Isobutane dehydrogenation catalyst, method for preparing the same, and use thereof

Abstract

This invention relates to the field of catalytic dehydrogenation, and discloses an isobutane dehydrogenation catalyst, its preparation method, and its application. The catalyst comprises a support and an active metal component supported on the support. The support comprises a composite metal oxide and silicon dioxide; wherein the composite metal oxide is M... 2+ 1‑x M 3+ x O (x+2) / 2 x is 0.1-0.4, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following. The catalyst described in this invention exhibits high catalytic activity and selectivity in the dehydrogenation of isobutane to isobutene. Moreover, the catalyst described in this invention is easy to recover and can be reused, and is less prone to coking than traditional alumina supports. Furthermore, the raw materials are readily available, the cost is low, and the preparation is simple, making it suitable for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of catalyst dehydrogenation, specifically to an isobutane dehydrogenation catalyst, its preparation method, and its application in the dehydrogenation of isobutane to prepare isobutene. Background Technology

[0002] Methyl tert-butyl ether and ethyl tert-butyl ether are high-performance gasoline additives due to their high octane number, low vapor pressure, and good solubility in gasoline. The demand for isobutylene, the raw material for their preparation, has also increased significantly. However, the yield of isobutylene prepared by traditional catalytic cracking and thermal processing is difficult to meet the needs of industrial production. Therefore, it is necessary to improve the process of isobutylene preparation by isobutane dehydrogenation to meet or at least alleviate the shortage of isobutylene.

[0003] The dehydrogenation of isobutane to isobutene is generally carried out in the presence of an isobutane dehydrogenation catalyst. Existing catalyst systems mainly include oxide catalysts and noble metal catalysts, with alumina being the most commonly used support. For example, CN1185994A discloses a catalyst for the catalytic dehydrogenation of isobutane to isobutene, prepared by co-precipitation and slurry mixing methods, with the catalyst formula A. a B b C c D d O x The expression for a supported catalyst prepared by impregnation method: A a B b C c / Support, (1)A is an element selected from Cr, Pt, V, (2)B is one or two elements selected from La, Dy, Cu, Be, Ag, Mg, Ca, Ba, Zr, Sn, Fe, (3)C is an element selected from Li, Na, K, (4)D is an element selected from Al, Si, Ti, Zr, (5)The support for the catalyst can be silica spheres, aluminum spheres, silica-alumina spheres, titanium-alumina spheres, or molecular sieves, wherein the atomic ratios of a / d, a / b, and a / c vary in the range of 0.001-30, and the loading of the effective component in the catalyst is 0.01-50% (by weight). However, during the catalytic reaction, the weak acidity of the support makes the catalyst prone to coking at high temperatures, resulting in a very short regeneration cycle, which makes the development of new catalyst supports necessary. Summary of the Invention

[0004] The purpose of this invention is to provide a novel isobutane dehydrogenation catalyst and its preparation method, as well as the application of the isobutane dehydrogenation catalyst in the dehydrogenation of isobutane to prepare isobutene. This catalyst has a longer regeneration cycle and exhibits higher catalytic activity and selectivity.

[0005] To achieve the above objectives, a first aspect of the present invention provides an isobutane dehydrogenation catalyst, the catalyst comprising a support and an active metal component supported on the support.

[0006] The carrier comprises a composite metal oxide and silicon dioxide;

[0007] Wherein, the composite metal oxide is M 2+ 1-x M 3+ x O (x+2) / 2 x is 0.1-0.4, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of them.

[0008] Preferably, the active metal component is Pd.

[0009] Preferably, the content of the active metal component is 0.1-5 wt% based on the total weight of the catalyst, calculated by metal element.

[0010] Preferably, in the carrier, the content of silicon dioxide is 1-10 parts by weight, more preferably 3-6 parts by weight, compared to 100 parts by weight of dihydroxy composite metal oxide.

[0011] A second aspect of the present invention provides a method for preparing an isobutane dehydrogenation catalyst, the method comprising:

[0012] (1) A carrier is obtained by mixing a dihydroxy composite metal oxide with the structure shown in formula (1) with silicon dioxide, and then molding, drying and calcining it.

[0013] (2) The active metal component is loaded onto the support obtained in step (1), and after drying and calcination, an isobutane dehydrogenation catalyst is obtained.

[0014] [M 2+ 1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O (1)

[0015] Among them, M 2+ Selected from Mg 2+ Ni 2+ and Zn2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following; x is 0.1-0.4, preferably 0.2-0.35; and m is any number from 2 to 12.

[0016] The third aspect of the present invention provides an isobutane dehydrogenation catalyst prepared by the preparation method described above.

[0017] The fourth aspect of the present invention provides the application of the isobutane dehydrogenation catalyst described above in the dehydrogenation of isobutane to prepare isobutene.

[0018] When the isobutane dehydrogenation catalyst prepared in this invention is evaluated in a fixed-bed dehydrogenation microreactor for the catalytic dehydrogenation of isobutane to produce isobutene, the conversion rate of isobutane can reach 50-70%, and the selectivity of isobutene can reach 90-99%. That is, the catalyst described in this invention has high catalytic activity and selectivity in the dehydrogenation of isobutane to produce isobutene.

[0019] Moreover, the catalyst described in this invention is easy to recover and can be reused, and is less prone to coking than traditional alumina supports. Furthermore, the raw materials are readily available, the cost is low, and the preparation is simple, making it suitable for industrial applications. Detailed Implementation

[0020] 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.

[0021] The first aspect of this invention provides an isobutane dehydrogenation catalyst, the catalyst comprising a support and an active metal component supported on the support.

[0022] The carrier comprises a composite metal oxide and silicon dioxide;

[0023] Wherein, the composite metal oxide is M 2+ 1-x M 3+ x O (x+2) / 2 x is 0.1-0.4, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of them.

[0024] Preferably, the active metal component is Pd.

[0025] Preferably, the content of the active metal component, based on the total weight of the catalyst and calculated by metal elements, is 0.1-5 wt%, more preferably 0.5-3 wt%, for example, it can be 0.5, 1, 1.5, 2, 2.5, 3 wt%, or any range between any two values.

[0026] The composite metal oxide is M 2+ 1-x M 3+ x O (x+2) / 2 Preferably, x is between 0.2 and 0.35, for example, it can be 0.2, 0.25, 0.3, 0.35, or any range between any two values. It should be understood that x is M. 3+ / (M 2+ +M 3+ The molar ratio of ).

[0027] M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of them.

[0028] The preparation method of the carrier can be a conventional preparation method in the art. In a preferred embodiment of the present invention, the preparation method of the carrier includes mixing a dihydroxy composite metal oxide having the structure shown in formula (1) and silicon dioxide, followed by molding, drying and calcination to obtain the carrier.

[0029] [M 2+ 1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O (1)

[0030] Among them, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+At least one of the following: x is 0.1-0.4 (e.g., it can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range between any two values), preferably 0.2-0.35; and m is any number from 2 to 12 (e.g., it can be 2, 4, 6, 8, 10, 12, or any range between any two values).

[0031] For details on how to do this method, please refer to the second part, which will not be repeated here.

[0032] Preferably, in the carrier, the content of silicon dioxide is 1-10 parts by weight compared to 100 parts by weight of the dihydroxy composite metal oxide, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight and any range between any two values, preferably 3-6 parts by weight.

[0033] In a preferred embodiment of the present invention, the catalyst comprises a support and an active metal component supported on the support, wherein the support comprises a composite metal oxide and silicon dioxide; wherein the composite metal oxide is M 2+ 1-x M 3 + x O (x+2) / 2 x is 0.1-0.4, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following, based on the total weight of the catalyst, the content of the active metal component is 0.5-3 wt% by metal element, the content of the composite metal oxide is 87-97 wt% by oxide, and the content of silicon dioxide is 2-9 wt% by oxide.

[0034] A second aspect of the present invention provides a method for preparing an isobutane dehydrogenation catalyst, the method comprising:

[0035] (1) A carrier is obtained by mixing a dihydroxy composite metal oxide with the structure shown in formula (1) with silicon dioxide, and then molding, drying and calcining it.

[0036] (2) The active metal component is loaded onto the support obtained in step (1), and after drying and calcination, an isobutane dehydrogenation catalyst is obtained.

[0037] [M 2+1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O (1)

[0038] Among them, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following; x is 0.1-0.4, preferably 0.2-0.35; and m is any number from 2 to 12.

[0039] The dihydroxy composite metal oxides with the structure shown in formula (1) used in this invention can be commercially available products or prepared according to existing technologies, the preparation techniques of which are known to those skilled in the art, such as co-precipitation, nucleation / isolation, non-equilibrium crystallization, or hydrothermal synthesis. The resulting products are typically nano- or submicron-sized layered dihydroxy composite metal oxide particles.

[0040] In a preferred embodiment of the present invention, a dihydroxy composite metal oxide having the structure shown in formula (1) is prepared by a method comprising the following steps:

[0041] Al 3+ Water-soluble salts and M 2+ Water-soluble salts are mixed in the presence of an alkaline precipitant (such as NaOH and / or sodium carbonate) or urea to obtain a mixed slurry. The mixed slurry is added to a crystallization vessel and stirred for crystallization to obtain a crystallized product. The crystallized product is then thoroughly washed with deionized water to make the pH of the supernatant 7-8, and then dried at a temperature of 50-160℃ to obtain a dried product with the structure shown in formula (1). For details, please refer to CN102211972A.

[0042] As a trivalent metal ion M 3+ Water-soluble salts, including M 3+ Nitrates, sulfates, chlorides, and basic carbonates are preferred, with nitrates being the most suitable.

[0043] As a divalent metal ion M 2+ Water-soluble salts, including M 2+ Nitrates, sulfates, chlorides, and basic carbonates are preferred, with nitrates being the most suitable.

[0044] As an alkaline precipitant, any substance capable of precipitating trivalent metal ions M can be used. 3+ Water-soluble salts and divalent metal ions M 2 + An alkaline reagent for precipitating water-soluble salts is preferred; preferably, a combination of alkali and carbonate is used. The alkali can be, for example, sodium hydroxide, potassium hydroxide, ammonia, etc., and the carbonate can be, for example, sodium carbonate, potassium carbonate, etc. Urea can also be used instead of alkali and carbonate. The amount of alkaline precipitant or urea can be selected within a wide range, as long as it allows M to... 3+ Water-soluble salts and M 2+ Water-soluble salts can be precipitated.

[0045] The silicon dioxide described in this invention can be silicon dioxide conventionally used in the art, or it can be a commercially available product.

[0046] Preferably, compared to 100 parts by weight of the dihydroxy composite metal oxide, the content of silicon dioxide is 1-10 parts by weight, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight and any range between any two values, more preferably 3-6 parts by weight.

[0047] In step (1), the molding, drying and calcining methods can be any method in the art, and those skilled in the art can choose as needed, which will not be elaborated here.

[0048] In this invention, a binder is preferably used during the molding process. The binder can be a conventional binder in the art, such as an acid solution. Preferably, the binder is nitric acid.

[0049] The adhesive solvent can be provided in solution form, and its concentration can be selected within a wide range. Preferably, the concentration of the adhesive solvent solution is 1-5 wt%.

[0050] The amount of the adhesive solvent can be selected within a wide range. Preferably, the amount of the adhesive solvent solution is 10-30 parts by weight, compared to 100 parts by weight of the mixture of dihydroxy composite metal oxide and silicon dioxide.

[0051] Preferably, in step (1), the drying conditions include: a temperature of 100-160°C and a time of 2-24 hours.

[0052] Preferably, in step (1), the calcination conditions include: a temperature of 400-600℃ and a time of 2-24h.

[0053] The method of loading the active metal component onto the support obtained in step (1) can be a conventional method in the art. For example, the active metal component can be loaded onto the support by impregnation to obtain an isobutane dehydrogenation catalyst, which is conventional to those skilled in the art. For example, the loading method described in CN1911242A can be used, which is incorporated herein by reference.

[0054] Preferably, the active metal component is Pd.

[0055] Preferably, the amount of the active metal component, based on the total weight of the catalyst, is 0.1-5 wt%, more preferably 0.5-3 wt%, for example, it can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 wt%, or any range between any two values.

[0056] The active metal component can be loaded onto the carrier in the form of an aqueous solution of its inorganic salt by an impregnation method. Preferably, the inorganic salt of the active metal component is palladium chloride or dichlorotetraamminepalladium.

[0057] Preferably, the content of the inorganic salt of the active metal component in the aqueous solution is 0.05-0.5 mol / L, more preferably 0.1-0.4 mol / L.

[0058] Preferably, the soaking time is 6-24 hours.

[0059] Preferably, in step (2), the drying conditions include: a temperature of 100-160℃ and a time of 2-24h.

[0060] The third aspect of the present invention provides an isobutane dehydrogenation catalyst prepared by the preparation method described above.

[0061] The fourth aspect of the present invention provides the application of the isobutane dehydrogenation catalyst described above in the dehydrogenation of isobutane to prepare isobutene.

[0062] A method for preparing isobutene by dehydrogenation of isobutane may include contacting and reacting isobutane with an isobutane dehydrogenation catalyst as described above.

[0063] The reaction conditions can be: a temperature of 400-600℃ and an isobutane space velocity of 100-600 h⁻¹. -1 .

[0064] The reaction can be carried out under normal pressure.

[0065] The reaction can be carried out in a fixed-bed reactor.

[0066] The present invention will be described in detail below through embodiments.

[0067] The microreactor used in the following examples is a tubular fixed-bed reactor with an inner diameter of 9 mm and a capacity of 25 ml. All pipelines in the device are made of stainless steel. The catalyst is loaded into the reaction isothermal zone in the form of a fixed bed, and both ends are filled with quartz sand.

[0068] The silica was purchased from Beijing Innocare Technology Co., Ltd.

[0069] Preparation Example 1

[0070] This preparation example illustrates a method for preparing compounds having the structure shown in formula (1).

[0071] [M 2+ 1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O (1)

[0072] Weigh 61.51g of Mg(NO3)2·6H2O and 45.03g of Al(NO3)3·9H2O and dissolve them in deionized water to prepare a 300mL mixed salt solution; then weigh 23.03g of NaOH and 25.43g of Na2CO3 and dissolve them in deionized water to prepare a 300mL mixed alkali solution. Add both mixed solutions simultaneously to a fully recirculating mixed liquid membrane reactor. Adjust the slit width between the reactor rotor and stator to 0.02mm, the operating voltage to 100V, and the rotor speed to 4500rpm. Mix for 2-3 minutes to obtain a mixed slurry. Add the obtained mixed slurry to a crystallization vessel and stir. Maintain the temperature of the mixed slurry in the vessel at 100℃ and reflux for 6 hours to obtain a crystallized product. Wash the crystallized product thoroughly with deionized water to adjust the pH of the supernatant to 7-8, and then dry it at 120℃ for 12 hours to obtain Mg4Al2(OH). 12 The compound shown in CO3·6H2O is denoted as A1.

[0073] Preparation Example 2

[0074] The procedure was carried out according to the method described in Preparation Example 1, except that an equimolar amount of Zn(NO3)2·6H2O was used instead of Mg(NO3)2·6H2O to obtain Zn4Al2(OH). 12 The compound shown in CO3·6H2O is denoted as A2.

[0075] Preparation Example 3

[0076] The procedure was carried out according to the method described in Preparation Example 1, except that an equimolar amount of Ni(NO3)2·6H2O was used instead of Mg(NO3)2·6H2O to obtain Ni4Al2(OH). 12 The compound shown in CO3·6H2O is denoted as A3.

[0077] Preparation Example 4

[0078] The procedure was performed according to the method described in Preparation Example 1, except that the amounts of each component were adjusted to prepare Mg6Al2(OH). 16 The compound shown in CO3·6H2O is denoted as A4.

[0079] Preparation Example 5

[0080] The procedure was performed according to the method described in Preparation Example 1, except that the amounts of each component were adjusted to prepare Mg8Al2(OH). 20 The compound shown in CO3·6H2O is denoted as A5.

[0081] Preparation Example 6

[0082] The procedure was performed according to the method described in Preparation Example 1, except that an equimolar amount of Fe(NO3)3·9H2O was used instead of Al(NO3)3·9H2O to obtain Mg4Fe2(OH). 12 The compound shown in CO3·6H2O is denoted as A6.

[0083] Example 1

[0084] This embodiment illustrates the preparation method of the isobutane dehydrogenation catalyst described in this invention.

[0085] The compounds with the structure shown in formula (1) prepared in Examples 1-6 were mixed with silica, and 2 wt% nitric acid solution was added, with the amount added being 20 wt% of the solid mixture. The mixture was kneaded, extruded into strips, dried at 120 °C, and calcined at 500 °C for 4 h to obtain a support. The support was impregnated in 0.2 mol / L palladium chloride solution for 8 h, washed, dried at 120 °C, and calcined at 500 °C for 12 h to obtain isobutane dehydrogenation catalysts Y1-Y13, respectively.

[0086] The types of compounds of formula (1) in catalysts Y1-Y13, the weight of SiO2 relative to 100g of compound (1), and the content of Pd in ​​the catalysts are shown in Table 1.

[0087] Comparative Example 1

[0088] This comparative example is used to illustrate the preparation method of the reference isobutane dehydrogenation catalyst.

[0089] The procedure was carried out according to the method described in Preparation Example 1, except that an equal weight of Fe2O3 was used instead of SiO2. The composition of the catalyst is shown in Table 1, and the results of the isobutane conversion and isobutene selectivity of the obtained catalyst are shown in Table 1.

[0090] Comparative Example 2

[0091] This comparative example is used to illustrate the preparation method of the reference isobutane dehydrogenation catalyst.

[0092] The procedure was carried out according to the method described in Preparation Example 1, except that SiO2 was not used. The composition of the catalyst is shown in Table 1, and the results of the isobutane conversion and isobutene selectivity of the obtained catalyst are shown in Table 1.

[0093] Test Example 1

[0094] 2g of the prepared catalyst was loaded into each microreactor, and the reaction temperature was controlled at 500℃ and the isobutane space velocity at 200h⁻¹. -1 The reaction produces isobutylene.

[0095] The isobutane conversion and isobutene selectivity of the obtained catalyst were determined, and the results are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] 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. An isobutane dehydrogenation catalyst, characterized in that, The catalyst comprises a support and an active metal component supported on the support. The carrier comprises a composite metal oxide and silicon dioxide; Wherein, the composite metal oxide is M 2+ 1-x M 3+ x O (x+2) / 2 x is 0.1-0.4, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of them; Based on the total weight of the catalyst, the content of the active metal component, calculated by metal element, is 0.1-5 wt%. The method for preparing the carrier includes mixing a dihydroxy composite metal oxide having the structure shown in formula (1) with silicon dioxide, followed by molding, drying, and calcination. [M 2+ 1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 · mH2O(1) Among them, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following; x is between 0.1 and 0.4; and m is any number between 2 and 12; In the carrier, the content of silicon dioxide is 1-10 parts by weight compared to 100 parts by weight of dihydroxy composite metal oxide.

2. The catalyst according to claim 1, wherein, The active metal component is Pd; and / or Based on the total weight of the catalyst, the content of the active metal component, calculated by metal element, is 0.5-3 wt%.

3. The catalyst according to claim 1 or 2, wherein, x is between 0.2 and 0.

35.

4. The catalyst according to claim 1, wherein, In the carrier, the content of silicon dioxide is 3-6 parts by weight compared to 100 parts by weight of dihydroxy composite metal oxide.

5. A method for preparing an isobutane dehydrogenation catalyst, characterized in that, The method includes: (1) A carrier is obtained by mixing a dihydroxy composite metal oxide with the structure shown in formula (1) with silicon dioxide, and then molding, drying and calcining it. (2) The active metal component is loaded onto the support obtained in step (1), and after drying and calcination, an isobutane dehydrogenation catalyst is obtained; [M 2+ 1-x M 3+ x (OH)2] x+ ·(CO3 2- ) x / 2 · mH2O(1) Among them, M 2+ Selected from Mg 2+ Ni 2+ and Zn 2+ At least one of them; M 3+ Selected from Al 3+ Cr 3+ Co 3+ and Fe 3+ At least one of the following; x is between 0.1 and 0.4; and m is any number between 2 and 12; The amount of the active metal component, calculated by metal element, is such that, based on the total weight of the catalyst, the content of the active metal component is 0.1-5 wt%. The amount of silicon dioxide used is 1-10 parts by weight, compared to 100 parts by weight of dihydroxy composite metal oxide.

6. The preparation method according to claim 5, wherein, x is between 0.2 and 0.35; And / or, based on the amount of metal element, the active metal component is used such that, based on the total weight of the catalyst, the content of the active metal component is 0.5-3 wt%; And / or, the active metal component is Pd.

7. The preparation method according to claim 5 or 6, wherein, Compared to 100 parts by weight of dihydroxy composite metal oxide, the amount of silicon dioxide used is 3-6 parts by weight.

8. The preparation method according to claim 5, wherein, In step (1), a glue solvent is used for molding during the molding process, and the glue solvent is nitric acid; The drying conditions include: a temperature of 100-160℃ and a time of 2-24 hours; and / or The roasting conditions include a temperature of 400-600℃ and a time of 2-24h.

9. The preparation method according to claim 5, wherein, In step (2), the drying conditions include: a temperature of 100-160℃ and a time of 2-24h.

10. The isobutane dehydrogenation catalyst prepared by the preparation method according to any one of claims 5-9.

11. The use of the isobutane dehydrogenation catalyst according to any one of claims 1-4 and 10 in the dehydrogenation of isobutane to prepare isobutene.

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