Catalytic oxidation of naphthalene

PHTHALIC ANHYDRIDE PRODUCTION VIA THE CATALYTIC OXIDATION OF NAPHTHALENE IN A FIXED BED REACTOR... 

Either naphthalene or ortho-xylene is an acceptable starting material for partial oxidation to phthalic anhydride, but current raw materials costs favor the former as a starting material. Both fixed and fluidized bed processes have been used on a commercial scale, but you are to focus your attention on the former. Figure 13.5 is a schematic flow diagram of the proposed process. Most research groups that have studied the catalytic oxidation of naphthalene over vanadium pentoxide agree that the principal reactions are... 

Phthalic Anhydride Production Via the Catalytic Oxidation of Naphthalene in a Fixed Bed Reactor... 

Heyden-Wacker A process for making phthalic anhydride by the catalytic oxidation of naphthalene or o-xylene. Offered by Lurgi. 

The main ingredients for the early alkyd resins, namely phthalic anhydride and glycerol, were already quite readily available at the time of their development. At that time, phthalic anhydride was made by catalytic oxidation of naphthalene with sulphuric acid. However, a considerable boost to the competitiveness of alkyds was the development from about 1917 of a much cheaper process for phthalic anhydride, based on catalytic vapour-phase oxidation of naphthalene. 

All of the preceding work was for simple, or one step, reactions. The more interesting case of multiple reactions has been studied by de Maria et al. (D15) and by Tichacek (T7). de Maria et al. considered the catalytic oxidation of naphthalene. They found that the consideration of the dispersion effects enabled them to obtain a better design. Tichacek considered the selectivity for several different types of reactions. Naturally, the results were rather complicated, and the statement of general conclusions is rather diflBcult. For small values of the reactor dispersion group, Dl/uL < 0.05, it was found that the fractional decrease in the maximum amount of intermediate formed is closely approximated by the value of Dl/uL itself. For other ranges of the parameters, we refer to the original work (T7). 

The catalytic oxidation of naphthalene can easily be carried out in the laboratory, although the amount of phthalic anhydride which can be prepared in one operation is insignificant. It is of great importance that the correct temperature be maintained and that a suitable catalyst be used. Special attention must be given to the apparatus if the preparation in the laboratory is to succeed. Furthermore, it is highly desirable to use a Cottrel precipitator to collect the reaction product completely. This apparatus will collect even the fine particles, which otherwise would be lost. 

Catalytic oxidation of naphthalene to phthalic anhydride is the seccxid application of FCB which was initiated in 1945. Riley (R12) reported problems on afterburning and on the control of bed temperature, and introduced many improvements in the fluidized bed. However, the most important change to make scale-up easier and to achieve good performance was the use of microspherical catalyst, or moderately active German-type catalyst (Bll, G14). 

Cooling the exit gases causes condensation and crystallization of phthalic anhydride, which is collected and recrystallized to yield >99.5% pure product (about 75% yield). Phthalic anhydride is also made by catalytic oxidation of naphthalene with air. 

The vapor phase catalytic oxidation of naphthalene results in the formation of naphthoquinone, phthalic anhydride, phthalic acid, maleic anhydride, benzoic acid, carbon dioxide, water, etc. Commercially, phthalic anhydride is the most important of these products and the oxidations are so conducted as to yield the largest possible quantity of the substance in as pure a condition as possible. 

Production of phthalic anhydride by the catalytic oxidation of naphthalene in 1928 was the highest on record—6,030,854 pounds.1 In 1929 this production rose to 9,168,946 pounds and in 1930 dropped 27 per cent to 6,693,001 pounds.10 The price of phthalic anhydride has dropped steadily from 4.23 per pound in 1917 to 20 cents in 1925, and to 16.3 cents in 1928. The price in 1930 was quoted as 18 cents in barrel lots. 

Catalysts. The non-catalytic oxidation of naphthalene either in the liquid phase under pressure or in the vapor phase at atmospheric pressure, results in the formation of complete combustion products if temperatures high enough to give good reaction rates are used or else results in die formation of complex tars by condensations and polymerizations of intermediates if such low temperatures are used as to necessitate the use of long times of contact to obtain appreciable reaction. Hence, to obtain valuable products from the oxidation in commercial yields it is essential that catalysts be used. 

Removal of heat from the reaction. In the vapor phase catalytic oxidation of naphthalene to phthalic anhydride, the heat of reaction is so great that unless it is rapidly and thoroughly dissipated the temperature of the catalyst mass rises to a point where complete combustion only occurs. Further, there is a tendency for the pentoxide of vanadium to be reduced to lower oxides at the high temperatures used, particularly if the oxygen supply is limited. These lower oxides tend to combine with the phthalic anhydride and subsequently decompose to destroy the anhydride, so that simple limitations of the oxygen supply to prevent further oxidation of the hydrocarbon is not effective. 

As is done in the case of the atmospheric pressure, catalytic oxidation of naphthalene to phthalic anhydride, a liquid boiling at the reaction temperature may be used to remove reaction heat as latent heat. 

Phthalates are obtained from phthalic anhydride. Phthalic anhydride is a product of catalytic oxidation of naphthalene and o-xylene ... 

Consider, for example, the catalytic oxidation of naphthalene N. On certain solid catalysts, phthalic anhydride P is a major product while on other catalysts important quantities of naphthoquinone Q, are produced. In all cases, a certain quantity of maleic anhydride M also appears as well as gaseous products G of complete oxidation, CO, CO2, and H2O. 

The Cindu Phthalic Anhydride Plant, Uithoorn, Holland Nearly 300 tons of steel was used in 1961 to construct this facility, which consists of a distillation plant and an oxidation plant. Phthalic anhydride is made by catalytic oxidation of naphthalene or orthoxylene. Therefore, the atmosphere in and around the open steelwork of the plant is polluted by steam vapors, phenol, naphthalene, and acid phthalic anhydride, together with sulfur dioxide from oil burners. Some of the resinous residues, however, have a certain protective action on limited areas (e.g., around valves, vents, and resin sprayers). 

Bampenrat, A., Meeyoo, V., Kitiyanan, B., et al. (2008). Catalytic oxidation of naphthalene over Ce02-Zr02 mixed oxide catalysts, Catal. Comm., 9, pp. 2349-2352. 

A review of the work up to 1920 was produced by Weiss and Downs/ of the Barrett Company, who were among the first to investigate the catalytic oxidation of naphthalene. Weiss remained an active consultant until at least 1946. 

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