TWI565689B - Method for manufacturing dichlorohydrin and method for manufacturing epichlorohydrin - Google Patents

Description

Method for producing dichloropropanol and method for producing epichlorohydrin

The present invention relates to a process for producing dichloropropanol, and more particularly to a process for producing dichloropropanol having a phase separator.

At present, the main preparation method of dichloropropanol is propene high-temperature chlorination, which comprises two steps: chlorinating propylene to allyl chloride at high temperature, and using an excessive amount of industrial water. The allyl chloride is reacted with a chlorinating agent to form dichloropropanol. However, the use of propylene high temperature chlorination produces large amounts of wastewater and other waste materials, thus causing technical and environmental problems.

Therefore, a method of directly reacting glycerol with a chlorinating agent in the case of a catalyst to produce dichloropropanol has been developed, which does not generate a large amount of waste water and waste, and is therefore a relatively economical and environmentally friendly manufacturing method.

However, when dichloropropanol is prepared by this method, an azeotrope of dichloropropanol and water is formed, and if an extractant is added to separate the azeotrope to obtain dichloropropanol, the production will be improved. The cost, and the extractant may also form an azeotrope with the catalyst, causing difficulties in recycling the catalyst.

The present invention provides a method for producing dichloropropanol and a method for producing epichlorohydrin, which have a low manufacturing cost.

The present invention provides a method for producing dichloropropanol comprising the following steps. In at least one of the reactors, glycerin is reacted with an aqueous hydrogen chloride solution in the presence of a catalyst to produce an initial product. The first feed from the initial product is passed to a first distillation column comprising a first decanter to produce a first overhead product and a first bottoms product. Passing the first overhead product into the first phase separator, and directly connecting the first water supply device to the first phase separator, and forming the first aqueous phase product and the first organic phase in the first phase separator product. Wherein the first organic phase product comprises dichloropropanol. And, the first organic phase product is taken out.

According to an embodiment of the present invention, in the above method for producing dichloropropanol, the reactor comprises a continuous reactor or a batch reactor.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the catalyst comprises acetic acid or adipic acid.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the initial product includes dichloropropanol and monochloropropanol.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises refluxing the first aqueous phase product to the first distillation column.

According to an embodiment of the present invention, in the above method for producing dichloropropanol, the first aqueous phase product may include an aqueous hydrogen chloride solution.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the first organic phase product may further comprise monochloropropanol.

According to an embodiment of the present invention, in the above method for producing dichloropropanol, the content of dichlorohydrin in the first overhead product may be greater than the content of dichloropropanol in the first bottom product.

According to an embodiment of the present invention, in the above method for producing dichloropropanol, the first feed may be an initial product.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: introducing the initial product into the second distillation column to produce the second overhead product and the second bottom product, wherein the second The overhead product can be used as the first feed to the first distillation column.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the second bottom product may be further refluxed into the reactor.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: introducing a second feed derived from the first bottom product into the third distillation column to produce a third bottom The product and the third bottoms product, wherein the concentration of the aqueous hydrogen chloride solution in the third bottoms product may be greater than the concentration of the aqueous hydrogen chloride solution of the first bottoms product.

According to an embodiment of the present invention, in the above method for producing dichloropropanol, wherein the second feed may be the first bottom product.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the third bottom product may be further refluxed into the reactor.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: introducing a first bottom product into a fourth distillation column comprising a second phase separator to produce a fourth overhead product And a fourth bottoms product, wherein the fourth bottoms product can serve as a second feed to the third distillation column.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: condensing the fourth overhead product into the second phase separator, and forming the first phase separator in the second phase separator. The dihydrate phase product and the second organic phase product, wherein the second organic phase product may comprise dichloropropanol.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises directly connecting the second water supply device to the second phase separator.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises refluxing the second aqueous phase product to the fourth distillation column.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: introducing a first bottom product into a fifth distillation column comprising a side stream and a third phase separator to produce a fifth column; The top product, the side stream product, and the fifth bottoms product, wherein the concentration of the aqueous hydrogen chloride solution in the fifth bottoms product may be greater than the concentration of the aqueous hydrogen chloride solution of the first bottoms product.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the fifth bottom product may be further refluxed into the reactor.

According to an embodiment of the present invention, in the method for producing the dichloropropanol, the method further comprises: condensing the fifth overhead product into the third phase separator, and forming the first phase in the third phase separator. The aqueous trihydrate product and the third organic phase product, wherein the third organic phase product may comprise dichloropropanol.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the third water supply device may be directly connected to the third phase separator.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises refluxing the third aqueous phase product into the fifth distillation column.

According to an embodiment of the present invention, in the method for producing dichloropropanol, wherein the side stream product comprises water.

The present invention provides a method for producing epichlorohydrin comprising the following steps. Dichloropropanol is obtained by the above-described method for producing dichloropropanol. The dichlorohydrin is reacted with sodium hydroxide to produce epichlorohydrin.

Based on the above, in the method for producing dichloropropanol proposed by the present invention, by extracting the azeotrope by using a phase separator to extract dichloropropanol, it is possible to avoid an additional addition of the extracting agent and to reduce the manufacturing cost. In addition, since the extractant is not required, the problem that the extractant and the catalyst may form an azeotrope and the catalyst is difficult to recycle may be avoided. In addition, the concentration of the aqueous solution of hydrogen chloride in the phase separator can be directly adjusted by the water supply device, and the overhead product of the condensed distillation column is effectively phase-separated to smoothly obtain dichloropropanol. On the other hand, since the method for producing epichlorohydrin proposed in the present invention uses epichlorohydrin produced by the above-described method for producing dichloropropanol, the production cost of epichlorohydrin can be effectively reduced.

The above described features and advantages of the invention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing the manufacture of dichloropropanol in accordance with a first embodiment of the present invention. Fig. 2 is a schematic view showing a manufacturing apparatus of dichloropropanol according to a first embodiment of the present invention.

Referring to FIG. 1 and FIG. 2 simultaneously, the method for producing dichloropropanol of the present embodiment includes the following steps. First, in step S100, in at least one reactor 100, glycerin and an aqueous hydrogen chloride solution are reacted in the presence of a catalyst to produce an initial product. Reactor 100 includes a continuous reactor or a batch reactor. In this embodiment, the description is made by taking one reactor 100 as an example, but the invention is not limited thereto, and those skilled in the art can adjust the number of reactors 100 according to the process design. Glycerin is, for example, a by-product of the production of biodiesel or a chemically synthesized glycerol. The catalyst is, for example, acetic acid or adipic acid. The initial products include dichloropropanol and monochloropropanol, of which dichloropropanol is the main product and monochloropropanol is the intermediate product. The initial product may further comprise an unreacted aqueous solution of hydrogen chloride, glycerin and a catalyst.

Next, step S102 can be selectively performed to cause the initial product to enter the distillation column 102 to produce an overhead product and a bottom product. The initial product can be reacted and separated in distillation column 102. The bottom product of the distillation column 102 mainly includes unreacted glycerin, and may further include a small amount of dichloropropanol, a small amount of monochloropropanol, a small amount of an aqueous hydrogen chloride solution, and a catalyst. The bottoms product of distillation column 102 can be refluxed to reactor 100 for continued recycle to increase reaction conversion. The overhead product of distillation column 102 includes a large amount of dichloropropanol, a large amount of monochloropropanol, a large amount of aqueous hydrogen chloride solution, a catalyst and a small amount of glycerin. The distillation column 102 may have a reboiler for heating the distillation column. The top of distillation column 102 can have a condenser for condensing the overhead product to a liquid state. Additionally, the condensed overhead product may be selectively stored in a reflux drum 103 and the condensed overhead product may be partially returned to the distillation column 102.

Next, step S104 is performed to cause the feed from the initial product to enter the distillation column 104 containing the phase separator 106 to produce an overhead product and a bottom product. The feed from the initial product can be reacted and separated in distillation column 102. In this embodiment, the overhead product of the distillation column 102 is taken as an example of the feed of the distillation column 104. Among them, a large amount of dichlorohydrin in the distillation column 104 forms a lower boiling azeotrope with water, and forms an overhead product of the distillation column 104, thus dichlorohydrin in the overhead product of the distillation column 104. The content may be greater than the amount of dichlorohydrin in the bottom product of distillation column 104. The overhead product of distillation column 104 may further comprise a solution of monochloropropanol and hydrogen chloride. The bottom product of distillation column 104 includes a large amount of aqueous hydrogen chloride solution with a large amount of catalyst, and may further include a small amount of dichloropropanol and a small amount of glycerin.

In other embodiments, step S102 may not be performed. At this point, the feed to distillation column 104 can be the initial product of reactor 100, i.e., the initial product of reactor 100 can be passed directly to distillation column 104.

Then, step S106 is performed, the overhead product of the distillation column 104 is condensed and then enters the phase separator 106, and the water supply device 107 is directly connected to the phase separator 106, and the aqueous phase product and the organic phase are formed in the phase separator 106. product. Wherein the aqueous phase product is in the upper layer and the organic phase product is in the lower layer. The organic phase product of phase separator 106 comprises dichlorohydrin and more preferably monochloropropanol. Since the phase separator 106 can separate the azeotrope in the distillation column 104 and take out the dichloropropanol, no additional extractant is required. In addition, since the extractant is not required, the problem that the extractant and the catalyst may form an azeotrope and the catalyst is difficult to recycle may be avoided. The concentration of the aqueous solution of hydrogen chloride in the phase separator 106 can be directly adjusted by the water supply device 107, and the overhead product of the condensed distillation column 104 is effectively phase-separated. The aqueous phase product of phase separator 106 includes an aqueous hydrogen chloride solution and the aqueous phase product can be refluxed to distillation column 104.

Next, in step S108, the organic phase product in the phase separator 106 is taken out to obtain the main product dichloropropanol.

Next, step S110 may be selectively performed to cause the bottom product of the distillation column 104 to enter the distillation column 108 containing the phase separator 110 to produce an overhead product and a bottom product. The overhead product of distillation column 108 includes dichlorohydrin and, more preferably, an aqueous solution of hydrogen chloride. The bottom product of distillation column 108 includes a large amount of aqueous hydrogen chloride solution with a large amount of catalyst, and may further include a small amount of dichloropropanol and a small amount of glycerin.

Next, step S112 is performed to cause the overhead product of the distillation column 108 to be condensed and then enter the phase separator 110, and the aqueous phase product and the organic phase product are formed in the phase separator 110. Wherein, the organic phase product of the phase separator 110 comprises dichloropropanol. Since the phase separator 110 can separate the azeotrope in the distillation column 108 and take out the dichloropropanol, the dichloropropanol in the feed to the distillation column 108 can be further recovered, so that the recovery rate of the main product can be further improved. In addition, since the extractant is not required, the problem that the extractant and the catalyst may form an azeotrope and the catalyst is difficult to recycle may be avoided. The aqueous phase product of phase separator 110 can be refluxed to distillation column 108. The aqueous phase product of phase separator 110 can include water. In addition, when the aqueous phase product of the phase separator 110 includes an aqueous solution of hydrogen chloride, the water supply device 111 can be directly connected to the phase separator 110 to directly adjust the concentration of the aqueous hydrogen chloride solution in the phase separator 110, and the condensed distillation column The overhead product of 108 is effectively phased.

Next, in step S114, the organic phase product of the phase separator 110 is taken out to obtain the main product dichloropropanol.

Next, step S116 can be selectively performed to cause the bottom product of the distillation column 108 to enter the distillation column 112 as a feed to produce an overhead product and a bottom product. Among them, the overhead product of the distillation column 112 includes a large amount of water, and may further include a small amount of dichloropropanol. The bottom product includes a large amount of aqueous hydrogen chloride solution with a large amount of catalyst, and may further include a small amount of glycerin. Wherein, the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 112 may be greater than the concentration of the aqueous hydrogen chloride solution of the bottom product of the distillation column 104, which may be attributed to the overhead product including a large amount of water in the distillation column 112. The separation is carried out to increase the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 112. The bottoms of distillation column 112 can be refluxed to reactor 100 for recycling. Further, since the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 112 is increased, when the aqueous hydrogen chloride solution is recycled, there is no problem that the concentration of the aqueous hydrogen chloride solution is too low, and the reaction rate is largely lowered. Additionally, the condensed overhead product in distillation column 112 can be selectively stored in reflux tank 113 and the condensed overhead product can be partially refluxed to distillation column 112.

In other embodiments, step S110 to step S114 may not be performed. At this time, the feed of the distillation column 112 may be the bottom product of the distillation column 104, that is, the bottom product of the distillation column 104 may directly enter the distillation column 112.

Based on the above examples, it can be seen that by separating the azeotrope using the phase separator 106 and taking out the dichloropropanol, it is possible to avoid additional addition of the extractant and reduce the manufacturing cost. In addition, since the extractant is not required, the problem that the extractant and the catalyst may form an azeotrope and the catalyst is difficult to recycle may be avoided. In addition, the concentration of the aqueous solution of hydrogen chloride in the phase separator 106 can be directly adjusted by the water supply device 107, and the overhead product of the condensed distillation column 104 can be effectively phase-separated to smoothly obtain the main product dichloropropanol.

Figure 3 is a flow chart showing the manufacture of dichloropropanol in accordance with a second embodiment of the present invention. Figure 4 is a schematic view showing a manufacturing apparatus of dichloropropanol according to a second embodiment of the present invention.

Referring to FIG. 1 to FIG. 4 simultaneously, the second embodiment is the same as step S100 to step S108 of the first embodiment, and therefore will not be described again herein. 3 and FIG. 4, after performing step S108, step S118 may be performed to cause the bottom product of the distillation column 104 to enter the distillation column 114 containing the side stream 116 and the phase separator 118 to produce an overhead product, Side stream product and bottom product. The overhead product of distillation column 114 includes dichlorohydrin and water. The side stream product of distillation column 114 includes a large amount of water and may even include a small amount of dichloropropanol. The bottom product of distillation column 114 includes a large amount of aqueous hydrogen chloride solution with a large amount of catalyst, and may further include a small amount of glycerin. Wherein, the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 114 may be greater than the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 104, which may be attributed to the separation of the side stream product containing a large amount of water in the distillation column 114, The concentration of the aqueous hydrogen chloride solution of the bottom product of the distillation column 114 is increased. The bottoms product of distillation column 114 can be refluxed to reactor 100 for recycling. Further, since the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 114 is increased, when the aqueous hydrogen chloride solution is recycled, there is no problem that the concentration of the aqueous hydrogen chloride solution is too low, and the reaction rate is largely lowered.

Next, step S120 is performed to cause the overhead product of the distillation column 114 to be condensed and then enter the phase separator 118 to form an aqueous phase product and an organic phase product in the phase separator 118. The organic phase product of the phase separator 118 contains dichloropropanol. Since the phase separator 118 can separate the azeotrope in the distillation column 114 and take out the dichloropropanol, the dichloropropanol in the feed of the distillation column 114 can be further recovered, so that the recovery rate of the main product can be further improved. In addition, since the extractant is not required, the problem that the extractant and the catalyst may form an azeotrope and the catalyst is difficult to recycle may be avoided. The aqueous phase product of phase separator 118 can be refluxed to distillation column 114. The aqueous phase product of phase separator 118 can include water. Further, when the aqueous phase product includes an aqueous solution of hydrogen chloride, the water supply unit 117 can be directly connected to the phase separator 118 to directly adjust the concentration of the aqueous hydrogen chloride solution in the phase separator 118, and the overhead product of the condensed distillation column 114. Effective phase separation.

Next, in step S122, the organic phase product of the phase separator 118 is taken out to obtain the main product dichloropropanol.

Based on the above embodiment, since the second embodiment uses the distillation column 114 including the side stream 116 and the phase separator 118 in place of the distillation column 108 and the distillation column 112 in the first embodiment, the number of distillation columns can be reduced.

Further, the method for producing epichlorohydrin according to an embodiment of the present invention includes the following steps. Dichloropropanol was obtained by the method for producing dichloropropanol in the above examples. Next, dichlorohydrin is reacted with sodium hydroxide to produce epichlorohydrin. Since the method for producing epichlorohydrin in the above embodiment uses epichlorohydrin produced by the above-described method for producing dichloropropanol, the production cost of epichlorohydrin can also be effectively reduced.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧reactor
102, 104, 108, 112, 114‧‧‧ distillation tower
103, 113‧‧‧Reflow tank
106, 110, 118‧ ‧ phase splitter
107, 111, 117‧‧‧ water supply device
116‧‧‧ sidestream
S100~S122‧‧‧Steps

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing the manufacture of dichloropropanol in accordance with a first embodiment of the present invention. Fig. 2 is a schematic view showing a manufacturing apparatus of dichloropropanol according to a first embodiment of the present invention. Figure 3 is a flow chart showing the manufacture of dichloropropanol in accordance with a second embodiment of the present invention. Figure 4 is a schematic view showing a manufacturing apparatus of dichloropropanol according to a second embodiment of the present invention.

S100~S116‧‧‧Steps

Claims (25)

A method for producing dichloropropanol, comprising: reacting glycerin with an aqueous hydrogen chloride solution in an atmosphere in which a catalyst is present in at least one reactor to produce an initial product; and causing a first feed derived from the initial product Entering a first distillation column comprising a first phase separator to produce a first overhead product and a first bottoms product; subjecting the first overhead product to condensation to enter the first phase separator, and a water supply device is directly connected to the first phase separator, and a first aqueous phase product and a first organic phase product are formed in the first phase separator, wherein the first organic phase product comprises dichloropropanol And removing the first organic phase product. The method for producing dichloropropanol according to claim 1, wherein the at least one reactor comprises a continuous reactor or a batch reactor. The method for producing dichloropropanol according to claim 1, wherein the catalyst comprises acetic acid or adipic acid. The method for producing dichloropropanol according to claim 1, wherein the initial product comprises dichloropropanol and monochloropropanol. The method for producing dichloropropanol according to claim 1, further comprising refluxing the first aqueous phase product to the first distillation column. The method for producing dichloropropanol according to claim 1, wherein the first aqueous phase product comprises an aqueous hydrogen chloride solution. The method for producing dichloropropanol according to claim 1, wherein the first organic phase product further comprises monochloropropanol. The method for producing dichloropropanol according to claim 1, wherein the content of the dichlorohydrin in the first overhead product is greater than the content of dichloropropanol in the first bottom product. . The method for producing dichloropropanol according to claim 1, wherein the first feed is the initial product. The method for producing dichloropropanol according to claim 1, further comprising: introducing the initial product into a second distillation column to produce a second overhead product and a second bottom product, wherein the second The overhead product serves as the first feed to the first distillation column. The method for producing dichloropropanol according to claim 10, further comprising refluxing the second bottom product into the reactor. The method for producing dichloropropanol according to claim 1, further comprising: introducing a second feed derived from the first bottom product into the third distillation column to produce a third overhead product and a third bottoms product wherein the concentration of the aqueous hydrogen chloride solution in the third bottoms product is greater than the concentration of the aqueous hydrogen chloride solution of the first bottoms product. The method for producing dichloropropanol according to claim 12, wherein the second feed is the first bottom product. The method for producing dichloropropanol according to claim 12, further comprising refluxing the third bottom product into the reactor. The method for producing dichloropropanol according to claim 12, further comprising: introducing the first bottom product into a fourth distillation column comprising a second phase separator to produce a fourth overhead product and A four bottoms product, wherein the fourth bottoms product is the second feed to the third distillation column. The method for producing dichloropropanol according to claim 15, further comprising condensing the fourth overhead product into the second phase separator, and in the second phase separator A second aqueous phase product is formed with the second organic phase product, wherein the second organic phase product comprises dichloropropanol. The method for producing dichloropropanol according to claim 16, further comprising directly connecting the second water supply device to the second phase separator. The method for producing dichloropropanol according to claim 16, further comprising refluxing the second aqueous phase product to the fourth distillation column. The method for producing dichloropropanol according to claim 1, further comprising: introducing the first bottom product into a fifth distillation column comprising a side stream and a third phase separator to produce a fifth column top a product, a side stream product, and a fifth bottoms product, wherein the concentration of the aqueous hydrogen chloride solution in the fifth bottoms product is greater than the concentration of the aqueous hydrogen chloride solution of the first bottoms product. The method for producing dichloropropanol according to claim 19, further comprising refluxing the fifth bottom product into the reactor. The method for producing dichloropropanol according to claim 19, further comprising: condensing the fifth overhead product into the third phase separator, and in the third phase separator A third aqueous phase product is formed with the third organic phase product, wherein the third organic phase product comprises dichloropropanol. The method for producing dichloropropanol according to claim 21, further comprising directly connecting the third water supply device to the third phase separator. The method for producing dichloropropanol according to claim 21, further comprising refluxing the third aqueous phase product into the fifth distillation column. The method for producing dichloropropanol according to claim 19, wherein the side stream product comprises water. A method for producing epichlorohydrin, comprising : obtaining dichloropropanol by a method for producing dichloropropanol according to claim 1; and reacting dichloropropanol with sodium hydroxide; Produces epichlorohydrin.