Phthalic anhydride synthesis

Foster et al.90 studied the role of alkali metal additives on Si02 supported catalysts and observed decreasing activity and surface area together with increasing selectivity with increasing atomic number of the alkali metal. No explanation in simple terms could be given for these effects. Westerman et al.91 observed that a sharply defined level of S03 in the reaction mixture is1 needed to obtain optimum activity in naphthalene oxidation and that the selectivity was not influenced by the S03 level. 

Grabowski et al.92 found that for V205/Ti02 catalysts the maximum selectivity for oxidation of o-xylene to phthalic anhydride was obtained at not too high vanadium contents of 2 to 15 wt% and at temperatures around 350°C. 

Hauffe and Raveling95 studied the oxidation of o-xylene using a number of supports and observed that the best results were obtained with Ti02, followed by Sn02 and Zr02. They explain this on the basis of the influence of the support on the defect structure of the vanadium oxide. 

Grabowski, B. Grzybowska, J. Haber, and J. Sloczynski, React. Kinet. Catal. Lett., 1975, 2, 81. 

Gasior et al.96 studied a number of potassium vanadates which, under reaction conditions decompose to the so-called i//-phase and V6013. The latter is taken to be the active phase being stabilized by the former, because under reaction conditions pure V6013 is oxidized to V2O5. 

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Tasker (1946) Phthalic anhydride synthesis C Air Catalyst on quartz ( ) Granules 1.7-2.0 ... 

Methyl anthraquinone has been obtained by the oxidation of /3-methyl anthracene by several investigators 1 and material of the same origin, obtained by the benzene-extraction of crude commercial anthraquinone,2 has been fully described. As regards the synthesis from phthalic anhydride and toluene, both the preparation and properties of />-toluyl-o-benzoic acid 3 and the complete synthesis 4 have been the subject of several papers. This acid has also been prepared from o-carbomethoxy benzoyl chloride and toluene.5 The phthalic anhydride synthesis of anthraquinone derivatives in general has received considerable attention. An account of this work, together with extensive references, is given by Barnett.6... 

Heat exchange Phthalic anhydride synthesis Uranium processing Coal combustion... 

The classical phthalic anhydride synthesis is not useful for the synthesis of islandicin. Thus both the benzoylbenzoic acids 9 and 10 on cyclization give exclusively the same anthraquinone 11. 

F ure II.I-I Growth curves of reactor capacity in ammonia and phthalic anhydride synthesis from Froment [148] data from [l]and[6]). 

Better design of reactor internals (e.g., in phthalic anhydride synthesis), improving the rate and uniformity of heat removal by molten salts. 

Figure II.3-6 Multitubular reactor for phthalic anhydride synthesis by o-xylene oxidation from Suter [6]). 

With other very exothermic reactions, such as air oxidation of aromatic hydrocarbons, the number of beds would have to be uneconomically large to limit the temperature increase per bed, so that the multitubular reactor is definitely preferred Cooling the reactor with. he incoming reactant would be insufficient, however, and require too much heat exchanging surface. Such reactors are therefore cooled by means of circulating molten salts which in turn give off their heat to a boiler. The phthalic anhydride synthesis reactor shown in Fig. 11.3-6 [6] may contain up to 10,000 tubes of 2.5 cm inside diameter. The tube diameter has to limited to such a small value to avoid excessive overtemperatures on the axis, a feature that is discussed later in this chapter. 

In industrial operation it is necessary, for economic reasons, to recover as much as possible the heat produced by exothermic reactions. One obvious way of doing this, mentioned earlier in Section 11.3, is to preheat the feed by means of the reacting fluid and/or the effluent. When the heat of reaction is sufficient to raise the temperature of the feed to such a value that the desired conversion is realized in the reactor without further addition of heat, the operation is called auto-thermic. Some of the most important industrial reactions like ammonia and methanol synthesis, SO2 oxidation, and phthalic anhydride synthesis, the water gas shift reaction can be carried out in an autothermic way. Coupling the reactor with a heat exchanger for the feed and the reacting fluid or the effluent leads to some special features that require detailed discussion. 

Papageorgiou, J.N. and Froment, G.F. (1996) Phthalic anhydride synthesis. Reactor optimization aspects. Chem. Eng. Sci., 10, 2091-2098. 

Today s fixed bed reactors are mainly large-capacity units. Between 1950 and 1970 the capacity of phthalic anhydride synthesis reactors increased from... 

Papageorgiou and Froment applied this model to the phthalic anhydride synthesis, discussed under Section 11.7.5. The Figs. 11.10-1(a) and (b) show the radial conversion and temperature profiles at a given axial distance in the... 

Pyle [1972] has compared several of these models, as is shown in Fig. 13.5.3-3. Johnsson et al. [1987] compared various bubbling bed models for the simulation of an industrial phthalic anhydride synthesis reactor. Simulation models have been extended to account for the flow of gas in the form of jets in the grid region [Behie and Kehoe, 1973 Grace and de Lasa, 1978]. The flow of solids in the freeboard region above the bed and prior to the cyclones was also studied [George and Grace, 1978]. 

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