System and method for selective trimerization

A method for separating catalyst, unreacted ethylene, and polymeric by-products from 1-hexene in a reactor effluent from a continuous process for selectively trimerizing ethylene to 1-hexene, which method comprises:

• A) in a reactor, selectively trimerizing ethylene in a reaction diluent using a homogeneous organometallic catalyst system to produce a pressurized, liquid reactor effluent comprising 1-hexene reaction product, unreacted ethylene, polymeric by-product, catalyst material, reaction diluent and optionally C8+ olefin;
• B) reducing the pressure of said liquid reactor effluent to provide reduced pressure liquid reactor effluent;
• C) contacting said reduced pressure effluent with a heated heat transfer solvent under conditions of temperature, pressure, and flow rate which are effective to subsequently flash vaporize substantially all of said 1-hexene reaction product and said unreacted ethylene, but which conditions are not effective to subsequently vaporize any major portion of said polymeric by-product and said catalyst material;
• D) separating said reduced pressure effluent in a flash separator into a vapor phase comprising substantially all of said 1-hexene reaction product and said unreacted ethylene, along with some reaction diluent and a minor portion of said heat transfer solvent;
• and a liquid phase comprising substantially all of said polymeric by-products and said catalyst material, along with some reaction diluent and a major portion of said heat transfer solvent;
• E) subjecting said vapor phase from said flash separator to one or more distillation steps sufficient to recover 1-hexene, unreacted ethylene, reaction diluent, heat transfer solvent, and optionally C8+ olefin;
• F) recirculating a first portion of said heat transfer solvent-containing liquid phase from said separator through a heater and then into contact with said reduced pressure liquid reactor effluent as set forth in Step C;
• and
• G) continuously or intermittently forming as a purge stream a second portion of said liquid phase from said separator in order to remove polymeric by-products and catalyst material from the flash separator and the recirculating first portion of said liquid phase and to prevent buildup therein of said polymeric by-products and catalyst material.

A method for passivating catalyst metals in, and recovering passivated catalyst metals, polymeric by-products, reaction diluent and heat transfer solvent from, a portion of a treated effluent stream from a reactor for the catalytic trimerization of ethylene to 1-hexene, which method comprises:

• A) providing a liquid portion of a treated reactor effluent stream, which liquid portion comprises organometallic catalyst material, polymeric reaction by-products, reaction diluent, and heat transfer solvent;
• B) feeding a fraction of said liquid portion as a purge stream to a steam-stripping vessel containing liquid water;
• C) introducing steam, and optionally also additional liquid water, into said stripping vessel, along with said purge stream, under conditions of temperature and pressure which are effective to deactivate/passivate said purge stream catalyst material, to solidify said purge stream polymeric reaction by-product material into removable particles, and to at least partially volatilize said purge stream reaction diluent and/or heat transfer solvent;
• D) removing said deactivated catalyst material and said polymeric by-product particles from said steam stripping vessel via one or more liquid streams, while also removing volatilized diluent and heat transfer solvent from said steam stripping vessel via an overhead vapor stream formed by venting of steam from said stripping vessel;
• E) recovering said deactivated catalyst material and said polymeric by-product particles by separating said material and particles from said one or more liquid streams from the stripping vessel;
• and
• F) recovering said volatilized reaction diluent and heat transfer solvent from said overhead vapor stream from the stripping vessel.