Ethylene Oxide Formation in a Microreactor: From Qualitative Kinetics to Detailed Modeling

Abstract

Silver/α-alumina catalysts were wash-coated in stainless steel microchannels. The microchannels were used for the epoxidation of ethylene. Pure silver microplates were also investigated giving the highest activities and selectivities toward the ethylene oxide formation. Pretreatment conditions with oxygen and ethylene for the pure silver catalyst were studied and optimized. The experiments were carried out under atmospheric pressure, varying the temperature from 220 to 300 °C and the total gas flow from 5.4 to 10.5 cm3/min. A precise kinetic model for the ethylene oxide formation in pure silver microchannels was developed at 260 °C. The model was based on the competitive adsorption of ethylene and molecular oxygen over the silver surface. The concentrations of the reactants (oxygen and ethylene) in the gas flow were systematically varied from 5 to 25 vol % using helium gas as balance. The model was confronted with experimental data obtained in the microchannels, resulting in a very high degree of explanation (97%).