Samsung General Chemicals, Co., Ltd.

Samsung General Chemical Co., Ltd.

Ki-Hwa Lee

Jin S Yoo

Youn-Seok Park

Sung-Hwa Jhung

Jin-Sun Yoo

Jong-Hyun Chae

The present invention relates to a preparation method of methacrylic acid which improves reaction selectivity of methacrylic acid. The method may include producing methacrylic acid by gas phase oxidation of methachrolane in the presence of catalyst. Particularly, the present invention relates to the preparation method of methacrylic acid comprising the step of introducing COup to 3&#x2dc;80 mole % of the feed gas in the presence off catalyst having the general formula of PMoVXYO. X may be one or more elements selected from the group of alkaline metal and Tl element. Y may be one or more elements selected from the group of Cu, Pb, Sb, Cr and Ce. In addition, a, b, c, d and e are the molar ratio of each necessary element when molybdenum is 11; where a is 0.8&#x2dc;1.6, b is 0.6&#x2dc;2, c is 0.8&#x2dc;2.2, d is 0.1&#x2dc;0.8 and e is a suitable value for elemental valency in the composition of said formula respectively.

Preparation method of methacrylic acid

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. The present invention also provides an effective purification process to produce highly pure terephthalic acid or isophthalic acid by the oxidation of impurities such as 4-carboxybenzaldehyde and para-toluic acid or 3-carboxybenzaldehyde and meta-toluic acid contaminated in crude terephthalic acid and isophthalic acid product, respectively.

Method of producing aromatic carboxylic acids by oxidizing alkyl aromatic hydrocarbons or partially oxidized intermediates thereof

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. The present invention also can be utilized as an effective purification process to produce highly pure terephthalic acid or isophthalic acid by oxidation of impurities such as 4-carboxybenzaldehyde and para-toluic acid or 3-carboxybenzaldehyde and meta-toluic acid which are contaminated in crude terephthalic acid and isophthalic acid products, respectively.

Method of producing aromatic carboxylic acids by oxidizing alkyl aromatic compounds or partially oxidized intermediates thereof with carbon dioxide containing gas

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Taejeon-shi, South Korea

Ki-Hwa Lee