TW201704192A - Method for manufacturing dichlorohydrin and method for manufacturing epichlorohydrin by using glycerol as raw material - Google Patents

Abstract

A method for manufacturing dichlorohydrin including following steps is provided. In at least one reactor, glycerol and hydrogen chloride solution react in an environment having catalyst, and generate an initial product. The initial product served as a first feed is fed into a first distillation column with a first decanter and a first side-draw to generate a first top product, a first side-draw product, and a first bottom product. The first top product is condensed and then sent into the first decanter, then a first aqueous product and a first organic product are formed in the first decanter. The first organic product includes dichlorohydrin. The first organic product is taken out.

Description

Method for producing dichloropropanol and epichlorohydrin from glycerol

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.

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 initial product is passed as a first feed to a first distillation column comprising a first phase separator and a first side stream to produce a first overhead product, a first side stream product and a first bottoms product. The first overhead product is condensed and passed to the first phase separator to form a first aqueous phase product and a first organic phase product in the first phase separator. Wherein the first organic phase product comprises dichloropropanol. The first organic phase product is removed.

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 directly connecting the first water supply device to the first phase separator.

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 method for producing dichloropropanol, the first organic phase product further comprises monochloropropanol.

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

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises refluxing the first bottom product into the reactor.

According to an embodiment of the invention, in the method for producing dichloropropanol, the first side stream product comprises an aqueous hydrogen chloride solution.

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 side stream product into the second distillation column to produce a second overhead product And a second bottoms product wherein the concentration of the aqueous hydrogen chloride solution in the second bottoms product can be greater than the concentration of the aqueous hydrogen chloride solution in the first side stream product.

According to an embodiment of the invention, in the method for producing dichloropropanol, the second feed may be a first side stream product.

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

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

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises: condensing the third overhead product into the second phase separator, and forming a second in the second phase separator. The aqueous phase product is combined with the second organic phase product, wherein the second organic phase product comprises dichlorohydrin.

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 third distillation column.

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

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises refluxing the fourth bottom product into the reactor.

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 third phase separator, and forming a third phase in the third phase separator. The aqueous phase product is combined with a third organic phase product wherein the third organic phase product comprises dichlorohydrin.

According to an embodiment of the present invention, in the method for producing dichloropropanol, the method further comprises directly connecting the third water supply device 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 fourth distillation column.

According to an embodiment of the invention, in the method for producing dichloropropanol, the second 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. Further, the water content in the distillation column can be lowered by the side stream of the distillation column, so that the reaction conversion rate can be improved. 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. Further, the initial product may further include an unreacted aqueous solution of hydrogen chloride, glycerin, and a catalyst.

Next, step S102 is performed to cause the initial product to enter the distillation column 102 containing the phase separator 106 and the side stream 104 as a feed to produce an overhead product, a side stream product, and a bottom product. The initial product can be reacted and separated in distillation column 102. 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. Wherein the large amount of dichlorohydrin in the distillation column 102 forms a lower boiling azeotrope with water, and forms the overhead product of the distillation column 102, thus the dichlorohydrin in the overhead product of the distillation column 102. The amount may be greater than the dichlorohydrin content of the bottom product and may be greater than the dichlorohydrin content of the side stream product. The overhead product of distillation column 102 may further comprise monochloropropanol and water. The bottom product of the distillation column 102 includes a catalyst and unreacted glycerin, and may further include a small amount of dichloropropanol, a small amount of monochloropropanol, and a small amount of an aqueous hydrogen chloride solution. The bottoms product of distillation column 102 can be refluxed to reactor 100 for continued recycle to increase reaction conversion. The side stream product of distillation column 102 includes an aqueous solution of hydrogen chloride, and may further include a small amount of dichloropropanol, a small amount of catalyst, and a small amount of glycerin. Since the aqueous hydrogen chloride solution in the side stream product of the distillation column 102 contains a large amount of water, the water content in the distillation column 102 can be lowered by the side stream 104 of the distillation column 102, so that the reaction conversion rate can be improved.

Then, step S104 is performed to cause the overhead product of the distillation column 102 to be condensed and then enter the phase separator 106 to form an aqueous phase product and an organic phase product in the phase separator 106. The aqueous phase product in phase separator 106 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 102 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 aqueous phase product of phase separator 106 includes water and the aqueous phase product can be refluxed to distillation column 102. In another embodiment, when the aqueous phase product of the phase separator 106 comprises an aqueous solution of hydrogen chloride, the water supply device 108 can be directly connected to the phase separator 106 to directly adjust the concentration of the aqueous hydrogen chloride solution in the phase separator 106. The overhead product of the condensed distillation column 102 is effectively phase separated.

Next, in step S106, the organic phase product in the phase separator 106 is taken out to obtain the main product dichloropropanol.

Next, step S108 can be selectively performed to cause the side stream product of the distillation column 102 to enter the distillation column 110 containing the phase separator 112 to produce an overhead product and a bottom product. The overhead product of distillation column 110 includes dichloropropanol and may even include water. The bottom product of distillation column 110 includes a large amount of aqueous hydrogen chloride solution and a catalyst, and may further include a small amount of dichloropropanol and a small amount of glycerin.

Next, step S110 is performed to cause the overhead product of the distillation column 110 to be condensed and then enter the phase separator 112 to form an aqueous phase product and an organic phase product in the phase separator 112. Wherein, the organic phase product of the phase separator 112 contains dichloropropanol. Since the phase separator 112 can separate the dichlorohydrin from the azeotrope in the distillation column 110, the dichloropropanol in the feed to the distillation column 110 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 112 can be refluxed to distillation column 110. The aqueous phase product of phase separator 112 includes water. In another embodiment, when the aqueous phase product of the phase separator 112 comprises an aqueous solution of hydrogen chloride, the water supply device 114 can be directly connected to the phase separator 112 to directly adjust the concentration of the aqueous hydrogen chloride solution in the phase separator 112. The overhead product of the condensed distillation column 110 is effectively phase-separated.

Next, in step S112, the organic phase product of the phase separator 112 is taken out to obtain the main product dichloropropanol.

Next, step S114 is selectively performed to cause the bottom product of the distillation column 110 to enter the distillation column 116 as a feed to produce an overhead product and a bottom product. Among them, the overhead product of the distillation column 116 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 and a 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 116 may be greater than the concentration of the aqueous hydrogen chloride solution in the side stream product of the distillation column 102, which may be attributed to the overhead product comprising a large amount of water in the distillation column 116. The separation is carried out to increase the concentration of the aqueous hydrogen chloride solution in the bottom product of the distillation column 116. The bottoms product of distillation column 116 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 116 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 116 can be selectively stored in a reflux drum 118 and the condensed overhead product can be partially returned to distillation column 116.

In other embodiments, step S108 to step S112 may not be performed. At this point, the feed to distillation column 116 can be a side stream product of distillation column 102, i.e., the side stream product of distillation column 102 can be passed directly to distillation column 116.

Based on the above examples, it can be seen that by separating the azeotrope using the phase separator 108 and taking out the dichloropropanol, it is possible to avoid additional addition of the extractant 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. Further, the water content in the distillation column 102 can be lowered by the side stream 104 of the distillation column 102, so that the reaction conversion rate can be improved.

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 S106 of the first embodiment, and therefore will not be described again herein. After performing step S106 in the second embodiment of FIG. 3 and FIG. 4, step S116 may be performed to cause the side stream product of the distillation column 102 to enter the distillation column 120 containing the side stream 122 and the phase separator 124 to produce an overhead product, Side stream product and bottom product. The overhead product of distillation column 120 includes dichloropropanol and may even include water. The side stream product of distillation column 120 includes a large amount of water, and may further include a small amount of dichloropropanol. The bottom product of the distillation column 120 includes a large amount of aqueous hydrogen chloride solution and a 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 120 may be greater than the concentration of the aqueous hydrogen chloride solution in the side stream product of the distillation column 102, which may be attributed to the separation of the side stream product containing a large amount of water in the distillation column 120. The concentration of the aqueous solution of hydrogen chloride in the bottom product of the distillation column 102 is increased. The bottoms of distillation column 120 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 120 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 S118 is performed to cause the overhead product of the distillation column 120 to be condensed and then enter the phase separator 124 to form an aqueous phase product and an organic phase product in the phase separator 124. The organic phase product of the phase separator 124 contains dichloropropanol. Since the phase separator 124 can separate the dichlorohydrin from the azeotrope in the distillation column 120, the dichloropropanol in the feed to the distillation column 120 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 124 can be refluxed to distillation column 120. The aqueous phase product of phase separator 124 can include water. In another embodiment, when the aqueous phase product comprises an aqueous solution of hydrogen chloride, the water supply unit 126 can be directly connected to the phase separator 124 to directly adjust the concentration of the aqueous hydrogen chloride solution in the phase separator 124, and the condensed distillation column The overhead product of 120 is effectively phased.

Next, in step S120, the organic phase product of the phase separator 124 is taken out to obtain the main product dichloropropanol.

Based on the above embodiment, since the second embodiment uses the distillation column 120 including the side stream 122 and the phase separator 124 in place of the distillation column 110 and the distillation column 116 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, 110, 116, 120‧‧‧ distillation tower
118‧‧‧Reflux tank
106, 112, 124‧‧ ‧ phase splitter
108, 114, 126‧‧‧ water supply devices
104, 122‧‧‧ sidestream
S100~S120‧‧‧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~S114‧‧‧Steps

Claims (24)

A method for producing dichloropropanol, comprising: reacting glycerin with an aqueous solution of hydrogen chloride in an atmosphere in which a catalyst is present in at least one reactor to produce an initial product; and using the initial product as a first feed to enter a first a phase separator and a first side stream of the first distillation column to produce a first overhead product, a first side stream product and a first bottoms product; and the first overhead product is condensed to enter the first a phase separator, wherein 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 the first organic phase is taken out 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 directly connecting the first water supply device to the first phase separator. 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 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 side stream product. And greater than the content of dichloropropanol in the first bottom product. The method for producing dichloropropanol according to claim 1, further comprising refluxing the first bottom product into the reactor. The method for producing dichloropropanol according to claim 1, wherein the first side stream product comprises an aqueous hydrogen chloride solution. The method for producing dichloropropanol according to claim 1, further comprising: introducing a second feed derived from the first side stream product into the second distillation column to produce a second overhead product and a second bottoms product wherein the concentration of the aqueous hydrogen chloride solution in the second bottoms product is greater than the concentration of the aqueous hydrogen chloride solution in the first side stream product. The method for producing dichloropropanol according to claim 11, wherein the second feed is the first side stream product. The method for producing dichloropropanol according to claim 11, further comprising refluxing the second bottom product into the reactor. The method for producing dichloropropanol according to claim 11, further comprising: introducing the first side stream product into a third distillation column comprising a second phase separator to produce a third overhead product and A three bottoms product, wherein the third bottoms product is the second feed to the second distillation column. The method for producing dichloropropanol according to claim 14, further comprising: condensing the third 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 15, further comprising directly connecting the second water supply device to the second phase separator. The method for producing dichloropropanol according to claim 15, further comprising refluxing the second aqueous phase product to the third distillation column. The method for producing dichloropropanol according to claim 1, further comprising: introducing the first side stream product into a fourth distillation column comprising a second side stream and a third phase separator to produce a fourth The overhead product, the second side stream product, and the fourth bottoms product, wherein the concentration of the aqueous hydrogen chloride solution in the fourth bottoms product is greater than the concentration of the aqueous hydrogen chloride solution in the first side stream product. The method for producing dichloropropanol according to claim 18, further comprising refluxing the fourth bottom product into the reactor. The method for producing dichloropropanol according to claim 18, further comprising condensing the fourth 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 20, further comprising directly connecting the third water supply device to the third phase separator. The method for producing dichloropropanol according to claim 20, further comprising refluxing the third aqueous phase product into the fourth distillation column. The method for producing dichloropropanol according to claim 18, wherein the second 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.