CONTINUOUS ETHYLENE TETRAMERIZATION PROCESS

摘要

A continuous flow process for the oligomerization of ethylene using a chromium catalyst having a phosphorus-nitrogen-phosphorus (“P—N—P”) ligand provides high selectivity to the desired tetramer (1-octene) with reduced production of coproduct C10+ oligomers. Prior art processes that maximize catalyst activity have provided comparatively poor product selectivity. In particular, the production of larger amounts of C10+ oligomers have been observed under conditions that maximize activity. The present process resolves this problem through the use of a combination of low catalyst concentration and by limiting the octene concentration in the reactor.

主权项

1. A continuous flow process for the oligomerization of ethylene, said process comprising
I) adding ethylene and solvent to a mixed reactor and contacting said ethylene under oligomerization conditions with
1) a diphosphine catalyst defined by the formula (R1)(R2)-P1-bridge-P2(R3)(R4) wherein R1, R2, R3 and R4 are independently selected from the group consisting of hydrocarbyl and heterohydrocarbyl and the bridge is a moiety that is bonded to both phosphorus atoms;2) a source of Cr; and3) an activator II) removing a product discharge stream comprising hexene, octene, C10+ oligomers and solvent from said reactor; and III) controlling the flow of said solvent to said reactor such that the product discharge stream contains from 2 to 25 weight % octene, based on the weight of hexene, octene, C10+ oligomers and solvent; andwherein said process is further characterized by being conducted at a catalyst concentration of from 0.3 to 5 micromolar Cr.