Green Technology Research On Synthesizing Phenanthrenequinone

Our province is rich in coal resources and largely produces coke and coal tar every year, and phenanthrene is one of the main components in the coal tar, the development and utilization of the phenanthrene have always being researched in coal chemical engineering field. So far, many ways of phenanthrene utilization have already been proposed, in which the making of phenanthrenequinone oxidated by phenanthrene is one of important directions. Phenanthrenequinone is the important intermediate with extensive applications, the synthesizing phenanthrenequinone from phenanthrene has considerable ceconomical value. Although there are many methods of synthesizing phenanthrenequinone, at present, the industry massive production have not come true because of the technic, cost, pollution and so on. In view of many problems of phenanthrenequinone synthesis, a new phenanthrenequinone synthesis technology with low cost and no pollution is determined as the research topic of this thesis.In this paper, industrial phenanthrene was used as raw material, dichromate as oxidant, water as medium, quaternary ammonium salt as phase transfer catalyst, phenanthrenequinone synthesis was researched by liquidphase catalysis oxidation in the acid medium. The four aspects studied in the paper are as follows: first, the optimal oxidant and the optimal catalyst were selected. Second, through homogeneous design, how the factors influence on phenanthrenequinone yield was got known, such as the amount of oxidant, the amount of catalyst, the solution acidity, reaction time and temperature, the best condition of phenanthrenequinone synthesis was found. Third, the analysis methods of the mother liquor major components were established: redox titration of determining the content of chromium; potentiometric titration of the acidity, because trivalence chromium ions have serious interference, the sodium hexametaphosphate was added to eliminate the interference. Fourth, under the best conditions, the experiments of many times mother liquor recycling utilization and trivalence chromium by-product reclaim were undergone. The experiment showed: mother liquor became slabbier and slabbier with its recycling utilization times increasing; basing on analyzing the factors leading to mother liquor slabbier, the solution of mother liquor extraction-crystallization was proposed.The results show: when potassium dichromate is used as oxidant, the by-product is easily separated from the mother liquor, and the circulation and utilization of mother liquor can go along; dodecyl tyimethyl ammonium chloride is the best phase transfer catalyst among the catalysts used in experiments; there are major effect of the liquor acidity and the oxidant amount on phenanthrenequinone yield; the mother liquor viscosity is the key which limits times of mother liquor circulation utilization, the viscosity can be reduced by extraction- crystallization and the trivalent chromium by-product can be crystaled out, and mother liquor circulation utilization can go along; Under the optimum conditions, the yield of phenanthrenequinone is high to 80 percent or more each recycle; the by-product is determined as dodecahydrated potassium chromium sulfate by the XRD; it is very difficult to make certain acidity in mother liquor with lots of Cr²⁺ by potentiometric titration, Cr³⁺ interfere can be eliminated by adding sodium hexametaphosphates into mother liquor, and acidity of mother liquor can be determined accurately.In a word, the green technology of phenanthrenequinone synthesis has many advantages, such as the mild reaction conditions, low cost, feasible circulation utilization of mother liquor, no pollution, and easy recovery of the by-product and so on. So it has broad industrialization prospects.