Engineering Aspects of Industrial Liquid-Phase Air Oxidation of Hydrocarbons

Abstract

Liquid-phase air oxidation of hydrocarbons, notably p-xylene, cumene, ethylbenzene/isobutane, cyclohexane, and n-butane, is of great scientific, technological, and commercial importance. This state-of-the-art paper covers the chemistry and engineering science aspects of these reactions. The role of uncatalyzed reactions and metal ion and mixed metal ion catalysts with bromide activation is discussed. An analysis is presented for the role of mass transfer in influencing the rate of reaction and selectivity for the desired product. Different types of reactors that are used, notably bubble-column reactors and mechanically agitated reactors, are analyzed, and a simple basis is provided for selection of reactors. Some emerging oxidation systems, notably oxidation of cycloalkenes (cyclohexene/cyclooctene/cyclododecene) and oxidation of isobutane under supercritical conditions, are presented. New strategies for conducting air oxidations, such as in biphasic systems (including fluorous biphasic systems), biocatalysis, photocatalysis, etc., are emerging and illustrate the considerable tailoring of the reaction microenvironment that is becoming possible. In some cases, it may be possible to manipulate chemo-, regio-, and enantioselectivity in these reactions.

Catalytic oxygen activation versus autoxidation for industrial applications: a physicochemical approach

“…In particular, there is a strong demand for: (i) catalysts capable of energy and cost effective processes with increased selectivity, and (ii) oxidation routes using air or molecular oxygen as the ultimate oxidant. 30,31 At present, a common route to drive selective oxidation by transition metals is to modify the oxidation state of the catalytically active metal centre. [32][33][34][35] However, the diradical nature of molecular oxygen means that it can also react with organic substrates via autoxidation pathways.…”

Characterization of metal-containing molecular sieves and their catalytic properties in the selective oxidation of cyclohexane

“…Catalytic partial oxidations of hydrocarbons using oxygen or air as oxidant are significant and economical to the chemical industry [1,2]. Among various alkanes oxidation, the selective oxidation of cyclohexane is much attractive because its products are the intermediates for the manufacture of Nylon-6 and Nylon-6-6 [3].…”

Aerobic Catalytic Oxidation of Cyclohexene over TiZrCo Catalysts

“…However, the selectivity to 2-cyclohexen-1-one decreased linearly due to deep oxidation of 2-cyclohexen-1-one to undesired byproducts at a higher conversion. The aerobic oxidation of cyclohexene is a radical reaction; it contains the chain-initiation, -propagation and -termination steps [1]. The produced radical in the initial step could promote the following steps and was more efficient at higher cyclohexene concentrations as it enhanced the impact probability of radicals, resulting in an increase of the conversion of cyclohexene.…”

“…The selective oxidation of hydrocarbon is of great importance in the chemical industry, and the oxidation of alkenes to value-added chemicals has been paid more attention [1][2][3][4]. For example, 2-cyclohexen-1-one, which can be produced from oxidation of the C-H bond at the allylic site of cyclohexene, is one of the important fine chemicals because it is widely used in the manufacture of perfumes, pharmaceuticals, dyestuff and agrochemicals [5][6][7].…”