction of propyl mercaptan with hydrogen was studied during the full cycle of ZnO operation at temperatures of 350 and 400 °C in a flow-type installation. The stages of the process of interaction of the components of the gas mixture (propyl mercaptan and hydrogen sulfide) with zinc oxide are revealed. It is shown that in the initial period of ZnO operation, intense absorption of hydrogen sulfide occurs with the formation of a zinc sulfide phase. The appearance of hydrogen sulfide at the outlet of the catalytic reactor is fixed after 100-200 min of operation. The second stage is characterized by a rapid increase in the concentration of hydrogen sulfide at the outlet of the catalytic reactor with a simultaneous decrease in the concentration of propyl mercaptan. The third stage occurs after 450-550 min of operation and is characterized by the constancy of the composition of the gas mixture at the outlet of the reactor.