Abstract: This invention relates to methods and devices of preparing acids, such as adipic acid for example, by oxidizing a hydrocarbon, such as cyclohexane for example, with a gas containing an oxidant, preferably oxygen. A respective hydrocarbon is reacted, preferably at a steady state, with a gaseous oxidant to form an acid in a liquid mixture which preferably contains a solvent, a catalyst, water, and an initiator. The ratio of solvent to hydrocarbon may be controlled in a manner to maintain in the reaction zone maximum reaction rate and/or reactivity, or reaction rate and/or reactivity within a desired range, or reaction rate and/or reactivity directed toward a desired range. In addition, the ratio of solvent to hydrocarbon is controlled in a manner to maintain in the reaction zone substantially maximum selectivity and/or yield, or selectivity and/or yield within a desired range, or selectivity and/or yield directed toward a desired range.

Abstract: Methods and devices for controlling the oxidation of a hydrocarbon to an acid by regulating the temperature hold-up time, and conversion in consecutive reaction zones. The temperature in the consecutive reaction zones progressively decreases, while the hold-up time increases. Preferably, the conversion also increases. One of the major advantages of the methods and devices of the present invention is that an outstanding balance between productivity and selectivity/yield of the desired acid may be achieved. In this respect high yields and selectivities may be obtained without sacrificing productivity.