Hydrogenation of C`'5 olefins in vapor phase on the copper oxide catalyst

Abstract

Hydrogenation of unsaturated hydrocarbons is one of the important processes of the modern petrochemical industry. Quite large amount of C4-5 fractions of hydrocarbons containing paraffins and olefins are formed via pyrolysis of light petroleum products. To increase the production of ethylene and propylene, the separated C4-5 fractions are recycled for pyrolysis. Preliminary hydrogenation of olefin compounds in these fractions is necessary. Preferably, the hydrogenation is carried out in the liquid phase at temperatures of 40 – 80 °C under hydrogen pressure up to 15 bar overhigh-cost palladium-containing catalysts. The aim of this work was to elucidate the possibility of efficient hydrogenation of industrial С5 fraction containing C`5 olefins over some mixed copper-oxide catalysts. Hydrogenation of C`5 fraction of pyrolysis of light petroleum products in the vapor phase over such catalysts as CuO-ZnO-ZrO2-Al2O3 and CuO-ZnOAl2O3 in comparison with commercial Pd/Al2O3 catalyst for C4-5 olefins hydrogenation have been studied. The pyrolysis C`5 fraction containing 51 wt. % of unsaturated hydrocarbons (2-methyl-1-butene, 2-pentene, cis-2-pentene, trans-2-pentene, 2-methyl-2-butene) was used in the work. The catalytic process was carried out in a reactor with a fixed catalyst bed at 170 – 190 oC, and a pressure of 1.1 – 2.5 MPa. Analysis of obtained products was provided by gas-chromatography (Agilent 7820A) and 13C NMR (Bruker Avance 400) methods. It is shown that the hydrogenation of olefins with conversion of the C`5 fraction such high as 98 – 99 % can be carried out in the vapor phase over CuO-ZnO-Al2O3 and CuO-ZnO-Al2O3 catalysts at the temperature of 180 oC and pressure 1.2 – 1.5 MPa. The total C5 olefinsloading can reach 15 – 23 mmol/gcat/h. The residual content of unsaturated hydrocarbons is 1 %. At the pressure of 2.5 MPa, a sharp decrease in conversion is observed, as n-pentane turns into a liquid phase. Catalyst deactivation was not observed for 36 hours. Under the same conditions the drop in activity of industrial catalyst 0.35 % Pd/Al2O3 was observed after 70 minutes from the start of work.