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.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an improved method for the production of phenol, acetone and alpha-methyl styrene (AMS) from a cumene hydroperoxide and dimethylbenzyl alcohol (DMBA) mixture.BACKGROUND OF THE INVENTION[0002]The dominant method for producing phenol and acetone is via air oxidation of cumene to cumene hydroperoxide (CHP), followed by acid catalyzed decomposition of the CHP selectively to phenol and acetone. Dimethylbenzyl alcohol (DMBA) is formed as the principal side product in the oxidation step, and is subsequently dehydrated to alpha-methyl styrene (AMS) in the same acid catalyzed decomposition step.[0003]The acid catalyzed decomposition of CHP is well known, most modern processes utilizing a two step, continuous flow approach to optimize overall yield in this step, especially of DMBA to AMS. Examples of such prior art are U.S. Pat. Nos. 7,482,493, 7,109,385, 6,307,112, 6,225,513, 6,201,157, 6,057,483, 5,998,677, 5,463,136, 5,430,200, 5...

AI Technical Summary

Benefits of technology

[0008]The present invention relates to a method for the production of phenol, acetone, and alpha-methyl styrene from a mixture of cumene hydroperoxide and dimethylbenzyl alcohol wherein the first stage is carried out with an acetone to phenol mole ratio of 1.0-1.5, water content of 0.5 to 1.5 wt. %, sulfuric acid concentration of 20-400 ppm, a reactor pressure of 500-760 mmHg, and a temperature of 60-85° C., being optimized to maximize the yield of dicumyl peroxide from cumene hydroperoxide and dimethylbenzyl alcohol under any specific set of feed and operational conditions. Additional water, 0.5 to 5 wt. %, is then added prior to the second stage which is maintained preferably at 130-140° C., regardless of residence time by controlling the rate of water addition. Water addition at a fixed temperature is then further refined to minimize residual dicumyl peroxide and maximize overall dimethylbenzyl alcohol to alpha-methyl styrene yield.

Problems solved by technology

All of these approaches have plusses and minuses, typically requiring recycling of significant amounts of product material back to this part of the process, higher levels of acid catalyst (thus requiring more base to neutralize the reaction product prior to distillation) and / or additional complexity in both equipment count and control, for what in most cases is a marginal gain in selectivity over commonly practiced optimized approaches.

Many approaches do not consider potential detrimental downstream impacts in terms of yield, energy, product quality and equipment count / complexity.

However, since DMBA, water and AMS are in equilibrium in the second stage, it was expected that the DMBA concentrations would be significantly higher at the same optimum DCP range, resulting in a slight yield penalty.

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