Kinetic study of ethylene oxidation in a Berty reactor

Abstract

Ethylene oxidation reactions were studied in a Berty reactor (an example of a continuously stirred tank reactor (CSTR)) using a commercial silver catalyst supported on α-alumina. Reaction rates were measured using a gas feed containing ethylene (3% - 6.5%) and oxygen (18% - 19.5%), the balance being nitrogen. The reactions were carried out at a pressure of 2170 kN m-2 and at a temperature varying from 513 to 593 K. The Berty reactor used in this investigation was found to behave as a CSTR with perfect mixing. The kinetic data obtained for the ethylene oxidation were free from external and internal mass- and heat-transfer limitations. Rate expressions for ethylene conversion to ethylene oxide and to carbon dioxide were obtained as follows. (1) Rate of ethylene oxide production (mol (g cat.)-1 h-1) rC2H4O = (2.259 × 107) exp(-9010 T)(PO2)0.5(PC2H4)0.61 + (1.985 × 102) exp(2400T)(PCO2). (2) Rate of carbon dioxide production (mol (g cat.)-1 h-1) rCO2 = (4.34 × 107) exp(-10800 T)(PO2)0.5(PC2H4)0.51 + (1.08 × 102) exp(1530T)(PCO2). It was observed that the catalyst selectivity towards ethylene oxide decreased with an increase in the total ethylene conversion, and the temperature was found to have a negligible effect on selectivity. Carbon dioxide was found to have an inhibiting effect on both ethylene oxide and carbon dioxide reaction rates. © 1988.