Catalytic oxidation processes with

BP Chemicals, Inc. Maleic anhydride n-Butane Fluid-bed catalytic oxidation process with an aqueous-based recovery and purification 3 1994... 

Scheme 5. Upjohn s catalytic dihydroxylation process with 0s04 and 4-methylmorpholine /V-oxide (NMO).

In the late 1950 s two groups - one at ICI (ref. 1) and the other at the Mid-Century Corporation (ref. 2) - independently discovered that p-xylene is oxidized to terephthalic acid in almost quantitative yield when soluble bromides are used together with cobalt and manganese catalysts in acetic acid solvent at temperatures > 130 °C (ref. 3). This discovery formed the basis for what became known as the Mid-Century process and later, when the Mid-Century Corporation was acquired by Amoco, as the Amoco MC process for the commercial production of terephthalic acid. A large part of the ca. 6 million tons of the latter that are manufactured annually, on a worldwide basis, are produced via this method. This makes it the most important catalytic oxidation process (ref. 4). 

Attempts to achieve selective oxidations of hydrocarbons or other compounds when the desired site of attack is remote from an activating functional group are faced with several difficulties. With powerful transition-metal oxidants, the initial oxidation products are almost always more susceptible to oxidation than the starting material. When a hydrocarbon is oxidized, it is likely to be oxidized to a carboxylic acid, with chain cleavage by successive oxidation of alcohol and carbonyl intermediates. There are a few circumstances under which oxidations of hydrocarbons can be synthetically useful processes. One group involves catalytic industrial processes. Much effort has been expended on the development of selective catalytic oxidation processes and several have economic importance. We focus on several reactions that are used on a laboratory scale. 

The discovery of TS-1 and its unique catalytic properties constitutes a significant contribution to the knowledge of silica-based zeolite-like materials containing elements different from Al(III) and opens new technological possibilities for oxidation processes with H2O2. 

Despite their obvious economical and ecological importance, few catalytic systems are available for the transformation of alcohols into aldehydes and ketones, using molecular oxygen or air as the ultimate, stoichiometric oxidant (5). Moreover, most of the currently available catalytic oxidation processes suffer from severe limitations, being usually only effective with reactive alcohols, such as benzylic and allylic ones, or requiring high pressures, temperatures, and catalyst loading. 

Adsorption isotherms play a key role in either the design of the adsorption-based process for the disposal of wastes containing VOCs or modeling the catalytic oxidation process. The equilibrium data for mesoporous sorbents are fitted to combined model of Langmuir and Sips equations. This hybrid isotherm model with four isotherm parameters... 

Heterogeneous catalytic oxidation is a well studied and industrially useful process. Industrial catalytic oxidation of vapors and gases is a very broad field and is dealt with in several texts and review articles. Catalytic oxidation, both partial and complete, is an important process for such reactions as the partial oxidation of ethene and propene, ammoxidation of propene to acrylonitrile, maleic anhydride production, production of sulfuric acid, and oxidation of hydrocarbons in automotive exhaust catalysts. By far, the majority of oxidation catalysts and catalytic oxidation processes have been developed for these industrially important partially oxidized products. However, there are important differences between the commercial processes and the complete catalytic oxidation of VOCs at trace concentrations in air. For instance, in partial oxidation, complete oxidation to CO2 and H2O is an undesirable reaction occurring in parallel or in series to the one of interest. Other differences include the reactant concentration and temperature, the type of catalyst used, and the chemical nature of the oxidizable compound. Approximate ranges of the major independent variables of interest in this review are shown in Table 1. 

In some cases it is necessary to exchange heat with the fluidized bed as, for example, in the catalytic oxidation processes mentioned in the Introduction. Heat may be exchanged with the bed through the wall or through internal heat exdiangers. The data availaUe to date have been correlated and are brkfly mentioned here. Figure 133-6 shows the most complete correlation available for heat... 

Parallel to these developments, observations made in the 19th century linked the deterioration of many organic materials, such as natural oils and fats, to the absorption of dioxygen. Around the turn of the century it was recognized that these processes involved organic peroxide intermediates. Subsequently, detailed mechanistic studies with simple hydrocarbons led to the free radical chain theory of autoxidation [7]. Following close on the heels of these mechanistic developments several important catalytic oxidation processes, in both the gas and liquid phase, were developed in the period 1945-1960. Some examples are shown in Table 1. 

Also for oxidation reactions, the choice of the alumina support mainly depends on two criteria the stability of the phase at the reaction temperature and the reactivity (or better the lack thereof) toward feed components and products. For example, ethylene oxychlorination to ethylenedichloride is performed at approximately 220-250° C and 5-6 atm in the presence of a y-Al203-supported catalyst, which has a surface area of from 100 to 200 m and contains 10wt% CUCI2 and 3 wt% KCl, (423,424). Another example is a process called ammonia selective oxidation (ASO, or also selective catalytic oxidation, SCO), which converts small amounts of NH3 from waste gases to N2 at reaction temperatures of 150—300 °C. The process is used to abate the ammonia sHp after a selective catalytic reduction process with ammonia or urea in diesel-engine-exhaust after-treatment (425). The patented catalyst consists of Y-AI2O3 (60—300 m g ) loaded with 0.5-4 wt% platinum and 0.5—4 wt% vanadia and is coated onto the surface of a ceramic or metallic monoftthic structure (426). 

Three types of catalytic oxidation processes can occur, each with a unique mechanism (7). These are ... 

These catalytic oxidation processes are utilized frequently in the manufacture of fine chemicals. Sheldon speculates that future technologies will focus on these processes for the synthesis of chemicals because of their utility and compatibility with environmental mandates (7). 

A catalytic oxidation process is going to be carried out in a fluidized bed with spherical catalyst particles. Calculate all the parameters of oxygen needed for the Kunii-Levenspiel model, starting from the physical data given below ... 

Catalytic oxidation processes are usually connected with transfer of electrons and changes of structure and valence state of active catalyst components. This chapter presents methods that are especially suitable for monitoring these kinds of changes (UV-vis-DRS, EPR, X-ray scattering, XPS, XAS, TPO, TPR, TPRS, TAP and SSITKA). After a short section on basic principles and experimental details, the potential of each technique is illustrated by selected application examples that include a wide variety of oxidation catalysts such as mixed metal oxides and oxynitrides, zeolites containing transition metal ions, heteropoly acids and supported noble metals. 

At the moment, selective oxidation of -butane to MA is the only catalytic oxidation process employing a light alkane as the feedstock which has been fully established at an industrial level. It must be indicated that surprisingly the results from the -butane process (MA yield around 80%, with selectivity of 60%) are better than those obtained from butenes. This fact has encouraged the scientific community to study similar catalytic reactions with other alkanes. Thus, other successful processes could be developed by using the appropriate catalyst, optimal reaction conditions, and an improved reactor technology. 

A detailed account of the mechanisms of catalytic oxidation processes has been published. The mechanisms of the catalytic oxidation of terminal oleffns to methyl ketones and of the catalytic epoxidation of olefins with hydroperoxides have also been reviewed. The latter reactions are generally thought to proceed via direct attack of the substrate upon an electrophilic oxygen of a metal peroxo species rather than prior complexa-... 

A two-stage cyclic fluidized bed process for converting HCl to chlorine is described in [204]. The catalytic oxidation process combines the exothermic oxidation of 60 - 70 % of the HCl at 380-400 C in a fluidized bed of copper oxychlorides impregnated on zeolite with the transfer of the reaction products to a second reactor operating at 180-200 °C where the rest of HCl is converted. 

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