Isobutane normalizing method and isobutane normalizing reaction system

Abstract

The invention relates to the technical field of iso-butane normalizing, and discloses an iso-butane normalizing method and an iso-butane normalizing reaction system.The iso-butane normalizing method comprises the step that under the hydrogen condition and the iso-butane normalizing reaction condition, an iso-butane raw material makes contact with a catalyst, wherein the catalyst comprises an acidic active component SO4 < 2-> / ZrO2, an all-silicon molecular sieve with an MFI structure and aluminum oxide; the density of the strong acid center in the catalyst is 0.1-2 [mu] mol / m < 2 >. The method has the advantages of high isobutane conversion per pass, high n-butane selectivity and high n-butane yield.

Description

Technical Field

[0001] The invention relates to the technical field of isobutane normalization, and in particular to an isobutane normalization method and an isobutane normalization reaction system. Background Art

[0002] n-Butane is a high-quality raw material for ethylene cracking. Compared with isobutane, it has the characteristics of high triene yield and less by-product methane. n-Butane is also the raw material for the oxidation process of maleic anhydride. In recent years, many sets of ethylene cracking units have been newly built in China. In order to save energy and reduce consumption and improve market competitiveness, the trend of large-scale units and lightweight raw materials is obvious, which has caused a large gap in ethylene cracking raw materials. Increasing the production of n-butane has become an important option to make up for the shortage of ethylene cracking raw materials. In addition, the market for fully biodegradable plastics has ushered in unprecedented development opportunities. Since biodegradable plastics are mainly made of maleic anhydride as raw materials, the demand for maleic anhydride and its upstream n-butane has surged. In my country, n-butane mainly exists in mixed butanes produced as by-products of petroleum refining processes such as catalytic cracking and hydrocracking. For example, the n-butane content in catalytic cracking by-product butane is usually 40%, and the rest is isobutane. For chemical refineries without alkylation units, isobutane is usually treated as a low value-added product. Therefore, developing isobutane normalization technology and increasing the production of normal butane that is urgently needed in the market are of great significance for improving the economic benefits of refineries and helping oil refining companies transform into chemical companies.

[0003] Normalization of isobutane is an acid-catalyzed reaction. The normalization methods of isobutane disclosed in the prior art use normalization catalysts with two main types of acid centers: one is chloride and the other is SO4 2- / ZrO2. CN104892339A discloses a method for preparing normal butane from isobutane, wherein isobutane-rich carbon four hydrocarbons are fed into a normalization reaction zone, isobutane is converted into normal butane under the action of a catalyst, and then the reaction product is fed into a hydrogenation saturation zone for hydrogenation reaction, the olefins in the reaction product are hydrogenated and saturated, and the hydrogenated logistics is fed into a separation unit to be separated into normal butane products, light components and isobutane, and the isobutane is recycled back to the normalization zone for reaction. The normalization reaction temperature described in the invention is 200-700°C, the operating pressure is 2-5MPa, the molar ratio of the total hydrogen content to the isobutane in the feed is 1-3:1, and the catalyst used comprises a carrier, an active component and an acidic component, the active component is composed of one or more transition group VIII elements, and the acidic component is a chloride. CN110385142A discloses a catalyst for normalization reaction of isobutane and a preparation method thereof. The catalyst uses MCM-41 molecular sieve as carrier and Pt / SO4 2- / ZrO2 is the active component, and the temperature for the normalization reaction of isobutane is 150-350℃, the pressure is 1.5-4.5MPa, and the mass space velocity of isobutane is 0.5-3.0h -1The volume ratio of hydrogen to isobutane feed is 200: 1. The yield of n-butane in this method is less than 22.1%.

[0004] It can be seen that in the prior art, when the isobutane normalization catalyst uses chloride as the acid center, the normalization reaction temperature is high, the dehydrogenation side reaction is difficult to avoid, the reaction product contains more olefins, and a hydrogenation saturation unit is required to hydrogenate and saturate the olefins in the reaction product, the process flow is complicated, and the energy consumption is high. 2- When / ZrO2 is the acid center, although the normalization reaction temperature is reduced, the single-pass conversion rate of the reaction is low, and the yield of n-butane is low. It is necessary to separate a large amount of unconverted isobutane in the product, and the separation energy consumption is high. In addition, the reaction hydrogen-hydrocarbon ratio is relatively high. In actual application, it is necessary to separate hydrogen from the reaction product and circulate it using a circulating hydrogen compressor, which further increases energy consumption and operating costs. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of low isobutane conversion rate and low n-butane yield in the isobutane normalization reaction in the prior art, and to provide an isobutane normalization method and an isobutane normalization reaction system. The method has high isobutane single-pass conversion rate and n-butane selectivity, and high n-butane yield.

[0006] In order to achieve the above object, the present invention provides a method for normalization of isobutane, which comprises: contacting an isobutane raw material with a catalyst under hydrogen conditions and under isobutane normalization reaction conditions;

[0007] Wherein, the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 .

[0008] Preferably, the normalization reaction conditions of isobutane include: reaction temperature of 170-250°C, preferably 180-230°C; pressure of 0.5-3.5MPa, preferably 1-3MPa; mass space velocity of isobutane raw material of 0.5-10h -1 , preferably 1-5h -1 , more preferably 1.2-4h -1 ; The hydrogen / hydrocarbon molar ratio is 0.02-0.3, preferably 0.03-0.2.

[0009] Another aspect of the present invention provides an isobutane normalization reaction system, the reaction system comprising: a feed unit, a preheating device, a reactor 4, a light component separation device 5 and a deisobutanizer 6;

[0010] The feed unit is connected to the feed port of the preheating device to feed the isobutane raw material and hydrogen into the preheating device for preheating;

[0011] The outlet of the preheating device is connected to the feed port of the reactor 4, and the preheated raw materials are fed into the reactor 4 to contact with the catalyst; the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 ;

[0012] The light component separation device 5 is used to separate the reaction products from the reactor 4, recover the obtained light components, and send the obtained heavy components to the deisobutanizer 6; wherein the light components include C1-C3 hydrocarbons and H2, and the heavy components include C4 + hydrocarbon;

[0013] The deisobutanizer 6 is used to separate isobutane and normal butane products, and the separated isobutane is returned to the feed unit.

[0014] The catalyst used in the isobutane normalization method provided by the present invention includes an acidic active component SO4 2- / ZrO2, an all-silicon molecular sieve with an MFI structure, and alumina, the acid center of the catalyst is modulated by the all-silicon molecular sieve with an MFI structure, and the distribution of the acid center of the catalyst is optimized without changing the active phase structure and acid strength of the catalyst. The catalyst is used for the normalization reaction of isobutane, which has a high isobutane single-pass conversion rate and n-butane selectivity. Isobutane can be used to increase the production of n-butane, and high-quality raw materials are provided for ethylene cracking devices and butane oxidation-based maleic anhydride devices, thereby realizing the value-added utilization of butane resources. Preferably, the isobutane normalization reaction method provided by the present invention can efficiently convert isobutane into n-butane under the reaction conditions of lower temperature, lower hydrogen-to-oil ratio and higher space velocity, greatly reducing the amount of hydrogen used, which can reduce energy consumption and raw material costs, and is conducive to reducing the difficulty of post-processing and separation, and has good reaction economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The XRD spectra of the all-silicon MFI molecular sieve (Si-1), ZSM-5 molecular sieve (Si-2) and MCM-41 (Si-3) used in the preparation examples of the present invention;

[0016] Figure 2 is the XRD spectra of the catalysts prepared in Preparation Examples 1-3 of the present invention and Comparative Preparation Example 1;

[0017] Figure 3 It is a schematic diagram of an isobutane normalization reaction system in one embodiment of the present invention.

[0018] Description of Reference Numerals

[0019] 1 Feed pump 2 Heat exchanger 3 Heater

[0020] 4 Reactor 5 Light component separation unit 6 Deisobutanizer DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] The present invention provides a method for normalization of isobutane, which comprises: contacting an isobutane raw material with a catalyst under hydrogen conditions and under isobutane normalization reaction conditions;

[0023] Wherein, the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 .

[0024] According to the present invention, the catalyst used in the method for normalization of isobutane contains an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina have suitable strong acid center density. However, the density of strong acid center in super strong solid acid sulfate zirconium oxide in the prior art is relatively high, generally higher than 2μmol / m 2 . The inventors of the present invention have found in their research that a small amount of all-silicon molecular sieves and alumina with an MFI structure can play a role in adjusting the distribution of strong acid centers of solid acid catalysts, thereby making the catalyst highly active and highly selective. The reason for this is that, on the one hand, since the all-silicon molecular sieve with an MFI structure has basically no acidity and excellent thermal stability, it can avoid the introduction of new acid centers and optimize the distribution of strong acid centers in zirconium sulfate oxide, which is beneficial to the efficient activation and conversion of butane molecules through a single molecule pathway. On the other hand, the special pore structure of the all-silicon molecular sieve with an MFI structure is beneficial to the diffusion of reactants and products, thereby effectively avoiding the occurrence of secondary reactions.

[0025] In the solid acid catalyst system in the prior art, molecular sieves are usually used as carriers, and the molecular sieves used as carriers occupy a relatively high content in the catalyst; at the same time, the silicon-aluminum molecular sieve introduced into the catalyst is also usually used to provide additional acidic active centers.

[0026] Preferably, in the catalyst, the density of the strong acid center is 0.5-1.5 μmol / m 2 , for example, 0.5 μmol / m 2 , 0.6μmol / m 2 , 0.7 μmol / m 2 , 0.8 μmol / m 2 , 0.9 μmol / m 2 , 1μmol / m 2 , 1.1 μmol / m 2 , 1.2 μmol / m 2 , 1.3 μmol / m 2 , 1.4 μmol / m 2 , 1.5 μmol / m 2 The above preferred range is conducive to further improving the isobutane conversion rate and n-butane selectivity of the isobutane normalization reaction and improving the n-butane yield.

[0027] In the present invention, the density of the strong acid center is the ratio of the amount of strong acid in the catalyst to the specific surface area. The method for testing the amount of strong acid in the catalyst includes: using a Nicolet 6700 Fourier transform infrared spectrometer produced by Thermo Fisher, USA, with a resolution of 4 cm -1 , scanned 64 times. The sample was pressed into a self-supporting sheet with a diameter of 13 mm, and then placed in a muffle furnace for high-temperature calcination. After completion, it was directly transferred to a dryer for cooling at high temperature. After cooling to room temperature, it was placed in a homemade quartz infrared sample cell, first treated at 400°C for 2 hours under normal pressure flowing air, then cooled to 200°C, vacuum purified for 4 hours, and then cooled to -190°C with liquid nitrogen. The purified CO probe molecules were saturated and adsorbed for 0.5 hours before desorption. The spectra before and after adsorption were subtracted to obtain the infrared spectrum of the sample adsorbed CO. For the wave number of 2050-2250cm -1 The spectrum at 2186cm is processed by peak separation. The spectrum can be divided into four absorption peaks with wave numbers of 2186cm -1 、2167cm -1 、2150cm -1 and 2125cm -1 , where the wave number is 2167cm -1 The absorption peak at is the strong acid center directly related to the catalyst performance. The strong acid amount N (in μmol / g) is calculated according to formula (1): N = A / (ρA0). Formula (1):

[0028] Where A is the integrated area of ​​the absorption peak (in cm -1), ρ is the mass of the catalyst support per square centimeter (in g / cm 2 ), A0 is the molar extinction coefficient, for a wave number of 2167 cm -1 The spectral peak is A0=2.6cm / μmol.

[0029] In the present invention, the catalyst specific surface area is characterized by low temperature nitrogen static volume adsorption method (BET method), the instrument used is ASAP2400 specific surface measuring instrument produced by Micromeritics Instrument Company, the pretreatment conditions are: 250 ° C, 1.3 Pa, treatment for 4 hours, and the specific surface area (m 2 / g).

[0030] In the present invention, the phase analysis of the catalyst sample is carried out using a Japanese Rigaku D / MAX-3A diffractometer (XRD), and the analysis conditions are: ray source CuKα target, Ni filter, scanning range 5°-70°, step width 0.02°.

[0031] Preferably, the isobutane normalization reaction method provided by the present invention can efficiently convert isobutane into normal butane under the reaction conditions of lower temperature, lower hydrogen-to-oil ratio and higher space velocity. Preferably, the isobutane normalization reaction conditions include: reaction temperature of 170-250°C, preferably 180-230°C; pressure of 0.5-3.5MPa, preferably 1-3MPa; mass space velocity of isobutane raw material of 0.5-10h -1 , preferably 1-5h -1 ; The hydrogen / hydrocarbon molar ratio is 0.02-0.3, preferably 0.03-0.2. The above preferred embodiment is conducive to significantly reducing the amount of hydrogen used, which can not only reduce energy consumption and raw material costs, but also reduce the difficulty of post-processing and separation, and the reaction economy is good. 2- When the isobutane normalization reaction is carried out using / ZrO2 as the acid center catalyst, the hydrogen-to-hydrocarbon molar ratio is usually not less than 1.

[0032] According to some preferred embodiments of the present invention, in the catalyst, the mass ratio of the acidic active component in terms of ZrO2 to the mass ratio of the all-silicon molecular sieve in terms of SiO2 is 1:(0.1-1), for example, it can be 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, etc., which are typical but non-limiting mass ratios or ranges therebetween. Preferably, in the catalyst, the mass ratio of the acidic active component in terms of ZrO2 to the mass ratio of the all-silicon molecular sieve in terms of SiO2 is 1:(0.15-0.5). Under the above preferred mass ratio conditions, it is beneficial for the catalyst to have a suitable strong acid center density.

[0033] According to some preferred embodiments of the present invention, the catalyst comprises zirconium, silicon, aluminum and sulfur, and the content of zirconium oxide, silicon oxide, aluminum oxide and SO3 is respectively calculated based on the total mass of the catalyst, and the content of zirconium oxide is 30-90wt%, the content of silicon oxide is 1-35wt%, the content of aluminum oxide is 5-50wt%, and the content of SO3 is 1-10wt%; preferably, based on the total mass of the catalyst, the content of zirconium oxide is 50-80wt%, the content of silicon oxide is 5-30wt%, the content of aluminum oxide is 5-30wt%, and the content of SO3 is 2-8wt%. Under the above preferred composition, it is beneficial to improve the thermal stability of tetragonal zirconium oxide and the specific surface area of ​​the catalyst, so that the catalyst has a suitable distribution of strong acid centers and accessibility of active centers, and further improves the conversion rate of isobutane and the selectivity of n-butane.

[0034] Preferably, the mass ratio of SO3 to ZrO2 is (0.02-0.12):1, preferably (0.03-0.08):1.

[0035] In the present invention, the catalyst composition is characterized and analyzed using an XRF-1800 wavelength dispersive X-ray fluorescence spectrometer, and the content of each element in the sample is obtained through theoretical calculation and mathematical correction based on the intensity of the elements present in the sample obtained by scanning and the pure substance sensitivity of these elements in the instrument.

[0036] According to the present invention, the specific surface area of ​​the catalyst is 80-180m 2 / g, preferably 90-160m 2 / g, more preferably 100-150m 2 / g.

[0037] According to some preferred embodiments of the present invention, the aluminum oxide is γ-Al2O3. In the above preferred case, it is beneficial to improve the thermal stability and specific surface area of ​​the catalyst.

[0038] In the present invention, there is no particular limitation on the shape of the catalyst, and those skilled in the art can select it according to actual needs. For example, it can be in the form of strips, pellets, sheets, particles or microspheres, suitable for fixed bed, moving bed or fluidized bed reactions.

[0039] According to some preferred embodiments of the present invention, the method for preparing the catalyst comprises:

[0040] (1) mixing an all-silicon molecular sieve having an MFI structure and zirconium hydroxide to obtain a mixture;

[0041] Wherein, the mass ratio of the zirconium hydroxide calculated by the mass of ZrO2 to the all-silicon molecular sieve calculated by the mass of SiO2 is 1:(0.1-1);

[0042] (2) contacting the mixture with a solution containing sulfate;

[0043] (3) The product obtained in step (2), an alumina precursor and an optional peptizing agent are mixed, and then molded and calcined.

[0044] According to the present invention, the above-mentioned preparation method can make the all-silicon molecular sieve with MFI structure evenly distributed in the catalyst without blocking the catalyst pores, and the density of the strong acid center in the sulfated zirconium oxide is reduced without introducing new acid centers. The presence of strong acid sites with suitable density and uniform strength is conducive to the efficient activation and conversion of butane molecules through a single molecule path, so that the catalyst simultaneously exhibits high activity and high selectivity in the butane isomerization reaction.

[0045] The present invention has a wide selection range for the number of pores and the pore structure of the all-silicon molecular sieve, and any all-silicon molecular sieve with an MFI structure can be applied to the present invention.

[0046] In some preferred embodiments, the specific surface area of ​​the all-silicon molecular sieve is 400-500m 2 / g, preferably 420-460m 2 In the above preferred case, it is beneficial to further optimize the density of the strong acid center in the sulfated zirconium oxide, improve the uniformity of the strong acid site, and thus improve the normal isomerization activity.

[0047] According to some preferred embodiments of the present invention, the mass ratio of the zirconium hydroxide calculated by the mass of ZrO2 to the all-silicon molecular sieve calculated by the mass of SiO2 is 1:(0.15-0.5).

[0048] In the present invention, the acidic active component is formed by contacting the mixture with a solution containing sulfate in step (2). The contact can be carried out in a conventional manner in the art, for example, the mixture can be impregnated with a solution containing sulfate.

[0049] The present invention has no particular limitation on the specific operating conditions of the contact, as long as the catalyst composition range described above is met, and those skilled in the art can make the selection according to actual needs.

[0050] According to some preferred embodiments of the present invention, the contacting temperature is 20-80°C, preferably 25-60°C; and the contacting time is 1-10h, preferably 2-5h.

[0051] The present invention has a wide range of selection for the specific type of the solution containing sulfate radicals. Preferably, the solution containing sulfate radicals is selected from an aqueous solution of at least one of sulfuric acid, ammonium sulfate and ammonium bisulfate.

[0052] Preferably, the concentration of sulfate in the solution containing sulfate is 1-10wt%, preferably 2-8wt%. The above preferred embodiment is conducive to obtaining a suitable SO3 content and strong acid center density.

[0053] The present invention has no particular limitation on the amount of the solution containing sulfate, as long as it meets the requirements of the SO3 content range in the catalyst described in the first aspect, and those skilled in the art can select it according to actual needs. Preferably, the mass ratio of the solution containing sulfate to the mixture is 0.3-5:1, preferably 0.5-3:1.

[0054] In the present invention, after the contacting in step (2), an optional drying and grinding step is further included. The drying temperature may be 50-150° C., and the drying time may be 3-100 hours. The grinding is used to grind the dried solid into a powder of 100-300 meshes, which is beneficial to improve the crushing strength of the catalyst in the above preferred case.

[0055] In the present invention, the alumina precursor refers to a substance that can obtain alumina by calcination, which is well known to those skilled in the art. Preferably, the alumina precursor is pseudo-boehmite and / or gibbsite, preferably pseudo-boehmite. In the above preferred case, it is beneficial to improve the thermal stability and crushing strength of the catalyst.

[0056] In the present invention, the molding in step (3) can be carried out by conventional methods and conditions in the art, and the present invention has no particular limitation thereto. The molding method can be selected according to the actual application needs, for example, it can be selected from any one of extrusion molding, granulation molding, ball rolling molding and spray drying spheronization, preferably extrusion molding. In the above preferred case, it is more suitable for a fixed bed reactor.

[0057] According to some preferred embodiments of the present invention, the total mass ratio of the peptizing agent to the product obtained in step (2) to the alumina precursor is 0.3-1:1, preferably 0.4-0.8:1.

[0058] According to some preferred embodiments of the present invention, the peptizing agent is an aqueous solution of an acid, preferably an aqueous solution of at least one selected from nitric acid, acetic acid, citric acid, oxalic acid and formic acid.

[0059] Preferably, the concentration of the acid in the peptizing agent is 2-10 wt %.

[0060] According to some preferred embodiments of the present invention, in step (3), the calcination temperature is 600-850° C., preferably 650-850° C., and the calcination time is 1-20 hours, preferably 3-12 hours. Under the above preferred calcination temperature conditions, it is beneficial to form a strong acid center with a suitable density, which is beneficial to improve the activity and selectivity of the catalyst in the butane isomerization reaction.

[0061] In the present invention, step (3) may further include a drying process before the calcination. Preferably, the drying temperature is 80-140° C., preferably 100-130° C., and the drying time is 5-30 hours, preferably 8-24 hours.

[0062] According to the present invention, there is no particular requirement for the source of the isobutane raw material, and it may include isobutane and optional impurity components. Preferably, the content of isobutane in the isobutane raw material is not less than 80wt%, preferably not less than 90wt%, and more preferably 95-100wt%. In the case of the above preferred isobutane content, it is beneficial to improve the yield of normal butane.

[0063] Preferably, the impurity component is selected from at least one of C1-C3 alkanes, n-butane, C5+ alkanes, water and sulfur.

[0064] Preferably, the content of C1-C3 alkanes in the isobutane raw material is less than 1 wt%, preferably less than 0.5 wt%.

[0065] Preferably, the content of C5+ alkanes in the isobutane raw material is less than 1.5 wt%, preferably less than 1 wt%.

[0066] Preferably, the content of n-butane in the isobutane raw material is less than 2wt%, preferably less than 1wt%. In the present invention, the content of hydrocarbons in the isobutane raw material is obtained by gas chromatography test and then normalized to obtain the content of each component.

[0067] Preferably, the water content in the isobutane feedstock is less than 5 ppmw, preferably less than 3 ppmw.

[0068] Preferably, the sulfur content in the isobutane raw material is less than 10 ppmw, preferably less than 5 ppmw.

[0069] According to some preferred embodiments of the present invention, the method further comprises: preheating the isobutane raw material and hydrogen to the isobutane normalization reaction temperature, and then contacting with the catalyst. According to the present invention, the isobutane raw material and hydrogen can be preheated separately, or the isobutane raw material and hydrogen can be mixed and then preheated together. From the perspective of economy, it is preferred to mix the isobutane raw material and hydrogen and then preheat them together.

[0070] Preferably, the preheating includes primary preheating and secondary preheating, and the primary preheating includes: exchanging heat between the product of the normalization reaction of isobutane and the isobutane raw material and / or hydrogen. The primary preheating can be performed using a conventional heat exchange device in the art, such as a shell and tube heat exchanger. The secondary preheating can be performed using a gas heating furnace, an electric heater or a medium-pressure steam heater. Those skilled in the art can select the temperature of the secondary preheating according to the actual operating conditions, as long as the raw material after the primary preheating can be heated to the reaction temperature.

[0071] It is understandable that, when the reaction is initially started, the raw material can be directly heated to the isobutane normalization reaction temperature by secondary preheating. When the reaction is continuously running, the isobutane raw material and / or hydrogen are heat exchanged with the product of the isobutane normalization reaction by primary preheating, and then further heated to the isobutane normalization reaction temperature by secondary preheating. The above preferred embodiment is conducive to further reducing the reaction energy consumption and improving the economy of the isobutane normalization process.

[0072] According to the present invention, preferably, the method further comprises: separating and purifying the contacted product. The separation and purification can be carried out in any manner known in the art, as long as n-butane can be separated from the product. Preferably, the separation and purification comprises: separating the contacted product by distillation to obtain a light component and a heavy component, wherein the light component comprises C1-C3 hydrocarbons and H2, and the heavy component comprises C4 + and then separating isobutane from the heavy component through a deisobutanizer, and the separated isobutane can be reused as an isobutane raw material.

[0073] The second aspect of the present invention provides an isobutane normalization reaction system, the reaction system comprising: a feed unit, a preheating device, a reactor 4, a light component separation device 5 and a deisobutanizer 6;

[0074] The feed unit is connected to the feed port of the preheating device to feed the isobutane raw material and hydrogen into the preheating device for preheating;

[0075] The outlet of the preheating device is connected to the feed port of the reactor 4, and the preheated raw materials are fed into the reactor 4 to contact with the catalyst; the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 ;

[0076] The light component separation device 5 is used to separate the reaction products from the reactor 4, recover the obtained light components, and send the obtained heavy components to the deisobutanizer 6; wherein the light components include C1-C3 hydrocarbons and H2, and the heavy components include C4 + hydrocarbon;

[0077] The deisobutanizer 6 is used to separate isobutane and normal butane products, and the separated isobutane is returned to the feed unit.

[0078] The catalyst in the isobutane normalization reaction system of the present invention has the same definition as the catalyst described in the first aspect, which will not be repeated here.

[0079] According to some preferred embodiments of the present invention, the feeding unit includes an isobutane raw material supply device and a hydrogen supply device.

[0080] Preferably, the isobutane raw material supply device comprises a feed pump 1, and the isobutane raw material is transported to the preheating device through the feed pump 1 for preheating.

[0081] Preferably, the preheating device comprises a heat exchanger 2 and a heater 3.

[0082] The heat exchanger 2 is used to exchange heat between the reaction product from the reactor 4 and the isobutane raw material and hydrogen from the feed unit. The reaction product after heat exchange is sent to the light component separation device 5, and the isobutane raw material and hydrogen are sent to the heater 3;

[0083] The heater 3 is used to heat the isobutane raw material and hydrogen from the heat exchanger 2 to the isobutane normalization reaction temperature, and then send them into the reactor 4.

[0084] The present invention will be described in detail below through examples.

[0085] The bulk structure of the molecular sieve and the catalyst was analyzed and detected by using a Japanese Rigaku D / MAX-3A diffractometer (XRD). The analysis conditions were: radiation source CuKα target, Ni filter, scanning range 5°-70°, step width 0.02°.

[0086] The composition of molecular sieve and catalyst was characterized and analyzed by XRF-1800 wavelength dispersive X-ray fluorescence spectrometer. The content of each element in the sample was obtained through theoretical calculation and mathematical correction based on the intensity of the elements present in the sample obtained by scanning and the sensitivity of the pure substances of these elements in the instrument.

[0087] The zirconium hydroxide powder used was purchased from Changling Catalyst Company, and the zirconium oxide content was 78.5% by weight.

[0088] The all-silicon MFI molecular sieve Si-1 used was purchased from Changling Catalyst Company, with a silicon oxide content of 99.7% by mass and a specific surface area of ​​444.6 m 2 / g, XRD characterization Figure 1 shown.

[0089] Pseudo-boehmite powder was purchased from Sasol, Germany, with an alumina content of 75% by mass.

[0090] The following preparation examples are used to illustrate the preparation of the catalyst in the present invention.

[0091] Preparation Example 1

[0092] Take 38.2g of zirconium hydroxide powder and 4.4g of all-silicon MFI molecular sieve Si-1 and mix them evenly, add 48.0g of 5% by mass sulfuric acid aqueous solution, soak at 40°C for 4h, and dry the impregnated solid at 60°C for 12h and 120°C for 12h.

[0093] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and mixed evenly with 14.4 g of pseudo-boehmite powder. A nitric acid aqueous solution with a concentration of 5.0 mass % was added for peptization. The ratio of the total mass of the nitric acid aqueous solution to the fine powder and the alumina precursor was 0.6:1. After kneading evenly, the wet strips were extruded into strips. The wet strips were dried at 120°C for 10 hours and calcined at 680°C for 4 hours to obtain catalyst A1. The XRD characterization results of catalyst A1 are shown in Figure 2 ,Depend on Figure 2 The characteristic peaks of all-silicon MFI molecular sieve can be seen; the composition and physicochemical properties of the catalyst are shown in Table 1 and Table 1.

[0094] Preparation Example 2

[0095] Take 38.2g of zirconium hydroxide powder and 7.8g of all-silicon MFI molecular sieve, mix them evenly, add 48.0g of 5% by mass sulfuric acid aqueous solution, soak at 40°C for 4h, and dry the soaked solid at 60°C for 12h and 120°C for 12h.

[0096] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and mixed evenly with 10.6 g of pseudo-boehmite powder. A nitric acid aqueous solution with a concentration of 5.0 mass % was added for peptization. The ratio of the total mass of the nitric acid aqueous solution to the fine powder and the alumina precursor was 0.5:1. After kneading evenly, the wet strips were extruded into strips. The wet strips were dried at 120°C for 10 hours and calcined at 680°C for 4 hours to obtain catalyst A2. The XRD characterization results of catalyst A2 are shown in Figure 2 The composition and physicochemical properties are shown in Table 1 and Table 1.

[0097] Preparation Example 3

[0098] Take 38.2g of zirconium hydroxide powder and 14.3g of all-silicon MFI molecular sieve, mix them evenly, add 48.0g of 5% by mass sulfuric acid aqueous solution, soak at 40°C for 4h, and dry the soaked solid at 60°C for 12h and 120°C for 12h.

[0099] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and mixed evenly with 3.4 g of pseudo-boehmite powder. A nitric acid aqueous solution with a concentration of 5.0 mass % was added for peptization. The ratio of the total mass of the nitric acid aqueous solution to the fine powder and the alumina precursor was 0.7:1. After kneading evenly, the wet strips were extruded into strips. The wet strips were dried at 120°C for 10 hours and calcined at 680°C for 4 hours to obtain catalyst A3. The XRD characterization results of catalyst A3 are shown in Figure 2 The composition and physicochemical properties are shown in Table 1 and Table 1.

[0100] Preparation Example 4

[0101] The method of Preparation Example 2 was followed, except that the amount of all-silicon MFI molecular sieve Si-1 used was 21 g. The prepared catalyst was denoted as A4, and the composition and physicochemical properties are shown in Table 1 and Table 1.

[0102] Preparation Example 5

[0103] 38.2 g of zirconium hydroxide powder was taken, 48.0 g of a 5 mass % sulfuric acid aqueous solution was added, and the mixture was immersed at 40° C. for 4 h. The immersed solid was dried at 60° C. for 12 h and 120° C. for 12 h.

[0104] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, 7.8 g of all-silicon MFI molecular sieve and 10.6 g of pseudo-boehmite powder were added thereto, mixed evenly, and 5.0 mass % nitric acid aqueous solution was added for peptization, the ratio of the total mass of the nitric acid aqueous solution to the fine powder and the alumina precursor was 0.6:1, and after kneading evenly, the strips were extruded, and the wet strips were dried at 120°C for 10 hours and calcined at 680°C for 4 hours to obtain catalyst A5. The composition and physicochemical properties of A5 are shown in Table 1 and Table 1.

[0105] Preparation Example 6

[0106] Take 38.2g of zirconium hydroxide powder and 6.0g of all-silicon MFI molecular sieve Si-1, mix them evenly, add 48.0g of 3% by mass sulfuric acid aqueous solution, soak at 40°C for 4h, and dry the impregnated solid at 60°C for 12h and 120°C for 12h.

[0107] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and mixed evenly with 38.3 g of pseudo-boehmite powder, and peptized by adding a nitric acid aqueous solution with a concentration of 5.0 mass %, the ratio of the nitric acid aqueous solution to the total mass of the fine powder and the alumina precursor being 0.6:1, and after kneading evenly, extruded into strips, and the wet strips were dried at 120° C. for 10 h and calcined at 630° C. for 4 h to obtain catalyst A6. The composition and physicochemical properties of catalyst A6 are shown in Table 1 and Table 1.

[0108] Comparative Preparation Example 1

[0109] 38.2 g of zirconium hydroxide powder was taken, 48.0 g of a 5 mass % sulfuric acid aqueous solution was added, and the mixture was immersed at 40° C. for 4 h. The immersed solid was dried at 60° C. for 12 h and 120° C. for 12 h.

[0110] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and mixed evenly with 16.6 g of pseudo-boehmite powder. A nitric acid aqueous solution with a concentration of 5.0 mass % was added for peptization. The ratio of the total mass of the nitric acid aqueous solution to the fine powder and the alumina precursor was 0.6:1. After kneading evenly, the wet strips were extruded into strips. The wet strips were dried at 120°C for 10 hours and calcined at 680°C for 4 hours to obtain catalyst DA1. The XRD characterization results of catalyst DA1 are shown in Figure 2 It can be seen that the catalyst DA1 does not contain the characteristic peak of the all-silicon MFI molecular sieve Si-1. The composition and physicochemical properties of the catalyst DA1 are shown in Table 1 and Table 1.

[0111] Comparative Preparation Example 2

[0112] Take 38.2g of zirconium hydroxide powder and 18.0g of all-silicon MFI molecular sieve, mix them evenly, add 48.0g of 5% by mass sulfuric acid aqueous solution, soak at 40°C for 4h, and dry the soaked solid at 60°C for 12h and 120°C for 12h.

[0113] The dried solid was ground into fine powder, passed through a 100-300 mesh sieve, and peptized with a nitric acid aqueous solution having a concentration of 5.0 mass %, the mass ratio of the nitric acid aqueous solution to the fine powder being 0.6:1, and kneaded evenly to form a strip, and the wet strip was dried at 120° C. for 10 h and calcined at 680° C. for 4 h to obtain catalyst DA2. The composition and physicochemical properties of catalyst DA2 are shown in Table 1 and Table 1.

[0114] Comparative Preparation Example 3

[0115] The method of Preparation Example 2 was followed, except that an equal mass of ZSM-5 molecular sieve (denoted as Si-2, produced by Changling Catalyst Company, with a silicon oxide / aluminum oxide molar ratio of 65, XRD characterization see Figure 1 )

[0116] The composition and physicochemical properties of the prepared catalyst, denoted as catalyst DA3, are shown in Table 1 and Supplementary Table 1.

[0117] Comparative Preparation Example 4

[0118] The method of Preparation Example 2 was followed, except that an equal mass of MCM-41 molecular sieve (denoted as Si-3, produced by Changling Catalyst Company, with a silicon oxide content of 99.7% by mass, XRD characterization see Figure 1 ) replaces the all-silica MFI molecular sieve.

[0119] The composition and physicochemical properties of the prepared catalyst, denoted as catalyst DA4, are shown in Table 1 and Supplementary Table 1.

[0120] Table 1

[0121]

[0122]

[0123] Table 1

[0124]

[0125] The following examples are used to illustrate the isobutane normalization method provided by the present invention.

[0126] The isobutane raw material used in the following examples includes: 0.04 mass % propane, 98.74 mass % isobutane, 0.76 mass % n-butane, and 0.46 mass % pentane.

[0127] The following examples adopt Figure 3 The isobutane normalization reaction system shown in FIG. Figure 3 As shown, the reaction system includes: a feed unit, a preheating device, a reactor 4, a light component separation device 5 and a deisobutanizer 6; the feed unit includes an isobutane raw material supply device and a hydrogen supply device, the isobutane raw material supply device includes a feed pump 1, and the preheating device includes a heat exchanger 2 and a heater 3. The catalyst is loaded in the reactor 4, and the loading and reaction conditions are shown in Tables 2 and 3.

[0128] When the reaction is started, the isobutane raw material is introduced into the feed pipeline through the feed pump 1, mixed with hydrogen, and then heated to the reaction temperature through the heat exchanger 2 and the heater 3 in sequence, and then sent to the reactor 4 to contact with the catalyst for isobutane normalization reaction. The obtained reaction product is sent to the heat exchanger 2 for heat exchange with the mixed raw material of isobutane raw material and hydrogen. The reaction product after heat exchange is sent to the light component separation device 5, and the light components are separated from the top of the tower, which are C1-C3 hydrocarbons and a small amount of H2; the C4 separated from the bottom of the tower + The hydrocarbons are sent to the deisobutanizer 6 for separation. Isobutane is separated from the top of the tower and recycled back to the feed unit to mix with the isobutane raw material. A small amount of C5+ Heavy components, and n-butane products are drawn out of the side line. Product sampling and analysis method: A bypass is provided on the main outlet line of reactor 4, and a sampling port is provided on the bypass. When sampling, the sampling cylinder is connected to the sampling port through a quick connector, and then the valves before and after the sampling cylinder are opened, and the sampling cylinder is replaced with the product. After the replacement is completed, the outlet valve of the sampling cylinder is closed, and after a certain amount of material to be analyzed is filled, the inlet valve is closed, and the quick connector is disconnected, and the sampling is completed. The samples are sent to the laboratory for analysis of the composition of the reactor outlet products, and the analysis results are listed in Tables 2 and 3.

[0129] Wherein, isobutane conversion rate (%) = ((mass of isobutane in the feedstock - mass of isobutane in the product) / mass of isobutane in the feedstock) × 100%;

[0130] n-Butane selectivity (%) = ((mass of n-butane in the product - mass of n-butane in the feed) / (mass of isobutane in the feed - mass of isobutane in the product)) × 100%;

[0131] Yield of normal butane (%) = ((mass of normal butane in the product - mass of normal butane in the raw material) / mass of isobutane in the raw material) × 100%.

[0132] Table 2

[0133]

[0134]

[0135] Table 3

[0136]

[0137] It can be seen from the results of Table 2 and Table 3 that the method for normalization of isobutane provided by the present invention has both high isobutane conversion and n-butane selectivity, and a high yield of n-butane. In a preferred embodiment, the method has a higher n-butane yield under the reaction conditions of low temperature and low hydrogen-to-hydrocarbon ratio, and is conducive to reducing the amount of hydrogen used, which can reduce energy consumption and raw material costs, and is conducive to reducing the difficulty of post-processing and separation, and has good reaction economy.

[0138] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for normalization of isobutane, characterized in that: The method comprises: contacting an isobutane raw material with a catalyst under hydrogen conditions and under isobutane normalization reaction conditions; Wherein, the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 .

2. The method according to claim 1, wherein: The isobutane normalization reaction conditions include: reaction temperature of 170-250° C., preferably 180-230° C.; pressure of 0.5-3.5 MPa, preferably 1-3 MPa; mass space velocity of isobutane raw material of 0.5-10 h -1 , preferably 1-5h -1 , more preferably 1.2-4h -1 ; The hydrogen / hydrocarbon molar ratio is 0.02-0.3, preferably 0.03-0.

2.

3. The method according to claim 1 or 2, wherein: In the catalyst, the density of the strong acid center is 0.5-1.5 μmol / m 2 .

4. The method according to any one of claims 1 to 3, wherein: In the catalyst, the mass ratio of the acidic active component calculated as ZrO2 to the mass ratio of the all-silicon molecular sieve calculated as SiO2 is 1:(0.1-1), preferably 1:(0.15-0.5).

5. The method according to any one of claims 1 to 4, wherein: The catalyst includes zirconium, silicon, aluminum and sulfur, calculated as zirconium oxide, silicon oxide, aluminum oxide and SO3 respectively. Based on the total mass of the catalyst, the content of zirconium oxide is 30-90wt%, the content of silicon oxide is 1-35wt%, the content of aluminum oxide is 5-50wt%, and the content of SO3 is 1-10wt%; preferably, based on the total mass of the catalyst, the content of zirconium oxide is 50-80wt%, the content of silicon oxide is 5-30wt%, the content of aluminum oxide is 5-30wt%, and the content of SO3 is 2-8wt%.

6. The method according to claim 5, wherein: The mass ratio of SO3 to ZrO2 is (0.02-0.12):1, preferably (0.03-0.08):

1.

7. The method according to any one of claims 1 to 6, wherein: The specific surface area of ​​the catalyst is 80-180m 2 / g, preferably 90-160m 2 / g, more preferably 100-150m 2 / g; Preferably, the aluminum oxide is γ-Al2O3.

8. The method according to any one of claims 1 to 7, wherein: The isobutane raw material includes isobutane and optional impurity components; Preferably, the isobutane content in the isobutane raw material is not less than 80wt%, preferably not less than 90wt%, more preferably 95-100wt%; Preferably, the impurity component is selected from at least one of C1-C3 alkanes, n-butane, C5+ alkanes, water and sulfur; Preferably, the content of C1-C3 alkanes in the isobutane raw material is less than 1wt%, preferably less than 0.5wt%; Preferably, the content of n-butane in the isobutane raw material is less than 2 wt%, preferably less than 1 wt%; Preferably, the water content in the isobutane feedstock is less than 5 ppmw, preferably less than 3 ppmw; Preferably, the sulfur content in the isobutane raw material is less than 10 ppmw, preferably less than 5 ppmw.

9. The method according to any one of claims 1 to 8, wherein: The method further comprises: preheating the isobutane raw material and hydrogen to the isobutane normalization reaction temperature, and then contacting with the catalyst; Preferably, the preheating includes primary preheating and secondary preheating, and the primary preheating includes: exchanging heat between the product of the normalization reaction of isobutane and the isobutane feedstock and / or hydrogen; Preferably, the method further comprises: separating and purifying the contact product, and using the separated isobutane to provide at least part of the isobutane raw material.

10. An isobutane normalization reaction system, characterized in that: The reaction system comprises: a feed unit, a preheating device, a reactor (4), a light component separation device (5) and a deisobutanizer (6); The feed unit is connected to the feed port of the preheating device to feed the isobutane raw material and hydrogen into the preheating device for preheating; The outlet of the preheating device is connected to the feed port of the reactor (4), and the preheated raw material is fed into the reactor (4) to contact with the catalyst; the catalyst includes an acidic active component SO4 2- / ZrO2, all-silicon molecular sieve with MFI structure and alumina; the density of the strong acid center in the catalyst is 0.1-2 μmol / m 2 ; The light component separation device (5) is used to separate the reaction products from the reactor (4), recover the obtained light components, and send the obtained heavy components to the deisobutanizer (6); wherein the light components include C1-C3 hydrocarbons and H2, and the heavy components include C4 + hydrocarbon; The deisobutanizer (6) is used to separate isobutane and normal butane products, and the separated isobutane is returned to the feed unit.

11. The reaction system according to claim 10, wherein: The feeding unit includes an isobutane raw material supply device and a hydrogen supply device; Preferably, the isobutane raw material supply device comprises a feed pump (1), and the isobutane raw material is transported to the preheating device through the feed pump (1) for preheating; Preferably, the preheating device comprises a heat exchanger (2) and a heater (3), The heat exchanger (2) is used to exchange heat between the reaction product from the reactor (4) and the isobutane raw material and hydrogen from the feed unit, and the reaction product after heat exchange is sent to the light component separation device (5), and the isobutane raw material and hydrogen are sent to the heater (3); The heater (3) is used to heat the isobutane raw material and hydrogen from the heat exchanger (2) to the isobutane normalization reaction temperature, and then feed them into the reactor (4).

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