Dehydrogenation catalyst, method for preparing and using the same, and method for preparing ethylene from ethane and carbon dioxide by oxidative dehydrogenation

Abstract

The present application provides a dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing ethylene by oxidatively dehydrogenating ethane and carbon dioxide, the catalyst comprising a carrier and a dehydrogenation active component supported on the carrier, the dehydrogenation active component comprising a first active component and a second active component, the first active component being iron, and the second active component being selected from one or more of cobalt, nickel, copper, zinc and palladium, and the dehydrogenation active component being concentratedly distributed on the surface of the carrier; and / or the reduction peak temperature of the dehydrogenation active component in a hydrogen temperature programmed reduction test is greater than the reduction peak temperature of a sample with a corresponding active component dispersion of 50%. The present application can change the distribution of the multi-metal active component on the surface of the carrier by controlling the synthesis conditions, and further adjust the selectivity of the catalyst to the oxidative dehydrogenation reaction of low-carbon alkanes.

Description

Technical Field

[0001] This invention relates to dehydrogenation catalysts, their preparation methods and applications, and a method for the oxidative dehydrogenation of ethane and carbon dioxide to produce ethylene. Background Technology

[0002] Low-carbon alkanes (C2-C4) are an important component of shale gas, accounting for up to 15% of the volume in the richest areas. The main reactions between low-carbon alkanes and carbon dioxide (CO2) are oxidative dehydrogenation and dry reforming, with the main products being ethylene and syngas, which have high economic and social value.

[0003] Studies have shown that the selectivity of the reaction products of low-carbon alkanes and carbon dioxide is closely related to the reaction phase interface, and the distribution of active components on the support surface can be effectively controlled to control the reaction products (PNAS2018,115,8278).

[0004] Supported catalysts are catalysts in which the active component and co-catalyst are uniformly dispersed and supported on a selected support. The distribution of the active component on the support surface has a significant impact on catalytic reactivity. There is a strong metal-support interaction between the transition metal active component and the variable valence oxide support. The activity and selectivity of the catalytic reaction can be controlled by changing the strength of the interaction between the active component and the support and the interfacial density. Summary of the Invention

[0005] The purpose of this invention is to provide a dehydrogenation catalyst in which the dehydrogenation active components are concentrated on the surface of a support, as well as its preparation method and application.

[0006] According to a first aspect of the present invention, the present invention provides a dehydrogenation catalyst comprising a support and a dehydrogenation active component supported on the support, the dehydrogenation active component comprising a first active component and a second active component, the first active component being iron, and the second active component being selected from one or more of cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and palladium (Pd), the dehydrogenation active component being concentratedly distributed on the surface of the support; and / or the reduction peak temperature of the dehydrogenation active component in a hydrogen temperature-programmed reduction test is greater than the reduction peak temperature of a sample with a corresponding active component dispersion of 50%.

[0007] According to a second aspect of the present invention, the present invention provides a method for preparing the dehydrogenation catalyst of the present invention, wherein the method comprises: impregnating and contacting a support source with a solution containing a first active component source and a second active component source under equal volume impregnation conditions, wherein the polarity or weighted polarity of the solution is strongly polar in molar fractions.

[0008] According to a third aspect of the present invention, the present invention provides the application of the catalyst described herein in dehydrogenation, preferably in oxidative dehydrogenation.

[0009] According to a fourth aspect of the present invention, the present invention provides a method for preparing ethylene by oxidative dehydrogenation of ethane and carbon dioxide, the method comprising: reducing a catalyst, wherein ethane and carbon dioxide are reacted with a reduced catalyst, wherein the catalyst is the catalyst described in the present invention.

[0010] The catalyst preparation method of the present invention can adjust the selectivity of the catalyst for the oxidative dehydrogenation reaction of low-carbon alkanes by changing the distribution of multi-metal active components on the support surface through the control of synthesis conditions.

[0011] The catalyst preparation method of the present invention, by controlling the polarity of the mixed solvent in a one-step equal-volume co-impregnation, can obtain a surface structure with controllable distribution of active components.

[0012] The catalytic selectivity regulation of the catalyst in this invention is the result of metal-support interaction.

[0013] The catalyst preparation method of this invention is simple, has little environmental impact, and is suitable for large-scale production. Attached Figure Description

[0014] The accompanying drawings provide a further understanding of the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0015] Figure 1 The images shown are scanning transmission microscopy (STEM) images (1a) and energy dispersive X-ray spectroscopy (EDS mapping) images (1b-1f) of the active metals of catalyst A in Example 1, which are concentrated on the surface of the support. Among them, 1b is a stacked distribution map of each element, 1c is a Ce element distribution map, 1d is an Al element distribution map, 1e is an Fe element distribution map, and 1f is a Ni element distribution map.

[0016] Figure 2 The images show the hydrogen-programmed temperature reduction (H2-TPR) images of the active metals of catalyst A in Example 1 and catalyst G in Comparative Example 1 on the support surface. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] This invention provides a dehydrogenation catalyst comprising a support and a dehydrogenation active component loaded on the support. The dehydrogenation active component comprises a first active component and a second active component. The first active component is iron, and the second active component is selected from one or more of cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and palladium (Pd). The dehydrogenation active component is concentrated on the surface of the support; and / or the reduction peak temperature of the dehydrogenation active component in a hydrogen temperature-programmed reduction test is greater than the reduction peak temperature of a sample with a corresponding active component dispersion of 50%. The catalyst of this invention has the advantages of high reactivity, good stability, simple synthesis method, and environmental friendliness.

[0019] In this invention, scanning transmission microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS mapping) images show that the dehydrogenation active components are concentrated on the surface of the support.

[0020] In this invention, scanning transmission microscopy (STEM) images and energy-dispersive X-ray spectroscopy (EDSmapping) images are obtained using a spherical aberration-corrected transmission electron microscope (TEM) with an accelerating voltage of 200 kV. An ethanol solution containing the sample to be tested is dropped onto a copper grid covered with an ultrathin carbon film and allowed to air dry naturally, serving as the sample for TEM characterization.

[0021] In this invention, the standard for hydrogen temperature-programmed reduction test is to test the sample under a 10% volume fraction hydrogen / argon mixed atmosphere with a space velocity of 50 mL / min and a heating rate of 10 °C / min.

[0022] According to a preferred embodiment of the present invention, the second active component element is selected from one or more of cobalt, nickel, copper, zinc and palladium.

[0023] In this invention, the ratio of the catalyst support and the active component can be flexibly adjusted, and can be selected according to needs. According to a preferred embodiment of this invention, the catalyst comprises 90-99.5 parts of support and 0.5-10 parts of dehydrogenation active component based on oxides, based on the mass fraction of the catalyst.

[0024] According to a preferred embodiment of the present invention, the molar ratio of the first active component to the second active component is 1:0.2-1, preferably 1:0.2-0.6, based on elemental composition; thereby the catalyst has the advantages of high stability and long lifespan.

[0025] According to a preferred embodiment of the present invention, the reduction peak temperature of the active metal on the catalyst surface in the hydrogen programmed temperature reduction test is greater than 210°C; this indicates that the active component is concentrated on the support surface, thereby giving the catalyst the advantage of high selectivity.

[0026] According to a preferred embodiment of the present invention, scanning transmission microscopy (STEM) images and energy-dispersive X-ray spectroscopy (EDS mapping) images of the active metal dispersed on the surface of the support show a dispersion of 10-36% for the dehydrogenation active component. In this invention, the methods for calculating the dispersion include chemisorption and transmission electron microscopy.

[0027] In this invention, the range of carrier types is relatively wide, and commonly used carriers can all be used in this invention. According to a preferred embodiment of this invention, the carrier is selected from one or more oxides or composite oxides formed from titanium, cerium, aluminum, magnesium, zirconium, and silicon.

[0028] Catalysts possessing the aforementioned properties of this invention can all be used in this invention, and there are no special requirements for their preparation methods. According to a preferred embodiment of this invention, this invention provides a method for preparing a catalyst, the method comprising: impregnating and contacting a support source with a solution containing a first active component source and a second active component source under equal volume impregnation conditions, wherein the polarity or weighted polarity of the solution is strong polarity in molar fractions.

[0029] In this invention, the polarity, or weighted polarity in mole fractions, refers to the sum of the product of the polarity of the corresponding pure solvent and its mole fraction. This is well known to those skilled in the art, and will not be described in detail here.

[0030] By using the aforementioned method to prepare catalysts, the distribution of multi-metallic active components on the support surface can be altered by controlling the preparation conditions, thereby adjusting the selectivity of the catalyst for oxidative dehydrogenation.

[0031] The catalytic selectivity regulation of the catalyst in this invention is the result of metal-support interaction.

[0032] The catalyst preparation method of this invention is simple, has little environmental impact, and is suitable for large-scale production.

[0033] The method of this invention, by controlling the equal-volume impregnation process and the polarity of the impregnation solvent during the impregnation of the dehydrogenation active component, can effectively regulate the surface structure of the catalyst supported on the dehydrogenation active component, thereby obtaining a high-performance oxidative dehydrogenation catalyst. The catalyst synthesis method used in this invention is versatile and applicable to various supported catalysts with different compositions.

[0034] According to a preferred embodiment of the present invention, the polarity of the solvent in the solution is in the range of 6.2 to 10.1, preferably 7.1 to 10.1. According to the catalyst preparation method of the present invention, by controlling the polarity of the solvent in the one-step equal-volume co-impregnation, a surface structure with controllable distribution of active components is obtained.

[0035] Solvents with the aforementioned properties can be used in this invention. According to a preferred embodiment of this invention, the solvent is selected from one or more of water, methanol, ethanol, ethylene glycol, isopropanol, acetone, formic acid, acetic acid, ethyl acetate, N,N-dimethylformamide, acetonitrile, cyclohexane, and petroleum ether, preferably one or more of water, ethylene glycol, acetone, and N,N-dimethylformamide.

[0036] According to a preferred embodiment of the present invention, the method includes:

[0037] The first active component source and the second active component source are dissolved in a polar solvent in a certain proportion. The carrier source is added to the resulting solution and dispersed evenly for the equal-volume impregnation. Then the solution is dried and calcined.

[0038] In this invention, the source of the first active component has a wide range of options, and commonly used compounds can be used in this invention. For this invention, it is preferred to select at least one of ferrous ammonium sulfate (II), ferrous sulfate (II), ferric sulfate (III), ferric nitrate (III), ferrous oxalate (II), ferrous chloride (II), and ferric chloride (III).

[0039] In this invention, the source of the second active component has a wide range of options, and commonly used compounds can be used in this invention. For this invention, it is preferred to select at least one of chloride, bromide, nitrate, sulfate, carbonate, acetate, oxalate and acetylacetonate.

[0040] In this invention, there are no special requirements for the drying conditions; they can be carried out according to conventional drying steps and conditions. According to a preferred embodiment of this invention, the drying conditions include drying at 60–150°C for 4–24 hours, preferably at 80–120°C for 8–15 hours.

[0041] In this invention, there are no special requirements for the roasting conditions. The roasting can be carried out according to conventional roasting steps and conditions. According to a preferred embodiment of this invention, the roasting conditions include: a roasting temperature of 350-600℃, preferably 400-500℃; and / or a roasting time of 2-8h, preferably 4-6h.

[0042] The catalyst of this invention is particularly suitable for use in the field of dehydrogenation, especially in the field of oxidative dehydrogenation.

[0043] This invention provides the application of the catalyst described herein in dehydrogenation, preferably in oxidative dehydrogenation.

[0044] According to the present invention, a method for preparing ethylene by oxidative dehydrogenation of ethane and carbon dioxide is provided. The method includes: reducing a catalyst, wherein ethane and carbon dioxide are reacted with the reduced catalyst, wherein the catalyst is the catalyst described in the present invention.

[0045] In this invention, there are no special requirements for the contact reaction conditions, which can be adjusted as needed.

[0046] In this invention, there are no special requirements for the method of reducing the catalyst, and it will not be described in detail here.

[0047] According to a preferred embodiment of the present invention, the method preferably includes: at 400–600°C before the contact reaction, 40–60 mL·min -1 The mixture is reduced under a reducing atmosphere of H2 for 0.5–2 hours, followed by the introduction of ethane and carbon dioxide as feedstock gases for a contact reaction. Preferred contact conditions include: feedstock gas composition of C2H6:CO2:N2 = 0.5–1:0.5–1:0–2, and a total flow rate of 60–120 mL / min. -1 The reaction is carried out under normal pressure at a temperature of 650–750 °C.

[0048] According to a preferred embodiment of the present invention, the method preferably includes:

[0049] (1) The catalyst is reduced in a hydrogen atmosphere at a reduction temperature of 350-700℃, preferably 400-600℃, and for a reduction time of 0.5-4h, preferably 0.5-2h.

[0050] (2) The reaction is carried out in a fixed-bed reactor at atmospheric pressure, with a reaction temperature of 550–750℃, preferably 650–750℃. The feed gas is a mixture of ethane, carbon dioxide, and nitrogen, with a total flow rate of 5–120 mL·min. -1 Preferably 60-120 mL·min -1 The volume fraction of ethane is 25-50%, the volume fraction of carbon dioxide is 25-50%, and the remainder is nitrogen balance gas.

[0051] According to a preferred embodiment of the present invention, an ethane and carbon dioxide oxidative dehydrogenation catalyst is provided, comprising iron and transition metal active components, wherein the transition metal active components specifically include one or more selected from cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and palladium (Pd); the support is a variable-valence oxide or composite oxide, specifically including at least one selected from titanium oxide (TiO2), cerium oxide (CeO2), and composite oxides formed with aluminum oxide (Al2O3), magnesium oxide (MgO), zirconium oxide (ZrO2), and silicon oxide (SiO2); the reduction peak temperature of the active metal on the catalyst surface in a hydrogen programmed temperature reduction test is greater than the reduction peak temperature of the sample with a corresponding active component dispersion of 50%; scanning transmission microscopy (STEM) and energy dispersive X-ray spectroscopy (EDSmapping) images showing that the iron-nickel active components are concentrated on the surface of the cerium-aluminum composite oxide support, preferably with an active component dispersion of 10-36%.

[0052] The present invention will be further illustrated by the following embodiments, but the application of the present invention is not limited to these embodiments.

[0053] The calculation method for ethane conversion rate is: (ethane inlet velocity - ethane outlet velocity) ÷ ethane inlet velocity × 100%.

[0054] The calculation method for ethylene selectivity is: ethylene product flow rate ÷ (ethane inlet flow rate - ethane outlet flow rate) × 100%.

[0055] Figure 1 The images shown are scanning transmission microscopy (STEM) images (1a) and energy dispersive X-ray spectroscopy (EDS mapping) images (1b-1f) of the active metals of catalyst A in Example 1, which are concentrated on the surface of the support. Among them, 1b is a stacked distribution map of each element, 1c is a Ce element distribution map, 1d is an Al element distribution map, 1e is an Fe element distribution map, and 1f is a Ni element distribution map.

[0056] Figure 2 Images showing the hydrogen temperature-programmed reduction (H2-TPR) of the active metals on the support surface of catalyst A in Example 1 and catalyst G in Comparative Example 1, generated by... Figure 2 It can be seen that the reduction peak temperature of the surface active metal of catalyst A in the hydrogen programmed temperature reduction test is higher than that of the contrast agent catalyst G.

[0057] Example 1

[0058] Dissolve 0.20 mmol of ferric nitrate and 0.04 mmol of nickel nitrate in an appropriate amount of ethylene glycol-water mixed solvent with a solvent weighted polarity of 10.1 (where the molar fraction of ethylene glycol is 3.0%), and add 0.838 g of cerium-aluminum composite oxide (CeAlO). x Catalyst A was obtained by impregnating the support with an equal volume for 1 hour, drying at 80°C for 15 hours, and calcining at 400°C for 6 hours, wherein the dispersion of the iron-nickel active component was 10%. The metal content in catalyst A was determined by ICP-AES: the molar ratio of iron to nickel in catalyst A was 1:0.2, expressed as a molar percentage. Figure 1 The STEM image shows that the iron-nickel active components (1e, 1f) of catalyst A are concentrated on the surface of the cerium-aluminum composite oxide support (1c, 1d) in the region shown in 1a. 1b is a stacked diagram of the elemental distribution in this region. Figure 2 The image shows the H2-TPR image of catalyst A, whose reduction peak temperature is higher than that of the sample with an active component dispersion of 50%. Figure 1 The images show scanning transmission microscopy (STEM) images (1a) and energy dispersive X-ray spectral surface scanning (EDS mapping) images (1b-1f) of active metals concentrated on the surface of the support. In 1b, the distribution of each element is stacked, 1c is the distribution of Ce, 1d is the distribution of Al, 1e is the distribution of Fe, and 1f is the distribution of Ni.

[0059] The reactivity of catalyst A with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1 The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a temperature of 650℃ for 2 hours. The ethane conversion rate of catalyst A was 32.1%, the ethylene selectivity was 94.6%, and the main product was ethylene.

[0060] After 12 hours of reaction, the ethane conversion rate was 29.5%, the ethylene selectivity was 95.3%, and the main product was ethylene.

[0061] Example 2

[0062] Dissolve 0.10 mmol of ferrous sulfate and 0.04 mmol of copper sulfate in an appropriate amount of ethylene glycol-water mixed solvent with a solvent weighted polarity of 8.6 (where the molar fraction of ethylene glycol is 48.5%), and add 0.938 g of titanium-magnesium composite oxide (MgTiO). xCatalyst B was obtained by impregnating the support with an equal volume for 1 hour, drying at 100℃ for 12 hours, and calcining at 450℃ for 5 hours. The dispersion of the iron and copper active components in catalyst B was 17%, and the iron and copper active components were concentrated on the surface of the titanium-magnesium composite oxide support. The proportion of metals in catalyst B was determined by ICP-AES: the molar ratio of iron to copper in catalyst B was 1:0.4 (molar percentage).

[0063] The reactivity of catalyst B with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 450 °C for 50 mL / min. -1 The reaction was carried out under a H2 atmosphere for 1 hour, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:1. The reaction was conducted at atmospheric pressure and 700℃ for 2 hours. The ethane conversion rate of catalyst B was 40.8%, the ethylene selectivity was 85.2%, and the main product was ethylene.

[0064] After 12 hours of reaction, the ethane conversion rate was 36.4%, the ethylene selectivity was 90.2%, and the main product was ethylene.

[0065] Example 3

[0066] 0.03 mmol of ferric chloride and 0.02 mmol of palladium acetylacetonate were dissolved in an appropriate amount of N,N-dimethylformamide-water mixed solvent with a solvent weighted polarity of 7.1 (where the molar fraction of N,N-dimethylformamide was 81.6%), and 1.112 g of cerium-zirconium composite oxide (CeZrO) was added. x Catalyst C was obtained by impregnating the support with an equal volume for 1 hour, drying at 120℃ for 8 hours, and calcining at 500℃ for 4 hours. The dispersion of the iron-palladium active component in the catalyst C was 25%, and the iron-palladium active component was concentrated on the surface of the cerium-zirconium composite oxide support. The proportion of metals in catalyst C was determined by ICP-AES: the molar ratio of iron to palladium in catalyst C was 1.5:1 (molar percentage).

[0067] The reactivity of catalyst C with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 500 °C for 40 mL / min. -1 The reaction was carried out under a H2 atmosphere for 0.5 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:0. The reaction was conducted at atmospheric pressure and a reaction temperature of 750℃ for 2 hours. The ethane conversion rate of catalyst C was 44.2%, the ethylene selectivity was 80.6%, and the main product was ethylene.

[0068] After 12 hours of reaction, the ethane conversion rate was 39.1%, the ethylene selectivity was 87.3%, and the main product was ethylene.

[0069] Example 4

[0070] Dissolve 0.20 mmol of ferric nitrate and 0.04 mmol of nickel nitrate in a suitable amount of acetone-water mixed solvent with a solvent weighted polarity of 6.2 (where the molar fraction of acetone is 83.3%), and add 1.090 g of cerium-aluminum composite oxide (CeAlO). x Catalyst D was obtained by impregnating the support with an equal volume for 1 hour, drying at 80℃ for 15 hours, and calcining at 400℃ for 6 hours. The dispersion of the iron-nickel active component was 36%, and the iron-nickel active component was concentrated on the surface of the cerium-aluminum composite oxide support. The proportion of metals in catalyst D was determined by ICP-AES: the molar ratio of iron to nickel in catalyst D was 1:0.2 (molar percentage).

[0071] The reactivity of catalyst D with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1 The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a reaction temperature of 650℃ for 2 hours. The ethane conversion rate of catalyst D was 30.5%, the ethylene selectivity was 74.9%, and the main product was ethylene.

[0072] After 12 hours of reaction, the ethane conversion rate was 27.2%, the ethylene selectivity was 76.4%, and the main product was ethylene.

[0073] Example 5

[0074] Dissolve 0.20 mmol of ferric nitrate and 0.20 mmol of nickel nitrate in an appropriate amount of ethylene glycol-water mixed solvent with a solvent weighted polarity of 10.1 (where the molar fraction of ethylene glycol is 3.0%), and add 1.125 g of cerium-aluminum composite oxide (CeAlO). x Catalyst E was obtained by impregnating the support with an equal volume for 1 hour, drying at 80℃ for 15 hours, and calcining at 400℃ for 6 hours. The dispersion of the iron-nickel active component was 31%, and the iron-nickel active component was concentrated on the surface of the cerium-aluminum composite oxide support. The proportion of metals in catalyst E was determined by ICP-AES: the molar ratio of iron to nickel in catalyst E was 1:1 (molar percentage).

[0075] The reactivity of catalyst E with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a reaction temperature of 650℃ for 2 hours. The ethane conversion rate of catalyst E was 31.5%, the ethylene selectivity was 77.3%, and the main product was ethylene.

[0076] After 12 hours of reaction, the ethane conversion rate was 28.3%, the ethylene selectivity was 78.6%, and the main product was ethylene.

[0077] Example 6

[0078] Dissolve 0.60 mmol of ferric nitrate and 0.12 mmol of nickel nitrate in an appropriate amount of ethylene glycol-water mixed solvent with a solvent weighted polarity of 10.1 (where the molar fraction of ethylene glycol is 3.0%), and add 0.943 g of cerium-aluminum composite oxide (CeAlO). x Catalyst F was obtained by impregnating the support with an equal volume for 1 hour, drying at 80℃ for 15 hours, and calcining at 400℃ for 6 hours. The dispersion of the iron-nickel active component was 28%, and the iron-nickel active component was concentrated on the surface of the cerium-aluminum composite oxide support. The proportion of metals in catalyst F was determined by ICP-AES: the molar ratio of iron to nickel in catalyst F was 1:0.2 (molar percentage).

[0079] The reactivity of catalyst F with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1 The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a reaction temperature of 650℃ for 2 hours. The ethane conversion rate of catalyst F was 32.0%, the ethylene selectivity was 78.4%, and the main product was ethylene.

[0080] After 12 hours of reaction, the ethane conversion rate was 30.5%, the ethylene selectivity was 81.1%, and the main product was ethylene.

[0081] Comparative Example 1

[0082] Dissolve 0.20 mmol of ferric nitrate and 0.04 mmol of nickel nitrate in an appropriate amount of ethanol-ethylene glycol mixed solvent with a solvent weighted polarity of 5.7 (where the molar fraction of ethanol is 46.2%), and add 1.090 g of cerium-aluminum composite oxide (CeAlO). xCatalyst G was obtained by impregnating the support with an equal volume for 1 hour, drying at 80℃ for 15 hours, and calcining at 400℃ for 6 hours. The dispersion of the iron-nickel active component was 50%, and the iron-nickel active component was dispersed on the surface of the cerium-aluminum composite oxide support. The proportion of metals in catalyst G was determined by ICP-AES: the molar ratio of iron to nickel in catalyst G was 1:0.2 (molar percentage).

[0083] The reactivity of catalyst G with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1 The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a temperature of 650℃ for 2 hours. The catalyst G achieved an ethane conversion rate of 27.1% and a CO selectivity of 65.0%, with syngas as the main product.

[0084] After 12 hours of reaction, the ethane conversion rate was 21.9%, the CO selectivity was 62.1%, and the main product was syngas.

[0085] Comparative Example 2

[0086] Dissolve 0.20 mmol of ferric nitrate and 0.04 mmol of nickel nitrate in 10 mL of water with a polarity of 10.2. Then, using an excess impregnation method, add 1.090 g of cerium-aluminum composite oxide (CeAlO₂). x Catalyst H was obtained by impregnating the support for 1 hour, drying at 80℃ for 15 hours, and calcining at 400℃ for 6 hours. The iron-nickel active component had a dispersion of 54% and was dispersed on the surface of the cerium-aluminum composite oxide support. The metal ratio in catalyst H was determined by ICP-AES: the molar ratio of iron to nickel in catalyst H was 1:0.2 (molar percentage). The H2-TPR reduction peak temperature of catalyst H was lower than that of the sample with a 50% dispersion of active components.

[0087] The reactivity of catalyst H with ethane and carbon dioxide was tested in a fixed-bed atmospheric pressure microreactor. The catalyst dosage was 100 mg, and the reaction was initially carried out at 400 °C for 60 mL / min. -1 The reaction was carried out under a H2 atmosphere for 2 hours, followed by the introduction of a feed gas with a composition of C2H6:CO2:N2 = 1:1:2. The reaction was conducted at atmospheric pressure and a temperature of 650℃ for 2 hours. The ethane conversion rate of catalyst H was 28.8%, the CO selectivity was 54.5%, and the main product was syngas.

[0088] After 12 hours of reaction, the ethane conversion rate was 19.5%, the CO selectivity was 51.7%, and the main product was syngas.

[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A dehydrogenation catalyst, characterized in that, The catalyst contains a support and a dehydrogenation active component supported on the support. The dehydrogenation active component contains a first active component and a second active component. The first active component is iron, and the second active component is selected from one or more of cobalt, nickel, copper, zinc, and palladium. The dehydrogenation active component is concentrated on the surface of the support. The reduction peak temperature of the dehydrogenation active component in the hydrogen temperature-programmed reduction test is higher than the reduction peak temperature of the sample with a corresponding active component dispersion of 50%. The molar ratio of the first active component to the second active component is 1:0.2-0.6 based on elemental composition; the reduction peak temperature of the active metal on the catalyst surface is greater than 210℃ in the hydrogen programmed temperature reduction test; and the dispersion of the dehydrogenation active component is 10-25%.

2. The catalyst according to claim 1, wherein, The catalyst comprises, by mass fraction, 90-99.5 parts of support and 0.5-10 parts of dehydrogenation active component based on oxides; and / or The carrier is selected from one or more oxides or composite oxides formed from titanium, cerium, aluminum, magnesium, zirconium and silicon.

3. The method for preparing the dehydrogenation catalyst according to claim 1 or 2, wherein, The method includes: Under equal-volume impregnation conditions, the carrier source is impregnated and contacted with a solution containing a first active component source and a second active component source, wherein the polarity of the solvent in the solution is in the range of 7.1 to 10.

1.

4. The preparation method according to claim 3, wherein, The solvent is selected from one or more of water, methanol, ethanol, ethylene glycol, isopropanol, acetone, formic acid, acetic acid, ethyl acetate, N,N-dimethylformamide, acetonitrile, cyclohexane, and petroleum ether.

5. The preparation method according to claim 4, wherein, The solvent is selected from one or more of water, ethylene glycol, acetone, and N,N-dimethylformamide.

6. The preparation method according to claim 3, wherein, The method includes: The first active component source and the second active component source are dissolved in a polar solvent in a certain proportion. The carrier source is added to the resulting solution and dispersed evenly for the equal-volume impregnation. Then the solution is dried and calcined.

7. The preparation method according to claim 6, wherein, The first active component source is selected from at least one of ferrous ammonium sulfate, ferrous sulfate, ferric sulfate, ferric nitrate, ferrous oxalate, ferrous chloride, and ferric chloride; and / or The second active component source is selected from at least one of chloride, bromide, nitrate, sulfate, carbonate, acetate, oxalate and acetylacetone salt.

8. The preparation method according to claim 6, wherein, The drying conditions include drying at 60~150°C for 4~24 h; The calcination conditions include: calcination temperature of 350~600°C; and / or calcination time of 2~8 h.

9. The preparation method according to claim 8, wherein, The drying conditions include drying at 80~120°C for 8~15 h; The calcination conditions include: a calcination temperature of 400-500°C; and / or a calcination time of 4-6 h.

10. The use of the catalyst according to claim 1 or 2 in dehydrogenation.

11. The application according to claim 10, wherein, The application mentioned is in dehydrogenation, specifically in oxidative dehydrogenation.

12. A method for preparing ethylene by oxidative dehydrogenation of ethane and carbon dioxide, characterized in that, The method includes: reducing a catalyst by contacting ethane and carbon dioxide with the reduced catalyst, wherein the catalyst is the catalyst according to claim 1 or 2.

13. The method according to claim 12, wherein, The method includes: pre-contact reaction at 400–600°C, 40–60 mL / min. -1 The mixture is reduced under a H2 reducing atmosphere for 0.5 to 2 hours, and then the raw material gas ethane and carbon dioxide are introduced for contact reaction.

14. The method according to claim 13, wherein, Contact conditions include: feed gas composition of C2H6:CO2:N2 = 0.5~1:0.5~1:0~2, and total flow rate of 60~120 mL·min. -1 The reaction is carried out under normal pressure and at a temperature of 650~750°C.

Images