Nippon Shokubai Co., Ltd.

Nippon Shokubai Kagaku Kogyo Co., Ltd.

Atochem

Yukihiko Kakimoto

Masayuki Sawada

Yoshihisa Oka

Yoshiaki Kajimoto

Hiroshi Yoshida

Hideaki Tsuneki

Toshio Hayashi

Satoshi Nakagawa

Ritsuo Kitada

Hideyuki Baba

Isamu Kiguchi

Takahiro Inagaki

Kenji Muraoka

Kohei Umehara

Isamu Kiguchi, Deceased

The present invention provides a process for more efficiently producing an &#x3b1;-hydroxycarboxylic acid ester wherein side reactions due to the &#x3b1;-hydroxycarboxylic acid ester are inhibited or prevented in comparison with prior art production processes. The invention provides a process for producing an &#x3b1;-hydroxycarboxylic acid ester comprising Steps 1 to 3: Step 1. reacting, in the presence of oxygen, (i) a 1,2-diol with a 1,2-diol or (ii) a 1,2-diol with an alcohol to obtain a reaction product containing an &#x3b1;-hydroxycarboxylic acid ester; Step 2. separating the &#x3b1;-hydroxycarboxylic acid ester from the reaction product obtained in Step 1 by distillation under reduced pressure; and Step 3. feeding Step 1 with a mixture obtained by partially or entirely removing water from the reaction product, wherein the mixture contains an unreacted 1,2-diol and/or alcohol.

Method for producing &#x3b1;-hydroxycarboxylate

In the case where a carbon steel shell and tube type reactor is used and, for example, ethylene is subjected to catalytic gaseous oxidation to manufacture ethylene oxide, if rust is formed on the internal surface of the tubes, impurities such as aldehydes are formed. The cause of formation of the rust is that when the catalyst in the reactor is exchanged, dew is formed on the internal surface of the tubes. The present invention provides, as a method for preventing the rust formation, a method which comprises, in conducting the catalyst exchange work, maintaining the temperature of the internal surface of the tubes higher than the dew point at the work atmosphere (for example, filling the shell side with water and maintaining the temperature of the water higher than the temperature of the atmosphere).

Method for exchange of catalysts

In a composite process for subjecting ethylene to catalytic gas phase oxidation thereby obtaining ethylene oxide and causing this ethylene oxide to react with water thereby obtaining ethylene glycol, a method for producing the ethylene glycol is provided which permits effective utilization of the energy at the step for dehydrating and concentrating the resultant aqueous ethylene glycol solution. In the production of ethylene glycol by the supply of the aqueous ethylene glycol solution to a concentrating treatment at the multi-effect evaporator, the method contemplated by this invention for the production of ethylene glycol comprises utilizing as the source of heating at least one specific step the steam generated in the multi-effect evaporator.

Method for production of ethylene glycol

The production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with a molecular oxygen-containing gas is effected in a reactor provided with a preheating zone, a reaction zone, a cooling zone, a partition plate separating the first two portions from the third portion, and a multiplicity of reaction tubes piercing the two separated sections by a method which comprises supplying hot water to the cooling zone of the reactor, forwarding zone of the hot water discharged from the cooling zone to a gas-liquid separation tank, circulating the remainer of the hot water in conjunction with the cooling hot water to the cooling zone, supplying the hot water separated in the gas-liquid separation tank to the reaction zone to remove the heat of the oxidation reaction, and circulating the hot water extracted in the form of a gas-liquid mixed phase to the gas-liquid separation tank. The method is excellent to prevent isomerization of ethylene oxide to acetaldelyde which is impurity, excels in thermal efficiency and exhibits ideal durability of the partition plate.

Method for production of ethylene oxide

In the recovery of ethylene oxide from the gas resulting from catalytic gas-phase oxidation of ethylene with a molecular oxygen-containing gas and consequently containing ethylene oxide, a method which comprises subjecting the bottom liquid of an ethylene oxide stripper to a flashing treatment thereby separating the bottom liquid into a vapor-phase part and a liquid-phase part, introducing the vapor-phase part in a compressed state into the bottom of the ethylene oxide stripper, and circulating the liquid-phase part to the absorber. The liquid-phase part, after exchanging heat with the bottom of the ethylene oxide absorber, is caused by a heat pump to liberate thermal energy and generate steam. Further, the liquid-phase part can be used as a heat source for the ethylene oxide refiner and/or the light ends stripper. Moreover, the gas from the top of the ethylene oxide stripper can be used as a heat source for the ethylene oxide refiner.

Method for recovery of ethylene oxide

In the purification of ethylene oxide from an ethylene oxide-containing reaction formation gas produced by catalytic gas-phase oxidation of ethylene with a molecular oxygen containing gas, external thermal energy required for heating an ethylene oxide refiner is economized by a method which utilizes the diffusate obtained from the top of an ethylene oxide stripper as a heat source for the refiner. Further, the bottom liquid of the stripper can be used as a heat source for ethylene oxide refiner and/or a light ends stripper.

Method for purification of ethylene oxide and recovery of heat thereof

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Yokohama, Japan

Yukihiko Kakimoto