Pd/CeO2 catalysts are prepared via incipient wetness impregnation method for selective hydrogenation of acetylene in ethylene and evaluated at temperatures from 50°C to 200°C with a H2/C2H2/C2H4 ratio of 3/1/99 and a space velocity of 60,000 cc/h/g. The results show that catalysts with higher palladium loading have greater acetylene conversion than those with lower one. Since calcination temperature is one of the factors which can affect the activity and selectivity of the catalysts, various calcination temperatures are investigated in this study. With high calcination temperature, such as 600 and 800, the acetylene conversion of catalysts decreases and the ethylene selectivity increases. Effect of reduction at 250°C pretreatment is investigated as well. The results present that reduction procedure do enhance the activity of these catalyst. However, the selectivity decrease dramatically. Catalytic stability is studied under various temperatures, such as 86°C and 92°C and the catalysts show quite stable catalytic performance. To probe surface characteristics, catalysts are characterized by in-situ Fourier Transform Infrared Spectroscopy of CO adsorption before and after pretreatment procedures, including no reduction and combination of reduction and calcination. The results show that apparent cationic Pd species exist on the surface of catalysts without reduction. Cationic Pd could be reduced by CO during CO adsorption. The main Pd species is metal palladium after reduction. However, cationic Pd species still remain even after reduction at 250 °C. The characteristics of the catalysts are also measured using Atomic Absorption Spectroscopy and H2-chemisorption techniques. Catalyst characteristics will be compared and discussed with the reaction results.

Investigation of Pd/CeO2 catalysts for acetylene selective hydrogenation

255th National Meeting (2018)

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