Abstract: An improved production method of aromatic carboxylic acid products of significantly improved yield and quality by oxidizing alkyl aromatic substrates or their partially oxidized intermediates in a conventional MC-type catalyst system modified to contain additional components such as alkali metal or alkaline earth metal in an acetic acid medium in a feed gas containing oxygen and optionally carbon dioxide. Since carbon dioxide functioned as a co-oxidant along with oxygen in the oxidation reaction, the oxidation reaction proceeds more selectively to produce the carboxylic acid product much faster under milder reaction conditions over the conventional MC-type oxidation. In particular, the oxidation of para-xylene carried out by the novel present method enabled production of terephthalic acid of higher yield and enhanced quality, which were improved far more than the extent that generally could be expected by current PTA producers.

Abstract: An improved production method of aromatic carboxylic acid products of significantly improved yield and quality, the method including oxidizing alkyl aromatic substrates or their partially oxidized intermediates in a catalyst system containing a conventional catalyst and, if deemed necessary, additional components such as a transition metal or lanthanide series metal, in an acetic acid medium, with a feed gas containing both oxygen and carbon dioxide. Since carbon dioxide functions as a co-oxidant along with oxygen in the oxidation reaction, the oxidation reaction proceeds more selectively to produce the carboxylic acid product much faster under milder reaction conditions as compared to the conventional oxidation.

Abstract: An improved production method of aromatic carboxylic acids of significantly improved yields and quality by oxidizing alkyl aromatic substrates or their partially oxidized intermediates by oxygen-enriched gas in a conventional Co—Mn—Br catalyst system containing additional components such as a transition metal or lanthanide metal component in an aliphatic carboxylic acid having 1˜6 carbon atoms. In other words, a decline in reactivity in the later part of the oxidation reaction and the precipitation of a catalyst such as manganese were effectively deterred by means of incorporating one or more than one type of transition or lanthanide metal components selected from such metals as Ce, Zr, Hf, Fe, Cr, and Mo during the oxidation reaction with oxygen-enriched gas. With this invention, pure aromatic carboxylic acids with white color can be obtained with high selectivity and reactivity by oxidation of substrates with oxygen-enriched gas.