Effect of Controlled Deactivation on the Properties of a Supported Nickel Catalyst in the Reactions of Liquid-Phase Hydrogenation of Carbon–Carbon Multiple Bonds.

Afineevskii, A. V.; Prozorov, D. A.; Knyazev, A. V.; Nikitin, K. A.

The effect of controlled deactivation of Ni/SiO2 catalysts in the reactions of liquid-phase reduction of the carbon–carbon double bond in maleic acid diethyl ester (MADE) molecule was examined. The influence of the total quantity of deposited metal and of the quantity of reduced metal on the structural and mechanical, as well as the catalytic properties of nickel deposited on silica gel was studied. The effect produced by the surface sulfidation on the catalytic properties of the active metal as dependent on the percentage of the nickel oxide deposited was demonstrated. Practical absence of the relative structure sensitivity of the supported catalysts was experimentally proved. The relative structure sensitivity of the catalyst was calculated as the fractal dimension of the surface of the Ni°/SiO2 samples after one of the technological processes, related to that of the fresh nickel catalyst. The relative structure sensitivity of the catalyst surface as influenced by various hydrodynamic regimes, increased pressure, and nature of the solvent, as well as by adsorption of the reactants and the proceeding of the hydrogenation reactions and the deactivation process was considered. It was found that, during the synthesis process, the catalyst was saturated with hydrogen in the reactor, the reduction reaction of MADE proceeded, the catalyst was deactivation by the sulfide ion, and the catalyst surface underwent certain changes. Specifically, the surface roughness increased, and the sizes of the agglomerates and of the crystallites decreased. The influence of controlled partial deactivation of the nickel active sites by the sulfide ion on the activity of the supported catalysts was evaluated, and the ratios of the surface atoms of nickel, hydrogen, and sulfur in the catalytic systems possessing different activities were calculated. It was shown that, when the nickel catalyst surface was deactivated by the sulfide ions taken in a proportion of one sulfur atom per two surface nickel atoms, the activity of the catalyst was reduced by 90% and could not be subsequently restored.

NICKEL catalysts; CATALYSTS; CARBON-carbon bonds; CATALYST poisoning; CATALYST structure; DIETHYL sulfate; FRACTAL dimensions

Russian Journal of General Chemistry, 2021, Vol 91, Issue 12, p2613

1070-3632

Academic Journal

10.1134/S107036322112032X