Dehydrogenation catalyst, its preparation method and application and method for preparing butadiene by butene oxidative dehydrogenation under low water ratio

Abstract

The present application relates to a dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing butadiene by butene oxidative dehydrogenation under a low water ratio condition, and provides a dehydrogenation catalyst, which comprises a spinel phase, an iron oxide crystal phase, a silicon oxide crystal phase, a nitride and a transition metal oxide; the present application increases the surface hydroxyl group density of the ferrite in the ferrite with a spinel structure by adding a nitride and other transition metal oxide additives for the first time, improves the adsorption and coverage of water molecules on the surface of the catalyst, and thus solves the problem of reduced stability of the catalyst under a low water ratio condition.

Description

Technical Field

[0001] This invention relates to dehydrogenation catalysts, their preparation methods and applications, and a method for the oxidative dehydrogenation of butene to butadiene under low water ratio conditions. Background Technology

[0002] Butadiene is a basic raw material in the petrochemical industry and can be copolymerized with various compounds to produce various synthetic rubbers and resins. Currently, butadiene is mainly produced through two methods: ethylene production via refinery steam cracking and C4 extraction / separation, and butadiene oxidation. Butadiene oxidative dehydrogenation is a process targeting butadiene as the product, converting butadiene used for civilian fuels into high-value-added butadiene. This production technology is an important supplement to C4 extraction / separation technology.

[0003] Various catalytic systems, such as the Mo-Bi system, Sn-P-Li system, and Feate system, can be used for the oxidative dehydrogenation of butene to produce butadiene. While the Mo-Bi system has a low water-to-olefin ratio (water-to-olefin ratio) of 6–8, it exhibits low selectivity and produces a large amount of organic oxygen-containing byproducts. The Sn-P-Li system has high activity, but its operating conditions are demanding, requiring a water-to-olefin ratio exceeding 30 and resulting in very high energy consumption. Iron-based catalysts are currently the most widely used catalysts for the oxidative dehydrogenation of butene. Their advantages include good stability and relatively few oxidation byproducts; however, the water-to-olefin ratio is 12–16, leading to high energy consumption, large wastewater volumes, and high production costs.

[0004] Since its invention (USP3270080), iron-based butene oxidative dehydrogenation catalysts have undergone numerous improvements, resulting in continuously enhanced performance. Using a foamed silicon carbide structured support to support ferrate catalytic active components (CN104001533B) can enhance mass and heat transfer in the oxidative dehydrogenation reaction at a water ratio of 6. CN107973690A discloses a molybdenum-bismuth system oxidative dehydrogenation catalyst that can operate at a lower water ratio. CN111054353A and CN107537530B disclose a ferrate system low-water-ratio oxidative dehydrogenation catalyst with good stability. Adding vanadium-containing heteropolyacids can improve the dehydrogenation performance of molybdenum-bismuth catalysts (CN115487868B) at water ratios of 2-8. However, to date, the industrial butene oxidative dehydrogenation reaction still requires a large amount of steam as a medium. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of reduced stability of existing iron oxide catalysts in the process of butene oxidative dehydrogenation to butadiene production under low water ratio conditions. This invention provides a dehydrogenation catalyst and its preparation method. Compared with other catalysts, this catalyst has a higher surface hydroxyl content, which can effectively improve the operational stability of the dehydrogenation catalyst in butene oxidative dehydrogenation to butadiene production under low water ratio conditions.

[0006] To achieve the above objectives, the present invention provides a dehydrogenation catalyst comprising: a spinel phase, an iron oxide phase, a silicon oxide phase, a nitride, and a transition metal oxide.

[0007] The second aspect of the present invention provides a method for preparing the catalyst of the present invention, the method comprising: (1) co-precipitating an Fe source, an inorganic salt containing a high molecular weight organic compound required to form a spinel phase, and an alkaline source, separating the solid and liquid phases, washing the mixture, and dispersing it in a solvent to form a first slurry; (2) contacting a nitrogen source, a transition metal source, and a silicon source in a solvent, grinding them into a colloidal solution to form a second slurry; and (3) contacting the second slurry with the first slurry, shaping the mixture, and calcining it.

[0008] A third aspect of the present invention provides the application of the catalyst described herein in the preparation of conjugated dienes from monoolefins.

[0009] A fourth aspect of the present invention provides a method for the oxidative dehydrogenation of butene to butadiene suitable for low water ratio conditions. The method includes: reacting a diluent, an oxidant, butene, and a catalyst in a contact reaction; the catalyst includes the catalyst described in the present invention.

[0010] Through the above technical solution, the present invention has the following beneficial effects:

[0011] This invention provides a dehydrogenation catalyst comprising: a spinel phase, an iron oxide phase, a silicon oxide phase, nitrides, and transition metal oxides; thereby improving the adsorption and coverage of water molecules on the catalyst surface and solving the problem of reduced catalyst stability under low water ratio conditions. Detailed Implementation

[0012] 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.

[0013] The present invention provides a dehydrogenation catalyst comprising: spinel phase, iron oxide phase, silicon oxide phase, nitride and transition metal oxide.

[0014] The dehydrogenation catalyst of this invention has a high surface hydroxyl density, which is beneficial to improving the stability of iron-based oxidative dehydrogenation reaction under low water ratio conditions. It is used in the preparation of conjugated dienes from monoolefins, and has achieved good stability, especially in the preparation of butadiene.

[0015] According to a preferred embodiment of the present invention, the content of spinel phase is 40-60 wt%, preferably 43-55 wt%, based on 100 wt% of catalyst.

[0016] According to a preferred embodiment of the present invention, the content of iron oxide crystalline phase is 5-10 wt%, preferably 6-8 wt%, based on 100 wt% of catalyst.

[0017] According to a preferred embodiment of the present invention, the content of the silicon oxide crystalline phase is 30-50 wt%, preferably 35-45 wt%, based on 100 wt% of the catalyst.

[0018] According to a preferred embodiment of the present invention, the content of nitride is 0.5-5 wt%, preferably 1-3 wt%, based on 100 wt% of catalyst.

[0019] According to a preferred embodiment of the present invention, the content of transition metal oxide is 0.1-8 wt%, preferably 2-5 wt%, based on 100 wt% of catalyst.

[0020] By adopting the aforementioned preferred embodiments, the surface hydroxyl density of the catalyst can be further increased, thereby enhancing the catalyst's operational stability under low water ratio conditions.

[0021] In this invention, the range of nitrides is relatively wide. According to a preferred embodiment of the invention, the nitride is selected from at least one of boron nitride, zirconium nitride, chromium nitride, magnesium nitride, iron nitride, and titanium nitride, preferably at least one of zirconium nitride, chromium nitride, and titanium nitride. By adopting the aforementioned preferred embodiment, the density of surface hydroxyl groups can be further increased.

[0022] In this invention, the transition metal oxide can be selected from a wide range. According to a preferred embodiment of the invention, the transition metal oxide is selected from at least one of titanium dioxide, zirconium oxide, and alumina, preferably titanium dioxide and / or zirconium oxide. By employing the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0023] In this invention, the surface hydroxyl content of the catalyst can be selected from a wide range. According to a preferred embodiment of this invention, the surface hydroxyl content of the catalyst is 60-500 μmol / g, preferably 100-400 μmol / g.

[0024] In this invention, the pore volume of the catalyst is not particularly required. According to a preferred embodiment of the invention, the pore volume of the catalyst is 0.2-6 mL / g, preferably 2-2.5 mL / g. By adopting the aforementioned preferred embodiment, the mass and heat transfer effect between reactants and products can be further improved while ensuring a certain mechanical strength of the catalyst particles.

[0025] In this invention, the average pore size of the catalyst is not particularly required. According to a preferred embodiment of the invention, the average pore size of the catalyst is 1-90 nm, preferably 20-25 nm. By adopting the aforementioned preferred embodiment, it is possible to further improve and reduce the mass transfer resistance of the reactants while ensuring a certain level of mechanical strength.

[0026] In this invention, the specific surface area of ​​the catalyst is not particularly required. However, according to a preferred embodiment of this invention, the specific surface area of ​​the catalyst is 1-80 m². 2 / g, preferably 22-28m 2 / g. By adopting the aforementioned preferred embodiments, the activity of the catalyst can be further improved while ensuring a certain level of mechanical strength.

[0027] In this invention, there are no special requirements for the particle size of the catalyst. For this invention, the average particle size of the catalyst is preferably 20-160 μm, and more preferably 80-120 μm.

[0028] In this invention, the spinel structure has no special requirements. According to a preferred embodiment of the invention, the spinel structure satisfies the chemical formula: AFe₂O₄, where A is a divalent metal element selected from at least one of Ca, Mn, Co, Ni, Zn, Cd, Hg, Mg, and Sn. The examples use the divalent metal Zn as an example, but this does not limit the scope of the invention. By adopting the aforementioned preferred embodiment, the catalyst activity can be further improved.

[0029] All dehydrogenation catalysts with the aforementioned characteristics can be used in this invention, and there are no special requirements for their preparation methods. In this invention, a method for preparing a dehydrogenation catalyst is provided, which includes: (1) co-precipitating an Fe source, an inorganic salt containing the inorganic salt required to form the spinel phase, a high molecular weight organic compound, and an alkaline source, aging, separating the solid and liquid, washing, and dispersing them in a solvent to form a first slurry; (2) contacting a nitrogen source, a transition metal source, and a silicon source in a solvent, grinding them into a colloidal solution to form a second slurry; (3) contacting the second slurry with the first slurry, shaping, and calcining.

[0030] In step (1) of this invention, the inorganic salts and high molecular weight organic compounds required to form the spinel phase can be dissolved in deionized water first, and then co-precipitated with an alkaline source. The amount of deionized water required for dissolution is not limited and can be adjusted according to experimental conditions, as long as the purpose of dissolution is achieved.

[0031] In this invention, the washing operation in step (1) involves washing the solid-liquid separated materials with deionized water, and then dispersing them into a slurry with deionized water for later use. The amount of deionized water and the number of washing cycles are not limited and can be adjusted according to actual operation. In the example, the slurry obtained from precipitation is filtered, washed twice with 800ml of deionized water, and then dispersed into a slurry with 200ml of deionized water for later use as an example, but this does not limit the scope of this invention.

[0032] In this invention, the range of silicon sources is relatively wide, and it can be any conventional silicon source in the art. Any raw material capable of providing silica after calcination is suitable for this invention, such as silica gel, silica sol, or organosilicon sources. According to a preferred embodiment of this invention, the silicon source is silica sol, preferably with an average particle size of 20-200 nm, more preferably 80-160 nm, and a solid content of 30-38 wt%. The example uses silica sol (38 wt%) with a particle size of 95 nm as an example, but this does not limit the scope of the invention. By adopting the aforementioned preferred embodiment, the hydroxyl density on the catalyst surface and the uniform distribution of the catalytically active components in the catalyst can be further increased.

[0033] According to a preferred embodiment of the present invention, the nitrogen source is selected from at least one of boron nitride, zirconium nitride, chromium nitride, magnesium nitride, iron nitride, and titanium nitride, preferably at least one of chromium nitride and titanium nitride.

[0034] According to a preferred embodiment of the present invention, the transition metal source is selected from at least one of titanium dioxide, zirconium oxide and aluminum oxide, preferably titanium dioxide and / or zirconium oxide.

[0035] In this invention, the Fe source has no special requirements, and can be selected from iron salt compounds.

[0036] In this invention, there are no special requirements for the inorganic salts required to form the spinel phase. Zn salts are used as an example in the embodiments, but this does not limit the scope of the invention. By employing the aforementioned preferred embodiments, the catalyst activity can be further improved.

[0037] In this invention, there are no special requirements for the high molecular weight organic compound. According to a preferred embodiment of the invention, the high molecular weight organic compound is selected from at least one of polyethylene glycol, starch, cellulose, and sucrose. Polyethylene glycol (weight-average molecular weight 40,000) is used as an example in the embodiments, but this does not limit the scope of the invention. By adopting the aforementioned preferred embodiments, the activity of the catalyst can be further improved.

[0038] In this invention, the alkali source has no special requirements. According to a preferred embodiment of the invention, the alkali source is selected from at least one of sodium carbonate, sodium hydroxide, urea, ammonia, hydrazine, and potassium hydroxide. 20 wt% ammonia is used as an example in the embodiments, but this does not limit the scope of the invention. By adopting the aforementioned preferred embodiment, the efficiency of the precipitation process can be improved, and the loss of transition metals can be avoided.

[0039] In this invention, the amount of the high molecular weight organic compound can be selected from a wide range. According to a preferred embodiment of the invention, the amount of the high molecular weight organic compound, based on the total mass of the inorganic salt, is 0.1-20 wt%, more preferably 0.5-10 wt%, and even more preferably 1-6 wt%. By adopting the aforementioned preferred embodiment, the activity of the catalyst can be further improved.

[0040] In this invention, the mass ratio of the inorganic salt and Fe source required to form the spinel phase can be selected within a wide range. According to a preferred embodiment of the invention, the mass ratio of the inorganic salt and Fe source required to form the spinel phase is 0.6-1.0, preferably 0.7-0.8. By adopting the aforementioned preferred embodiment, the catalyst activity can be further improved.

[0041] In this invention, the mass ratio of the silicon source to the Fe source can be selected within a wide range. According to a preferred embodiment of the invention, the mass ratio of the silicon source to the Fe source is 0.45-0.65. By adopting the aforementioned preferred embodiment, the catalyst activity can be further improved.

[0042] In this invention, the mass ratio of the nitrogen source to the Fe source can be selected within a wide range. According to a preferred embodiment of the invention, the mass ratio of the nitrogen source to the Fe source is 0.004-0.02. By adopting the aforementioned preferred embodiment, the catalyst activity can be further improved.

[0043] In this invention, the mass ratio of the transition metal source to the Fe source can be selected within a wide range. According to a preferred embodiment of the invention, the mass ratio of the transition metal source to the Fe source is 0.009-0.03. By adopting the aforementioned preferred embodiment, the catalyst activity can be further improved.

[0044] In this invention, the amount of alkali source is not limited, as long as it meets the pH requirements during catalyst preparation. This step is well known to those skilled in the art, and will not be described in detail here.

[0045] In this invention, there are no special requirements for the conditions of coprecipitation.

[0046] According to a preferred embodiment of the present invention, the co-precipitation temperature is 10-50°C, with 25°C being used as an example in the embodiments, but this does not limit the scope of the present invention.

[0047] According to a preferred embodiment of the present invention, the pH of the coprecipitation is 8-11, preferably 8.5-9.8.

[0048] By employing the aforementioned preferred embodiments, the catalyst activity can be further improved.

[0049] The co-precipitation time described in this invention is not limited, and those skilled in the art can choose the time according to actual operation, as long as the pH value of the co-precipitation endpoint described in this invention is reached.

[0050] By employing the aforementioned preferred embodiments, the catalyst activity can be further improved.

[0051] In this invention, there are no special requirements for the contact conditions in steps (2) and (3).

[0052] According to one embodiment of the present invention, the contact temperature in steps (2) and (3) is 0-60°C.

[0053] According to a particularly preferred embodiment of the present invention, the contact temperature of steps (2) and (3) is 80-90°C.

[0054] According to one embodiment of the present invention, the contact time in each of steps (2) and (3) is 1-300 min, with 4 h being used as an example in the embodiment, but this does not limit the scope of the present invention.

[0055] According to one embodiment of the present invention, the contact rotation speed in steps (2) and (3) is 10-1000 rpm, and 800 rpm is used as an example in the embodiment, but this does not limit the scope of the present invention.

[0056] By adopting the aforementioned preferred embodiments, the uniform distribution of the catalytically active components in the catalyst can be further improved.

[0057] In this invention, there are no special requirements for the solid content of the first slurry and the solid content of the second slurry. Those skilled in the art can choose according to actual needs, and this invention will not elaborate on this point.

[0058] In this invention, there are no special requirements for the molding method. According to a preferred embodiment of this invention, the molding method is selected from one of extrusion molding, compression molding, and spray molding.

[0059] In this invention, the molding conditions have no special requirements and are well known to those skilled in the art. They can be selected according to actual operation, and will not be described in detail here.

[0060] According to a preferred embodiment of the present invention, the calcination is carried out in an air atmosphere.

[0061] According to a preferred embodiment of the present invention, the calcination temperature is 550-750℃, preferably 620-690℃.

[0062] According to a preferred embodiment of the present invention, the roasting time is 4-12 hours, preferably 8-12 hours.

[0063] By employing the aforementioned preferred embodiments, the catalyst activity and selectivity can be further improved.

[0064] This invention provides the application of the catalyst described herein in the preparation of conjugated dienes from monoolefins, preferably in the preparation of butadiene.

[0065] This invention provides a method for the oxidative dehydrogenation of butene to butadiene suitable for low water ratio conditions. The method includes: reacting a diluent, an oxidant, butene, and a catalyst in a contact reaction; wherein the catalyst is the catalyst described in this invention.

[0066] In this invention, the diluent has no special requirements. According to a preferred embodiment of the invention, the diluent is selected from nitrogen, argon, and water vapor. In this invention, water vapor is used as an example in the embodiments, but the invention is not limited to this scope. By adopting the aforementioned preferred embodiments, the reaction performance and reactor temperature can be further improved.

[0067] In this invention, the oxidant has no special requirements. According to a preferred embodiment of the invention, the oxidant is selected from carbon dioxide, nitrogen dioxide, air, and oxygen. In this invention, oxygen is used as an example in the embodiments, but the invention is not limited to this scope. By adopting the aforementioned preferred embodiments, the catalyst performance can be further improved.

[0068] In this invention, the volume ratio of the diluent to butene is not particularly required. According to a preferred embodiment of the invention, the volume ratio of the diluent to butene is 3-8:1. The example uses a volume ratio of 5 for the diluent to butene, but this does not limit the scope of the invention. By adopting the aforementioned preferred embodiment, the operational stability of the catalyst can be further improved.

[0069] In this invention, the volume ratio of the oxidant to butene is not particularly required. According to a preferred embodiment of the invention, the volume ratio of the oxidant to butene is 0.4-1. The examples illustrate a volume ratio of 0.7, but this does not limit the scope of the invention. By employing the aforementioned preferred embodiments, the catalyst performance can be further improved.

[0070] In this invention, there are no special requirements for the conditions of the contact reaction.

[0071] According to a preferred embodiment of the present invention, the temperature of the contact reaction is 320-600°C, with 380°C being exemplarily described in the examples, but this does not limit the scope of the present invention.

[0072] According to a preferred embodiment of the present invention, the pressure of the contact reaction is 0-0.4 MPa, with 0.1 MPa being exemplarily described in the examples, but this does not limit the scope of the present invention.

[0073] According to a preferred embodiment of the present invention, the butene volume hourly space velocity (VHSV) of the contact reaction is 200-500 h⁻¹. -1 In the example, 400 hours -1 This is an illustrative example, but does not limit the scope of the invention.

[0074] By adopting the aforementioned preferred embodiments, the stability of the catalyst under low water ratio operating conditions can be further improved.

[0075] The hydroxyl parameters on the catalyst surface were determined by LiAlH4-gas chromatography. The XRD crystal phase structure composition was determined by X-ray diffraction.

[0076] In this invention, the composition of the catalyst—spinel phase, iron oxide phase, silicon oxide phase, nitride, and transition metal oxide—was determined by X-ray diffraction, and the composition of each component was calculated by XRD.

[0077] The pore volume, average pore size, and specific surface area of ​​the catalyst were obtained by BET specific surface area detection method.

[0078] Example 1

[0079] (1) Take 279.5g of ferric nitrate (Fe(NO3)3 9H2O), 215.3g of zinc nitrate (Zn(NO3)2 6H2O) and 14.8g of polyethylene glycol (weight average molecular weight 40000) in 800ml of deionized water, and then co-precipitate with 20wt% ammonia water at room temperature (25℃) (the pH of the precipitation endpoint is 9). After filtering the slurry obtained by precipitation, wash it twice with 800ml of deionized water, and then disperse it into a slurry with 200ml of deionized water. Let it stand at 25℃ for 3min before use.

[0080] (2) At 25°C, 150g of silica sol (38wt%, 95nm) was diluted with 300ml of water, and 3.8g of titanium nitride powder (TiN, 400 mesh) and 5.3g of titanium dioxide powder (anatase, 400 mesh) were added. The mixture was ground in a colloid mill for 4 hours to form a colloidal solution. Then, it was mixed with the above 200ml slurry and stirred evenly at 800rpm. The mixture was then spray-molded to obtain catalyst powder with an average particle size of 100μm. The catalyst was calcined at 680°C for 8 hours in an air atmosphere to obtain a composite oxide catalyst.

[0081] The obtained sample contained 49.5 wt% zinc ferrite spinel phase, 6.5 wt% iron oxide phase, 38 wt% silicon oxide phase, 2.5 wt% titanium nitride and 3.5 wt% titanium dioxide, with a pore volume of 2.3 ml / g, an average pore size of 22 nm, and a specific surface area of ​​26 m². 2 / g; surface hydroxyl groups 263μmol / g.

[0082] (3) At a reaction temperature of 380℃, a reaction pressure of 0.1MPa, and a butene (1-butene) volume hourly space velocity of 400 h⁻¹ -1 Under the conditions of H2O / butene volume ratio of 5 and O2 / butene volume ratio of 0.7, after 50 hours of reaction, the butene conversion rate was 72.7% and the butadiene selectivity was 92.5%; after 200 hours, the butene conversion rate was 72.2% and the butadiene selectivity was 92.0%.

[0083] Example 2

[0084] (1) Take 260.6g of ferric nitrate (Fe(NO3)3 9H2O), 187.0g of zinc nitrate (Zn(NO3)2 6H2O) and 3g of polyethylene glycol (weight average molecular weight 40000) in 800ml of deionized water, and then co-precipitate with 20wt% ammonia water at room temperature (25℃) (pH of precipitation endpoint is 9.8). After filtering the slurry obtained by precipitation, wash it twice with 800ml of deionized water, and then disperse it into a slurry with 200ml of deionized water for later use.

[0085] (2) At 40°C, 162.0g of silica sol (38wt%, 95nm) was diluted with 300ml of water, and 4.5g of chromium nitride powder (CrN, 400 mesh) and 7.5g of titanium dioxide powder (anatase, 400 mesh) were added. The mixture was ground in a colloid mill for 4 hours to form a colloidal solution. Then, it was mixed with the above 200ml slurry and stirred evenly at 800rpm. The mixture was then spray-molded to obtain catalyst powder with an average particle size of 120μm. The catalyst was calcined at 625°C for 12 hours to obtain a composite oxide catalyst.

[0086] The obtained sample contained 43.0 wt% zinc ferrite spinel phase, 8.0 wt% iron oxide phase, 41 wt% silicon oxide phase, 3.0 wt% chromium nitride, and 5.0 wt% titanium dioxide, with a pore volume of 2.4 ml / g, an average pore size of 23 nm, and a specific surface area of ​​25 m². 2 / g; surface hydroxyl groups 379μmol / g.

[0087] (3) Using the same evaluation conditions as step (3) in Example 1: after 50 hours of reaction, the butene conversion rate was 76.7% and the butadiene selectivity was 94.5%; after 200 hours, the butene conversion rate was 76.3% and the butadiene selectivity was 94.6%.

[0088] Example 3

[0089] (1) Take 301.2g of ferric nitrate (Fe(NO3)3 9H2O), 239.2g of zinc nitrate (Zn(NO3)2 6H2O) and 8.2g of polyethylene glycol (weight average molecular weight 40000) in 800ml of deionized water, and then co-precipitate with 20wt% ammonia water at room temperature (25℃) (pH of precipitation endpoint is 8.5). After filtering the slurry obtained by precipitation, wash it twice with 800ml of deionized water, and then disperse it into a slurry with 200ml of deionized water for later use.

[0090] (2) At 60°C, 142.1g of silica sol (38wt%, 95nm) was diluted with 300ml of water, and 1.5g of titanium nitride powder (TiN, 400 mesh) and 3.0g of zirconium dioxide powder (400 mesh) were added. The mixture was ground in a colloid mill for 4 hours to form a colloidal solution. Then, it was mixed with the above 200ml slurry and stirred evenly at 800rpm. The mixture was then spray-molded to obtain catalyst powder with an average particle size of 80μm. The catalyst was calcined at 650°C for 10 hours in an air atmosphere to obtain a composite oxide catalyst.

[0091] The obtained sample contained 55.0 wt% zinc ferrite spinel phase, 6.0 wt% iron oxide phase, 36 wt% silicon oxide phase, 1.0 wt% titanium nitride and 2.0 wt% titanium dioxide, with a pore volume of 2.3 ml / g, an average pore size of 22 nm, and a specific surface area of ​​24 m². 2 / g; surface hydroxyl groups 103μmol / g.

[0092] (3) Using the same evaluation conditions as step (3) in Example 1: after 50 hours of reaction, the butene conversion rate was 70.9% and the butadiene selectivity was 92.3%; after 200 hours, the butene conversion rate was 70.1% and the butadiene selectivity was 91.6%.

[0093] Example 4

[0094] All conditions were the same as in Example 1, except that the calcination temperature in step (2) was 780°C to obtain the composite oxide catalyst.

[0095] Pore ​​volume 2.0 ml / g, average pore size 20 nm, specific surface area 21 m² 2 / g; surface hydroxyl groups 62μmol / g.

[0096] (3) Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 72.1% and the butadiene selectivity was 91.9%; after 200 hours, the butene conversion rate was 64.3% and the butadiene selectivity was 89.1%.

[0097] Example 5

[0098] All conditions are the same as in Example 1, except that:

[0099] In step (1), 257.8g of ferric nitrate (Fe(NO3)3 9H2O), 176.6g of zinc nitrate (Zn(NO3)2 6H2O) and 13.0g of polyethylene glycol (weight average molecular weight 40000) were placed in 800ml of deionized water and then co-precipitated.

[0100] In step (2), 155.5g of silica sol (38wt%, 95nm) was diluted with 300ml of water, and 6.9g of titanium nitride powder (TiN, 400 mesh) and 9.5g of titanium dioxide powder (anatase, 400 mesh) were added. After grinding in a colloid mill for 4 hours, a colloidal solution was formed. Then, it was mixed with the above 200ml slurry, stirred evenly, and spray-formed to obtain catalyst powder with a certain particle size distribution. After calcination at 680℃ for 8 hours, a composite oxide catalyst was obtained.

[0101] The obtained sample contained 40.6 wt% zinc ferrite spinel phase, 9.1 wt% iron oxide phase, 39.4 wt% silicon oxide phase, 4.6 wt% titanium nitride and 6.3 wt% titanium dioxide, with a pore volume of 2.6 ml / g, an average pore size of 27 nm, and a specific surface area of ​​28 m². 2 / g; surface hydroxyl groups 486μmol / g.

[0102] (3) Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 71.8% and the butadiene selectivity was 91.5%; after 200 hours, the butene conversion rate was 65.2% and the butadiene selectivity was 88.2%.

[0103] Example 6

[0104] All conditions are the same as in Example 1, except that in step (1), 257.8g of ferric nitrate (Fe(NO3)39H2O), 174.7g of copper nitrate (Cu(NO3)2.3H2O) and 13.6g of polyethylene glycol (weight average molecular weight 40000) are placed in 800ml of deionized water and then co-precipitated.

[0105] In step (2), at 25°C, 150.1g of silica sol (38wt%, 95nm) was diluted with 300ml of water, and 3.8g of boron nitride powder (BN, average particle size 400 mesh) and 5.3g of alumina powder (average particle size 400 mesh) were added. After grinding in a colloid mill for 4 hours, a colloidal solution was formed. Then, it was mixed with the above 200ml slurry, stirred evenly, and spray-formed to obtain catalyst powder with a certain particle size distribution. After calcination at 680°C for 8 hours, a composite oxide catalyst was obtained.

[0106] The obtained sample contained 49.5 wt% copper ferrite spinel phase, 6.5 wt% iron oxide phase, 38 wt% silicon oxide phase, 2.5 wt% boron nitride and 3.5 wt% aluminum oxide phase, with a pore volume of 2.5 ml / g, an average pore size of 25 nm and a specific surface area of ​​26 m². 2 / g; surface hydroxyl groups 405μmol / g.

[0107] Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 73.3% and the butadiene selectivity was 92.1%; after 200 hours, the butene conversion rate was 68.2% and the butadiene selectivity was 90.3%.

[0108] Example 7

[0109] The catalyst was obtained by following the method of Example 3, except that the contact temperature in step (2) was 80°C and the other conditions were different;

[0110] After 50 hours of reaction, the butene conversion rate was 71.9% and the butadiene selectivity was 93.6%; after 200 hours, the butene conversion rate was 71.1% and the butadiene selectivity was 92.8%.

[0111] Comparative Example 1

[0112] The catalyst was prepared according to the method of Example 1, except that silicon dioxide, titanium nitride and titanium dioxide were not added, and step (2) was not performed.

[0113] Pore ​​volume 1.9 ml / g, average pore size 19 nm, specific surface area 16 m² 2 / g; surface hydroxyl groups 19μmol / g.

[0114] Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 7.3% and the butadiene selectivity was 90.3%; after 200 hours, the butene conversion rate was 61.1% and the butadiene selectivity was 86.0%.

[0115] Comparative Example 2

[0116] The catalyst was prepared according to the method of Example 1, except that titanium nitride and titanium dioxide were not added, and titanium nitride and titanium dioxide were not added in step (2).

[0117] Pore ​​volume 2.4 ml / g, average pore size 21 nm, specific surface area 22 m² 2 / g; surface hydroxyl groups 98μmol / g.

[0118] Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 68.5% and the butadiene selectivity was 90.6%; after 200 hours, the butene conversion rate was 61.2% and the butadiene selectivity was 88.2%.

[0119] Comparative Example 3

[0120] The catalyst was prepared according to the method of Example 1, except that silica sol was not added in step (2).

[0121] Pore ​​volume 1.8 ml / g, average pore size 16 nm, specific surface area 19 m² 2 / g; surface hydroxyl groups 163μmol / g.

[0122] Using the same evaluation conditions as step (3) in the same example: after 50 hours of reaction, the butene conversion rate was 69.9% and the butadiene selectivity was 91.0%; after 200 hours, the butene conversion rate was 62.8% and the butadiene selectivity was 89.1%.

[0123] 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 method for the oxidative dehydrogenation of butene to butadiene suitable for low water ratio conditions, characterized in that, The method includes: Water vapor, oxidant, butene, and catalyst are reacted in contact; the volume ratio of water vapor to butene is 3-5:

1. The catalyst comprises: spinel phase, iron oxide phase, silicon oxide phase, nitride and transition metal oxide; wherein the surface hydroxyl content of the catalyst is 60-500 μmol / g; The preparation method of this catalyst includes: (1) The Fe source, inorganic salts and high molecular weight organic matter required to form the spinel phase are co-precipitated with the alkali source, the solid and liquid are separated, and after washing, they are dispersed in a solvent to form the first slurry; (2) The nitrogen source, transition metal source and silicon source are contacted in a solvent and ground into a colloidal solution to form a second slurry; (3) The second slurry is brought into contact with the first slurry, shaped, and fired; The mass ratio of the nitrogen source to the Fe source is 0.004-0.02; The mass ratio of the transition metal source to the Fe source is 0.009-0.

03.

2. The method according to claim 1, wherein, Based on 100wt% of catalyst, The content of spinel phase is 40-60 wt%; and / or The content of iron oxide crystalline phase is 5-10 wt%; and / or The content of the silica crystalline phase is 30-50 wt%; and / or The nitride content is 0.5-5 wt%; and / or The content of transition metal oxides is 0.1-8 wt%; and / or The nitride is selected from at least one of boron nitride, zirconium nitride, chromium nitride, magnesium nitride, iron nitride, and titanium nitride; and / or The transition metal oxide is selected from at least one of titanium dioxide, zirconium oxide, and aluminum oxide.

3. The method according to claim 2, wherein, Based on 100wt% of catalyst, The content of spinel phase is 43-55 wt%; and / or The content of iron oxide crystalline phase is 6-8 wt%; and / or The content of silicon dioxide crystalline phase is 35-45 wt%; and / or The content of nitrides is 1-3 wt%; and / or The content of transition metal oxides is 2-5 wt%; and / or The nitride is selected from at least one of zirconium nitride, chromium nitride, and titanium nitride; and / or The transition metal oxide is titanium dioxide and / or zirconium oxide.

4. The method according to claim 1, wherein, The catalyst has a surface hydroxyl content of 100-400 μmol / g; and / or The catalyst has a pore volume of 0.2-6 mL / g; and / or The catalyst has an average pore size of 1-90 nm; and / or The catalyst has a specific surface area of ​​1-80 m². 2 / g; and / or The average particle size of the catalyst is 20-160 μm; and / or The spinel phase structure satisfies the chemical formula: AFe2O4, wherein A is selected from at least one of Ca, Mn, Co, Ni, Zn, Cd, Hg, Mg and Sn.

5. The method according to claim 4, wherein, The catalyst has a pore volume of 2-2.5 mL / g; and / or The catalyst has an average pore size of 20-25 nm; and / or The catalyst has a specific surface area of ​​22-28 m². 2 / g; and / or The average particle size of the catalyst is 80-120 μm.

6. The method according to claim 1, wherein, The high molecular weight organic compound is selected from at least one of polyethylene glycol, starch, cellulose and sucrose; and / or The alkali source is selected from at least one of sodium carbonate, sodium hydroxide, urea, ammonia, hydrazine, and potassium hydroxide; and / or The silicon source is silica sol.

7. The method according to claim 6, wherein, The silica sol has an average particle size of 20-200 nm and a solid content of 30-38 wt%.

8. The method according to claim 7, wherein, The average particle size of the silica sol is 80-160 nm.

9. The method according to claim 1, wherein, The nitrogen source is at least one of boron nitride, zirconium nitride, chromium nitride, magnesium nitride, iron nitride, and titanium nitride; and / or The transition metal source is at least one of titanium dioxide, zirconium oxide, and aluminum oxide; and / or The Fe source is selected from iron salt compounds; and / or Based on the total mass of the inorganic salts, The amount of the high molecular weight organic compound used is 0.1-20 wt%; and / or The mass ratio of the inorganic salt and Fe source required to form the spinel phase is 0.6-1.0; and / or The mass ratio of the silicon source to the Fe source is 0.45-0.

65.

10. The method according to claim 9, wherein, The nitrogen source is at least one of zirconium nitride, chromium nitride, and titanium nitride; and / or The transition metal source is titanium dioxide and / or zirconium oxide; and / or Based on the total mass of the inorganic salts, The amount of the high molecular weight organic compound used is 0.5-10 wt%; and / or The mass ratio of the inorganic salt and Fe source required to form the spinel phase is 0.7-0.

8.

11. The method according to claim 10, wherein, The amount of the high molecular weight organic compound is 1-6 wt% based on the total mass of the inorganic salts.

12. The method according to claim 1, wherein, The conditions for coprecipitation include: a temperature of 10-50°C; and / or a pH of 8-11; and / or The contact temperatures in steps (2) and (3) are each 80-90℃; and / or The molding method is selected from one of extrusion molding, compression molding, and spray molding; and / or The calcination is carried out in an air atmosphere, and the calcination conditions include: Temperature is 550-750℃; and / or time is 4-12 hours.

13. The method according to claim 12, wherein, The conditions for the coprecipitation include: pH 8.5-9.8; and / or The calcination conditions include: a temperature of 620-690℃; and / or a time of 8-12h.

14. The method according to claim 1, wherein, The oxidant is selected from nitrogen dioxide, carbon dioxide, air, and oxygen; and / or The volume ratio of oxidant to butene is 0.4-1; and / or The conditions for the contact reaction include: Temperature 320-600℃; and / or pressure 0-0.4MPa; and / or butene volume hourly space velocity 200-500 h⁻¹ -1 .