| This investigation relates to a method of producing terephthalic acid(TPA) from coal, including oxidation of coal for producing coal acids, followed by isomerization of the coal acids. Huolinhe lignite was subjected to alkali-oxygen oxidation in an aqueous solution of potassium hydroxide, then to make terephthalic acid by isomerization of potassium salt of coal acid in organic dispersant.In order to investigate the formation of aromatic polycarboxylic acids from coals, Huo linhe lignite oxygen-oxidation in aqueous alkali was studied. The coal oxidation was performed in an one-liter autoclave and the initial oxygen pressure, reaction time, reaction temperature and the alkali/coal ratio were changed respectively to study the influence on the yield of coal acids. The highest yield of coal acid under the optimum reaction conditions was 35.21％(daf), which contains 63.97％benzene polycarboxylic acids(BPCA). The theoretical yield of TPA are 68.56％(to BPCA),43.86％(to coal acids) and 15.44％(to coal daf). The optimum actions are: reaction temperature: 240℃, oxygen initial pressure 5.5Mpa, alkali/coal ratio: 3: 1, reaction time: 0.5h.Terephthalic acid can be obtained in the presence of a catalyst Zn(Bzo)2 by isomerization of potassium salt of coal acid(which is a mixture of Huolinhe lignite coal acids, Zazi coal acids and Taxi anthracite coal acids)in organic dispersant have the high boil. The initial CO2 pressure,amount of catalyst,reaction time, reaction temperature and the amount of dispersant were changed respectively to study the influence on the yield of TPA. The optimum conditions of isomerization use biphenyl as the dispersant were: temperature 420℃, initial CO2 pressure 4MPa, catalyst Zn(Bzo)2 3％, dispersant 60％and reaction time 1h, TPA yield 24.1％, with a purity 92％. The optimum conditions of isomerization use p-Terphenyl as the dispersant were: temperature 380℃, initial CO2 pressure 1MPa, catalyst Zn(Bzo)2 3％, dispersant 60％, TPA yield 25.2％, with a purity 94％. The yield of TPA by isomerization a mixture of potassium Salts of coal acid and benzoic acid were 60％, with a purity 93％(use biphenyl as the dispersant)and 62％, with a purity 96％(use p-Terphenyl as the dispersant).The products were analyzed by gas chromatograghy. |
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