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Ethylene Epoxidation on Ag-Cs/α-Al 2 O 3 Catalyst: Experimental Results and Strategy for Kinetic Parameter Determination

2000; American Chemical Society; Volume: 39; Issue: 7 Linguagem: Inglês

10.1021/ie990939x

1520-5045

D. Lafarga, Mohammed Al-Juaied, Christina M. Bondy, Arvind Varma,

Catalysis and Hydrodesulfurization Studies

The kinetics of ethylene epoxidation network were studied experimentally over a cesium-doped silver catalyst supported on α-Al2O3 pellets in a differential reactor. A variety of rate functions were considered and among these, expressions based on a dual-site Langmuir−Hinselwood mechanism: ri = kiPE /(1 + PE)2, fitted the data best with an average error of 13.0 and 10.7% for the epoxidation and the complete combustion reactions, respectively. Under the experimental conditions, both reactants influence both reaction rates; however, product influence is negligible because of their small partial pressures present in the reactor. High oxygen/ethylene ratios and lower temperature favored selectivity to the epoxidation reaction. The kinetic parameters obtained from the differential reactor experiments were refined to match the fixed-bed reactor experiments. With this, the average error in predicting both ethylene conversion and selectivity to ethylene oxide was 4.3%. The apparent activation energies for the epoxidation and combustion reactions were 60.7 and 73.2 kJ/mol, respectively.