Study Produce Ka Oil Through Oxidizing Cyclohexane Without Catalyst

Adipic acid is an important organic and chemical material and widelyused in industries of nylon66, polyamide and polyurethane, etc. Currently,it is mainly produced through two-step oxidation method. In thisproduction process, cyclohexane is firstly converted into cyclohexylhydrogen peroxide (CHHP) with normal air or lean-oxygen air withoutcatalyst. The mixture of cyclohexanone and cyclohexanol (traditionalnamed KA oil) is obtained through catalytic decomposition of CHHPfollowed by removing unreacted cyclohexane and other by-products. Theadipic acid is synthesized with refined KA oil through nitric acid oxidationmethod. There are mainly two industrial production processes when usingcyclohexane as raw material through noncatalytic oxidation method toproduce cyclohexanone and cyclohexanol. One is French Grand PollyCompany’s lean-oxygen oxidation and acid decomposition process, and theother is Holland DSM Company’s air oxidation and alkaline decompositionprocess. In lean-oxygen oxidation and acid decomposition process(homogeneous reaction), technological problems such as chromate scalingon pipeline and short device operation cycle will exist in this methodduring synthesizing KA oil with cyclohexane. Furthermore, the unitconsumption of producing KA oil is higher than that the process of airoxidation and alkaline decomposition method (heterogeneous reaction). However, the method of air oxidation and alkaline decomposition needs toconsume much caustic alkali and also produce much waste alkali liquid tobe treated.The purpose of this investigation is to study and compare cyclohexanedifferent oxidation methods (air and lean-oxygen air), CHHP differentdecomposition processes and the comparison of unit consumption betweenFrench Grand Polly Company and Holland DSM Company. The seriousscaling problem on pipeline in French Grand Polly Company’s productionprocess will also be investigated. A better solution will be addressed basedon those studies. This can be provide either reference for constructing newdevice to produce KA oil through oxidizing cyclohexane without catalystor scientific basis for technical innovation of the existed industrialprocesses.This study mainly investigated the effects of reactant feed ratio,reaction temperature and reaction time, etc, on cyclohexane oxidation andCHHP decomposition. The following conclusions can be obtained.(1) Innoncatalytic cyclohexane oxidation process, when using air oxidant, thecontent of by-product monoacid would be higher in the product. While thecontent of organics which can be conversion and recovery is higher.(2)The technological conditions of two methods to decompose CHHP arealmost same. The oxidation method does not affect the conversion ratio ofCHHP.(3) The conversion ratio of CHHP through acid decomposition(Chromic acid (H2CrO4),bis (1,1-dimethylethyl) ester) is higher than that ofalkaline decomposition (cobalt acetate). The ratio of cyclohexanol/cyclohexanone in the decomposition product is about2:3,that is the content of cyclohexanol is higher than that of cyclohexanone.(4)In the process of alkaline saponification decomposition using cobalt acetatecatalyst, although it consumes large caustic alkali and also produces muchalkali waste liquid, the scaling problem specially in downstream process ofrefining cyclohexanol and cyclohexanone is greatly mitigated than the aciddecomposition process which is used chromic acid (H2CrO4),bis(1,1-dimethylethyl) ester catalyst.(5) If the water washing unit operationin DSM technological process is moved before CHHP decomposition unitoperation, then it will reduce the alkali consumption during CHHPdecomposition. Furthermore, it will benefit on recovering by-productsproduced in cyclohexane oxidation and those by-products can be convertedinto C4-6dibasic acid.