KINETICS OF 2-CHLORO-4-NITROANILINE HYDROGENATION OVER SUPPORTED PLATINUM AND PALLADIUM CATALYSTS IN WATER SOLUTION OF 2-PROPANOL

The kinetics of liquid-phase hydrogenation of 2-chloro-4-nitroaniline over supported platinum and palladium catalysts in the aqueous solution of 2-propanol (0.68 mole fraction) was studied. Dependences of changes in concentration of participants vs the reaction time was obtained. The orders of reaction with respect to hydrogen and initial reagent were zero and the first. The palladium catalysts in comparison with platinum catalysts absorbed more amount of hydrogen. The products of dehalogenation reaction are main by-products. The platinum catalysts, as rules, more active in the conversion of the nitro group and selective with respect to chloroamine. The chloroaniline hydrogenation over the studied catalysts proceeded on sequential scheme. So, the chloroamine was dehalogenated. The values of the rate constants for all catalyst samples were varied depending on the total metal content. It was found that low-percentage platinum catalysts allow to achieve high selectivity of hydrogenation of HNC with respect to CFDA while maintaining the values of the observed rates of hydrogen absorption the similar as palladium catalysts. It is known that the kinetic regularities of catalytic reactions are associated with the structural and physicochemical characteristics of the catalysts. In particular, palladium and platinum have different electronic structures and behave is different in the catalytic reaction. Structure characteristics have value for the reaction kinetics also. The obtained data are consistent with these facts. However, some assumption appeared, that when the nature of the solvent varies, the same catalyst can behave differently. So, determination the relationship between the structure and activity of the catalyst only is not sufficiently correct for liquid-phase systems, without including the effect of the nature of the solvent.Forcitation:Latypova A.R., Krasnov A.I., Sharonov N.Yu., Safarov I.M., Lefedova O.V. Kinetics of 2-chloro-4-nitroaniline hydrogenation over supported platinum and palladium catalysts in water solution of 2-propanol. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 42-48