A catalytic oxidation catalyst and a preparation method thereof, and a method for removing organic matters in hydrochloric acid by catalytic oxidation

Abstract

The application discloses a catalytic oxidation catalyst and a preparation method thereof, and a method for removing organic matters in hydrochloric acid through catalytic oxidation. x Pr y P 3-7 wt%, carrier 93-97 wt%, wherein M is a transition metal, including one or more of nickel, iron, cobalt and molybdenum; Pr is a rare earth element praseodymium; wherein the carrier includes silicon dioxide and / or activated carbon. The organic matters in the hydrochloric acid are removed through the catalytic oxidation mode, the TOC of the hydrochloric acid is reduced, the quality of the hydrochloric acid is optimized, and the downstream application market is widened. The application has remarkable economic benefits and social benefits.

Description

Technical Field

[0001] This invention relates to the field of hydrochloric acid purification, and more specifically to a method for removing organic matter from hydrochloric acid. Background Technology

[0002] Hydrochloric acid is an aqueous solution of hydrogen chloride, possessing a strong, pungent odor and high corrosiveness. It is widely used in downstream industries such as metallurgy, leather processing, and steel processing. Downstream applications of hydrochloric acid have specific requirements regarding its concentration, total organic carbon (TOC), and metal ion content. Excessively high TOC levels can adversely affect ion-exchange membrane electrolyzers in downstream brine electrolysis, leading to risks such as increased membrane voltage and low current efficiency, which are detrimental to production. Therefore, it is essential to strictly control the TOC content in hydrochloric acid products.

[0003] When the process fluctuates or malfunctions, the quality of the by-product hydrochloric acid declines, the total organic matter (TOC) in the hydrochloric acid exceeds the standard, and occasionally, metal ion levels exceed the standard, affecting the quality and sales conditions of the hydrochloric acid. This may lead to hydrochloric acid overstocking, causing a reduction in production load and impacting production efficiency. Therefore, this patented invention adds a hydrochloric acid treatment process, using oxidation to remove organic impurities from the hydrochloric acid.

[0004] CN218403680U discloses an apparatus for removing organic matter from hydrochloric acid, a byproduct of methylbenzyl chloride production. This apparatus uses a separation tank and a resin column to adsorb and remove organic matter from the hydrochloric acid. The resin can be reused through regeneration. Resin adsorption is more effective for removing high concentrations of organic matter, but its effect is limited for low concentrations.

[0005] CN115340069A discloses a hydrochloric acid recovery and treatment technology for a byproduct of a chlor-alkali fine chemical process. The technology involves passing hydrogen chloride waste gas containing organic matter into an incinerator. After combustion, the resulting tail gas is further absorbed by quenching water to obtain hydrochloric acid, which can convert most of the hydrocarbon organic matter in the tail gas into carbon dioxide and water. However, the incineration process of hydrogen chloride waste gas is prone to corrosion of the incinerator, requires significant equipment investment, and is only effective against hydrocarbon organic matter, thus limiting its application.

[0006] CN105618079A discloses a non-precious metal catalytic oxidation composite material, which uses pecan powder as a base, with iron oxide, copper, and manganese dioxide supported on the matrix to form a composite mesoporous material. This material can catalytically oxidize laboratory organic wastewater and reduce COD. However, this catalyst uses metal oxides as the main catalytic component, which are easily lost under acidic conditions, limiting the application of this method. Summary of the Invention

[0007] The purpose of this invention is to provide a catalytic oxidation catalyst and its preparation method, and a method for catalytic oxidation to remove organic matter from hydrochloric acid, thereby reducing the TOC in hydrochloric acid to below 15 ppm.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A catalytic oxidation catalyst comprising the following components:

[0010] M x Pr y P 3-7wt%,

[0011] Carrier 93-97 wt%,

[0012] Where M is a transition metal, including but not limited to one or more of nickel, iron, cobalt, and molybdenum; Pr is the rare earth element praseodymium; and the support includes but is not limited to porous media such as silica and activated carbon, which can be effectively applied to hydrochloric acid systems.

[0013] The method for preparing the catalyst according to the present invention includes the following steps:

[0014] a. Weigh the transition metal salt and prepare a solution, add praseodymium salt in a certain proportion, add a carrier to the solution for impregnation, age, evaporate and dry to obtain the intermediate product loaded with transition metal salt;

[0015] b. The obtained intermediate product is vacuum dried and placed in a tube furnace for high-temperature phosphating under an inert atmosphere to obtain a phosphide;

[0016] c. Mix the phosphate obtained in step b with the melamine solution in a certain proportion, disperse it evenly by ultrasonication, and then evaporate and dry it.

[0017] d. The obtained dried intermediate product is calcined at high temperature under an inert atmosphere to obtain nitrogen-doped bimetallic phosphide catalyst M. x Pr y P.

[0018] In step a of this invention, the mass ratio of the carrier to the transition metal salt is 8:1 to 10:1.

[0019] In step a of this invention, the mass ratio of the carrier to the praseodymium salt is 100:1 to 100:5.

[0020] In step a of this invention, the aging temperature range is 40-80℃, preferably 50-60℃.

[0021] In step b of this invention, the phosphorus source for high-temperature phosphating includes, but is not limited to, one or more of red phosphorus, sodium hypophosphite, and sodium dihydrogen phosphate.

[0022] In step b of this invention, the phosphating time is 2-4 hours.

[0023] In step b of this invention, the phosphating temperature range is 400-800℃, preferably 500-600℃.

[0024] In step c of this invention, the mass ratio of melamine to phosphate is 1:1 to 3:1, and after being ultrasonically dispersed evenly, it is evaporated and dried, preferably by vacuum drying.

[0025] In step d of this invention, the inert atmosphere gas is one or more of nitrogen, argon, and carbon dioxide.

[0026] In step d of this invention, the high-temperature calcination temperature is 500-700℃, and the calcination time is 1-2h.

[0027] In step d of this invention, the purpose of high-temperature calcination is to solidify the nitrogen-doped matrix and improve the interfacial catalytic ability between the main catalyst particles.

[0028] A method for catalytic oxidation to remove organic matter from hydrochloric acid includes the following steps:

[0029] High-TOC hydrochloric acid is fed into a packed tower loaded with a catalyst. Hydrochloric acid is introduced at the top of the tower, and air, preferably ozone, is introduced at the bottom. The TOC in the hydrochloric acid is oxidized and removed by controlling an appropriate temperature. The oxidation product is mainly CO2. The oxidized hydrochloric acid obtained at the bottom of the tower has a TOC of <15ppm, preferably <10ppm.

[0030] The high-TOC hydrochloric acid described in this invention has a TOC higher than 15 ppm and contains formic acid, acetic acid, straight-chain amines, and possibly organic compounds such as chlorobenzene, aniline, and phenol.

[0031] Nitrogen-doped bimetallic phosphide catalysts exhibit strong catalytic activity in acidic systems. Rare earth metals and transition metals can activate organic substrates and oxidants respectively, effectively lowering the energy barrier of the reaction transition state and forming a synergistic effect. The nitrogen-doped supported catalyst exhibits excellent interfacial catalytic performance, improving the oxidation mass transfer process. It can catalytically oxidize and remove low-content organic matter from hydrochloric acid, including formic acid, acetic acid, and small molecule amines, controlling the TOC of hydrochloric acid to less than 15 ppm, meeting the requirements of downstream manufacturers.

[0032] During the catalytic oxidation process, the catalytic space velocity is controlled between 0.5 and 2 h⁻¹. -1 The catalytic temperature is 50-80℃. The volume ratio of oxidant gas to feed hydrochloric acid is 1:1 to 10:1.

[0033] The beneficial effects of this invention are as follows:

[0034] (1) After using this process, the TOC content of the by-product hydrochloric acid is less than 15ppm, which makes it more widely applicable and expands the downstream market.

[0035] (2) The oxidant used in this process is oxygen or ozone, and the main product of catalytic oxidation decomposition is CO2, which is green and environmentally friendly. Detailed Implementation

[0036] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments and should also include any other known modifications within the scope of the claims of the present invention.

[0037] Example 1 Preparation of Catalyst A

[0038] 5g of ferric nitrate was weighed and prepared into a 5% ferric nitrate solution. 1g of praseodymium chloride and 45g of activated carbon support were added to the solution, and the solution was heated in a water bath at 50℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was placed in a tube furnace and phosphated at 500℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. After cooling, 20g of the phosphate was mixed with 30g of melamine solution, sonicated at room temperature for 1 hour, evaporated, and dried. The dried product was then placed in a tube furnace and calcined at 500℃ for 2 hours under a nitrogen atmosphere to obtain catalyst A.

[0039] Example 2 Preparation of Catalyst B

[0040] 12g of cobalt chloride was weighed and prepared into a 5% cobalt chloride solution. 3g of praseodymium chloride and 100g of activated carbon support were added to the solution, and the solution was heated in a water bath at 70℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was placed in a tube furnace and phosphated at 600℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. After cooling, 50g of the phosphate was mixed with 80g of melamine solution, sonicated at room temperature for 1 hour, evaporated, and dried. The dried product was then placed in a tube furnace and calcined at 600℃ for 2 hours under a nitrogen atmosphere to obtain catalyst B.

[0041] Example 3 Preparation of Catalyst C

[0042] 11g of nickel chloride was weighed and a 5% nickel chloride solution was prepared. 4g of praseodymium chloride and 100g of activated carbon support were added to the solution, and the solution was heated in a water bath at 60℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was placed in a tube furnace and phosphated at 600℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. After cooling, 50g of the phosphate was mixed with 100g of melamine solution, sonicated at room temperature for 1 hour, evaporated, and dried. The dried product was then placed in a tube furnace and calcined at 600℃ for 2 hours under a nitrogen atmosphere to obtain catalyst C.

[0043] Comparative Example 1: Preparation of Catalyst D

[0044] 2g of praseodymium chloride was weighed and prepared into a 2% praseodymium chloride solution. 100g of activated carbon support was added to the solution, and the solution was heated in a water bath at 50℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was placed in a tube furnace and phosphated at 500℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. After cooling, 20g of the phosphate was mixed with 30g of melamine solution, sonicated at room temperature for 1 hour, evaporated, and dried. The dried product was then placed in a tube furnace and calcined at 500℃ for 2 hours under a nitrogen atmosphere to obtain catalyst D.

[0045] Comparative Example 2: Preparation of Catalyst E

[0046] 12g of nickel chloride was weighed and prepared into a 5% nickel chloride solution. 100g of activated carbon support was added to the solution, and the solution was heated in a water bath at 50℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was placed in a tube furnace and phosphated at 500℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. After cooling, 20g of the phosphate was mixed with 30g of melamine solution, sonicated at room temperature for 1 hour, evaporated, and dried. The dried product was then placed in a tube furnace and calcined at 500℃ for 2 hours under a nitrogen atmosphere to obtain catalyst E.

[0047] Comparative Example 3: Preparation of Catalyst F

[0048] 12g of cobalt chloride was weighed and prepared into a 5% cobalt chloride solution. 3g of praseodymium chloride and 100g of activated carbon support were added to the solution, and the solution was heated in a water bath at 70℃ for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain a catalyst intermediate. This intermediate was then placed in a tube furnace and phosphating at 500℃ for 3 hours under a nitrogen atmosphere using sodium dihydrogen phosphate as the phosphorus source. The dried product was then placed in a tube furnace and calcined at 600℃ for 2 hours under a nitrogen atmosphere to obtain catalyst F.

[0049] Comparative Example 4: Preparation of Catalyst G

[0050] 12g of cobalt chloride was weighed to prepare a 5% cobalt chloride solution. 3g of praseodymium chloride and 100g of activated carbon support were added to the solution, and the mixture was kept at 70℃ in a water bath for 1 hour. Subsequently, the solution was evaporated under reduced pressure to obtain the catalyst intermediate. 50g of the impregnated catalyst was mixed with 80g of melamine solution, sonicated at room temperature for 1 hour, evaporated to dryness, and the dried product was placed in a tube furnace for further high-temperature heating under a nitrogen atmosphere for calcination at 600℃ for 2 hours to obtain catalyst G.

[0051] Example 4: Hydrochloric acid treatment 1:

[0052] Hydrochloric acid with an initial concentration of 32% and a TOC of 30 ppm was introduced into a catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst A was loaded. The hydrochloric acid was dispersed via a distributor and discharged from the bottom of the reactor after catalysis by catalyst A. Ozone was introduced into the bottom of the reactor for oxidation, with a gas flow rate controlled at 200 m³ / h. 3 / h, the reactor temperature is maintained at 70℃ by electric heating; low-TOC hydrochloric acid is obtained from the reactor liquid phase outlet;

[0053] Example 5: Hydrochloric acid treatment 2

[0054] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into the catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst B was loaded. The hydrochloric acid was dispersed via a distributor and, after being catalyzed by catalyst B, was discharged from the bottom of the reactor. Ozone was introduced into the bottom of the catalyst reactor for oxidation, with the gas flow rate controlled at 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0055] Example 6 Hydrochloric acid treatment 3:

[0056] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into the catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 150 kg of catalyst C was loaded. The hydrochloric acid was dispersed via a distributor and, after catalysis by catalyst C, discharged from the bottom of the reactor. Ozone was introduced into the bottom of the catalyst reactor for oxidation, with a controlled gas flow rate of 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0057] Comparative Example 5: Hydrochloric acid treatment 4

[0058] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into a catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst D was loaded. The hydrochloric acid was dispersed via a distributor and, after being catalyzed by catalyst D, was discharged from the bottom of the reactor. Ozone was introduced into the bottom of the catalyst reactor for oxidation, with a controlled gas flow rate of 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0059] Comparative Example 6: Hydrochloric acid treatment 5

[0060] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into a catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst E was loaded. The hydrochloric acid was dispersed via a distributor and discharged from the bottom of the reactor after catalysis by catalyst E. Ozone was introduced into the bottom of the reactor for oxidation, with a controlled gas flow rate of 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0061] Comparative Example 7: Hydrochloric Acid Treatment 6

[0062] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into a catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst F was loaded. The hydrochloric acid was dispersed via a distributor and, after being catalyzed by catalyst F, was discharged from the bottom of the reactor. Ozone was introduced into the bottom of the catalyst reactor for oxidation, with a controlled gas flow rate of 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0063] Comparative Example 8: Hydrochloric acid treatment 7

[0064] Hydrochloric acid with an initial concentration of 32% and a TOC of 40 ppm was introduced into a catalytic oxidation reactor at a flow rate of 100 kg / h. Approximately 100 kg of catalyst G was loaded. The hydrochloric acid was dispersed via a distributor and, after catalysis by catalyst G, discharged from the bottom of the reactor. Ozone was introduced into the bottom of the catalyst reactor for oxidation, with a gas flow rate controlled at 500 m³ / h. 3 The reactor temperature is maintained at 70°C per hour by electric heating; low-TOC hydrochloric acid is obtained from the liquid phase outlet of the reactor.

[0065] The results of the examples and comparative examples are shown in Table 1.

[0066] Table 1 Results of Examples and Comparative Examples

[0067]

[0068]

[0069] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A catalytic oxidation catalyst, comprising the following components: MxPryP3-7wt%, Carrier 93-97 wt%, Wherein M is a transition metal, including one or more of nickel, iron, cobalt, and molybdenum; Pr is the rare earth element praseodymium; wherein the support includes silica and / or activated carbon, and the sum of the contents of MxPryP and the support is not 100%; The method for preparing the catalyst includes the following steps: a. Weigh the transition metal salt and prepare a solution, add praseodymium salt in a certain proportion, add a carrier to the solution for impregnation, age, evaporate and dry to obtain the intermediate product loaded with transition metal salt; b. The obtained intermediate product is vacuum dried and placed in a tube furnace for high-temperature phosphating under an inert atmosphere to obtain a phosphide; c. Mix the phosphate obtained in step b with the melamine solution in a certain proportion, disperse it evenly by ultrasonication, and then evaporate and dry it. d. The obtained dried intermediate product is calcined at high temperature under an inert atmosphere to obtain nitrogen-doped bimetallic phosphide catalyst.

2. The catalyst according to claim 1, characterized in that, In step a, the mass ratio of the carrier to the transition metal salt is 8:1 to 10:

1.

3. The catalyst according to claim 2, characterized in that, In step a, the mass ratio of the carrier to praseodymium salt is 100:1 to 100:

5.

4. The catalyst according to claim 2, characterized in that, In step a, the aging temperature range is 40-80℃.

5. The catalyst according to claim 2, characterized in that, In step a, the aging temperature range is 50-60℃.

6. The catalyst according to claim 2, characterized in that, In step b, the phosphorus source for the high-temperature phosphating includes one or more of red phosphorus, sodium hypophosphite, and sodium dihydrogen phosphate.

7. The catalyst according to claim 2, characterized in that, In step b, the phosphating time is 2-4 hours and the phosphating temperature is 400-800℃.

8. The catalyst according to claim 7, characterized in that, In step b, the phosphating temperature is 500-600℃.

9. The catalyst according to claim 2, characterized in that, In step c, the mass ratio of melamine to phosphate is 1:1 to 3:

1.

10. The catalyst according to claim 2, characterized in that, In step d, the high-temperature calcination temperature is 500-700℃, and the calcination time is 1-2 hours.

11. A method for catalytic oxidation to remove organic matter from hydrochloric acid, comprising the following steps: High-TOC hydrochloric acid is passed into a packed tower loaded with the catalyst according to any one of claims 1-10, wherein TOC ≥ 30 ppm. Hydrochloric acid is passed into the top of the tower, and air or ozone is passed into the bottom of the tower. The TOC in the hydrochloric acid is oxidized and removed by controlling an appropriate temperature. The oxidation product is mainly CO2. Oxidized hydrochloric acid with TOC < 15 ppm is obtained in the bottom of the tower.

12. The method according to claim 11, characterized in that, The TOC in the oxidized hydrochloric acid obtained from the column bottom is <10ppm.

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