A catalyst for preparing ethylene by oxidative dehydrogenation of ethane, a preparation method and application thereof

Abstract

The application provides a catalyst for preparing ethylene through oxidative dehydrogenation of ethane, the catalyst is a lanthanum-based perovskite catalyst and contains La x Sr 1‑x MO 3‑y Cl z ; wherein x is a positive number less than 1, M is Mn and / or Fe, y is a positive number less than 3, z is an arbitrary value in the range of 0.01-0.5, and the specific surface area of the catalyst is 25-50 m 2 / g. The application also provides a preparation method and application of the catalyst. Through the above technical scheme, the catalyst has a high specific surface area and a large pore volume, and can further improve the conversion rate and selectivity of ethylene prepared through oxidative dehydrogenation of ethane.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petroleum chemical industry, and particularly relates to a catalyst for preparing ethylene by dehydrogenation of ethane, preparation and application thereof. BACKGROUND

[0002] Ethylene is one of the largest chemical products in the world, and the ethylene industry is the core of the petrochemical industry and occupies an important position in the national economy. Ethylene production is one of the important symbols to measure the development level of a country's petrochemical industry. As a basic component of the petrochemical industry, light olefins (such as ethylene and propylene) can be used to produce polymers, oxides and various other valuable chemical products. At present, ethylene is mainly produced by steam cracking of ethane and naphtha. In recent years, in order to adapt to the new changes in market demand, part of the diesel and naphtha resources in the refinery continue to be deeply converted and used for chemical industry. In the process of conversion and utilization of heavy oil, wax oil, diesel and naphtha resources, the refinery also produces a large amount of light hydrocarbon resources. For a typical million-ton fuel oil refinery, the annual gas light hydrocarbon (C4 and below) production of the whole plant can reach one million tons, accounting for about 10% of the crude oil processing capacity. For a refining and chemical integrated enterprise or a chemical refinery, due to the further improvement of the conversion depth of crude oil resources, the light hydrocarbon production and proportion of the whole plant will be greatly increased. In order to achieve the goal of "reducing cost, improving quality and increasing efficiency" of the enterprise, how to efficiently utilize this part of light hydrocarbon resources has become the focus of attention and research of the refining and chemical industry.

[0003] Ethane is a resource that exists in oilfield associated gas, shale gas, natural gas and refinery gas. How to make full use of ethane to convert it into ethylene with high added value has become a worldwide research hotspot. There are many process routes for ethane to ethylene, and the ethane steam cracking technology has been industrialized. Ethane steam cracking is a strong endothermic reaction limited by thermodynamic equilibrium. In order to achieve sufficient single-pass conversion rate, a large amount of heat needs to be consumed. However, high temperature can accelerate the formation of surface carbon, causing rapid deactivation of the catalyst. The catalyst for direct dehydrogenation of ethane also needs to overcome the disadvantage of carbon deposition and deactivation. Ethane oxidative dehydrogenation to ethylene is an exothermic reaction that can reduce energy consumption while eliminating surface carbon and improving catalyst stability. Patent CN 105727975 B discloses a preparation method of a catalyst for ethane oxidative dehydrogenation to ethylene. The active component is Mo-V-Ni-Nb, and the carrier is any one of alumina, silica and HZSM-5. Oxygen is used as the oxidant, and a relatively high ethane conversion rate is obtained under the reaction conditions of normal pressure and 400-600℃. However, the selectivity of ethylene is low, and there is a large amount of carbon monoxide and carbon dioxide in the product. Patent CN 109433257 A discloses a catalyst for carbon dioxide oxidative dehydrogenation of ethane to ethylene. The catalyst uses carbon dioxide as the oxidant and microporous molecular sieve SSZ-13 loaded with chromium oxide as the catalyst. A nearly 40% ethane conversion rate and an ethylene selectivity close to 90% are obtained in the initial stage of the reaction. However, the catalyst deactivates quickly, and the activity decreases by half within two hours of reaction time. Moreover, the active component of chromium oxide as the catalyst makes the regeneration of the catalyst difficult, and the disposal cost of the waste catalyst is high. Patent CN 110801828 A discloses a catalyst for ethane chemical looping oxidative dehydrogenation to olefins. The catalyst uses oxygen carrier perovskite as the catalyst and the lattice oxygen in the perovskite as the oxidant. A relatively high conversion rate is obtained under the reaction conditions of normal pressure and 800℃. However, the selectivity of ethylene is low. Patent CN 109382090 B discloses a molybdenum-vanadium bimetallic oxide catalyst and its application in low-carbon alkane chemical looping dehydrogenation. The catalyst is prepared by impregnation, drying, calcination and tabletting. The use of supported molybdenum-vanadium bimetallic oxide for low-carbon alkane dehydrogenation to olefins can achieve high activity and high selectivity for the oxidative dehydrogenation of propane to propylene. The fresh oxygen carrier is changed from high valence to low valence after reacting with propane, and the low valence oxygen carrier is oxidized to high valence by air or oxygen, thereby regenerating the lattice oxygen and recycling. Moreover, the reaction performance is very stable after repeated regeneration, and the catalyst can be used in fixed bed reactors, moving bed reactors or circulating fluidized bed reactors. CN 1161307 C provides an ethane oxidative dehydrogenation catalyst. The catalyst is a transition metal impregnated modified activated carbon. The ethane conversion rate is low under the conditions of 700℃, ethane space velocity 500-5000 h-1 and pressure 0.01-1 MPa.

[0004] However, the existing catalysts for preparing ethylene by dehydrogenation of ethane still have the problem of low conversion rate and selectivity. SUMMARY

[0005] In order to overcome the above problems, the present application aims to provide a catalyst for preparing ethylene by dehydrogenation of ethane, which can significantly improve the conversion rate and selectivity of ethylene by dehydrogenation of ethane.

[0006] The inventors of the present application have unexpectedly found that the lanthanum-manganese-based and lanthanum-iron-based perovskite catalysts prepared by the citric acid combustion method have a large specific surface area, thereby significantly improving the conversion rate and selectivity of ethylene by dehydrogenation of ethane, thus obtaining the present application.

[0007] In one aspect, the present application provides a catalyst for preparing ethylene by oxidative dehydrogenation of ethane, which is a lanthanum-based perovskite catalyst and contains La x Sr 1-x MO 3-y Cl z ; wherein x is a positive number less than 1, M is Mn and / or Fe, y is a positive number less than 3, z is any value in the range of 0.01-0.5, and the specific surface area of the catalyst is 25-50 m 2 / g.

[0008] Optionally, the catalyst is further loaded with a noble metal element, and the noble metal element is Au and / or Pt; the content of the noble metal element is 0.01-2 wt% based on the total amount of the catalyst.

[0009] Optionally, the specific surface area of the catalyst is 35-45 m 2 / g; the pore volume is 0.2-0.5 cm 3 / g; the pore size is 45-60 nm; and the specific saturation magnetization is 10-100 emu / g; preferably, x is any value between 0.01 and 1, M is Mn, and y is any value between 2 and 3.

[0010] In another aspect, the present application also provides a method for preparing a catalyst for preparing ethylene by oxidative dehydrogenation of ethane, which comprises the following steps: S1, mixing an aqueous solution containing lanthanum ions, strontium ions, black metal ions, chloride ions and nitrate ions with citric acid to obtain a mixed solution, wherein the black metal ions are manganese ions and / or iron ions; S2, concentrating the mixed solution to a gel-like state to obtain a first gel-like material; S3, heating the first gel-like material in a first oxygen-containing atmosphere to make it burn to obtain a first solid material; S4, drying, grinding and calcining the first solid material to obtain a calcined material, wherein the calcining is carried out in a second oxygen-containing atmosphere and at a temperature of 600-800°C.

[0011] Optionally, in the aqueous solution, the molar ratio of the lanthanum ion, the strontium ion, the base metal ion and the chloride ion is x:1-x:1:z; x is a positive number less than 1, z is any value in the range of 0.01-0.5, the concentration of the base metal ion is 0.4-1 mol / L; the molar ratio of citric acid to the total metal elements in the mixed solution is 1:0.5-2, preferably 1:0.8-1.5.

[0012] Optionally, in step S1, the lanthanum source is lanthanum nitrate, the strontium source is strontium nitrate, the manganese source is manganese nitrate and / or manganese chloride, the iron source is iron nitrate and / or ferric chloride, and the chlorine source is manganese chloride and / or ferric chloride; the mixing temperature is 20-40℃, and the mixing time is 15-18 hours; in step S2, the concentration is performed by rotary evaporation, and the concentration temperature is 50-90℃; in step S3, the heating temperature is 200-500℃; in step S4, the drying is performed under vacuum, and the drying temperature is 100-150℃, and the drying time is 15-18 hours; the calcination time is 5-10 hours, and the heating rate is 1-3℃ / min.

[0013] Optionally, the method further comprises: S5, mixing the calcined material with an aqueous solution of a noble metal source and adding a precipitant, so that the noble metal elements in the noble metal source are deposited on the calcined material; the noble metal elements in the noble metal source are Au and / or Pt; preferably, the weight ratio of the calcined material to the noble metal elements in the noble metal source is 100:0.01-2.

[0014] In still another aspect, the present application also provides a catalyst for preparing ethylene by oxidative dehydrogenation of ethane, which is prepared by the method as described above.

[0015] In still another aspect, the present application also provides a method for preparing ethylene by oxidative dehydrogenation of ethane, which comprises: contacting the catalyst for preparing ethylene by oxidative dehydrogenation of ethane as described above with a first raw gas containing ethane and oxygen under the condition of oxidative dehydrogenation; or, the method comprises: contacting the catalyst for preparing ethylene by oxidative dehydrogenation of ethane as described above with a second raw gas containing ethane but not containing oxygen under the condition of direct dehydrogenation, to obtain a spent catalyst and a gas after contact, and the spent catalyst is subjected to oxidative regeneration.

[0016] Optionally, the condition of oxidative dehydrogenation comprises: the volume ratio of ethane to oxygen in the first raw gas is 1-3:1, the temperature is 500-700℃, the oxidative dehydrogenation is performed in a fixed bed, the weight hourly space velocity of the first raw gas passing through the fixed bed is 2.88-4.32h -1; or, the conditions of the direct dehydrogenation include: the temperature is 600-800℃, the direct dehydrogenation is carried out in a fixed bed, the weight hourly space velocity of the first raw material gas through the fixed bed is 2.88-4.32h -1 ; preferably, the first raw material gas and the second raw material gas each independently further contain 10-90% of nitrogen by volume.

[0017] By the above technical solution, the catalyst has a higher specific surface area and a larger pore volume, and can further improve the conversion rate and selectivity of the ethane dehydrogenation to ethylene. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation on the present disclosure. In the drawings:

[0019] Figure 1 X-ray diffraction patterns of lanthanum-based perovskite catalysts and X-ray diffraction patterns of lanthanum-based perovskite catalysts doped with different metal elements.

[0020] Figure 2 X-ray diffraction patterns of lanthanum-based perovskite catalysts and X-ray diffraction patterns of lanthanum-based perovskite catalysts doped with different metal elements.

[0021] Figure 3 Mn2P 3 / 2 X-ray photoelectron spectrograms.

[0022] Figure 4 O1S X-ray photoelectron spectrograms of lanthanum-based perovskite catalysts and lanthanum-based perovskite catalysts doped with different metal elements.

[0023] Figure 5 Oxidative dehydrogenation reactivity of lanthanum-based perovskite catalysts.

[0024] Figure 6 Room temperature hysteresis loops of lanthanum-based perovskite catalysts. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0026] In one aspect, the present application provides a catalyst for the oxidative dehydrogenation of ethane to ethylene, which is a lanthanum-based perovskite catalyst and contains La x Sr 1-x MO 3-y Cl z; wherein x is a positive number less than 1, M is Mn and / or Fe, y is a positive number less than 3, and z is any value in the range of 0.01-0.5; the specific surface area of the catalyst is 25-50 m 2 / g.

[0027] The catalyst for preparing ethylene by oxidative dehydrogenation of ethane has a large specific surface area, thereby improving the conversion rate and selectivity of ethylene by oxidative dehydrogenation of ethane.

[0028] According to a particularly preferred embodiment of the present application, the catalyst is further loaded with a noble metal element, and the noble metal element is Au and / or Pt; the content of the noble metal element is 0.01-2 wt% based on the total amount of the catalyst; in this preferred embodiment, the conversion rate and selectivity of ethylene by oxidative dehydrogenation of ethane are further improved.

[0029] Optionally, the specific surface area of the catalyst is 35-45 m 2 / g; the pore volume is 0.2-0.5 cm 3 / g; the pore size is 45-60 nm; the specific saturation magnetization is 10-100 emu / g; preferably, x is any value between 0.01-1, M is Mn, and y is any value between 0.01-3.

[0030] In another aspect, the present application further provides a method for preparing a catalyst for preparing ethylene by oxidative dehydrogenation of ethane, which comprises the following steps: S1, mixing an aqueous solution containing lanthanum ions, strontium ions, black metal ions, chloride ions and nitrate ions with citric acid to obtain a mixed solution, wherein the black metal source is a manganese source and / or an iron source; S2, concentrating the mixed solution to obtain a first gelatinous substance; S3, heating the first gelatinous substance in a first oxygen-containing atmosphere to make it burn to obtain a first solid material; S4, drying, grinding and calcining the first solid material to obtain a calcined material, wherein the calcination is carried out in a second oxygen-containing atmosphere and at a temperature of 600-800°C.

[0031] The first oxygen-containing atmosphere and the second oxygen-containing atmosphere are each independently air and / or oxygen.

[0032] The citric acid is complexed with the lanthanum ions, strontium ions and black metal ions, and forms a gelatinous substance in the concentration process, and the gelatinous substance has a delicate network structure; and in the presence of oxygen, the nitrate ions in the gelatinous substance have oxidizing properties, which initiate the combustion of the organic components (citric acid) therein under heating conditions to form a fluffy first solid material (burnt residue), and the calcined material obtained after drying, grinding and calcining the first solid material has a large specific surface area.

[0033] Optionally, in the aqueous solution, the molar ratio of the lanthanum ion, the strontium ion, the ferrous ion and the chloride ion is x:1-x:1:z; x is a positive number less than 1, and z is any value in the range of 0.01-0.5; the molar ratio of citric acid to the total metal elements in the mixed solution can be 1:0.5-2, preferably 1:0.8-1.5.

[0034] The source of the lanthanum ion can be lanthanum nitrate, the source of the strontium ion can be strontium nitrate, the source of the manganese ion can be manganese nitrate and / or manganese chloride, the source of the iron ion can be ferric nitrate and / or ferric chloride, and the source of the chloride ion can be manganese chloride and / or ferric chloride.

[0035] Optionally, in step S1, the temperature of the mixing is 20-40℃, and the time is 15-18 hours; in step S2, the concentration is performed by rotary evaporation, and the temperature of the concentration is 50-90℃; in step S3, the temperature of the heating is 200-500℃; in step S4, the drying is performed under vacuum, and the temperature is 100-150℃, and the time is 15-18h; the calcination time is 5-10h, and the heating rate is 1-3℃ / min.

[0036] Optionally, the method further comprises: S5, mixing the calcined material with an aqueous solution of a noble metal source and adding a precipitant, so that the noble metal elements in the noble metal source are deposited on the calcined material; the noble metal elements in the noble metal source are Au and / or Pt; preferably, the weight ratio of the calcined material to the noble metal elements in the noble metal source is 100:0.01-2.

[0037] According to a particularly preferred embodiment of the present application, the method for preparing the catalyst for preparing ethylene by oxidative dehydrogenation of ethane according to the present application comprises the following steps: S1, mixing an aqueous solution containing lanthanum ions, strontium ions, ferrous ions, chloride ions and nitrate ions with citric acid to obtain a mixed solution, wherein the molar ratio of the lanthanum ions, the strontium ions, the ferrous ions and the chloride ions in the aqueous solution is x:1-x:1:z; x is a positive number less than 1, z is any value in the range of 0.01-0.5, the concentration of the ferrous ions is 0.4-1 mol / L, the temperature of the mixing is 20-40℃, the time is 15-18 hours, and the molar ratio of citric acid to the total metal elements in the mixed solution is 1:0.8-1.5; S2, concentrating the mixed solution to obtain a first gelatinous substance, wherein the concentration is performed by rotary evaporation, and the temperature of the concentration is 50-90℃; S3, heating the first gelatinous substance in a first oxygen-containing atmosphere to make it burn to obtain a first solid material, wherein the heating temperature is 200-500℃; S4, drying, grinding and calcining the first solid material to obtain a calcined material, wherein the temperature of the drying is 100-150℃, the time is 15-18 hours, the calcination is performed in a second oxygen-containing atmosphere, and the temperature is 600-800℃; the time of the calcination is 5-10 hours, and the heating rate is 1-3℃ / min. More preferably, the method further comprises: S5, mixing the calcined material with an aqueous solution of a noble metal source and adding a precipitant to make noble metal elements in the noble metal source deposited on the calcined material; the noble metal elements in the noble metal source are Au and / or Pt; and the weight ratio of the calcined material to the noble metal elements in the noble metal source is 100:0.01-2.

[0038] In another aspect, the present application also provides the catalyst for preparing ethylene by oxidative dehydrogenation of ethane prepared by the method as described above.

[0039] In another aspect, the present application also provides a method for preparing ethylene by oxidative dehydrogenation of ethane, which comprises: contacting the catalyst for preparing ethylene by oxidative dehydrogenation of ethane as described above with a first raw gas containing ethane and oxygen under the condition of oxidative dehydrogenation in the presence of oxygen; or the method comprises: contacting the catalyst for preparing ethylene by oxidative dehydrogenation of ethane as described above with a second raw gas containing ethane but not containing oxygen under the condition of direct dehydrogenation to obtain a spent catalyst and a gas after the contacting, and performing oxidative regeneration on the spent catalyst.

[0040] Optionally, the condition of oxidative dehydrogenation in the presence of oxygen comprises: the volume ratio of ethane to oxygen in the first raw gas is 1-3:1, the temperature is 500-700℃, the oxidative dehydrogenation is performed in a fixed bed, the weight hourly space velocity of the first raw gas through the fixed bed is 2.88-4.32h -1; or, the conditions of the direct dehydrogenation include: the temperature is 600-800℃, the direct dehydrogenation is carried out in a fixed bed, the weight hourly space velocity of the first raw material gas through the fixed bed is 2.88-4.32h -1 ; preferably, the first raw material gas and the second raw material gas each independently further contain 10-90% of nitrogen by volume.

[0041] In the process of the dehydrogenation in the presence of oxygen, the ethane in the first raw material gas is subjected to free radical oxidative dehydrogenation under the oxidation of oxygen and the catalysis of the catalyst. In the process of the direct dehydrogenation, the ethane in the second raw material gas is subjected to oxidation under the oxidation of the catalyst in the oxidation state to generate the contacted gas containing ethylene, and the spent catalyst in the reduction state is obtained. After the spent catalyst is contacted with the gas containing oxygen (for example, air) to be subjected to oxidation regeneration, the catalyst in the oxidation state is obtained for continuous use, that is, in the process of the direct dehydrogenation, the ethane is intermittently contacted with the catalyst, so that the direct contact with oxygen is avoided, and the conversion rate and the selectivity of the production of ethylene can be further improved.

[0042] The present application is further illustrated in detail by the following examples. The raw materials used in the examples can be obtained through commercial channels.

[0043] Example 1

[0044] In this example, La 0.8 Sr 0.2 MnO 3-y Cl z .

[0045] An aqueous solution containing lanthanum ions, strontium ions, manganese ions, chloride ions and nitrate ions (lanthanum nitrate, strontium nitrate, manganese nitrate, manganese chloride are dissolved in water to obtain, wherein the concentration of manganese ions is 0.5 mol / L) is mixed with citric acid to obtain a mixed solution, the molar ratio of the lanthanum ions, the strontium ions, the manganese ions and the chloride ions in the aqueous solution is x:1-x:1:z; x is 0.8, z is 0.4, the mixing temperature is 30°C, the time is 16 hours, the molar ratio of citric acid to total metal elements in the mixed solution is 1:1.2; S2, the mixed solution is concentrated to a gel to obtain a first gel, the concentration is carried out by rotary evaporation, the concentration temperature is 70°C; S3, the first gel is placed in a crucible and heated with an electric furnace, the first gel is heated to burn in a first oxygen-containing atmosphere (air) to obtain a first solid material, the heating temperature is 350°C; S4, the first solid material is dried, ground and calcined to obtain a calcined material, the drying temperature is 120°C, the time is 16h, the calcination is carried out in a second oxygen-containing atmosphere (air) and the temperature is 700°C; the calcination time is 8h, the heating rate is 2°C / min. After calcination, natural cooling is carried out to obtain a calcined material, the elemental composition is determined, and the calcined material is La 0.8 Sr 0.2 MnO 3-y Cl z , y is 0.3, z is 0.4, that is, the catalyst prepared in this embodiment.

[0046] Example 2

[0047] In this embodiment, 0.7wt% Au / La 0.8 Sr 0.2 MnO 3-y Cl z .

[0048] The preparation of the catalyst is carried out according to the method of Example 1, except that step S5 is also carried out: S5, the calcined material is mixed with an aqueous solution of a noble metal source (HAuCl4 solution) and a precipitating agent (NaOH, the pH value is adjusted to neutral) is added, so that the noble metal elements in the noble metal source are deposited on the calcined material; the noble metal elements in the noble metal source are Au; the weight ratio of the calcined material to the noble metal elements in the noble metal source is 100:0.07.

[0049] Example 3

[0050] In this embodiment, La 0.8 Sr 0.2 FeO 3-y Cl z .

[0051] The preparation of catalyst was carried out according to the method of Example 1, except that manganese nitrate and manganese chloride were replaced by iron nitrate and iron chloride respectively.

[0052] Comparative Example 1

[0053] This comparative example prepared LaMnO3.

[0054] The preparation was carried out according to the method of Example 1, except that strontium nitrate and manganese chloride were replaced by lanthanum nitrate and manganese nitrate respectively.

[0055] Comparative Example 2

[0056] This comparative example prepared LaMnO3. 3-y Cl z .

[0057] The preparation was carried out according to the method of Example 1, except that strontium nitrate was replaced by lanthanum nitrate.

[0058] Comparative Example 3

[0059] This comparative example prepared LaMnO3. 0.8 Sr 0.2 .

[0060] The preparation was carried out according to the method of Example 1, except that manganese chloride was replaced by manganese nitrate.

[0061] Comparative Example 4

[0062] This comparative example prepared LaFeO3.

[0063] The preparation was carried out according to the method of Example 3, except that strontium nitrate and iron chloride were replaced by lanthanum nitrate and iron nitrate respectively.

[0064] Comparative Example 5

[0065] This comparative example prepared LaFeO3. 0.8 Sr 0.2 .

[0066] The preparation was carried out according to the method of Example 3, except that iron chloride was replaced by iron nitrate.

[0067] Test Example 1

[0068] The catalysts of Example 1, 3 and Comparative Examples 1-5 were subjected to X-ray diffraction and X-ray photoelectron spectroscopy, and the results are shown in Table 1. Figures 1-4 Figures 1-4 The results show that the doping of Sr and Cl has no effect on the perovskite structure, and the amount of oxygen vacancies in the catalyst increases after doping of Sr and Cl.

[0069] ​Test Example 2

[0070] The catalysts of Example 1 and Comparative Examples 1-3 were measured for specific surface area, pore volume, pore size, and specific saturation magnetization according to the method described in the literature "Catalyst Characterization" (2008, East China University of Science and Technology Press, Wang Xingyi). The results are shown in Table 1 and Figure 6 The results of Table 1 show that the Sr and Cl co-doped perovskite structure catalysts prepared using the citric acid combustion method have larger pore volume and pore size, and have relatively high specific surface area and specific saturation magnetization.

[0071] Table 1

[0072]

[0073] Test Example 3

[0074] This test example was conducted for a test of dehydrogenation under oxygen.

[0075] The catalysts of Examples 1-3 and Comparative Examples 1-5 were tested under the following fixed bed reaction conditions: a pressure of atmospheric pressure, a temperature of 675°C, a feed gas containing ethane, oxygen, and nitrogen at a volume ratio of 2:1:4, and a weight hourly space velocity of 3.6 h -1 The catalyst was loaded in an amount of 0.5 g. The ethane conversion, ethylene selectivity, methane selectivity, CO selectivity, CO2 selectivity, C3 selectivity, C4 selectivity, and the number of C's at the outlet / number of C's at the inlet were measured. The results are shown in Table 2 and Table 3 and Figure 5 The results of Table 2 and Table 3 show that the doping of Sr and Cl effectively increases the ethylene selectivity and decreases the CO2 selectivity, and that the ethylene selectivity is increased and the CO2 selectivity is further decreased after loading of Au. The lanthanum-manganese-based perovskite catalyst shows higher ethylene selectivity and lower CO2 selectivity than the lanthanum-iron-based perovskite catalyst.

[0076] Table 2

[0077]

[0078] Table 3

[0079]

[0080] Test Example 4

[0081] This test example was conducted for a test of direct dehydrogenation.

[0082] The catalysts of Examples 1-2 were tested under the following fixed bed reaction conditions: a pressure of atmospheric pressure, a temperature of 650-750°C, a feed gas containing ethane and nitrogen at a volume ratio of 1:4, and a weight hourly space velocity of 3.6 h -1The amount of catalyst loaded was 0.5 g. The ethane conversion and ethylene selectivity were measured, and the results are shown in Table 4. After 10 minutes of feeding the raw material gas, the feeding of the raw material gas was stopped, and instead, air was fed to perform calcination at 600°C for 10 minutes to perform regeneration.

[0083] Table 4

[0084]

[0085] The results of Table 4 show that direct dehydrogenation can further improve the ethane conversion and ethylene selectivity, and after loading Au, the selectivity of ethylene is slightly reduced, but the conversion of ethane is higher, and the yield of ethylene is higher after comprehensive calculation.

[0086] The above describes the preferred embodiments of the present disclosure in detail, but the present disclosure is not limited to the specific details in the above-described embodiments, and within the technical concept range of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection range of the present disclosure.

[0087] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combination manners are not described again in the present disclosure.

[0088] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as it does not deviate from the idea of the present disclosure, and it should also be considered as disclosed by the present disclosure.

Claims

1. A catalyst for the oxidative dehydrogenation of ethane to ethylene, characterized in that, The catalyst is a lanthanum-based perovskite catalyst and contains La x Sr 1-x MO 3-y Cl z ; wherein x is a positive number less than 1, M is Mn and / or Fe, y is a positive number less than 3, and z is any value in the range of 0.01-0.5; the specific surface area of the catalyst is 25-50 m 2 / g, the pore volume is 0.2-0.5 cm 3 / g, and the pore size is 45-60 nm. The catalyst is prepared by a method comprising the following steps: S1. An aqueous solution containing lanthanum ions, strontium ions, ferrous metal ions, chloride ions and nitrate ions is mixed with citric acid to obtain a mixed solution, wherein the ferrous metal ions are manganese ions and / or iron ions. S2. Concentrate the mixture to a gel state to obtain a first gel-like substance; S3. Heat the first gelatinous substance in a first oxygen-containing atmosphere to cause it to burn, thereby obtaining a first solid material; the heating temperature is 200-500℃. S4. The first solid material is dried, ground and calcined to obtain the calcined material. The calcination is carried out in a second oxygen-containing atmosphere at a temperature of 600-800℃.

2. The catalyst according to claim 1, characterized in that, The catalyst is also loaded with a noble metal element, namely Au and / or Pt; the content of the noble metal element is 0.01-2 wt% based on the total amount of the catalyst.

3. The catalyst according to claim 1, characterized in that, The average particle size of the catalyst is 60-90 μm; the specific surface area is 35-45 m 2 / g; and the specific saturation magnetization is 10-100 emu / g.

4. The catalyst according to claim 1 or 3, characterized in that, x is any value between 0.01 and 1, M is Mn, and y is any value between 2 and 3.

5. A method for preparing the catalyst for the oxidative dehydrogenation of ethane to ethylene according to any one of claims 1-4, characterized in that, The method includes the following steps: S1. An aqueous solution containing lanthanum ions, strontium ions, ferrous metal ions, chloride ions and nitrate ions is mixed with citric acid to obtain a mixed solution, wherein the ferrous metal ions are manganese ions and / or iron ions. S2. Concentrate the mixture to a gel state to obtain a first gel-like substance; S3. Heat the first gelatinous substance in a first oxygen-containing atmosphere to cause it to burn, thereby obtaining a first solid material; the heating temperature is 200-500℃. S4. The first solid material is dried, ground and calcined to obtain the calcined material. The calcination is carried out in a second oxygen-containing atmosphere at a temperature of 600-800℃.

6. The method according to claim 5, characterized in that, In the aqueous solution, the concentration of the black metal ions is 0.4-1 mol / L; The molar ratio of citric acid to the total metal elements in the mixture is 1:0.5-2.

7. The method according to claim 6, characterized in that, The molar ratio of citric acid to the total metal elements in the mixture is 1:0.8-1.

5.

8. The method according to claim 5, characterized in that, In step S1, the mixing temperature is 20-40℃ and the time is 15-18 hours; In step S2, the concentration is carried out by rotary evaporation, and the concentration temperature is 50-90℃. In step S4, the drying temperature is 100-150℃ and the time is 15-18h; the calcination time is 5-10h and the heating rate is 1-3℃ / min.

9. The method according to claim 5, characterized in that, The method also includes: S5. The calcined material is mixed with an aqueous solution of a precious metal source and a precipitant is added, so that the precious metal element in the precious metal source is deposited on the calcined material; the precious metal element in the precious metal source is Au and / or Pt.

10. The method according to claim 9, characterized in that, The weight ratio of the calcined material to the precious metal element in the precious metal source is 100:0.01-2.

11. A method for the oxidative dehydrogenation of ethane to produce ethylene, characterized in that, The method includes: contacting the catalyst for ethane oxidative dehydrogenation to ethylene as described in any one of claims 1-4 with a first feed gas containing ethane and oxygen under oxygen-containing dehydrogenation conditions; Alternatively, the method may include: under direct dehydrogenation conditions, contacting the catalyst for ethane oxidative dehydrogenation to ethylene as described in any one of claims 1-4 with a second feed gas containing ethane but not oxygen to obtain a spent catalyst and the contacted gas, and then oxidizing and regenerating the spent catalyst.

12. The method according to claim 11, characterized in that, The conditions for oxygen-induced dehydrogenation include: a volume ratio of ethane to oxygen in the first feed gas of 1-3:1, a temperature of 500-700℃, and the oxygen-induced dehydrogenation being carried out in a fixed bed with a weight hourly space velocity (WHSV) of 2.88-4.32 h⁻¹ for the first feed gas passing through the fixed bed. -1 ; Alternatively, the conditions for direct dehydrogenation include: a temperature of 600-800°C, the direct dehydrogenation being carried out in a fixed bed, and a weight hourly space velocity (WHSV) of 2.88-4.32 h⁻¹ for the second feed gas passing through the fixed bed. -1 .

13. The method according to claim 12, characterized in that, The first raw material gas and the second raw material gas each independently contain 10-90% by volume of nitrogen.

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