Isobutane dehydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of catalyst dehydrogenation, and discloses an isobutane dehydrogenation catalyst and a preparation method and application thereof.The isobutane dehydrogenation catalyst comprises a carrier and an active metal component loaded on the carrier, and the active metal component is vanadium; wherein in terms of metal elements, the content of the active metal component is 0.1-5wt% on the basis of the total weight of the catalyst; the carrier comprises a composite metal oxide and silicon dioxide; wherein the composite metal oxide is M < 1-x > Al < x > O (x + 2) / 2, x is 0.1-0.4, and M is selected from at least one of Mg, Ni and Zn. The catalyst provided by the invention is used in a reaction for preparing isobutene by dehydrogenation of isobutane, and has relatively high catalytic activity and selectivity. Moreover, the catalyst provided by the invention is easy to recover and can be repeatedly used, and compared with the traditional alumina carrier, the catalyst is not easy to coke, and the raw materials are easy to obtain, the cost is low, the preparation is simple, and the catalyst is suitable for industrial application.

Description

Technical Field

[0001] The present invention relates to the field of catalyst dehydrogenation, and in particular to an isobutane dehydrogenation catalyst and a preparation method thereof, and application of the isobutane dehydrogenation catalyst in the preparation of isobutene by dehydrogenating isobutane. Background Art

[0002] As a raw material for preparing methyl tert-butyl ether and ethyl tert-butyl ether, the output of butene produced in traditional catalytic cracking and thermal processing processes is difficult to meet the needs of industrial production. It is necessary to improve the process of producing isobutylene by dehydrogenation of isobutane to alleviate the shortage of isobutylene. Since the dehydrogenation of isobutane to produce isobutylene is generally carried out in the presence of an isobutane dehydrogenation catalyst, it is possible to start with the isobutane dehydrogenation catalyst and further increase the isobutylene output by improving the isobutane dehydrogenation catalyst.

[0003] CN1185994A discloses a catalyst for catalytic dehydrogenation of isobutane to prepare isobutene. The catalyst is prepared by coprecipitation and slurry mixing method and is represented by A a B b C c D d O x , the expression of the supported catalyst prepared by impregnation method: A a B b C c / carrier, (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 carrier of the supported catalyst can be silicon spheres, aluminum spheres, silicon aluminum spheres and titanium aluminum 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 amount of the effective component in the supported catalyst is 0.01-50% (by weight). However, during the catalytic reaction, the weak acidity of the carrier makes the catalyst prone to coking at high temperatures, and the regeneration cycle is very short, which affects the continuous production of isobutylene, so it is necessary to develop a new catalyst. Summary of the invention

[0004] The purpose of the present invention is to provide a new isobutane dehydrogenation catalyst and a preparation method thereof, and use of the isobutane dehydrogenation catalyst in the dehydrogenation of isobutane to prepare isobutylene. The catalyst can have a longer regeneration cycle and has higher catalytic activity and selectivity.

[0005] In order to achieve the above object, the present invention provides an isobutane dehydrogenation catalyst in a first aspect, the catalyst comprising a carrier and an active metal component supported on the carrier.

[0006] Wherein, the active metal component is vanadium;

[0007] Wherein, the content of active metal component is 0.1-5wt% based on the total weight of the catalyst in terms of metal element;

[0008] The carrier comprises a composite metal oxide and silicon dioxide;

[0009] Wherein, the composite metal oxide is M 1-x Al x O (x+2) / 2 , x is M 2+ / (M 2+ +Al 3+ ), x is 0.1-0.4, and M is selected from at least one of Mg, Ni and Zn.

[0010] Preferably, calculated as oxide, based on the weight of the composite metal oxide, the content of silicon dioxide is 1-10 wt%.

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

[0012] (1) In the presence of an acid solution, a compound having a structure represented by formula (1) is mixed with silicon dioxide, and the mixture is molded, dried, and calcined to obtain a carrier;

[0013] (2) loading the active metal component onto the carrier obtained in step (1), and obtaining an isobutane dehydrogenation catalyst after drying and calcining;

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

[0015] wherein M is selected from at least one of Mg, Ni and Zn; x is 0.1-0.4, preferably 0.2-0.33; and m is any number from 2 to 9;

[0016] Wherein, the active metal component is vanadium;

[0017] Wherein, the amount of the active metal component is such that, based on the total weight of the catalyst, the content of the active metal component is 0.1-5 wt %.

[0018] The third aspect of the present invention provides an isobutane dehydrogenation catalyst prepared by the preparation method described above.

[0019] A fourth aspect of the present invention provides use of the isobutane dehydrogenation catalyst as described above in the dehydrogenation of isobutane to prepare isobutene.

[0020] When the isobutane dehydrogenation catalyst prepared by the present invention is evaluated for the reaction of catalytic dehydrogenation of isobutane to generate isobutene through a fixed bed dehydrogenation micro-reactor, the conversion rate of the reactant isobutane can reach 50-70%, and the selectivity of isobutene can reach 90-99%. That is, the catalyst described in the present invention is used in the reaction of dehydrogenating isobutane to prepare isobutene, and has high catalytic activity and selectivity.

[0021] Moreover, the catalyst of the present invention is easy to recover and reuse, and is less prone to coking than traditional alumina carriers. In addition, the raw materials are readily available, the cost is low, the preparation is simple, and it is suitable for industrial application. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] The first aspect of the present invention provides an isobutane dehydrogenation catalyst, the catalyst comprising a carrier and an active metal component supported on the carrier,

[0024] Wherein, the active metal component is vanadium;

[0025] Wherein, the content of the active metal component is 0.1-5wt% based on the total weight of the catalyst, calculated as metal element, for example, it can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5wt% and any range between any two values;

[0026] The carrier comprises a composite metal oxide and silicon dioxide;

[0027] Wherein, the composite metal oxide is M 1-x Al x O (x+2) / 2 , x is 0.1-0.4, for example, it can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 and any range between any two values, and M is selected from at least one of Mg, Ni and Zn.

[0028] Preferably, the content of the active metal component is 0.1-4 wt % based on the total weight of the catalyst, calculated as metal element.

[0029] Preferably, x is 0.2-0.33.

[0030] M is selected from at least one of Mg, Ni and Zn. It should be understood that the valence state of M in the composite metal oxide is +2.

[0031] The carrier can be prepared by any conventional method in the art. In a preferred embodiment of the present invention, the carrier is obtained by calcining an acidic mixture of a compound having a structure represented by formula (1) and silicon dioxide.

[0032] [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1)

[0033] Wherein, m is any number from 2 to 9 (for example, it can be 2, 4, 6, 8, 9 and any range between any two values). M and x in the present invention have the same meaning and will not be described in detail herein.

[0034] The specific operation of this method can be found in the second aspect and will not be described in detail here.

[0035] Preferably, calculated as oxide, based on the weight of the composite metal oxide, the content of silicon dioxide is 1-10wt%, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10wt% and any range between any two values, more preferably 2-8wt%.

[0036] A second aspect of the present invention provides a method for preparing an isobutane dehydrogenation catalyst, the method comprising:

[0037] (1) In the presence of an acid solution, a compound having a structure represented by formula (1) is mixed with silicon dioxide, and the mixture is molded, dried, and calcined to obtain a carrier;

[0038] (2) loading the active metal component onto the carrier obtained in step (1), and obtaining an isobutane dehydrogenation catalyst after drying and calcining;

[0039] [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1)

[0040] Wherein, M is selected from at least one of Mg, Ni and Zn; x is 0.1-0.4, for example, it can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 3 and any range between any two values, preferably 0.2-0.33; and m is any number from 2 to 9, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9 and any range between any two values;

[0041] Wherein, the active metal component is vanadium;

[0042] Wherein, calculated as metal element, the amount of the active metal component is such that, based on the total weight of the catalyst, the content of the active metal component is 0.1-5wt%, for example, it can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5wt% and any range between any two values, preferably 0.5-4wt%.

[0043] The acid solution may be an acid solution commonly used in the art. Preferably, the acid solution is a nitric acid solution.

[0044] The amount of the acid solution can be selected within a wide range. Preferably, the amount of the acid solution is 10-30 parts by weight relative to 100 parts by weight of the mixture of the compound of formula (1) and silicon dioxide.

[0045] The compound having the structure shown in formula (1) used in the present invention can be a commercial product or can be prepared according to the prior art, and its preparation technology is known to those skilled in the art, such as coprecipitation method, nucleation crystallization / isolation method, non-equilibrium crystallization method or hydrothermal synthesis method, etc. The obtained product is usually a nano-scale or submicron-scale layered dihydroxy composite metal oxide particle.

[0046] In a preferred embodiment of the present invention, the compound having the structure shown in formula (1) is prepared by a method comprising the following steps:

[0047] a) Al 3+ Water-soluble salts and M 2+ The water-soluble salt of isocyanate is mixed in the presence of an alkaline precipitant (such as NaOH and / or sodium carbonate) or urea to obtain a mixed slurry, the obtained mixed slurry is added to a crystallization kettle and stirred for crystallization to obtain a crystallized product, and then the obtained crystallized product is fully washed with deionized water to make the pH of the supernatant 7-8, and then dried at a temperature of 50-160° C. to obtain a dry product, which has a structure shown in formula (1).

[0048] As trivalent metal ion Al 3+ Water-soluble salts of 3+Nitrates, sulfates, chlorides, basic carbonates, etc., preferably nitrates.

[0049] As divalent metal ions M 2+ The water-soluble salts of 2+ Nitrates, sulfates, chlorides, basic carbonates, etc., preferably nitrates.

[0050] As the alkaline precipitant, any alkaline precipitant that can convert trivalent metal ions Al 3+ Water-soluble salts and divalent metal ions M 2+ The water-soluble salt of the precipitant is preferably an alkaline agent; preferably, a combination of an alkali and a carbonate is used. For example, the alkali can be sodium hydroxide, potassium hydroxide, ammonia water, etc., and the carbonate can be sodium carbonate, potassium carbonate, etc. Urea can also be used instead of the alkali and carbonate. The amount of the alkaline precipitant or urea can be selected within a wide range, as long as it can make Al 3+ Water-soluble salts and M 2+ The water-soluble salt can be precipitated.

[0051] The silicon dioxide described in the present invention may be silicon dioxide commonly used in the art, and may be a commercially available product.

[0052] Preferably, calculated as oxide, based on the weight of the composite metal oxide, the amount of silicon dioxide used is 1-10wt%, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10wt% and any range between any two values, preferably 2-8wt%.

[0053] The forming, drying and calcining methods can be any method in the art, and those skilled in the art can choose according to their needs, which will not be described in detail here.

[0054] Preferably, in step (1), the drying conditions include: a temperature of 100-160°C, for example, 100, 110, 120, 130, 140, 150, 160°C and any range between any two values, and a time of 2-24h, for example, 2, 6, 10, 14, 18, 20, 24h and any range between any two values.

[0055] Preferably, in step (1), the calcination conditions include: a temperature of 400-600°C, for example, 400, 450, 500, 550, 600°C and any range between any two values, and a time of 2-24h, for example, 2, 6, 10, 14, 18, 20, 24h and any range between any two values.

[0056] The method for loading the active metal component onto the carrier obtained in step (1) can be a conventional method in the art, such as the active metal component can be loaded onto the carrier by an impregnation method to obtain an isobutane dehydrogenation catalyst, which is conventional for those skilled in the art, such as the loading method described in CN1911242A, which is incorporated herein by reference.

[0057] The active metal component may be one or more of vanadium chloride, vanadyl oxalate, ammonium metavanadate and ammonium vanadate in the form of an aqueous solution in the form of an inorganic salt thereof.

[0058] Preferably, in the aqueous solution of the inorganic salt of the active metal component, the content of the inorganic salt of the active metal component is 0.5-50 g / L, for example, it can be 0.5, 1, 5, 10, 20, 30, 40, 50 g / L and any range between any two values.

[0059] Preferably, the immersion time is 6-12 hours.

[0060] Preferably, in step (2), the drying conditions include: a temperature of 100-160°C, for example, 100, 110, 120, 130, 140, 150, 160°C and any range between any two values, and a time of 2-24h, for example, 2, 6, 10, 14, 18, 20, 24h and any range between any two values.

[0061] Preferably, in step (2), the calcination conditions include: a temperature of 400-600°C, for example, 400, 450, 500, 550, 600°C and any range between any two values; a calcination time of 2-24h, for example, 2, 6, 10, 14, 18, 20, 24h and any range between any two values.

[0062] The third aspect of the present invention provides an isobutane dehydrogenation catalyst prepared by the preparation method described above.

[0063] A fourth aspect of the present invention provides use of the isobutane dehydrogenation catalyst as described above in the dehydrogenation of isobutane to prepare isobutene.

[0064] The method for preparing isobutene by dehydrogenating isobutane may include contacting and reacting the isobutane dehydrogenation catalyst as described above with isobutane.

[0065] The reaction conditions may be: temperature of 400-500°C, isobutane space velocity of 100-600h -1 .

[0066] The reaction can be carried out under normal pressure.

[0067] The reaction can be carried out in a fixed bed reactor.

[0068] The present invention will be described in detail below through examples.

[0069] 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. The pipelines of the device are all made of stainless steel pipes. The catalyst is loaded into the reaction constant temperature zone in the form of a fixed bed, and quartz sand is filled at both ends.

[0070] Silica was purchased from Inotech.

[0071] Unless otherwise specified, the reagents and materials are commercially available.

[0072] Preparation Example 1

[0073] This preparation example is used to illustrate the preparation method of the compound having the structure represented by formula (1).

[0074] [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1)

[0075] Weigh 61.51g Mg(NO3)2·6H2O and 45.03g Al(NO3)3·9H2O and dissolve them in deionized water to prepare 300mL mixed salt solution; then weigh 23.03g NaOH and 25.43g Na2CO3 and dissolve them in deionized water to prepare 300mL mixed alkali solution. Add the above two mixed solutions into the full backmixed liquid membrane reactor at the same time, adjust the slit width between the reactor rotor and the stator to 0.02mm, the working voltage to 100V, the rotor speed to 4500rpm, and mix for 2-3min to obtain a mixed slurry. Add the obtained mixed slurry into the crystallization kettle and stir, keep the temperature of the mixed slurry in the kettle at 100℃ and reflux crystallize for 6 hours to obtain a crystallized product. Wash the crystallized product thoroughly with deionized water to make the pH of the supernatant 7-8, and then dry it at 120℃ for 12 hours to obtain Mg4Al2(OH) 12 The compound shown by CO3·6H2O.

[0076] Preparation Example 2

[0077] This preparation example is used to illustrate the preparation method of the compound having the structure represented by formula (1).

[0078] [M 2+ 1-x Al x (OH)2] x+·(CO3 2- ) x / 2 ·mH2O(1)

[0079] The operation was carried out according to the method described in Preparation Example 1, except that 71.38 g Zn(NO3) was used. 2· 6H2O replaces 61.51g Mg(NO3)2·6H2O to obtain Zn4Al2(OH) 12 The compound shown by CO3·6H2O.

[0080] Preparation Example 3

[0081] This preparation example is used to illustrate the preparation method of the compound having the structure represented by formula (1).

[0082] [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1)

[0083] The method described in Preparation Example 1 was followed except that 69.77 g Ni(NO3) was used. 2· 6H2O replaces 61.51g Mg(NO3)2·6H2O to obtain Ni4Al2(OH) 12 The compound shown by CO3·6H2O.

[0084] Preparation Example 4

[0085] This preparation example is used to illustrate the preparation method of the compound having the structure represented by formula (1).

[0086] [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1)

[0087] The method described in Preparation Example 1 was followed except that 92.26 g Mg(NO3)2·6H2O was used instead of 61.51 g Mg(NO3)2·6H2O to obtain Mg6Al2(OH) 16 The compound shown by CO3·4H2O.

[0088] Examples 1-8

[0089] This example is used to illustrate the preparation method of the isobutane dehydrogenation catalyst of the present invention.

[0090] The compound having the structure shown in formula (1) prepared in Preparation Examples 1-4 was mixed with silicon dioxide, and a nitric acid solution with a concentration of 2% was added and kneaded, and extruded into strips, wherein the amount of the nitric acid solution added was 20wt% of the solid mixture. The carrier was then dried at 120°C and calcined at 500°C for 4h to obtain the carrier. The carrier was immersed in a vanadium chloride solution for 8 hours, washed, dried at 120°C, and calcined at 500°C for 12h to obtain isobutane dehydrogenation catalysts Y1-Y8, and the composition of the catalysts is shown in Table 1.

[0091] 2 g of the prepared catalyst was added to each microreactor, and the reaction temperature was controlled at 500 °C and the isobutane space velocity was 200 h -1 , the reaction produces isobutylene.

[0092] The isobutane conversion rate and isobutene selectivity of the obtained catalyst were measured. The results are shown in Table 1.

[0093] Comparative Example 1

[0094] This comparative example is used to illustrate the preparation method of a reference isobutane dehydrogenation catalyst.

[0095] The operation was carried out according to the method described in Example 1, except that SiO2 was not used. The composition of the catalyst is shown in Table 1. The results of the isobutane conversion rate and isobutene selectivity of the obtained catalyst are shown in Table 1.

[0096] Table 1

[0097]

[0098] Catalyst numbered Y3 was used to conduct a catalyst activity cycle experiment under corresponding reaction conditions, and the results are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An isobutane dehydrogenation catalyst, characterized in that The catalyst comprises a carrier and an active metal component supported on the carrier. Wherein, the active metal component is vanadium; Wherein, the content of active metal component is 0.1-5wt% based on the total weight of the catalyst in terms of metal element; The carrier comprises a composite metal oxide and silicon dioxide; Wherein, the composite metal oxide is M 1-x Al x O (x+2) / 2 , x is M 2+ / (M 2+ +Al 3+ ), x=0.1-0.4, M is selected from at least one of Mg, Ni and Zn.

2. The catalyst according to claim 1, wherein Calculated as metal elements, the content of active metal components is 0.5-4 wt % based on the total weight of the catalyst.

3. The catalyst according to claim 1 or 2, wherein x＝0.2-0.33。 4. The catalyst according to claim 1, wherein The carrier is obtained by calcining an acidic mixture of a compound having a structure represented by formula (1) and silicon dioxide. [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O(1) Wherein, m is any number from 2 to 9; Preferably, the calcination conditions include: a temperature of 400-600° C. and a time of 2-24 h.

5. The catalyst according to claim 1, wherein Calculated as oxide, based on the weight of the composite metal oxide, the content of silicon dioxide is 1-10wt%, preferably 2-8wt%.

6. A method for preparing an isobutane dehydrogenation catalyst, characterized in that: The method includes: (1) In the presence of an acid solution, a compound having a structure represented by formula (1) is mixed with a silicon dioxide source, and the mixture is molded, dried, and calcined to obtain a carrier; (2) loading the active metal component onto the carrier obtained in step (1), and obtaining an isobutane dehydrogenation catalyst after drying and calcining; [M 2+ 1-x Al x (OH)2] x+ ·(CO3 2- ) x / 2 ·mH2O (1) Wherein, M is selected from at least one of Mg, Ni and Zn; x is M 2+ / (M 2+ +Al 3+ ), x is 0.1-0.4, preferably 0.2-0.33; and m is any number from 2 to 9; Wherein, the active metal component is vanadium; Calculated as metal elements, the amount of the active metal component used is such that the content of the active metal component is 0.1-5wt%, preferably 0.5-4wt%, based on the total weight of the catalyst.

7. The preparation method according to claim 6, wherein: The acid solution is a nitric acid solution.

8. The preparation method according to claim 6, wherein: Calculated as oxide, based on the weight of the composite metal oxide, the amount of silicon dioxide used is 1-10wt%, preferably 2-8wt%.

9. The preparation method according to claim 6, wherein: In step (1), the drying conditions include: a temperature of 100-160° C. and a time of 2-24 h; and / or The calcination conditions include: a temperature of 400-600° C. and a time of 2-24 hours.

10. The preparation method according to claim 6, wherein: In step (2), the drying conditions include: a temperature of 100-160° C. and a time of 2-24 h; and / or The calcination conditions include: a temperature of 400-600° C. and a calcination time of 2-24 hours.

11. An isobutane dehydrogenation catalyst prepared by the preparation method according to any one of claims 6 to 10.

12. Use of the isobutane dehydrogenation catalyst according to any one of claims 1 to 5 and 11 in the preparation of isobutene by dehydrogenation of isobutane.

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