Non-reducing synthetic gas decarbonyl iron protective agent and preparation method thereof

Abstract

This invention discloses a non-reducing syngas decarbonyl iron protective agent and its preparation method. The active centers of the protective agent are composed of CuO / Cu and ZnO / Zn, and the support of the protective agent is a high silica-to-alumina ratio molecular sieve, with the remainder being lubricants and forming agents. The components of the protective agent, by mass percentage, are: copper oxide content 0.01%–15.0%, zinc oxide content 0.01%–10.0%, molecular sieve content 75.0%–98.0%, lubricant content 0.1%–3%, and forming agent content 0.2%–1.0%. The decarbonyl iron protective agent prepared by this invention is a catalytic dissociation type with porous molecular sieve support adsorbed on copper-zinc active centers. It features high specific surface area, a wide active reaction temperature range, high total iron-nickel capacity, and high removal rate. The protective agent can fully remove carbonyl iron from the syngas, protecting the long-term stable operation of the subsequent methanol catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation technology, specifically relating to a non-reducing syngas decarbonylation iron protecting agent and its preparation method. Background Technology

[0002] Methanol, as an important basic chemical product, is widely used in chemical, pharmaceutical, and textile industries.

[0003] Common medium- and low-pressure methanol synthesis catalysts are copper-based catalysts. This type of catalyst is extremely sensitive to poisons. The known poisons are mainly: (1) sulfur and sulfur compounds; (2) chlorine and chlorine compounds; (3) trace amounts of ammonia; and (4) trace amounts of arsenic and arsenic compounds. With the trend of large-scale development of production plants, the carbonyl iron produced in the synthesis gas has become a problem that urgently needs to be solved, and its side effects are also extremely obvious and multifaceted.

[0004] The effects of carbonyl iron and carbonyl nickel on methanol synthesis are closely related to the conditions of the synthesis reaction. Although only carbon, hydrogen, and oxygen participate in the methanol synthesis reaction, the reaction conditions, such as temperature, pressure, space velocity, catalyst, and impurities in the reaction gas and vaporizing agent, can cause the reaction to deviate from the main direction, generating various by-products that become impurities in methanol. The presence of these impurities not only makes the distillation and extraction purification process more difficult but also affects the product quality. The presence of carbonyl iron and carbonyl nickel can cause many side reactions: (1) reactions that generate hydrocarbons; (2) reactions that generate paraffinic hydrocarbons; and (3) the effect on product purity.

[0005] Therefore, in order to ensure the long-term operation of the device, it is imperative to develop a protective agent related to decarbonylation of iron and nickel.

[0006] In theory, there are many methods for removing carbonyl iron and nickel, mainly divided into two categories: wet and dry methods. Wet methods include direct absorption and oxidation absorption, but these methods involve complex equipment, difficult operation, and the generation of wastewater, with used absorbents also being difficult to treat. Dry methods mainly include physical methods and catalytic removal methods. A common physical method is diatomaceous earth ball adsorption, but this method results in weak adsorption due to physical adsorption, leading to incomplete adsorption, and requiring replacement after saturation. Catalytic removal methods utilize the active metal adsorption of the adsorbent; a common catalytic removal method is decomposition.

[0007] Currently, based on actual operational observations at multiple methanol production plants, the performance of existing protective agents in the market is not meeting expectations. Various domestic and international models of protective agents exhibit only moderate iron-nickel removal activity, with low total carbonyl iron capacity and a tendency for breakthrough, leading to excessive iron-nickel content in the methanol catalyst. Furthermore, protective agents are categorized into two types: low-temperature physical adsorption and medium-temperature catalytic dissociation and deposition, resulting in relatively poor adaptability to feedstock gases. Summary of the Invention

[0008] Objective of this invention: To address the shortcomings of existing technologies, this invention provides a non-reducing syngas decarbonylation iron protecting agent and its preparation method. Using this protecting agent, the adsorption and catalytic decomposition of carbonyl iron can be achieved.

[0009] The protective agent prepared by this invention can remove carbonyl iron formed in the syngas during methanol production, thereby improving the iron removal capacity of the protective agent. Without affecting the main methanol process, it protects the activity and lifespan of the methanol synthesis catalyst in subsequent processes, better meeting the production requirements of long-term stable operation of industrial plants.

[0010] Technical solution: The objective of this invention is achieved through the following technical solution:

[0011] This invention provides a non-reducing decarbonylation iron protecting agent. The active centers of the protecting agent are composed of CuO / Cu and ZnO / Zn. The carrier of the protecting agent is a high silica-to-alumina ratio molecular sieve, and the remainder consists of lubricant and forming agent. The components of the protecting agent, by mass percentage, are: copper oxide content of 0.01%–15.0%, zinc oxide content of 0.01%–10.0%, molecular sieve content of 75.0%–98.0%, lubricant content of 0.1%–3%, and forming agent content of 0.2%–1.0%.

[0012] This invention utilizes the large specific surface area and numerous micropores of molecular sieve supports to fully physically adsorb carbonyl iron, which is then deposited after catalytic dissociation at copper-zinc active centers. The copper-zinc based protective agent exhibits good decarbonyl iron removal activity and high iron-nickel capacity, and its metal active centers include Cu and Zn. The support is composed of high silica-to-alumina ratio molecular sieves. The metal active centers in this system exist in the form of basic complex salts, uniformly distributed among the molecular sieve supports, and alternately and cyclically attached to the supports.

[0013] Preferably, the copper oxide content is 2% to 10%, and the zinc oxide content is 2.0% to 10.0%.

[0014] This invention also provides a method for preparing the above-mentioned decarbonylated iron protecting agent, comprising the following steps:

[0015] (1) The active matrix of the protective agent was obtained by co-precipitation of the matrix precipitant with a copper-zinc mixture;

[0016] (2) Using water glass solution, guiding agent solution, aluminum sulfate solution, sodium aluminate solution and silica-alumina gel solution as raw materials, a gelation reaction, aging and post-treatment are carried out to obtain a high silica-alumina ratio molecular sieve carrier.

[0017] (3) Mix the active matrix of the protective agent obtained in step (1) and the high silica-alumina ratio molecular sieve carrier obtained in step (2), pulverize, let stand, filter, dry and granulate, add lubricant and forming agent to obtain the protective agent.

[0018] Preferably, in step (1), the molar ratio of copper and zinc ions in the copper-zinc mixture is 1:2 to 2:1, and the molar concentration of the copper-zinc mixture is 0.1 mol / L to 5 mol / L.

[0019] Preferably, in step (1), the parent precipitant is a sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, or ammonia solution, with a molar concentration of 0.01 mol / L to 4.0 mol / L.

[0020] Preferably, in step (1), the temperature of the coprecipitation is 20-90°C, the pH value of the coprecipitation process is controlled at 6.5-8.0, and the final pH value of the coprecipitation is 7.0-7.5.

[0021] Further, in step (1), at a temperature of 20 to 90°C, a parent precipitant with a concentration of 0.1 mol / L to 3.0 mol / L is added to a Cu and Zn mixed nitrate solution to carry out a coprecipitation reaction. The pH value during the coprecipitation process is controlled at 6.5 to 8.0, and the final pH value is controlled at 7.0 to 7.5. After aging for 10 to 120 minutes, the active parent precipitant is obtained after washing with water.

[0022] In step (1) of this invention, the controlled preparation technical parameters include, but are not limited to, feeding rate, precipitation temperature, process pH value, and precipitation endpoint pH value. After precipitation, the solution is washed with deionized water, and the conductivity of the washing endpoint solution is controlled.

[0023] ≤10μs / cm.

[0024] Preferably, in step (2), the molar ratio of Na2O, Al2O3, and SiO2 in the gelation reaction is controlled to be 2-3.5:1:8-10.

[0025] Preferably, in step (2), the temperature of the gelation reaction is 30-80°C and the time is 20-80 min; the aging process conditions are: aging at 90-100°C for 16-40 h.

[0026] Preferably, in step (2), the preparation method of the guiding agent solution is as follows: mix sodium aluminate solution and sodium hydroxide solution, stir evenly, add water glass solution, and let stand at 15-40°C for 8-24 hours to obtain the solution.

[0027] Furthermore, the raw materials are added concurrently to the gelation reactor.

[0028] Preferably, in step (3), the settling time is 20-100 min.

[0029] Beneficial effects:

[0030] The carbonyl iron removal protective agent prepared by this invention possesses both physical adsorption and catalytic decomposition deposition reaction processes. The protective agent exhibits characteristics such as high adsorption capacity, good iron removal activity, and high carbonyl iron capacity, which can better protect the long-term operation of methanol synthesis catalysts. It is particularly suitable for use in large-scale medium- and low-pressure methanol synthesis plants, especially in common million-ton-level large-scale methanol industrial production plants. Attached Figure Description

[0031] Figure 1 This is a CO-TPD diagram of different decarbonylation iron protecting agents. Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0033] Example 1

[0034] (1) Add 300 mL of 0.1 mol / L sodium carbonate solution to 60 mL of 0.5 mol / L Cu and Zn (molar ratio of 1:2) mixed nitrate aqueous solution to carry out coprecipitation reaction. The coprecipitation temperature is 40℃. The parent precipitate is washed with deionized water. The pH value during the precipitation process is controlled at 6.5. The final pH value of the filtrate is 7.0. After aging at 40℃ for 60 min, the parent precipitate slurry is obtained, which is the active parent of the protective agent.

[0035] (2) Preparation of sodium aluminate solution for the production of high silica-to-alumina ratio molecular sieves: 500 ml of sodium hydroxide solution with a concentration of 31.8% and 223.8 g of aluminum hydroxide powder with an Al2O3 content of 62.7% were added to a stirred reactor. The reaction pressure was 0.2 MPa, the reaction temperature was 125℃, and the reaction time was 6 h. After filtration, sodium aluminate solution for the production of high silica-to-alumina ratio molecular sieves was prepared.

[0036] Filtered qualified material with SiO2 concentration of 45.8 g / L and Na2O concentration of 25.2 g / L was reacted with aluminum sulfate solution with Al2O3 concentration of 90.2 g / L. After filtration and washing, a silica-alumina gel solution was prepared. The mass data of the silica-alumina gel were: SiO2 61.9%, Al2O3 16.6%, Na2O 13.7%, solid content 11.9%, and density 1.096.

[0037] 135.6 ml of sodium aluminate solution with Al2O3 concentration of 150.5 g / L and Na2O concentration of 180.3 g / L, and 270.6 ml of sodium hydroxide solution with a concentration of 31% were added to a stirred reactor. After stirring evenly, 718.2 ml of water glass solution with SiO2 concentration of 250.6 g / L and modulus of 3.25 was added. The aging temperature was controlled at 28℃, and the mixture was allowed to stand for aging for 20 hours. After aging, 169 ml of chemical water was added. The resulting product is the directing agent solution.

[0038] 255.9 ml of the prepared silica-alumina gel solution, 294.2 ml of water glass solution with a SiO2 concentration of 250.6 g / L and a modulus of 3.25, 52.8 ml of sodium aluminate solution, 50 ml of directing agent solution, and 65.8 ml of aluminum sulfate solution with an Al2O3 concentration of 90.5 g / L were added concurrently to the gelation reactor. The gelation reaction was carried out at 40°C with stirring for 40 minutes. The temperature was then raised to 98°C, and the mixture was allowed to stand for 28 hours for aging. After washing and filtration, the high silica-alumina ratio molecular sieve support was obtained.

[0039] (3) Mix the above-mentioned parent precipitate slurry and the high silica-alumina ratio molecular sieve carrier, let stand for 20 minutes, filter, dry and granulate, add 1.2% graphite lubricant and 0.5% water, and press into tablets to make carbonyl iron protective agent sample C1.

[0040] Example 2

[0041] (1) Add 200 mL of 0.5 mol / L sodium bicarbonate solution to 100 mL of 1 mol / L Cu and Zn (molar ratio 1:1) mixed nitrate aqueous solution to carry out coprecipitation reaction. The coprecipitation temperature is 60℃. The parent precipitate is washed with deionized water. The pH value during the precipitation process is controlled at 7.0. The final pH value of the filtrate is 7.2. After aging at 60℃ for 100 min, the parent precipitate slurry is obtained, which is the active parent of the protective agent.

[0042] (2) Preparation of sodium aluminate solution for high silica-to-alumina ratio molecular sieve production: 500 ml of 31.8% sodium hydroxide solution and 218.61 g of aluminum hydroxide powder with Al2O3 content of 64.2% were added to a stirred reactor. The reaction pressure was 0.2 MPa, the reaction temperature was 125℃, and the reaction time was 6 h. After filtration, sodium aluminate solution for high silica-to-alumina ratio molecular sieve production was prepared.

[0043] Filtered, qualified material with a SiO2 concentration of 45.8 g / L and a Na2O concentration of 25.2 g / L was reacted with an aluminum sulfate solution with an Al2O3 concentration of 90.2 g / L. After filtration and washing, a silica-alumina gel solution was prepared. The mass data of the silica-alumina gel were: SiO2 61.9%, Al2O3 16.6%, Na2O 13.7%, solid content 11.9%, and density 1.096.

[0044] 137.6 ml of sodium aluminate solution with Al2O3 concentration of 148.2 g / L and Na2O concentration of 181.6 g / L and 261.8 ml of sodium hydroxide solution with a concentration of 31.8% were added to a stirred reactor and stirred evenly. Then, 712.6 ml of water glass solution with SiO2 concentration of 252.6 g / L and modulus of 3.23 was added. The aging temperature was controlled at 25℃ and the mixture was allowed to stand for 22 hours. After aging, 200.2 ml of chemical water was added. The resulting product is the directing agent solution.

[0045] 255.9 ml of the prepared silica-alumina gel solution, 291.2 ml of water glass solution with a SiO2 concentration of 252.6 g / L and a modulus of 3.23, 52.6 ml of sodium aluminate solution, 49.6 ml of directing agent solution, and 67.2 ml of aluminum sulfate solution with an Al2O3 concentration of 91.6 g / L were added concurrently to the gelation reactor. The gelation reaction was carried out at 50°C with stirring for 60 minutes. The temperature was then raised to 98°C, and the mixture was allowed to stand for 28 hours before being washed and filtered to obtain the high silica-alumina ratio molecular sieve support.

[0046] (3) Mix the above-mentioned parent precipitate slurry and high silica-alumina ratio molecular sieve carrier, let stand for 30 minutes, filter, dry and granulate, add 1.5% graphite lubricant and 0.6% sodium cellulose forming agent, and press into tablets to make decarbonyl iron protective agent sample C2.

[0047] Example 3

[0048] (1) Add 300 mL of 1.5 mol / L potassium carbonate solution to 80 mL of 2.0 mol / L Cu and Zn (molar ratio of 1.5:1) mixed nitrate aqueous solution to carry out coprecipitation reaction. The coprecipitation temperature is 70℃. The parent precipitate is washed with deionized water. The pH value during the precipitation process is controlled at 7.5. The final pH value of the filtrate is 7.2. After aging at 90℃ for 10 min, the parent precipitate slurry is obtained.

[0049] (2) Preparation of sodium aluminate solution for the production of high silica-alumina ratio molecular sieves: 500 ml of 30.5% sodium hydroxide solution and 207.99 g of aluminum hydroxide powder with Al2O3 content of 64% were added to a stirred reactor. The reaction pressure was 0.2 MPa, the reaction temperature was 125℃, and the reaction time was 6 h. After filtration, sodium aluminate solution for the production of high silica-alumina ratio molecular sieves was prepared.

[0050] Filtered qualified materials with SiO2 concentration of 45.8 g / L and Al2O3 concentration of 25.2 g / L were reacted with aluminum sulfate solution with Al2O3 concentration of 90.2 g / L. After filtration and washing, a silica-alumina gel was prepared. The mass data of the silica-alumina gel were: SiO2 61.9%, Al2O3 16.6%, Na2O 13.7%, solid content 11.9%, and density 1.096.

[0051] 134.2 ml of sodium aluminate solution with Al2O3 concentration of 152.0 g / L and Na2O concentration of 178.2 g / L and 276.3 ml of sodium hydroxide solution with a concentration of 30.5% were added to a stirred reactor and stirred evenly. Then, 724 ml of water glass solution with SiO2 concentration of 248.6 g / L and modulus of 3.25 was added. The aging temperature was controlled at 28℃ and the mixture was allowed to stand for 20 hours. After aging, 204.8 ml of chemical water was added. The resulting product is the directing agent solution.

[0052] 255.9 ml of silica-alumina gel solution, 295.8 ml of water glass solution with SiO2 concentration of 248.6 g / L and modulus of 3.25, 52.6 ml of sodium aluminate solution, 50 ml of directing agent solution, and 65.0 ml of aluminum sulfate solution with Al2O3 concentration of 89.2 g / L were added concurrently to the gelation reactor. The gelation reaction was carried out at 80°C with stirring for 25 minutes. After the addition was complete, the temperature was raised to 98°C, and the mixture was allowed to stand for 28 hours before being washed and filtered with water.

[0053] (3) Mix the above-mentioned parent precipitate slurry and the high silica-alumina ratio molecular sieve carrier, let stand for 50 min, filter, dry and granulate, add 2% graphite lubricant and 1.0% water forming agent, compress into tablets and prepare carbonyl iron protective agent sample C3.

[0054] Example 4

[0055] (1) Add 200 mL of 2.5 mol / L sodium bicarbonate solution to 50 mL of 2.5 mol / L Cu and Zn (molar ratio of 2:1) mixed nitrate aqueous solution to carry out coprecipitation reaction. The coprecipitation temperature is 80℃. The parent precipitate is washed with deionized water. The pH value is controlled at 8.0 during the precipitation process. The final pH value of the filtrate is 7.5. The parent precipitate slurry is obtained by aging at 30℃ for 100 min.

[0056] (2) Preparation of sodium aluminate solution for the production of high silica-alumina ratio molecular sieves: 500 ml of sodium hydroxide solution with a concentration of 31.0% and 213.066 g of aluminum hydroxide powder with an Al2O3 content of 63.5% were added to a stirred reactor. The reaction pressure was 0.2 MPa, the reaction temperature was 125℃, and the reaction time was 6 h. After filtration, sodium aluminate solution for the production of high silica-alumina ratio molecular sieves was prepared.

[0057] Filtered qualified materials with SiO2 concentration of 45.8 g / L and Al2O3 concentration of 25.2 g / L were reacted with aluminum sulfate solution with Al2O3 concentration of 90.2 g / L. After filtration and washing, a silica-alumina gel was prepared. The mass data of the silica-alumina gel were: SiO2 61.9%, Al2O3 16.6%, Na2O 13.7%, solid content 11.9%, and density 1.096.

[0058] 134.4 ml of sodium aluminate solution with Al2O3 concentration of 151.8 g / L and Na2O concentration of 181.5 g / L and 268.7 ml of sodium hydroxide solution with a concentration of 31% were added to a stirred reactor and stirred evenly. Then, 728.4 ml of water glass solution with SiO2 concentration of 247.1 g / L and modulus of 3.20 was added. The aging temperature was controlled at 25℃ and the mixture was allowed to stand for 22 hours. After aging, 203.8 ml of chemical water was added. The resulting product is the directing agent solution.

[0059] 255.9 ml of silica-alumina gel solution, 294.2 ml of water glass solution with SiO2 concentration of 247.1 g / L and modulus of 3.20, 52.2 ml of sodium aluminate solution, 49.8 ml of directing agent solution, and 65.8 ml of aluminum sulfate solution with Al2O3 concentration of 90.1 g / L were added concurrently to the gelation reactor. The gelation reaction was carried out at 30°C with stirring for 80 minutes. After the addition was complete, the stirring time was increased to 40 minutes. The temperature was raised to 98°C, and the mixture was allowed to stand for 28 hours before being washed and filtered with water.

[0060] (3) Mix the above-mentioned parent precipitate slurry and high silica-alumina ratio molecular sieve carrier, let stand for 80 min, filter, dry and granulate, add 3% graphite lubricant and 0.8% sodium cellulose forming agent, and press into tablets to make decarbonyl iron protective agent sample C4.

[0061] Comparative Example 1

[0062] (1) 200 mL of ammonia solution with a concentration of 4.0 mol / L was added to 70 mL of a mixed nitrate solution of Cu and Zn (molar ratio of 2:1) with a concentration of 3.0 mol / L to carry out a coprecipitation reaction. The coprecipitation temperature was 90℃. The parent precipitate was washed with deionized water. The pH value during the precipitation process was controlled at 6.5. The final pH value of the filtrate was 7.5. The precipitate was aged at 40℃ for 60 min to obtain the parent precipitate slurry.

[0063] (2) Aluminum nitrate and sodium silicate soluble salts are mixed and co-precipitated at a mass percentage of 8%. The final pH value is adjusted to 9.5 according to the different ionization constants of the metal precipitates. The temperature of the mixed solution is controlled at 70℃. After aging and washing, the carrier slurry is obtained.

[0064] (3) The above-mentioned parent slurry and carrier slurry are mixed and pulped, left to stand for 120 minutes, filtered, dried and granulated, and 0.1% graphite lubricant and 0.2% water forming agent are added. After molding, the carbonyl iron protective agent comparison sample C5 is obtained.

[0065] Comparative Example 2

[0066] (1) 150 mL of 3.0 mol / L sodium carbonate solution was added to 50 mL of 2.0 mol / L Cu and Zn (molar ratio of 1:1) mixed nitrate aqueous solution to carry out coprecipitation reaction. The coprecipitation temperature was 80℃. The parent precipitate was washed with deionized water. The pH value during the precipitation process was controlled at 8.0. The final pH value of the filtrate was 7.0. The precipitate was aged at 40℃ for 60 min to obtain the parent precipitate slurry.

[0067] (2) Aluminum nitrate and sodium hydroxide are mixed at a mass percentage of 13% for co-precipitation. The final pH value is adjusted to 9.5 according to the different ionization constants of the metal precipitates. The temperature of the mixed solution is controlled at 70℃. After aging and washing, the carrier slurry is obtained.

[0068] (3) The above-mentioned parent slurry and carrier slurry are mixed and pulped, left to stand for 100 minutes, filtered, dried and granulated to obtain a powder of a certain particle size. After molding with 3% graphite lubricant and 1.0% water forming agent, the decarbonyl iron protective agent comparison sample C6 is obtained.

[0069] The decarbonyl iron removal performance of the protective agents prepared in the examples and comparative examples was evaluated by protective agent activity evaluation tests.

[0070] The molded protective agent was crushed into 20-40 mesh particles, and 2 ml of the sample was placed in a decarbonyl iron reactor for reduction treatment. The reduction atmosphere was an NH mixed gas containing 5% hydrogen by volume, and the reduction temperature was 210℃. The carbonyl iron removal reaction temperature was set according to Table 1, and the synthesis gas space velocity was 12000 h⁻¹. -1The inlet synthesis gas contains 10 ppm of carbonyl iron. After passing through the protective agent in the decarbonyl iron removal reactor, it passes through the methanol catalyst reactor. After the furnace is dismantled, the iron content of the protective agent and the methanol catalyst is analyzed. The iron content of the protective agent is calculated by dividing it by the sum of the iron content in the protective agent and the iron content in the methanol catalyst, which gives the removal rate.

[0071] Table 1. Physicochemical data and carbonyl iron removal performance of the protective agent samples.

[0072]

[0073] As can be seen from the data in Table 1, all the protective agents exhibit the ability to remove iron carbonyl, with removal rates exceeding 94%. Furthermore, under the porous physical adsorption of the molecular sieve support, the copper-zinc based protective agent supported on the molecular sieve demonstrates better activity and a higher capacity for removing iron and nickel. Using the iron carbonyl removal protective agent prepared according to this invention in the protective bed of the methanol synthesis reaction can effectively ensure the longer-term operation of the methanol synthesis catalyst.

[0074] The CO-TPD of different decarbonylation iron protecting agents prepared in the embodiments and comparative examples of this invention are shown in the figure. Figure 1 The CO-TPD of several samples shows that, compared with the control samples C5-C6, the copper-zinc protective agents C1-C4 supported on the molecular sieve have a greater CO adsorption capacity and higher adsorption intensity, while the removal rate of carbonyl iron is higher. This indicates that the protective agent of this molecular sieve system has a better adsorption effect on compounds with carbonyl groups such as Fe(CO)5.

[0075] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A non-reducing syngas decarbonylation iron protecting agent, characterized in that, The active centers of the protective agent are composed of CuO / Cu and ZnO / Zn. The carrier of the protective agent is a high silica-to-alumina molecular sieve, and the remainder consists of lubricant and forming agent. The components of the protective agent, by mass percentage, are: copper oxide content of 0.01%–15.0%, zinc oxide content of 0.01%–10.0%, molecular sieve content of 75.0%–98.0%, lubricant content of 0.1%–3%, and forming agent content of 0.2%–1.0%.

2. The decarbonylation iron protecting agent according to claim 1, characterized in that, The copper oxide content is 2% to 10%, and the zinc oxide content is 2.0% to 10.0%.

3. A method for preparing the decarbonylation iron protecting agent according to claim 1 or 2, characterized in that, Includes the following steps: (1) The active matrix of the protective agent was obtained by co-precipitation with a copper-zinc mixture using the parent precipitant; (2) Using water glass solution, guiding agent solution, aluminum sulfate solution, sodium aluminate solution and silica-alumina gel solution as raw materials, a gelation reaction, aging and post-treatment are carried out to obtain a high silica-alumina ratio molecular sieve carrier. (3) Mix the active matrix of the protective agent obtained in step (1) and the high silica-alumina ratio molecular sieve carrier obtained in step (2), pulverize, let stand, filter, dry and granulate, add lubricant and forming agent to obtain the protective agent.

4. The preparation method according to claim 3, characterized in that, In step (1), the molar ratio of copper and zinc ions in the copper-zinc mixture is 1:2 to 2:1, and the molar concentration of the copper-zinc mixture is 0.1 mol / L to 5 mol / L.

5. The preparation method according to claim 3, characterized in that, In step (1), the parent precipitant is sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution or ammonia water, with a molar concentration of 0.01 mol / L to 4.0 mol / L.

6. The preparation method according to claim 3, characterized in that, In step (1), the temperature of the coprecipitation is 20-90℃, the pH value of the coprecipitation process is controlled at 6.5-8.0, and the final pH value of the coprecipitation is 7.0-7.

5.

7. The preparation method according to claim 3, characterized in that, In step (2), the gelation reaction is controlled to have a molar ratio of Na2O, Al2O3, and SiO2 of 2-3.5:1:8-10.

8. The preparation method according to claim 3, characterized in that, In step (2), the temperature of the gelation reaction is 30-80℃ and the time is 20-80 min; the aging process conditions are: aging at 90-100℃ for 16-40 h.

9. The preparation method according to claim 3, characterized in that, In step (2), the preparation method of the guiding agent solution is as follows: mix sodium aluminate solution and sodium hydroxide solution, stir evenly, add water glass solution, and let stand at 15-40℃ for 8-24 hours to obtain the solution.

10. The preparation method according to claim 3, characterized in that, In step (3), the settling time is 20-100 min.

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