Stripping hydrocarbon in an oxygenate conversion process

Abstract

A process for method for the production of olefin product from an oxygenate-containing feedstock includes exposing a silicoaluminophosphate catalyst to an oxygenate-containing feedstock in a reaction zone under conditions effective to convert the oxygenate-containing feedstock to an olefin product, by stripping at least a portion of the exposed catalyst with a stripping gas; and returning at least a portion of the stripped catalyst directly to the reaction zone.

What is claimed is:  
     
         1 . A method for the production of olefin product from an oxygenate-containing feedstock, comprising: 
 exposing a molecular sieve catalyst to an oxygenate-containing feedstock in a reaction zone under conditions effective to convert the oxygenate-containing feedstock to an olefin product;    stripping at least a portion of the exposed catalyst with a stripping gas; and    returning at least a portion of the stripped catalyst to the reaction zone without regenerating.    
     
     
         2 . The method of  claim 1 , further comprising regenerating at least a portion of the stripped catalyst and returning at least a portion of the regenerated catalyst to the reaction zone.  
     
     
         3 . The method of  claim 1 , wherein a ratio defined by time of exposing the catalyst to the oxygenate containing feedstock to time of stripping the exposed catalyst with the stripping gas is from 1:1 to 20:1.  
     
     
         4 . The method of  claim 1 , wherein a ratio defined by time of exposing the catalyst to the oxygenate containing feedstock to time of stripping the exposed catalyst with the stripping gas is greater than 20:1.  
     
     
         5 . The method of  claim 1 , wherein the stripping gas is selected from the group consisting of steam, nitrogen, air, helium, argon, methane, carbon dioxide, carbon monoxide, flue gas, hydrogen, and combinations thereof.  
     
     
         6 . The method of  claim 1  wherein the stripping gas comprises steam.  
     
     
         7 . The method of  claim 6  wherein the stripping gas flows at a rate of 1 to 10 lbs per hour per 1000 lbs of catalyst per hour.  
     
     
         8 . The method of  claim 7  wherein the stripping gas flows at a rate of 1 to 4 lbs per hour per 1000 lbs of catalyst per hour.  
     
     
         9 . The method of  claim 1 , wherein the stripped catalyst is stripped in a separate unit apart from the regenerator.  
     
     
         10 . The method of  claim 1 , wherein the stripping of the exposed catalyst removes at least 25% of the hydrocarbons adhered thereto.  
     
     
         11 . The method of  claim 1 , wherein the stripping of the exposed catalyst removes at least 50% of the hydrocarbons adhered thereto.  
     
     
         12 . The method of  claim 1  wherein the stripped catalyst contains less than 10% by weight of hydrocarbons selected from the group consisting of olefins, aromatics, parafins, oxygenates, and mixtures thereof.  
     
     
         13 . The method of  claim 1 , wherein the oxygenate-containing feedstock comprises at least one compound selected from the group consisting of methanol; ethanol; n-propanol; isopropanol; C 4 -C 20  alcohols; methyl ethyl ether; dimethyl ether; diethyl ether; di-isopropyl ether; formaldehyde; dimethyl carbonate; dimethyl ketone; acetic acid; and mixtures thereof.  
     
     
         14 . The method of  claim 1 , wherein the molecular sieve catalyst comprises a silicoaluminophosphate molecular sieve and a binder.  
     
     
         15 . The method of  claim 14 , wherein the silicoaluminophosphate molecular sieve is selected from the group consisting of SAPO-5, SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, SAPO-56, metal containing forms thereof, and mixtures thereof.  
     
     
         16 . The method of  claim 14 , wherein the silicoaluminophosphate molecular sieve has a Si:Al atomic ratio of at least 0.30.  
     
     
         17 . The method of  claim 1 , wherein the reaction zone comprises temperatures of about 350 to 550° C. while exposing the molecular sieve catalyst to the oxygenate-containing feedstock.  
     
     
         18 . The method of  claim 1 , wherein the oxygenate-containing feedstock contacts the molecular sieve catalyst in the reaction zone at an average gas superficial velocity of greater than 1 meter per second.  
     
     
         19 . An olefin product made according to the method of  claim 1 .  
     
     
         20 . The method of  claim 1 , further comprising contacting the olefin product with a polyolefin-forming catalyst under conditions effective to form a polyolefin.  
     
     
         21 . A polyolefin made by the process of  claim 20.