Catalyst for catalytic oxidation of hydrogen chloride to chlorine, preparation method thereof and application

Abstract

The present invention provides a catalyst for the catalytic oxidation of hydrogen chloride to chlorine, a preparation method thereof, and an application thereof. The catalyst provided by the present invention can still stably exhibit catalytic activity after long-term use in the reaction of catalytic oxidation of hydrogen chloride to chlorine. The catalyst has good stability and is not prone to caking during the application process. The catalyst comprises a first precursor and a second precursor wrapping the first precursor; the first precursor comprises a carrier; the second precursor comprises a wrapping material wrapping the first precursor; active components are respectively loaded on the carrier and the wrapping material, and the active components comprise copper elements; the mass of copper elements in the first precursor accounts for 4-18% of the mass of the first precursor; the mass of copper elements in the second precursor accounts for 1-6% of the mass of the second precursor.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic oxidation of hydrogen chloride to chlorine, and particularly relates to a catalyst for catalytic oxidation of hydrogen chloride to chlorine, a preparation method thereof, and an application thereof. Background Art

[0002] As an important basic chemical raw material, chlorine is widely used in the production of PVC, polyurethane intermediates (such as MDI, TDI, HDI, etc.), epoxy resins, silicone, synthetic rubbers, chlorofluorocarbons, TiO2 coatings, organic chlorine intermediates (such as chlorobenzene, chloroacetic acid, benzyl chloride, chlorotoluene, etc.), and some chlorine-consuming products such as agrochemicals, building materials, and some pharmaceutical preparations. It is known that chlorine can be prepared by catalytic oxidation of hydrogen chloride, and the key to this technology lies in the development of highly efficient catalysts.

[0003] Among the reported hydrogen chloride oxidation catalysts, the active components are mainly metal elements such as copper, chromium, gold, and ruthenium. Among them, gold and ruthenium-based catalysts are expensive and have poor sulfur resistance, while chromium-based catalysts pollute the environment due to their high toxicity. In contrast, copper-based catalysts have the dual advantages of low cost and environmental protection, and thus have attracted much attention.

[0004] Since Deacon developed a hydrogen chloride oxidation to chlorine catalyst with CuCl2 as the active component in 1868, copper-based catalysts have made great progress. In the existing literature system, a complete Cu-based catalyst generally includes a carrier, copper element, alkali metal element, rare earth metal element, and additives. It is known that for Cu-based catalysts, copper elements are easily migrated to the catalyst surface, and after long-term use, the catalyst is prone to caking and agglomeration, resulting in blockage of fixed-bed reactors and bed collapse in fluidized-bed reactors, which limits the long-term stable operation of industrial plants. And copper elements will volatilize out of the reactor in the form of copper chloride and condense in pipelines or heat exchangers with lower temperatures. Especially in the presence of a large amount of catalysts, even a small amount of loss is likely to cause blockage of pipelines, resulting in production interruption. At the same time, the loss of Cu elements also leads to a decrease in catalyst activity. Therefore, the migration of copper elements greatly limits the activity and long-term stability of the catalyst.

[0005] Aiming at the problems of the above-mentioned Cu-based catalysts, a large number of literatures mainly focus on improving the formulation of the catalyst active components, and there are few reports on adjusting the distribution of copper elements in the catalyst.

[0006] US3260678A reports a copper-containing catalyst supported on silica gel, which requires that the specific surface area of the carrier > 200m 2 / g, with an average pore diameter > 6 nm. The HCl conversion rate of this catalyst reaches 80% at 350 °C. However, according to Example 1, the reaction space velocity of the reaction is very low, being 40 L(HCl)*kg(cat) -1 *h -1 .

[0007] CN101125297A discloses a catalyst with copper chloride, potassium chloride, and cerium chloride supported on an alumina support. The hydrogen chloride conversion rate can reach 80.1%, but there is still a phenomenon of easy loss of active components, which affects the catalyst life.

[0008] Based on the above research background, it is necessary to develop a catalyst with high activity and long-term stability. Summary of the Invention

[0009] In view of this, the present invention provides a catalyst for catalytic oxidation of hydrogen chloride to chlorine, its preparation method and application. The catalyst provided by the present invention can still stably exhibit catalytic activity after long-term use in the reaction of catalytic oxidation of hydrogen chloride to chlorine. The catalyst has good stability and is not prone to caking during the application process.

[0010] The present invention provides the following technical solutions to achieve its purpose:

[0011] The present invention provides a catalyst for catalytic oxidation of hydrogen chloride to chlorine, where the catalyst includes a first precursor and a second precursor that wraps the first precursor;

[0012] The first precursor includes a support;

[0013] The second precursor includes a wrapping material that wraps the first precursor;

[0014] Active components are respectively loaded on the support and the wrapping material, and the active components include copper element;

[0015] The mass of copper element in the first precursor accounts for 4 - 18% of the mass of the first precursor;

[0016] The mass of copper element in the second precursor accounts for 1 - 6% of the mass of the second precursor.

[0017] In the catalyst provided by the present invention, the copper element is distributed in a specific ratio in the first precursor inside and the second precursor outside, which can effectively improve the problems of easy caking of the catalyst and affecting the stable operation of the production device. The provided catalyst has good catalytic activity and is not prone to agglomeration during use. The catalyst provided by the present invention has the characteristics of long service life, can be used for a long period of time, and stably exerts catalytic activity. If the content of the copper element in the first precursor is too high, it is easy to cause the catalyst to become sticky, and if the content of the copper element in the second precursor is too high, it is also easy to cause the catalyst to become sticky. By adopting the specific copper element distribution of the present invention, good catalyst activity can be taken into account, and the catalyst is not prone to agglomeration and can be used stably for a long period of time.

[0018] In a preferred embodiment, based on the total mass of the catalyst, the mass percentage of the copper element is 1-15%, preferably 1.5-13 wt%, more preferably 2-10 wt%;

[0019] In some embodiments, the active component further includes an alkali metal element and a rare earth element;

[0020] Preferably, the alkali metal element is selected from one or two of potassium and sodium, and the rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium, and samarium;

[0021] Preferably, based on the total mass of the catalyst, the mass percentage of the alkali metal element is 0.1-8 wt%, preferably 1-7.5 wt%, more preferably 1.2-7 wt%; the mass percentage of the rare earth element is 1.5-15 wt%, preferably 2-14 wt%, more preferably 2.5-13.5 wt%; adopting the above active components with preferred mass percentages in the catalyst is beneficial to obtaining a catalyst with excellent catalytic activity.

[0022] In a preferred embodiment, based on the total mass of the catalyst, the mass percentage of the first precursor is 10-60%. If the mass ratio of the first precursor is too high, it may cause the catalyst to be easily sticky, and if it is too low, it may affect the catalyst activity; controlling the mass ratio of the first precursor in the catalyst within the above preferred range is beneficial to taking into account the improvement of the activity and stability of the catalyst.

[0023] Preferably, in the first precursor, the mass percentage of the carrier is 77-97%;

[0024] In the second precursor, the mass percentage of the wrapping material is 70-90%.

[0025] In some embodiments, the carrier is selected from one or more of alumina, silica, and titania; preferably, the carrier is selected from a composition of alumina and silica, and more preferably, the Si / Al mass ratio of silica to alumina in the carrier is 0.001 - 0.3:1; the inventors have found that using the preferred silica-alumina composite carrier is beneficial to further improve the catalyst activity and long-term use stability.

[0026] In some embodiments, the coating material includes alumina, preferably a composition of alumina and silica; more preferably, the mass ratio of the silica to the alumina in the coating material is preferably 0.3 - 1.5:1. The inventors have found that using the preferred silica-alumina composite coating material is beneficial to maintaining high activity and good stability of the catalyst.

[0027] In some embodiments, the specific surface area of the catalyst is 50 - 300 m 2 / g, more preferably 70 - 280 m 2 / g; the pore volume is 0.1 - 0.9 mL / g, more preferably 0.13 - 0.85 mL / g. The specific surface area and pore volume can be measured by N2 physical adsorption method.

[0028] The present invention also provides a method for preparing the catalyst as described above, comprising the following steps:

[0029] 1) Impregnating the carrier with an aqueous solution containing a first soluble salt, and obtaining a first precursor by calcination, wherein the first soluble salt includes a soluble copper salt;

[0030] 2) Contacting the first precursor obtained in step 1) with a coating raw material and enabling the coating raw material to coat the first precursor, and obtaining a first precursor coated with a coating material by drying and calcination;

[0031] Then impregnating the first precursor coated with the coating material with an aqueous solution containing a second soluble salt, and obtaining a catalyst with a second precursor coated on the first precursor by drying; the second soluble salt includes a soluble copper salt.

[0032] In some embodiments, in step 1), the carrier is selected from a combination of one or more of alumina, silica, and titania; preferably, the carrier is selected from a composition of alumina and silica, and more preferably, the Si / Al mass ratio of silica to alumina in the carrier is 0.001 - 0.3:1.

[0033] Preferably, the specific surface area of the carrier is 100 - 300 m 2 / g, and the pore volume is 0.1 - 0.95 mL / g; more preferably, the specific surface area of the carrier is 120 - 280 m2 / g, and the pore volume is 0.15 - 0.92 mL / g; using a carrier with preferred characteristics is beneficial to further improve the activity and stability of the catalyst.

[0034] In some embodiments, in step 2), the coating raw material includes a sol containing aluminum element; preferably, the coating raw material is a composition of a sol containing aluminum element and a sol containing silicon element. Using these two sol compositions as the coating raw material is beneficial to obtaining a catalyst with good comprehensive performance.

[0035] Preferably, the sol containing aluminum element is obtained by peptizing pseudoboehmite with a dilute acid aqueous solution having a concentration of 3 - 12 wt%. Preferably, the dosage of the dilute acid aqueous solution is 3 - 12% of the mass of the pseudoboehmite; providing the sol containing aluminum element in a preferred manner is beneficial to improving the fluidization performance of the obtained catalyst.

[0036] In some embodiments, in step 2), the second soluble salt further includes soluble salts of alkali metal elements and soluble salts of rare earth elements; preferably, the alkali metal element is selected from one or two of potassium and sodium, and the rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium, and samarium. Preferably, the first soluble salt does not include soluble salts of alkali metal elements and soluble salts of rare earth elements, that is, alkali metal elements and rare earth elements are both loaded in step 2) instead of in step 1). Adopting such a loading method can further improve the catalytic activity and enhance the catalyst performance.

[0037] In the present invention, the soluble salts of copper element, alkali metal elements, and rare earth elements can be in the form of soluble salts commonly used in the art. For example, the soluble salt of copper element can be copper nitrate, copper chloride, copper acetate, or a copper source in any proportion mixture thereof, etc.; the soluble salts of alkali metal elements are, for example, potassium chloride, sodium chloride, etc., and the soluble salts of rare earth elements are, for example, cerium nitrate, cerium chloride, samarium nitrate, etc.

[0038] In some embodiments, in step 1), the calcination conditions include: the calcination temperature is 200 - 660 °C, preferably 260 - 500 °C; the calcination time is 0.5 h - 8 h, preferably 1 h - 6 h;

[0039] In some embodiments, in step 2), the calcination conditions include: the calcination temperature is 300 - 700 °C, preferably 350 - 650 °C; the calcination time is 0.5 h - 10 h, preferably 1 h - 8 h;

[0040] In some embodiments, in step 2), the conditions for drying after the impregnation include: a drying temperature of 90 - 500°C, preferably 100 - 450°C. Drying the catalyst after impregnation in step 2) at a relatively low temperature is conducive to obtaining a catalyst with better activity; the drying time is 0.5 h - 6 h, preferably 1 h - 4 h.

[0041] The present invention also provides a method for preparing chlorine by the oxidation of hydrogen chloride. The hydrogen chloride is oxidized in the presence of a catalyst to prepare the chlorine, and the catalyst is the catalyst described above or the catalyst prepared by the method described above. This method can be carried out in a fixed-bed or fluidized-bed reactor, and the reaction conditions can be conventional in the art. In some embodiments, the maximum reaction temperature can be 300 - 420°C, preferably 320 - 400°C.

[0042] The technical solution provided by the present invention has the following beneficial effects:

[0043] The catalyst provided by the present invention has good catalytic activity in the reaction of preparing chlorine by the oxidation of hydrogen chloride, and the catalyst has good stability, can be used for a long period and maintain good catalytic activity. The catalyst is not easy to agglomerate during use, and can effectively reduce the possibility of equipment blockage. Detailed Embodiments

[0044] To facilitate the understanding of the present invention, the present invention will be further described below in conjunction with embodiments. It should be understood that the following embodiments are only for better understanding of the present invention, and do not mean that the present invention is limited only to the following embodiments.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The term "and / or" as used herein may include any and all combinations of one or more of the related listed items.

[0046] For the parts not specifying the specific experimental steps or conditions in the embodiments, the operations or conditions of the corresponding conventional experimental steps in the technical field of the present invention can be followed. For the reagents or instruments not specifying the manufacturers, they are all conventional products that can be obtained through commercial purchase. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0047] The test methods used in the following examples or comparative examples are introduced below:

[0048] 1. Catalyst performance test method

[0049] Put 10 g of the catalyst into a quartz reactor with an inner diameter of 20 mm and a height of 400 mm. Using a mixed gas with a mass ratio of hydrogen chloride / oxygen = 2 / 1 as the raw material, carry out the reaction of hydrogen chloride oxidation to chlorine under the conditions of an HCl mass space velocity of 0.40 h -1 、a reaction temperature of 350 - 360 °C, and an atmospheric pressure reaction pressure.

[0050] 2. Test method for hydrogen chloride conversion rate and chlorine yield:

[0051] After the above-mentioned reaction of hydrogen chloride oxidation to chlorine is completed, the product gas is introduced into a 15% by mass potassium iodide aqueous solution for absorption. The iodine in the absorption solution is titrated with a 0.1 mol / L sodium thiosulfate aqueous solution, and the residual HCl amount in the absorption solution is titrated with a 0.1 mol / L sodium hydroxide aqueous solution to calculate the amount of chlorine generated and the amount of residual HCl.

[0052] 3. Perform elemental analysis on the catalyst sample using ICP testing.

[0053] 4. Characterize the pore structure and specific surface area of the catalyst using nitrogen physical adsorption.

[0054] Example 1

[0055] 1) Catalyst preparation:

[0056] (1) Preparation of the first precursor

[0057] Weigh 37.02 g of copper chloride and dissolve it in 41.5 g of deionized water. After complete dissolution, spray the obtained solution onto 77 g of an alumina-silica carrier to obtain precursor 1. Use a muffle furnace to calcine precursor 1 at 450 °C for 2 hours to obtain precursor 2 (i.e., the first precursor). Among them, the silicon / aluminum mass ratio in the alumina-silica carrier is 0.05:1, the specific surface area of the carrier is 240 m 2 / g, and the pore volume is 0.85 mL / g.

[0058] (2) Coating the second precursor on the first precursor

[0059] Weigh 59.7 g of pseudoboehmite, peptize it with 7.6 g of dilute nitric acid solution (concentration 10 wt%), add 300 g of 20 wt% silica sol, and the precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 600 °C for 3 hours to obtain catalyst precursor 3.

[0060] Weigh 18.6 g of copper nitrate, 31.9 g of cerium nitrate, 8.7 g of lanthanum chloride, 13.9 g of neodymium nitrate, and 5.2 g of sodium chloride, and dissolve them in 124 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0061] Dry the above catalyst precursor 4 at 200 °C for 4 hours, thereby coating the second precursor on the first precursor, and thus obtaining the finished catalyst.

[0062] In the obtained catalyst, the mass percentage of copper element in the first precursor is 16.5%; the mass percentage of copper element in the second precursor is 1.8%;

[0063] Based on the total mass of the catalyst, the mass percentage of copper element is 8.2 wt%, the mass percentage of cerium element is 4.5 wt%, the mass percentage of lanthanum element is 1.5 wt%, the mass percentage of neodymium element is 2 wt%, the mass percentage of potassium element is 1.5 wt%, and the mass percentage of the first precursor is 41.2 wt%; in the first precursor, the mass percentage of the carrier is 81.6 wt%; in the second precursor, the mass percentage of the coating material is 85.2 wt%, and the mass ratio of silicon to aluminum in the coating material is 1.32:1.

[0064] The specific surface area of the obtained catalyst is 190 m 2 / g; the pore volume is 0.75 mL / g.

[0065] 2). Catalyst performance test:

[0066] Using the above "catalyst performance test method", evaluate the activity of the catalyst. React at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reaches 86.2%. After continuous operation for 4000 hours, the HCl conversion rate reaches 86.5%. After the reaction is completed and the catalyst is removed, it is found that the catalyst does not agglomerate and has good fluidity.

[0067] Example 2

[0068] 1) Catalyst preparation:

[0069] (1) Preparation of the first precursor

[0070] Weigh 5.83 g of copper chloride, dissolve it with 6.2 g of deionized water, and after complete dissolution, spray the obtained solution onto 20 g of alumina carrier to obtain precursor 1; use a muffle furnace to calcine precursor 1 at 300 °C for 5 hours to obtain precursor 2 (i.e., the first precursor). Among them, the surface area of the carrier is 200 m 2 / g, and the pore volume is 0.5 mL / g.

[0071] (2) Coating the second precursor on the first precursor

[0072] Weigh 67.2 g of pseudo-boehmite, peptize it with 8.6 g of dilute nitric acid solution (concentration: 10 wt%), add 275 g of silica sol with a concentration of 20 wt%, and the precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 450 °C for 6 hours to obtain catalyst precursor 3.

[0073] Weigh 26.8 g of copper nitrate, 6.2 g of cerium chloride, 2.4 g of lanthanum nitrate, 4.7 g of neodymium nitrate, and 17.8 g of potassium chloride, and dissolve them in 30 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0074] Dry the above catalyst precursor 4 at 400 °C for 1 hour, thereby forming a second precursor that wraps the first precursor on the first precursor, and thus obtaining the finished catalyst.

[0075] In the obtained catalyst, the copper element in the first precursor accounts for 14 wt% of the carrier mass; the mass percentage of the copper element in the second precursor is 4.4 wt%;

[0076] Based on the total mass of the catalyst, the mass percentage of the copper element is 6 wt%, the mass percentage of the cerium element is 1.5 wt%, the mass percentage of the lanthanum element is 0.5 wt%, the mass percentage of the neodymium element is 1 wt%, the mass percentage of the potassium element is 6 wt%, and the mass percentage of the first precursor is 14.7 wt%; in the first precursor, the mass percentage of the carrier is 88%; in the second precursor, the mass percentage of the coating material is 79.4%, and the mass ratio of silicon to aluminum in the coating material is 1.08:1.

[0077] The specific surface area of the obtained catalyst is 165 m 2 / g; the pore volume is 0.39 mL / g.

[0078] 2). Catalyst performance test:

[0079] Using the above "catalyst performance test method", evaluate the catalyst activity. React at a reaction temperature of 360 °C. After reacting for 24 hours, the HCl conversion rate reaches 85.1%. After continuously operating for 4000 hours, the HCl conversion rate reaches 85.4%. After the reaction ends and the catalyst is removed, it is found that the catalyst does not agglomerate and has good fluidity.

[0080] Example 3

[0081] 1) Catalyst preparation:

[0082] (1) Preparation of the first precursor

[0083] Weigh 6.37 g of copper chloride and dissolve it in 35.63 g of deionized water. After complete dissolution, spray the obtained solution onto 50 g of an alumina-silica support to obtain precursor 1. Use a muffle furnace to calcine precursor 1 at 300 °C for 5 hours to obtain precursor 2 (i.e., the first precursor). Among them, the silicon / aluminum mass ratio in the alumina-silica support is 0.2:1, the surface area of the support is 200 m 2 / g, and the pore volume is 0.7 mL / g.

[0084] (2) Coating the second precursor on the first precursor

[0085] Weigh 104.5 g of pseudoboehmite, peptize it with 13.4 g of dilute nitric acid solution (concentration: 10 wt%), add 150 g of silica sol with a concentration of 20 wt%, and the precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 600 °C for 3 hours to obtain catalyst precursor 3.

[0086] Weigh 14.5 g of copper nitrate, 28.9 g of cerium nitrate, 22.6 g of lanthanum nitrate, 20.6 g of neodymium chloride, and 19.8 g of potassium chloride, and dissolve them in 45.7 g of water. After complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0087] Dry the above catalyst precursor 4 at 400 °C for 1 hour, thereby forming a second precursor that wraps the first precursor on the first precursor, and thus obtaining the finished catalyst.

[0088] In the obtained catalyst, the copper element in the first precursor accounts for 6 wt% of the support mass; the mass percentage of the copper element in the second precursor is 1.5 wt%;

[0089] Based on the total mass of the catalyst, the mass percentage of the copper element is 3 wt%, the mass percentage of the cerium element is 4.5 wt%, the mass percentage of the lanthanum element is 3.5 wt%, the mass percentage of the neodymium element is 4 wt%, the mass percentage of the potassium element is 5 wt%, and the mass percentage of the first precursor is 25.6 wt%; in the first precursor, the mass percentage of the support is 94.4 wt%; in the second precursor, the mass percentage of the coating material is 74.3 wt%, and the silicon / aluminum mass ratio in the coating material is 0.38:1.

[0090] The specific surface area of the obtained catalyst is 170 m 2 / g; the pore volume is 0.63 mL / g.

[0091] 2). Catalyst performance test:

[0092] Using the above “catalyst performance test method”, the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 85.8%. After continuous operation for 4000 hours, the HCl conversion rate reached 86.2%. After the reaction was completed, the catalyst was removed and it was found that the catalyst did not agglomerate and had good fluidity.

[0093] Example 4

[0094] 1) Catalyst preparation:

[0095] (1) Preparation of the first precursor

[0096] Weigh 6.37 g of copper chloride and dissolve it in 35.63 g of deionized water. After complete dissolution, spray the obtained solution onto 50 g of an alumina-silica carrier to obtain precursor 1. Use a muffle furnace to calcine precursor 1 at 300 °C for 5 hours to obtain precursor 2 (i.e., the first precursor). Among them, the silicon / aluminum mass ratio in the alumina-silica carrier is 0.2:1, the surface area of the carrier is 200 m2 / g, and the pore volume is 0.7 mL / g.

[0097] (2) Coating the second precursor on the first precursor

[0098] Weigh 350 g of aluminum sol (concentration 20 wt%) for peptization, and add 150 g of silicon sol with a concentration of 20 wt% and precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 600 °C for 3 hours to obtain catalyst precursor 3.

[0099] Weigh 14.5 g of copper nitrate, 28.9 g of cerium nitrate, 22.6 g of lanthanum nitrate, 20.6 g of neodymium chloride, and 19.8 g of potassium chloride, and dissolve them in 45.7 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0100] Dry the above catalyst precursor 4 at 400 °C for 1 hour, so as to form a second precursor that wraps the first precursor on the first precursor, and thus obtain the finished catalyst.

[0101] In the obtained catalyst, the copper element in the first precursor accounts for 6 wt% of the carrier mass; the mass percentage of the copper element in the second precursor is 1.5 wt%;

[0102] Based on the total mass of the catalyst, the mass percentage of copper element is 3 wt%, the mass percentage of cerium element is 4.5 wt%, the mass percentage of lanthanum element is 3.5 wt%, the mass percentage of neodymium element is 4 wt%, the mass percentage of potassium element is 5 wt%, and the mass percentage of the first precursor is 25.6 wt%; in the first precursor, the mass percentage of the carrier is 94.4 wt%; in the second precursor, the mass percentage of the wrapping material is 74.3 wt%, and the mass ratio of silicon to aluminum in the wrapping material is 0.38:1.

[0103] The specific surface area of the obtained catalyst is 170 m2 / g; the pore volume is 0.47 mL / g.

[0104] 2). Catalyst performance test:

[0105] Using the above "catalyst performance test method", the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 81.2%. After continuous operation for 4000 hours, the HCl conversion rate reached 80.9%. After the reaction ended, the catalyst was removed and it was found that the catalyst did not agglomerate and had good fluidity.

[0106] Comparative Example 1

[0107] 1) Catalyst preparation:

[0108] (1) Weigh 29.2 g of copper nitrate, 5.2 g of cerium chloride, 2 g of lanthanum nitrate, 3.9 g of neodymium nitrate, and 14.8 g of potassium chloride, and dissolve them in 40 g of water; after complete dissolution, spray the above solution onto 100 g of an alumina-silica carrier. Among them, the silicon / aluminum mass ratio in the alumina-silica carrier is 0.05:1, the specific surface area of the carrier is 200 m 2 / g, and the pore volume is 0.5 mL / g.

[0109] (2) Calcine the above catalyst precursor at 400 °C for 1 hour to obtain the finished catalyst.

[0110] Based on the total mass of the catalyst, the mass percentage of copper element is 6 wt%, the mass percentage of cerium element is 1.5 wt%, the mass percentage of lanthanum element is 0.5 wt%, the mass percentage of neodymium element is 1 wt%, and the mass percentage of potassium element is 6 wt%.

[0111] 2) Catalyst performance test:

[0112] Using the above "catalyst performance test method", the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 85.2%. After running for 4000 hours, the HCl conversion rate reached 77.5%. After the reaction ended, the catalyst was removed and it was found that the catalyst agglomerated significantly, and the characterization results showed that.

[0113] Comparative Example 2

[0114] 1) Catalyst preparation:

[0115] (1) Preparation of the first precursor

[0116] Weigh 12.3 g of copper chloride and dissolve it in 29.7 g of deionized water. After complete dissolution, spray the obtained solution onto 50 g of an alumina-silica carrier to obtain precursor 1. Use a muffle furnace to calcine precursor 1 at 300 °C for 5 hours to obtain precursor 2 (i.e., the first precursor). Among them, the silicon / aluminum mass ratio in the alumina-silica carrier is 0.2:1, the surface area of the carrier is 200 m 2 / g, and the pore volume is 0.7 mL / g.

[0117] (2) Coating the second precursor on the first precursor

[0118] Weigh 104.5 g of pseudoboehmite and peptize it with 13.4 g of a dilute nitric acid solution (concentration 10 wt%) and add 150 g of a 20 wt% silica sol and precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 600 °C for 3 hours to obtain catalyst precursor 3.

[0119] Weigh 6.08 g of copper nitrate, 28.9 g of cerium nitrate, 22.6 g of lanthanum nitrate, 20.6 g of neodymium chloride, and 19.8 g of potassium chloride, and dissolve them in 54 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0120] Dry the above catalyst precursor 4 at 400 °C for 1 hour, thereby forming a second precursor on the first precursor that wraps the first precursor, and thus obtaining the finished catalyst.

[0121] In the obtained catalyst, the copper element in the first precursor accounts for 8.5 wt% of the carrier mass; the mass percentage of the copper element in the second precursor is 0.25 wt%;

[0122] Based on the total mass of the catalyst, the mass percentage of the copper element is 3 wt%, the mass percentage of the cerium element is 4.5 wt%, the mass percentage of the lanthanum element is 3.5 wt%, the mass percentage of the neodymium element is 4 wt%, the mass percentage of the potassium element is 5 wt%, and the mass percentage of the first precursor is 26.9 wt%; in the first precursor, the mass percentage of the carrier is 89.7 wt%; in the second precursor, the mass percentage of the coating material is 75.8 wt%.

[0123] The specific surface area of the obtained catalyst is 173 m 2 / g; the pore volume is 0.63 mL / g.

[0124] 2). Catalyst performance test:

[0125] Using the above "catalyst performance test method", the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 80.2%. After continuous operation for 4000 hours, the HCl conversion rate reached 79.6%. After the reaction, the catalyst caked.

[0126] Comparative Example 3

[0127] 1) Catalyst preparation:

[0128] (1) Preparation of the first precursor

[0129] Weigh 63.4 g of copper chloride and dissolve it in 240 g of deionized water. After complete dissolution, spray the obtained solution onto 300 g of alumina-silica support to obtain precursor 1. Use a muffle furnace to calcine precursor 1 at 450 °C for 2 hours to obtain precursor 2 (i.e., the first precursor). Among them, the silicon / aluminum mass ratio in the alumina-silica support is 0.05:1, the specific surface area of the support is 240 m 2 / g, and the pore volume is 0.85 mL / g.

[0130] (2) Coating the second precursor on the first precursor

[0131] Weigh 67.2 g of pseudo-boehmite and peptize it with 8.6 g of dilute nitric acid solution (concentration: 10 wt%), and add 325 g of silica sol with a concentration of 20 wt% and precursor 2 obtained in the above step (1). After stirring evenly, spray-dry the above slurry, and then calcine it at 600 °C for 3 hours to obtain catalyst precursor 3.

[0132] Weigh 70.6 g of copper nitrate, 72.2 g of cerium nitrate, 19.7 g of lanthanum chloride, 31.5 g of neodymium nitrate, and 11.6 g of sodium chloride, and dissolve them in 240 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0133] Dry the above catalyst precursor 4 at 200 °C for 4 hours, thereby coating the second precursor on the first precursor and obtaining the finished catalyst.

[0134] In the obtained catalyst, the mass percentage of copper element in the first precursor is 10%; the mass percentage of copper element in the second precursor is 2.8%;

[0135] Based on the total mass of the catalyst, the mass percentage of copper element is 8.2 wt%, the mass percentage of cerium element is 4.5 wt%, the mass percentage of lanthanum element is 1.5 wt%, the mass percentage of neodymium element is 2 wt%, the mass percentage of potassium element is 1.5 wt%, and the mass percentage of the first precursor is 63.7 wt%; in the first precursor, the mass percentage of the carrier is 91 wt%; in the second precursor, the mass percentage of the encapsulated material is 84 wt%.

[0136] The specific surface area of the obtained catalyst is 195 m 2 / g; the pore volume is 0.73 mL / g.

[0137] 2). Catalyst performance test:

[0138] Using the above "catalyst performance test method", the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 86.3%. After continuous operation for 4000 hours, the HCl conversion rate reached 77.5%. After the reaction, the catalyst did not agglomerate.

[0139] Comparative Example 4

[0140] 1). Catalyst preparation:

[0141] (1) Preparation of the first precursor

[0142] Weigh 5.83 g of copper chloride and dissolve it with 6.2 g of deionized water. After complete dissolution, spray the obtained solution onto 20 g of alumina carrier to obtain precursor 1; use a muffle furnace to calcine precursor 1 at 300 °C for 5 hours to obtain precursor 2 (i.e., the first precursor). Among them, the surface area of the carrier is 200 m 2 / g, and the pore volume is 0.5 mL / g.

[0143] (2) Encapsulating the second precursor on the first precursor

[0144] Add the precursor 2 obtained in the above step (1) to 500 g of silica sol with a concentration of 20 wt%. After stirring evenly, spray-dry the above slurry, and then calcine it at 450 °C for 6 hours to obtain catalyst precursor 3.

[0145] Weigh 26.9 g of copper nitrate, 6.2 g of cerium chloride, 2.4 g of lanthanum nitrate, 4.7 g of neodymium nitrate, and 17.8 g of potassium chloride, and dissolve them in 30 g of water; after complete dissolution, spray the above solution onto the above catalyst precursor 3 to obtain precursor 4.

[0146] Dry the above catalyst precursor 4 at 400 °C for 1 hour, thereby forming a second precursor on the first precursor to encapsulate the first precursor, and thus obtaining the finished catalyst.

[0147] In the obtained catalyst, the copper element in the first precursor accounts for 14% of the mass of the carrier; the mass percentage of the copper element in the second precursor is 4.4%;

[0148] Based on the total mass of the catalyst, the mass percentage of the copper element is 6 wt%, the mass percentage of the cerium element is 1.5 wt%, the mass percentage of the lanthanum element is 0.5 wt%, the mass percentage of the neodymium element is 1 wt%, the mass percentage of the potassium element is 6 wt%, and the mass percentage of the first precursor is 14.7 wt%; in the first precursor, the mass percentage of the carrier is 88%; in the second precursor, the mass percentage of the encapsulated material is 79.4%.

[0149] The specific surface area of the obtained catalyst is 165 m 2 / g; the pore volume is 0.35 mL / g.

[0150] 2). Catalyst performance test:

[0151] Using the above "catalyst performance test method", the activity of the catalyst was evaluated. The reaction was carried out at a reaction temperature of 360 °C. After 24 hours of reaction, the HCl conversion rate reached 85.7%. After continuous operation for 4000 hours, the HCl conversion rate reached 78.5%. After the reaction ended, the catalyst was removed and it was found that the catalyst caked.

[0152] It is easy to understand that the above embodiments are merely examples given for clear illustration and do not mean that the present invention is only limited thereto. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A catalyst for the catalytic oxidation of hydrogen chloride to chlorine, characterized in that, The catalyst includes a first precursor and a second precursor that wraps the first precursor; based on the total mass of the catalyst, the mass percentage of the first precursor is 10 - 60%; The first precursor includes a carrier, and the carrier is selected from alumina or a composition of alumina and silica; The second precursor includes a wrapping material that wraps the first precursor; the wrapping material is a composition of alumina and silica, and the mass ratio of silicon to aluminum in the wrapping material is 0.3 - 1.5:1; The active components are respectively loaded on the carrier and the wrapping material, and the active components include copper element, alkali metal element and rare earth element; The mass of copper element in the first precursor accounts for 4 - 18% of the mass of the first precursor; The mass of copper element in the second precursor accounts for 1 - 6% of the mass of the second precursor.

2. The catalyst according to claim 1, characterized in that, Based on the total mass of the catalyst, the mass percentage of the copper element is 1 - 15%.

3. The catalyst according to claim 1, characterized in that, Based on the total mass of the catalyst, the mass percentage of the copper element is 1.5 - 13 wt%.

4. The catalyst according to claim 3, characterized in that, Based on the total mass of the catalyst, the mass percentage of the copper element is 2 - 10 wt%.

5. The catalyst according to claim 2, wherein The alkali metal element is selected from one or both of potassium and sodium, and the rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium and samarium; Based on the total mass of the catalyst, the mass percentage of the alkali metal element is 0.1 - 8 wt%; the mass percentage of the rare earth element is 1.5 - 15 wt%.

6. The catalyst according to claim 5, characterized in that, Based on the total mass of the catalyst, the mass percentage of the alkali metal element is 1 - 7.5 wt%; the mass percentage of the rare earth element is 2 - 14 wt%.

7. The catalyst according to claim 6, characterized in that, Based on the total mass of the catalyst, the mass percentage of the alkali metal element is 1.2 - 7 wt%; the mass percentage of the rare earth element is 2.5 - 13.5 wt%.

8. The catalyst according to any one of claims 1 - 7, wherein In the first precursor, the mass percentage of the carrier is 77 - 97%; In the second precursor, the mass percentage of the wrapping material is 70 - 90%.

9. The catalyst according to any one of claims 1-7, characterized in that, The carrier is selected from a composition of alumina and silica, and the Si / Al mass ratio of silica to alumina in the carrier is 0.001 - 0.3:

1.

10. The catalyst according to any one of claims 1-7, characterized in that, The specific surface area of the catalyst is 50 to 300 m 2 / g; the pore volume is 0.1 to 0.9 mL / g.

11. The catalyst according to claim 10, wherein The specific surface area of the catalyst is 70-280 m 2 / g; the pore volume is 0.13-0.85 mL / g.

12. A method for preparing a catalyst according to any one of claims 1-11, characterized in that, It includes the following steps: 1) Impregnate the carrier with an aqueous solution containing a first soluble salt, and obtain the first precursor through calcination. The first soluble salt includes a soluble copper salt; 2) Contact the first precursor obtained in step 1) with the wrapping raw material and make the wrapping raw material wrap the first precursor, and obtain the first precursor wrapped with the wrapping material through drying and calcination; Then impregnate the first precursor wrapped with the wrapping material with an aqueous solution containing a second soluble salt, and obtain the catalyst with the second precursor wrapped on the first precursor through drying. The second soluble salt includes a soluble copper salt.

13. The method according to claim 12, wherein In step 1), the carrier is selected from one or more combinations of alumina, silica and titanium oxide; And / or, in step 2), the wrapping raw material includes a sol containing aluminum element; And / or, in step 2), the second soluble salt further includes soluble salts of alkali metal elements and soluble salts of rare earth elements; the alkali metal element is selected from one or two of potassium and sodium, and the rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium, and samarium.

14. The method according to claim 13, wherein In step 1), the carrier is selected from a composition of alumina and silica, and the Si / Al mass ratio of silica to alumina in the carrier is 0.001 - 0.3:1; And / or, in step 2), the coating raw material is a composition of a sol containing aluminum element and a sol containing silicon element; And / or, the first soluble salt does not include soluble salts of alkali metal elements and soluble salts of rare earth elements.

15. The method according to claim 13, characterized in that, The specific surface area of the carrier is 100 to 300 m 2 / g, and the pore volume is 0.1 to 0.95 mL / g; And / or, in step 2), the sol containing aluminum element is obtained by peptizing pseudoboehmite with a dilute acid aqueous solution having a concentration of 3 - 12 wt%, and the amount of the dilute acid aqueous solution used is 3 - 12% of the mass of the pseudoboehmite.

16. The method according to claim 15, wherein The specific surface area of the carrier is 120 - 280 m2 / g, and the pore volume is 0.15 - 0.92 mL / g.

17. The method according to any one of claims 12 - 16, characterized in that, In step 1), the conditions for roasting include: roasting temperature 200 - 660 °C; roasting time is 0.5 h - 8 h; And / or, in step 2), the conditions for roasting include: roasting temperature 300 - 700 °C; roasting time is 0.5 h - 10 h; And / or, in step 2), the conditions for drying after the impregnation include: drying temperature 90 - 500 °C; drying time is 0.5 h - 6 h.

18. The method according to claim 17, wherein In step 1), the roasting temperature is 260 - 500 °C, and the roasting time is 1 h - 6 h; And / or, in step 2), the roasting temperature is 350 - 650 °C, and the roasting time is 1 h - 8 h; And / or, in step 2), the drying temperature is 100 - 450 °C, and the drying time is 1 h - 4 h.

19. A method for preparing chlorine gas by hydrochloric acid oxidation, characterized in that, The chlorine gas is prepared by oxidizing hydrogen chloride in the presence of a catalyst, and the catalyst is the catalyst according to any one of claims 1 - 11 or the catalyst prepared by the method according to any one of claims 12 - 18.