Acetylene Hydrogenation to Ethylene in a Hydrogen-Rich Gaseous Mixture on a Pd/Sibunit Catalyst

Abstract

The reaction of the gas-phase hydrogenation of acetylene on a Pd/Sibunit catalyst was studied depending on the H₂ : C₂H₂ molar ratio, the process temperature, and the presence of carbon monoxide. It was shown that for the reaction mixture of the composition H₂ : C₂H₂ < 20, the reaction rate depends on the hydrogen concentration and does not depend on the acetylene concentration, although for the ratio H₂ : C₂H₂ > 20, on the contrary, the order in hydrogen becomes zero and the reaction rate is determined by the acetylene content in the reaction mixture. It was found that an increase in the reaction temperature (from 30 to 85°C) leads to an increase in the contribution of complete hydrogenation to ethane. The introduction of CO into the reaction mixture up to a molar ratio of CO : C₂H₂ = 0.1 is accompanied by the almost complete blocking of the C₂H₄ readsorption sites, which results in a sharp increase in ethylene selectivity from 4 to 73%. With a further increase in the CO : C₂H₂ ratio, the number of sites available for hydrogen adsorption gradually decreases, and, correspondingly, the conversion decreases.