Method for the decomposition of cumene hydroperoxide

Abstract

An improved method for the production of phenol, acetone and alpha-methyl styrene (AMS) from a cumene hydroperoxide and dimethylbenzyl alcohol (DMBA) mixture is described, wherein 0.5-5% additional water by weight is added prior to the final DMBA dehydration step, carried out in the presence of about 20-400 ppm mineral acid catalyst at 110-150° C. for 0.5 to 40 minutes residence time. The use of additional water allows greater flexibility in maintaining optimum temperature in the second stage over a much broader turndown range with fixed equipment, decreases the residual dicumyl peroxide (DCP) at the yield optimum for a given temperature, and increases the overall yield of AMS at optimum conditions at a given temperature.

1 . A method for the production of phenol, acetone and alpha-methyl styrene from a mixture of cumene hydroperoxide and dimethylbenzyl alcohol, which comprises:
 a first stage reaction with an acetone to phenol mole ratio of about 1.0-1.5, a water content of about 0.5 to 1.5 wt. %, a sulfuric acid concentration of about 20-400 ppm, a reactor pressure of about 450-760 mm Hg, a temperature of about 60-85° C., and a residence time of 4-45 minutes, with about 0.5 to 3 wt. % additional water then being added prior to a plug flow, and a second stage reactor maintained at about 110-150° C. with a residence time of 0.5 to 30.0 minutes.   
     
     
         2 . The method of  claim 1 , wherein the first stage reaction conditions are about 300-350 ppm sulfuric acid, about 450-500 mm Hg operating pressure, about 78-80° C. operating temperature, and a 5-6 minute residence time. 
     
     
         3 . The method of  claim 2 , wherein the acetone to phenol mole ratio is about 1.25 to 1.35, and the water content is about 1.0-1.2 wt. % in the first stage. 
     
     
         4 . The method of  claim 3 , wherein the second stage reaction conditions are a residence time of 0.7 to 1.0 minutes, about 1-2 wt. % additional added water, and a temperature of about 120-140° C. 
     
     
         5 . The method of  claim 4 , wherein exit concentrations of dicumyl peroxide are maintained at about 0.01-0.15 wt. %. 
     
     
         6 . The method of  claim 1 , wherein the first stage reaction conditions are an acetone to phenol ratio of about 1.0, a sulfuric acid concentration of about 20-50 ppm, atmospheric to slightly negative pressure, and a residence time of 15-45 minutes. 
     
     
         7 . The method of  claim 6 , wherein the second stage reaction conditions are a residence time of 5 to 20 minutes, about 1-2 wt. % additional added water, and a temperature of about 120-140° C. 
     
     
         8 . The method of  claim 4 , wherein the temperature is 134-138° C. 
     
     
         9 . The method of  claim 5 , wherein exit concentrations of dicumyl peroxide are maintained at about 0.02-0.03 wt. %. 
     
     
         10 . The method of  claim 7 , wherein the temperature is about 134-138° C. 
     
     
         11 . The method of  claim 5 , wherein exit concentrations of dicumyl peroxide are maintained at about 0.06 to 0.10 wt. %.