Mitsui Toatsu Chemicals, Incorporated

Yoshitsugu Kono

Hiroyuki Itoh

Shinji Takenaka

Masanobu Ajioka

Isao Kikuchi

Ryoichi Taneda

Teruyuki Nagata

Akihiro Tamaki

Katsuji Watanabe

Masafumi Kataita

Takashi Kobayashi

Mitsuo Kudoh

Usaji Takaki

Ryuichi Mita

Yukihiro Yoshikawa

Mitsumasa Umemoto

Masaaki Ura

Teruo Hirayama

Hiroshi Maeda

Satoshi Tsuruda

Hiroshi Ichiki

Tsugio Watanabe

A process for the continuous preparation of aniline by hydrogenating nitrobenzene with hydrogen is disclosed which comprises the steps of suspending, in an aniline solvent, a catalyst of palladium or palladium-platinum which is deposited on a lipophilic carbon having an oil absorbency of at least 100, and carrying out reaction at a temperature of from 150.degree. to 250.degree. C. substantially in the absence of water while aniline and water formed in said reaction are continuously distilled off as vapor from the reaction product, and the concentration of nitrobenzene in the reaction solution is maintained at 0.01% by weight or less, wherein a zinc compound is added to the reaction system as a promotor and carbon monoxide is added to the hydrogen at a concentration of 1-500 ppm.

Process for preparing high-purity aniline

Disclosed herein is a crystallization apparatus for use in the crystallization of L-.alpha.-aspartyl-L-phenylalanine methyl ester. The stirring blade of the crystallization apparatus is composed of a band plate member for sweeping the bottom of a vessel and rod- or band plate-members arranged thereon and extending substantially vertically and horizontally.

Process for the crystallizing L-.alpha.-aspartyl-L-phenylalanine methyl

Concentration process of gaseous chlorine

A method and an apparatus for concentrating/purifying a chlorine gas are disclosed in which a pressure swing adsorption method for alternately repeating an adsorbing operation and a desorbing operation employing one or more adsorption towers packed with an adsorbent for adsorbing the chlorine gas are used to obtain a high-purity concentrated/purified chlorine gas and an exhaust gas containing virtually no chlorine gas is obtained from the chlorine gas containing impurities by terminating the adsorption operation when the rate of temperature rise near the outlet end of an adsorption tower due to adsorption of chlorine therein rises above a predetermined amount.

Method and apparatus for concentrating chlorine gas

A process for the continuous preparation of aniline by hydrogenating nitrobenzene is disclosed which comprises the steps of suspending, in an aniline solvent, a catalyst of palladium or palladium-platinum which is deposited on a lipophilic carbon having an oil absorbency of at least 100, adding a zinc compound and an alkali metal carbonate or a zinc compound and an alkali metal bicarbonate as promotors to the reaction system, and carrying out reaction at a temperature of from 150 to 250.degree. C. substantially in the absence of water while aniline and water formed in said reaction are continuously distilled off as vapor from the reaction product, and the concentration of nitrobenzene in the reaction solution is maintained at 0.01% by weight or less.

A gaseous mixture containing chlorine, carbon dioxide and non-condensable gas is compressed and cooled to separate it into a residual gas formed principally of a major portion of the non-condensable gas and a condensate formed primarily of chlorine. The condensate is fed to a stripping column to desorb carbon dioxide and a minor portion of the non-condensable gas dissolved in the condensate. The stripped gas formed primarily of chlorine and carbon dioxide may be treated further. Namely, the stripped gas is mixed with the residual gas. At least a portion of the mixed gas is fed into an absorption column, whereby a major portion of remaining chlorine is absorbed to lower the chlorine content Removal of chlorine from such a gaseous mixture or an off-gas from the above process can be achieved by washing it with an aqueous solution or suspension containing an alkali metal sulfite and/or an alkaline earth metal sulfite while controlling the pH of the solution or suspension within a range of 1.9-6.3.

Industrial process for the separation and recovery of chlorine

There is here disclosed a method for obtaining high-purity cinnamic acid containing less metals from crude cinnamic acid containing a metallic catalyst which is a mixture prepared by the synthetic reaction of a cinnamic acid ester. A disclosed purifying means is the combination of alkali hydrolysis, active carbon adsorption, solvent extraction and precipitation with an acid.

Method for obtaining high-purity cinnamic acid

Chlorine is produced by reacting hydrogen chloride and oxygen in the presence of a catalyst composed of a chromium oxide as a principal component. The reaction is carried out in a fluidized bed reactor equipped at vertical intervals not greater than 100 cm with a plurality of perforated horizontal plates having a perforation rate of 10-60% in a reaction zone in which the catalyst is fluidized in operation. The reaction zone is above a gas diffuser plate.

Production process of chlorine

Crude pentachloronitrobenzene containing hexachlorobenzene and small amounts of acids is treated in the molten state or in a mixture solution of nitrobenzene or chloronitrobenzenes with an inorganic basic substance and then subjected to a distillation under reduced pressure.

Method for purifying pentachloronitrobenzene by solid base treatment

A process for purifying tryptophan is disclosed. In the process of the present invention, tryptophan is recrystallized in water-containing acetic acid. By the process of the present invention, tryptophan with high purity may be obtained with high yield without condensation or neutralization.

Process for purifying tryptophan

A gaseous mixture containing chlorine, carbon dioxide and non-condensable gas is compressed and cooled to separate it into a residual gas formed principally of a major portion of the non-condensable gas and a condensate formed primarily of chlorine. The condensate is fed to a stripping column to desorb carbon dioxide and a minor portion of the non-condensable gas dissolved in the condensate. The stripped gas formed primarily of chlorine and carbon dioxide may be treated further. Namely, the stripped gas is mixed with the residual gas. At least a portion of the mixed gas is fed into an absorption column, whereby a major portion of remaining chlorine is absorbed to lower the chlorine content. Removal of chlorine from such a gaseous mixture or an off-gas from the above process can be achieved by washing it with an aqueous solution or suspension containing an alkali metal sulfite and/or an alkaline earth metal sulfite while controlling the pH of the solution or suspension within a range of 1.9-6.3.

An improved process is provided for the production of chlorine. In a fluidized-bed reactor having a specific equivalent diameter and made of a material with a particular iron content, hydrogen chloride and oxygen are reacted in particular gas volumes and at specific molar ratio, superficial velocity, temperature and pressure in the presence of a catalyst composed principally of a chromium oxide and having a specific particle size distribution. The catalyst is filled in a specific amount in terms of catalyst layer height at rest. The catalyst can retain its high activity.

Chlorine is produced by oxidizing byproduced hydrogen chloride. An offgas containing hydrogen chloride as a byproduct is reacted with oxygen at 300.degree.-500.degree. C. in the presence of a catalyst which contains chromic oxide (Cr.sub.2 O.sub.3) as a principal component. The resulting gas is cooled rapidly and then washed with water to recover vaporized chromium. The hydrogen chloride is then absorbed in water to recover it as an aqueous hydrochloric acid solution. The still remaining portion of the resultant gas is washed with sulfuric acid to remove water from the same, followed by compression and cooling. The resulting liquefied chlorine is separated. The still remaining gas composed principally of oxygen is thereafter returned to the oxidation step.

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Omuta, Japan

Yoshitsugu Kono