Process for manufacturing ethylene oxide using scaled selectivity values

A method of operating a process for producing ethylene oxide by reacting a feed gas comprising ethylene, oxygen, and at least one organic chloride over a high selectivity, silver-based catalyst comprising rhenium, the method comprising the steps of:

• operating the process at a first value of a reaction temperature, a first value of an overall catalyst chloriding effectiveness, and a first set of values for a set of reference operating conditions, the set of reference operating conditions comprising a plurality of reference reaction parameters, to yield a first value of a target ethylene oxide production parameter and a first actual selectivity value;
• subsequently operating the process at a second value of the reaction temperature, a second value of the overall catalyst chloriding effectiveness, and a second set of values for the set of reference operating conditions, to yield a second value of the target ethylene oxide production parameter and a second actual selectivity value;
• calculating a scaled first selectivity value from the first actual selectivity value, a value in the first set of values of a first at least one of the reference operating conditions in the set of reference operating conditions, and a reference value of the first at least one of the reference operating conditions in the set of reference operating conditions;
• calculating a scaled second selectivity value from the second actual selectivity value, a value in the second set of values of the first at least one of the reference operating conditions in the set of reference operating conditions, and the reference value of the first at least one of the reference operating conditions in the set of reference operating conditions;
• calculating a scaled first reaction temperature value from the first value of the reaction temperature, a value in the first set of values of a second at least one of the reference operating conditions in the set of reference operating conditions, and a reference value of the second at least one of the reference operating conditions in the set of reference operating conditions;
• calculating a scaled second reaction temperature value from the second value of the reaction temperature, a value in the second set of values of the second at least one of the reference operating conditions in the set of reference operating conditions, and the reference value of the second at least one of the reference operating conditions in the set of reference operating conditions;
• determining that an adjustment is required to at least one of the reaction temperature and the overall catalyst chloriding effectiveness by comparing the scaled first selectivity to the scaled second selectivity;
• and
• subsequently adjusting at least one of the reaction temperature to a third reaction temperature value and the overall catalyst chloriding effectiveness to a third overall catalyst chloriding effectiveness value, such that the scaled selectivity increases, wherein the step of subsequently adjusting is based on the first scaled selectivity value, the second scaled selectivity value, the first scaled reaction temperature, and the second scaled reaction temperature, wherein the reference operating conditions in the set of reference operating conditions are selected from the group consisting of reactor inlet pressure, reactor outlet pressure, gas hourly space velocity, composition of a reactor feed stream, concentrations of components in a reactor feed stream, composition of a reactor product stream, average compositions of components taken along a bed of the high-selectivity, silver-based catalyst, average pressure along a bed of the high-selectivity, silver-based catalyst, concentrations of components in a reactor product stream, and any ethylene oxide production parameters selected from the group consisting of ethylene oxide concentration, ethylene oxide yield, ethylene oxide production rate, ethylene oxide production rate/catalyst volume, ethylene conversion, and oxygen conversion.