Isobutane normalizing method

Abstract

The invention relates to the technical field of preparation of n-butane, and discloses an iso-butane normalizing method which comprises the following step: under the iso-butane normalizing reaction condition and in the presence of hydrogen, contacting an iso-butane raw material with a catalyst, the catalyst comprises an alumina carrier, an active metal component and an acidic component, wherein the active metal component and the acidic component are loaded on the alumina carrier; the alumina carrier has bimodal pore distribution of large pores and small pores, the most probable pore diameter of the small pores is 2-10 nm, and the most probable pore diameter of the large pores is 10-20 nm; 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 alumina carrier, 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% in terms of elements. The method has high normalizing activity and high n-butane selectivity.

Description

Technical Field

[0001] This invention relates to the field of n-butane preparation technology, and more specifically to a method for the n-butane n-assembly. Background Technology

[0002] n-Butane is a high-quality feedstock for ethylene cracking. Compared to isobutane, it has higher triene yields and lower methane byproducts. n-Butane is also a feedstock for the oxidative process to produce maleic anhydride. In recent years, many new ethylene cracking units have been built in China. To save energy, reduce consumption, and improve market competitiveness, there is a clear trend towards larger units and lighter feedstocks, leading to a significant shortage of ethylene cracking feedstock. Increasing n-Butane production has become an important option to compensate for this shortage. Since biodegradable plastics mainly use maleic anhydride as a feedstock, the demand for maleic anhydride and its upstream n-butane has surged. n-Butane is mainly found in mixed butane byproducts of petroleum refining processes such as catalytic cracking and hydrocracking. For example, the n-butane content in butane byproducts of catalytic cracking is typically 40%, with the remainder being isobutane. For chemical refineries without alkylation units, isobutane is usually treated as a low-value-added product. Therefore, developing isobutane n-articulation technology to increase the production of urgently needed n-butane is of great significance for improving the economic efficiency of refineries and assisting oil refining enterprises in their transformation towards chemical production.

[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] Therefore, the isobutane normalization reaction disclosed in the prior art has low isobutane normalization activity and n-butane selectivity, resulting in low isobutane normalization efficiency and a large amount of olefins and C1-C3 light components as by-products, which complicates the post-processing. In order to improve the isobutane normalization activity, it is usually necessary to carry out the reaction under conditions of high hydrogen-hydrocarbon molar ratio, which reduces the economic efficiency of normalization technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low isobutane or n-butane selectivity and poor technical economy in the existing isobutane or n- ...

[0007] To achieve the above objectives, 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;

[0008] The catalyst includes an alumina support and an active metal component and an acidic component supported on the alumina support;

[0009] The alumina carrier has a bimodal pore distribution of macropores and micropores, wherein the most probable pore diameter of the micropores is 2-10 nm and the most probable pore diameter of the macropores is 10-20 nm; the active metal component is selected from at least one of group VIII metals, and the acidic component is chlorine;

[0010] Based on the weight of the alumina 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] 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 .

[0012] Through the above technical solution, this invention uses Al2O3 with a bimodal pore distribution as a support to load active metal components and acidic components into a normalization catalyst for isobutane normalization reaction. Under normalization reaction conditions, the active centers in the catalyst can be fully utilized to improve the normalization activity and selectivity of isobutane. The reason for this may be that suitable micropores in the support can increase the density of normalization active centers, while suitable macropores are conducive to the diffusion of reactants and effectively reduce secondary reactions. By selecting an appropriate proportion of Al2O3 with a bimodal pore distribution as a support to load active components and acidic components, the optimal synergy between the catalyst's metal centers and acid centers can be achieved, thereby exhibiting high normalization activity and selectivity in the reaction. Attached Figure Description

[0013] Figure 1These are the XRD patterns of the alumina supports prepared in the preparation examples and comparative preparation examples of this invention;

[0014] Figure 2 This is a pore distribution diagram of the alumina support prepared in the preparation examples and comparative preparation examples of the present invention. Detailed Implementation

[0015] 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.

[0016] The present invention provides a method for isobutane normalization, the method comprising: contacting isobutane feedstock with a catalyst in the presence of hydrogen under isobutane normalization reaction conditions;

[0017] The catalyst includes an alumina support and an active metal component and an acidic component supported on the alumina support;

[0018] The alumina carrier has a bimodal pore distribution of macropores and micropores, wherein the most probable pore diameter of the micropores is 2-10 nm and the most probable pore diameter of the macropores is 10-20 nm; the active metal component is selected from at least one of group VIII metals, and the acidic component is chlorine;

[0019] Based on the weight of the alumina 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.

[0020] The inventors of this invention discovered in their research that by using a support with a suitable distribution of micropores and macropores, and by combining it with active metal components and acidic components, the optimal synergy between the metal centers and acid centers of the catalyst can be achieved. When the above catalyst is used in the isobutane normalization reaction, it can exhibit high normalization activity and selectivity.

[0021] According to some preferred embodiments of the present invention, in the alumina support, the most probable pore diameter of the micropores is 3-9.5 nm, and the most probable pore diameter of the macropores is 10.5-19 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.

[0022] According to the present invention, preferably, the total pore volume of the alumina support is 0.4-0.6 mL / g, more preferably 0.48-0.59 mL / g.

[0023] In a further preferred embodiment, in the alumina support, the pore volume of small pores accounts for 15-65% of the total pore volume, preferably 18-56%; the pore volume of macropores accounts for 35-85% of the total pore volume, preferably 44-82%. Under these preferred conditions, it is beneficial to improve the accessibility of the metal center and acid center, promote the normalization reaction, facilitate the diffusion of reaction products from the active center, reduce secondary reactions, and improve the selectivity of n-butane.

[0024] Preferably, the specific surface area of ​​the alumina carrier is 170-250 m². 2 / g, preferably 190-230m 2 / g.

[0025] In this invention, the specific surface area and pore structure of the alumina 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 area of ​​the catalyst and support was 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.

[0026] In this invention, based on the weight of the alumina 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 alumina support, the content of the active metal component is 0.05-0.5% 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 centers and acid centers, thereby exhibiting higher ortho-configuration activity and selectivity in the reaction.

[0027] According to some preferred embodiments of the present invention, the mass ratio of the active metal component to the acidic component is 1:(3-13), preferably 1:(3.5-11, based on elemental composition.

[0028] In this invention, the active metal element content and Cl content of the catalyst were determined using a Lambda 35 UV-Vis spectrophotometer and a Titrando 905 automatic potentiometric titrator, respectively.

[0029] 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.

[0030] The present invention does not have any particular limitation on the source of the catalyst, which can be prepared by any method known in the art, as long as it meets the above-mentioned pore structure and composition of the support.

[0031] According to some preferred embodiments of the present invention, the method for preparing the catalyst includes:

[0032] (1) A first alumina precursor with a most probable pore diameter of 3-8 nm and a second alumina precursor with a most probable pore diameter of 10-35 nm are mixed and shaped, and then dried and calcined to obtain an alumina carrier.

[0033] (2) The alumina carrier is brought into contact with an impregnation solution containing chlorides containing active metal components, and then dried and calcined.

[0034] The concentration of the impregnation solution containing the chloride with active metal components is 0.1-1.3 wt%.

[0035] (3) The product obtained in step (2) is optionally reduced.

[0036] 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.

[0037] According to the present invention, the most probable pore diameter of the first alumina precursor is 3-8 nm, preferably 4-7 nm. The most probable pore diameter of the second alumina precursor is 10-35 nm, preferably 20-32 nm. Using the above-preferred alumina precursor is beneficial for forming an alumina carrier with a suitable bimodal pore distribution.

[0038] 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.

[0039] Preferably, the pore volume of the second alumina precursor is 0.55-1 mL / g, and more preferably 0.75-0.95 mL / g.

[0040] 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.

[0041] According to some preferred embodiments of the present invention, the mass ratio of the first alumina precursor to the second alumina precursor is 0.1-10:1, for example, it can be a specific but not limiting mass ratio or any range between the two, 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. Preferably, the mass ratio of the first alumina precursor to the second alumina precursor is 0.15-2:1. Using the above-mentioned preferred raw material ratio is beneficial for adjusting the ratio of macropores and micropores in the obtained alumina support, further improving the catalytic activity of the catalyst.

[0042] In this invention, the molding process described in step (1) can be carried out using any conventional method in the art, such as extrusion, granulation, ball rolling, or spray drying into spheres, with extrusion molding being preferred. The shape of the molded body can be any shape, such as strip, sphere, sheet, particle, or microsphere, with strip being preferred, as it is beneficial to improve the reaction effect in the fixed-bed reactor.

[0043] According to the present invention, preferably, the mixing process in step (1) further introduces a peptizing solvent, which can be any conventional choice in the art, and the present invention does not particularly limit it. Preferably, the peptizing solvent is an aqueous solution of an acid, wherein the acid is selected from at least one of nitric acid, acetic acid, citric acid, oxalic acid, and formic acid.

[0044] Preferably, the concentration of the acid in the aqueous solution is 2-10 wt%.

[0045] Preferably, the ratio of the amount of the adhesive solvent to the total mass of the first alumina precursor and the second alumina precursor is 0.3-1:1.

[0046] The present invention does not have any particular requirements for the mixing order in step (1), as long as the components can be mixed evenly. When the adhesive solvent is introduced, preferably, the mixing includes: first mixing the first alumina precursor and the second alumina precursor, and then adding the adhesive solvent.

[0047] According to the present invention, the drying in step (1) can be carried out in a manner and under conditions conventional in the art. Preferably, the drying temperature is 80-140°C and the drying time is 5-30h.

[0048] Preferably, the roasting temperature in step (1) is 500-650℃, more preferably 530-630℃, and the roasting time is 2-24h, more preferably 3-12h.

[0049] According to the present invention, the active metal component and the acidic component chlorine are loaded onto an alumina support in step (2). The present invention does not particularly limit the manner and conditions of contact between the alumina support and the impregnation solution, as long as the above-mentioned loading objective can be achieved.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Preferably, the contact temperature in step (2) is 10-70℃ and the contact time is 0.5-10h.

[0055] Preferably, the drying temperature in step (2) is 80-140℃, more preferably 100-130℃, and the drying time is 5-30h, more preferably 8-24h.

[0056] Preferably, in step (2), the roasting temperature is 450-650℃, more preferably 480-600℃, and the roasting time is 1-10h, more preferably 3-5h.

[0057] According to the present invention, those skilled in the art can perform reduction during the catalyst preparation process or before the reaction, as needed, and the present invention does not have any particular limitations in this regard.

[0058] Preferably, in step (3), the reduction is carried out in the presence of hydrogen, the gas-to-agent volume ratio is 300-1500, preferably 400-1200, the reduction temperature is 400-600℃, preferably 450-550℃, and the reduction time is 1-10h, preferably 3-5h.

[0059] In this invention, an isobutane normalization catalyst supported on Al₂O₃ with a bimodal pore distribution is used to carry out the normalization reaction of isobutane. This catalyst exhibits high isobutane normalization activity and selectivity under relatively low hydrogen-to-hydrogen molar ratio conditions (H / H 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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%.

[0064] The method provided by this invention can be applied to various conventional reactors in the art, such as fixed beds, moving beds, and risers. Those skilled in the art can choose according to actual production needs, with a fixed bed reactor being preferred for the reaction.

[0065] The present invention will be described in detail below through embodiments.

[0066] The following preparation examples illustrate the preparation of ortho-configuration catalysts.

[0067] The aluminum hydroxide powder used in the following preparation examples was purchased from Sasol, and the pore characteristics are shown in Table 1.

[0068] Table 1

[0069] serial number Alumina content (wt%) <![CDATA[BET specific surface area, m 2 / g]]> Pore ​​volume, mL / g Most possible aperture diameter, nm YL-1 75.3 253 0.406 6.3 YL-2 74.6 187 0.821 24.6 YL-3 74.9 306 0.222 4.0 YL-4 72.7 141 0.899 30.5

[0070] Preparation Example 1

[0071] (1) Preparation of Al2O3 support

[0072] 60.0 g of aluminum hydroxide powder YL-1 and 40.0 g of aluminum hydroxide powder YL-2 were mixed evenly. 50.0 g of a 3% (w / w) nitric acid aqueous solution was added to the above powder mixture, and the mixture was stirred and kneaded evenly. The mixture was then extruded into strips, dried at 110℃ for 10 h, and calcined at 560℃ for 4 h to obtain Al2O3 support ZT-1. The XRD characterization results of ZT-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 It can be seen that ZT-1 exhibits a bimodal distribution, with most probable pore diameters of 7.9 nm and 11.5 nm, respectively.

[0073] (2) Preparation of catalyst

[0074] Take 50.0g of 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 at 25℃ for 1h, then evaporate the water in the solution to dryness, dry at 120℃ 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 A. The Pt and Cl content characterization results of catalyst A are shown in Table 3.

[0075] Preparation Example 2

[0076] (1) Preparation of Al2O3 support

[0077] 30.0 g of aluminum hydroxide powder YL-1 and 70.0 g of aluminum hydroxide powder YL-2 were mixed evenly. 100.0 g of a 10% (w / w) nitric acid aqueous solution was added to the above powder mixture, and the mixture was stirred and kneaded evenly. The mixture was then extruded into strips, dried at 110℃ for 10 h, and calcined at 630℃ for 12 h to obtain Al2O3 support ZT-2. 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 8.2 nm and 11.5 nm, respectively.

[0078] (2) Preparation of catalyst

[0079] Take 50.0g of support ZT-2 and add it to 40.0g of an aqueous solution containing 0.125g Pt, chloroplatinic acid, 1% trichloroacetic acid, and 1.8% hydrochloric acid. Soak at 50℃ for 0.5h, then evaporate the water in the solution to dryness, dry at 130℃ for 8h, and then load the dried sample into a tubular reactor for gas treatment. The gas / agent volume ratio during treatment is 1200. The specific steps are as follows: first, purge with nitrogen at 220℃ for 2h, then switch to air and activate at 480℃ for 4h, then replace with nitrogen for 0.5h, and finally reduce with hydrogen at 450℃ for 5h to obtain catalyst B. The Pt and Cl content characterization results of catalyst B are shown in Table 3.

[0080] Preparation Example 3

[0081] (1) Preparation of Al2O3 support

[0082] 50.0 g of aluminum hydroxide powder YL-3 and 50.0 g of aluminum hydroxide powder YL-4 were mixed evenly. 30.0 g of a 5% (w / w) nitric acid aqueous solution was added to the above powder mixture, and the mixture was stirred and kneaded evenly. The mixture was then extruded into strips, dried at 110℃ for 10 h, and calcined at 530℃ for 8 h to obtain Al2O3 support ZT-3. The XRD characterization results of ZT-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 It can be seen that ZT-3 exhibits a bimodal distribution, with most probable pore diameters of 3.7 nm and 15.8 nm, respectively.

[0083] (2) Preparation of catalyst

[0084] Take 50.0g of support ZT-3 and add it to 60.0g of an aqueous solution containing 0.075Pt of chloroplatinic acid and 5% hydrochloric acid by mass. Soak at 15℃ for 10h, then evaporate the water in the solution to dryness, dry at 100℃ for 24h, and then load the dried sample into a tubular reactor for gas treatment. The gas / agent volume ratio during treatment is 400. The specific steps are as follows: first, purge with nitrogen at 220℃ for 2h, then switch to air and activate at 600℃ for 3h, then replace with nitrogen for 0.5h, and finally reduce with hydrogen at 550℃ for 3h to obtain catalyst C. The Pt and Cl content characterization results of catalyst C are shown in Table 3.

[0085] Preparation Example 4

[0086] Following the method of Preparation Example 1, the difference is that in step (2), the amount of chloroplatinic acid in the aqueous solution is 0.06 g Pt, and catalyst D is prepared. The characterization results of the Pt content and Cl content of catalyst D are shown in Table 3.

[0087] Comparative Preparation Example 1

[0088] Following the method of Preparation Example 1, except that chloroplatinic acid was not added during impregnation in step (2), catalyst E was obtained. The characterization results of the Cl content of catalyst E are shown in Table 3.

[0089] Comparative Preparation Example 2

[0090] Take 15.0g of catalyst A prepared in Preparation Example 1, and introduce sublimated AlCl3 vapor into the reactor containing catalyst A using H2 as the carrier gas to chlorinate catalyst A. The amount of AlCl3 used is 2.5g, 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 F. The Pt content and Cl content characterization results of catalyst F are shown in Table 3.

[0091] Comparative preparation example 3

[0092] (1) Preparation of Al2O3 support

[0093] 100.0 g of aluminum hydroxide powder YL-2 was mixed with 50.0 g of 3% (w / w) nitric acid aqueous solution, stirred and kneaded until uniform, extruded into strips, dried at 110℃ for 10 h and calcined at 560℃ for 4 h to obtain Al2O3 support DZT-1. The XRD characterization results of DZT-1 are shown in the figure. 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 ZT-4 exhibits a single-peak distribution, with the most probable pore diameter being 11.5 nm.

[0094] (2) Preparation of catalyst

[0095] Take 50.0g of support DZT-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 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 G. The Pt and Cl content characterization results of catalyst G are shown in Table 3.

[0096] Comparative preparation example 4

[0097] (1) Preparation of Al2O3 support

[0098] 100.0 g of aluminum hydroxide powder YL-1 was mixed with 50.0 g of 3% (w / w) nitric acid aqueous solution, stirred and kneaded until uniform, extruded into strips, dried at 110℃ for 10 h, and calcined at 560℃ for 4 h to obtain Al2O3 support DZT-2. 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 9.7 nm.

[0099] (2) Preparation of catalyst

[0100] Take 50.0g of support DZT-2 and add it to 55.0g of an aqueous solution containing 0.125g Pt, 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 H. The Pt and Cl content characterization results of catalyst H are shown in Table 3.

[0101] Comparative preparation example 5

[0102] (1) Preparation of Al2O3 support

[0103] 100.0 g of aluminum hydroxide powder YL-3 was mixed with 50.0 g of 3% (w / w) nitric acid aqueous solution, stirred and kneaded until uniform, extruded into strips, dried at 110℃ for 10 h, and calcined at 560℃ for 4 h to obtain Al2O3 support DZT-3. 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.

[0104] (2) Preparation of catalyst

[0105] Take 50.0g of support DZT-3 and add it to 55.0g of an aqueous solution containing 0.125g Pt, 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 I. The Pt and Cl content characterization results of catalyst I are shown in Table 3.

[0106] Comparative preparation example 6

[0107] (1) Preparation of Al2O3 support

[0108] 100.0 g of aluminum hydroxide powder YL-4 was mixed with 50.0 g of 3% (w / w) nitric acid aqueous solution, stirred and kneaded until uniform, extruded into strips, dried at 110℃ for 10 h, and calcined at 560℃ for 4 h to obtain Al2O3 support DZT-4. 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.

[0109] (2) Preparation of catalyst

[0110] Take 50.0g of support DZT-4 and add it to 55.0g of an aqueous solution containing 0.125g Pt, 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 J. The Pt and Cl content characterization results of catalyst J are shown in Table 3.

[0111] Table 2

[0112]

[0113] Table 3

[0114]

[0115]

[0116] The following examples illustrate the isobutane ortho-configuration method of the present invention.

[0117] Example 1

[0118] A small fixed-bed reactor was loaded with catalyst A and isobutane with a purity >99.8% by mass was used as the reactant to carry out the isobutane n-assembly reaction. The reaction temperature was 450℃, the reaction pressure was 3MPa, and the feed space velocity of the reactant was 1.5h⁻¹. -1 The molar ratio of hydrogen to isobutane feedstock is 0.5.

[0119] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0120] in,

[0121] Isobutane conversion rate (%) = ((mass of isobutane in feed - mass of isobutane in product) / mass of isobutane in feed) × 100%;

[0122] n-Butane selectivity (%) = (mass of n-butane in product / (mass of isobutane in feed - mass of isobutane in product)) × 100%.

[0123] Examples 2-4

[0124] The method of Example 1 was followed, except that catalyst A was replaced with the catalysts prepared in Examples 2-4. The reaction conditions are shown in Table 4.

[0125] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0126] Example 5

[0127] The method is the same as in Example 1, except that the hydrogen-to-oil molar ratio is 1.

[0128] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0129] Example 6

[0130] The method is the same as in Example 1, except that the reaction temperature is 500°C.

[0131] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0132] Comparative Example 1

[0133] The method of Example 1 was followed, except that catalyst A was replaced with the catalyst prepared in Comparative Preparation Example 1.

[0134] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0135] Comparative Example 2

[0136] The method of Example 5 was followed, except that catalyst A was replaced with the catalyst prepared in Comparative Preparation Example 2.

[0137] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0138] Comparative Examples 3-6

[0139] The method of Example 1 was followed, except that catalyst A was replaced with the catalysts prepared in Comparative Preparation Examples 3-6.

[0140] After 12 hours of reaction, the product composition was analyzed by online gas chromatography, and the isobutane conversion and n-butane selectivity were calculated. The results are shown in Table 4.

[0141] Table 4

[0142]

[0143] As can be seen from the results in Table 4, the isobutane normalization method provided by this invention uses Al2O3 with a bimodal pore distribution as a support to load active metal components and acidic components as a normalization catalyst, which can improve the activity and selectivity of isobutane normalization under low hydrogen-oil molar ratio conditions.

[0144] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the n-assembly of isobutane, 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 includes an alumina support and an active metal component and an acidic component supported on the alumina support; The alumina carrier has a bimodal pore distribution of macropores and micropores, wherein the most probable pore diameter of the micropores is 2-10 nm and the most probable pore diameter of the macropores is 10-20 nm; the active metal component is selected from at least one of group VIII metals, and the acidic component is chlorine; Based on the weight of the alumina 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 method according to claim 1, wherein, In the alumina carrier, the most probable pore diameter of the micropores is 3-9.5 nm, and the most probable pore diameter of the macropores is 10.5-19 nm.

3. The method according to claim 1 or 2, wherein, The total pore volume of the alumina support is 0.4-0.6 mL / g, preferably 0.48-0.59 mL / g; Preferably, the specific surface area of the alumina support is comprised between 170 and 250 m 2 / g, preferably between 190 and 230 m 2 / g; Preferably, in the alumina carrier, the pore volume of small pores accounts for 15-65% of the total pore volume, and the pore volume of large pores accounts for 35-85% of the total pore volume.

4. The method according to any one of claims 1-3, wherein, Based on the weight of the alumina carrier, the content of the active metal component is 0.05-0.5% 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:(3-13) based on elemental composition.

5. The method according to any one of claims 1-4, 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.

6. The method according to any one of claims 1-5, wherein, The method for preparing the catalyst includes: (1) A first alumina precursor with a most probable pore diameter of 3-8 nm and a second alumina precursor with a most probable pore diameter of 10-35 nm are mixed and shaped, and then dried and calcined to obtain an alumina carrier. (2) The alumina carrier is brought into contact with an impregnation solution containing chlorides containing active metal components, and then dried and calcined. The concentration of the impregnation solution containing the chloride with active metal components is 0.1-1.3 wt%. (3) The product obtained in step (2) is optionally reduced.

7. The method according to claim 6, 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 0.1-10:1, more preferably 0.15-2:1; Preferably, the first alumina precursor and the second alumina precursor are each independently selected from at least one of aluminum hydroxide, boehmite, and gibbsite.

8. The method according to claim 6 or 7, wherein, The concentration of the chloride impregnation solution containing the active metal component is 0.2-0.8 wt%. Preferably, the mass ratio of the impregnation solution to the alumina carrier is (0.5-2):1, more preferably (0.8-1.2):1; Preferably, the impregnation solution also contains a competitive adsorbent, preferably at least one of hydrochloric acid, trichloroacetic acid, and nitric acid.

9. The method according to any one of claims 6-8, wherein, In step (2), the roasting temperature is 450-650℃, preferably 480-600℃, and the roasting time is 1-10h, preferably 3-5h; Preferably, in step (3), the reduction is carried out in the presence of hydrogen, the gas-to-agent volume ratio is 300-1500, the reduction temperature is 400-600℃, and the reduction time is 1-10h.

10. The method according to any one of claims 1-9, wherein, The isobutane normalization reaction conditions include: reaction temperature of 380-480°C, preferably 400-470°C, reaction pressure of 0.5-5 MPa, preferably 0.9-3.5 MPa, hydrogen / hydrocarbon molar ratio of 0.01-0.9, preferably 0.05-0.8; mass space velocity of isobutane raw material of 0.5-5 h -1 , preferably 0.8-4 h -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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