Hydroxylamine free base, and preparation method and reaction system therefor

Abstract

A hydroxylamine free base, and a preparation method and reaction system therefor. The reaction system comprises a rectification column (1), a heating device (2), and a condensation device (3). A catalyst loading section (11) is provided in the rectification column (1), a hydrogen peroxide feed port (12) is provided on a side wall of the rectification column (1) above the catalyst loading section, and an ammonia feed port (13) is provided on the side wall of the rectification column (1) below the catalyst loading section (11). The heating device (2) is used for heating the reboiler of the rectification column (1); the condensation device (3) communicates with the top of the rectification column (1) and is used for condensing steam flowing out of the top of the rectification column (1) and for controlling the reflux ratio of the rectification column (1).

Description

Hydroxylamine free base and its preparation method and reaction system Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to hydroxylamine free base and its preparation method and reaction system. Background Technology

[0002] Hydroxylamine free base (NH₂OH, or HAFB) is an aqueous solution of hydroxylamine with extremely low metal ion content and a pH of 10-11. It is widely used in chip cleaning solutions, as a stabilizer in lyocell fiber production, and is also an important intermediate in fine chemicals and organic synthesis. Due to the extremely unstable chemical properties of free hydroxylamine, literature reports that a 50 wt.% electronic grade HAFB aqueous solution begins to decompose above 133-136℃. The higher the hydroxylamine concentration and the higher the metal ion content in the aqueous solution, the lower the initial decomposition temperature. When the concentration of hydroxylamine aqueous solution exceeds 80 wt.% and the concentration of metal ion salts is very high, it is prone to violent decomposition and even explosion at relatively low temperatures. Because hydroxylamine decomposes in alkaline media and at high temperatures and concentrations, it is usually produced, transported, and used in the form of salts. The main hydroxylamine salts on the market are hydroxylamine sulfate, hydroxylamine hydrochloride, and hydroxylamine phosphate.

[0003] HAFB aqueous solutions used as chip cleaning solutions and stabilizers in lyocell fiber production have extremely strict requirements for metal ion content. For industrial-grade HAFB aqueous solutions (lyocell fiber stabilizers, pharmaceuticals), the sodium ion content must be less than 10 ppm and the iron ion content must be less than 0.05 ppm; for electronic-grade HAFB aqueous solutions, the content of a single metal ion must be less than 20 ppb, or even less than 10 ppb, and the chloride ion content must be less than 1 ppm.

[0004] For over 30 years, numerous companies and research institutions worldwide have dedicated themselves to researching safe and environmentally friendly preparation processes for HAFB aqueous solutions. Currently, there are two main technical routes for preparing HAFB aqueous solutions. The first step in both routes is a neutralization reaction between hydroxylamine sulfate, hydroxylamine hydrochloride, or hydroxylamine phosphate and an alkali (such as NaOH, calcium oxide, ammonia, etc.) to generate a saturated aqueous solution of the corresponding inorganic salt of free hydroxylamine. Subsequently, two different purification methods are used to desalinate the solution, resulting in an HAFB aqueous solution with extremely low metal ion content.

[0005] The first purification method is the distillation desalting purification technology route. A saturated aqueous solution of inorganic salts containing a certain concentration of free hydroxylamine is distilled and desalted to obtain a 50 wt.% HAFB aqueous solution. Since the boiling point of hydroxylamine (120℃) is higher than that of water (100℃), when the vapor composition of a certain section of the distillation column or the top of the column reaches a hydroxylamine concentration of 50 wt.% or higher, the composition of the bottom material will definitely be an aqueous solution of hydroxylamine with a concentration greater than 50 wt.%. Furthermore, because a large amount of inorganic salt solids produced by distillation and concentration exist in the bottom of the column, it will severely hinder the mass and heat transfer of the hydroxylamine aqueous solution in the bottom of the column, and may cause local overheating and excessively high hydroxylamine concentration in the bottom of the column. If the process conditions are not properly controlled and the on-site operation is improper, a safety accident can easily occur. Furthermore, these inorganic salts contain hydroxylamine residues on their surface, which are classified as hazardous waste, posing safety and environmental risks. Their disposal costs are high, and the presence of high concentrations of inorganic salts such as NaCl, Na2SO4, CaCl2, and CaSO4 can significantly lower the decomposition temperature of hydroxylamine, accelerate the decomposition reaction, increase the risk of safety accidents, and reduce the yield of hydroxylamine.

[0006] The second purification method is the ion exchange resin desalination purification technology. Since it processes saturated inorganic salt solutions or hydroxylamine salt solutions, the ion exchange resin must be regenerated extremely frequently. Each regeneration requires more than six times the resin volume of hydrochloric acid and NaOH solution, resulting in a very large amount of waste hydrochloric acid and waste sodium hydroxide solution. This leads to very high production costs and severe environmental pollution. Currently, there are no reports of this purification method being used for industrial-scale production.

[0007] BASF of Germany uses the first purification method – distillation and desalting – to industrially produce HAFB products, and is the only company in the world that can safely control this hazardous production process.

[0008] CN13193212B discloses a method for preparing HAFB, in which a Ti-MOR catalyst, an aqueous solution of tert-butanol, and ammonia are mixed in a reactor at a weight ratio of 1:20-170:6-600 to form a reaction system. The aqueous solution of tert-butanol is a mixture of tert-butanol and pure water at a weight ratio of 1:1-10. The reaction temperature is 40-80℃. Hydrogen peroxide is added in one step or dropwise, with the ratio of hydrogen peroxide to catalyst being 3-10:1, to obtain a crude product of free hydroxylamine solution with a mass concentration of 0.15-10%. In this reaction, since hydroxylamine can be further oxidized by hydrogen peroxide under the action of the catalyst to produce strong carcinogens such as nitrogen oxides, nitrates, and nitrites, the amount of ammonia added must be significantly excessive. At the same time, the concentration of hydrogen peroxide added is low to reduce the influence of localized excessive concentration of hydrogen peroxide during dropwise addition, so as to inhibit the oxidation reaction between hydrogen peroxide and hydroxylamine. The crude product contains excessive amounts of ammonia, significant concentrations of the potent carcinogens nitrite and nitrate, low concentrations of hydroxylamine, and an aqueous solution of tert-butanol, greatly increasing the difficulty, energy consumption, and production costs of subsequent separation, purification, and concentration. Furthermore, contact between hydroxylamine and titanium metal or titanium ions triggers its decomposition reaction, generating ammonia, nitrogen, and nitrogen oxides. During the reaction, the titanium-silicon molecular sieve catalyst, while catalyzing the reaction of ammonia with hydrogen peroxide to produce hydroxylamine, also triggers the decomposition reaction of hydroxylamine, leading to a decrease in hydroxylamine yield.

[0009] In conclusion, there are significant obstacles to the industrialization of this technology. Summary of the Invention

[0010] The main objective of this invention is to provide a hydroxylamine free base and its preparation method and reaction system, so as to overcome the defects of existing technologies such as dangerous and difficult-to-control hydroxylamine free base preparation processes, numerous by-products, and low hydroxylamine yield.

[0011] To achieve the above objectives, the present invention provides a reaction system for preparing a hydroxylamine free base, comprising:

[0012] A distillation column, wherein a catalyst loading section is provided inside the distillation column, a hydrogen peroxide inlet is provided on the side wall of the distillation column above the catalyst loading section, and an ammonia inlet is provided on the side wall of the distillation column below the catalyst loading section.

[0013] A heating device for heating the reboiler of the distillation column;

[0014] A condenser, connected to the top of the distillation column, is used to condense the vapor flowing out from the top of the distillation column and to control the reflux ratio of the distillation column.

[0015] In one embodiment of the reaction system for preparing hydroxylamine free base according to the present invention, the ammonia inlet and the column bottom are filled with distillation packing or provided with a column tray, wherein the number of the column trays is greater than or equal to 5 layers or filled with distillation packing equivalent to 5 layers or more of column trays.

[0016] In one embodiment of the reaction system for preparing hydroxylamine free base according to the present invention, the distillation column is equipped with a pressure monitoring device at the top to monitor the pressure inside the distillation column; the catalyst loading section is equipped with a temperature monitoring device to monitor the temperature of the catalyst loading section; and the reboiler is equipped with an online spectroscopic sensor to monitor the hydrogen peroxide content in the reboiler liquid; the catalyst loaded in the catalyst loading section is a catalyst that catalyzes the oxidation reaction of hydrogen peroxide. In another embodiment of the reaction system for preparing hydroxylamine free base according to the present invention, a control device is further included, connected to the pressure monitoring device at the top of the distillation column, the temperature monitoring device in the catalyst loading section, the online spectroscopic sensor in the reboiler, and a condensation device, to monitor and adjust the pressure at the top of the distillation column, the temperature of the catalyst loading section, the hydrogen peroxide content in the reboiler liquid, and the reflux ratio in real time.

[0017] To achieve the above objectives, the present invention also provides a reaction apparatus for preparing a hydroxylamine free base, comprising:

[0018] A distillation column, wherein a catalyst loading section is provided inside the distillation column, a hydrogen peroxide inlet is provided on the side wall of the distillation column above the catalyst loading section, and an ammonia inlet is provided on the side wall of the distillation column below the catalyst loading section.

[0019] A heating device for heating the reboiler of the distillation column;

[0020] A condenser, connected to the top of the distillation column, is used to condense the vapor flowing out from the top of the distillation column;

[0021] The control device is connected to the pressure monitoring device at the top of the distillation column, the temperature monitoring device in the catalyst packing section, and the online spectral sensor in the bottom of the column to monitor and adjust the pressure at the top of the distillation column, the temperature in the catalyst packing section, and the hydrogen peroxide content in the liquid in the bottom of the column in real time.

[0022] In one embodiment of the reaction apparatus for preparing hydroxylamine free base according to the present invention, the ammonia inlet and the reboiler are filled with distillation packing or a tray is provided, and the number of trays is greater than or equal to 5.

[0023] In one embodiment of the reaction apparatus for preparing hydroxylamine free base according to the present invention, a pressure monitoring device installed at the top of the distillation column is used to monitor the pressure inside the distillation column; a temperature monitoring device installed in the catalyst loading section is used to monitor the temperature of the catalyst loading section; an online spectral sensor installed in the bottom of the column is used to monitor the hydrogen peroxide content in the bottom liquid; and / or, the catalyst loaded in the catalyst loading section is a catalyst that can catalyze the oxidation reaction of hydrogen peroxide.

[0024] To achieve the above objectives, the present invention further provides a method for preparing a hydroxylamine free base, comprising the following steps:

[0025] Step 1: A catalyst is loaded into a distillation column, ammonia is introduced below the catalyst, and hydrogen peroxide is introduced above the catalyst. The temperature at the catalyst is controlled at 40-100℃, and the pressure inside the distillation column is 0.1-0.2 atm. The ammonia and hydrogen peroxide react under the action of the catalyst to generate hydroxylamine free base.

[0026] Step 2: The hydroxylamine free base flows downward into the bottom of the distillation column and is continuously enriched;

[0027] The catalyst is a catalyst that catalyzes the oxidation reaction of hydrogen peroxide.

[0028] In one embodiment of the method for preparing hydroxylamine free base according to the present invention, the catalyst is a titanium silicate molecular sieve or an iron-based oxide catalyst modified with Hβ-80 zeolite. In addition, all catalysts that can catalyze the oxidation reaction of hydrogen peroxide can be used.

[0029] In one embodiment of the method for preparing hydroxylamine free base according to the present invention, the hydrogen peroxide is calculated as hydrogen peroxide, and the feed molar ratio of hydrogen peroxide to ammonia is 1.0:1.0-1.2; the hydrogen peroxide further includes an organic solvent, and the ammonia further includes water and / or an organic solvent, wherein the organic solvent is at least one selected from methanol, ethanol, n-propanol, isopropanol, tert-butanol, n-butanol, and isobutanol.

[0030] In one embodiment of the method for preparing hydroxylamine free base according to the present invention, the temperature of the bottom of the distillation column is 40-120°C. The ammonia in the bottom of the column rises due to heating. The vapor at the top of the distillation column condenses into liquid and returns to the distillation column to participate in the reaction again at the catalyst.

[0031] In one embodiment, the method for preparing hydroxylamine free base according to the present invention further includes drawing out the crude reaction product containing hydroxylamine from the bottom of a distillation column, removing ammonia and part of the water from the crude reaction product, and obtaining hydroxylamine free base.

[0032] To achieve the above objectives, the present invention further provides a hydroxylamine free base prepared by the above method.

[0033] The beneficial effects of this invention are:

[0034] This invention utilizes a distillation column to prepare free hydroxylamine from hydrogen peroxide and ammonia through a distillation process. By leveraging the boiling point difference between water, ammonia, and hydroxylamine, the reaction is not only promoted and further reaction between hydrogen peroxide and hydroxylamine is avoided, but also the decomposition of hydroxylamine caused by metals in the catalyst is prevented. This results in the enrichment of pure hydroxylamine in the distillation column, improving the purity and yield of free hydroxylamine. Furthermore, this method eliminates the need for excessive ammonia, thus preventing the formation of nitrites and nitrates in the free hydroxylamine. This also avoids excessively high ammonia content in the free hydroxylamine, significantly reducing the difficulty of subsequent purification.

[0035] The method of this invention is low in cost, has a high yield of hydroxylamine, generates almost no waste, is environmentally friendly, and is suitable for industrial production. Attached Figure Description

[0036] Figure 1 is a schematic diagram of the reaction system in one embodiment of the present invention.

[0037] Figure 2 is a cross-sectional view of a distillation column according to one embodiment of the present invention.

[0038] Figure 3 is a connection module diagram of the control device in a reaction system according to one embodiment of the present invention.

[0039] Figure 4 is a connection module diagram of the control device in the reaction system according to another embodiment of the present invention.

[0040] Figure 5 is a schematic diagram of temperature control inside the distillation column according to one embodiment of the present invention.

[0041] Figure 6 is a schematic diagram of pressure control inside the distillation column according to one embodiment of the present invention.

[0042] Figure 7 is a schematic diagram of hydrogen peroxide content control in the bottom of a distillation column according to an embodiment of the present invention.

[0043] In the attached figures, the following labels are used:

[0044] 1. Distillation column

[0045] 11 Catalyst loading section

[0046] 12. Hydrogen peroxide inlet

[0047] 13 Ammonia Inlet

[0048] 14. Distillation packing

[0049] 15 Pressure monitoring device

[0050] 16 Temperature monitoring device

[0051] 17 Online Spectral Sensors

[0052] 2 Heating device

[0053] 3. Condensation device Detailed Implementation

[0054] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0055] This invention utilizes the property that the boiling points of ammonia and water are significantly lower than those of hydroxylamine, enabling the reaction of ammonia and hydrogen peroxide within a distillation column. This allows for the rapid separation of the generated hydroxylamine from the catalyst and reactants, thus accelerating the reaction and preventing side reactions between the hydroxylamine product and the reactants, as well as the decomposition of the hydroxylamine product under the action of the catalyst. Furthermore, in this method, the ammonia feedstock does not require a significant excess, resulting in very low levels of nitrite, nitrate, and ammonia in the reaction products, greatly reducing the difficulty, energy consumption, and cost of subsequent purification and concentration. Using the process and method of this invention, free hydroxylamine bases with a total metal ion content of less than 1 ppm and a concentration of 50 wt.% or higher can be prepared in high yield.

[0056] In one embodiment, the present invention provides a reaction system for preparing hydroxylamine free bases, which can be used for the preparation of hydroxylamine free bases of the present invention to achieve the above-mentioned effects. Specifically, the reaction system for preparing hydroxylamine free bases of the present invention is shown in FIG1, including a distillation column 1, a heating device 2, and a condensing device 3.

[0057] In this invention, the distillation column 1 can be a distillation column used in industrial production, or it can be a device based on the principle of distillation, such as a laboratory-scale simulated distillation column. The distillation column 1 of this invention is equipped with a catalyst loading section 11, which is filled with catalyst. A hydrogen peroxide inlet 12 is located on the side wall of the distillation column 1 above the catalyst loading section 11, and an ammonia inlet 13 is located on the side wall of the distillation column 1 below the catalyst loading section 11. A heating device 2 is used to heat the bottom of the distillation column 1. A condensing device 3 is connected to the top of the distillation column 1 and is used to condense the vapor flowing out from the top of the distillation column 1 and to control the reflux ratio of the distillation column 1.

[0058] The present invention does not impose any particular limitation on the location of the catalyst packing section 11 in the distillation column 1, for example, it can be located in the upper middle part of the distillation column 1. In one embodiment, the area between the ammonia inlet 13 and the reboiler is a stripping section, which is packed with distillation packing 14 or provided with trays (not shown), but the present invention is not limited thereto. The present invention does not impose any particular limitation on the amount of distillation packing 14 packed, for example, equivalent to or greater than 5 theoretical trays, further equivalent to or greater than 10 theoretical trays and less than 100 theoretical trays, and the number of trays provided is greater than or equal to 5, further greater than or equal to 10 and less than 100. As the amount of distillation packing 14 increases and the number of theoretical trays increases, the purity of the product in the reboiler is higher. If there is no stripping section packed with distillation packing 14 or trays, the reaction effect is also good, but slightly worse than the reaction system with a stripping section. The present invention does not impose any particular limitation on the type of distillation packing 14, and those skilled in the art can make conventional selections as needed.

[0059] In the reaction system of this invention, the catalyst loaded in the catalyst loading section 11 is a catalyst capable of catalyzing the oxidation reaction of hydrogen peroxide. This invention does not impose any particular limitation on the catalyst, as long as it can catalyze the oxidation reaction of hydrogen peroxide. It can be a titanium silicate molecular sieve, such as TS-1 molecular sieve, or an iron-based oxide catalyst modified with Hβ-80 zeolite, such as the catalyst prepared according to the method disclosed in "A High-Performance Composite Oxide Catalyst for Phenol Hydroxylation" (Zhang Xinfang et al., Fine Chemicals, 2005, 22(5): 369-372). Of course, it can also be other catalysts disclosed in the prior art for hydrogen peroxide oxidation, such as the catalyst disclosed in "Research on Catalysts for Direct Hydroxylation of Phenol and Hydrogen Peroxide" (Zhu Yanjing, Master's Thesis, Zhejiang Normal University, 2009). When the catalyst selected in this invention is a titanium silicate molecular sieve, this invention does not particularly limit the specific type of titanium silicate molecular sieve, and it can be TS-1 molecular sieve, TS-2 molecular sieve, TS-Beta molecular sieve, etc.

[0060] In one embodiment, the catalyst of the present invention is first prepared into catalyst particles, and then loaded into the catalyst loading section 11. The present invention does not particularly limit the method of preparing the catalyst particles; for example, spherical particles can be prepared using a binder, or columnar particles can be prepared by tableting.

[0061] The heating device 2 is used to heat the reboiler of the distillation column 1. This invention does not particularly limit the form of the heating device 2, as long as it can achieve the purpose of heating the reboiler of the distillation column 1. The heating device 2 can directly heat the reboiler, raising the temperature of the liquid inside; alternatively, the liquid inside the reboiler can be transferred to the heating device 2, heated by the heating device 2, and then the liquid can be transferred back to the reboiler, thereby achieving the purpose of heating the reboiler. The reboiler temperature (the temperature of the liquid inside the reboiler) is, for example, 40-120°C.

[0062] The condenser 3 is connected to the top of the distillation column 1 and is used to condense the vapor flowing out from the top of the distillation column 1 and to control the reflux ratio of the distillation column 1. The present invention does not impose any particular limitation on the condenser 3, as long as it can condense the vapor, and the condensed vapor is partially or completely returned to the distillation column 1. In one embodiment, when the distillation column 1 is operated intermittently, it is under total reflux during the reaction period, and the reflux ratio during the deammoniation, dehydration, and concentration stage after the reaction is completed can be adjusted to ≥1; when the distillation column 1 is operated continuously, it is under total reflux.

[0063] In one embodiment, as shown in Figure 2, a pressure monitoring device 15 is installed at the top of the distillation column 1 to monitor the pressure inside the distillation column 1, for example, controlling the pressure inside the distillation column 1 to be 0.1-0.2 atm; a temperature monitoring device 16 is installed in the catalyst loading section 11 to monitor the temperature of the catalyst loading section 11, for example, controlling it to be 40-100°C, and further, it can be controlled to be 50-70°C. In another embodiment, an online spectral sensor 17 is installed in the bottom of the column to monitor the hydrogen peroxide content in the bottom liquid.

[0064] This invention does not specifically limit the control method of the reaction system used to prepare hydroxylamine free base. The parameters of the reaction system can be manually controlled or automatically controlled. In one embodiment, as shown in FIG3, the reaction system for preparing hydroxylamine free base of this invention further includes a control device connected to a pressure monitoring device 15 at the top of the distillation vessel 1, a temperature monitoring device 16 in the catalyst loading section 11, and an online spectral sensor 17 in the reboiler, to monitor and adjust the pressure at the top of the distillation vessel 1, the temperature of the catalyst loading section 11, and the hydrogen peroxide content in the reboiler liquid in real time. In another embodiment, as shown in FIG4, the control device is also connected to a condenser 3 to monitor and adjust the reflux ratio of the condenser 3 in real time.

[0065] In this invention, hydrogen peroxide enters the distillation column 1 through hydrogen peroxide inlet 12, and ammonia enters the distillation column 1 through ammonia inlet 13, wherein the ammonia enters, for example, in liquid ammonia form. The high-boiling-point hydrogen peroxide flows downwards, while the low-boiling-point ammonia rises. The two come into contact in the catalyst loading section 11 and react under the action of the catalyst to generate high-boiling-point hydroxylamine (NH₂OH). Due to the distillation effect, the high-boiling-point hydroxylamine continuously flows downwards in liquid form, thus allowing it to leave the catalyst loading section 11 in a timely manner. This causes the chemical equilibrium between hydrogen peroxide and ammonia to continuously shift towards hydroxylamine formation, accelerating the reaction rate of hydrogen peroxide oxidizing ammonia to hydroxylamine. Simultaneously, the timely separation of hydroxylamine from the catalyst avoids oxidation side reactions between hydroxylamine and hydrogen peroxide under the action of the catalyst, and also avoids hydroxylamine decomposition side reactions initiated by metal elements in the catalyst.

[0066] In this invention, the generated hydroxylamine flows into the bottom of the distillation column and continuously accumulates. Unreacted ammonia in the bottom aqueous solution evaporates under the heating device 2 and re-enters the catalyst loading section 11 to participate in the reaction. Unreacted ammonia and rising water vapor inside the column are condensed by the condensing device 3 to form ammonia water of a certain concentration, which flows back into the distillation column 1 and re-enters the catalyst loading section 11 to participate in the reaction. Therefore, most of the excess ammonia and newly added ammonia in the reaction system, in the form of ammonia water of a certain concentration, are concentrated in the catalyst loading section 11 of the distillation column 1 to participate in the reaction. Therefore, in this invention, ammonia does not need to be excessively added; only a molar ratio of ammonia to hydrogen peroxide in the feed needs to be 1 or slightly higher, i.e., the amount of ammonia added is slightly excessive. Under the distillation effect, this results in a very high molar ratio of ammonia to hydrogen peroxide in the catalyst loading section 11. This accelerates the reaction rate of ammonia oxidation to hydroxylamine, ensuring that the hydrogen peroxide is completely consumed in the catalyst loading section 11 in a short time, without leaving high-concentration hydrogen peroxide residue in the crude HAFB product in the bottom of the column. On the other hand, it can also effectively suppress the side reaction of hydrogen peroxide oxidizing hydroxylamine under the action of the catalyst, resulting in a high yield and high concentration of the target product HAFB. At the same time, since the ammonia is only slightly excessive, the ammonia content in the entire reaction system is not high, and no external metal ions are added to the reaction system. Therefore, the content of various metal ions, anions, nitrites, nitrates, and ammonia in the crude HAFB product is very low, which greatly reduces the difficulty, energy consumption, and cost of subsequent purification and concentration.

[0067] When the reaction system of this invention is used to prepare hydroxylamine free base, it can be carried out continuously or intermittently, and those skilled in the art can choose according to their needs. The reflux ratio during the reaction process can also be selected as needed; a fixed reflux ratio can be used, or the reflux ratio can be adjusted during the reaction.

[0068] In one embodiment, the hydrogen peroxide, calculated as hydrogen peroxide, has a feed molar ratio of hydrogen peroxide to ammonia of 1.0:1.0-1.2. In another embodiment, the hydrogen peroxide entering through the hydrogen peroxide inlet also includes an organic solvent, which is a water-soluble organic solvent with a low boiling point. The organic solvent is, for example, at least one selected from methanol, ethanol, n-propanol, isopropanol, tert-butanol, n-butanol, and isobutanol. The ammonia entering through the ammonia inlet 13 also includes water and / or an organic solvent, which is also a water-soluble organic solvent with a low boiling point. The organic solvent is, for example, at least one selected from methanol, ethanol, n-propanol, isopropanol, tert-butanol, n-butanol, and isobutanol.

[0069] This invention does not particularly limit the concentration of hydrogen peroxide in hydrogen peroxide solution, nor does it particularly limit the ratio of water to organic solvent in hydrogen peroxide solution. In one embodiment, the concentration of hydrogen peroxide in hydrogen peroxide solution is, for example, 10 wt.% to 50 wt.%. This invention does not particularly limit the concentration of ammonia in ammonia solution, nor does it particularly limit the ratio of water to organic solvent in ammonia solution.

[0070] This invention can control the concentration of hydroxylamine in the reactor by adjusting the concentration of the raw material hydrogen peroxide, for example, to make it less than 55 wt.%. Furthermore, this invention can control the reactor temperature and the catalyst loading section 11 temperature by adjusting the feed rates of hydrogen peroxide and ammonia, and the heating rate of the heating device, to avoid excessively high hydroxylamine concentrations in the reactor, such as 80 wt.%, and excessively high reactor temperatures, such as above 133°C, thereby preventing accidents such as explosions caused by the decomposition reaction of hydroxylamine and ensuring the safe operation of the reaction system.

[0071] In addition, the reaction of hydrogen peroxide with ammonia to produce hydroxylamine is an exothermic reaction, while the vaporization of liquid ammonia is an endothermic reaction. The coupling of the two can reduce the possibility of temperature spikes in the catalyst loading section 11. By adjusting the amount of liquid ammonia introduced and the concentration and amount of hydrogen peroxide introduced, the temperature of the catalyst loading section 11 can be stably controlled.

[0072] In one embodiment of the present invention, an online spectroscopic sensor 17 is installed in the reboiler to monitor the hydrogen peroxide content in the reboiler liquid. It can also monitor the content of hydroxylamine, ammonia, nitrite ions, and nitrate ions in the reboiler material in aqueous solution or a mixture of water and organic solvent. In another embodiment, hydroxylamine in the reboiler material can be detected by HPLC, potentiometric titration, or refractive index; the content of nitrite ions, nitrate ions, and chloride ions can be detected by anion chromatography; the ammonia content can be detected by cation chromatography; and the metal ion content is detected by ICP-MS. If hydrogen peroxide is detected in the reboiler material, the hydrogen peroxide feed rate and the ammonia feed rate can be appropriately reduced according to the molar feed ratio to allow sufficient residence time for the hydrogen peroxide in the catalyst loading section 11 for complete reaction.

[0073] In the initial use of the reaction system of this invention, hydrochloric acid can be used for distillation under total reflux, with a concentration of, for example, 20 wt.%, to remove sodium ions and other metal ions from the glass surface. The system is then rinsed with water until the rinse water has a pH of 6-7 and a conductivity of less than 0.3 μS / cm. Before feeding, a certain amount of liquid ammonia, ammonia water, water, and a mixture of water and the aforementioned organic solvents can be added to the distillation column, heated to total reflux, and then hydrogen peroxide and ammonia are fed. In one embodiment, during the initial reaction stage, ammonia can be heated by heat exchange before being fed to distillation column 1. Once the reaction begins, the temperature of the catalyst loading section 11 gradually increases, at which point ammonia can directly enter distillation column 1 without heat exchange.

[0074] The present invention also provides a reaction apparatus for preparing a hydroxylamine free base, comprising:

[0075] A distillation column 1 is provided, wherein a catalyst loading section 11 is provided inside the distillation column 1, a hydrogen peroxide inlet 12 is provided on the side wall of the distillation column 1 above the catalyst loading section 11, and an ammonia inlet 13 is provided on the side wall of the distillation column 1 below the catalyst loading section 11.

[0076] Heating device 2 is used to heat the bottom of the distillation column 1;

[0077] The condenser 3 is connected to the top of the distillation column 1 and is used to condense the vapor flowing out from the top of the distillation column 1.

[0078] The control device is connected to the pressure monitoring device 15 at the top of the distillation column 1, the temperature monitoring device 16 of the catalyst packing section 11, and the online spectral sensor 17 of the bottom of the column, so as to monitor and adjust the pressure at the top of the distillation column 1, the temperature of the catalyst packing section 11, and the hydrogen peroxide content in the bottom liquid in real time.

[0079] The reaction equipment of this invention refers to the main apparatus used to prepare hydroxylamine free base. The reaction system of this invention includes not only the reaction equipment but also connecting pipelines and auxiliary devices such as pumps.

[0080] The present invention also provides a method for preparing hydroxylamine free base, which can use the above-mentioned reaction system or reaction equipment, and the method includes the following steps:

[0081] Step 1: A catalyst is loaded into a distillation column, ammonia is introduced below the catalyst, and hydrogen peroxide is introduced above the catalyst. The temperature at the catalyst is controlled at 40-100℃, and the pressure inside the distillation column is 0.1-0.2 atm. The ammonia and hydrogen peroxide react under the action of the catalyst to generate hydroxylamine free base.

[0082] Step 2: The hydroxylamine free base flows downward into the bottom of the distillation column and is continuously enriched.

[0083] The catalyst is one that can catalyze the oxidation reaction of hydrogen peroxide, as described in detail above, and will not be repeated here. In one embodiment, the feed molar ratio of hydrogen peroxide to ammonia is 1.0:(1.0-1.2).

[0084] In one embodiment, a hydroxylamine stabilizer, such as cyclohexanediaminotetraacetic acid, is added during the preparation of the hydroxylamine free base to reduce the decomposition reaction of hydroxylamine.

[0085] As shown in Figures 5, 6, and 7, when preparing hydroxylamine free base using the above reaction system, the pressure monitoring device 15, temperature monitoring device 16, and online spectral sensor 17 can feed the monitoring data back to the control device in real time. The control device can adjust the hydrogen peroxide feed rate, liquid ammonia feed rate, and heating temperature of the heating device 2 in the distillation column 1 according to the monitoring data, thereby regulating the pressure at the top of the distillation vessel 1, the temperature of the catalyst packing section 11, and the hydrogen peroxide content in the liquid at the bottom of the column. Specifically, as shown in Figure 5, the temperature of the catalyst packing section 11 in the distillation column can be controlled between 40-100℃ by adjusting the hydrogen peroxide feed rate, liquid ammonia feed rate, and heating temperature of the heating device 2. Appropriately reducing the hydrogen peroxide feed rate or lowering the heating temperature of the bottom of the column will lower the temperature of the catalyst packing section, and vice versa. As shown in Figure 6, the reaction system pressure is controlled at 0.1-0.2 atm. When the pressure is higher than 0.2 atm, the addition rate of liquid ammonia in distillation column 1 is reduced or stopped, while hydrogen peroxide continues to be added. As hydrogen peroxide is added, the low-boiling-point ammonia is oxidized to the high-boiling-point hydroxylamine, and the system pressure gradually decreases. When the pressure is lower than 0.1 atm, the feed rate of liquid ammonia in distillation column 1 is appropriately increased until the pressure rises and is maintained at 0.1-0.2 atm. As shown in Figure 7, if the online spectrometer 17 detects the presence of hydrogen peroxide in the bottom material, the hydrogen peroxide feed rate should be appropriately reduced, and the ammonia feed rate should be reduced accordingly based on the molar feed ratio, so that the hydrogen peroxide has sufficient residence time in the catalyst loading section to react completely. The online spectrometer 17 can also simultaneously detect the content of hydroxylamine, ammonia, hydrogen peroxide, nitrite ions, and nitrate ions in the bottom material online. The minimum detection limit for hydrogen peroxide content is 1 ppm.

[0086] In one specific embodiment, the preparation method of the hydroxylamine free base of the present invention is as follows: a high-silica glass continuous distillation apparatus is used, the reboiler is a 1-liter high-silica glass three-necked flask, which is immersed in a temperature-controlled oil bath. A distillation column 1 is installed at one opening of the three-necked flask, which consists of upper and lower high-silica glass distillation columns. A high-silica glass distillation head is installed at the top of the column, and a high-silica glass condenser and reflux control device are configured (the liquid contact part is made of high-silica glass, polypropylene, or polytetrafluoroethylene plastic). A pressure gauge interface is set on the distillation head for installing a pressure gauge to monitor the system pressure. The upper distillation column is a catalyst-filled section 11, and a thermometer installation port is set in the middle of this section (for detecting the temperature of the middle section of the catalyst-filled section). It is filled with 200 ml of catalyst particles. The lower distillation column is filled with high-efficiency high-silica glass distillation packing 14, and the packing in the distillation column can provide at least 10 trays. A thermometer port and a hydrogen peroxide inlet are installed between the upper distillation column and the distillation head. A thermometer port and an ammonia inlet are installed between the upper and lower distillation columns. Each inlet is connected to an external hydraulic metering pump for hydrogen peroxide and liquid ammonia feeding, respectively. Before loading the catalyst, the distillation system is pre-treated with 20 wt.% analytical grade hydrochloric acid in a total reflux distillation process at least six times, each time requiring at least 2 hours of total reflux distillation (to remove sodium ions and other metal ions from the glass surface). It is then repeatedly rinsed with ultrapure water (conductivity less than 0.1 μS / cm) until the rinse water has a pH of 6-7 and a conductivity less than 0.3 μS / cm. The upper part of the catalyst loading section has a hydrogen peroxide inlet 12, where hydrogen peroxide of a certain concentration is introduced into the reaction system using a metering pump. The lower part of the catalyst loading section has an ammonia inlet 13, where liquid ammonia is introduced into the reaction system via a hydraulic metering pump. Before hydrogen peroxide is fed, a certain amount of liquid ammonia, ammonia water, water, or a mixture of water and organic solvent in a certain proportion is added to the reboiler and heated to total reflux for 1 hour. Then, hydrogen peroxide and ammonia are fed. At the beginning of the reaction, liquid ammonia first passes through a heat exchanger heated by hot water at approximately 70°C, and then enters the reaction system in gaseous form. When the reaction starts, and the temperature of the catalyst loading section 11 gradually rises above 60°C, the liquid ammonia will no longer pass through the heat exchanger, but will be directly introduced into the reaction system via a hydraulic pump until the reaction is complete. The entire reaction process is kept under total reflux. By adjusting the hydrogen peroxide feed rate, the liquid ammonia feed rate, and the oil bath temperature of the three-necked flask in the reboiler, the temperature of the middle section of the catalyst loading section can be controlled between 40-100°C, and further between 50-70°C. Appropriately reducing the hydrogen peroxide feed rate or lowering the oil bath temperature will lower the temperature of the catalyst loading section, and vice versa. The reaction system pressure is controlled at 0.1-0.2 atm. When the pressure is higher than 0.2 atm, the addition of liquid ammonia is stopped, while hydrogen peroxide continues to be added. As hydrogen peroxide is added, the low-boiling-point ammonia is oxidized into high-boiling-point hydroxylamine, and the system pressure will gradually drop. When the pressure is lower than 0.1 atm, the ammonia feed rate is appropriately increased until the pressure rises and is maintained at 0.1-0.2 atm.If hydrogen peroxide is detected in the bottom feed, the hydrogen peroxide feed rate and the ammonia feed rate should be appropriately reduced according to the molar feed ratio to allow sufficient residence time for the hydrogen peroxide in the catalyst loading section for complete reaction. The three-necked flask in the bottom column is equipped with an online spectrometer from H2OK Innovations, Inc., which can simultaneously detect the content of hydroxylamine, ammonia, hydrogen peroxide, nitrite ions, and nitrate ions in aqueous solutions or mixtures of water and organic solvents. The H2OK Innovations online spectrometer can detect hydrogen peroxide content down to a minimum limit of 1 ppm. Additionally, a thermometer is installed in the three-necked flask to monitor the bottom column temperature.

[0087] The hydroxylamine content in the bottom material of the tower can also be detected by HPLC, potentiometric titration and refractive index, while the nitrite, nitrate and chloride ion content can be detected by anion chromatography (the lowest chloride ion content that anion chromatography can accurately detect is, for example, 150 ppb), the ammonia content can also be detected by cation chromatography, and the metal ion content is detected by ICP-MS.

[0088] In another specific embodiment, the preparation method of the hydroxylamine free base of the present invention is as follows: a 1L high-silica glass round-bottom three-necked flask is assembled with a high-silica glass distillation apparatus as required, and a thermometer and an online spectral sensor from H2OK Innovations, Inc. of the United States are respectively installed on the round-bottom three-necked flask. After installation and hydrochloric acid pretreatment as required, add a certain amount of ultrapure water (the amount can be increased or decreased according to the actual situation, conductivity ≤0.1μs / cm) or a mixture of ultrapure water and organic solvent in a certain proportion, 0.1g of hydroxylamine stabilizer-cyclohexanediaminotetraacetic acid (CDTA), and 10ml of liquid ammonia. Heat to boiling and boil under total reflux for 30 minutes. Then, according to the hydrogen peroxide / ammonia molar ratio of 1.0:1.05, introduce hydrogen peroxide and liquid ammonia feed into the distillation column from the hydrogen peroxide inlet and ammonia inlet respectively using hydraulic metering pumps. The hydrogen peroxide can be commercially available in concentrations of 27.5wt.%, 35wt.%, and 50wt.%. Before the liquid ammonia is introduced into the distillation column by a hydraulic pump at the start of the reaction, it needs to be heated to complete vaporization by a heat exchanger. After the reaction starts, once the temperature in the middle section of the catalyst loading section rises above 60°C, the liquid ammonia is fed directly without passing through the heat exchanger.

[0089] The initial ammonia addition, catalyst loading, and feed rate can all be adjusted as needed.

[0090] After the hydrogen peroxide feed is stopped, the reaction ends. The reflux ratio at the top of the column is adjusted from total reflux to a reflux ratio of 1:1. Excess ammonia and water in the system are distilled off under reduced pressure (oil bath temperature controlled below 80℃) until the online spectrometer shows a hydroxylamine concentration of 55 wt.%, at which point there is no significant ammonia present in the bottom product. The bottom product after ammonia removal is an aqueous HAFB solution. The ammonia water distilled off can be used as pre-added ammonia water for the next reaction, or it can be concentrated and returned to the reaction system as feedstock ammonia.

[0091] Of course, the preparation of the hydroxylamine free base of the present invention can be carried out either by the batch method described above or by the continuous method. When the hydroxylamine free base is prepared by the continuous method, the material in the distillation vessel can be transferred to another distillation unit for concentration.

[0092] The technical solution of the present invention will be further described below through specific embodiments.

[0093] Example 1

[0094] Powdered TS-1 molecular sieve (purchased from the School of Chemical Engineering, Zhengzhou University) was prepared into spheres with a diameter of approximately 1 mm using a spherical rolling method (spraying with an aqueous solution containing 10 wt% citric acid and 5 wt% boehmite). These spheres were then calcined for 4 hours (480℃) to obtain spherical TS-1 molecular sieve catalysts. Alternatively, the catalysts could be tableted and then calcined to produce columnar catalysts with a diameter of 5 mm and a height of 10 mm, which were then crushed and sieved into catalyst particles of 20-30 mesh size. 200 ml of the above catalyst was loaded into distillation column 1, and the reaction was carried out as described above. The reboiler temperature was initially controlled at 105℃. As the reaction proceeded, the hydroxylamine concentration in the reboiler gradually increased, and the boiling point of the material in the reboiler also increased. Therefore, as the reaction progressed, the reboiler temperature was gradually increased to 113℃ and maintained until the reaction was completed. By adjusting the feed rates of hydrogen peroxide and liquid ammonia, as well as the reboiler oil bath temperature, the temperature in the middle section of the catalyst loading section was maintained at 50-65℃, while the system pressure was maintained at 0.1-0.2 atm.

[0095] Continuous feed rate under steady-state conditions:

[0096] 34.9 wt.% hydrogen peroxide feed rate: approximately 1.0 ml / min;

[0097] Liquid ammonia feed rate: approximately 0.26 ml / min.

[0098] Hydrogen peroxide and liquid ammonia are fed in this volume ratio. Depending on the reaction conditions, the hydrogen peroxide feed rate can be appropriately decreased or increased, and the liquid ammonia feed rate will also be adjusted accordingly. Based on the pressure of the reactive distillation system, the ammonia feed rate can be adjusted to maintain the system pressure between 0.1 and 0.2 atm.

[0099] During the continuous feed reaction, the crude product was continuously drawn from the bottom of the reactor to maintain the bottom liquid level at approximately 400-600 ml. A total of 2101 g of crude product was collected (specific gravity 1.05 g / ml, 2001 ml). The hydroxylamine concentration was determined to be 26.5 wt.%. Excess ammonia and water were distilled off in three batches under reduced pressure until the online detector showed that the hydroxylamine content in the bottom material was close to 55 wt.%. After cooling, the three batches of 55 wt.% HAFB crude product were mixed, sampled, tested, and weighed, yielding a total of 1086 g of crude product (specific gravity 1.12 g / ml, 961 ml) of 54.7 wt.% HAFB aqueous solution.

[0100] The analysis results of the crude product are as follows:

[0101] The crude product contained 54.7 wt.% hydroxylamine; 103 ppb ammonia; 156 ppb sodium; 81 ppb potassium; 37 ppb titanium; 36 ppb calcium; 25 ppb magnesium; 164 ppb aluminum; and extremely low levels of other metal ions, all less than 2 ppb. It also contained 255 ppb nitrite, 371 ppb nitrate, <150 ppb chloride, and 49 ppb silicate (ICP-MS detection). Hydrogen peroxide was not detected.

[0102] As shown above, the crude product contains very low levels of nitrite and nitrate ions, indicating that the process of this invention can effectively avoid the side reaction of hydrogen peroxide oxidizing hydroxylamine.

[0103] Besides titanium and aluminum ions, other metal ion impurities and chloride ion impurities in the crude product mainly come from hydrogen peroxide raw materials and catalysts. If higher purity electronic-grade hydrogen peroxide is used as raw material and a catalyst prepared with higher purity catalyst raw materials, the metal ion content and chloride ion content in the crude HAFB product will be lower.

[0104] The crude product contained very low levels of titanium ions, aluminum ions, and silicate ions, indicating that the catalyst was essentially not corroded by hydroxylamine and ammonia.

[0105] The total feed volume of 34.9 wt.% hydrogen peroxide was 1440 ml, and the weight was 1627 g (the specific gravity of 35 wt.% hydrogen peroxide was 1.13 g / ml). A total of 1086 g of 54.7 wt.% HAFB aqueous solution was obtained (specific gravity 1.12 g / ml). Based on hydrogen peroxide, the hydroxylamine yield was 96.2%.

[0106] Example 2

[0107] 200 ml of the TS-1 catalyst from Example 1 was loaded into a distillation column, and the reaction was carried out according to the method of Example 1. The difference from Example 1 was that 100 ml of ethanol and 50 ml of ultrapure water (conductivity ≤0.1 μs / cm) were added to the bottom of the column before the reaction, and the initial oil bath temperature was controlled at 90-95°C (based on the boiling of the solution in the bottom of the column). Other conditions were the same as in Example 1.

[0108] After stopping the feed, as in Example 1, water, ethanol and ammonia were removed by batch vacuum distillation until the hydroxylamine content in the bottom product was 55% or slightly lower.

[0109] The analysis results of the crude product are as follows:

[0110] The crude product contained 54.7 wt.% hydroxylamine; 126 ppb ammonia; 133 ppb sodium; 69 ppb potassium; 24 ppb titanium; 40 ppb calcium; 19 ppb magnesium; 138 ppb aluminum; and extremely low levels of other metal ions, all less than 2 ppb. It also contained 175 ppb nitrite, 334 ppb nitrate, <150 ppb chloride, and 37 ppb silicate (ICP-MS detection). Hydrogen peroxide was not detected.

[0111] Similar to the results obtained in Example 1 using pure water as a solvent, the addition of a certain amount of ethanol to the solvent resulted in very low levels of impurities such as nitrite and nitrate ions in the crude product, indicating that the process of this invention can effectively avoid the side reaction of hydrogen peroxide oxidation of hydroxylamine. Besides titanium and aluminum ions, other metal ion impurities in the crude product mainly originate from the hydrogen peroxide raw material and the catalyst. If higher purity electronic-grade hydrogen peroxide and a catalyst prepared from higher purity catalyst raw materials are used, the metal ion and chloride ion contents in the obtained HAFB crude product will be even lower.

[0112] The crude product contained very low levels of titanium ions, aluminum ions, and silicate ions, indicating that the catalyst was essentially not corroded by hydroxylamine and ammonia.

[0113] The total feed amount of 34.9 wt.% hydrogen peroxide was 1130 ml, and the weight was 1277 g (the specific gravity of 35 wt.% hydrogen peroxide was 1.13 g / ml). A total of 763.6 g of 54.1 wt.% HAFB aqueous solution (specific gravity 1.12 g / ml) was obtained. Based on hydrogen peroxide, the hydroxylamine yield was 95.5%.

[0114] Example 3

[0115] Powdered Fe-β-80 molecular sieve was prepared according to the method disclosed in "A High-Performance Composite Oxide Catalyst for Phenol Hydroxylation" (Zhang Xinfang et al., Fine Chemicals, 2005, 22(5): 369-372). Then, 400 g of Fe-β-80 molecular sieve, 80 g of pseudo-hydroalumina prepared by the carbonation method (containing 72 wt.% alumina), 8 g of starch, 14 ml of 65 wt.% nitric acid, and a certain amount of water were added to a kneader. After kneading for 1-2 hours, the mixture was extruded in an extruder and air-dried at room temperature for 24 hours. Then, it was calcined at 500°C for 4 hours, crushed, and sieved to obtain 20-30 mesh catalyst particles. 200 ml of the above catalyst was loaded into a distillation column, and the reaction was carried out under conditions similar to Example 1. The temperature of the catalyst loading section was maintained at 50-80°C by adjusting the feed rates of hydrogen peroxide and liquid ammonia, as well as the oil bath temperature of the column bottom.

[0116] Feeding speed:

[0117] 34.9 wt.% hydrogen peroxide feed rate: approximately 2.0 ml / min;

[0118] Liquid ammonia feed rate: approximately 0.52 ml / min.

[0119] Hydrogen peroxide and liquid ammonia are fed in this volume ratio. Depending on the reaction temperature, the hydrogen peroxide feed rate can be appropriately reduced or increased, and the liquid ammonia feed rate will also change accordingly. The ammonia feed rate can be adjusted according to the pressure of the reactive distillation system.

[0120] After the reaction was completed, the total feed volume of 34.9 wt.% hydrogen peroxide was 600 ml. The crude product with a low hydroxylamine concentration was distilled off in two batches under reduced pressure to remove excess ammonia and water until the online spectral sensor showed that the hydroxylamine content in the bottom product was close to 55 wt.%.

[0121] The analysis results of the crude product are as follows:

[0122] The hydroxylamine content in the bottom material of the tower was 53.9 wt.%; ammonia content: 86 ppb; sodium ion content: 307 ppb; potassium ion content: 81 ppb; iron ion content: 73 ppb; aluminum ion content: 256 ppb; calcium ion content: 94 ppb; magnesium ion content: 66 ppb; the contents of other metal ions were extremely low, all less than 2 ppb; nitrite ion content: 402 ppb; nitrate ion content: 871 ppb; chloride ion content: <150 ppb; silicate ion content: 33 ppb (ICP-MS detection); hydrogen peroxide could not be detected.

[0123] The crude product contained slightly higher levels of metal ion impurities such as sodium, potassium, calcium, and magnesium compared to Example 1. These impurities mainly originated from the catalyst. The low levels of iron, silicate, and aluminum ions indicate that the catalyst exhibits good resistance to hydroxylamine and ammonia corrosion.

[0124] The total feed volume of 34.9 wt.% hydrogen peroxide was 600 ml, and the weight was 678 g (the specific gravity of 35 wt.% hydrogen peroxide was 1.13 g / ml). A total of 433.6 g of 54.1 wt.% free hydroxylamine alkaline aqueous solution (specific gravity 1.12 g / ml) was obtained. Based on hydrogen peroxide, the hydroxylamine yield was 91.1%.

[0125] As can be seen from the above embodiments, the catalytic reactive distillation method uses a catalyst that catalyzes the oxidation of hydrogen peroxide and is insoluble in water and hydroxylamine. Ammonia and hydrogen peroxide are used as raw materials, and the reaction solvent can be water or a mixture of water and a low-boiling-point water-soluble organic solvent in a certain proportion. The crude HAFB aqueous solution obtained from the reaction has very low content of nitrite and nitrate ions as byproducts. This means that the preparation process disclosed in this invention can effectively avoid the side reaction of hydrogen peroxide oxidation of hydroxylamine and the decomposition reaction of hydroxylamine caused by metal elements in the catalyst. The hydroxylamine yield is high, and since no metal ion compounds are added during the synthesis process, the metal ion content in the crude product is also very low. For example, when the catalyst is a hierarchical porous TS-1 molecular sieve, the hydroxylamine yield can reach 96 wt.%. After removing excess ammonia and water by vacuum distillation, a 54.7 wt.% HAFB aqueous solution with a total metal ion impurity content of less than 1 ppm is obtained. If a catalyst prepared using higher purity electronic-grade hydrogen peroxide and catalyst raw materials with lower alkali metal and alkaline earth metal ion content is used, the metal ion content in the crude HAFB product will be further reduced. If a hydroxylamine free base with even lower impurity content is required, the above product can be treated using conventional ion exchange resin to remove metal ion impurities, resulting in electronic-grade HAFB with even lower metal ion content. This eliminates the need for frequent regeneration of the ion exchange resin, and the wastewater generated during resin regeneration is controllable. Alternatively, conventional vacuum distillation desalination can be used to further remove metal and non-metal ion impurities from the product. Since the total metal ion content of the HAFB raw material is less than 1 ppm, the bottom temperature of the distillation column will be significantly lower than the existing distillation desalination process temperature (the boiling point of the inorganic salt saturated aqueous solution of HAFB is much higher than that of the salt-free HAFB aqueous solution). Furthermore, there will be no solid inorganic salts in the distillation column bottom material after concentration. This avoids the problem of solid inorganic salts hindering mass and heat transfer within the column, thus preventing localized overconcentration and overheating of the bottom material and fundamentally eliminating the risk of explosion caused by excessive concentration and overheating of hydroxylamine.

[0126] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

[0127] Industrial application

[0128] The HAFB preparation process disclosed in this invention uses hydrogen peroxide and ammonia as raw materials. The entire process is simple, the hydroxylamine yield is high, the production cost is significantly lower than that of existing preparation processes, the safety performance is reliable, and there is almost no generation of "three wastes". The reaction process essentially solves the serious safety hazards and environmental problems of existing HAFB preparation processes, and it is easy to achieve continuous synthesis.

Claims

1. A reaction system for preparing a hydroxylamine free base, characterized in that, include: A distillation column, wherein a catalyst loading section is provided inside the distillation column, a hydrogen peroxide inlet is provided on the side wall of the distillation column above the catalyst loading section, and an ammonia inlet is provided on the side wall of the distillation column below the catalyst loading section. A heating device for heating the reboiler of the distillation column; A condenser, connected to the top of the distillation column, is used to condense the vapor flowing out from the top of the distillation column and to control the reflux ratio of the distillation column.

2. The reaction system for preparing hydroxylamine free base according to claim 1, characterized in that, The ammonia inlet is filled with distillation packing or a tray is provided between it and the bottom of the column, with the number of trays being greater than or equal to 5.

3. The reaction system for preparing a hydroxylamine free base according to claim 1, characterized in that, The distillation column is equipped with a pressure monitoring device at the top to monitor the pressure inside the distillation column; the catalyst loading section is equipped with a temperature monitoring device to monitor the temperature of the catalyst loading section; the reboiler is equipped with an online spectral sensor to monitor the hydrogen peroxide content in the reboiler liquid; and / or, the catalyst loaded in the catalyst loading section is a catalyst that can catalyze the oxidation reaction of hydrogen peroxide.

4. The reaction system for preparing a hydroxylamine free base according to claim 3, characterized in that, It also includes a control device connected to the pressure monitoring device at the top of the distillation column, the temperature monitoring device in the catalyst packing section, the online spectral sensor in the bottom of the column, and the condensation device, so as to monitor and adjust the pressure at the top of the distillation column, the temperature in the catalyst packing section, the hydrogen peroxide content in the bottom liquid, and the reflux ratio in real time.

5. A reaction apparatus for preparing hydroxylamine free base, characterized in that, include: A distillation column, wherein a catalyst loading section is provided inside the distillation column, a hydrogen peroxide inlet is provided on the side wall of the distillation column above the catalyst loading section, and an ammonia inlet is provided on the side wall of the distillation column below the catalyst loading section. A heating device for heating the reboiler of the distillation column; A condenser, connected to the top of the distillation column, is used to condense the vapor flowing out from the top of the distillation column; The control device is connected to the pressure monitoring device at the top of the distillation column, the temperature monitoring device in the catalyst packing section, and the online spectral sensor in the bottom of the column to monitor and adjust the pressure at the top of the distillation column, the temperature in the catalyst packing section, and the hydrogen peroxide content in the liquid in the bottom of the column in real time.

6. The reaction apparatus for preparing hydroxylamine free base according to claim 5, characterized in that, The ammonia inlet is filled with distillation packing or a tray is provided between it and the bottom of the column, with the number of trays being greater than or equal to 5.

7. The reaction apparatus for preparing hydroxylamine free base according to claim 5, characterized in that, The pressure monitoring device installed at the top of the distillation column is used to monitor the pressure inside the distillation column; the temperature monitoring device installed in the catalyst loading section is used to monitor the temperature of the catalyst loading section; the online spectral sensor installed in the bottom of the column is used to monitor the hydrogen peroxide content in the bottom liquid; and / or, the catalyst loaded in the catalyst loading section is a catalyst that can catalyze the oxidation reaction of hydrogen peroxide.

8. A method for preparing hydroxylamine free base, characterized in that, Includes the following steps: Step 1: A catalyst is loaded into a distillation column, ammonia is introduced below the catalyst, and hydrogen peroxide is introduced above the catalyst. The temperature at the catalyst is controlled at 40-100℃, and the pressure inside the distillation column is 0.1-0.2 atm. The ammonia and hydrogen peroxide react under the action of the catalyst to generate hydroxylamine free base. Step 2: The hydroxylamine free base flows downward into the bottom of the distillation column and is continuously enriched; The catalyst is a catalyst that catalyzes the oxidation reaction of hydrogen peroxide.

9. The method for preparing hydroxylamine free base according to claim 8, characterized in that, The catalyst is a titanium silicate molecular sieve or an iron-based oxide catalyst modified with Hβ-80 zeolite.

10. The method for preparing hydroxylamine free base according to claim 8, characterized in that, The hydrogen peroxide is calculated as hydrogen peroxide, and the feed molar ratio of hydrogen peroxide to ammonia is 1.0:1.0-1.2; the hydrogen peroxide also includes an organic solvent, and the ammonia also includes water and / or an organic solvent, wherein the organic solvent is at least one selected from methanol, ethanol, n-propanol, isopropanol, tert-butanol, n-butanol, and isobutanol.

11. The method for preparing hydroxylamine free base according to claim 8, characterized in that, The temperature of the bottom of the distillation column is 40-120℃. The ammonia in the bottom is heated and rises. The vapor at the top of the distillation column condenses into liquid and returns to the distillation column to participate in the reaction again at the catalyst.

12. The method for preparing hydroxylamine free base according to claim 8, characterized in that, It also includes drawing out the crude reaction product containing hydroxylamine from the bottom of the distillation column, removing ammonia and some water from the crude reaction product, and obtaining hydroxylamine free base.

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