Isobutane normalizing catalyst, preparation method thereof and isobutane normalizing method

Abstract

The invention relates to the technical field of catalysts, and discloses an isobutane normalizing catalyst and a preparation method thereof, and an isobutane normalizing method, the catalyst comprises a carrier, and an active metal component and an acidic component loaded on the carrier; the carrier is spherical aluminum oxide, the spherical aluminum oxide has bimodal pore distribution of macropores and small pores, the most probable pore diameter of the small pores is 2-10nm, and the most probable pore diameter of the macropores is 11-18nm; in the spherical aluminum oxide, the pore volume of small pores accounts for 15-70% of the total pore volume, and the pore volume of large pores accounts for 30-85% of the total pore volume; the active metal component is selected from at least one of VIII group metals, and the acidic component is chlorine; on the basis of the weight of the carrier, in terms of elements, the content of the active metal component is 0.01-1 wt%, and the content of the acidic component is 0.5-1.8 wt%. The catalyst has high normalizing activity, selectivity and stability in an isobutane normalizing reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to an isobutane normalization catalyst and its preparation method, and an isobutane normalization method. Background Technology

[0002] n-Butane is a high-quality feedstock for ethylene cracking. Compared with isobutane, it has the advantages of higher triene yield and less methane by-product. n-Butane is also a feedstock for the oxidation process to produce maleic anhydride. In recent years, in order to save energy, reduce consumption, and improve market competitiveness, there has been a clear trend towards larger-scale plants and lighter feedstocks, resulting in a significant shortage of ethylene cracking feedstocks. Increasing n-Butane production has become an important option to make up for the shortage of ethylene cracking feedstocks.

[0003] CN104892339A discloses a method for preparing n-butane from isobutane. The catalyst used includes a support, an active component, and an acidic component. The support is a mixture of one or more heat-resistant oxides, the active component is composed of one or more Group VIII transition elements, and the acidic component is a chloride. At a reaction temperature of 500℃, a reaction pressure of 3.0 MPa, and a hydrogen-to-isobutane molar ratio of 2.2:1, the single-pass conversion of isobutane is ≥40%, and the selectivity of n-butane is ≥85%. However, this method requires a high hydrogen-to-hydrogen molar ratio.

[0004] CN107285977A discloses a system apparatus for preparing n-butane by isobutane normalization. The normalization catalyst includes a support, an active component, and an auxiliary agent. The support is composed of a heat-resistant oxide or a mixed oxide. The normalization conditions allow at least 40% of the isobutane-containing material to be normalized. However, the normalization reaction product also contains isobutene, 1-butene, 2-butene, and propylene, which need to be fed into a hydrogenation reactor for hydrogenation to saturate the olefins.

[0005] The current isobutane normalization reaction temperature is usually above 400℃. At high temperatures, the catalyst coking rate is accelerated and the regeneration cycle is shortened. When using fixed-bed process and strip-shaped isobutane normalization catalyst, catalyst regeneration is frequent, which affects the stability of unit operation and the economic efficiency of the technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low catalyst activity, poor selectivity, and frequent regeneration in the prior art, and to provide an isobutane normalization catalyst and its preparation method, as well as an isobutane normalization method. This catalyst has high normalization activity, selectivity and good regeneration performance.

[0007] To achieve the above objectives, the present invention provides an isobutane normalization catalyst, the catalyst comprising a support and an active metal component and an acidic component supported on the support;

[0008] The carrier is spherical alumina, which has a bimodal pore distribution of macropores and micropores. The most probable diameter of the micropores is 2-10 nm, and the most probable diameter of the macropores is 11-18 nm. In the spherical alumina, the pore volume of the micropores accounts for 15-70% of the total pore volume, and the pore volume of the macropores accounts for 30-85% of the total pore volume.

[0009] The active metal component is selected from at least one group VIII metal, and the acidic component is chlorine;

[0010] Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

[0011] A second aspect of this invention provides a method for preparing an isobutane n-assembly catalyst, comprising the following steps:

[0012] (1) Mix the first alumina precursor with a most probable pore diameter of 3-8 nm and the second alumina precursor with a most probable pore diameter of 10-35 nm with a colloid solvent to obtain alumina sol.

[0013] The mass ratio of the first alumina precursor to the second alumina precursor is 0.1-12:1.

[0014] (2) Under stirring conditions, the alumina sol was mixed with the surfactant;

[0015] (3) The mixture obtained in step (2) is drop-ball shaped, then dried and calcined to obtain a carrier;

[0016] (4) Loading an active metal component and an acidic component onto the carrier; the active metal component is selected from at least one group VIII metal, and the acidic component is chlorine;

[0017] Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

[0018] A third aspect of the present invention provides a method for isobutane normalization, the method comprising: contacting an isobutane feedstock with a catalyst in the presence of hydrogen under isobutane normalization reaction conditions;

[0019] The catalyst is the isobutane normalization catalyst described in the first aspect or the isobutane normalization catalyst prepared by the preparation method described in the second aspect.

[0020] Preferably, the isobutane normalization reaction conditions include: a reaction temperature of 380-480℃, preferably 400-470℃; a reaction pressure of 0.5-5 MPa, preferably 0.9-3.5 MPa; a hydrogen / hydrocarbon molar ratio of 0.01-0.9, preferably 0.05-0.8; and a mass hourly space velocity (HHSV) of 0.5-5 h⁻¹ for the isobutane feedstock. -1 Preferably 0.8-4h -1 .

[0021] The isobutane normalization catalyst provided by the present invention comprises a spherical alumina support with a bimodal pore distribution. The support has a suitable pore size distribution. The support is loaded with active metal components and acidic components, which is beneficial to exert the optimized synergistic effect of the catalyst metal center and acid center. The catalyst has high normalization activity, selectivity and stability in the isobutane normalization reaction. Attached Figure Description

[0022] Figure 1 These are XRD patterns of the carriers prepared in the embodiments and comparative examples of the present invention;

[0023] Figure 2 This is a pore distribution diagram of the carriers prepared in the embodiments and comparative examples of the present invention;

[0024] Figure 3 This is a comparison chart of the isobutane normalization stability of the catalysts in the embodiments and comparative examples of the present invention. Detailed Implementation

[0025] 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.

[0026] The first aspect of the present invention provides an isobutane normalization catalyst, the catalyst comprising a support and an active metal component and an acidic component supported on the support;

[0027] The carrier is spherical alumina, which has a bimodal pore distribution of macropores and micropores. The most probable diameter of the micropores is 2-10 nm, and the most probable diameter of the macropores is 11-18 nm. In the spherical alumina, the pore volume of the micropores accounts for 15-70% of the total pore volume, and the pore volume of the macropores accounts for 30-85% of the total pore volume.

[0028] The active metal component is selected from at least one group VIII metal, and the acidic component is chlorine;

[0029] Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

[0030] According to the present invention, the isobutane normalization catalyst comprises a spherical alumina support with a bimodal pore distribution. The support has a suitable pore size distribution, with the pore volumes of macropores and micropores within the aforementioned range. Combined with the supported active metal component and acidic component, it is beneficial to exert the optimized synergistic effect of the catalyst's metal center and acid center. The catalyst exhibits high normalization activity, selectivity, and good regeneration performance in the isobutane normalization reaction.

[0031] In this invention, based on the weight of the support, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight. Preferably, based on the weight of the support, the content of the active metal component is 0.03-0.5% by weight, and the content of the acidic component is 0.8-1.5% by weight. Under the above-mentioned preferred catalyst composition, it is beneficial to further improve the optimized synergy between the catalyst metal center and the acid center, thereby exhibiting higher ortho-configuration activity and selectivity in the reaction.

[0032] According to some preferred embodiments of the present invention, the mass ratio of the active metal component to the acidic component, based on elements, is 1:(3-30), preferably 1:(3-27), and more preferably 1:(3.2-10).

[0033] In this invention, the size range of the spherical alumina is relatively wide. Preferably, the diameter of the spherical alumina is 1.6-2.2 mm, and more preferably 1.65-2.05 mm. Under these preferred conditions, it is beneficial for the catalyst to be transported and circulated in the moving bed reaction and regeneration system, further improving the efficiency of the isobutane n-assembly reaction.

[0034] According to some preferred embodiments of the present invention, in the spherical alumina, the most probable pore diameter of the micropores is 3-9.5 nm, and the most probable pore diameter of the macropores is 12-17 nm. In the above preferred embodiments, it is beneficial to further increase the density of ortho-configuration active centers, facilitate the diffusion of reactants, further reduce secondary reactions, and improve ortho-configuration activity and selectivity.

[0035] According to some preferred embodiments of the present invention, in the spherical alumina, the pore volume of the small holes accounts for 20-50% of the total pore volume, and the pore volume of the large holes accounts for 50-80% of the total pore volume.

[0036] According to the present invention, preferably, the pore volume of the spherical alumina is 0.4-0.65 mL / g, more preferably 0.45-0.63 mL / g.

[0037] According to the present invention, preferably, the specific surface area of ​​the spherical alumina is 170-240 m². 2 / g, preferably 190-230m 2 / g.

[0038] In this invention, the specific surface area and pore structure of the support were characterized using a Micromeritics ASAP2400 surface area analyzer. Sample pretreatment conditions were: 250℃, 1.3 Pa, 4 h. The N2 adsorption-desorption isotherms of the catalyst were determined using the low-temperature nitrogen static capacity adsorption method. The specific surface areas of the catalyst and support were calculated using the BET formula. The N2 adsorption amount at p / p0 = 0.98 was taken as the sample pore volume, and the pore size distribution of the catalyst and support was calculated using the BJH method.

[0039] In this invention, the active metal component is selected from at least one group VIII metal, and can be any one or more group VIII noble metal elements or group VIII non-noble metal elements. For example, it can be at least one of Fe, Co, Ni, Ru, Rh, Pd, and Pt. Preferably, the active metal component is selected from at least one group VIII noble metal element, preferably at least one of Pt, Ru, and Pd, and more preferably Pt and / or Pd. Using the above-mentioned preferred active metal component in combination with the acidic component Cl is beneficial to further improve the optimized synergy between the catalyst metal center and the acid center.

[0040] A second aspect of this invention provides a method for preparing an isobutane n-assembly catalyst, comprising the following steps:

[0041] (1) Mix the first alumina precursor with a most probable pore diameter of 3-8 nm and the second alumina precursor with a most probable pore diameter of 10-35 nm with a colloid solvent to obtain alumina sol.

[0042] The mass ratio of the first alumina precursor to the second alumina precursor is 0.1-12:1.

[0043] (2) Under stirring conditions, the alumina sol was mixed with the surfactant;

[0044] (3) The mixture obtained in step (2) is drop-ball shaped, then dried and calcined to obtain a carrier;

[0045] (4) Loading an active metal component and an acidic component onto the carrier; the active metal component is selected from at least one group VIII metal, and the acidic component is chlorine;

[0046] Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

[0047] In this invention, the terms "first" and "second" in "first alumina precursor" and "second alumina precursor" are used only to distinguish alumina precursors with different most probable pore diameters. There are no particular limitations on their mixing order or types. The alumina precursor can be selected from any substance that can be calcined to obtain alumina, as is well known to those skilled in the art, as long as it meets the aforementioned requirement of most probable pore diameter. Preferably, the first alumina precursor and the second alumina precursor are each independently selected from at least one of aluminum hydroxide, boehmite, and gibbsite, with aluminum hydroxide being the most preferred.

[0048] According to the present invention, the most probable pore diameter of the first alumina precursor is 3-8 nm, preferably 3.5-7 nm. The most probable pore diameter of the second alumina precursor is 10-35 nm, preferably 11-32 nm. Using the above-preferred alumina precursor is beneficial for forming a carrier with a suitable bimodal pore distribution.

[0049] According to the present invention, preferably, in step (1), the pore volume of the first alumina precursor is 0.2-0.5 mL / g, more preferably 0.21-0.42 mL / g.

[0050] Preferably, the pore volume of the second alumina precursor is 0.55-1 mL / g, and more preferably 0.75-0.95 mL / g.

[0051] Using the preferred combination of the first and second alumina precursors described above is beneficial for further improving the activity and selectivity of the prepared catalyst.

[0052] According to the present invention, the mass ratio of the first alumina precursor to the second alumina precursor is 0.1-12:1, for example, it can be a specific but not limiting mass ratio or any range between two such ratios, such as 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1. Preferably, the mass ratio of the first alumina precursor to the second alumina precursor is 0.15-7:1. Using the above-mentioned preferred raw material ratio is beneficial for adjusting the ratio of macropores and micropores in the obtained spherical alumina, further improving the catalytic activity of the catalyst.

[0053] The present invention has a wide range of choices for the adhesive solvent. Preferably, the adhesive solvent is an aqueous solution of an acid. The acid can be any conventional organic acid and / or inorganic acid. For example, the inorganic acid can be at least one of nitric acid, hydrochloric acid, and perchloric acid. For example, the organic acid can be at least one of tartaric acid, lactic acid, citric acid, gluconic acid, formic acid, and acetic acid.

[0054] According to the present invention, preferably, the concentration of acid in the adhesive solvent is 15-25 wt%.

[0055] Preferably, the ratio of the mass of acid in the colloidal solvent to the total mass of the first alumina precursor and the second alumina precursor is 0.03-0.15:1, more preferably 0.04-0.1:1.

[0056] According to the present invention, a suitable solvent may be introduced during the mixing process in step (1) to ensure that the solid content in the alumina sol, calculated as alumina, meets the above-mentioned range. The solvent may be water.

[0057] According to the present invention, preferably, the surfactant is a fatty alcohol polyoxyethylene ether. Its chemical structure can be represented as RO-(CH2CH2). n H, where R is a hydrocarbon group, preferably a C10-C20 hydrocarbon group; n is 7-11. The surfactant is commercially available.

[0058] Preferably, the amount of surfactant added is 0.5-2 wt%, more preferably 0.6-1.8 wt%, based on the total mass of the first alumina precursor and the second alumina precursor.

[0059] In order to adjust the pore distribution, control the volume and bulk density of the alumina carrier, an optional pore expander may be added during the mixing process described in step (1). The pore expander may be selected from at least one of gasoline, kerosene and diesel.

[0060] Preferably, the amount of pore-expanding agent added is 1-9 wt%, more preferably 2-8 wt%, based on the total mass of the first alumina precursor and the second alumina precursor.

[0061] According to some preferred embodiments of the present invention, the drop ball forming method in step (3) includes: dropping the mixture obtained in step (2) into an oil-ammonia column composed of an oil layer and an ammonia water layer, and curing for 0.5-5 hours. In this process, the mixture first forms small balls in the oil phase of the oil-ammonia column, and the small balls pass through the oil-water interface into the ammonia water layer and are cured into alumina wet balls, with a curing time of 0.5-5 hours.

[0062] Preferably, the oil phase in the oil layer of the oil-ammonia column is a C10-C14 alkane. Preferably, the oil phase can be provided by kerosene.

[0063] Preferably, the mass fraction of ammonia in the ammonia layer of the oil-ammonia column is 4-15 wt%, more preferably 6-12 wt%.

[0064] According to some preferred embodiments of the present invention, the thickness of the oil layer in the oil-ammonia column is 2-20 cm, preferably 4-20 cm.

[0065] According to some preferred embodiments of the present invention, the thickness of the ammonia water layer in the oil-ammonia column is 30-150cm, preferably 50-80cm.

[0066] According to the present invention, the preparation method further includes: drying and calcining the wet balls obtained by drop ball forming. Preferably, the drying temperature is 60-150℃, more preferably 100-120℃, and the drying time is 0.5-24h, more preferably 1-12h.

[0067] Preferably, the roasting temperature in step (3) is 400-700℃, more preferably 500-650℃, and the roasting time is 0.5-24h, more preferably 2-8h.

[0068] The present invention does not have any particular limitation on the specific loading method in step (4), as long as the amount of active metal component and acid component is satisfied.

[0069] According to some preferred embodiments of the present invention, in step (4), the method of loading the active metal component and the acid component onto the carrier includes: contacting the carrier with an impregnation solution containing chloride of active metal component, and then drying and calcining.

[0070] This invention does not impose particular limitations on the manner and conditions of contact between the carrier and the impregnation solution, as long as the aforementioned loading objective can be achieved. Preferably, the concentration of the impregnation solution containing the chloride of the active metal component is 0.1-1.3 wt%, more preferably 0.2-0.8 wt%. In this invention, the concentration of the impregnation solution refers to the percentage of the mass of the active metal component (in elemental terms) to the total mass of the impregnation solution.

[0071] According to some preferred embodiments of the present invention, the mass ratio of the impregnation solution to the alumina carrier is (0.5-2):1, preferably (0.8-1.2):1.

[0072] To further improve the dispersion of the metal centers, the impregnation solution preferably also contains a competitive adsorbent, which is preferably at least one of hydrochloric acid, trichloroacetic acid, and nitric acid.

[0073] Preferably, the mass ratio of the amount of the competing adsorbent to the amount of the chloride of the active metal component is (2-25):1, more preferably (4-20):1.

[0074] Preferably, the contact temperature is 10-70℃ and the contact time is 0.5-10h.

[0075] Preferably, the drying temperature of the carrier after impregnation is 80-140℃, more preferably 100-130℃, and the drying time is 5-30h, more preferably 8-24h.

[0076] Preferably, the calcination temperature of the carrier after impregnation is 450-650℃, more preferably 480-600℃, and the calcination time is 1-10h, more preferably 3-5h.

[0077] According to the present invention, preferably, the preparation method further includes: reducing the product obtained in step (4) in the presence of hydrogen. Those skilled in the art can also perform catalyst reduction before the reaction as needed, and the present invention does not particularly limit this.

[0078] The present invention does not impose any particular limitation on the specific conditions of the reduction treatment, as long as at least a portion of the active metal components can be reduced to elemental form, which is well known to those skilled in the art.

[0079] Preferably, the reduction treatment conditions include: a reduction temperature of 400-600℃, more preferably 450-550℃, a reduction time of 1-10h, more preferably 3-5h, and a gas-agent volume ratio of 300-1500, more preferably 400-1200.

[0080] A third aspect of the present invention provides a method for isobutane normalization, the method comprising: contacting an isobutane feedstock with a catalyst in the presence of hydrogen under isobutane normalization reaction conditions;

[0081] The catalyst is the isobutane normalization catalyst described in the first aspect or the isobutane normalization catalyst prepared by the preparation method described in the second aspect.

[0082] In this invention, the isobutane normalization catalyst prepared by the preparation method provided in the first or second aspect above exhibits high isobutane normalization activity and selectivity under relatively low hydrogen-to-hydrogen molar ratio conditions (hydrogen-to-hydrogen molar ratio less than 1). In contrast, conventional isobutane normalization reactions in the prior art typically use a hydrogen-to-hydrogen molar ratio of 1 or higher.

[0083] Preferably, the isobutane normalization reaction conditions include: a reaction temperature of 380-480℃, preferably 400-470℃; a reaction pressure of 0.5-5 MPa, preferably 0.9-3.5 MPa; a hydrogen / hydrocarbon molar ratio of 0.01-0.9, preferably 0.05-0.8; and a mass hourly space velocity (HHSV) of 0.5-5 h⁻¹ for the isobutane feedstock. -1 Preferably 0.8-4h-1 The preferred embodiments described above are beneficial for further improving the ortho-configuration activity and selectivity of the reaction.

[0084] In this invention, the range of isobutane raw materials is relatively wide, and the isobutane raw materials may also contain a small amount of impurities, such as olefins, C5+ alkanes, water, sulfur, etc.

[0085] Preferably, the isobutane feedstock has an olefin content of less than 1% by mass, more preferably less than 0.5% by mass; a C5+ alkane content of less than 1.5% by mass, more preferably less than 1.0% by mass; a water content of less than 5 ppmw, more preferably less than 3 ppmw; and a sulfur content of less than 10 ppmw, more preferably less than 5 ppmw.

[0086] Preferably, the isobutane content in the isobutane raw material is not less than 80%, more preferably not less than 90%, and even more preferably not less than 95%.

[0087] The method provided by this invention can be applied to various conventional reactors in the art, and preferably, the method is carried out in a moving bed reactor.

[0088] The present invention will be described in detail below through embodiments.

[0089] The aluminum hydroxide powder used in the following preparation examples was purchased from Sasol, and its pore characteristics are shown in Table 1.

[0090] Table 1

[0091] Aluminum hydroxide powder number <![CDATA[BET specific surface area, m 2 / g]]> Pore ​​volume, mL / g Most possible aperture diameter, nm YL-1 308 0.348 3.9 YL-2 216 0.563 11.6 YL-3 306 0.222 4.0 YL-4 141 0.899 30.5

[0092] Example 1

[0093] (1) 40.0 g of aluminum hydroxide powder YL-1 (alumina content 75.0% by mass) and 60.0 g of aluminum hydroxide powder YL-2 (alumina content 72.6% by mass) were mixed evenly. The specific surface area and pore volume of YL-1 and YL-2 are shown in Table 1. 220 g of deionized water was added to the above powder, and the mixture was stirred for 0.5 h. Then, 25.0 g of a 15.3% by mass nitric acid aqueous solution was added dropwise, and the mixture was stirred for 2 h to obtain aluminum hydroxide sol, in which the solid content based on alumina was 18% by mass. 1.0 g of fatty alcohol polyoxyethylene ether (commercially purchased, brand name AEO-9, general formula RO-(CH2CH2)) was added to the aluminum hydroxide sol. n H(R=C 12 ~ 18 (n=9)) Stir for 1 hour to prepare a sol for droplets.

[0094] (2) Preparation of Al2O3 microsphere carriers

[0095] The prepared sol was dropped into an oil-ammonia column. The oil layer in the oil-ammonia column was kerosene with a thickness of 15 cm, and the ammonia layer was 70 cm thick. The kerosene used contained C. 10 ~C 14 The alkanes, with a distillation range of 170-225℃, and the ammonia concentration of 10% by mass, were used. The sol solution was dropped into the kerosene layer to form spheres, which passed through the oil-water interface and solidified in the ammonia layer for 1 hour. The wet spheres were then removed, dried at 110℃ for 2 hours, and calcined at 560℃ for 4 hours to obtain Al2O3 microsphere carrier ZT-1, with a diameter of 1.65 mm.

[0096] The XRD characterization results of ZT-1 are shown in [reference needed]. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 It can be seen that ZT-1 exhibits a bimodal distribution, with most probable pore diameters of 8.2 nm and 13.4 nm, respectively.

[0097] (3) Preparation of catalyst

[0098] Take 50.0g of the microsphere support ZT-1 and add it to 55.0g of an aqueous solution containing 0.125g Pt, chloroplatinic acid, 1% trichloroacetic acid, and 3% hydrochloric acid. Soak the sample at 25℃ for 1h, then evaporate the water in the solution to dryness, and dry it at 110℃ for 12h. Then, load the dried sample into a tubular reactor and treat it with gas. The gas / agent volume ratio during treatment is 800. The specific steps are as follows: first, purge with nitrogen at 220℃ for 2h, then switch to air and activate at 530℃ for 4h, then replace with nitrogen for 0.5h, and finally reduce with hydrogen at 500℃ for 4h to obtain catalyst cat-1. The Pt and Cl content characterization results of catalyst cat-1 are shown in Table 3.

[0099] Example 2

[0100] (1) Preparation of aluminum hydroxide sol

[0101] 70.0 g of aluminum hydroxide powder YL-3 (alumina content 74.9% by mass) and 30.0 g of aluminum hydroxide powder YL-4 (alumina content 72.7% by mass) were mixed evenly. The specific surface area and pore volume of YL-3 and YL-4 are shown in Table 1. 180 g of deionized water was added to the above powder, and the mixture was stirred for 0.5 h. Then, 20.0 g of 18.0% by mass nitric acid aqueous solution was added dropwise, and the mixture was stirred for 2 h to obtain aluminum hydroxide sol, in which the solid content (calculated as alumina) was 20% by mass. 0.5 g of fatty alcohol polyoxyethylene ether was added to the aluminum hydroxide sol, and the mixture was stirred for 1 h to prepare a sol for drop ball preparation.

[0102] (2) Preparation of Al2O3 microsphere carriers

[0103] The prepared sol was dropped into an oil-ammonia column. The oil layer in the oil-ammonia column was kerosene with a thickness of 14 cm, and the ammonia layer was 65 cm thick. The kerosene used contained C. 10 ~C 14 Alkanes with a distillation range of 170-225℃ and an ammonia concentration of 10% by mass were used. The sol solution was dropped into a kerosene layer to form spheres, which then passed through the oil-water interface and solidified in the ammonia layer for 1 hour. The wet spheres were then removed, dried at 110℃ for 2 hours, and calcined at 570℃ for 4 hours to obtain Al₂O₃ microsphere carrier ZT-2, with a diameter of 2 mm. The XRD characterization results of ZT-2 are shown below. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 It can be seen that ZT-2 exhibits a bimodal distribution, with most probable pore diameters of 3.4 nm and 16.4 nm, respectively.

[0104] (2) Preparation of catalyst

[0105] Take 50.0g of the microsphere support ZT-2 and add it to 55.0g of an aqueous solution containing 0.125g Pt of chloroplatinic acid, 1% trichloroacetic acid and 3% hydrochloric acid. Soak at 25℃ for 1h, then evaporate the water in the solution to dryness, dry at 110℃ for 12h, and then load the dried sample into a tubular reactor for gas treatment. The gas / agent volume ratio during treatment is 800. The specific steps are as follows: first, purge with nitrogen at 220℃ for 2h, then switch to air and activate at 530℃ for 4h, then replace with nitrogen for 0.5h, and finally reduce with hydrogen at 500℃ for 4h to obtain catalyst cat-2. The physicochemical characterization results of catalyst cat-2 are shown in Table 3.

[0106] Example 3

[0107] The method of Example 1 is different except that the amount of chloroplatinic acid added in step (3) is 0.025 g Pt, and catalyst cat-3 is prepared. The physicochemical characterization results of catalyst cat-3 are shown in Table 3.

[0108] Example 4

[0109] The method is the same as in Example 1, except that in step (1), the amount of aluminum hydroxide powder YL-1 is 9g and the amount of aluminum hydroxide powder YL-2 is 91g. The resulting spherical alumina carrier is designated as ZT-3.

[0110] Catalyst cat-4 was prepared, and the physicochemical characterization results of catalyst cat-4 are shown in Table 3.

[0111] Example 5

[0112] The method of Example 1 was followed, except that in step (1), the amount of aluminum hydroxide powder YL-1 was 92g and the amount of aluminum hydroxide powder YL-2 was 8g. The spherical alumina support was prepared and designated as ZT-4. Catalyst cat-5 was prepared, and the physicochemical characterization results of catalyst cat-5 are shown in Table 3.

[0113] Comparative Example 1 - Without Pt

[0114] Following the method of Example 1, except that chloroplatinic acid was not added during impregnation in step (3), catalyst Dcat-1 was prepared. The physicochemical characterization results of catalyst Dcat-1 are shown in Table 3.

[0115] Comparative Example 2 - High Chlorine Content

[0116] Take 20.0g of catalyst cat-1 prepared in Example 1, and introduce sublimated AlCl3 vapor into the reactor containing catalyst cat-1 using H2 as the carrier gas to chlorinate the catalyst precursor. The amount of AlCl3 used is 2.0g, the chlorination temperature is 500℃, the chlorination time is 45min, and the gas / catalyst volume ratio of H2 to catalyst precursor is 500. After chlorination, continue to pass H2 to cool down to room temperature to obtain catalyst Dcat-2. The physicochemical characterization results of catalyst Dcat-2 are shown in Table 3.

[0117] Comparative Example 3

[0118] The method is the same as in Example 1, except that YL-2 is not added in step (1), and the amount of aluminum hydroxide powder YL-1 is 100g. The Al2O3 microsphere carrier DZT-1, and the XRD characterization results of DZT-1 are shown below. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 From this, it can be seen that DZT-1 exhibits a single-peak distribution, with the most probable pore diameter being 6.6 nm.

[0119] Catalyst Dcat-3 was prepared, and the physicochemical characterization results of catalyst Dcat-3 are shown in Table 3.

[0120] Comparative Example 4

[0121] The method is the same as in Example 1, except that YL-1 is not added in step (1), and the amount of aluminum hydroxide powder YL-2 is 100g. The Al2O3 microsphere carrier DZT-2, and the XRD characterization results of DZT-2 are shown below. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 From this, it can be seen that DZT-2 exhibits a single-peak distribution, with the most probable pore diameter being 9.1 nm.

[0122] Catalyst Dcat-4 was prepared, and the physicochemical characterization results of catalyst Dcat-4 are shown in Table 3.

[0123] Comparative Example 5

[0124] The method of Example 2 was followed, except that YL-4 was not added in step (1), and the amount of aluminum hydroxide powder YL-3 was 100g. The Al2O3 microsphere carrier DZT-3 was used, and the XRD characterization results of DZT-3 are shown below. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 From this, it can be seen that DZT-3 exhibits a single-peak distribution, with the most probable pore diameter being 3.4 nm.

[0125] Catalyst Dcat-5 was prepared, and the physicochemical characterization results of catalyst Dcat-5 are shown in Table 3.

[0126] Comparative Example 6

[0127] The method of Example 2 was followed, except that YL-3 was not added in step (1), and the amount of aluminum hydroxide powder YL-4 was 100g. The Al2O3 microsphere carrier DZT-4 was used, and the XRD characterization results of DZT-4 are shown below. Figure 1 Its specific surface area and pore volume are shown in Table 2, and the pore distribution is shown in Table 3. Figure 2 From this, it can be seen that DZT-4 exhibits a single-peak distribution, with the most probable pore diameter being 15.6 nm.

[0128] Catalyst Dcat-6 was prepared, and the physicochemical characterization results of catalyst Dcat-6 are shown in Table 3.

[0129] Table 2

[0130]

[0131] Table 3

[0132]

[0133] Test case

[0134] (1) Reactivity test

[0135] The above-mentioned catalysts were loaded into a small fixed-bed reactor, and isobutane with a purity >99.8% by mass was used as the reaction raw material to carry out the isobutane n-assembly reaction. After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion rate and n-butane selectivity were calculated. The specific reaction conditions and results are shown in Table 4.

[0136] in,

[0137] Isobutane conversion rate (%) = ((mass of isobutane in feed - mass of isobutane in product) / mass of isobutane in feed) × 100%;

[0138] n-Butane selectivity (%) = (mass of n-butane in product / (mass of isobutane in feed - mass of isobutane in product)) × 100%.

[0139] Table 4

[0140]

[0141]

[0142] As shown in Table 4, compared with the comparative catalyst, the catalyst of the present invention can achieve both high isobutane conversion and n-butane selectivity, and high n-butane yield.

[0143] (2) Reaction stability test

[0144] Catalysts cat-1 and Dcat-4 were loaded separately into a small fixed-bed reactor. Isobutane with a purity >99.8% by mass was used as the reactant to carry out the isobutane n-assembly reaction. The reaction conditions were: temperature 420℃, pressure 1.0 MPa (gauge pressure), and feed mass hourly space velocity 1.5 h⁻¹. -1 With a hydrogen-to-oil molar ratio of 0.5, the product composition was analyzed using online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The evaluation lasted for 300 hours. The comparative evaluation results of cat-1 and Dcat-4 are as follows: Figure 3 As shown.

[0145] Depend on Figure 3 It can be seen that within the 300-hour evaluation period, the decrease in isobutane conversion rate on the catalyst of the present invention is lower than that of the comparative catalyst, and it always has higher n-butane selectivity, indicating that the catalyst of the present invention has higher stability and a longer single-pass operation cycle.

[0146] 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 combining the 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 normalization catalyst characterized by, The catalyst includes a support and an active metal component and an acidic component supported on the support; The carrier is spherical alumina, which has a bimodal pore distribution of macropores and micropores. The most probable diameter of the micropores is 2-10 nm, and the most probable diameter of the macropores is 11-18 nm. In the spherical alumina, the pore volume of the micropores accounts for 15-70% of the total pore volume, and the pore volume of the macropores accounts for 30-85% of the total pore volume. The active metal component is selected from at least one group VIII metal, and the acidic component is chlorine; Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

2. The catalyst of claim 1, wherein, Based on the weight of the carrier, the content of the active metal component is 0.03-0.5% by weight, and the content of the acidic component is 0.8-1.5% by weight. Preferably, the mass ratio of the active metal component to the acidic component is 1:(3-30) based on elemental composition.

3. The catalyst of claim 1 or 2, wherein, The diameter of the spherical alumina is 1.6-2.2 mm; Preferably, in the spherical alumina, the most probable pore diameter of the small pores is 3-9 nm, and the most probable pore diameter of the large pores is 12-17 nm; Preferably, the pore volume of the spherical alumina is 0.4-0.65 mL / g; Preferably, the specific surface area of ​​the spherical alumina is 170-240 m² / g. 2 / g, preferably 180-230m 2 / g.

4. The catalyst of any one of claims 1-3, wherein, The active metal component is selected from at least one of Fe, Co, Ni, Ru, Rh, Pd and Pt, preferably at least one of Pt, Ru and Pd, and more preferably Pt and / or Pd.

5. A process for the preparation of an isobutane normalization catalyst characterized by, Includes the following steps: (1) Mix the first alumina precursor with a most probable pore diameter of 3-8 nm and the second alumina precursor with a most probable pore diameter of 10-35 nm with a colloid solvent to obtain alumina sol. The mass ratio of the first alumina precursor to the second alumina precursor is 0.1-12:

1. (2) Under stirring conditions, the alumina sol was mixed with the surfactant; (3) The mixture obtained in step (2) is drop-ball shaped, then dried and calcined to obtain a carrier; (4) Loading an active metal component and an acidic component onto the carrier; the active metal component is selected from at least one group VIII metal, and the acidic component is chlorine; Based on the weight of the carrier, the content of the active metal component is 0.01-1% by weight, and the content of the acidic component is 0.5-1.8% by weight.

6. The production method according to claim 5, wherein In step (1), the pore volume of the first alumina precursor is 0.2-0.5 mL / g; Preferably, the pore volume of the second alumina precursor is 0.55-1 mL / g; Preferably, the mass ratio of the first alumina precursor to the second alumina precursor is 0.15-7:1; Preferably, the first alumina precursor and the second alumina precursor are each independently selected from at least one of aluminum hydroxide, boehmite, and gibbsite. Preferably, the adhesive solvent is an aqueous solution of an acid, and the acid is preferably at least one selected from nitric acid, hydrochloric acid, perchloric acid, tartaric acid, lactic acid, citric acid, gluconic acid, formic acid, and acetic acid. Preferably, the concentration of acid in the adhesive solvent is 15-25 wt%. Preferably, the ratio of the mass of acid in the colloidal solvent to the total mass of the first alumina precursor and the second alumina precursor is 0.03-0.15:

1.

7. The production method according to claim 5 or 6, wherein In step (2), the surfactant is a fatty alcohol polyoxyethylene ether, preferably, the chemical structure of the fatty alcohol polyoxyethylene ether is represented as RO-(CH2CH2). n H, where R is a hydrocarbon group, preferably a C10-C20 hydrocarbon group, and n is 7-11; Preferably, the amount of surfactant added is 0.5-2 wt%, based on the total mass of the first alumina precursor and the second alumina precursor.

8. The method of making according to any one of claims 5-7, wherein, The drop ball forming method in step (3) includes: dropping the alumina sol into an oil-ammonia column composed of an oil layer and an ammonia water layer, and curing for 0.5-5 hours; Preferably, the oil phase in the oil layer of the oil-ammonia column is a C10-C14 alkane; Preferably, the mass fraction of ammonia in the ammonia layer of the oil-ammonia column is 4-15 wt%, more preferably 6-12 wt%. Preferably, the thickness of the oil layer in the oil-ammonia column is 2-20 cm, more preferably 4-20 cm; Preferably, the thickness of the ammonia water layer in the oil-ammonia column is 30-150cm, more preferably 50-80cm; Preferably, the roasting temperature in step (3) is 400-700℃ and the roasting time is 0.5-24h.

9. The method of making according to any one of claims 5-8, wherein, In step (4), the method of loading the active metal component and the acid component onto the carrier includes: contacting the carrier with an impregnation solution containing chloride of active metal component, and then drying and calcining. Preferably, the concentration of the impregnation solution containing the chloride of active metal components is 0.1-1.3 wt%, more preferably 0.2-0.8 wt%. Preferably, the mass ratio of the impregnation solution to the carrier is (0.5-2):1, more preferably (0.8-1.2):1; Preferably, the impregnation solution further contains a competitive adsorbent, preferably at least one of hydrochloric acid, trichloroacetic acid, and nitric acid; Preferably, the mass ratio of the amount of the competing adsorbent to the amount of the chloride of the active metal component is (2-25):1, more preferably (4-20):1; Preferably, the contact temperature is 10-70℃ and the contact time is 0.5-10h.

10. The method of making according to any one of claims 5-9, wherein, The preparation method further includes: reducing the product obtained in step (4) in the presence of hydrogen; Preferably, the reduction treatment conditions include: a reduction temperature of 400-600℃, more preferably 450-550℃, a reduction time of 1-10h, more preferably 3-5h, and a gas-agent volume ratio of 300-1500, more preferably 400-1200.

11. A method for isobutane n-assembly, characterized in that, The method includes: contacting an isobutane feedstock with a catalyst in the presence of hydrogen under isobutane normalization reaction conditions; The catalyst is the isobutane normalization catalyst according to any one of claims 1-4 or the isobutane normalization catalyst prepared by the preparation method according to any one of claims 5-10.

12. The method of claim 11, wherein, The isobutane normalization reaction conditions include: a reaction temperature of 380-480℃, preferably 400-470℃; a reaction pressure of 0.5-5 MPa, preferably 0.9-3.5 MPa; a hydrogen / hydrocarbon molar ratio of 0.01-0.9, preferably 0.05-0.8; and a mass hourly space velocity (HHSV) of 0.5-5 h⁻¹ for the isobutane feedstock. -1 Preferably 0.8-4h -1 ; Preferably, the isobutane content in the isobutane raw material is not less than 80% by mass, and more preferably not less than 90%.

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