A catalyst for producing chlorine, a production method thereof, and use thereof

Abstract

The application relates to a catalyst for preparing chlorine and application thereof. The catalyst is a structure in which an active component is coated with inorganic nonmetallic materials by doping with thallium; the catalyst has high conversion rate and good stability in the reaction of preparing chlorine by oxidizing hydrogen chloride, and the problems of poor wear resistance of the catalyst used in the fluidized bed reaction process, easy falling and pulverization of the active component during long-period operation, and reduction of the activity of the catalyst are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of catalysts, and particularly relates to a catalyst for preparing chlorine gas and application thereof. BACKGROUND

[0002] Chlorine is an important chemical raw material, which is widely used in many fields such as textiles, pharmaceuticals, petrochemical industry, drinking water disinfection and environmental protection industry. When chlorine is used for chemical synthesis, the utilization rate of chlorine atoms in most chlorine reactions is low, resulting in a large amount of chlorine resource loss. According to relevant literature statistics, with the development of China's chemical industry, the total amount of by-product hydrogen chloride has exceeded 5 million tons per year, along with the expansion of the production scale of products such as polyvinyl chloride, MDI, TDI, methane chloride and trichloroethylene. Taking toluene-2,4-diisocyanate (TDI) as an example, the generation of 1 molecule of TDI will be accompanied by the generation of 4 molecules of by-product hydrogen chloride: CH3C6H3(NH2)2+2COCl2 CH3C6H3(NCO)2+4HCl. The utilization rate of chlorine atoms is zero, and all chlorine atoms are converted into hydrogen chloride by-products. Due to the limited market of hydrogen chloride, small demand, and high environmental cost and end-of-pipe treatment cost, if not fully recycled and utilized, it is not conducive to the development of green chemistry. Therefore, people urgently hope to find an economically suitable hydrogen chloride preparation process to realize the closed-loop circulation and zero emission of chlorine elements, and this research is of great significance.

[0003] As early as the nineteenth century, foreign researchers have begun to study the hydrogen chloride preparation process. So far, there are mainly three methods: electrolysis method, direct oxidation method and catalytic oxidation method. Among them, the catalytic oxidation method with low energy consumption and simple operation is favored by the relevant industry and has become a research hotspot in recent years. The catalytic oxidation method is to convert HCl into Cl2 under the action of a catalyst with O2 as the oxidant, and the reaction formula is as follows:

[0004] 4HCl+O2→2H2O+2Cl2

[0005] The reaction is a reversible reaction, which is subject to equilibrium, and the reaction temperature is relatively high, so the requirements for the catalyst are relatively harsh. How to obtain a catalyst with high activity and high stability has always been the core of research in this field. The catalysts used in the hydrogen chloride catalytic oxidation method for preparing chlorine gas mainly include copper-based, chromium-based and ruthenium-based catalysts, as well as cerium-based catalysts developed in recent years. Among them, the copper-based catalyst has excellent activity, low cost and easy regeneration, and has broad industrial application prospects, so researchers have carried out extensive and in-depth research on it.

[0006] Patent CN201610625612.9 adds B, Nb, P and other elements as copper-based catalyst additives, the addition of B element greatly slows down the loss of Cu component, prolongs the service life of the catalyst, and good catalytic performance is obtained, but the hydrogen chloride conversion rate is only 80%.

[0007] In patent CN201711220899.8, the active component of the catalyst is a ruthenium component, the active component is treated by hydrogen peroxide to prepare the catalyst, the hydrogen chloride conversion rate is only 35.9%, and a noble metal ruthenium element is used.

[0008] Chinese patent CN101559374 discloses a catalyst using silica gel and ReY molecular sieve as carriers, and loading copper chloride, potassium chloride, manganese nitrate and cerium nitrate, under the conditions that the hydrogen chloride and oxygen flow rates are both 200 ml / min, the catalyst dosage is 25 g, and the reaction temperature is 380℃, the hydrogen chloride conversion rate is 83.6%. However, the catalyst also has the disadvantages of copper component loss and low space velocity. SUMMARY

[0009] In order to overcome the problems of poor stability and low catalytic activity of the copper-based catalyst in the prior art, the application provides a catalyst for preparing chlorine gas and application thereof. The catalyst overcomes the shortcomings of the existing copper-based catalyst, and thallium is added in the copper-based catalyst and the catalyst is prepared in the form of inorganic non-metallic material coating the active component, so that the catalyst has the advantages of high activity, good stability and wear resistance.

[0010] To solve the above technical problems, on the one hand, the application provides a catalyst for preparing chlorine gas, which comprises a carrier, an inorganic non-metallic material and an active component, and the composition of the active component contained in the catalyst is represented by the following general formula (1):

[0011] Cu a Tl b X c Y d Z e C f O g (1)

[0012] In the formula, X is selected from one of alkali metals; Y is selected from at least one of transition metals or alkaline earth metals manganese, iron, nickel, cobalt, zinc, titanium, magnesium, calcium and barium; and Z is selected from one of rare earth elements;

[0013] The value range of a is 0.3-1.2, preferably 0.3-0.6

[0014] The value range of b is 0.01-0.2, preferably 0.03-0.2

[0015] c is in the range of 0.1-0.8, preferably 0.1-0.6;

[0016] d is in the range of 0.1-0.8, preferably 0.1-0.4;

[0017] e is in the range of 0.01-0.3, preferably 0.01-0.1;

[0018] f is in the range of 1-2.8, preferably 1-2.5;

[0019] g is the number of oxygen atoms required to satisfy the valence of each element in the catalyst;

[0020] Preferably, the active component is Cu 0.3～0.6 Tl 0.03～0.2 X 0.1～0.6 Y 0.10～0.4 Z 0.01～0.1 C 1～2.5 O g g is the number of oxygen atoms required to satisfy the valence of each element in the catalyst;

[0021] The carrier, inorganic non-metallic material and active component are used in the amount of 3-15:0.01-0.2:10-25, based on the total weight of the catalyst.

[0022] The alkali metal is one of lithium, sodium, potassium and cesium, preferably sodium or potassium. The rare earth element is at least one of the lanthanide series, preferably cerium, lanthanum, praseodymium and neodymium.

[0023] The carrier is one or more of molecular sieve, kaolin, diatomite, silicon dioxide, aluminum oxide, titanium dioxide and zirconium dioxide, preferably molecular sieve or kaolin, and the molecular sieve is more preferably Y-type molecular sieve.

[0024] In another aspect, the present application provides a method for preparing a catalyst for producing chlorine gas, comprising the following steps: 1) dissolving the required copper compound, thallium compound, transition metal compound, alkali metal compound, alkaline earth metal compound and rare earth metal compound in water, impregnating with the carrier, drying, and calcining to obtain a catalyst precursor; 2) adding the catalyst precursor in step 1) to a hydrogen peroxide solution, then stirring, filtering and drying to obtain a preliminary catalyst; 3) adding inorganic carbon material and binder to a rotary roll coater respectively, and coating the inorganic carbon material on the surface of the preliminary catalyst by adjusting the spraying speed of the binder in the rotary roll coater to obtain an intermediate catalyst; and then washing the intermediate catalyst with alkali, acid and water successively, and drying and calcining to obtain a catalyst for producing chlorine gas.

[0025] The copper-containing compound in the step 1) is a soluble salt of copper, preferably one or more of copper nitrate, copper chloride and copper acetate, more preferably copper nitrate and copper chloride. Generally, when two or more are used, there is no limitation on the ratio, and they can be combined in any ratio;

[0026] The transition metal-containing compound in the step 1) is one or more of soluble salts of manganese, iron, nickel, cobalt, zinc, titanium, preferably one or more of nitrate, chloride or acetate of manganese, iron, nickel, cobalt, zinc, titanium, more preferably one or more of nitrate, chloride or acetate of manganese, iron, cobalt, zinc;

[0027] The thallium-containing compound in the step 1) is di-thallium trioxide;

[0028] The alkali metal compound in the step 1) is one or more of chloride, nitrate, acetate, carbonate or borate of lithium, sodium or potassium, preferably chloride, nitrate, acetate, carbonate or borate of sodium or potassium;

[0029] The alkaline earth metal compound in the step 1) is one or more of chloride, nitrate, acetate, carbonate or borate of magnesium, calcium or barium, preferably chloride, nitrate, acetate, carbonate or borate of magnesium or calcium;

[0030] The rare earth metal compound in the step 1) is nitrate or chloride salt of cerium, lanthanum, praseodymium and neodymium, preferably nitrate;

[0031] The amount of each compound in the step 1) is not particularly limited, as long as it can satisfy the ratio of the compound represented by the general formula (1).

[0032] The drying temperature in the step 1) is 60-100°C, preferably 80-100°C, the calcination temperature is 500-600°C, preferably 500-550°C, and the time is 10-15h, preferably 10-12h;

[0033] The mass ratio of the catalyst precursor to the hydrogen peroxide solution in the step 2) is 1:1-1.5, and the concentration of the hydrogen peroxide solution is 20-40wt%, preferably 25-36wt%.

[0034] The stirring temperature in the step 2) is 40-80°C, preferably 45-75°C, and the stirring time is 3-8h, preferably 4-7h;

[0035] The filtration process in the step 2) is selected from reduced pressure filtration, and the drying temperature is 30-60°C, preferably 50-60°C,

[0036] In step 3), the inorganic carbon material is selected from one or more of carbon nanofibers, carbon nanotubes, carbon quantum dots, carbon nanosheets and graphene, with carbon nanofibers being preferred, and carbon nanofibers with an outer diameter of 200-600 nm and a length of 5-50 μm being even more preferred.

[0037] In step 3), the binder is selected from ethanol, water, and methanol, with ethanol being preferred.

[0038] In step 3), the mass ratio of inorganic carbon material, binder, and initial catalyst is 1.0–2.5: 0.55–0.95: 15–25.

[0039] In step 3), the specific reagent for alkaline washing is selected from NaOH, the reagent for acid washing is selected from an aqueous solution of sulfuric acid and nitric acid in a mass ratio of 1:1, the drying temperature is 40-100℃, preferably 80-100℃, the calcination temperature is 450-550℃, and the time is 3h.

[0040] In addition, the present invention also provides the application of a catalyst in the catalytic oxidation of hydrogen chloride to chlorine.

[0041] Finally, the present invention provides a method for the catalytic oxidation of hydrogen chloride to chlorine, the method comprising the following steps: the catalyst of the present invention is applied to the reaction for the catalytic oxidation of hydrogen chloride to chlorine in a fluidized bed reactor. The reaction conditions are: reaction temperature of 320–460°C, preferably 360–400°C; reaction pressure of 0.1–0.6 MPa, preferably 0.1–0.35 MPa; molar ratio of hydrogen chloride to oxygen of 0.5–9:1, preferably 1–4:1; and mass hourly space velocity of hydrogen chloride of 0.1–2.5 h⁻¹. -1 Preferably 0.5 to 2 hours -1 .

[0042] The reaction products were absorbed with excess potassium iodide solution, and the chlorine gas produced was determined by iodometric titration. Unreacted hydrogen chloride was obtained by acid-base titration, and the yield of chlorine gas was calculated accordingly.

[0043] The solution of the present invention has the following advantages:

[0044] The catalyst provided by this invention has the advantages of simple preparation process and relatively low price compared with gold and ruthenium catalysts.

[0045] The catalyst in the application belongs to copper-based catalyst, and the surface oxygen property of the catalyst has great relation with the catalytic reaction performance. The active oxygen species need to be provided to the reaction site, and only the high-efficiency cooperation between the active oxygen species and the reactant can greatly improve the catalytic activity and selectivity. In the reaction, the hydrogen chloride molecules are oxidized into the target product by the lattice oxygen on the surface of the catalyst. After the lattice oxygen participates in the reaction, the gas-phase oxygen is adsorbed and oxidized to the initial state by the low-valence oxide in the active component of the catalyst, and the RedoS oxidation-reduction mode is completed. Therefore, the lattice oxygen plays a leading role in the reaction, and the adsorbed oxygen plays a synergistic role. The introduction of thallium element and the treatment by hydrogen peroxide are beneficial to the desorption of chloride ions from the surface of the catalyst, reduce the oxidation of the chloride ions by the lattice oxygen, and thus achieve the purpose of inhibiting deep oxidation.

[0046] By adopting the form of inorganic non-metallic material coating, the problem of activity reduction caused by the mutual abrasion of the catalyst in the fluidized bed and the falling of the active component is reduced. At the same time, the catalyst is subjected to alkali washing and acid etching to form pores on the surface of the catalyst, increase the oxygen vacancies, and provide the material basis and place for the rapid bulk phase migration of the lattice oxygen ions, so as to ensure that the reaction proceeds in the direction of high selectivity and enhance the service life of the catalyst. DETAILED DESCRIPTION

[0047] The application will be further described by examples, but is by no means limited to the following examples.

[0048] Raw materials and sources:

[0049] Copper chloride, dihydrate: Aladdin; brand: C111685; specification: purity 99.999%;

[0050] Sodium chloride: Aladdin; brand: C111544; specification: purity 99.999%;

[0051] Cerium nitrate, hexahydrate: Aladdin; brand: C105378; specification: purity 99.95%;

[0052] Neodymium nitrate, hexahydrate: Aladdin; brand: N119418; specification: purity 99.9%;

[0053] Magnesium nitrate, hexahydrate: Nan test; brand: C0190530223; specification: purity 99%;

[0054] Carbon nanofiber: Super color industry; brand: C308068; specification: purity 99%;

[0055] Sodium hydroxide: Aladdin; brand: S111498; specification: purity 96%.

[0056] Hydrogen peroxide: Aladdin; brand: H414630; specification: 30wt%;

[0057] Ethanol: Aladdin; brand: E111946; specification: 99.8%;

[0058] Test method: The reaction product is absorbed with excess potassium iodide solution, the reaction generated chlorine is determined by iodine method, and the unreacted hydrogen chloride is obtained by acid-base titration, so as to calculate the yield of chlorine.

[0059] Example 1

[0060] Take 51g CuCl2·2H2O, 9.13g Tl2O3, 5.8g NaCl, 21.7g Ce(NO3)3·6H2O, 21.9g Nd(NO3)3·6H2O, 25.6g Mg(NO3)2·6H2O in 50ml water in turn, and stir well to form a slurry. Then add 200g HY molecular sieve and stir at 70℃ for 6h, after sufficient impregnation, the catalyst is placed in an oven, dried at 100℃ for 8h, then taken out and placed in a calcination furnace, calcined at 550℃ for 12h, and taken out after natural cooling to obtain the catalyst precursor. The catalyst precursor is added to hydrogen peroxide with an equal mass concentration of 30wt%, stirred at 60℃ for 5h, then filtered and dried at 100℃ for 7h to obtain the initial catalyst. Then take 1g carbon nanofiber and the initial catalyst in the rotary rolling machine to realize the rotary coating of the carbon nanofiber on the outer surface of the initial catalyst by adjusting the ethanol spraying speed. After shaping, dry at 100℃ for 5h to obtain the intermediate catalyst. Then the intermediate catalyst is added to a three-necked flask containing 1000g of 50wt% sodium hydroxide aqueous solution. The above slurry is refluxed and stirred at 90℃ for 5h for alkali modification. After alkali modification, the intermediate catalyst is filtered and washed with deionized water until the filtrate pH is 6-8. After washing is completed, the intermediate catalyst is subjected to acid modification. The above intermediate catalyst is added to a three-necked flask containing 1000g of 50wt% sulfuric acid and nitric acid aqueous solution with a mass ratio of 1:1. The above slurry is refluxed and stirred at 90℃ for 5h for acid modification. After acid modification, the catalyst is filtered and washed with deionized water until the filtrate pH is 6-8. Dry in an oven at 100℃, and calcine at 550℃ for 3h to obtain 293g of active catalyst. Press into 30-60 mesh catalyst particles.

[0061] Put 6g of 30-60 mesh catalyst into a fixed bed reactor, and react under the conditions of hydrogen chloride and oxygen flow rate of 100ml / min, reaction temperature of 380℃, and reaction pressure of 0.18Mpa. The chlorine yield after 4h of reaction is 89.2%, and the chlorine yield after 100h of reaction is 88.9%, and the catalyst activity remains stable.

[0062] Example 2

[0063] Example 2 85g CuCl2.2H2O, 27.4g Tl2O3, 11.7g NaCl, 34.72g Ce(NO3)3.6H2O, 35.04g Nd(NO3)3.6H2O, 51.2g Mg(NO3)2.6H2O were weighed in sequence and dissolved in 50ml water, and stirred to form a slurry. Then 200g HY molecular sieve was added and stirred at 70°C for 6h. After sufficient impregnation, the catalyst was placed in an oven and dried at 100°C for 8h, and then placed in a calcination furnace and calcined at 550°C for 12h. After natural cooling, the catalyst precursor was obtained. The catalyst precursor was added to hydrogen peroxide with an equal mass concentration of 30wt%, and stirred at 60°C for 5h. After filtration and drying at 100°C for 7h, the initial catalyst was obtained. Then 2g carbon nanofiber was weighed and coated on the outer surface of the initial catalyst in a rotary coating machine by adjusting the ethanol spray speed. After shaping and drying at 100°C for 5h, the intermediate catalyst was obtained. Then the intermediate catalyst was added to a three-necked flask containing 1000g of 50wt% sodium hydroxide aqueous solution. The slurry was refluxed and stirred at 90°C for 5h for alkali modification. After alkali modification, the intermediate catalyst was filtered and washed with deionized water until the filtrate pH was 6-8. After washing was completed, the intermediate catalyst was subjected to acid modification. The intermediate catalyst was added to a three-necked flask containing 1000g of 50wt% sulfuric acid and nitric acid aqueous solution with a mass ratio of 1:1. The slurry was refluxed and stirred at 90°C for 5h for acid modification. After acid modification, the catalyst was filtered and washed with deionized water until the filtrate pH was 6-8. The catalyst was dried in an oven at 100°C, and calcined at 550°C for 3h to obtain 369g of active catalyst. The catalyst was pressed into 30-60 mesh catalyst particles.

[0064] 6g of 30-60 mesh catalyst was loaded into a fixed bed reactor and reacted under the conditions of hydrogen chloride and oxygen flow rates of 100ml / min, reaction temperature of 380°C, and reaction pressure of 0.18Mpa. The chlorine yield after 4h of reaction was 89.1%, and the chlorine yield after 100h of reaction was 89.6%, and the catalyst activity remained stable.

[0065] Example 3

[0066] 102g CuCl2·2H2O, 45.7g Tl2O3, 17.5g NaCl, 43.4g Ce(NO3)3·6H2O, 43.8g Nd(NO3)3·6H2O, and 102.4g Mg(NO3)2·6H2O were weighed out sequentially and dissolved in 50ml of water. The mixture was stirred thoroughly to form a slurry. Then, 200g HY molecular sieve was added and stirred at 70℃ for 6h to fully impregnate the catalyst. The catalyst was then placed in an oven and dried at 100℃ for 8h. After drying, the catalyst was placed in a calcination furnace and calcined at 550℃ for 12h. After natural cooling, the catalyst precursor was obtained. The catalyst was added to a 30wt% hydrogen peroxide solution, stirred at 60°C for 5 hours, filtered, and dried at 100°C for 7 hours to obtain an initial catalyst. Then, 2.5g of carbon nanofibers were weighed and coated onto the outer surface of the initial catalyst using a rotary coater by adjusting the ethanol spray rate. After shaping, the coating was dried at 100°C for 5 hours to obtain an intermediate catalyst. The intermediate catalyst was then added to a three-necked flask containing 1000g of a 50wt% sodium hydroxide aqueous solution. The slurry was refluxed and stirred at 90°C for 5 hours. Alkali modification was performed, followed by filtration of the intermediate-stage catalyst. The catalyst was washed with deionized water until the pH of the filtrate reached 6–8. After washing, the intermediate-stage catalyst underwent acid modification. The catalyst was added to a three-necked flask containing 1000g of a 1:1 (50wt%) aqueous solution of sulfuric acid and nitric acid. The slurry was refluxed and stirred at 90°C for 5 hours for acid modification. The catalyst obtained after acid modification was washed with deionized water until the pH of the filtrate reached 6–8. It was then dried in an oven at 100°C and calcined at 550°C for 3 hours to obtain 428g of active catalyst. The catalyst was then compressed into tablets to obtain 30–60 mesh catalyst particles.

[0067] 6g of 30-60 mesh catalyst was loaded into a fixed-bed reactor and reacted at a flow rate of 100ml / min for both hydrogen chloride and oxygen, a reaction temperature of 380℃, and a reaction pressure of 0.18MPa. The chlorine yield was 88.5% after 4 hours of reaction and 88.1% after 100 hours, indicating stable catalyst activity.

[0068] Example 4

[0069] Take 51 g CuCl2.2H2O, 9.13 g Tl2O3, 5.8 g NaCl, 21.8 g Pr(NO3)3.6H2O, 21.7 g La(NO3)3.6H2O, 25.6 g Mg(NO3)2.6H2O in 50 ml water, stir well to form slurry. Then add 200 g HY molecular sieve and stir at 70°C for 6 h, after sufficient impregnation, the catalyst is placed in an oven, dried at 100°C for 8 h, then placed in a calcination furnace, calcined at 550°C for 12 h, naturally cooled, then removed, to obtain the catalyst precursor. The catalyst precursor is added to hydrogen peroxide with an equal mass concentration of 30 wt%, stirred at 60°C for 5 h, then filtered and dried at 100°C for 7 h to obtain the initial catalyst, then take 1 g carbon nanofiber and the initial catalyst in the rotary roll coater to realize the rotary coating of the carbon nanofiber on the outer surface of the initial catalyst by adjusting the spraying speed of ethanol, after shaping, dry at 100°C for 5 h to obtain the intermediate catalyst, then add the intermediate catalyst to a three-necked flask containing 1000 g of 50 wt% sodium hydroxide aqueous solution, the above slurry is refluxed and stirred at 90°C for 5 h for alkali modification, after alkali modification, the intermediate catalyst is filtered and washed with deionized water until the filtrate pH is 6-8, after washing, the intermediate catalyst is acid modified, the above intermediate catalyst is added to a three-necked flask containing 1000 g of 50 wt% sulfuric acid and nitric acid aqueous solution with a mass ratio of 1:1, the above slurry is refluxed and stirred at 90°C for 5 h for acid modification, after acid modification, the catalyst is filtered and washed with deionized water until the filtrate pH is 6-8, dried in an oven at 100°C, and calcined at 550°C for 3 h to obtain the active catalyst 273 g. Pressed into 30-60 mesh catalyst particles.

[0070] 6 g of 30-60 mesh catalyst is loaded into a fixed bed reactor, and reacted under the conditions of hydrogen chloride and oxygen flow rate of 100 ml / min, reaction temperature of 380°C, and reaction pressure of 0.18 Mpa. The chlorine yield after 4 hours of reaction is 89.9%, and the chlorine yield after 100 hours of reaction is 88.6%, and the catalyst activity remains stable.

[0071] Example 5

[0072] Take 102 g of CuCl2.2H2O, 45.7 g of Tl2O3, 17.5 g of NaCl, 43.4 g of Ce(NO3)3.6H2O, 43.5 g of Pr(NO3)3.6H2O, 102.4 g of Mg(NO3)2.6H2O in 50 ml of water, and stir well to form a slurry. Then add 200 g of HY molecular sieve and stir at 70°C for 6 h. After sufficient impregnation, the catalyst is placed in an oven and dried at 100°C for 8 h, then placed in a calcination furnace and calcined at 550°C for 12 h, and then taken out after natural cooling. Add to hydrogen peroxide with an equal mass concentration of 30 wt%, stir at 60°C for 5 h, then filter and dry at 100°C for 7 h to obtain the initial catalyst. Then take 2.5 g of carbon nanofiber and coat it on the outer surface of the initial catalyst in a rotary rolling machine by adjusting the ethanol spray speed. After shaping, dry at 100°C for 5 h to obtain the intermediate catalyst. Then add the intermediate catalyst to a three-necked flask containing 1000 g of 50 wt% sodium hydroxide aqueous solution. Stir the slurry at 90°C for 5 h for alkali modification. After alkali modification, filter the intermediate catalyst and wash with deionized water until the filtrate pH is 6-8. After washing is complete, the intermediate catalyst is subjected to acid modification. Add the intermediate catalyst to a three-necked flask containing 1000 g of a 50 wt% sulfuric acid and nitric acid aqueous solution with a mass ratio of 1:1. Stir the slurry at 90°C for 5 h for acid modification. After acid modification, filter the catalyst and wash with deionized water until the filtrate pH is 6-8. Dry in an oven at 100°C, and calcine at 550°C for 3 h to obtain 372 g of active catalyst. Press into 30-60 mesh catalyst particles.

[0073] Put 6 g of 30-60 mesh catalyst into a fixed bed reactor and react under the conditions of hydrogen chloride and oxygen flow rates of 100 ml / min each, a reaction temperature of 380°C, and a reaction pressure of 0.18 Mpa. The chlorine yield after 4 hours of reaction is 88.5%, and the chlorine yield after 100 hours of reaction is 88.1%, with the catalyst activity remaining stable.

[0074] Comparative Example 1

[0075] Catalyst preparation according to Example 1: the only difference is that no thallium trioxide component is added during active component loading, and the other operations are the same as in Example 1. The chlorine yield after 4 hours of reaction is 86.1%, and the chlorine yield after 100 hours of reaction is 80.6%.

[0076] Comparative Example 2

[0077] Catalyst preparation according to Example 1: the only difference is that no carbon nanofiber is added, and the preparation operation is as follows:

[0078] Take 51 g of CuCl2.2H2O, 9.13 g of Tl2O3, 5.8 g of NaCl, 21.7 g of Ce(NO3)3.6H2O, 21.9 g of Nd(NO3)3.6H2O, 25.6 g of Mg(NO3)2.6H2O in 50 ml of water in turn, and stir well to form a slurry. Then add 200 g of HY molecular sieve and stir at 70°C for 6 h, and after sufficient impregnation, the catalyst is placed in an oven and dried at 100°C for 8 h, then taken out and placed in a calcination furnace, calcined at 550°C for 12 h, and after natural cooling, the catalyst precursor is obtained. Add to hydrogen peroxide with an equal mass concentration of 30wt%, stir at 60°C for 5 h, then filter and dry at 100°C for 7 h to obtain the initial catalyst, and calcine at 550°C for 3 h to obtain the active catalyst 292 g. Press into 30-60 mesh catalyst particles. Load 6 g of 30-60 mesh catalyst into a fixed bed reactor, and react under the conditions of hydrogen chloride and oxygen flow rates of 100 ml / min each, reaction temperature of 380°C, and reaction pressure of 0.18 Mpa. The chlorine yield after 4 h of reaction is 86.6%, and the chlorine yield after 100 h of reaction is 82.0%.

[0079] Comparative Example 3

[0080] Catalyst preparation according to Example 1: The difference is that no carbon nanofibers are added to the active component, and no acid washing and alkali washing are performed, and the preparation operation is as follows:

[0081] Take 102 g of CuCl2.2H2O, 45.7 g of Tl2O3, 17.5 g of NaCl, 43.4 g of Ce(NO3)3.6H2O, 43.8 g of Nd(NO3)3.6H2O, 102.4 g of Mg(NO3)2.6H2O in 50 ml of water in turn, and stir well to form a slurry. Then add 200 g of HY molecular sieve and stir at 70°C for 6 h, and after sufficient impregnation, the catalyst is placed in an oven and dried at 100°C for 8 h, then taken out and calcined at 550°C for 3 h to obtain the active catalyst 380 g. Press into 30-60 mesh catalyst particles. Load 6 g of 30-60 mesh catalyst into a fixed bed reactor, and react under the conditions of hydrogen chloride and oxygen flow rates of 100 ml / min each, reaction temperature of 380°C, and reaction pressure of 0.18 Mpa. The chlorine yield after 4 h of reaction is 83.6%, and the chlorine yield after 100 h of reaction is 80.0%.

[0082] It is found by comparing Example 1 and Comparative Example 1 that adding diarsenic trioxide to the active component and treating with hydrogen peroxide is beneficial to the desorption of chlorine ions from the surface of the catalyst, reduces the oxidation effect of lattice oxygen, thereby achieving the purpose of inhibiting deep oxidation, and improving the chlorine yield and activity.

[0083] By comparing example 3 with comparative examples 2 and 3, it is found that the catalyst prepared in the form of inorganic non-metallic material coating can reduce the problem of activity reduction caused by the mutual abrasion of catalysts in the fluidized bed, which leads to the shedding of active components. At the same time, the catalyst is subjected to alkaline washing and etching of the catalyst surface with acid to form pores, increase oxygen vacancies, and provide a material basis and place for the rapid bulk phase migration of lattice oxygen ions, which ensures the reaction to proceed in the direction of high selectivity and enhances the service life of the catalyst.

Claims

1. A catalyst for producing chlorine gas, the catalyst comprising a carrier, an inorganic carbon material and an active component, the catalyst comprising an active component whose composition is represented by the following general formula (1): XaYbZcMdOeOf (1) wherein: X is selected from one of alkali metals; Y is selected from at least one of transition metals or alkaline earth metals manganese, iron, nickel, cobalt, zinc, titanium, magnesium, calcium, barium; Z is selected from one of rare earth elements; a is in the range of 0.3 to 1.2; b is in the range of 0.01 to 0.2; c is in the range of 0.1 to 0.8; d is in the range of 0.1 to 0.8; e is in the range of 0.01 to 0.3; f is in the range of 1 to 2.8; g is the number of oxygen atoms required to satisfy the valence of each element of the catalyst. Cu a Tl b X c Y d Z e C f O g (1) 2) adding the catalyst precursor in step 1 to a hydrogen peroxide solution, then stirring, filtering and drying to obtain a preliminary catalyst; 3) adding the inorganic carbon material and the binder to a rotary roll coater respectively, and coating the inorganic carbon material on the surface of the preliminary catalyst in the rotary roll coater by adjusting the spraying speed of the binder to obtain an intermediate catalyst; drying and calcining the intermediate catalyst after sequentially passing through alkaline washing, acid washing and water washing to obtain the catalyst for producing chlorine gas. The carrier, the inorganic carbon material and the active component are used in an amount of 3-15:0.01-0.2:10-25 based on the total weight of the catalyst. The alkali metal is one of lithium, sodium, potassium and cesium; and the rare earth element is at least one of lanthanide elements. The rare earth element is cerium, lanthanum, praseodymium and neodymium. The carrier is one or more of molecular sieve, kaolin, diatomite, silicon dioxide, aluminum oxide, titanium dioxide and zirconium dioxide. The molecular sieve is Y-type molecular sieve. The preparation method of the catalyst comprises the following steps: 1) dissolving the required copper-containing compound, thallium-containing compound, transition metal compound, alkali metal compound, alkaline earth metal compound and rare earth metal compound in water, impregnating with a carrier, drying, calcining to obtain a catalyst precursor; The method comprises the following steps: 1) dissolving the required copper-containing compound, thallium-containing compound, transition metal compound, alkali metal compound, alkaline earth metal compound and rare earth metal compound in water, impregnating with the carrier, drying and calcining to obtain a catalyst precursor; 2) adding the catalyst precursor in step 1 to a hydrogen peroxide solution, then stirring, filtering and drying to obtain a preliminary catalyst; 3) adding the inorganic carbon material and the binder to a rotary roll coater respectively, and coating the inorganic carbon material on the surface of the preliminary catalyst in the rotary roll coater by adjusting the spraying speed of the binder to obtain an intermediate catalyst; 2. The catalyst of claim 1, wherein The active component is Cu 0.3～0.6 Tl 0.03～0.2 X 0.1～ 0.6 Y 0.10～0.4 Z 0.01～0.1 C 1～2.5 O g g is the number of oxygen atoms required to satisfy the valence of each element of the catalyst.

3. The catalyst of claim 1, wherein drying and calcining the intermediate catalyst after sequentially passing through alkaline washing, acid washing and water washing to obtain the catalyst for producing chlorine gas.

4. The catalyst of claim 1, wherein The copper-containing compound in step 1 is a soluble salt of copper; and / or, the transition metal-containing compound in step 1 is one or more of soluble salts of manganese, iron, nickel, cobalt, zinc and titanium; and / or, the thallium-containing compound in step 1 is di-thallium trioxide.

5. The catalyst of claim 4, wherein The copper-containing compound in step 1 is one or more of copper nitrate, copper chloride and copper acetate; and / or, the transition metal-containing compound in step 1 is one or more of nitrate, chloride or acetate of manganese, iron, nickel, cobalt, zinc and titanium.

6. The catalyst according to any one of claims 1 to 5, wherein ​ 7. The catalyst of claim 6, wherein ​ 8. The process for the preparation of a catalyst according to any one of claims 1 to 7, characterized in that, ​ ​ ​ ​ 9. The production method according to claim 8, wherein ​ 10. The production method according to claim 9, wherein ​ 11. The production method according to any one of claims 8 to 10, wherein The alkali metal compound in the step 1) is one or more of lithium, sodium, potassium chloride, nitrate, acetate, carbonate or borate; and / or, the alkaline earth metal compound in the step 1) is one or more of magnesium, calcium, barium chloride, nitrate, acetate, carbonate or borate; and / or, the rare earth metal compound in the step 1) is cerium, lanthanum, praseodymium and neodymium nitrate or chloride salt.

12. The production method according to any one of claims 8 to 10, wherein The temperature of the drying in the step 1) is 60-100℃, the temperature of the calcination is 500-600℃, and the time is 10-15h; and / or, the temperature of the stirring in the step 2) is 40-80℃, and the stirring time is 3-8h; and / or, the filtration process in the step 2) is selected from reduced pressure filtration, and the drying temperature is 30-60℃.

13. The production method according to any one of claims 8 to 10, wherein The inorganic carbon material in the step 3) is selected from one or more of carbon nanofiber, carbon nanotube, carbon quantum dot, carbon nanosheet and graphene; and / or, the mass ratio of the inorganic carbon material, the binder and the initial catalyst in the step 3) is 1.0-2.5: 0.55-0.95: 15-25.

14. The use of the catalyst of any one of claims 1-7 or the catalyst prepared by the preparation method of any one of claims 8-13 in the hydrogen chloride catalytic oxidation reaction for preparing chlorine.