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 at least three pre-reactors and one or more downstream main oxidative dehydrogenation reactors comprising:
i) passing a feed stream comprising said one or more C2-4 alkanes through a first pre-reactor containing a dehydration catalyst that is saturated with reactive oxygen; ii) reacting the feed stream with the dehydration catalyst that is saturated with reactive oxygen at a temperature from about 300° C. to about 500° C. and a pressure from about about 0.5 to about 100 psig to produce a partially dehydrogenated stream comprising unreacted C2-4 alkanes; iii) passing the partially dehydrogenated stream together with additional oxygen feed to one or more downstream main oxidative dehydrogenation reactors; iv) oxidatively dehydrogenating the partially dehydrogenated stream at a temperature from about 300° C. to about 500° C. and a pressure from about 0.5 to about 100 psig to produce a product stream; v) removing the product stream from said one or more downstream main oxidative dehydrogenation reactors comprising corresponding C2-4 alkenes, unreacted C2-4 alkanes, unreacted oxygen and water vapor; vi) passing the product stream through a series of two or more pre-reactor comprising a lead and a guard dehydrogenation reactor having secondary dehydrogenation catalyst that are depleted of reactive oxygen the lead dehydrogenation reactor having a secondary dehydrogenation catalyst that is less depleted of reactive oxygen than the dehydrogenation catalyst in the guard dehydrogenation reactor; vii) ′reacting the product stream with the dehydrogenation catalyst of the lead dehydrogenation reactor depleted of reactive oxygen at a temperature from about 50° C. to about 270° C. and a pressure from about 0.5 to about 100 psig to complex the oxygen depleting oxygen from the product stream and regenerating oxidative dehydrogenation catalyst by increasing the saturation with reactive oxygen; and viii) reacting the product stream from the lead dehydrogenation reactor with the reactive oxygen depleted catalyst of the guard oxygen dehydrogenation reactor at a temperature from about 50° C. to about 270° C. and a pressure from about 0.5 to about 100 psig to complex the oxygen depleting oxygen from the product stream and partially regenerating oxidative dehydrogenation catalyst by increasing the saturation with reactive oxygen; and ix) recovering a product stream depleted of oxygen; recovering a product stream depleted of oxygen; x) continuing step (i) to (ix) until either:
a) the pre-reactor comprising the first dehydrogenation catalyst and through which the feed stream is being passed is depleted of reactive oxygen or is more depleted or reactive oxygen than another pre-reactor; orb) the pre-reactor comprising the second oxidative dehydrogenation catalyst through which the product stream is being passed is substantially saturated with reactive oxygen; xi) when condition (a) is achieved the feed stream is diverted from the first pre-reactor to lead dehydrogenation reactor that is more saturated with reactive oxygen the product stream from the main dehydrogenation reactors is diverted to the guard dehydrogenation reactor and the product stream from the guard dehydrogenation reactor is diverted to the primary dehydrogenation reactor in which the dehydrogenation catalyst is depleted of reactive oxygen and the process continues from step (i) on.