CN111646877A - Method for treating waste hydrochloric acid in sucralose production - Google Patents
Method for treating waste hydrochloric acid in sucralose production Download PDFInfo
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- CN111646877A CN111646877A CN202010447381.3A CN202010447381A CN111646877A CN 111646877 A CN111646877 A CN 111646877A CN 202010447381 A CN202010447381 A CN 202010447381A CN 111646877 A CN111646877 A CN 111646877A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/16—Preparation of halogenated hydrocarbons by replacement by halogens of hydroxyl groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
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Abstract
The invention relates to a method for treating waste hydrochloric acid in sucralose production, which is characterized by comprising the following steps: (1) adding 30% zinc chloride solution into a reactor, and mixing waste hydrochloric acid and methanol according to a molar ratio of 1: feeding at 0.9 ℃ to 108 ℃ and the liquid level is 80%; (2) the gas phase passes through an acid removal tower to remove most of water and most of hydrogen chloride gas, and the temperature is 95 +/-5 ℃; (3) the gas phase passes through a dealcoholization tower to remove a small amount of water and most of methanol at the temperature of 85 +/-5 ℃; (4) the gas phase passes through a desulfurizing tower to absorb methanol, a small amount of hydrochloric acid and sulfur dioxide gas; (5) and rectifying the gas phase by a rectifying tower, pressurizing and condensing, and drying by a molecular sieve to obtain the chloromethane. The invention has the advantages that: 1. methanol has better selectivity than ethanol; the reaction temperature is lower; the reaction yield is high, the side reaction is less, and the rectification waste liquid is less; 2. methanol with any concentration can be recycled to the system for reaction, unlike ethanol which has extremely high requirements and has greater cost advantage.
Description
Technical Field
The invention belongs to the technical field of chemical production, and relates to a method for treating waste hydrochloric acid in sucralose production.
Background
Sucralose (Sucralose or TGS CNS: 19.016; INS: 955), also known as Sucralose, saccharan or 4,1, 6, -trichloro-4, 1, 6, -trideoxy-semimilk sucrose, the english name: Sucralose. Sucralose is prepared by chlorination of sucrose as a raw material. Hydrochloric acid (Hydrochloric acid) molecular formula HCl, relative molecular mass 36.46. The hydrochloric acid is aqueous solution of hydrogen chloride with different concentrations, is transparent and colorless or yellow, and has pungent odor and strong corrosivity. In the high-temperature chlorination process, thionyl chloride is used as a chlorinating agent, hydrogen chloride and sulfur dioxide tail gas are mainly generated and absorbed by tertiary water to form hydrochloric acid aqueous solution. The traditional method is as follows: 1. selling the hydrochloric acid to printing and dyeing enterprises and metal processing enterprises; 2. many enterprises use sodium hydroxide and potassium hydroxide for neutralization, but the enterprises cannot completely consume the hydrochloric acid due to the large amount of impurities and large amount of impurities, so that the hydrochloric acid in a production system is sometimes stored in a vacant place, and the treatment methods are not long-term, can cause abnormal operation of production, and further increase the production cost of the enterprises. The treatment method can protect the environment and further reduce the production cost of the sucralose.
Patent publication No. CN109438169A proposes a method for recovering waste hydrochloric acid generated in sucralose production by using ethanol and waste hydrochloric acid to perform substitution reaction under the catalysis of zinc chloride to generate halogenated hydrocarbon and water, and preparing finished chloromethane after deacidification, dealcoholization, alkaline washing and dehydration, wherein the ethanol is required to be absolute ethanol and has higher cost; and the hydrochloric acid and the ethanol have the problems of more side reactions and low reaction yield when the reaction is carried out under the condition of zinc chloride catalysis.
Disclosure of Invention
The invention aims to solve the problems and provides a method for treating waste hydrochloric acid in sucralose production; the waste hydrochloric acid in the method is formed by absorbing tail gas generated by high-temperature chlorination reaction of sucralose with water, has the characteristics of more impurities, strong irritation, difficulty in treatment and the like, utilizes the substitution reaction of methanol and the waste hydrochloric acid under the catalysis of zinc chloride to generate halogenated hydrocarbon and water, prepares the finished product methyl chloride after deacidification, dealcoholization, alkali washing and dehydration, and generates the methyl chloride with the water content lower than 100ppm and the purity higher than 99.5 percent through reaction, thereby achieving the purposes of reducing the hydrochloric acid content of aqueous solution, recycling the aqueous solution to a system, ensuring normal operation of sucralose production and reducing the production cost.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for treating waste hydrochloric acid in sucralose production is characterized by comprising the following steps:
(1) adding 30% zinc chloride solution into a reactor, and mixing waste hydrochloric acid and methanol according to a molar ratio of 1: 0.9, feeding in a mixed manner, heating while adding, controlling the temperature of the reactor to be 105-108 ℃, and controlling the liquid level of the reactor to be 80%;
(2) the gas phase passes through an acid removal tower to remove most of water and most of hydrogen chloride gas in the gas phase, and the temperature is controlled at 115 +/-5 ℃;
(3) the gas phase passes through a dealcoholization tower to remove a small amount of water and most of methanol, and the temperature is controlled at 105 +/-5 ℃;
(4) the gas phase passes through a desulfurizing tower to absorb methanol, a small amount of hydrochloric acid and sulfur dioxide gas in the gas phase;
(5) rectifying the gas phase in a rectifying tower, pressurizing to 0.5-0.8MPa, condensing at 20-25 deg.c, and drying with molecular sieve to obtain methyl chloride.
Further, the reaction temperature in the step (1) is preferably 106-107 ℃.
Compared with the prior art, the invention has the following advantages:
1. compared with ethanol, the methanol reacts with hydrochloric acid under the catalysis of zinc chloride, so that the selectivity is better, and the use amount of the methanol is reduced by 30 percent compared with that of the ethanol; the reaction temperature is lower (from the original 138 ℃ to 105-108 ℃), and the energy can be saved by 20-30%; high reaction yield (increased from 85% to 95%), less side reactions, and less rectification waste liquid (reduced by 50m compared with ethanol)3）；
2. Methanol with any concentration can be recycled to the system for reaction, unlike ethanol which has extremely high requirements (absolute ethanol), methanol has a greater cost advantage compared with ethanol, and can save 800 ten thousand yuan per year.
Detailed Description
A method for treating waste hydrochloric acid in sucralose production comprises the following specific implementation steps:
example one:
in the volume of 17m3Adding a zinc chloride solution with the concentration of 30% in the reactor for carrying out 2m ethanol cultivation, and carrying out 1m ethanol cultivation on the waste hydrochloric acid and methanol according to the flow ratio: 0.9m thin strip/h pumped into the mixer and into the reactor, heater (350 m)2) Heating, controlling the temperature of the reactor at 108 ℃, and controlling the liquid level of the reactor at 80%; the discharged gas phase firstly passes through a gas-liquid separator in 10m and a deacidification tower in 21.4m to remove most of water and most of hydrogen chloride gas in the gas phase, the temperature is controlled at 105 +/-5 ℃ by a tower bottom circulating pump, and dilute hydrochloric acid (the concentration is about 3%) is fed back to a sucralose chlorination section to absorb the hydrogen chloride gas; passing gas phase through dealcoholization tower at 21.4m for removing small amount of water and most of methanol, controlling temperature at 95 + -5 deg.C by circulating pump at bottom of tower, and pumping methanol (content of about 10%) to methanol recovering tower for recovering methanol; the gas phase passes through a desulfurizing tower for 12m heavy year to absorb a small amount of methanol, a small amount of hydrochloric acid and sulfur dioxide gas in the gas phase; and then rectifying the gas phase by a rectifying tower with the length of 51.9m to remove a small amount of methanol, pressurizing and condensing, and drying by a molecular sieve to obtain the methyl chloride with the purity of 99.5 percent.
Example two:
performing a 15 m high pressure swing at a volume of 17m, loading a 30% zinc chloride solution at a volume of 2m, and carrying out a 1m high pressure swing on spent hydrochloric acid and methanol at a flow ratio: 0.8m thin strip/h pumped into the mixer and into the reactor, heater (350 m)2) Heating, controlling the temperature of the reactor at 115 ℃ and the liquid level of the reactor at 70%; the discharged gas phase firstly passes through a gas-liquid separator in 10m and a deacidification tower in 21.4m to remove most of water and most of hydrogen chloride gas in the gas phase, the temperature is controlled at 110 +/-5 ℃ by a tower bottom circulating pump, and dilute hydrochloric acid (the concentration is about 4%) is fed back to a sucralose chlorination section to absorb the hydrogen chloride gas; passing the gas phase through a dealcoholization tower at 21.4m for removing a small amount of water and most of methanol, controlling the temperature at 103 + -2 deg.C by a circulating pump at the bottom of the tower, and pumping methanol (with content of about 5%) to a methanol recovery tower for recovering methanol; the gas phase is subjected to desulfurization tower for 12m high-speed harvest to absorb a small amount of methanol, a small amount of hydrochloric acid and sulfur dioxide in the gas phaseA gas; and then rectifying the gas phase by a rectifying tower with the length of 51.9m to remove a small amount of methanol, pressurizing and condensing, and drying by a molecular sieve to obtain the methyl chloride with the purity of 99.9 percent.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.
Claims (3)
1. A method for treating waste hydrochloric acid in sucralose production is characterized by comprising the following steps:
(1) adding 30% zinc chloride solution into a reactor, and mixing waste hydrochloric acid and methanol according to a molar ratio of 1: 0.9, feeding in a mixed manner, heating while adding, controlling the temperature of the reactor to be 105-108 ℃, and controlling the liquid level of the reactor to be 80%;
(2) the gas phase passes through an acid removal tower to remove most of water and most of hydrogen chloride gas in the gas phase, and the temperature is controlled at 115 +/-5 ℃;
(3) the gas phase passes through a dealcoholization tower to remove a small amount of water and most of methanol, and the temperature is controlled at 105 +/-5 ℃;
(4) the gas phase passes through a desulfurizing tower to absorb methanol, a small amount of hydrochloric acid and sulfur dioxide gas in the gas phase;
(5) and (3) rectifying the gas phase by a rectifying tower, pressurizing and condensing, and drying by a molecular sieve to obtain the chloromethane.
2. The method for treating waste hydrochloric acid in sucralose production according to claim 1, wherein the method comprises the following steps: in the step (1), the reaction temperature is preferably 106-107 ℃.
3. The method for treating waste hydrochloric acid in sucralose production according to claim 1, wherein the method comprises the following steps: the operation conditions of the step (5) of pressurizing and condensing are that the pressure is 0.5-0.8Mpa and the temperature is 20-25 ℃.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010447381.3A CN111646877A (en) | 2020-05-25 | 2020-05-25 | Method for treating waste hydrochloric acid in sucralose production |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010447381.3A CN111646877A (en) | 2020-05-25 | 2020-05-25 | Method for treating waste hydrochloric acid in sucralose production |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2026131A (en) * | 1933-02-15 | 1935-12-31 | Ig Farbenindustrie Ag | Production of methyl chloride |
| GB1142351A (en) * | 1965-03-23 | 1969-02-05 | Allied Chem | Process for the production of chloromethanes |
| US6111153A (en) * | 1999-06-01 | 2000-08-29 | Dow Corning Corporation | Process for manufacturing methyl chloride |
| CN102718623A (en) * | 2012-07-13 | 2012-10-10 | 自贡鸿鹤化工股份有限公司 | Method of producing methane chloride by using byproduct hydrogen chloride of tetrachloroethylene device |
| CN103435438A (en) * | 2013-08-08 | 2013-12-11 | 顾志祥 | Production method of methane chloride |
| CN109438169A (en) * | 2018-12-10 | 2019-03-08 | 安徽金禾实业股份有限公司 | The processing method of waste hydrochloric acid in a kind of production of Sucralose |
-
2020
- 2020-05-25 CN CN202010447381.3A patent/CN111646877A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2026131A (en) * | 1933-02-15 | 1935-12-31 | Ig Farbenindustrie Ag | Production of methyl chloride |
| GB1142351A (en) * | 1965-03-23 | 1969-02-05 | Allied Chem | Process for the production of chloromethanes |
| US6111153A (en) * | 1999-06-01 | 2000-08-29 | Dow Corning Corporation | Process for manufacturing methyl chloride |
| CN102718623A (en) * | 2012-07-13 | 2012-10-10 | 自贡鸿鹤化工股份有限公司 | Method of producing methane chloride by using byproduct hydrogen chloride of tetrachloroethylene device |
| CN103435438A (en) * | 2013-08-08 | 2013-12-11 | 顾志祥 | Production method of methane chloride |
| CN109438169A (en) * | 2018-12-10 | 2019-03-08 | 安徽金禾实业股份有限公司 | The processing method of waste hydrochloric acid in a kind of production of Sucralose |
Non-Patent Citations (1)
| Title |
|---|
| 上海科学技术情报研究所: "《国外石油化工原料和产品》", 30 November 1979, 上海科学技术文献出版社 * |
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