Process for the production of ethylene oxide

A process for the epoxidation of ethylene comprising:

• contacting an inlet feed gas comprising ethylene, oxygen and one or more reaction modifiers consisting of organic chlorides with an epoxidation catalyst comprising a carrier, and having silver, a rhenium promoter, and one or more alkali metal promoters deposited thereon;
• wherein the inlet feed gas has an overall catalyst chloriding effectiveness value (Cleff) represented by the formula:—
• Cl
• eff
• =
• (
• 0.1
• *
• [
• MC
• ]
• +
• [
• EC
• ]
• +
• 2
• *
• [
• EDC
• ]
• +
• [
• VC
• ]
• )
• (
• 0.002
• *
• [
• CH
• 4
• ]
• +
• [
• C
• 2
• ⁢
• H
• 6
• ]
• +
• 0.01
• *
• [
• C
• 2
• ⁢
• H
• 4
• ]
• )
• (
• I
• )
• wherein [MC], [EC], [EDC], and [VC] are the concentrations in ppmv of methyl chloride (MC), ethyl chloride (EC), ethylene dichloride (EDC), and vinyl chloride (VC), respectively, and [CH4], [C2H6] and [C2H4] are the concentrations in mole percent of methane, ethane, and ethylene, respectively, in the inlet feed gas;
• wherein at an initial cumulative ethylene oxide production cumEO1 of at least 0.2 kton ethylene oxide/m3 catalyst, said process is operating at a reaction temperature having a value T1 and with the inlet feed gas having an optimum overall catalyst chloriding effectiveness value of Cleff1 to produce ethylene oxide with an ethylene oxide production parameter at a target value EO1;
• and characterised in that the carrier is a fluoride-mineralized alpha-alumina carrier and said process is subsequently operated such that at a cumulative ethylene oxide production cumEOx, wherein cumEOx is at least 0.6 kton ethylene oxide/m3 catalyst greater than cumEO1, the reaction temperature has an increased value Tx to maintain said ethylene oxide production parameter at the target value EO1 whilst the optimum overall catalyst chloriding effectiveness value of the inlet feed gas Cleffx is controlled such that the ratio of Cleffx/Cleff1 is in the range of from 0.8 to 1.2, wherein the value T1 is the reaction temperature when the ethylene oxide production is at cumEO1, and wherein the value Tx is greater than the value T1 by at least 3° C.