Conversion of an alcoholic oxygenate to propylene using moving bed technology and an etherification step

Abstract

The average propylene selectivity per on-stream cycle of an alcoholic oxygenate to propylene (OTP) process using one or more fixed beds of a dual-function oxygenate conversion catalyst is substantially enhanced by the use of a feed pretreatment step involving a catalytic etherification reaction, by switching to moving bed reactor technology in the olefin synthesis portion of the OTP flow scheme in lieu of fixed bed technology and by the selection of a catalyst on-stream cycle time of 300 hours or less. These provisions hold the build-up of coke deposits to a level which does not substantially degrade catalyst activity, oxygenate conversion and propylene selectivity, thereby enabling maintenance of propylene average cycle yield at essentially start-of-cycle levels. The propylene average cycle yield improvement of the present invention over that achieved by the fixed bed system of the prior art is of the order of about 1.5 to 5.5 wt % or more.

Description

Background of the invention [0001] In general, the present invention relates to the use of etherification reactions in the pretreatment steps of alcohol oxygenate feedstocks and the use of moving bed technology in the hydrocarbon synthesis reaction zone of oxygenate to propylene (OTP) processes. These features, combined with the relatively short OTP catalyst on-line cycle time, allow the level of OTP catalyst coking not to significantly reduce the activity and propylene selectivity of the bifunctional catalyst used in this OTP process. These three measures significantly increase the average propylene yield achievable by this process over its catalyst on-line cycle time relative to the average cycle propylene yield achievable by the existing process for oxygenate conversion to The reaction of hydrocarbons uses fixed bed technology and operates at much longer catalyst cycle times. [0002] A large part of the global petrochemical industry is concerned with the production of lig...

AI Technical Summary

Problems solved by technology

This MTP process is further described in Rothaemel et al. "Demonstrating the New Methanol to Propylene (MTP) Process" (presented at the ERTC Petrochemical Conference, Paris, France, March 2003): On-Line Process Cycles Before In-Situ Regeneration Becomes Necessary The phase is expected to be 500-700 hours, and in the first 5 cycles, the transformation activity is significantly reduced

Images