Alkylene oxide catalyst and use thereof

Abstract

A supported silver catalyst and use thereof in a process for producing an alkylene oxide, such as ethylene oxide, by the direct oxidation of an alkylene with oxygen or an oxygen-containing gas, wherein the catalyst provides improved stability and improved resilience to reactor upsets and timely recovery to substantially pre-upset levels of catalyst activity and / or efficiency. In some embodiments, the catalyst also exhibits improved activity. A catalyst capable of producing ethylene oxide at a selectivity of at least 87 percent while achieving a work rate of at least 184 kg / h / m3 at a temperature of no greater than 235° C. when operated in a process where the inlet feed to a reactor containing the catalyst comprises ethylene, oxygen, and carbon dioxide, wherein the concentration of carbon dioxide in the inlet feed is greater than or equal to 2 mole percent.

Description

CROSS-REFERENCE TO PRIOR APPLICATION[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 792,712 filed Apr. 18, 2006.BACKGROUND OF THE INVENTION[0002]This invention pertains to a supported silver catalyst, its manufacture, and its use in the production of an alkylene oxide, particularly, ethylene oxide, directly from oxygen and an olefin, such as ethylene.[0003]Alkylene oxides are known for a multiplicity of utilities. Ethylene oxide, for example, is used to produce ethylene glycol, which is used in preparing polyester fibers and resins, nonionic surfactants, glycol ethers, ethanolamines, and polyethylene polyether polyols. Propylene oxide is used to produce propylene glycol and polypropylene polyether polyols, which are used in polyurethane polymer applications.[0004]The manufacture of ethylene oxide by the direct reaction of ethylene with oxygen or an oxygen-containing gas in the presence of a silver catalyst is an old and well developed art. An outline...

AI Technical Summary

Benefits of technology

[0022]In one embodiment, the supported silver catalyst exhibits improved activity of at least about 3° C. under STANDARD ETHYLENE EPDXIDATION PROCESS CONDITIONS as compared with a second supported silver catalyst comprised of the same materials except that the second catalyst does not contain manganese. In another embodiment, the supported catalyst, when used in a process for the oxidation of alkylene with oxygen to form an alkylene oxide, is capable of achieving an efficiency of greater than about 75 percent alkylene oxide at a workrate of greater than about 4 kg-mol alkylene oxide / h / m3 of catalyst. In still another embodiment, the supported catalyst, when used in a process for the oxidation of alkylene in the presence of oxygen to form an alkylene oxide, and when subjected to a reactor upset, is capable of recovering to greater than about 80 percent of the pre-upset activity and / or efficiency in about 3 days or less. In one embodiment, the supported catalyst has increased catalyst stability as compared to a second supported silver catalyst comprised of the same materials except that the second catalyst does not contain at least one second promoter selected from the group consisting of sodium, lithium, and mixtures thereof.

[0034]The present invention further includes a process for producing ethylene oxide comprising contacting a reactor feed comprising ethylene, oxygen, and carbon dioxide with a catalyst bed comprising any one or more of the foregoing catalysts. In one embodiment of the process, the concentration of carbon dioxide in the reactor feed is greater than or equal to 2 mole percent. In one embodiment of the process, the reactor feed further comprises one or more chlorine-containing reaction modifier species, and the concentration of the chlorine-containing reaction modifier species in the reactor feed is such that the selectivity towards ethylene oxide formation is optimal.

Problems solved by technology

Reactor upsets frequently present recovery problems with the catalyst.

Catalyst activity and / or efficiency may not recover to pre-upset levels as quickly as desired.

Worse still, the catalyst may never recover to pre-upset levels of activity and / or efficiency, but rather may settle into lower activity and / or efficiency levels.

Each reactor upset results in lost productivity; but often the effect is permanent, rather than temporary, because the catalyst fails to recover its former activity and / or efficiency.

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