Nippon Shokubai Co., Ltd.

Yasuhisa Emoto

Tsukasa Takahashi

Kenji Ueda

Masaaki Okuno

Tatsuya Kawabata

Toshio Sagane

Etsushige Matsunami

Yasushi Kiyooka

Process for producing pyromellitic anhydride

Provided is a process for producing pyromellitic dianhydride by feeding 1,2,4,5-tetraalkylbenzene to a fixed bed multitubular type reactor charged with a catalyst layer to carry out catalytic vapor phase oxidation. This process is characterized by dividing the catalyst layer into at least two layers to charge a layer at an outlet side of reaction gas and a layer at an inlet side of raw material mixed gas with the following catalyst A and catalyst B respectively or dividing the catalyst layer into at least three layers to charge a layer at an outlet side of reaction gas, an intermediate layer and a layer at an inlet side of raw material mixed gas with the following catalyst A, catalyst B and catalyst C respectively:

Production process for pyromellitic dianhydride

A method for the production of fluorenone for the vapor-phase catalytic oxidation of fluorene with a molecular oxygen-containing gas, which including adjusting the molar ratio of fluorene to molecular oxygen in a feed raw material gas composed of fluorene as a raw material and a molecular oxygen-containing gas in the range of 1:1 to 0.13:1, or keeping the sulfur content in a raw material fluorene at or below 0.15% by weight.

Method for production of fluorenone

A catalyst for obtaining pyromellitic anhydride at a high raw material gas concentration with high yield and a method for the production of pyromellitic anhydride are provided. The catalyst containing vanadium and silver as essential component elements for catalyst and having an atomic ratio of silver to vanadium in the range of from 0.001 to 0.2 allows efficient production of pyromellitic anhydride by the vapor-phase oxidation of a tetraalkylbenzene with a molecular oxygen-containing gas. The method of this invention accomplishes the production of pyromellitic anhydride by the use of the catalyst.

Catalyst for production of pyromellitic anhydride and method for

A method for producing efficiently on a commercial scale pyromellitic anhydride having high purity and suffering only sparing coloration in a high yield from a raw material of high concentration is provided. By the use of a multilayer catalyst formed by packing on the reaction gas outlet side a first catalyst containing V and Mo and/or W and having an atomic ratio of Mo and/or W to V in the range of from 0.01 to 2, on the raw material mixed gas inlet side a second catalyst containing V, Mo and/or W and having an atomic ratio of Mo and/or W to V smaller than the atomic ratio of the first catalyst, and/or a third catalyst containing V and an alkali metal and having an atomic ratio of the alkali metal to V in the range of from 0.2 to 2.5, pyromellitic anhydride is produced by the vapor-phase oxidation of a tetraalkyl benzene with a molecular oxygen-containing gas.

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Hyogo, Japan

Yasuhisa Emoto