Zur Theorie und Praxis der Phosphoroxidation
Based on the theoretically calculated; and on experimentally investigated thermodynamic data of the molecular phosphorus oxides °6 P407, P408, P09 and P010 which are metastable under normal conditions respectively their dissociation products P0, P02, P3, P2, P, .02 and 0, which probably exist under the conditions of hot phosphorus oxidation, thermodynamic calculations yield their equilibrium states in dependence on temperature, pressure and the P:0—ratio. Accordingly there . are characteristic ranges of temperature in which the respective molecular phosphorus oxides at constant total pressure exist only in depextdence..on the P:0—ratio. With increasing total pressure the existence ranges of the pure components extend towards higher temperatures. For instance at a total. pressure of I05 Pa the P406—molecule is stable at the P:02—ratio of 1:3 nearly 2000K. and the P4010—molecule is stable at the .P4 02—ratio of 1:5 up to 1900K. On introducting 00 as an additional component influencing the equilibrium,002 is formed and the equilibrium is changed in the direction of decreasing P:O—rati.o. Above 3500K. no more 002 is present in the equilibrium whereas the molecular phosphorus oxides cease to exist above 2500K. Since at temperatures above 1800K kinetic factors have practically .no effect on. the rate of the equilibrium, the rate of reaction depends only on factors which influence the rate of mixing of gases7 such as the viscosity of the gases. The quenching of the hot phosphorus flame was investigated basing on the theoretical understandings. Depending on the temperature gradient, on the P:O—ratio and on the mean temperature in the reaction zone by a suitable carrying of energy. practically pure normally metastable products may be obtained, if an ideal mixing regime can be approached. As a consequence an alteration of the total pressure effects as well the required temperature gradient of the