Process, technology oxidation

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

Butane-Based Fixed-Bed Process Technology. Maleic anhydride is produced by reaction of butane with oxygen using the vanadium phosphoms oxide heterogeneous catalyst discussed earlier. The butane oxidation reaction to produce maleic anhydride is very exothermic. The main reaction by-products are carbon monoxide and carbon dioxide. Stoichiometries and heats of reaction for the three principal reactions are as follows ... 

Butane-Based Transport-Bed Process Technology. Du Pont aimounced the commercialization of a moving-bed recycle-based technology for the oxidation of butane to maleic anhydride (109,149). Athough maleic anhydride is produced in the reaction section of the process and could be recovered, it is not a direct product of the process. Maleic anhydride is recovered as aqueous maleic acid for hydrogenation to tetrahydrofuran [109-99-9] (THF). 

An important future use for maleic anhydride is beUeved to be the production of products in the 1,4-butanediol—y-butyrolactone—tetrahydrofuran family. Davy Process Technology has commercialized a process (93) for producing 1,4-butanediol from maleic anhydride. This technology can be used to produce the product mix of the three molecules as needed by the producer. Another significant effort in this area is the tetrahydrofuran plant under constmction in Spain by Du Pont in which butane is oxidized and recovered as maleic acid and the maleic acid is then reduced to tetrahydrofuran (109). 

Industrially, vitamin is prepared from the chromic acid oxidation of 2-methylnaphthalene (56). Although the yields are low, the process is economical owing to the low cost and availabiUty of the starting material and the oxidizing agent. However, the process is compHcated by the formation of isomeric 6-meth5l-l,4-naphthoquinone. As a result, efforts have been directed to develop process technology to faciUtate the separation of the isomeric naphthoquinone and to improve selectivity of the oxidation. 

Air-Based Direct Oxidation Process. A schematic flow diagram of the air-based ethylene oxide process is shown in Figure 2. Pubhshed information on the detailed evolution of commercial ethylene oxide processes is very scanty, and Figure 2 does not necessarily correspond to the actual equipment or process employed in any modem ethylene oxide plant. Precise information regarding process technology is proprietary. However, Figure 2 does illustrate all the saUent concepts involved in the manufacturing process. The process can be conveniently divided into three primary sections reaction system, oxide recovery, and oxide purification. 

Process Technology Considerations. Innumerable complex and interacting factors ultimately determine the success or failure of a given ethylene oxide process. Those aspects of process technology that are common to both the air- and oxygen-based systems are reviewed below, along with some of the primary differences. 

DeFine a process technology developed by UOP Corporation for reducing the level of dienes in an olefin stream EO ethylene oxide... 

The first study on the oxidation of arylmethanes used this reaction as a model to show the general advantages of electrochemical micro processing and to prove the feasibility of an at this time newly developed reactor concept [69]. Several limits of current electrochemical process technology hindered its widespread use in synthetic chemistry [69]. As one major drawback, electrochemical cells stiU suffer from inhomogeneities of the electric field. In addition, heat is released and large contents of electrolyte are needed that have to be separated from the product. 

Adamska-Rutkowska, D., 1992, An Identification of the Model of the Process for Oxidation of Benzene to Maleic Anhydride , Ph.D. Thesis, Warsaw University of Technology, Warsaw. 

Ravi, V., Mok, Y.S., Rajanikanth, B.S. et al. (2003) Temperature effect on hydrocarbon-enhanced nitric oxide conversion using a dielectric barrier discharge reactor, Fuel Processing Technology 81, 187-99. 

Villasenor, F. Loera, O. Campero, A., and Viniegra-Gonzalez, G., Oxidation of dibenzothiophene by laccase or hydrogen peroxide and deep desulfurization of diesel fuel by the later. Fuel Processing Technology, 2004. 86(1) pp. 49-59. 

Marzona, M. Pessione, E. Di Martino, S., and Giunta, C., Benzothiophene and dibenzoth-iophene as the sole sulfur source in Acinetobacter growth kinetics and oxidation products. Fuel Processing Technology, 1997. 52(1-3) pp. 199-205. 

Econ-Abator A process for oxidizing hydrogen sulfide and other sulfur compounds in waste gases by fluid bed combustion in the presence of an oxide catalyst. Licensed by ARI Technologies. In 1992 there were 90 installations. 

Other routes. Alternate process technologies for making phenol avoid the cumene route. A few plants have used toluene as a feed, oxidizing it over a cobalt catalyst to give benzoic acid. That is followed by a reduction (removal of oxygen atom) to give phenol and carbon dioxide. 

Miller, R., Advancing Technologies Oxidizers, Polymers, and Processing, Solid Rocket Technical Committee Lecture Series, AlAA Aerospace Sciences Meeting, Nevada, 1994. 

Fuller, C.W. (1974) Iron oxides, synthetics. In Considine, D.M. (ed.) Chemical and process technology encyclopedia. McGraw-Hill Book Company, p. 645... 

Emphasis in CMP technology in 1998-1999 has evolved from a nearly exclusive focus on traditional polish systems to the use in manufacturing of advanced second- and third-generation polishers. This advance in technology has translated into standard CMP processes for oxide, polysilicon, and tungsten CMP, and expanded interest in aluminum CMP, copper CMP,... 

SafeSoil is an ex situ, biostimulation treatment technology that is specifically designed to remediate soil contaminated with organic compounds. The SafeSoil process biologically oxidizes... 

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