INHERENTLY SAFE ODH OPERATION

摘要

In the operation of an oxidative dehydrogenation (ODH) process, it is desirable to remove oxygen in the product stream for a number of reasons, including to reduce oxidation of the product. This may be achieved by having several pre-reactors upstream of the main reactor having a catalyst system containing labile oxygen. The feed passes through one or more reactors saturated with labile oxygen. When the labile oxygen is consumed through a valve system, the pre-reactor accepts product from the main reactor and complexes reactive oxygen in the product stream until the catalyst system is saturated with labile oxygen. Then the reactor becomes a pre-reactor and another pre-reactor becomes a scavenger.

主权项

1. A process for the catalytic oxidative dehydrogenation of one or more C2-4 alkanes comprising n pre-reactors for the oxidative dehydrogenation of said alkanes in the presence of a mixed metal oxide oxidative dehydrogenation catalyst system which complexes reactive oxygen in the catalyst system, where n is an integer of 2 or more, and one or more downstream main oxidative reactors comprising:
i) passing a feed stream comprising said one or more C2-4 alkanes through one or more of n−1 pre-reactors at a temperature from about 300° C. to about 500° C. and a pressure from about 3.447 kPag to about 689.47 kPag (about 0.5 to about 100 psig) to oxidatively dehydrogenate at least a portion of the feedstream until the oxidative dehydrogenation catalyst is depleted of reactive oxygen; ii) diverting the feed stream from the pre-reactor in which the oxidative dehydrogenation catalyst is depleted of reactive oxygen to a pre-reactor in which the oxidative dehydrogenation catalyst is substantially saturated with reactive oxygen; iii) passing the product stream from said n−1 pre-reactor together with additional oxygen feed to one or more downstream main reactors at a temperature from about 300° C. to about 500° C. and a pressure from about 3.447 kPag to about 689.47 kPag (about 0.5 to about 100 psig) for the oxidative dehydrogenation of said one or more C2-4 alkanes; iv) removing a product stream from said one or more downstream main reactors comprising corresponding C2-4 alkenes, unreacted C2-4 alkanes, unreacted oxygen and water vapor and passing it through one or more pre-reactors depleted of reactive oxygen at a temperature from about 50° C. to about 270° C. and a pressure from about 3.447 kPag to about 689.47 kPag to complex the oxygen in the product stream and increase the reactive oxygen saturation of the oxidative dehydrogenation catalyst with reactive oxygen and recovering a product stream substantially free of oxygen; v) continuing step iv) until either:
a) there is another pre-reactor more depleted of reactive oxygen than that through which the product stream is being passed; orb) the oxidative dehydrogenation catalyst in the pre-reactor is substantially saturated with reactive oxygen; vi) switching the flow of product stream from the formerly reactive oxygen depleted pre-reactor to a more reactive oxygen depleted pre-reactor; and vii) optionally completely saturating the oxidative dehydrogenation catalyst with reactive oxygen in said formerly reactive oxygen depleted pre-reactor; and viii) bringing on line the formerly reactive oxygen depleted pre-reactor.