JP2005097205A - Method for purifying propylene oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent method for purifying propylene oxide by which 3-5C hydrocarbons are efficiently removed from the propylene oxide containing the 3-5C hydrocarbons as impurities. <P>SOLUTION: The method for purifying the propylene oxide by removing the 3-5C hydrocarbons from the propylene oxide containing the 3-5C hydrocarbons as the impurities involves a hydrocarbon-removing step regulated so that the concentration of water is ≥1,000 wt. ppm. The 3-5C hydrocarbons are efficiently removed as a vapor phase fraction by introducing a low-boiling point gas such as nitrogen to the propylene oxide having the regulated water concentration and containing the 3-5C hydrocarbon as the impurities. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for purifying propylene oxide. More specifically, the present invention relates to a purification method having an excellent feature that hydrocarbons having 3 to 5 carbon atoms can be efficiently removed from propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities.

  As a method for producing propylene oxide, a method of reacting an organic peroxide and propylene in the presence of a catalyst is known. In addition to the target propylene oxide, the reaction solution obtained by such a reaction contains oxygen-containing compounds such as water, hydrocarbons, methanol, formaldehyde, acetaldehyde, propionaldehyde, acetone, and methyl formate as impurities. It is common. Therefore, a multistage purification process for separating and recovering high-purity propylene oxide from the reaction solution is required.

  Patent Document 1 discloses a method of removing light boiling components and heavy components by distillation in the purification of propylene oxide. Patent Document 2 discloses a method in which an alkane such as octane effectively removes hydrocarbon impurities having 6 carbon atoms. Further, Patent Document 3 discloses a method in which an alkane such as octane effectively removes hydrocarbon impurities having 6 carbon atoms. Patent Document 4 discloses a method for effectively removing impurities such as methanol, propionaldehyde, and acetone in which hydrocarbons such as octane are contained in propylene oxide.

U.S. Pat. No. 3,881996 U.S. Pat. No. 3,843,488 Japanese Patent Publication No. 50-7571 US Pat. No. 5,133,839

  Under such circumstances, the problem to be solved by the present invention has an excellent feature that hydrocarbons having 3 to 5 carbon atoms can be efficiently removed from propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities. The point is to provide a purification method.

  That is, the present invention relates to a method for removing hydrocarbons having 3 to 5 carbon atoms from a propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as an impurity in the gas phase part. The present invention relates to a method for purifying propylene oxide that is at least ppm.

  According to the present invention, it was possible to provide a purification method having an excellent feature that hydrocarbons having 3 to 5 carbon atoms can be efficiently removed from propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities.

  The crude propylene oxide used for purification in the present invention is produced by a method such as a chlorohydrin method, an organic peroxide method, or a hydrogen peroxide method. For example, in the organic peroxide method, cumene hydroperoxide produced by oxidation of cumene, ethylbenzene hydroperoxide produced by oxidation of ethylbenzene, isobutyl hydroperoxide produced by oxidation of isobutane and the like By reacting propylene, crude propylene oxide containing oxygen-containing compounds and hydrocarbons as impurities can be obtained.

  The hydrocarbon having 3 to 5 carbon atoms contained as an impurity can be removed after being concentrated as a light boiling component of the distillation column, but it inevitably causes the loss of propylene oxide together with the hydrocarbon impurity having 3 to 5 carbon atoms. .

  It is possible to increase the amount of heat in the distillation column to further concentrate the hydrocarbon impurities having 3 to 5 carbon atoms, but this increases the energy consumption required for purification and increases the equipment of the distillation column, resulting in an increase in equipment costs. For this reason, the concentration of hydrocarbon impurities having 3 to 5 carbon atoms is limited in an industrial sense.

  However, it has been found that when a certain amount or more of water is contained in propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities, the separability of hydrocarbons having 3 to 5 carbon atoms is dramatically increased.

  In the present invention, a hydrocarbon having 3 to 5 carbon atoms in propylene oxide is introduced by introducing a light boiling gas such as nitrogen into propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities whose water concentration is adjusted. Can be efficiently removed as a vapor fraction. The water concentration in propylene oxide needs to be 1000 ppm or more, and preferably 10% or more.

  By reusing wastewater generated inside and outside the process, the water concentration can be adjusted without increasing the amount of wastewater.

  On the other hand, propylene oxide purged together with hydrocarbons having 3 to 5 carbon atoms in the gas phase fraction can also be recovered by washing with the extractant. For example, propylene oxide can be selectively recovered by using water having a low affinity for hydrocarbons as an extractant.

Next, an example explains the present invention.
Example 1
The liquid composition after nitrogen was blown into propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities was analyzed. The water concentration was adjusted by adding water. The results are shown in Table 1.

Claims (4)

In the method for removing hydrocarbons having 3 to 5 carbon atoms from the propylene oxide containing hydrocarbons having 3 to 5 carbon atoms as impurities in the gas phase portion, the water concentration in the hydrocarbon removing step is 1000 ppm by weight or more. Purification method. The method of Claim 1 which controls the water concentration of a hydrocarbon removal process using waste water. The method according to claim 1 or 2, further comprising a step of recovering propylene oxide into a extractant from a gas phase fraction containing 3 to 5 carbon atoms and propylene oxide removed as a gas phase from the hydrocarbon removing step. . The method according to one of claims 1 to 3, wherein the extractant is water.