Cyclohexane oxidation process

B. T. Matusz and D. L. Sadler, A Comprehensive Program for Preventing Cyclohexane Oxidation Process Piping Failures, Paper presented at AIChE Loss Prevention Symposium, Houston, Texas, Mar./Apr. 1993. 

The selectivity of the oxidation of cyclohexane toward the desired products cyclohexanone and cyclohexanol very much depends on the degree of conversion of cyclohexane per pass. Both cyclohexanone and cyclohexanol are much more reactive than the starting material cyclohexane. And as a result, at a high degree of conversion of cyclohexane per pass, a significant fraction of the valuable products cyclohexanone and cyclohexanol are overoxidized to by-products. This overoxidation is limited at a low degree of conversion per pass. Selectivity drops up to 5% per percent conversion of cyclohexane are reported. As a consequence, for economic reasons, cyclohexane oxidation processes have to be operated at... 

A traditional catalyzed cyclohexane oxidation process consists of an oxidation and heat recovery section, a neutralization and decomposition section, a cyclohexane recovery section, a cyclohexanone separation and purification section, and finally a cyclohexanol dehydrogenation section. A simplified diagram of such a catalyzed cyclohexane oxidation process that is operated in a continuous mode is shown in the following ... 

DSM developed the noncatalyzed DSM Oxanone cyclohexane oxidation process in order to overcome the disadvantages of the traditional catalyzed cyclohexane oxidation process, namely, high cyclohexane and NaOH consumption figures and a large number of downtime hours. In addition, the DSM Oxanone process produces, after decomposition of CHHP, a KA oil with a KA ratio of more than 1.5 that requires a cyclohexanol dehydrogenation section with just a limited capacity. 

Although the cyclohexane oxidation process has already a long commercial history, still a lot of (patent) publications are issued each year. The main topic of these (patent) publications is related to the selectivity or carbon efficiency of the oxidation and decomposition step. Other topics of these (patent) pubhcations are related to, for example, improving the energy efficiency of the process, treating/upgrading the by-product containing streams, and the application of dedicated apparatus in the process. 

It is expected that process improvements of the cyclohexane oxidation process aiming at improved variable costs such as reduced consumption of the raw materials cyclohexane and sodium hydroxide, reduced energy consumption, and upgrading the value of the various by-product streams will continue. On the other hand, it is observed that small-scale units (e.g., 45 kt/annum) are phased out and replaced by larger-scale units in order to reduce the fixed costs. 

During the last five years we have investigated the possibility of using the Gif system for industrial cyclohexane oxidation. We first studied the Gif system, later the GoAgg GoAgg and the GoChAgg systems. We wish to report here our results and evaluate the possibility of substituting the classical cyclohexane oxidation process by a process based on the Gif system. 

The GoAgg system shows a good potential for substituting for the classical cyclohexane oxidation process. In the presence of hydrochloric acid it produces a 0.267 M solution of one + ol with 100% selectivity in 60 min of reaction time. In comparison with the classical process (0.3 M solution of one + ol with only 80% selectivity in 40 min) these results are totally compatible but have the advantage of being obtained at room temperature without applying pressure. On the other hand, the turnover numbers are low... 

Computer-Aided Development of the Cyclohexane Oxidation Process... 

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