PROCESS FOR REDUCING THE OVERCHLORIDING OF HIGH SELECTIVITY ETHYLENE OXIDE CATALYSTS DURING RESTARTS

Abstract

Disclosed herein are methods of improving the restart performance of a high-selectivity ethylene oxide catalyst that has been shut down due to a planned or unplanned outage. It is believed that the proper selection of process variables on restart avoids exacerbating catalyst surface overchloriding that may occur when subsurface chlorides are diffused to the catalyst surface. In accordance with the method, the initial restart reaction temperature is no more than five (5) degrees Celsius above an initial start-up steady-state reaction temperature on fresh catalyst and is no more than five (5) degrees Celsius below the initial start-up steady-state reaction temperature. The addition of a make-up organic chloride to the reactor feed gas is deferred until the reactor outlet oxygen concentration equals or exceeds 0.5 mole percent and until a relative scaled reactor vinyl chloride feed gas concentration is no greater than 110 percent.

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