A copper-based catalyst and its application in producing chlorine by hydrogen chloride oxidation

Abstract

The present invention discloses a copper-based catalyst and its application in the production of chlorine by oxidation of hydrogen chloride. The catalyst is composed of Cu 4.8 Ce2V 4.8 O x Solid solution; the catalyst has three active ingredients; among them, active ingredient A is CuO, active ingredient B is CeO2, and active ingredient C is CeVO4. The present invention can change the reaction process and slow down the poisoning rate of the catalyst through the synergistic effect between CuO, CeO2 and CeVO4, and can still stably maintain a high conversion rate under high air intake ratio conditions. In addition, the preparation method provided by the present invention adopts a sol-gel method, which can easily reasonably regulate the surface structure of the metal oxide material by controlling the stirring rate, reaction time, calcination temperature, and the stoichiometric ratio of the preparation process, thereby forming a solid solution structure.

Description

Technical Field

[0001] The invention belongs to the technical field of chlorine preparation, and particularly relates to a copper-based catalyst and application thereof in preparing chlorine by hydrogen chloride oxidation. Background Art

[0002] Chlorine is one of the top ten basic raw materials for the production of chemical products, with a wide range of applications, including in the new materials industry, household fine chemicals, pesticides, pharmaceuticals, new energy, metallurgy, and petrochemicals. The growing demand for chlorine products has led to a severe shortage of chlorine, forcing reliance on imports to sustain industrial development. Furthermore, when chlorinating organic compounds or reacting with phosgene, chlorine atoms utilize less than 50% of the chlorine, resulting in a significant excess of hydrogen chloride gas, necessitating neutralization and disposal. This not only reduces chlorine utilization, but also causes secondary environmental pollution from the discharge of the neutralization solution. Finding new, more economical and environmentally friendly solutions to recycle this byproduct hydrogen chloride is urgent. If chlorine can be produced from hydrogen chloride, which is inexpensive, in low demand, and difficult to process, zero emissions from the recycling and reaction processes within the organic chlorination industry could be achieved.

[0003] Currently, there are three main methods for converting hydrogen chloride into chlorine: electrolysis, direct oxidation, and catalytic oxidation. Electrolysis is expensive and energy-intensive, making it unsuitable for industrial-scale production. The cost of the oxidant used in direct oxidation is also a concern for most factories. In comparison, catalytic oxidation is currently considered the most suitable and effective method in the industrial field.

[0004] Industrially suitable catalysts for catalytic oxidation methods mainly include copper-based catalysts, chromium-based catalysts, ruthenium-based catalysts, and cerium-based catalysts. Currently, the development process of ruthenium-based catalysts in industry has gradually matured. U.S. Patents US 9156024 and US20220080395 and Chinese Patent CN 107952432 A all use ruthenium as the main active phase and add a doping load to synthesize catalysts. Ruthenium-based catalysts exhibit high activity and good stability at low temperatures, but they also face the problem of deactivation at high temperatures. Moreover, ruthenium is a precious metal catalyst, and its cost problem has long plagued the hydrogen chloride catalytic oxidation industry. Therefore, it is urgent to optimize the preparation process of ruthenium catalysts, reduce the content of active components in the catalyst, and reduce the catalyst cost.

[0005] U.S. Patent No. 5707919 describes a method for preparing chlorine using a chromium-based catalyst for the oxidation of hydrogen chloride with an oxygen-containing gas. The catalyst, primarily composed of chromium oxide, offers long-term performance, particularly under low-oxygen conditions, where its activity is less susceptible to degradation. However, in practical applications, the reactor must utilize expensive nickel-based alloys. Nickel is toxic to chromium, and no effective solution has yet been found, limiting its development and use.

[0006] Cerium-based catalysts have good thermal stability and reactivity through doping modification, and have also been a research hotspot in recent years. U.S. Patent US20190023568A1 describes a catalyst material based on cerium oxide, wherein the catalyst comprises at least an oxide compound with cerium oxide as the active component and a catalyst with zirconium dioxide particles as the carrier component. The interaction between CeO2 and the carrier ZrO2 causes the active component CeO2 to form a nano-thin layer on the surface of the carrier, which improves the redox performance of the catalyst to a certain extent; at the same time, ZrO2 as a carrier can stabilize the nanostructure of CeO2 and exhibit good anti-chlorination properties. Cerium-based catalysts can be used as a suitable substitute for precious metal catalysts, but their conversion rate is still somewhat lower than that of ruthenium-based catalysts, so how to further improve the catalytic activity of cerium-based catalysts has also become a problem that many researchers need to consider.

[0007] Chinese patents CN 112044445 A, CN 114713250 A, CN 105642318 B, CN 112044440 A, and CN 106861714B all address the use of copper-based catalysts in the catalytic oxidation of hydrogen chloride. Copper-based catalysts are highly active and low-cost, but finding highly active copper-based catalysts comparable to precious metal catalysts presents a significant challenge in future research into the catalytic oxidation of hydrogen chloride. Copper-based catalysts exhibit excellent catalytic activity above 400°C, but this temperature accelerates the volatilization of the active components in the catalyst, reducing their stability. Therefore, alkali metals or rare earth elements are typically added to improve the dispersion and stability of the active components. While these modified catalysts can achieve conversion rates exceeding 80%, prolonged reaction times can lead to a slightly greater decrease in conversion. While the addition of additives has proven effective in improving stability, the appropriate amount of additives is a cost consideration.

[0008] In most industrial production processes, the hydrogen chloride to oxygen inlet ratio is maintained at 1:1. Under this atmosphere, oxygen is present in large excess, resulting in significant gas costs throughout the production process and a significant challenge in separating and collecting the subsequent gas production. Therefore, reducing the proportion of oxygen in the overall reaction system would be a crucial technological breakthrough. However, currently, many catalysts are poisoned quickly when the hydrogen chloride to oxygen inlet ratio is adjusted to 2:1 due to the increased hydrogen chloride gas content, significantly affecting their stability and causing a significant drop in conversion rate. Maintaining high conversion efficiency and long-term stable operation while increasing the hydrogen chloride to oxygen inlet ratio will be a technical challenge that many companies will need to overcome during the industrialization phase.

[0009] The above categories generally cover most of the catalytic systems currently required for the catalytic oxidation of hydrogen chloride. However, existing technologies still have many deficiencies. Therefore, the continued development of highly active, highly stable, non-toxic, and low-cost catalysts holds great promise for industrial application.

[0010] In addition, existing technologies for modifying copper-based catalysts usually add other components as co-catalysts (such as oxides or chlorides of V, Be, Mg, Bi, and Sb) to the copper catalyst to improve the catalyst activity, or add low-volatility rare earth metals and sodium chloride or potassium chloride. Since sodium or potassium salts form a low azeotrope with copper salts, the volatility of the catalyst is reduced. However, there is still little research on adding multiple elements to copper-based catalysts, and most of them mainly produce high catalytic activity due to the addition of trace precious metals, which has lost the original intention of using copper-based catalysts. Summary of the Invention

[0011] In view of the shortcomings of various existing catalysts for catalytic oxidation of hydrogen chloride to produce chlorine, the object of the present invention is to provide a catalyst for catalytic oxidation of hydrogen chloride to produce chlorine with high activity, high stability, strong chlorine resistance and low cost.

[0012] In the first aspect, the present invention provides a copper-based catalyst, the composition of which is Cu 4.8 Ce2V 4.8 O x Solid solution, in which; Cu 4.8 Ce2V 4.8 O x There are three active components in the solid solution; among them, active component A is CuO, active component B is CeO2, and active component C is CeVO4.

[0013] Preferably, the copper-based catalyst is obtained by preparing a precursor from a metal source containing an active ingredient through a sol-gel method, and then calcining the precursor at a temperature of 450 to 550° C. in an oxygen-containing atmosphere.

[0014] Preferably, the molar ratio of copper, cerium and vanadium in the copper-based catalyst is (4-5.2):2:(4-5.2).

[0015] Preferably, the molar ratio of copper, cerium and vanadium in the copper-based catalyst is 4.8:2:4.8.

[0016] Preferably, the metal source containing the active ingredient is a salt of the corresponding metal of the active ingredient.

[0017] Preferably, the metal source is a water-soluble salt; more preferably, at least one of a nitrate and a sulfate; and most preferably, a nitrate. Studies have found that using a nitric acid source as the raw material and the preparation method of the present invention can unexpectedly produce a catalyst with higher catalytic performance and greater stability. For example, copper nitrate, cerium nitrate, and a complexing agent are thoroughly stirred, dried, and calcined to obtain the catalyst.

[0018] In a second aspect, the present invention provides a method for preparing a copper-based catalyst, comprising the following steps:

[0019] Step 1: Dissolve the precursor salt of CuO and the precursor salt of CeO2 in water, add the first complexing agent, and heat to a gel state.

[0020] Step 2: dissolving ammonium metavanadate and the second complexing agent in water and heating them to a gel state.

[0021] Step 3: Mix the products obtained in steps 1 and 2 and heat and stir.

[0022] Step 4: The gel obtained in step 3 is dried, ground, centrifuged, dried, and calcined in sequence to obtain a copper-cerium-vanadium composite material.

[0023] This preparation method can promote the synergistic dispersion of the various components of the metal source, and can obtain a catalyst with good catalytic stability and activity.

[0024] Preferably, the precursor salt of CuO is copper nitrate; the precursor salt of CeO2 is cerium nitrate (Ce(NO3)6 2- The first complexing agent is citric acid. The second complexing agent is oxalic acid. In step 1, the mass of water is 3 to 5 times the total mass of copper nitrate, cerium nitrate, and citric acid. In step 2, the mass of water is 3 to 5 times the total mass of ammonium metavanadate and oxalic acid.

[0025] Preferably, the molar ratio of citric acid to the sum of the molar amounts of copper nitrate and cerium nitrate in step 1 is 3.5:1. The molar ratio of oxalic acid to ammonium metavanadate in step 2 is 3.5:1.

[0026] Preferably, the heating conditions in steps 1, 2 and 3 are all heating at 80° C. in a water bath with stirring for 4 to 6 hours; the rotor speed of the stirring is 15 rpm.

[0027] Preferably, the centrifugal speed in step 4 is 6000r and the time is 8min.

[0028] Preferably, the calcination process in step 4 is carried out in an oxygen-containing atmosphere, wherein the oxygen-containing atmosphere is a pure gas or a mixed gas containing oxygen; preferably oxygen or air.

[0029] Preferably, the calcination temperature in step 4 is 450-550°C, and the calcination time is 4-6 hours. More preferably, it is 500-550°C. Controlling the calcination temperature helps further improve the catalytic activity and stability of the obtained catalyst.

[0030] Preferably, the drying conditions in step 4 are as follows: drying the gel obtained in step 3 at 100° C. to 110° C. for 10 to 12 hours to prepare a xerogel.

[0031] In a third aspect, the present invention provides a method for producing chlorine by catalytic oxidation of hydrogen chloride. The method comprises: introducing hydrogen chloride and oxygen into a fixed-bed reactor containing a copper-based catalyst, heating at 420°C to 440°C to react, and producing chlorine. The flow ratio of hydrogen chloride to oxygen is (1-2):1.

[0032] In a fourth aspect, the present invention provides use of the aforementioned copper-based catalyst in the catalytic oxidation of hydrogen chloride to produce chlorine.

[0033] The catalyst provided by the present invention has a good catalytic effect in the catalytic oxidation of hydrogen chloride to produce chlorine as follows:

[0034] Cerium-based catalysts and copper-based catalysts themselves have good catalytic activity for hydrogen chloride, and copper-cerium catalysts have always been a major research hotspot. On this basis, the present invention adds vanadium to prevent the rapid deactivation of the catalyst to improve its stability. At the same time, the present invention considers adding metal additives to improve the chlorine resistance of the catalyst under high hydrogen chloride conditions, and innovatively combines it with another idea of ​​solving the catalytic stability of hydrogen chloride by changing the catalytic reaction process. The present invention's research found that the three active ingredients can work together to change the catalytic oxidation reaction process of HCl, thereby significantly improving the catalytic stability of the catalyst.

[0035] When CeO2 is used alone as a catalyst for the catalytic oxidation of hydrogen chloride to chlorine, its activity level is not as high as that of ruthenium-based and copper-based catalysts, and it is also prone to sintering. Therefore, its activity is generally improved by modification, and it is not considered to be used alone. However, in the catalyst prepared by the present invention, the active components A and B can produce a synergistic effect. The presence of CeO2 improves the dispersion of CuO, which significantly enhances the redox performance of the catalyst. Some Cu 2+ Doping CeO2 can increase the concentration of oxygen vacancies on the catalyst surface, which is also the key to the high activity of the catalyst.

[0036] V itself has a good catalytic effect and is often incorporated into the catalyst synthesis step as a catalyst adjuvant. In the present invention, the addition of vanadium can increase the bond energy of the metal-oxygen bond, making it difficult for lattice oxygen to exchange with the chlorine element in hydrogen chloride, preventing chlorine from binding to the surface of the metal element, thereby effectively preventing catalyst poisoning.

[0037] Multiple experimental observations revealed that throughout the reaction, HCl molecules are preferentially adsorbed into the lattice oxygen of CuO, while a portion is adsorbed into surface oxygen vacancies on the catalyst. During this reaction, Cl occupies oxygen vacancies in the catalyst, poisoning it. The presence of CeVO4 and CeO2 significantly enhances O2 adsorption, replacing Cl in catalyst vacancies with O2. Furthermore, CuO, acting as the most favorable active site during Cl2 desorption, helps reduce Cl accumulation on the CeO2 and CeVO4 surfaces. This combination of factors is crucial for maintaining the high activity and stability of the catalyst.

[0038] The beneficial effects of the present invention are:

[0039] To alleviate copper loss in a high-temperature hydrogen chloride atmosphere, existing technologies mostly employ the addition of promoters or rare earth elements to form high-boiling-point double salts to improve their stability. Unlike existing technologies, the present invention proposes a solution to the hydrogen chloride catalyst stability issue by combining the synergistic effect of active substances with promoter doping.

[0040] 2. Cu provided by the present invention 4.8 Ce2V 4.8 O x There is a synergistic effect between CuO, CeO2 and CeVO4 in the solid solution, which can change the reaction process and slow down the poisoning rate of the catalyst, and can still stably maintain a high conversion rate under high intake ratio conditions.

[0041] 3. The preparation method provided by the present invention adopts the sol-gel method, which can easily reasonably regulate the surface structure of the metal oxide material by controlling the stirring rate, reaction time, calcination temperature, and the stoichiometric ratio of the preparation process, thereby forming a solid solution structure.

[0042] 4. This catalyst synthesizes a solid solution structure, where vanadium ions are incorporated into the ceria lattice by substitution. Due to the size mismatch with the cerium cation, the bound vanadium cation does not fit neatly into the standard position. This mismatch leads to the formation of a large number of oxygen vacancies, which is also a key reason for the catalyst's stable conversion performance and high conversion rate.

[0043] 5. The catalyst obtained under the innovative mechanism of the present invention has good chlorine resistance, catalytic stability and catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a comparison chart of the performance of the catalysts prepared in Examples 1-4 of the present invention in preparing chlorine.

[0045] Figure 2 The Cu prepared in Example 3 of the present invention 4.8 Ce2V4O x Performance diagram of catalyst feed ratio gradient experiment.

[0046] Figure 3 This is a performance comparison chart of the catalysts prepared in Examples 5-8 of the present invention for preparing chlorine.

[0047] Figure 4 This is a test chart of the time it takes for the catalyst prepared in Example 10 of the present invention to prepare chlorine under the condition of HCl / O2=1.

[0048] Figure 5 This is a test chart of the time it takes for the catalyst prepared in Example 10 of the present invention to prepare chlorine under the condition of HCl / O2=2.

[0049] Figure 6 This is the XRD characterization diagram of the catalyst prepared in Example 10 of the present invention.

[0050] The stability test of the catalysts in Examples 1-4 was carried out. It can be seen from the figure that during the 12-hour continuous test, Cu 4.8 Ce2V4O x The catalyst showed good stability and maintained high activity, with an HCl conversion rate of over 94%. As the ratio of hydrogen chloride to oxygen in the intake air gradually increased, the conversion rate of the catalyst decreased. Under the condition of HCl / O2=1, the hydrogen chloride conversion rate was the highest. In order to demonstrate the chlorine resistance of the catalyst, the activity of the catalysts in Examples 8-11 was tested under the condition of HCl / O2=2, and it was found that Cu 4.8Ce2V 4.8 O x The catalyst has the best chlorine resistance, with an HCl conversion rate of 89% and can operate stably for 100 hours; 4.8 Ce2V 4.8 O x The catalyst was tested for life under the condition of HCl / O2=1, and it was found that it could operate stably for 600 hours with a conversion rate of 94%. Combined with the cost advantage of the catalyst of the present invention, it shows good application prospects.

[0051] The characteristic peaks of monoclinic CuO (ISCD 202425), face-centered cubic CeO2 (ISCD 24887) and tetragonal body-centered CeVO4 (ISCD 16025) in the catalyst were further verified by XRD results. 4.8 Ce2V 4.8 O x The size is similar to that of fresh samples, and no obvious sintering phenomenon occurs. DETAILED DESCRIPTION

[0052] The present invention will be further described below with reference to the accompanying drawings.

[0053] Example 1

[0054] A copper-based catalyst (Cu4Ce2V4O x ), prepared by the following method:

[0055] Step 1: Take a beaker and mix 6.52gCu(NO3)2 and 5.12gCe(NO3)6 2- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0056] Step 2: In another beaker, dissolve 2.34g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat in a water bath at 80℃ until it becomes gel-like.

[0057] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0058] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at 105°C, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 1.

[0059] The molar ratio of Cu, Ce and V in the copper-based catalyst provided in this embodiment is 4:2:4.

[0060] 2 g of the copper-based catalyst provided in this example was placed in a fixed bed reactor.

[0061] Step b. The gases were introduced into a fixed bed reactor at a flow rate of 10 ml / min of hydrogen chloride and 10 ml / min of oxygen (HCl / O2 = 1). The reaction was conducted at 434°C and the conversion of hydrogen chloride was 75%.

[0062] Example 2

[0063] A copper-based catalyst (Cu 4.4 Ce2V4O x ), prepared by the following method:

[0064] Step 1: Take a beaker and mix 7.17gCu(NO3)2 and 5.12gCe(NO3)6 2- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0065] Step 2: Take another beaker, dissolve 2.34g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat it in a water bath at 80℃ until it becomes gel-like.

[0066] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0067] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 2.

[0068] The molar ratio of Cu, Ce and V in the copper-based catalyst provided in this embodiment is 4.4:2:4.

[0069] 2 g of the copper-based catalyst provided in this example was placed in a fixed bed reactor.

[0070] Step b. The gases were introduced into a fixed bed reactor at a hydrogen chloride flow rate of 10 ml / min and an oxygen flow rate of 10 ml / min (HCl / O2 = 1). The reaction was conducted at 434°C and the hydrogen chloride conversion was 92%.

[0071] Example 3

[0072] A copper-based catalyst (Cu 4.8 Ce2V4O x ), prepared by the following method:

[0073] Step 1: Take a beaker and mix 7.82gCu(NO3)2 and 5.12gCe(NO3)62- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0074] Step 2: Take another beaker, dissolve 2.34g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat it in a water bath at 80℃ until it becomes gel-like.

[0075] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0076] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 3.

[0077] The molar ratio of Cu, Ce and V in the copper-based catalyst provided in this embodiment is 4.8:2:4.

[0078] 2 g of the copper-based catalyst provided in this example was placed in a fixed bed reactor.

[0079] Step b. The gases were introduced into a fixed bed reactor at a hydrogen chloride flow rate of 10 ml / min and an oxygen flow rate of 10 ml / min (HCl / O2 = 1). The reaction was conducted at 434°C and the hydrogen chloride conversion was 94%.

[0080] Example 4

[0081] A copper-based catalyst (Cu 5.2 Ce2V4O x ), prepared by the following method:

[0082] Step 1: Take a beaker and mix 8.47gCu(NO3)2 and 5.12gCe(NO3)6 2- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0083] Step 2: Take another beaker, dissolve 2.34g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat it in a water bath at 80℃ until it becomes gel-like.

[0084] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0085] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 4.

[0086] The molar ratio of Cu, Ce, and V in the copper-based catalyst provided in this embodiment is 5.2:2:4.

[0087] 2 g of the copper-based catalyst provided in this example was placed in a fixed bed reactor.

[0088] Step b. The gases were introduced into a fixed bed reactor at a flow rate of 10 ml / min of hydrogen chloride and 10 ml / min of oxygen (HCl / O2 = 1). The reaction was conducted at 434°C and the conversion of hydrogen chloride was 70%.

[0089] In combination with Examples 1-4, the effects of different copper addition amounts on the performance of the copper-cerium-vanadium catalyst are compared and are shown in Table 1 below.

[0090] Table 1 Comparison of the effects of different copper addition amounts on the performance of copper-cerium-vanadium catalysts

[0091]

[0092] Combined with Table 1 and Figure 1 It can be seen that under the condition of HCl / O2 = 1, the addition of copper has a significant impact on the performance of the copper-cerium-vanadium catalyst. When the copper-cerium-vanadium ratio is 4.4:2:4 or 4.8:2:4, the hydrogen chloride conversion rate is high. When the copper addition is too high or too low, the hydrogen chloride conversion rate will drop rapidly.

[0093] Example 5

[0094] A method for preparing chlorine comprises the following steps:

[0095] Step a. 2g of Cu prepared in Example 3 4.8 Ce2V4O x The catalyst is loaded into a fixed bed reactor.

[0096] Step b. The gases were introduced into a fixed bed reactor at a flow rate of 11 ml / min of hydrogen chloride and 9 ml / min of oxygen (HCl / O2 = 1.2), the reaction temperature was 434°C, and the reaction was continued.

[0097] After 72 hours of reaction, the hydrogen chloride conversion rate was stabilized at 92%, and the catalyst activity remained unchanged.

[0098] Example 6

[0099] Step a. 2g of Cu prepared in Example 3 4.8 Ce2V4O xThe catalyst is loaded into a fixed bed reactor.

[0100] Step b. The gases were introduced into a fixed bed reactor at a flow rate of 12 ml / min of hydrogen chloride and 8 ml / min of oxygen (HCl / O2 = 1.5), the reaction temperature was 434°C, and the reaction was continued.

[0101] After 72 hours of reaction, the hydrogen chloride conversion rate was stabilized at 88%, and the catalyst activity remained unchanged.

[0102] Example 7

[0103] Step a. 2g of Cu prepared in Example 3 4.8 Ce2V4O x The catalyst is loaded into a fixed bed reactor.

[0104] Step b. The gases were introduced into the fixed bed reactor at a flow rate of 13 ml / min of hydrogen chloride and 7 ml / min of oxygen (HCl / O2 = 1.8), the reaction temperature was 434°C, and the reaction was continued.

[0105] After 72 hours of reaction, the hydrogen chloride conversion rate was stabilized at 85%, and the catalyst activity remained unchanged.

[0106] Example 8

[0107] Step a. 2g of Cu prepared in Example 3 4.8 Ce2V4O x The catalyst is loaded into a fixed bed reactor.

[0108] Step b. The gases were introduced into a fixed bed reactor at a hydrogen chloride flow rate of 13.3 ml / min and an oxygen flow rate of 6.6 ml / min (HCl / O2 = 2), the reaction temperature was 434°C, and the reaction was continued.

[0109] After 72 hours of reaction, the hydrogen chloride conversion rate was stabilized at 83%, and the catalyst activity remained unchanged.

[0110] In combination with Examples 1-4, the comparative results of the effects of different HCl / O2 molar ratios on the conversion of hydrogen chloride are shown in Table 2 below.

[0111] Table 2 Feed molar ratio of HCl / O2 to Cu 4.8 Ce2V4O x Impact of catalyst performance

[0112]

[0113]

[0114] Combined with Table 2 and Figure 2It can be seen that under the condition of HCl / O2=1, the hydrogen chloride conversion rate is the highest; when the inlet gas molar ratio gradually increases, the hydrogen chloride conversion rate also shows a slightly downward trend.

[0115] Example 9

[0116] A copper-based catalyst (Cu 4.8 Ce2V 4.4 O x ), prepared by the following method:

[0117] Step 1: Take a beaker and mix 7.82g Cu(NO3)2 and 5.12g Ce(NO3)6 2- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0118] Step 2: Take another beaker, dissolve 2.57g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat it in a water bath at 80℃ until it becomes gel-like.

[0119] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0120] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 9.

[0121] The molar ratio of Cu, Ce, and V in the copper-based catalyst provided in this embodiment is 4.8:2:4.4.

[0122] 2 g of the copper-based catalyst provided in this example was placed in a fixed-bed reactor. Gas was introduced into the fixed-bed reactor at a hydrogen chloride flow rate of 13.3 ml / min and an oxygen flow rate of 6.6 ml / min (HCl / O2 = 2). The reaction was conducted at 434°C, and the hydrogen chloride conversion rate was measured to be 87%.

[0123] Example 10

[0124] A copper-based catalyst (Cu 4.8 Ce2V 4.8 O x ), prepared by the following method:

[0125] Take a beaker and mix 7.82gCu(NO3)2 and 5.12g Ce(NO3)6 2-Dissolve in 100ml of deionized water, add 20g of citric acid as a complexing agent, and then heat at 80°C until a gel-like precursor is obtained. In another beaker, dissolve 2.81g of NH₄VO₃ and 6g of H₂C₂O₄ in 50ml of deionized water. Heat in a water bath at 80°C until a gel forms. Combine the products from steps 1 and 2 in the two beakers and stir at the same temperature for approximately 4 hours to obtain the final gel.

[0126] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 10.

[0127] The XRD characterization diagram of the catalyst prepared in this example is as follows: Figure 6 The molar ratio of Cu, Ce and V in the copper-based catalyst provided in this embodiment is 4.8:2:4.8.

[0128] 2 g of the copper-based catalyst provided in this example was placed in a fixed-bed reactor. Gas was introduced into the fixed-bed reactor at a hydrogen chloride flow rate of 13.3 ml / min and an oxygen flow rate of 6.6 ml / min (HCl / O2 = 2). The reaction was conducted at 434°C, and the hydrogen chloride conversion rate was measured to be 89%.

[0129] Example 11

[0130] A copper-based catalyst (Cu 4.8 Ce2V 5.2 O x ), prepared by the following method:

[0131] Step 1: Take a beaker and mix 7.82g Cu(NO3)2 and 5.12g Ce(NO3)6 2- Dissolved in 100 ml of deionized water, 20 g of citric acid was added as a complexing agent, and then heated at 80 °C to obtain a gel-like precursor.

[0132] Step 2: Take another beaker, dissolve 3.04g NH4VO3 and 6g H2C2O4 in 50ml deionized water, and heat it in a water bath at 80℃ until it becomes gel-like.

[0133] Step 3: Mix the products in the two beakers obtained in steps 1 and 2, and stir at the same temperature for about 4 hours to obtain the final gel.

[0134] Step 4: Place the gel obtained in step 3 in an oven at 105°C and dry for 12 hours, take it out, grind it, centrifuge it, dry it at the same temperature, and place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst 11.

[0135] The molar ratio of Cu, Ce, and V in the copper-based catalyst provided in this embodiment is 4.8:2:5.2.

[0136] 2 g of the copper-based catalyst provided in this example was placed in a fixed-bed reactor. Gas was introduced into the fixed-bed reactor at a hydrogen chloride flow rate of 13.3 ml / min and an oxygen flow rate of 6.6 ml / min (HCl / O2 = 2). The reaction was conducted at 434°C, and the hydrogen chloride conversion rate was measured to be 85%.

[0137] In combination with Examples 3, 8-11, the effects of different addition amounts of vanadium elements on the performance of the copper-cerium-vanadium catalyst are compared and shown in Table 3 below.

[0138] Table 3 Comparison of the effects of different vanadium addition amounts on the performance of copper-cerium-vanadium catalysts

[0139]

[0140]

[0141] Combined with Table 3 and Figure 3 It can be seen that when the intake ratio is increased to HCl / O2=2, the conversion rate of the catalyst with the initial vanadium content drops to 83%. As the amount of vanadium added gradually increases, the conversion rate shows a trend of first increasing and then decreasing, but it is higher than the initial value. When the copper-cerium-vanadium ratio is 4.8:2:4.8, the chlorine resistance effect is the best, and the conversion rate is 89%.

[0142] In order to prove the stability and reusability of the catalyst provided by the present invention, a long-term test was carried out, and the results are as follows Figure 4 and 5 shown by Figure 4 It can be seen that the catalyst was not deactivated during the 600-hour laboratory test, and the catalyst particles were well dispersed, without obvious sintering, showing good stability, and the hydrogen chloride conversion rate remained above 90%; and Figure 5 When the feed gas ratio of HCl:O2 is increased to 2:1, the catalyst can also operate stably for 100 hours at a conversion rate of 89%. Compared with the currently expensive copper-based catalysts, it shows extremely similar activity and stability, as well as better chlorine resistance.

Claims

1. A copper-based catalyst, characterized in that: Composition is Cu 4.8 Ce2V 4.8 O x solid solution; Cu 4.8 Ce2V 4.8 O x There are three active components in the solid solution, namely CuO, CeO2 and CeVO4.

2. A copper-based catalyst according to claim 1, characterized in that: The copper-based catalyst is obtained by preparing a precursor from a metal source containing an active component through a sol-gel method, and then calcining the precursor at a temperature of 450-550° C. in an oxygen-containing atmosphere.

3. A method for preparing a copper-based catalyst, characterized in that: For preparing a copper-based catalyst according to claim 1, the preparation method comprises the following steps: Step 1: dissolving a CuO precursor salt and a CeO2 precursor salt in water, adding a first complexing agent, and heating to a gel state; Step 2: dissolving ammonium metavanadate and a second complexing agent in water and heating them to a gel state; Step 3: Mix the products obtained in steps 1 and 2 and heat and stir; Step 4: The gel obtained in step 3 is dried, ground, centrifuged, dried, and calcined in sequence to obtain a copper-cerium-vanadium composite material.

4. The preparation method according to claim 3, wherein: The heating conditions in steps 1, 2 and 3 are all heating at 80°C in a water bath with stirring for 4 to 6 hours.

5. The preparation method according to claim 3, wherein: The CuO precursor salt is copper nitrate; the CeO2 precursor salt is cerium nitrate; the first complexing agent is citric acid; and the second complexing agent is oxalic acid. In step one, the mass of water is 3 to 5 times the total mass of copper nitrate, cerium nitrate and citric acid; and in step two, the mass of water is 3 to 5 times the total mass of ammonium metavanadate and oxalic acid.

6. The preparation method according to claim 3, wherein: The calcination conditions in step 4 are: calcination at a calcination temperature of 450-550° C. in an oxygen-containing atmosphere for 4-6 hours; the oxygen-containing atmosphere is a pure gas or a mixed gas containing oxygen.

7. A method for producing chlorine by catalytic oxidation of hydrogen chloride, characterized in that: Hydrogen chloride and oxygen are introduced into a fixed bed reactor containing the copper-based catalyst according to any one of claims 1 to 2, and heated at 420° C. to react to produce chlorine; the flow ratio of hydrogen chloride to oxygen is (1-2):

1.

8. Use of a copper-based catalyst as claimed in any one of claims 1 to 2 in the catalytic oxidation of hydrogen chloride to produce chlorine.

Images