Catalysts Useful for the Alkylation of Aromatic Hydrocarbons

Abstract

A catalyst useful for the alkylation or transalkylation of aromatic compounds is disclosed. The catalyst is an acid-treated zeolitic catalyst produced by a process including contacting an acidic zeolitic catalyst comprising surface non-framework aluminum and framework aluminum with an organic dibasic acid at a catalyst to acid weight ratio in the range from about 2:1 to about 20:1 and at a temperature in the range from about 50° C. to about 100° C. to selectively remove at least a portion of the surface non-framework aluminum. The resulting catalyst may have a measured first-order rate constant, k cum , for the alkylation of benzene with propylene to form cumene, of at least 2.0 cm 3 /s g.

What is claimed: 
     
         1 . A method for improving the activity of acidic zeolitic catalysts, the method comprising:
 contacting an acidic zeolitic catalyst comprising surface non-framework aluminum and framework aluminum with an organic dibasic acid at a catalyst to acid weight ratio in the range from about 2:1 to about 20:1 and at a temperature in the range from about 50° C. to about 100° C. for a duration of up to about 2 hours to selectively remove at least a portion of the surface non-framework aluminum, thereby forming a selectively dealuminated zeolitic catalyst;   wherein the selectively dealuminated zeolitic catalyst has a measured first-order rate constant, k cum , for the alkylation of benzene with propylene to form cumene, of at least 2.0 cm 3 /s g.   
     
     
         2 . The method of  claim 1 , further comprising:
 forming an aqueous solution of the organic dibasic acid;   admixing the acidic zeolitic catalyst with the aqueous solution for the contacting;   separating the acid-contacted zeolitic catalyst from the aqueous solution;   washing the acid-contacted catalyst to remove any excess organic dibasic acid; and   drying the washed catalyst at a temperature in the range from about 80° C. to about 150° C.   
     
     
         3 . The method of  claim 1 , wherein the contacting a zeolitic catalyst with an organic dibasic acid removes essentially no surface framework aluminum. 
     
     
         4 . The method of  claim 1 , wherein the catalyst to acid weight ratio is in the range from about 6:1 to about 8:1. 
     
     
         5 . The method of  claim 4 , wherein the selectively dealuminated zeolitic catalyst has a measured first-order constant, k cum , for the alkylation of benzene with propylene to form cumene, of at least 3 cm 3 /s g. 
     
     
         6 . The method of  claim 1 , wherein the organic dibasic acid comprises at least one of oxalic acid, malonic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, tartaric acid, ethylene diamine tetra-acetic acid, and mixtures thereof. 
     
     
         7 . The method of  claim 1 , wherein the zeolitic catalyst comprises at least one of a silica-alumina and an alunimosilicate. 
     
     
         8 . The method of  claim 1 , wherein the contacting is at a temperature in the range from about 65° C. to about 90° C. and is performed for a duration of between 0.5 and 1.5 hours. 
     
     
         9 . The method of  claim 1 , wherein the zeolitic catalyst comprises at least one of zeolite Beta, ZSM-5, ZSM-22, ZSM-23, MCM-22, and MCM-49. 
     
     
         10 . The method of  claim 1 , wherein the acidic zeolitic catalyst comprises high performance beta zeolite and wherein the selectively dealuminated zeolitic catalyst has a measured first-order rate constant, k cum , for the alkylation of benzene with propylene to form cumene, of at least 4 cm 3 /s g.