In the presence ofethylene oxide silver catalyst, the direct oxidation of ethyleneand oxygen to produce ethylene oxide (EO) is an important catalytic reaction inthe petrochemical industry. Silver catalyst is the only effective industrialcatalyst for the direct oxidation of ethylene to produce ethylene oxide. It isa kind of supported catalyst. Its carrier is α-Al2O3 with low specific surfacearea, and additives and auxiliaries are commonly used to improve the performanceof the catalyst.

Ethyleneand oxygen are directly epoxidized under the action of a silver catalyst toproduce EO, and also produce by-products of CO2 and water. Silvercatalyst has three main performance index: activity, selectivity and stability.Activity refers to the temperature of a given load (space-time yield) in acertain reaction condition ( reaction gas composition, space velocity, etc.). Selectivityrefers to the mole percent of ethylene converted to EO vs. the total conversionof ethylene. Stability refers to the declining rate of catalyst activity in thereaction process. In the era of high oil prices, the selectivity of catalyticreactions plays a decisive role in the economic benefits of the EO / EGproduction process.

Atpresent, the domestic ethylene oxide / ethylene glycol (EO / EG) productionequipment has 43 sets, and a charge of silver catalyst is more than 5200m3.The use of silver catalyst has three types:

First,high activity silver catalyst, the initial selectivity of 80 ~ 82%, the servicelife of 2-4 years, for the 20th century construction, unmodified EO / EG devices;

Second,high selectivity of silver catalyst, the highest selectivity of up to 88-90%,for CO2 concentration in inlet gas of less than 1.0%, space-timeyield ≤200kgEO/h/m3 of the new EO/EG devices;

Third,medium selectivity silver catalyst, the maximum selectivity of about 85-87%,for CO2 concentration in inlet gas of less than 3.0%, space-timeyield ≤260kgEO/h/m3 of EO/EG devices.

Inthe world, there are mainly Shell, SD, DOW Chemical and Sinopec and a few othercompanies who could provide ethylene oxide silver catalyst. Yanshan Branch ofBRICI is the only research institution of ethylene oxide silver catalyst in China,which has 43 years of research history and can provide series of silvercatalyst products with selectivity from 82 to 90%. These catalysts can meet therequirements of different processes of EO/EG devices at home and abroad, which havebeen put into industrial application in 15 EO/EG production enterprises for 55times, and won the users' high praise. At present, medium selectivity and highselectivity silver catalysts developed by Yanshan branch have become mainstreamproducts of silver catalyst market.