A catalyst for normalizing isobutane and a preparation method and application thereof

Abstract

This invention provides a catalyst for the n-assembly of isobutane, its preparation method, and its application, relating to the field of molecular sieve catalyst technology. Specifically, a microporous molecular sieve is first subjected to alkali treatment, ammonium exchange, and a first calcination to obtain a mesoporous molecular sieve; then, phosphorus species are loaded through an equal-volume impregnation treatment, followed by a second calcination to obtain a second mesoporous molecular sieve; finally, an active metal is loaded through an equal-volume impregnation treatment, followed by a third calcination to obtain the catalyst for the n-assembly of isobutane. This invention effectively solves the defects of numerous side reactions and low n-butane yield in the isobutane n-assembly reaction, contains no halogen components, and has no requirements on the moisture content of the raw materials for the isobutane n-assembly reaction, showing good application prospects.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve catalyst technology, and more specifically, to a catalyst for the normalization of isobutane, its preparation method, and its application. Background Technology

[0002] n-Butane is an important chemical raw material, widely used in the production of various organic compounds. For example, dehydrogenation produces butene and butadiene; catalytic oxidation produces maleic anhydride and acetic acid; halogenation produces halobutane; nitration produces nitrobutane; catalytic oxidation at high temperatures produces carbon disulfide; and steam reforming produces hydrogen. In current industrial production, n-butane is primarily used to produce maleic anhydride. Maleic anhydride is a commonly used and important basic organic chemical raw material, ranking as the world's third largest source of acid anhydrides after acetic anhydride and phthalic anhydride. Its downstream products have a wide range of development and applications. Because n-butane can increase the total yield of trienes by three times when used as a feedstock for the thermal cracking of ethylene, it has become an ideal thermal cracking feedstock with high added value and promising application prospects.

[0003] The normalization of isoalkanes mainly involves the following process: dehydrogenation of isoalkanes at metal active sites to form isoalkenes, followed by skeletal rearrangement at acidic sites to form n-alkenes, and finally hydrogenation to form n-alkanes. This process has several technical drawbacks, such as a long catalytic reaction time, the challenge of generating less stable secondary carbocations from relatively stable tertiary carbocations, and the need to minimize the cracking reactions of intermediate species at acidic sites, "dimerization-cracking," and condensation coking reactions to avoid excessively low n-butane selectivity and yield. Therefore, it is necessary to design a catalyst suitable for the normalization of isoalkanes, possessing good diffusivity and acidic sites with appropriate acid strength, enabling rapid normalization without deep conversion to byproducts, reducing cracking and condensation coking reactions, and thus ensuring a high n-butane yield.

[0004] Patent CN201510301472.5 discloses a method for preparing n-butane from isobutane; it uses a conventional metal-supported oxychloride as a catalyst, introduces isobutane into a normalization reactor to obtain n-butane, and then hydrogenates the product to saturate some of the olefins, thereby increasing the n-butane yield; the reaction temperature is 500℃ and the reaction pressure is 3MPa. Similarly, patent CN201810379649.7 discloses a method for preparing n-butane from mixed C4 catalysts; it uses a chlorine-containing catalyst and supports multiple metals; after desulfurization of the mixed C4 components, the raw materials are converted into n-butane under reaction conditions of 400℃ and 2.5MPa. The aforementioned existing technologies all use halogen-containing catalysts, which have the advantage of providing acidic sites with high acid strength, resulting in a high isobutane conversion rate. However, this type of catalyst requires continuous replenishment of halogens during use to address the problem of halogen loss from the catalyst and ensure that the catalyst can maintain high activity. This process causes significant technical defects due to corrosion of chemical equipment and pollution of the environment by spent catalysts. At the same time, the high reaction temperature and pressure also result in high energy consumption.

[0005] Patent CN201910654290.4 discloses a catalyst for the isobutane normalization reaction and its preparation method; it uses a large specific surface area MCM-41 molecular sieve as a support and SO42- as the catalyst. 2- A catalyst was prepared by loading noble metals onto ZrO2 as the active component. This catalyst exhibits high dispersion of acidic sites, enhancing the contact between reactants and these sites, thereby improving the conversion and selectivity of the isobutane n-assembly process. This method avoids the addition of halogens, eliminating the environmental pollution and equipment corrosion problems associated with halogens. The catalyst was tested at 330℃ and 2.0 MPa, with a WHSV of 2 h⁻¹. -1 Under reaction conditions of H2 / C4 = 200, the isobutane conversion rate is 25.7%, and the n-butane selectivity is 85.4%. However, SO4... 2- The ZrO2 component requires a high water content in the feedstock because this type of catalyst will generate SO4 under aqueous reaction conditions. 2- The loss of water can affect the activity of the catalyst, thus requiring dehydration pretreatment of the feedstock, which increases the complexity of the process and the operating cost.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The first objective of this invention is to provide a method for preparing a catalyst for the normalization of isobutane. Firstly, it addresses the need for continuous halogen replenishment to maintain the catalytic activity of halogen-containing catalysts and the negative impacts of halogens on equipment and the environment. Secondly, it addresses the technical limitation of salt-containing catalysts on the water content of the reaction feedstock. Thirdly, it addresses the technical problems of numerous side reactions, severe cracking of intermediate species, dimerization-cracking, and condensation coking reactions during the normalization of isobutane.

[0008] The second objective of this invention is to provide a catalyst for the n-assembly of isobutane, which uses a molecular sieve to provide acidic sites. This avoids the negative impact of halogens on equipment and the environment, while the molecular sieve has high thermal and hydrothermal stability and is not demanding in terms of the water content of the feedstock. By introducing mesopores into the microporous molecular sieve and modifying the acidity with phosphorus, the diffusion of the catalyst is improved and the occurrence of side reactions during the reaction is reduced, thereby improving the selectivity of the n-assembly of isobutane.

[0009] A third objective of this invention is to provide an application of a catalyst for the normalization of isobutane in the normalization of isobutane.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0011] A method for preparing a catalyst for the normalization of isobutane mainly includes the following steps:

[0012] (1) Microporous molecular sieves are subjected to alkali treatment, ammonium exchange and first calcination in sequence to obtain meso-microporous molecular sieves;

[0013] (2) The mesoporous molecular sieve is loaded with phosphorus species by equal volume impregnation treatment and then calcined to obtain a second mesoporous molecular sieve.

[0014] (3) The second mesoporous molecular sieve is loaded with active metal by equal volume impregnation treatment and then calcined to obtain a catalyst for isobutane normalization.

[0015] A catalyst for the normalization of isobutane is prepared by the method described above.

[0016] The use of the catalyst described above for isobutane normalization in the process of isobutane normalization.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] This invention provides a catalyst for the preparation of n-butane by isobutane n-assembly and its preparation method. Specifically, the catalyst is prepared by loading an active metal onto a microporous molecular sieve with introduced mesoporous structure, after acid modulation and phosphorus modification. The catalyst of this invention has high diffusivity and moderate acid strength, which significantly improves the isobutane conversion rate and n-butane selectivity.

[0019] Meanwhile, the present invention also has the following advantages: no halogen components need to be added, avoiding environmental pollution and equipment corrosion; using molecular sieves as catalyst supports has more stable thermal and hydrothermal stability, which is conducive to the long-term stable operation of the catalyst; the introduction of mesopores after alkali treatment gives the catalyst the shape selectivity of molecular sieves while also providing good diffusivity, reducing the occurrence of side reactions; after phosphorus modification, the strong acid content of the catalyst is reduced, while the medium-strong acid and weak acid content are increased, reducing the occurrence of cracking and condensation coking reactions, and ensuring a high n-butane yield. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 The XRD pattern of Embodiment 1 of the present invention is provided;

[0022] Figure 2 A aperture distribution diagram of Embodiment 1 of the present invention is provided;

[0023] Figure 3 The NH3-TPD spectrum of Example 1 of the present invention is provided;

[0024] Figure 4 SEM images of Embodiment 1 of the present invention are provided. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. The terms "a", "b", "c", "d", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] The first aspect of this invention is to provide a method for preparing a catalyst for the normalization of isobutane. The preparation method of this invention mainly includes the following three steps, the specific implementation of each step of which will be explained below.

[0027] (1) The microporous molecular sieve is subjected to alkali treatment, ammonium exchange and first calcination in sequence to obtain meso-microporous molecular sieve.

[0028] In a preferred embodiment, the microporous molecular sieve includes at least one of ZSM-5, Y, Beta, or ZSM-35.

[0029] In one preferred embodiment, the alkali treatment includes: placing the microporous molecular sieve in an alkaline aqueous solution for constant temperature water bath treatment; in some more preferred embodiments, the constant temperature water bath treatment is followed by filtration, and the pH of the filtrate is 7-9.

[0030] In a more preferred embodiment, the alkaline aqueous solution includes an aqueous solution of sodium hydroxide or potassium hydroxide; the concentration of the alkaline aqueous solution is 0.05 mol / L to 8.0 mol / L, including but not limited to any one or any two of 0.05, 0.1, 0.5, 1.0, 2.0, 3.0, 5.0, 6.0, 7.0, and 8.0 (mol / L).

[0031] In a more preferred embodiment, the temperature of the constant temperature water bath treatment is 60℃~90℃, the time of the constant temperature water bath treatment is 0.5h~4h, and the constant temperature water bath treatment is carried out under stirring.

[0032] In a more preferred embodiment, the solid-liquid ratio of the microporous molecular sieve to the alkaline aqueous solution is 0.05 to 0.2, in g / mL.

[0033] In a preferred embodiment, after the alkali treatment, the product is washed and dried before the ammonium exchange is performed; in some more preferred embodiments, the drying temperature is 80°C to 120°C.

[0034] In a preferred embodiment, the ammonium exchange and the first roasting are performed twice; that is, the first ammonium exchange is performed first, followed by the first roasting, then the second ammonium exchange, and then the second first roasting.

[0035] In a preferred embodiment, the ammonium exchange includes: placing the alkali-treated molecular sieve in an ammonium chloride solution for constant temperature standing to perform ion exchange, followed by filtration, washing, and drying.

[0036] In a more preferred embodiment, the concentration of the ammonium chloride solution is 0.8 mol / L to 1.5 mol / L.

[0037] In a more preferred embodiment, the temperature for constant temperature settling is 80℃~95℃, and the time for constant temperature settling is 1.5h~2.5h.

[0038] In a more preferred embodiment, the solid-liquid ratio of the alkali-treated molecular sieve to the ammonium chloride solution is 0.05 to 0.2, in g / mL.

[0039] In a preferred embodiment, the temperature of the first roasting is 400℃~600℃, and the roasting time is 5h~7h.

[0040] (2) The mesoporous molecular sieve is loaded with phosphorus species by equal volume impregnation treatment and then calcined to obtain a second mesoporous molecular sieve, namely an acid-modified mesoporous molecular sieve.

[0041] In a preferred embodiment, the phosphorus species includes at least one of phosphoric acid, ammonium dihydrogen phosphate, or diamine hydrogen phosphate.

[0042] The equal-volume impregnation treatment described in this invention is a method for preparing supported catalysts by using an impregnation process in which the volume of the impregnating liquid is equal to the pore volume of the solid support, so as to ensure that the impregnating liquid can just completely enter the pores of the solid support. As a preferred embodiment, the equal-volume impregnation treatment includes: fully dispersing the aqueous solution of the phosphorus species in the mesoporous molecular sieve. In some optional embodiments, those skilled in the art can make the aqueous solution fully contact the molecular sieve by means of dripping, spraying, soaking, etc., and supplement it with means of stirring, vibrating, centrifuging, etc. to achieve uniform contact.

[0043] In a more preferred embodiment, the settling time is 1 to 3 hours, and the settling is carried out at 20°C to 30°C (or room temperature).

[0044] In a preferred embodiment, the loading of the phosphorus species, based on the mass ratio of phosphorus to the mesoporous molecular sieve, is 0.5% to 5%, including but not limited to any one or any two of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0045] In a more preferred embodiment, the solvent volume of the aqueous solution of the phosphorus species is obtained by testing the water absorption rate of the mesoporous molecular sieve; it is understood that the solvent volume is equivalent to the maximum water absorption volume of the mesoporous molecular sieve.

[0046] In a preferred embodiment, the equal-volume impregnation treatment is followed by a drying treatment at a temperature of 80°C to 120°C.

[0047] In a preferred embodiment, the second calcination temperature is 400℃~600℃, and the second calcination time is 5h~7h.

[0048] (3) The second mesoporous molecular sieve is loaded with active metal by equal volume impregnation treatment and then calcined to obtain a catalyst for isobutane normalization.

[0049] In a preferred embodiment, the active metal is platinum or palladium.

[0050] In a preferred embodiment, the loading of the active metal element is 0.1% to 0.3% based on the mass ratio of the active metal element to the second mesoporous molecular sieve, including but not limited to any one or any two of 0.1%, 0.15%, 0.2%, 0.25%, and 0.3%.

[0051] The equal-volume impregnation treatment involved in this step has the same definition as step (2); similarly, the specific operation of the equal-volume impregnation treatment involved in this step is also the same as step (2); as a preferred embodiment, the equal-volume impregnation treatment includes: fully dispersing an aqueous solution containing an active metal salt in the second mesoporous molecular sieve; wherein, the active metal salt includes chloroplatinic acid (H2PtCl4) or chloroplatinic palladium (H2PdCl4).

[0052] In a preferred embodiment, the temperature of the third roasting is 400℃~600℃, and the time of the third roasting is 5h~7h.

[0053] A second aspect of the present invention is to provide a catalyst for the normalization of isobutane, which is prepared by the method for preparing the catalyst for the normalization of isobutane described in the first aspect.

[0054] A third aspect of the present invention is to provide an use of the catalyst for isobutane normalization in the field of isobutane normalization; including but not limited to a method for isobutane normalization, or a process method involving isobutane normalization, including but not limited to a mixture product comprising the catalyst for isobutane normalization, a product obtained with the catalyst for isobutane normalization, etc.; it is understood that any product or method involving the catalyst for isobutane normalization is one of the uses described in the present invention, and will not be listed individually in the present invention.

[0055] Example 1

[0056] The microporous Beta molecular sieve used in this embodiment is from Nankai University, and its model number is NKF-6-25 with SiO2 / Al2O3 = 25.

[0057] (1) Preparation of mesoporous-microporous Beta molecular sieve: 10g of Beta molecular sieve was mixed with 100mL of 0.25mol / L NaOH solution, stirred evenly, and then placed in a water bath at 70℃ for 1h. After filtration, washing, and drying, the molecular sieve was added to 1mol / L NH4Cl solution for ammonium exchange (the solid-liquid ratio of molecular sieve to solution was 1:10). Ion exchange was carried out at 90℃ for 2h. After filtration, washing, and drying, it was calcined at 550℃ for 6h. Then, the above steps of ammonium exchange, filtration, washing, drying, and calcination were repeated to obtain mesoporous-microporous Beta molecular sieve.

[0058] (2) Phosphorus modification of mesoporous Beta molecular sieve: Based on the measured water absorption rate of the mesoporous Beta molecular sieve (the water absorption rate of this sample is 90%), 5g of H-type introduced mesoporous Beta molecular sieve was prepared. According to the phosphorus loading of 0.75wt%, 0.1391g of ammonium dihydrogen phosphate was prepared into 4.5mL of aqueous solution. The solution was impregnated into 5g of H-type introduced mesoporous Beta molecular sieve in equal volume. After being placed at room temperature for 2h, it was dried and then calcined at 550℃ for 6h to obtain phosphorus-modified mesoporous Beta molecular sieve.

[0059] (3) Loading of metal Pt on phosphorus-modified mesoporous Beta molecular sieve: 2.2437 g (Pt mass fraction of 0.525%) of H2PtCl4 solution was loaded into 4 g of phosphorus-modified mesoporous Beta molecular sieve by equal volume impregnation method. After being placed at room temperature for 2 h, it was dried and then calcined at 550 °C for 6 h to obtain an isobutane normalization catalyst with a Pt loading of 0.3 wt%.

[0060] Example 2

[0061] It is basically the same as Example 1, except that the NaOH solution in step (1) is replaced with KOH solution.

[0062] Example 3

[0063] It is basically the same as Example 1, except that the concentration of NaOH solution in step (1) is replaced with 0.4 mol / L.

[0064] Example 4

[0065] It is basically the same as Example 1, except that the temperature of the water bath in step (1) is 90°C.

[0066] Example 5

[0067] It is basically the same as Example 1, except that the water bath is stirred for 2 hours in step (1).

[0068] Example 6

[0069] It is basically the same as Example 1, except that the ammonium dihydrogen phosphate in step (2) is replaced with diammonium hydrogen phosphate.

[0070] Example 7

[0071] It is basically the same as Example 1, except that the phosphorus loading in step (2) is weighed and prepared at 1 wt%.

[0072] Example 8

[0073] It is basically the same as Example 1, except that the H2PtCl4 solution in step (3) is replaced with H2PdCl4.

[0074] Example 9

[0075] This example is basically the same as Example 1, except that the microporous Beta molecule screen used in this example is from Nankai University, and its model is NKF-6-40 with SiO2 / Al2O3 = 40.

[0076] Comparative Example 1

[0077] This comparative example uses the same microporous Beta molecular sieve as Example 1. The loading method in this comparative example is the same as step (3) of Example 1; that is, only step (3) of Example 1 is performed.

[0078] Comparative Example 2

[0079] This comparative example uses the same microporous Beta molecular sieve as Example 1. The loading method of this comparative example is the same as steps (1) and (3) of Example 1; that is, only steps (1) and (3) of Example 1 are performed without step (2).

[0080] Comparative Example 3

[0081] This comparative example uses the same microporous Beta molecular sieve as Example 1. The loading method of this comparative example is the same as steps (2) and (3) of Example 1; that is, only steps (2) and (3) of Example 1 are performed without step (1).

[0082] Table 1 below shows the test results of the physicochemical properties of the catalysts in each embodiment and comparative example.

[0083] Table 1 Catalyst physical properties

[0084]

[0085] Test Example: Isobutane n-assembly test

[0086] The performance of the isobutane n-assembly reaction was evaluated using a fixed-bed microreactor, which mainly consisted of a feed section, a reaction section, and a product analysis section. The catalysts prepared in the above examples and comparative examples were independently tested. 2.0 g of catalyst (particle size 20-40 mesh) was loaded into a quartz tube (380 mm, outer diameter 16 mm, wall thickness 2 mm), and quartz wool was placed above and below the catalyst, placing it in the isothermal zone of the reactor. Before activity evaluation, the catalyst was activated at 450°C for 0.5 h in an air atmosphere, followed by purging with high-purity N2 for 10 min, then cooling to 300°C, and reducing at 300°C for 2 h in a high-purity hydrogen atmosphere. Finally, the temperature was lowered to the reaction temperature, and isobutane and hydrogen were introduced into the reactor at a specific flow rate for the reaction. Specific conditions included a temperature of 300°C, a pressure of 0.10 MPa, and a WHSV of 1 h⁻¹. -1 H2 / C4 = 1. The composition of the reaction products was analyzed using online gas chromatography.

[0087] Table 2 shows the test results of this experimental example; wherein, the isobutane conversion rate can be understood as the proportion of the introduced raw material isobutane that achieves the isomerization reaction; the n-butane selectivity can be understood as the proportion of n-butane generated from the isomerized isobutane; and the n-butane yield is the product of the isobutane conversion rate and the n-butane selectivity.

[0088] Table 2. Results of the Experiment

[0089] name Isobutane conversion rate, % n-Butane selectivity, % n-Butane yield, % Example 1 31.36 86.12 27.01 Example 2 31.13 86.22 26.84 Example 3 33.15 73.61 24.40 Example 4 33.86 71.91 24.35 Example 5 33.96 74.85 25.42 Example 6 30.28 84.69 25.64 Example 7 12.99 83.56 10.85 Example 8 30.28 85.73 25.96 Example 9 23.55 82.84 19.51 Comparative Example 1 35.85 68.04 24.39 Comparative Example 2 36.44 71.79 26.16 Comparative Example 3 32.03 80.52 25.79

[0090] like Figure 1, Figure 2 , Figure 3 The diagram shows the detection results of Example 1 and Comparative Examples 1-3; wherein, Figures 1-3 In the text, "ISO-1" corresponds to the catalyst sample of Example 1, "D-ISO-1" corresponds to the catalyst sample of Comparative Example 1, "D-ISO-2" corresponds to the catalyst sample of Comparative Example 2, and "D-ISO-3" corresponds to the catalyst sample of Comparative Example 3. Figure 4 SEM images of the catalyst sample from Example 1 are provided.

[0091] Figure 1 The XRD patterns of Example 1 and three comparative examples are shown. The figures show that all four samples exhibit distinct characteristic diffraction peaks belonging to Beta molecular sieves. Comparison of the baseline smoothness and peak intensities reveals that although Example 1 and Comparative Example 2 underwent alkali treatment to desilicate and introduce mesopores, their crystal structure remained relatively intact. Comparative Example 3, after phosphorus modification, also maintained its original crystallinity level. This demonstrates that by employing mild alkali treatment and phosphorus modification conditions, the present invention can achieve modulation of pore structure and acid properties while ensuring a relatively complete catalyst crystal structure.

[0092] Figure 2 The diagram illustrates the pore structure properties of Example 1 and three comparative examples. The pore size distribution diagrams show that the pore size distribution of samples from Example 1 and Comparative Example 2 (below 10 nm) is significantly higher than that of Comparative Example 1 and Comparative Example 3. This indicates that the samples introduced with alkali treatment have larger pore sizes, which is beneficial for improving the diffusion performance of the catalyst and reducing the probability of intermediate species being deeply converted into byproducts. Meanwhile, Table 1 shows that the mesopore volume of Example 1 and Comparative Example 2 is 33% higher than that of Comparative Example 1 and Comparative Example 3. This indicates that phosphorus modification has little effect on the pore structure of the catalyst; its main effect is to modulate the acid properties of the catalyst.

[0093] Figure 3 The figure shows the NH3-TPD chromatograms of Example 1 and three comparative examples. The figures show three desorption peaks of NH3 at approximately 200℃, 350℃, and 520℃, representing the weak acid, medium-strong acid, and strong acid in the catalyst, respectively. The weak acid peak temperatures of the phosphorus-modified samples of Example 1 and Comparative Example 3 are higher than those of the unmodified Comparative Examples 1 and 2, and the medium-strong acid content of the phosphorus-modified samples is significantly increased. Meanwhile, Table 1 shows the data on the strong acid content and total acid content of the catalysts; both the total acid content and the strong acid content of the samples are significantly reduced after phosphorus modification.

[0094] It is evident that this invention enhances the acid strength of the weak and moderately strong acids in the catalyst through phosphorus modification, thereby reducing the proportion of strong acids in the catalyst. Strong acids are essential in the isobutane n-assembly reaction; a high amount of strong acid is beneficial for increasing the conversion rate, but it also increases the probability of side reactions and reduces product selectivity. Combined with the data in Table 2, although the conversion rate decreases slightly after moderate phosphorus modification, the improvement in product selectivity is greater, which is beneficial for improving the overall product yield. Furthermore, the introduction of mesopores into the microporous molecular sieve improves the diffusion performance of the catalyst, enhances the mass transfer efficiency of the catalyst bulk phase, reduces the occurrence of intermediate species cracking reactions, "dimerization-cracking," and condensation coking reactions, and improves the selectivity of n-butane. Example 1 shows a transfer rate of 31.36%, a selectivity of 86.12%, and a yield of 27.01%, demonstrating good application prospects.

[0095] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. The use of a catalyst in the n-assembly of isobutane, characterized in that, The preparation method of the catalyst includes the following steps: (1) The microporous molecular sieve is subjected to alkali treatment, ammonium exchange and first calcination in sequence to obtain meso-microporous molecular sieve; (2) The mesoporous molecular sieve is loaded with phosphorus species by equal volume impregnation treatment and then calcined to obtain a second mesoporous molecular sieve. (3) The second mesoporous molecular sieve is loaded with active metals by equal volume impregnation treatment and then calcined to obtain a catalyst for isobutane normalization. The microporous molecular sieve is Beta, and the active metal is platinum or palladium.

2. The use according to claim 1, characterized in that, The alkaline treatment includes placing the microporous molecular sieve in an alkaline aqueous solution for constant temperature water bath treatment.

3. The use according to claim 2, characterized in that, The alkaline aqueous solution includes an aqueous solution of sodium hydroxide or potassium hydroxide, and the concentration of the alkaline aqueous solution is 0.05 mol / L to 8.0 mol / L.

4. The use according to claim 2, characterized in that, The temperature of the constant temperature water bath treatment is 60℃~90℃, and the treatment time is 0.5h~4h.

5. The use according to claim 1, characterized in that, The ammonium exchange includes: placing the alkali-treated molecular sieve in an ammonium chloride solution for constant temperature and static setting to perform ion exchange, followed by filtration, washing, and drying.

6. The use according to claim 5, characterized in that, The concentration of the ammonium chloride solution is 0.8 mol / L to 1.5 mol / L.

7. The use according to claim 5, characterized in that, The constant temperature settling temperature is 80℃~95℃, and the constant temperature settling time is 1.5h~2.5h.

8. The use according to claim 1, characterized in that, Step (1) includes: subjecting the microporous molecular sieve to the alkali treatment, then performing the first ammonium exchange and the first first calcination, and then performing the second ammonium exchange and the second first calcination to obtain a mesoporous molecular sieve.

9. The use according to claim 1, characterized in that, The phosphorus species include at least one of phosphoric acid, ammonium dihydrogen phosphate, or diammonium hydrogen phosphate.

10. The use according to claim 1, characterized in that, The equal-volume impregnation treatment includes: fully dispersing the aqueous solution in the mesoporous molecular sieve or the second mesoporous molecular sieve, and the volume of the aqueous solution is the same as the maximum water absorption volume of the mesoporous molecular sieve or the second mesoporous molecular sieve.

11. The use according to claim 1, characterized in that, The loading of phosphorus species is 0.5% to 5% based on the mass ratio of phosphorus to the mesoporous molecular sieve. And / or, the loading of the active metal is 0.1% to 0.3% based on the mass ratio of the active metal element to the second mesoporous molecular sieve.

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