A method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction

Abstract

This invention provides a method for improving the utilization rate of hydrogen chloride in the chlorination reaction of glycerol, comprising the following steps: (1) passing the chlorinated distillate, the reactive distillation kettle liquid, and the light component and a portion of the heavy component material from the separation unit into a prechlorination reaction unit for prechlorination reaction to obtain gaseous material and prechlorinated reaction liquid; (2) passing glycerol containing a catalyst and the gaseous material into a reactive distillation unit for mixing reaction to obtain aqueous material and reactive distillation kettle liquid; (3) passing hydrogen chloride and the prechlorinated reaction liquid into a chlorination reaction unit for chlorination reaction to obtain chlorinated distillate and chlorinated liquid from the bottom of the tower; (4) passing the chlorinated liquid from the bottom of the tower into a separation unit to obtain dichloropropanol, light component, and heavy component material. The method provided by this invention efficiently utilizes the hydrogen chloride in the chlorinated gaseous material, improves the utilization rate of hydrogen chloride in the chlorination reaction of glycerol, and reduces alkali consumption and energy consumption, thereby achieving stable and clean production of epichlorohydrin using the glycerol method.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology and relates to a method for the efficient utilization of inorganic raw materials in the production of epichlorohydrin using the glycerol method, and particularly to a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction. Background Technology

[0002] Epichlorohydrin (ECH) is an important fine chemical product with a wide range of applications. It is primarily used in the synthesis of epoxy resins, found in adhesives, coatings, casting materials, and reinforcing materials. It also serves as a raw material for various products, including electrical insulation materials, surfactants, ion exchange resins, plasticizers, and chlorohydrin rubbers. With the increased availability of inexpensive glycerol and the numerous advantages of the glycerol process itself, it has become the mainstream method for producing epichlorohydrin both domestically and internationally.

[0003] The chlorination of glycerol involves two steps. First, pre-chlorination produces 3-chloro-1,2-propanediol and water, along with a small amount of 2-chloro-1,3-propanediol. The intermediate is then further chlorinated to yield dichloropropanol (a mixture of 1,3-dichloropropanol and 2,3-dichloropropanol). In actual production, to promote the forward reaction, both chlorination steps produce a light, aqueous component. Both outputs are pseudo-ternary azeotropes of dichloropropanol, hydrogen chloride, and water. The first chlorination step primarily produces 3-chloro-1,2-propanediol, resulting in a low dichloropropanol content (10%-15%), hydrogen chloride content (1%-3%), and water content (80%-88%). This component is difficult to separate efficiently using conventional methods such as distillation, rectification, or analysis, making it difficult to utilize the effective components like hydrogen chloride. Currently, the conventional processing technology for this material is to react it with alkali to produce epichlorohydrin, but the presence of acid in the material will significantly increase the alkali consumption and energy consumption of the process.

[0004] Therefore, how to efficiently utilize hydrogen chloride in the gas phase of chlorination, improve the utilization rate of hydrogen chloride in the glycerol chlorination reaction, and at the same time reduce alkali consumption and energy consumption to achieve stable and clean production of epichlorohydrin via the glycerol process has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the utilization rate of hydrogen chloride in the chlorination reaction of glycerol. The method makes efficient use of hydrogen chloride in the chlorination gas phase product, while reducing alkali consumption and energy consumption, and realizes stable and clean production of epichlorohydrin by glycerol process, which is conducive to large-scale promotion and application.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a method for improving the utilization rate of hydrogen chloride in the chlorination reaction of glycerol, the method comprising the following steps:

[0008] (1) The chlorinated distillate, the reactive distillate, and the light components collected from the separation unit, along with some of the heavy components, are fed into the prechlorination reaction unit to carry out the prechlorination reaction, thereby obtaining gaseous materials and prechlorination reaction liquid.

[0009] (2) The glycerol containing the catalyst and the gaseous material obtained in step (1) are fed into the reactive distillation unit for mixing and reaction to obtain the aqueous material and the reactive distillation kettle liquid, which is recycled for step (1).

[0010] (3) Pass hydrogen chloride and the prechlorination reaction solution obtained in step (1) into the chlorination reaction unit to carry out the chlorination reaction, and obtain chlorinated distillate and chlorinated liquid in the bottom of the tower. The chlorinated distillate is recycled for step (1).

[0011] (4) The chlorinated liquid obtained in step (3) is passed into the separation unit to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1).

[0012] The method provided by this invention reacts the gaseous material collected from the prechlorination reaction unit with glycerol containing a catalyst, fully recovers and utilizes the hydrogen chloride in the gaseous material, further improves the utilization rate of hydrogen chloride in the glycerol chlorination reaction, successfully destroys the pseudo ternary azeotropic system of the gaseous material, and enables the efficient separation of each component after the reaction.

[0013] Furthermore, the gaseous material from the prechlorination reaction unit enters the reactive distillation unit, where the gaseous contact with the substrate further enhances the reaction efficiency. At the same time, the heat of vaporization of the prechlorinated gaseous material is fully utilized, significantly reducing the energy consumption of the reactive distillation unit.

[0014] Furthermore, this invention processes the originally difficult-to-handle pseudo-ternary azeotropic material into an aqueous phase material and chlorination raw material. The aqueous phase material can be directly subjected to alkaline hydrolysis and biochemical treatment, thereby further reducing the alkali consumption and energy consumption of subsequent saponification, and realizing the stable and clean production of epichlorohydrin by the glycerol method.

[0015] Preferably, the prechlorination reaction unit in step (1) includes a three-stage prechlorination reactor, and the residence time of the reactants in each stage of the prechlorination reactor is independently 1-6h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, more preferably 2-4h, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0016] Preferably, the chlorinated distillate in step (1) comprises the following components by mass percentage:

[0017]

[0018] The monochloropropanediol has a mass percentage of 0-0.1%, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%; the dichloropropane has a mass percentage of 30%-40%, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; and the hydrogen chloride has a mass percentage of 20%-30%, for example, 20%, 21%, 22%, 23%, 24%, or 2%. The percentages of glycerol by mass are 5%, 26%, 27%, 28%, 29%, or 30%, and the percentage of glycerol by mass is 0-0.1%, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. The percentage of water by mass is 30%-40%, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0019] Preferably, the reactive distillation vessel liquid in step (1) comprises the following components by mass percentage:

[0020]

[0021] The monochloropropanediol has a mass percentage of 10%-15%, for example, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%; the dichloropropane has a mass percentage of 0-1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%; and the glycerol has a mass percentage of... The percentage is 80%-85%, for example, it can be 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5% or 85%, and the mass percentage of water is 0-5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, but is not limited to the listed values, and other unlisted values ​​within this range also apply.

[0022] Preferably, the light component in step (1) comprises the following components by mass percentage:

[0023] Dichloropropanol 20%-30%;

[0024] Hydrogen chloride 10%-18%;

[0025] Water content: 55%-65%.

[0026] The mass percentage of dichloropropanol is 0-1%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%; the mass percentage of hydrogen chloride is 10%-18%, for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, or 18%; and the mass percentage of water is 55%-65%, for example, it can be 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, or 65%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the recombinant material in step (1) comprises the following components by mass percentage:

[0028]

[0029] The remainder consists of catalysts and catalyst derivatives.

[0030] The monochloropropanediol has a mass percentage of 10%-25%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25%; the dichloropropane has a mass percentage of 0-10%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%; and the hydrogen chloride has a mass percentage of 0-0.5%, for example, it can be 0.05%, 0.1%, or 0.5%. The percentages of glycerol by mass are 0.05%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, and the percentage of water by mass is 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, but are not limited to the listed values; other unlisted values ​​within this range also apply.

[0031] Preferably, the gaseous material in step (1) comprises the following components by mass percentage:

[0032] Dichloropropanol 10%-15%;

[0033] Hydrogen chloride 1%-3%;

[0034] Water content: 80%-88%.

[0035] The dichloropropanol has a mass percentage of 10%-15%, for example, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%, and the hydrogen chloride has a mass percentage of 1%-3%, for example, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, etc. 2.8% or 3%, wherein the water mass percentage is 80%-88%, for example, it can be 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, 85%, 85.5%, 86%, 86.5%, 87%, 87.5% or 88%, but is not limited to the listed values, and other unlisted values ​​within this range also apply.

[0036] Preferably, the mass of the gaseous material in step (1) accounts for 18%-22% of the total mass of the feed to the prechlorination reaction unit. For example, it can be 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5% or 22%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the gaseous material in step (2) passes through a steady-state buffer feeder and a gas distributor in sequence before being fed into the reactive distillation unit.

[0038] Preferably, the glycerol in step (2) is preheated and then mixed with the catalyst before feeding, and the preheating temperature is ≥80℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃ or 100℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the catalyst in step (2) comprises a dicarboxylic acid catalyst with a boiling point ≥150°C, for example, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] Preferably, the mass of the catalyst in step (2) is 0.5%-10% of the mass of glycerol, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, more preferably 2%-8%, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] Preferably, the mass ratio of the catalyst-containing glycerol to the reactive distillation vessel liquid in step (2) is 1:(1.1-1.2), for example, it can be 1:1.1, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19 or 1:1.2, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the mass ratio of the glycerol containing the catalyst in step (2) to the chlorinated distillate in step (3) is 1:(0.5-0.6), for example, it can be 1:0.5, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, 1:0.56, 1:0.57, 1:0.58, 1:0.59 or 1:0.6, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the mass ratio of the glycerol containing the catalyst in step (2) to the light component in step (4) is 1:(0.08-0.12), for example, it can be 1:0.08, 1:0.085, 1:0.09, 1:0.095, 1:0.1, 1:0.105, 1:0.11, 1:0.115 or 1:0.12, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the mass ratio of the glycerol containing the catalyst in step (2) to the heavy component material in step (4) is 1:(0.5-0.6), for example, it can be 1:0.5, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, 1:0.56, 1:0.57, 1:0.58, 1:0.59 or 1:0.6, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the reactive distillation unit in step (2) includes a reactive distillation column.

[0046] Preferably, the bottom temperature of the reactive distillation column is 60-130°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C or 130°C, more preferably 120-130°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] Preferably, the top temperature of the reactive distillation column is 50-100°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, more preferably 55-75°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0048] Preferably, the pressure inside the reactive distillation column is between -85 kPa and -30 kPa, for example, it can be -85 kPa, -80 kPa, -75 kPa, -70 kPa, -65 kPa, -60 kPa, -55 kPa, -50 kPa, -45 kPa, -40 kPa, -35 kPa or -30 kPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] Preferably, the residence time of the material in the reactive distillation column is 0.5-2h, for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the number of trays in the reactive distillation column is 20-45, for example, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 or 45, more preferably 25-35, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] Preferably, the reflux ratio of the reactive distillation column is 0.5-3, for example, it can be 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, more preferably 1.5-2.5, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0052] Preferably, the aqueous phase material in step (2) comprises the following components by mass percentage:

[0053] Dichloropropanol 0-0.2%;

[0054] Hydrogen chloride 0-0.3%;

[0055] Water content: 99.5%-100%.

[0056] The mass percentage of dichloropropanol is 0-0.2%, for example, it can be 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, or 0.2%; the mass percentage of hydrogen chloride is 0-0.3%, for example, it can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%; and the mass percentage of water is 99.5%-100%, for example, it can be 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the mass ratio of the aqueous phase material to the reactive distillation vessel liquid in step (2) is 1:(3-5), for example, it can be 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] Preferably, the chlorination reaction unit in step (3) includes at least two chlorination reactors, and hydrogen chloride and prechlorination reaction liquid are introduced into the first chlorination reactor and overflow into the next chlorination reactor, and gas phase extraction begins in the second chlorination reactor. The chlorinated distillate from each chlorination reactor is combined and reused in step (1).

[0059] Preferably, the mass percentage of the recombinant material in step (4) recycled to step (1) is ≥20%, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] It should be noted that the above "%" refers to mass percentage; "monochloropropanediol" refers to 3-chloro-1,2-propanediol and / or 2-chloro-1,3-propanediol; "dichloropropanol" refers to 1,3-dichloropropanol and / or 2,3-dichloropropanol; the step of chlorination of glycerol to monochloropropanediol in the first step is referred to as "pre-chlorination", and the step of chlorination of glycerol to dichloropropanol in the second step is referred to as "chlorination".

[0061] In this invention, the chemical reaction that occurs during the prechlorination is as follows:

[0062]

[0063] The chemical reaction that occurs during chlorination is as follows:

[0064]

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] (1) The method provided by the present invention reacts the gaseous material collected from the prechlorination reaction unit with glycerol containing a catalyst, fully recovers and utilizes the hydrogen chloride in the gaseous material, further improves the utilization rate of hydrogen chloride in the glycerol chlorination reaction, successfully destroys the pseudo ternary azeotropic system of the gaseous material, and enables the components to be separated efficiently after the reaction.

[0067] (2) The gaseous material collected from the prechlorination reaction unit enters the reactive distillation unit. The gaseous contact with the substrate will further enhance the reaction effect. At the same time, the heat of vaporization of the prechlorination gaseous material is fully utilized, which significantly reduces the energy consumption of the reactive distillation unit.

[0068] (3) The present invention processes the originally difficult-to-handle pseudo-ternary azeotropic material into an aqueous phase material and chlorination raw material. The aqueous phase material can be directly treated by alkaline hydrolysis and biochemical treatment, thereby further reducing the alkali consumption and energy consumption of subsequent saponification, and realizing the stable and clean production of epichlorohydrin by glycerol method. Attached Figure Description

[0069] Figure 1 This is a flowchart of the method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction provided by the present invention. Detailed Implementation

[0070] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0071] This invention provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, such as... Figure 1 As shown, the method includes the following steps:

[0072] (1) The chlorinated distillate, the reactive distillate, and the light components collected from the separation unit, along with some of the heavy components, are fed into the prechlorination reaction unit for prechlorination reaction to obtain gaseous materials and prechlorinated reaction liquid; the prechlorination reaction unit includes three-stage prechlorination reactors, and the residence time of the reactants in each stage of the prechlorination reactor is independently 2-4 hours.

[0073] The chlorinated distillate comprises the following components by mass percentage:

[0074]

[0075] The reactive distillation vessel liquid comprises the following components by mass percentage:

[0076]

[0077] The light component comprises the following components by mass percentage:

[0078] Dichloropropanol 20%-30%;

[0079] Hydrogen chloride 10%-18%;

[0080] Water 55%-65%;

[0081] The heavy component material comprises the following components by mass percentage:

[0082]

[0083]

[0084] The remainder consists of catalysts and catalyst derivatives;

[0085] The gaseous material comprises the following components by mass percentage:

[0086] Dichloropropanol 10%-15%;

[0087] Hydrogen chloride 1%-3%;

[0088] Water content 80%-88%;

[0089] The mass of the gaseous material accounts for 18%-22% of the total mass of the feed to the prechlorination reaction unit.

[0090] (2) The glycerol containing the catalyst and the gaseous material obtained in step (1) are fed into the reactive distillation unit for mixing and reaction. Before being fed into the reactive distillation unit, the gaseous material is passed through a steady-state buffer feeder and a gas distributor to obtain an aqueous material and a reactive distillation kettle liquid. The reactive distillation kettle liquid is recycled for step (1). The glycerol is preheated and then mixed with a dicarboxylic acid catalyst with a boiling point ≥150℃ and fed at a preheating temperature ≥80℃. The mass of the dicarboxylic acid catalyst accounts for 2%-8% of the mass of the glycerol.

[0091] The reactive distillation unit includes a reactive distillation column, wherein the bottom temperature of the reactive distillation column is 120-130℃, the top temperature is 55-75℃, the internal pressure is -85kPa to -30kPa, the material residence time is 0.5-2h, the number of trays is 25-35, and the reflux ratio is 1.5-2.5.

[0092] The aqueous phase material comprises the following components by mass percentage:

[0093] Dichloropropanol 0-0.2%;

[0094] Hydrogen chloride 0-0.3%;

[0095] Water content 99.5%-100%;

[0096] The mass ratio of the aqueous phase material to the reactive distillation vessel liquid is 1:(3-5).

[0097] (3) Pass hydrogen chloride and the prechlorination reaction solution obtained in step (1) into the chlorination reaction unit to carry out the chlorination reaction, and obtain chlorinated distillate and chlorinated liquid in the bottom of the tower. The chlorinated distillate is recycled for step (1).

[0098] The chlorination reaction unit includes at least two chlorination reactors, and hydrogen chloride and prechlorination reaction liquid are fed into the first chlorination reactor and overflowed into the next chlorination reactor. The gas phase is extracted in the second chlorination reactor. The chlorinated distillate from each chlorination reactor is combined and reused in step (1).

[0099] (4) The chlorinated liquid obtained in step (3) is passed into the separation unit to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is ≥20%.

[0100] In this invention, the mass ratio of the glycerol containing the catalyst in step (2) to the reactive distillation vessel liquid is 1:(1.1-1.2), the mass ratio of the chlorinated distillate in step (3) is 1:(0.5-0.6), the mass ratio of the light component in step (4) is 1:(0.08-0.12), and the mass ratio of the heavy component in step (4) is 1:(0.5-0.6).

[0101] Example 1

[0102] This embodiment provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, the method comprising the following steps:

[0103] (1) The chlorinated distillate, the reactive distillation kettle liquid, and the light components and some heavy components collected from the separation unit are fed into the prechlorination reaction tower at a mass ratio of 1:1.9:1:0.2 for prechlorination reaction. The temperature of the first-stage prechlorination reaction is controlled at 125℃ and the pressure at 0.1MPa; the temperature of the second-stage prechlorination reaction is controlled at 110℃ and the pressure at -45kPa; and the temperature of the third-stage prechlorination reaction is controlled at 90℃ and the pressure at -70kPa. The residence time of the materials in each stage of the prechlorination reaction is 2h. The gaseous material collected from the top of each stage of the prechlorination tower enters the steady-state buffer feeder and then enters the reactive distillation tower.

[0104] (2) The reactive distillation feed contains glycerol with 6 wt% dicarboxylic acid catalyst and the gaseous material from the top of the prechlorination tower, with a feed weight ratio of 2.4:1. The gaseous material from the top of the prechlorination tower contains 14.56% dichloropropanol, 1.86% hydrogen chloride, and 83.58% water by mass percentage, and enters the reactive distillation tower from the gaseous tower. The bottom temperature of the reactive distillation tower is 129.3℃, the top temperature is 71℃, and the internal pressure is -33kPa.

[0105] Based on mass percentage, the composition of the top product of the reactive distillation column is 0.06% dichloropropanol, 0.11% hydrogen chloride, and 99.83% water; the composition of the bottom product is 11.52% monochloropropanediol, 0.077% dichloropropanol, 82.13% glycerol, and 4.36% water.

[0106] (3) Pass hydrogen chloride and the prechlorination reaction liquid obtained in step (1) into the first-stage chlorination reactor, and enter the next-stage chlorination reactor by overflow. In the second-stage chlorination reactor, the gas phase is extracted. The chlorinated distillate from each stage of the chlorination reactor is combined and reused in step (1).

[0107] (4) The chlorinated liquid obtained in step (3) is passed into a separator to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is 60%.

[0108] Example 2

[0109] This embodiment provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, the method comprising the following steps:

[0110] (1) The chlorinated distillate, the reactive distillation kettle liquid, and the light components and some heavy components collected from the separation unit are fed into the prechlorination reaction tower at a mass ratio of 1:2.0:1:0.2 for prechlorination reaction. The temperature of the first-stage prechlorination reaction is controlled at 120℃ and the pressure at 0.1MPa; the temperature of the second-stage prechlorination reaction is controlled at 110℃ and the pressure at -45kPa; and the temperature of the third-stage prechlorination reaction is controlled at 90℃ and the pressure at -70kPa. The residence time of the materials in each stage of the prechlorination reaction is 2.5h. The gaseous material collected from the top of each stage of the prechlorination tower enters the steady-state buffer feeder before being fed into the reactive distillation tower.

[0111] (2) The reactive distillation feed contains glycerol with 8 wt% dicarboxylic acid catalyst and the gaseous material from the top of the prechlorination tower, with a feed weight ratio of 2.5:1. The gaseous material from the top of the prechlorination tower contains 12.84% dichloropropanol, 1.28% hydrogen chloride, and 87.16% water by mass percentage. It enters the reactive distillation tower from the gaseous tower. The bottom temperature of the reactive distillation tower is 124.5℃, the top temperature is 66℃, and the internal pressure is -38kPa.

[0112] Based on mass percentage, the composition of the top product of the reactive distillation column is 0.07% dichloropropanol, 0.14% hydrogen chloride, and 99.79% water; the composition of the bottom product is 12.39% monochloropropanediol, 0.068% dichloropropanol, 81.07% glycerol, and 4.49% water.

[0113] (3) Pass hydrogen chloride and the prechlorination reaction liquid obtained in step (1) into the first-stage chlorination reactor, and enter the next-stage chlorination reactor by overflow. In the second-stage chlorination reactor, the gas phase is extracted. The chlorinated distillate from each stage of the chlorination reactor is combined and reused in step (1).

[0114] (4) The chlorinated liquid obtained in step (3) is passed into a separator to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is 60%.

[0115] Example 3

[0116] This embodiment provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, the method comprising the following steps:

[0117] (1) The chlorinated distillate, the reactive distillation kettle liquid, and the light components and some heavy components collected from the separation unit are fed into the prechlorination reaction tower at a mass ratio of 1:1.8:1:0.16 for prechlorination reaction. The temperature of the first-stage prechlorination reaction is controlled at 125℃ and the pressure at 0.1MPa; the temperature of the second-stage prechlorination reaction is controlled at 120℃ and the pressure at 0.1MPa; and the temperature of the third-stage prechlorination reaction is controlled at 90℃ and the pressure at -70kPa. The residence time of the materials in each stage of the prechlorination reaction is 3h. The gaseous material collected from the top of each stage of the prechlorination tower enters the steady-state buffer feeder and then enters the reactive distillation tower.

[0118] (2) The reactive distillation feed contains glycerol with 4.5 wt% dicarboxylic acid catalyst and the gaseous material from the top of the prechlorination tower, with a feed weight ratio of 2.4:1. The gaseous material from the top of the prechlorination tower contains 14.72% dichloropropanol, 2.61% hydrogen chloride, and 82.67% water by mass percentage, and enters the reactive distillation tower from the gaseous tower. The bottom temperature of the reactive distillation tower is 122.2℃, the top temperature is 63℃, and the internal pressure is -42kPa.

[0119] Based on mass percentages, the composition of the top product of the reactive distillation column is 0.09% dichloropropanol, 0.13% hydrogen chloride, and 99.78% water; the composition of the bottom product is 13.11% monochloropropanediol, 0.062% dichloropropanol, 83.92% glycerol, and 3.88% water.

[0120] (3) Pass hydrogen chloride and the prechlorination reaction liquid obtained in step (1) into the first-stage chlorination reactor, and enter the next-stage chlorination reactor by overflow. In the second-stage chlorination reactor, the gas phase is extracted. The chlorinated distillate from each stage of the chlorination reactor is combined and reused in step (1).

[0121] (4) The chlorinated liquid obtained in step (3) is passed into a separator to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is 50%.

[0122] Example 4

[0123] This embodiment provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, the method comprising the following steps:

[0124] (1) The chlorinated distillate, the reactive distillation kettle liquid, and the light components and some heavy components collected from the separation unit are fed into the prechlorination reaction tower at a mass ratio of 1:1.9:0.95:0.18 for prechlorination reaction. The temperature of the first-stage prechlorination reaction is controlled at 115℃ and the pressure at 0.1MPa; the temperature of the second-stage prechlorination reaction is controlled at 115℃ and the pressure at 0.1MPa; and the temperature of the third-stage prechlorination reaction is controlled at 95℃ and the pressure at -62kPa. The residence time of the materials in each stage of the prechlorination reaction is 2h. The gaseous materials collected from the top of each stage of the prechlorination tower are fed into the steady-state buffer feeder before being fed into the reactive distillation tower.

[0125] (2) The reactive distillation feed contains glycerol with 7 wt% dicarboxylic acid catalyst and the gaseous material from the top of the prechlorination tower, with a feed weight ratio of 2.4:1. The gaseous material from the top of the prechlorination tower contains 14.84% dichloropropanol, 2.87% hydrogen chloride, and 82.29% water by mass percentage. It enters the reactive distillation tower from the gaseous tower. The bottom temperature of the reactive distillation tower is 128.2℃, the top temperature is 70℃, and the internal pressure is -34kPa.

[0126] By mass percentage, the composition of the top product of the reactive distillation column is 0.11% dichloropropanol, 0.16% hydrogen chloride, and 99.73% water; the composition of the bottom product is 11.03% monochloropropanediol, 0.058% dichloropropanol, 84.09% glycerol, and 4.56% water.

[0127] (3) Pass hydrogen chloride and the prechlorination reaction liquid obtained in step (1) into the first-stage chlorination reactor, and enter the next-stage chlorination reactor by overflow. In the second-stage chlorination reactor, the gas phase is extracted. The chlorinated distillate from each stage of the chlorination reactor is combined and reused in step (1).

[0128] (4) The chlorinated liquid obtained in step (3) is passed into a separator to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is 60%.

[0129] Example 5

[0130] This embodiment provides a method for improving the utilization rate of hydrogen chloride in the glycerol chlorination reaction, the method comprising the following steps:

[0131] (1) The chlorinated distillate, the reactive distillation kettle liquid, and the light components and some heavy components collected from the separation unit are fed into the prechlorination reaction tower at a mass ratio of 1:2:0.95:0.18 for prechlorination reaction. The temperature of the first-stage prechlorination reaction is controlled at 122℃ and the pressure at 0.1MPa; the temperature of the second-stage prechlorination reaction is controlled at 110℃ and the pressure at -45kPa; and the temperature of the third-stage prechlorination reaction is controlled at 100℃ and the pressure at -50kPa. The residence time of the materials in each stage of the prechlorination reaction is 2h. The gaseous material collected from the top of each stage of the prechlorination tower enters the steady-state buffer feeder and then enters the reactive distillation tower.

[0132] (2) The reactive distillation feed contains glycerol with 6 wt% dicarboxylic acid catalyst and the gaseous material from the top of the prechlorination tower, with a feed weight ratio of 2.45:1. The gaseous material from the top of the prechlorination tower contains 13.46% dichloropropanol, 2.26% hydrogen chloride, and 84.28% water by mass percentage. It enters the reactive distillation tower from the gaseous tower. The bottom temperature of the reactive distillation tower is 125.2℃, the top temperature is 66℃, and the internal pressure is -37kPa.

[0133] By mass percentage, the composition of the top product of the reactive distillation column is 0.05% dichloropropanol, 0.08% hydrogen chloride, and 99.87% water; the composition of the bottom product is 12.91% monochloropropanediol, 0.056% dichloropropanol, 82.87% glycerol, and 4.16% water.

[0134] (3) Pass hydrogen chloride and the prechlorination reaction liquid obtained in step (1) into the first-stage chlorination reactor, and enter the next-stage chlorination reactor by overflow. In the second-stage chlorination reactor, the gas phase is extracted. The chlorinated distillate from each stage of the chlorination reactor is combined and reused in step (1).

[0135] (4) The chlorinated liquid obtained in step (3) is passed into a separator to obtain dichloropropanol, light components and heavy components. The dichloropropanol is prepared into epichlorohydrin by saponification. The light components and some heavy components are recycled in step (1), and the mass percentage of the heavy components recycled in step (1) is 60%.

[0136] The method provided by this invention reacts the gaseous material collected from the prechlorination reaction unit with glycerol containing a catalyst, fully recovers and utilizes the hydrogen chloride in the gaseous material, further improves the utilization rate of hydrogen chloride in the glycerol chlorination reaction, successfully destroys the pseudo ternary azeotropic system of the gaseous material, and enables the efficient separation of each component after the reaction.

[0137] Furthermore, the gaseous material from the prechlorination reaction unit enters the reactive distillation unit, where the gaseous contact with the substrate further enhances the reaction efficiency. At the same time, the heat of vaporization of the prechlorinated gaseous material is fully utilized, significantly reducing the energy consumption of the reactive distillation unit.

[0138] Furthermore, this invention processes the originally difficult-to-handle pseudo-ternary azeotropic material into an aqueous phase material and chlorination raw material. The aqueous phase material can be directly subjected to alkaline hydrolysis and biochemical treatment, thereby further reducing the alkali consumption and energy consumption of subsequent saponification, and realizing the stable and clean production of epichlorohydrin by the glycerol method.

[0139] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for improving the utilization of hydrogen chloride in the chlorination of glycerol, characterized in that, The method comprises the following steps: (1) passing chlorination distillate, reaction rectification kettle liquid and light components and part of heavy component materials collected from a separation unit into a pre-chlorination reaction unit to perform pre-chlorination reaction, to obtain gas phase materials and pre-chlorination reaction liquid; According to mass percentage, the chlorination distillate comprises the following components: monochloropropanediol 0-0.1%; dichloropropanol 30%-40%; hydrogen chloride 20%-30%; glycerol 0-0.1%; water 30%-40%; According to mass percentage, the reaction rectification kettle liquid comprises the following components: monochloropropanediol 10%-15%; dichloropropanol 0-1%; glycerol 80%-85%; water 0-5%; According to mass percentage, the light components comprise the following components: dichloropropanol 20%-30%; hydrogen chloride 10%-18%; water 55%-65%; According to mass percentage, the heavy component materials comprise the following components: monochloropropanediol 10%-25%; dichloropropanol 0-10%; hydrogen chloride 0-0.5%; glycerol 0-0.5%; water 0-0.5%; the rest is catalyst and catalyst derivatives; (2) passing glycerol containing catalyst and the gas phase materials obtained in step (1) into a reaction rectification unit to perform mixing reaction, to obtain water phase materials and reaction rectification kettle liquid, and the reaction rectification kettle liquid is recycled to step (1); (3) passing hydrogen chloride and the pre-chlorination reaction liquid obtained in step (1) into a chlorination reaction unit to perform chlorination reaction, to obtain chlorination distillate and kettle chlorination liquid, and the chlorination distillate is recycled to step (1); (4) passing the kettle chlorination liquid obtained in step (3) into a separation unit, to obtain dichloropropanol, light components and heavy component materials, the dichloropropanol is prepared into epichlorohydrin through saponification, and the light components and part of the heavy component materials are recycled to step (1).

2. The method of claim 1, wherein, The pre-chlorination reaction unit in step (1) comprises three-stage pre-chlorination reactors, and the residence time of the reaction materials in each pre-chlorination reactor is independently 1-6 h.

3. The method of claim 2, wherein, The residence time of the reaction materials in each pre-chlorination reactor is independently 2-4 h.

4. The method of claim 1, wherein, According to mass percentage, the gas phase materials in step (1) comprise the following components: dichloropropanol 10%-15%; hydrogen chloride 1%-3%; water 80%-88%.

5. The method of claim 1, wherein, The mass of the gas phase materials in step (1) accounts for 18%-22% of the total mass of the pre-chlorination reaction unit feed.

6. The method of claim 1, wherein, The gas phase materials in step (2) further pass through a steady-state buffer feeder and a gas distributor in sequence before being fed into the reaction rectification unit.

7. The method of claim 1, wherein, The glycerol in step (2) is mixed with the catalyst after being preheated, and the preheating temperature is ≥80℃.

8. The method of claim 1, wherein, The catalyst in step (2) comprises a dibasic carboxylic acid catalyst, and the boiling point is ≥150℃.

9. The method of claim 1, wherein, The mass of the catalyst in step (2) accounts for 0.5%-10% of the mass of the glycerol.

10. The method of claim 9, wherein, The mass of the catalyst in step (2) accounts for 2%-8% of the mass of the glycerol.

11. The method of claim 1, wherein, The mass ratio of the glycerol containing catalyst to the reaction rectification kettle liquid in step (2) is 1:(1.1-1.2).

12. The method of claim 1, wherein, The mass ratio of the glycerol containing catalyst to the chlorination distillate in step (3) is 1:(0.5-0.6).

13. The method of claim 1, wherein, The mass ratio of the catalyst-containing glycerol in step (2) to the light component in step (4) is 1:(0.08-0.12).

14. The method of claim 1, wherein, The mass ratio of the catalyst-containing glycerol in step (2) to the heavy component material in step (4) is 1:(0.5-0.6).

15. The method of claim 1, wherein, The reaction rectification unit in step (2) comprises a reaction rectification column.

16. The method of claim 15, wherein, The bottom temperature of the reaction rectification column is 60-130℃.

17. The method of claim 16, wherein, The bottom temperature of the reaction rectification column is 120-130℃.

18. The method of claim 15, wherein, The top temperature of the reaction rectification column is 50-100℃.

19. The method of claim 18, wherein, The top temperature of the reaction rectification column is 55-75℃.

20. The method of claim 15, wherein, The internal pressure of the reaction rectification column is -85kPa to -30kPa.

21. The method of claim 15, wherein, The residence time of the material in the reaction rectification column is 0.5-2h.

22. The method of claim 15, wherein, The number of plates of the reaction rectification column is 20-45.

23. The method of claim 22, wherein, The number of plates of the reaction rectification column is 25-35.

24. The method of claim 15, wherein, The reflux ratio of the reaction rectification column is 0.5-3.

25. The method of claim 24, wherein, The reflux ratio of the reaction rectification column is 1.5-2.

5.

26. The method of claim 1, wherein, The aqueous phase material in step (2) comprises the following components in terms of mass percentage: Dichloropropanol 0-0.2%; Hydrogen chloride 0-0.3%; Water 99.5%-100%.

27. The method of claim 1, wherein, The mass ratio of the aqueous phase material in step (2) to the reaction rectification kettle liquid is 1:(3-5).

28. The method of claim 1, wherein, The chlorination reaction unit in step (3) comprises at least two stages of chlorination reactors, and hydrogen chloride and pre-chlorination reaction liquid are fed into the first stage of chlorination reactors, overflow into the next stage of chlorination reactors, and gas phase is recovered in the second stage of chlorination reactors, and the chlorination distillate of each stage of chlorination reactors is combined and uniformly recycled to step (1).

29. The method of claim 1, wherein, The mass percentage of the heavy component material in step (4) recycled to step (1) is ≥20%.

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