Method for preparing ethylene by oxidizing ethane with carbon dioxide

Abstract

The invention provides a method for preparing ethylene by oxidizing ethane with carbon dioxide, and relates to the field of chemical industry. According to the method, ethane and carbon dioxide are fully preheated and mixed and then are introduced into microwave-heated multi-stage series quartz tube reactors for reaction, a vanadium-aluminum-titanium structured catalyst is loaded in each stage of quartz tube reactor, and a preheating unit and a water vapor supplementing unit are connected between every two stages of quartz tube reactors; by adopting the method disclosed by the invention, the ethylene can be prepared by dehydrogenating the ethane oxidized by the carbon dioxide at the low temperature of below 500 DEG C, the conversion rate of the ethane can be up to 51%, and the reaction energy consumption is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a method for preparing ethylene by oxidizing ethane with carbon dioxide. Background Art

[0002] Ethylene is the leading product of the petrochemical industry and one of the important indicators of a country's petrochemical development level. As an important basic chemical raw material, countries around the world generally regard the ethylene industry as an important part of their industrial layout, and ethylene production is also seen as a reflection of a country's comprehensive economic strength. At present, the main methods for producing ethylene include steam cracking, ethane oxidative dehydrogenation, natural gas ethylene production, and coal ethylene production. As oil resources become increasingly scarce, the raw material for producing ethylene using ethane oxidative dehydrogenation is the most economical, and the current methods for producing ethylene from ethane include thermal cracking and oxidative dehydrogenation.

[0003] Thermal cracking is a traditional method for producing ethylene from ethane. It is limited by the reaction itself. Although the equipment and process are becoming more and more perfect, the ethylene production process has the disadvantages of complex reaction operation, high energy consumption, low single-pass conversion rate of reactant ethane, easy coking of the reaction device, etc., and the overall reaction investment cost is high. Oxidative dehydrogenation includes ethane oxidative cracking and ethane catalytic oxidative dehydrogenation. Among them, ethane oxidative cracking is an ethane oxidative dehydrogenation reaction in which gas-phase oxygen is introduced into the reaction system. Since oxygen is introduced into the reaction, the selectivity of ethylene is not high, and the main by-products carbon monoxide and ethylene are not easy to separate, and purification and separation are difficult. The catalytic oxidative dehydrogenation of ethane mainly uses steam cracking technology to produce ethylene. Although the modified method has basically achieved industrialization, due to the limitation of thermodynamic equilibrium conversion rate, the reaction temperature is basically above 850°C, and the energy consumption is extremely high.

[0004] The prior art proposes to introduce a mild oxidant, carbon dioxide, into the reaction system of ethylene produced by catalytic oxidative dehydrogenation of ethane. Considering that carbon dioxide will not promote deep oxidation of ethane, the selectivity of the product ethylene can also be guaranteed; at the same time, the reaction can provide part of the energy for the dehydrogenation endothermic reaction, reduce the reaction temperature, and meet the current environmental protection needs. In the actual production process, although the introduction of carbon dioxide as an oxidant into the reaction system of ethylene produced by catalytic oxidative dehydrogenation of ethane can reduce the reaction energy consumption, the ethane selectivity and conversion rate are relatively low, and a catalyst needs to be added to catalyze the reaction; and with the addition of the catalyst, the side reactions also increase.

[0005] In summary, from the perspective of energy consumption and reaction efficiency, the process of low-temperature carbon dioxide oxidation of ethane dehydrogenation to produce ethylene has a very ideal prospect for industrial low-cost and high-yield production of ethylene through further in-depth exploration of how to reduce the occurrence of side reactions. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing ethylene by oxidizing ethane with carbon dioxide, so as to achieve the technical effect of preparing ethylene by dehydrogenating ethane with low-temperature carbon dioxide oxidation, which not only reduces the overall reaction cost, but also effectively reduces the occurrence of side reactions and improves the ethane conversion rate.

[0007] To achieve the above object, the present invention proposes the following technical scheme: a method for preparing ethylene by oxidizing ethane with carbon dioxide, wherein the preheated carbon dioxide and ethane mixed gas is introduced into a multi-stage series quartz tube reactor heated by microwaves for reaction, each stage of the quartz tube reactor is loaded with a vanadium aluminum titanium structured catalyst, and a preheating unit and a water vapor supplement unit are connected between each stage of the quartz tube reactor;

[0008] The vanadium-aluminum-titanium structured catalyst is a vanadium-aluminum-titanium composite catalyst with vanadium as an active component and a pore width of 0.5-2 mm.

[0009] Furthermore, the method comprises the following steps:

[0010] 1) Building a reaction platform for preparing ethylene by oxidizing ethane with carbon dioxide, comprising: a preheater and a multi-stage series-connected microwave-heated quartz tube reactor, wherein each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium structured catalyst, and a preheating unit and a water vapor supplementing unit are connected between each stage of the quartz tube reactor;

[0011] 2) Pretreatment: preheating the mixed gas of carbon dioxide and ethane to the first reaction condition according to the reaction conditions of ethylene production by oxidation of ethane with carbon dioxide, and microwave heating the multi-stage series quartz tube reactor to the second reaction condition;

[0012] 3) Catalytic reaction: a mixed gas of carbon dioxide and ethane preheated to a first reaction condition is introduced into a multi-stage series quartz tube reactor heated by microwaves to a second reaction condition for reaction. During the reaction, water vapor is added to the multi-stage series quartz tube reactor to a third reaction condition. After the reaction is completed, the ethane conversion rate and the ethylene selectivity are respectively measured.

[0013] Furthermore, the preheated carbon dioxide and ethane mixed gas has a pressure of 0.05-0.2 MPa and a temperature of 150-250°C.

[0014] Furthermore, the number of stages of the multi-stage series quartz tube reactors is 2-5, preferably 4.

[0015] Furthermore, the microwave heating temperature of the multi-stage series quartz tube reactor is 450-500°C.

[0016] Furthermore, the mass fraction of vanadium, an active component of the vanadium-aluminum-titanium structured catalyst, is 2%-10%, preferably 8%.

[0017] Furthermore, the total amount of water vapor added during the reaction of the multi-stage series quartz tube reactor is 1%-5%, preferably 2%.

[0018] It can be seen from the above technical solutions that the technical solutions of the present invention have the following beneficial effects:

[0019] The method for preparing ethylene by oxidizing ethane with carbon dioxide disclosed in the present invention adopts a method in which ethane and carbon dioxide are fully preheated and mixed and then introduced into a multi-stage series quartz tube reactor for microwave heating for reaction, wherein each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium regular catalyst and a preheating unit and a water vapor replenishing unit are connected between each stage of the quartz tube reactor; when implemented, when the content of vanadium as an active component in the four-stage series quartz tube reactor and the vanadium-aluminum-titanium regular catalyst is 8% and the amount of water vapor replenished is 2%, the method of the present invention can achieve the preparation of ethylene by oxidizing ethane with carbon dioxide at a low temperature below 500°C with an ethane conversion rate of 51%, thereby greatly reducing the reaction energy consumption and the occurrence of side reactions.

[0020] The method of the present invention greatly reduces the reaction temperature of preparing ethylene by oxidizing ethane with carbon dioxide, and reduces the reaction energy consumption; by utilizing the characteristics of microwave heating and high-temperature steam to resist carbon deposition, the reaction of preparing ethylene by ethane at low temperature has a higher ethane conversion rate and ethylene selectivity.

[0021] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0022] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0024] Figure 1 The present invention is a flow chart of the method for preparing ethylene by oxidation of ethane with carbon dioxide. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0026] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] Although the production of ethylene by steam cracking technology based on ethane catalytic oxidation dehydrogenation has been basically industrialized, it is a high-temperature reaction with extremely high energy consumption. The prior art proposes the production of ethylene by low-temperature carbon dioxide oxidation dehydrogenation of ethane, but the need to use a catalyst to catalyze the reaction leads to an increase in side reactions. The present invention aims to solve the problems existing in the production of ethylene by low-temperature carbon dioxide oxidation dehydrogenation of ethane, and by designing a method flow for the production of ethylene by low-temperature carbon dioxide oxidation dehydrogenation of ethane, the ethane conversion rate can be improved while reducing the reaction energy consumption.

[0028] Specifically, the method for preparing ethylene by oxidizing ethane with carbon dioxide disclosed in the present invention is based on the principle of introducing preheated carbon dioxide and ethane mixed gas into a multi-stage series quartz tube reactor heated by microwave for reaction, each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium regular catalyst, and each stage of the quartz tube reactor is connected with a preheating unit and a water vapor replenishing unit; in the implementation, the selected vanadium-aluminum-titanium regular catalyst is a vanadium-aluminum-titanium composite catalyst with vanadium of 2%-10% by mass as an active component and a pore width of 0.5-2mm, and the mass fraction of aluminum in the vanadium-aluminum-titanium composite catalyst is about 15%; the vanadium-aluminum-titanium composite catalyst is made into a regular and uniform shape, wherein vanadium, aluminum and titanium all exist in the form of oxides, and the oxides of aluminum and titanium mainly support the regular structure of the catalyst and form internal pores.

[0029] The preparation method may include the following steps when implemented Figure 1 Steps shown:

[0030] Step S1, building a reaction platform for preparing ethylene by oxidizing ethane with carbon dioxide, including: a preheater and a multi-stage series quartz tube reactor for microwave heating connected in sequence, wherein each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium structured catalyst, and a preheating unit and a water vapor replenishing unit are connected between each stage of the quartz tube reactor; the preheating unit and the water vapor replenishing unit can be directly composed of the preheater and the water vapor replenishing unit.

[0031] Step S1, pretreatment: preheating the mixed gas of carbon dioxide and ethane to a first reaction condition according to the reaction conditions of ethylene production by oxidation of ethane with carbon dioxide, and microwave heating the multi-stage series quartz tube reactor to a second reaction condition;

[0032] Step S3, catalytic reaction: a mixed gas of carbon dioxide and ethane preheated to a first reaction condition is introduced into a multi-stage series quartz tube reactor heated by microwaves to a second reaction condition for reaction, water vapor is added to the multi-stage series quartz tube reactor during the reaction to a third reaction condition, and after the reaction is completed, the ethane conversion rate and ethylene selectivity are respectively measured.

[0033] Optionally, the pressure of the preheated carbon dioxide and ethane mixed gas is 0.05-0.2MPa, and the temperature is 150-250°C; the number of stages of the multi-stage series quartz tube reactor is 2-5, the temperature of microwave heating is 450-500°C, the total amount of water vapor supplemented during the reaction is 1%-5%, and the supplement of water vapor is intended to increase the efficiency of microwave heating; the mass fraction of vanadium, the active component of the vanadium-aluminum-titanium regular catalyst, is 2%-10%.

[0034] The core of the preparation method of the present invention is to reduce the energy consumption of ethane oxidative cracking and improve the reaction efficiency; through microwave heating and supplementing with appropriate water vapor, the heating is uniform, and the reaction conversion rate and selectivity are improved; the reaction space velocity is increased by regularizing the catalyst, the reaction efficiency is improved, and the occurrence of side reactions is reduced.

[0035] The process for producing ethylene by dehydrogenation of ethane by oxidation of ethane with carbon dioxide at low temperature disclosed in the present invention will be further described in detail below in conjunction with specific embodiments.

[0036] Example 1

[0037] A mixture of carbon dioxide and ethane was preheated to 0.2MPa, 200°C at 100ml / min, and reacted in a two-stage series empty quartz tube reactor, where the reaction tube was heated to 500°C by an electric heating wire; after the reaction, the ethane conversion rate was measured to be 14% and the ethylene selectivity was 82%.

[0038] Example 2

[0039] The mixture of carbon dioxide and ethane was preheated to 0.2MPa and 200°C at 100ml / min, and the reaction was carried out in a two-stage series empty quartz tube reactor. The reaction tube was heated to 500°C by microwave. After the reaction, the ethane conversion rate was measured to be 23% and the ethylene selectivity was 78%.

[0040] Example 3

[0041] The mixed gas of carbon dioxide and ethane was preheated to 0.2MPa and 200°C at 100ml / min, and the reaction was carried out in a two-stage series-connected quartz tube reactor loaded with a vanadium-aluminum-titanium structured catalyst. The reaction tube was heated to 500°C by microwave, the pore width of the vanadium-aluminum-titanium structured catalyst was 0.5mm, and the vanadium content was 10%. After the reaction, the ethane conversion rate was measured to be 42% and the ethylene selectivity was 87%.

[0042] Example 4

[0043] The mixed gas of carbon dioxide and ethane was preheated to 0.05MPa and 150°C at 100ml / min, and the reaction was carried out in a two-stage series-connected quartz tube reactor loaded with a vanadium-aluminum-titanium structured catalyst. The reaction tube was heated to 450°C by microwave, the pore width of the vanadium-aluminum-titanium structured catalyst was 2mm, and the vanadium content was 1%. After the reaction, the ethane conversion rate was measured to be 33%, and the ethylene selectivity was 93%.

[0044] Example 5

[0045] The mixed gas of carbon dioxide and ethane was preheated to 0.05MPa and 150°C at 100ml / min, and the reaction was carried out in a two-stage series-connected quartz tube reactor loaded with a vanadium-aluminum-titanium structured catalyst, and 1% water vapor was added after the first-stage reaction. The reaction tube was heated to 500°C by microwave, the pore width of the vanadium-aluminum-titanium structured catalyst was 2mm, and the vanadium content was 5%. After the reaction, the ethane conversion rate was measured to be 47%, and the ethylene selectivity was 92%.

[0046] Example 6

[0047] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa and 200℃ at 100ml / min, and the reaction was carried out in a quartz tube reactor loaded with a vanadium aluminum titanium structured catalyst in four stages in series, and 2% water vapor was added in the first and second reactors. The reaction tube was heated to 500℃ by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 8%. After the reaction, the ethane conversion rate was measured to be 51%, and the ethylene selectivity was 88%.

[0048] Example 7

[0049] The mixture of carbon dioxide and ethane was preheated to 0.10MPa and 200°C at 100ml / min, and the reaction was carried out in a four-stage series of quartz tube reactors loaded with vanadium aluminum titanium structured catalysts, and 2% water vapor was added in the first and second reactors. The reaction tube was heated to 600°C by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 8%. After the reaction, the ethane conversion rate was measured to be 68%, and the ethylene selectivity was 55%.

[0050] Example 8

[0051] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa and 200℃ at 100ml / min, and the reaction was carried out in a quartz tube reactor loaded with a vanadium aluminum titanium structured catalyst in four stages in series, and 5% water vapor was added in the first and second reactors. The reaction tube was heated to 600℃ by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 8%. After the reaction, the ethane conversion rate was measured to be 59%, and the ethylene selectivity was 70%.

[0052] Example 9

[0053] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa, 200℃, and four-stage quartz tube reactors loaded with vanadium aluminum titanium structured catalyst were connected in series to react, and 5% water vapor was added in the multi-stage reactor. The reaction tube was heated to 500℃ by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 8%. After the reaction, the ethane conversion rate was measured to be 45%, and the ethylene selectivity was 88%.

[0054] Example 10

[0055] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa and 200°C at 100ml / min, and the reaction was carried out in a quartz tube reactor loaded with a vanadium-aluminum-titanium structured catalyst in four stages in series, and 2% water vapor was added in the first and second reactors. The reaction tube was heated to 500°C by microwave, the pore width of the vanadium-aluminum-titanium structured catalyst was 1mm, and the vanadium content was 2%. After the reaction, the ethane conversion rate was measured to be 40%, and the ethylene selectivity was 83%.

[0056] Embodiment 11

[0057] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa and 200°C at 100ml / min, and the reaction was carried out in a quartz tube reactor loaded with a vanadium-aluminum-titanium structured catalyst in four stages in series, and 2% water vapor was added in the first and second reactors. The reaction tube was heated to 500°C by microwave, the pore width of the vanadium-aluminum-titanium structured catalyst was 2mm, and the vanadium content was 8%. After the reaction, the ethane conversion rate was measured to be 44%, and the ethylene selectivity was 91%.

[0058] Example 12

[0059] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa, 200℃, and five-stage series-connected quartz tube reactors loaded with vanadium aluminum titanium structured catalysts were reacted, and 5% water vapor was added in the multi-stage reactors. The reaction tube was heated to 500℃ by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 3%. After the reaction, the ethane conversion rate was measured to be 41%, and the ethylene selectivity was 93%.

[0060] Embodiment 13

[0061] The mixed gas of carbon dioxide and ethane was preheated to 0.10MPa, 200℃, and five-stage quartz tube reactors loaded with vanadium aluminum titanium structured catalyst were connected in series to react, and 5% water vapor was added in the multi-stage reactor. The reaction tube was heated to 500℃ by microwave, the pore width of the vanadium aluminum titanium structured catalyst was 1mm, and the vanadium content was 10%. After the reaction, the ethane conversion rate was measured to be 43%, and the ethylene selectivity was 90%.

[0062] Based on the above examples, it is found that compared with heating with electric heating wire, the microwave heating method of the reactor helps to improve the conversion rate of ethane, because the heating efficiency of the electric heating wire is low and the heating is uneven; under the same microwave heating method, the addition of a catalyst does help to improve the reaction efficiency of low-temperature carbon dioxide oxidation ethane dehydrogenation to ethylene, and the more active components in the catalyst and the smaller the pores, the higher the catalytic efficiency; further examples show that by adding water vapor to the reactor, the microwave heating efficiency can be increased, the reaction efficiency can be further improved, and the ethane conversion rate can be increased. Combined with the reaction results of Examples 6-11 and 12-13, when the mass fraction of the active component vanadium of the vanadium aluminum titanium structured catalyst is 8%, the pore width is 1mm, the number of stages of the multi-stage series quartz tube reactor is 4, and the total amount of water vapor added during the reaction is 2%, the highest ethane conversion rate can be obtained, reaching 51%, which is significantly better than the ethane conversion rate in the prior art, and the selectivity of ethylene can reach up to 93%. It is fully proved that the method for preparing ethylene by oxidizing ethane with carbon dioxide proposed in the present invention can effectively achieve the purpose of preparing ethylene by dehydrogenating ethane with carbon dioxide at low temperature, and obtain the technical effect of significantly reducing reaction energy consumption and improving reaction efficiency.

[0063] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A method for preparing ethylene by oxidation of ethane with carbon dioxide, characterized in that: The preheated carbon dioxide and ethane mixed gas is passed into a microwave-heated multi-stage series quartz tube reactor for reaction, each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium structured catalyst, and a preheating unit and a water vapor supplement unit are connected between each stage of the quartz tube reactor; The vanadium-aluminum-titanium structured catalyst is a vanadium-aluminum-titanium composite catalyst with vanadium as an active component and a pore width of 0.5-2 mm.

2. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The steps include: 1) Building a reaction platform for preparing ethylene by oxidizing ethane with carbon dioxide, comprising: a preheater and a multi-stage series-connected microwave-heated quartz tube reactor, wherein each stage of the quartz tube reactor is loaded with a vanadium-aluminum-titanium structured catalyst, and a preheating unit and a water vapor supplementing unit are connected between each stage of the quartz tube reactor; 2) Pretreatment: preheating the mixed gas of carbon dioxide and ethane to the first reaction condition according to the reaction conditions of ethylene production by oxidation of ethane with carbon dioxide, and microwave heating the multi-stage series quartz tube reactor to the second reaction condition; 3) Catalytic reaction: a mixed gas of carbon dioxide and ethane preheated to a first reaction condition is introduced into a multi-stage series quartz tube reactor heated by microwaves to a second reaction condition for reaction. During the reaction, water vapor is added to the multi-stage series quartz tube reactor to a third reaction condition. After the reaction is completed, the ethane conversion rate and the ethylene selectivity are respectively measured.

3. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The preheated carbon dioxide and ethane mixed gas has a pressure of 0.05-0.2 MPa and a temperature of 150-250°C.

4. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The number of stages of the multi-stage series quartz tube reactor is 2-5.

5. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The microwave heating temperature of the multi-stage series quartz tube reactor is 450-500°C.

6. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The mass fraction of vanadium, an active component of the vanadium-aluminum-titanium structured catalyst, is 2%-10%.

7. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The total amount of water vapor supplemented during the reaction of the multi-stage series quartz tube reactor is 1%-5%.

8. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The multi-stage series quartz tube reactor has four stages.

9. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The mass fraction of vanadium, an active component of the vanadium-aluminum-titanium structured catalyst, is 8%.

10. The method for preparing ethylene by oxidation of ethane with carbon dioxide according to claim 1, characterized in that: The total amount of water vapor supplemented during the reaction of the multi-stage series quartz tube reactor is 2%.

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