Mitsui Toatsu Chemicals, Incorporated

Hiroyuki Itoh

Yoshitsugu Kono

Shinji Takenaka

Masanobu Ajioka

Masafumi Kataita

Isao Kikuchi

Yoshitsugu Kohno

Ryoichi Taneda

Mitsuo Kudoh

Masahiro Ohta

Yasunori Yoshida

Usaji Takaki

Shoji Obuchi

Yukihiro Yoshikawa

Masaaki Ura

Mineo Kobayashi

Teruo Hirayama

Noritoshi Ishida

Zunzi Tashima

Takashi Nagou

Katsuyuki Nagamatsu

Tsugio Watanabe

Satoshi Tsuruda

Naoyuki Yano

Fumiaki Ichikawa

Tatsuya Nagayoshi

Hiroshi Ichiki

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

A process for preparing polyhydroxycarboxylic acid by conducting dehydration polycondensation of hydroxycarboxylic acids in the presence or absence of a catalyst and in the presence or absence of an organic solvent, comprising using a vertical high viscosity reactor during all or a portion of the dehydration polycondensation steps and conducting hot polycondensation while separating and removing low boiling components. The process can provide high molecular weight polyhydroxycarboxylic acid with ease and cheaply in industry.

Process for preparing polyhydroxycarboxylic acid

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 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

Chlorine is produced by reacting hydrogen chloride and oxygen in the presence of a chromium oxide catalyst in a reactor whose catalyst-contacting part is lined with one of lining materials represented by the following general formula (I):

Reactor for the production of chlorine

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 methylene-crosslinked polyarylamine is disclosed which contains a less amount of N-methylmethylenedianiline. A process for continuously preparing this kind of methylene-crosslinked polyarylamine is also revealed which comprises reacting aniline with formalin in the presence of hydrochloric acid under specific reaction conditions.

Methylene-crosslinked polyarylamine and process for preparing same

Chlorine is produced by reacting hydrogen chloride and oxygen in the presence of a chromium oxide catalyst in a reactor whose catalyst-contacting part is lined with one of lining materials represented by the following general formula(I):

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.

Growing community of inventors

Omuta, Japan

Hiroyuki Itoh