Modified amorphous silica-alumina catalysts, methods for their preparation and use

Abstract

The present application relates to the field of catalyst preparation, discloses a modified amorphous silicon aluminum catalyst and its preparation method and application, the method comprises the following steps: (1) copper zinc component is pretreated by hydrogenation; (2) amorphous silicon aluminum catalyst is mixed with the product obtained in step (1), and is sequentially carried out first drying, first calcination and hydrothermal treatment;Wherein, the silicon aluminum ratio of the amorphous silicon aluminum catalyst is 1.5-3, preferably 1.8-2.5;The copper zinc component has the following general formula composition: Cu a ZnAl b O z , wherein a is 0.1-10, b is 0.1-5, and z is the number of oxygen atoms satisfying the valence of each metal element.The catalyst prepared by the preparation method of the present application has high carbon four olefin conversion rate and carbon eight olefin selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, and more particularly to a modified amorphous silica-alumina catalyst and its preparation method, as well as a method for preparing high-octane gasoline components from mixed C4 olefins using the catalyst in a non-selective stoichiometric manner. Background Technology

[0002] C4 hydrocarbons can be produced as byproducts in oil refineries' catalytic cracking, ethylene cracking, viscous cracking, coking, and thermal cracking units, with catalytic cracking and ethylene cracking accounting for 80%. C4 fractions contain a high proportion of C4 olefins, among which isobutylene, butene-1, butene-2, and butadiene are important chemical feedstocks. One important use of isobutylene is in the production of high-octane methyl tert-butyl ether (MTBE). MTBE capacity increased to 12 million tons / year in 1992, 20 million tons / year in 1993-1994, and rose to 30 million tons / year in 1995, with the United States accounting for 53% of the total capacity. However, global demand for MTBE has declined sharply over the past decade because the United States and Canada banned MTBE in 2005, and by 2011, MTBE capacity had decreased to 12 million tons / year. Currently, 62% of MTBE capacity is concentrated in Asia.

[0003] my country has abundant C4 hydrocarbon (liquefied petroleum gas) resources. In 2016, the country's crude oil processing volume reached 541 million tons, with refineries producing approximately 17 million tons of C4 hydrocarbons as a byproduct. Cracking C4 hydrocarbons accounted for about one-quarter of total ethylene production, producing 4.25 million tons of C4 hydrocarbons as a byproduct. Currently, my country's total C4 hydrocarbon reserves are as high as 25 million tons. The various components of C4 hydrocarbons have wide applications. They can be used as fuels through aromatization, alkylation, and isomerization, and can also be used to produce various chemical products such as methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl ethyl ketone (MEK), and sec-butyl acetate. MTBE, as a significant pathway for isobutylene consumption, plays a crucial role in the downstream utilization of butene-1 and butene-2. Therefore, with the ban on MTBE, liquefied petroleum gas urgently needs to find new chemical pathways to reconnect the bridge for C4 hydrocarbon utilization.

[0004] Fully alkylation reaction (non-selective alkylation reaction) involves the reaction between isobutylene, n-butene, cis-2-butene, and trans-2-butene to produce polyolefins. Polyolefins produced by alkylation reactions have a high degree of branching and are characterized by high research octane numbers, low vapor pressures, and are free of sulfur and aromatics, making them ideal additives for clean gasoline.

[0005] Currently, there are three main industrially mature processes globally for producing petroleum products that meet international additive standards from olefin full smothermal synthesis: the SPAC process from UOP (U.S.), the non-selective MOGD smothermal synthesis process from the former Mobil (U.S.), and the Polynaphtha process from Axens (France). Among these, UOP's SPAC process is characterized by its simple process flow, readily available and inexpensive solid phosphoric acid catalysts, and long lifespan, making it one of the most widely used full smothermal processes in the world. However, with increasingly stringent environmental regulations, the drawbacks of solid phosphoric acid catalysts—such as easy sludge formation, non-renewability, and the difficulty of post-treatment due to strong acidity—have become increasingly prominent. Although researchers both domestically and internationally have conducted extensive research on solid phosphoric acid catalysts (CN1997450A, CN100496724C, CN1226095C, etc.), employing various novel phosphoric acid supports such as diatomaceous earth, silica, and activated carbon to continuously extend catalyst lifespan and catalytic activity, none of these studies have solved the problems of easy sludge formation, deactivation, and non-renewability of solid phosphoric acid catalysts. Mobil's MOGD process uses ZSM-5 molecular sieve catalysts, offering flexible reaction conditions to meet diverse market demands. However, this gas-solid reaction involves extremely high temperatures, high energy consumption, and difficult plant construction, thus limiting its large-scale adoption. Axens' Polynaphtha process uses a co-precipitation method to prepare silica-alumina catalysts. These catalysts are regenerable, have a long lifespan, and are easy to handle after deactivation. The process is also simple, requiring no modifiers. However, the co-precipitation method produces a low amount of Brønsted acid (B acid) and a low B acid / L acid ratio, requiring higher reaction temperatures and pressures. This results in significant olefin polymerization, with only about 40% selectivity for C8 olefins, limiting their application to diesel component modifiers. However, due to my country's focus on gasoline development, the market for the resulting blended diesel is limited, hindering large-scale application. Therefore, developing a novel blended gasoline process has become a research hotspot. Summary of the Invention

[0006] This invention addresses the problem that mixed C4 olefins, especially coking-containing mixed C4 olefins, are prone to catalyst deactivation and low C8 olefin selectivity during non-selective fusion processes. It provides a modified amorphous silica-alumina catalyst and its preparation method, as well as a method for preparing high-octane gasoline components from mixed C4 olefins using this catalyst through non-selective fusion.

[0007] To achieve the above objectives, the present invention provides a method for preparing a modified amorphous silica-alumina catalyst, the method comprising the following steps:

[0008] (1) The copper-zinc components were pretreated by hydrogenation;

[0009] (2) The amorphous silica-alumina catalyst is mixed with the product obtained in step (1), and then subjected to first drying, first calcination and hydrothermal treatment in sequence;

[0010] The amorphous silica-alumina catalyst has a silica-alumina ratio of 1.5-3, preferably 1.8-2.5.

[0011] The copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, and z is the number of oxygen atoms that satisfy the oxidation states of each metal element.

[0012] Preferably, in step (1), the preparation method of the copper-zinc component includes: contacting the precipitant with a copper source, a zinc source, and a second aluminum source under pH 5-9 conditions, followed by a second aging, washing, a second drying, and a second calcination to obtain the copper-zinc component.

[0013] Preferably, the precipitant is an alkali or an alkaline salt.

[0014] Preferably, in step (1), the hydrogenation pretreatment results in the proportion of 0-valent copper and +1-valent copper in the copper-zinc composition to more than 50% of the total copper content, preferably more than 70%; more preferably, the hydrogenation pretreatment results in the proportion of 0-valent copper and +1-valent copper in the copper-zinc composition to 30-50% of the total copper content.

[0015] Preferably, in step (1), the conditions for hydrogenation pretreatment include: reduction with hydrogen or hydrogen-containing gas at 150-300°C and 0.1-8MPa for 2-40 hours.

[0016] Preferably, in step (2), the preparation method of the amorphous silicon-aluminum catalyst includes: aging a silicon source and a first aluminum source under conditions of pH 8-10.5 and 40-80℃, then washing and filtering the resulting aging product, and then contacting the filtered solid precipitate with an acidic solution for filtration and drying.

[0017] Preferably, in step (2), the silicon source is selected from one or more of water glass, sodium silicate, alkaline silica sol, tetraethoxysilane and tetramethoxysilane, and the aluminum source is selected from one or more of aluminum nitrate, aluminum sulfate or aluminum chloride; more preferably, the weight ratio of silicon source based on silicon oxide to aluminum source based on aluminum oxide is 1:(0.25-1).

[0018] Preferably, in step (2), the contact between the filtered solid precipitate and the acidic solution is carried out at a weight ratio of precipitate dry basis: acidic substance: H2O = 1:(0.02-0.2):(5-30); preferably, the contact treatment is carried out at 20-60°C for more than 0.2 hours; preferably, the acidic substance in the acidic solution is selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, ammonium sulfate, ammonium chloride and ammonium nitrate.

[0019] Preferably, in step (2), the pore size of the amorphous silica-alumina catalyst is 20-50 nm.

[0020] Preferably, in step (2), the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27° in the XRD pattern.

[0021] Preferably, in step (2), the amount of the copper-zinc component is 1-10% by mass of the amorphous silica-alumina catalyst, preferably 3-5% by mass.

[0022] Preferably, in step (2), the conditions for the first calcination include: an inert atmosphere, a temperature of 400-580°C, and a time of 1-5 hours.

[0023] Preferably, in step (2), the conditions for hydrothermal treatment include: a temperature of 200-350℃, a pressure of atmospheric pressure to 0.5MPa, and a time of 1-5 hours.

[0024] A second aspect of the present invention provides a modified amorphous silica-alumina catalyst, which comprises an amorphous silica-alumina catalyst and a copper-zinc component supported thereon. The silica-alumina ratio of the amorphous silica-alumina catalyst is 1.5-3, preferably 1.8-2.5, and the copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, z is the number of oxygen atoms satisfying the valence of each metal element, and the content of the copper-zinc component is 1-10% by mass of the amorphous silica-alumina catalyst, preferably 3-5% by mass, and in the modified amorphous silica-alumina catalyst, 0-valent copper and +1-valent copper account for more than 50% of the total copper content, preferably more than 70%.

[0025] Preferably, in the modified amorphous silica-alumina catalyst, 0-valent copper accounts for 30-50% of the total copper content, and +1-valent copper accounts for 30-50% of the total copper content.

[0026] Preferably, the amorphous silica-alumina catalyst has a pore size of 20-50 nm.

[0027] Preferably, the specific surface area of ​​the amorphous silica-alumina catalyst is less than 250 m². 2 / g.

[0028] Preferably, the XRD pattern of the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27°.

[0029] The third aspect of the present invention provides the application of the modified amorphous silica-alumina catalyst obtained by the preparation method of the first aspect above, or the modified amorphous silica-alumina catalyst of the second aspect, in C4 assemblies, preferably in C4 assemblies with a basic nitrogen content of 0-30 ppm.

[0030] A fourth aspect of the present invention provides a method for carbon-4 superposition, the method comprising: contacting a mixed carbon-4 with a superposition catalyst under superposition reaction conditions, wherein the superposition catalyst is a modified amorphous silica-alumina catalyst obtained by the preparation method of the first aspect above, or a modified amorphous silica-alumina catalyst of the second aspect.

[0031] Preferably, the basic nitrogen content of the mixed C4 is 0-30 ppm.

[0032] Preferably, the superposition reaction conditions include: a temperature of 160-220℃, a pressure of 2-6 MPa, and a space velocity of 0.1-2 h⁻¹. -1 .

[0033] Preferably, the C4 stacking is carried out in a fixed-bed reactor, and more preferably in a downflow fixed-bed reactor.

[0034] Through the above technical solution, by using copper-zinc components for modification, the modified amorphous silica-alumina catalyst of the present invention has a 5-20% higher C4 olefin conversion rate than the unmodified amorphous silica-alumina catalyst; it can use mixed C4 olefins from coking sources (e.g., coking C4 olefins with a basic nitrogen content of 0-15 ppm) as reaction raw materials; the non-selective octaolefin content is high; isobutylene is basically completely converted, and the separated mixed C4 olefins can be used as high-quality raw materials for alkylation. Detailed Implementation

[0035] 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.

[0036] The first aspect of this invention provides a method for preparing a modified amorphous silica-alumina catalyst, the method comprising the following steps:

[0037] (1) The copper-zinc components were pretreated by hydrogenation;

[0038] (2) The product obtained in step (1) is mixed with an amorphous silica-alumina catalyst and subjected to a first drying, a first calcination and a hydrothermal treatment in sequence;

[0039] The amorphous silica-alumina catalyst has a silica-alumina ratio of 1.5-3, preferably 1.8-2.5.

[0040] The copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, and z is the number of oxygen atoms that satisfy the oxidation states of each metal element.

[0041] According to the present invention, the silicon-to-aluminum ratio of the amorphous silicon-aluminum catalyst can be, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.

[0042] According to the present invention, a can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10, etc.; b and c can each independently be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5, etc.

[0043] According to a preferred embodiment of the present invention, the amorphous silica-alumina catalyst has the following general formula composition: (0-0.3)Na2O·(50-80)SiO2·(20-50)Al2O3.

[0044] According to the present invention, in step (1), in order to obtain the copper-zinc component having the above composition, a co-precipitation method can be used for preparation. Specifically, the preparation method of the copper-zinc component may include, for example, contacting a precipitant with a copper source, a zinc source, and a second aluminum source under conditions of pH 2-9, preferably 5-8.5, followed by a second aging, washing, a second drying, and a second calcination to obtain the copper-zinc component.

[0045] As the copper source, zinc source, and second aluminum source, soluble salts containing copper, zinc, and aluminum are preferably used, with nitrates or hydrochlorides being more preferred. The copper source may be selected from one or more of copper nitrate, copper sulfate, and copper chloride. The zinc source may be selected from one or more of zinc nitrate, zinc sulfate, and zinc chloride. The second aluminum source may be selected from one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride. Additionally, as the precipitating agent, it may be an alkali (such as sodium hydroxide, potassium hydroxide), an alkaline salt (such as sodium carbonate, potassium carbonate), or ammonia, such as sodium carbonate.

[0046] The contact between the precipitant and the copper source, zinc source, and second aluminum source can be achieved by adding a solution containing the copper source, zinc source, and second aluminum source to the precipitant solution, or by adding the precipitant solution to a solution containing the copper source, zinc source, and second aluminum source, or by contacting the solutions containing the copper source and second aluminum source, and the solutions containing the zinc source and second aluminum source, separately with the precipitant solution and then mixing the contact products. In the above solution, the concentrations of the zinc source, copper source, and second aluminum source (calculated as zinc ions, copper ions, or aluminum ions) can each be independently 0.1-5 mol / L, preferably 0.2-2.5 mol / L, more preferably 1-2.5 mol / L. The concentration of the precipitant solution can be 0.1-5 mol / L, preferably 0.5-2 mol / L. The volume ratio of the precipitant solution to the total volume of the zinc source, copper source, and second aluminum source is 1-10:1, preferably 3-8:1.

[0047] As a preferred method for preparing the copper-zinc component, the conditions for the second aging may include: a temperature of 30-80℃, preferably 50-70℃; a time of 2-20 hours, preferably 5-10 hours; and a pH of 6-9, preferably 7.5-8.5. The conditions for the second drying may include: a temperature of 80-150℃, preferably 105-120℃; and a time of 1-6 hours, preferably 2-4 hours. The conditions for the second calcination may include: a temperature of 200-450℃, preferably 300-380℃; and a time of 1-6 hours, preferably 2-4 hours.

[0048] According to the present invention, in step (1), the copper-zinc component is made suitable for modification of the C4 olefin non-selective chelate catalyst through hydrogenation pretreatment, thereby facilitating the obtaining of a modified amorphous silica-alumina catalyst with better non-selective chelate effect. Preferably, the hydrogenation pretreatment results in 0-valent copper and +1-valent copper accounting for more than 50% of the total copper content in the copper-zinc component, more preferably more than 70%; more preferably, the hydrogenation pretreatment results in 30-50% of the total copper content in the copper-zinc component and 30-50% of the total copper content in the +1-valent copper.

[0049] The conditions for the hydrogenation pretreatment may include: reduction with hydrogen or a hydrogen-containing gas at 150-300°C and 0.1-8 MPa for 2-40 hours; preferably, reduction at 200-280°C and 3-6 MPa for 5-10 hours. The hydrogen-containing gas may be a mixture of hydrogen and an inert gas, wherein the hydrogen content is 5-20% by volume.

[0050] According to the present invention, in step (2), the amorphous silicon-aluminum catalyst can be an amorphous silicon-aluminum catalyst commonly used for C4 non-selective superposition, for example, it can be prepared by the following method: a silicon source and a first aluminum source are subjected to a first aging at pH 8-10.5 and 40-80°C, and then the resulting aging product is washed and filtered, and the filtered solid precipitate is contacted with an acidic solution, and then filtered and dried.

[0051] Specifically, the silicon source may be selected from one or more of water glass, sodium silicate, alkaline silica sol, tetraethoxysilane, and tetramethoxysilane, and the first aluminum source may be selected from one or more of aluminum nitrate, aluminum sulfate, or aluminum chloride. Furthermore, the weight ratio of the silicon source (based on silicon oxide) to the first aluminum source (based on aluminum oxide) may be 1:(0.25-1), preferably 1:(0.4-0.7).

[0052] Preferably, the pH is adjusted to the aforementioned range by adding an alkaline solution. The alkaline solution used can be selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, and sodium aluminate. When sodium aluminate is used as the alkaline solution, its alumina content is included in the first aluminum source. Furthermore, the conditions for the first aging process may include: a temperature of 40-80°C, preferably 60-75°C; a time of 5-20 hours, preferably 10-15 hours; and a pH of 8-10.5, preferably 9-10.

[0053] Preferably, the contact between the filtered solid precipitate and the acidic solution is carried out at a weight ratio of precipitate dry basis: acidic substance: H2O = 1:(0.02-0.2):(5-30), preferably 1:(0.05-0.15):(10-20). The acidic substance is the solute in the acidic solution. The contact is preferably carried out at 20-60°C, preferably 30-50°C, for at least 0.2 hours, preferably 0.2-1 hours. The acidic solution used can be an acid or a solution of a strong acid-weak base salt, for example, a solution selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, ammonium sulfate, ammonium chloride, and ammonium nitrate, with a concentration of 0.01-2 mol / L, preferably 0.1-1 mol / L. Subsequent drying conditions can be, for example, 80-110°C for 1-5 hours.

[0054] According to the present invention, the amorphous silica-alumina catalyst described above preferably has the following characteristics, which helps to further improve the conversion rate of C4 olefins and the selectivity of C8 olefins.

[0055] Preferably, the amorphous silica-alumina catalyst has a pore size of 20-50 nm, more preferably 30-50 nm.

[0056] Preferably, the XRD pattern of the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27°.

[0057] According to the present invention, in step (2), the amorphous silica-alumina catalyst is modified by using a copper-zinc component. To improve the C4 olefin conversion and C8 olefin selectivity of the obtained catalyst, preferably, the amount of the copper-zinc component is 1-10% by mass of the amorphous silica-alumina catalyst, more preferably 3-5% by mass. Furthermore, when the product obtained in step (1) is mixed with the amorphous silica-alumina catalyst, it is preferable to stir and mix for at least 3 minutes, for example, 5-20 minutes, so that the hydrogenated copper-zinc component is thoroughly mixed with the amorphous silica-alumina catalyst.

[0058] According to the present invention, in step (2), the conditions for the first drying may include: a temperature of 80-150°C, preferably 95-120°C, more preferably 105-120°C; and a time of 1-6 hours, preferably 2-4 hours. The conditions for the first calcination may include: under an inert atmosphere, a temperature of 400-580°C, preferably 400-550°C, more preferably 500-550°C; and a time of 1-6 hours, preferably 2-4 hours. The inert atmosphere may be a nitrogen atmosphere and / or an inert gas atmosphere such as argon. The conditions for the hydrothermal treatment may include: a temperature of 200-400°C, preferably 240-350°C, more preferably 240-300°C; a pressure of atmospheric pressure to 0.5 MPa, preferably atmospheric pressure to 0.2 MPa; and a time of 1-8 hours, preferably 2-5 hours, more preferably 2-4 hours.

[0059] A second aspect of the present invention provides a modified amorphous silica-alumina catalyst, which comprises an amorphous silica-alumina catalyst and a copper-zinc component supported thereon. The silica-alumina ratio of the amorphous silica-alumina catalyst is 1.5-3, preferably 1.8-2.5, and the copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, z is the number of oxygen atoms satisfying the valence of each metal element, and the content of the copper-zinc component is 1-10% by mass of the amorphous silica-alumina catalyst, preferably 3-5% by mass, and in the modified amorphous silica-alumina catalyst, 0-valent copper and +1-valent copper account for more than 50% of the total copper content, preferably more than 70%.

[0060] According to the present invention, in the modified amorphous silica-alumina catalyst, copper exists in the forms of 0, +1, and / or +2 valences. Through hydrogenation reduction pretreatment, the 0-valent copper and +1-valent copper account for more than 50% of the total copper content, thereby enabling the obtained modified amorphous silica-alumina catalyst to exhibit better C4 olefin catalytic activity. In a specific embodiment of the present invention, the 0-valent copper accounts for 30-50% of the total copper content, and the +1-valent copper accounts for 30-50% of the total copper content; furthermore, the +2-valent copper accounts for less than 30% of the total copper content, for example, 10-30%.

[0061] The modified amorphous silica-alumina catalyst described above can be prepared using the preparation method of the first aspect of this invention.

[0062] According to the present invention, the amorphous silica-alumina catalyst described above preferably has the following characteristics, which helps to further improve the conversion rate of C4 olefins and the selectivity of C8 olefins, and is particularly suitable for the synthesis of coking C4 olefins with a basic nitrogen content of 0-30 ppm.

[0063] Preferably, the amorphous silica-alumina catalyst has a pore size of 20-50 nm, more preferably 30-50 nm.

[0064] Preferably, the specific surface area of ​​the amorphous silica-alumina catalyst is less than 250 m². 2 / g, preferably 200-250m 2 / g.

[0065] Preferably, the XRD pattern of the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27°.

[0066] In addition, to facilitate the reaction, the particle size of the modified amorphous silica-alumina catalyst is preferably 20-40 mesh.

[0067] The third aspect of the present invention provides the application of the modified amorphous silica-alumina catalyst obtained by the preparation method of the first aspect of the present invention, or the modified amorphous silica-alumina catalyst of the second aspect, in C4 assemblies, preferably in C4 assemblies in which the basic nitrogen content of the raw material is 0-30 ppm.

[0068] In this invention, the alkaline nitrogen content of the composite raw material can be, for example, 0 ppm, 1 ppm, 2 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm or 30 ppm.

[0069] A fourth aspect of the present invention provides a method for carbon-4 superposition, the method comprising: contacting a mixed carbon-4 with a superposition catalyst under superposition reaction conditions, wherein the superposition catalyst is a modified amorphous silica-alumina catalyst obtained by the preparation method of the first aspect of the present invention, or a modified amorphous silica-alumina catalyst of the second aspect.

[0070] Preferably, the superposition reaction conditions include: a temperature of 160-220℃, a pressure of 2-6 MPa, and a space velocity of 0.1-2 h⁻¹. -1 More preferably, the temperature is 170-190℃, the pressure is 4.5-5.5MPa, and the space velocity is 0.5-1.5h. -1 .

[0071] The above-mentioned C4 superposition method is preferably carried out in a fixed-bed reactor, which can be either upflow or downflow, with downflow being preferred.

[0072] The mixed C4 used as the reaction feedstock has no particular source limitation and can be C4 byproducts of ethylene cracking units and refinery C4 components. Refinery C4 includes C4 byproducts from catalytic cracking, viscous cracking, thermal cracking, and delayed coking in refineries; C4 byproducts from aromatics reforming; C4 byproducts from coal chemical methanol-to-olefins units; and recovered C4 from oilfield gas and natural gas. The amount of saturated C4 hydrocarbons in the feedstock does not affect this method, but excessive saturated hydrocarbons will increase the reaction temperature and energy consumption. Therefore, it is preferable that the content of saturated C4 hydrocarbons in the mixed C4 is below 70% by volume.

[0073] Furthermore, the modified amorphous silica-alumina catalyst of this invention can be applied to C4 olefins from coking sources. Even with a basic nitrogen content of less than 30 ppm in the olefin feedstock, it can still achieve good C4 olefin conversion and C8 olefin selectivity, and has a better catalyst activity retention effect, extending the catalyst activation interval.

[0074] In this invention, the alkaline nitrogen content of the composite raw material can be, for example, 0 ppm, 1 ppm, 2 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm or 30 ppm.

[0075] A specific method for C4 superposition may include: pumping mixed C4 into a fixed-bed reactor packed with modified amorphous silica-alumina catalyst, using a top-in, bottom-out feeding method, analyzing the product online via gas-liquid chromatography after it flows out of the reactor, controlling the reaction pressure with a back pressure valve, and finally storing the product in a product storage tank.

[0076] The present invention will be described in detail below through embodiments.

[0077] In this invention, the alkaline nitrogen content is determined by the industry standard: SH / T 0162-1992 Determination of Alkaline Nitrogen in Petroleum Products; the valence distribution of copper is obtained by peak analysis using XPS Auger copper spectrometry.

[0078] Example 1

[0079] This embodiment illustrates the use of nCu / n Zn An amorphous silica-alumina catalyst was modified with a 1:1 copper-zinc composition and subjected to a non-selective superposition reaction. The preparation method of the modified catalyst is as follows:

[0080] (1) Preparation of copper-zinc components n was prepared by co-precipitation method Cu / n Zn It is a 1 / 1 copper-zinc composition.

[0081] a) Dissolve 0.5 mol Cu(NO3)2·3H2O and 0.5 mol AlCl3·6H2O in 200 mL of deionized water to prepare mixed solution A, and dissolve 0.5 mol Zn(NO3)2·6H2O and 0.5 mol AlCl3·6H2O in 200 mL of deionized water to prepare mixed solution B.

[0082] b) Add 50 mL of deionized water to reaction vessel 1. Add mixed solution A and sodium carbonate solution (concentration 1.0 mol / L) to reaction vessel 1 in parallel and stir. The molar ratio of sodium carbonate to the total amount of copper and aluminum is 2.0. The temperature is 60℃, the pH value is 7.5, and the time is 1.0 hour to obtain slurry I.

[0083] c) Add 50 mL of deionized water to reaction vessel 2. Add mixed solution B and sodium carbonate solution (concentration 1.0 mol / L) to reaction vessel 2 in parallel. The molar ratio of sodium carbonate to the total amount of zinc and aluminum is 2.0. The temperature is 60℃, the pH value is 9.2, and the time is 2.0 hours to obtain slurry II.

[0084] d) Mix slurry I and II in a volume ratio of 1:1. The resulting mixed slurry is aged under stirring conditions. The aging pH value is 7.8, the aging temperature is 70℃, and the aging time is 5.5 hours. The aged slurry is filtered, and the filter cake is washed 3 times with deionized water. The filter cake is dried at 110℃ for 5 hours and calcined at 360℃ for 3.5 hours.

[0085] (2) Hydrogenation pretreatment of copper-zinc components

[0086] The copper-zinc component obtained in step (1) was pressed into 20-40 mesh solid particles, and 20.0 g was loaded into a fixed-bed reactor. 10% hydrogen gas (a mixture of 10% hydrogen and 90% nitrogen, hereinafter the same) was introduced at a pressure of 0.20 MPa, and the temperature was increased at a rate of 0.5 °C / min within the range of room temperature to 280 °C. The catalyst was reduced at 280 °C for 4.0 h, and then cooled to room temperature. XPS analysis revealed that 0-valent copper accounted for 39.5% of the total copper content, +1-valent copper accounted for 38.2%, and +2-valent copper accounted for 22.3%.

[0087] (3) Preparation of amorphous silica-alumina catalyst

[0088] The silicon source (35g SiO2 / L water glass, 1000mL) and the alkaline solution (sodium hydroxide, 1.0mol / L, 250mL) were thoroughly mixed at 60℃. Then, the aluminum source (90g Al2O3 / L sodium aluminate, 300mL) was added under stirring. The pH of the resulting slurry was adjusted to 9.4. The slurry was then dynamically aged at a constant temperature of 70℃ for 12 hours. After washing and filtration, the resulting solid precipitate was contacted with an acidic solution (NH4Cl, 0.5mol / L) at 60℃ for 0.5 hours at a weight ratio of precipitate dry basis: NH4Cl: H2O = 1:0.1:15. After filtration, the precipitate was dried at 100℃ for 3 hours to obtain an amorphous silicon-aluminum catalyst.

[0089] The XRD pattern of this amorphous silica-alumina catalyst showed only one diffuse diffraction peak at 25°–27°, indicating a pore size of 35.4 nm and a specific surface area of ​​248 m². 2 / g, with a silicon-to-aluminum ratio of 2.24.

[0090] (4) Modification treatment of amorphous silica-alumina catalysts

[0091] Add 3.5g of copper-zinc component to 100g of amorphous silica-alumina catalyst, stir evenly, dry at 100℃ for 2 hours, then calcine at 450℃ for 3 hours under nitrogen atmosphere, and then perform hydrothermal treatment at 350℃ for 5 hours to obtain modified amorphous silica-alumina catalyst.

[0092] The modified amorphous silica-alumina catalyst obtained was used for the non-selective stoichiometry reaction of C4 olefins. A mixture of C4 olefin products from catalytic cracking and coking at Cangzhou Refinery (in mol%: n-butane 18.783%, isobutane 38.258%, n-butene 11.153%, isobutene 10.096%, cis-butene 8.364%, trans-butene 12.086%, C3 0.56%, isopentene 0.65%, butadiene 0.05%; basic nitrogen content 10 ppm) was used as feedstock, and the reaction was carried out at 170℃, 5.2 MPa, and a space velocity of 0.5 h⁻¹. -1 The modified amorphous silica-alumina catalyst prepared above was reacted under the specified reaction conditions. The reaction products were analyzed by online gas chromatography. After product collection, the light and heavy components were separated using a distillation column. The analytical results are shown in Table 1.

[0093] Example 2

[0094] This embodiment illustrates the use of n Cu / n Zn A copper-zinc component of 1 / 2 was used to modify an amorphous silica-alumina catalyst, which was then subjected to a non-selective superposition reaction.

[0095] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that slurry I and II were mixed in a volume ratio of 1:2 during the preparation of the copper-zinc component.

[0096] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0097] Example 3

[0098] This embodiment illustrates the use of n Cu / n Zn A copper-zinc composition of 2 / 1 was used to modify an amorphous silica-alumina catalyst, followed by a non-selective superposition reaction.

[0099] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that slurry I and II were mixed in a volume ratio of 2:1 during the preparation of the copper-zinc component.

[0100] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0101] Example 4

[0102] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the amount of copper and zinc components used in the preparation of the copper-zinc components was 5.0% of the mass of the amorphous silica-alumina catalyst.

[0103] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0104] Example 5

[0105] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the amount of copper and zinc components used in the preparation of the copper-zinc components was 4.0% of the mass of the amorphous silica-alumina catalyst.

[0106] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0107] Example 6

[0108] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the amount of copper and zinc components used in the preparation of the copper-zinc components was 1.0% of the mass of the amorphous silica-alumina catalyst.

[0109] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0110] Example 7

[0111] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the amount of copper and zinc components used in the preparation of the copper-zinc components was 10.0% of the mass of the amorphous silica-alumina catalyst.

[0112] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0113] Example 8

[0114] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the silica-alumina ratio of the amorphous silica-alumina catalyst was 1.85.

[0115] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0116] Example 9

[0117] The same stoichiometric reaction of mixed C4 was carried out as in Example 1, except that the basic nitrogen content in the mixed C4 olefin product used was 2 ppm. The analytical results of the reaction products are shown in Table 1.

[0118] Comparative Example 1

[0119] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, but without hydrogenation pretreatment.

[0120] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0121] Comparative Example 2

[0122] Amorphous silica-alumina catalyst was prepared according to the method of Example 1, and the amorphous silica-alumina catalyst was directly used to carry out the mixed C4 superposition reaction in the same way as in Example 1. The analysis results of the reaction products are shown in Table 1.

[0123] Comparative Example 3

[0124] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the silica-alumina ratio of the amorphous silica-alumina catalyst was 1.3.

[0125] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0126] Comparative Example 4

[0127] The modified amorphous silica-alumina catalyst was prepared according to the method of Example 1, except that the silica-alumina ratio of the amorphous silica-alumina catalyst was 3.2.

[0128] The same superposition reaction of mixed C4 was carried out as in Example 1, and the analytical results of the reaction products are shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] Where, α 总 For the total conversion of C4 olefins, α 反 The conversion rate of 2-trans-butene, α 正 The conversion rate of n-butene, α 异 For the conversion rate of isobutylene, α 顺 S represents the conversion rate of 2-cis-butene. C8 It is selective for C8 olefins.

[0133] As can be seen from the results in Table 1, the examples prepared by the method of the present invention have higher C4 olefin conversion and C8 olefin selectivity, and are suitable for coking C4 olefin alkylation with basic nitrogen content of 0-30 ppm.

[0134] 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 preparing a modified amorphous silica-alumina catalyst, characterized in that, The method includes the following steps: (1) The copper-zinc components are subjected to hydrogenation pretreatment; (2) The amorphous silica-alumina catalyst is mixed with the product obtained in step (1), and then subjected to first drying, first calcination and hydrothermal treatment in sequence; The amorphous silica-alumina catalyst has a silica-alumina ratio of 1.5-3. The copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, and z is the number of oxygen atoms that satisfy the oxidation states of each metal element; In step (1), the conditions for hydrogenation pretreatment include: reduction with hydrogen or hydrogen-containing gas at 150-300℃ and 0.1-8MPa for 2-40 hours; in the modified amorphous silica-alumina catalyst, 0-valent copper accounts for 30-50% of the total copper content and +1-valent copper accounts for 30-50% of the total copper content.

2. The preparation method according to claim 1, wherein, In step (1), the preparation method of the copper-zinc component includes: contacting the precipitant with a copper source, a zinc source and a second aluminum source under pH 5-9 conditions, and then subjecting the process to a second aging, washing, a second drying and a second calcination to obtain the copper-zinc component.

3. The preparation method according to claim 2, wherein, The precipitant is an alkali or an alkaline salt.

4. The preparation method according to claim 1, wherein, The amorphous silica-alumina catalyst has a silica-alumina ratio of 1.8-2.

5.

5. The preparation method according to any one of claims 1-4, wherein, In step (2), the preparation method of the amorphous silicon-aluminum catalyst includes: aging the silicon source and the first aluminum source under the conditions of pH 8-10.5 and 40-80℃, then washing and filtering the resulting aging product, and then contacting the filtered solid precipitate with an acidic solution for filtration and drying.

6. The preparation method according to claim 5, wherein, The silicon source is selected from one or more of water glass, sodium silicate, alkaline silica sol, tetraethoxysilane, and tetramethoxysilane, and the aluminum source is selected from one or more of aluminum nitrate, aluminum sulfate, or aluminum chloride.

7. The preparation method according to claim 5, wherein, The weight ratio of silicon source (calculated as silicon oxide) to aluminum source (calculated as aluminum oxide) is 1:(0.25-1).

8. The preparation method according to claim 5, wherein, The solid precipitate obtained from filtration is contacted with the acidic solution at a weight ratio of precipitate dry basis: acidic substance: H2O = 1:(0.02-0.2):(5-30).

9. The preparation method according to claim 5, wherein, Contact treatment at 20-60℃ for more than 0.2 hours.

10. The preparation method according to claim 5, wherein, The acidic substance in the acidic solution is selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, ammonium sulfate, ammonium chloride, and ammonium nitrate.

11. The preparation method according to any one of claims 1-4, wherein, In step (2), the pore size of the amorphous silica-alumina catalyst is 20-50 nm; And / or, the XRD pattern of the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27°.

12. The preparation method according to any one of claims 1-4, wherein, In step (2), the amount of copper-zinc component used is 1-10% of the mass of the amorphous silica-alumina catalyst.

13. The preparation method according to claim 12, wherein, In step (2), the amount of copper-zinc component used is 3-5% of the mass of the amorphous silica-alumina catalyst.

14. The preparation method according to any one of claims 1-4, wherein, In step (2), the conditions for the first calcination include: an inert atmosphere, a temperature of 400-580℃, and a time of 1-5 hours.

15. The preparation method according to any one of claims 1-4, wherein, In step (2), the conditions for hydrothermal treatment include: temperature of 200-350℃, pressure of atmospheric pressure to 0.5MPa, and time of 1-5 hours.

16. A modified amorphous silica-alumina catalyst, characterized in that, This modified amorphous silica-alumina catalyst consists of an amorphous silica-alumina catalyst and a copper-zinc component supported thereon. The silica-alumina ratio of the amorphous silica-alumina catalyst is 1.5-3, and the copper-zinc component has the following general formula: Cu a ZnAl b O z In the formula, a is 0.1-10, b is 0.1-5, z is the number of oxygen atoms satisfying the valence of each metal element, and the content of the copper-zinc component is 1-10% by mass of the amorphous silicon-aluminum catalyst, and in the modified amorphous silicon-aluminum catalyst, 0-valent copper and +1-valent copper account for more than 50% of the total copper content.

17. The modified amorphous silica-alumina catalyst according to claim 16, wherein, The amorphous silica-alumina catalyst has a silica-alumina ratio of 1.8-2.5, the copper-zinc component content is 3-5% by mass of the amorphous silica-alumina catalyst, and in the modified amorphous silica-alumina catalyst, 0-valent copper and +1-valent copper account for more than 70% of the total copper content.

18. The modified amorphous silica-alumina catalyst according to claim 16, wherein, The amorphous silica-alumina catalyst has a pore size of 20-50 nm. And / or, the specific surface area of ​​the amorphous silica-alumina catalyst is less than 250 m². 2 / g; And / or, the XRD pattern of the amorphous silica-alumina catalyst has only one diffuse diffraction peak at 25° to 27°.

19. The application of the modified amorphous silica-alumina catalyst obtained by the preparation method according to any one of claims 1-15, or the modified amorphous silica-alumina catalyst according to any one of claims 16-18, in C4 superposition.

20. The application according to claim 19, wherein, The application of the modified amorphous silica-alumina catalyst in C4 superconducting raw materials with an alkaline nitrogen content of 0-30 ppm.

21. A method for carbon-4 superposition, characterized in that, The method includes: contacting a mixed C4 catalyst with a superimposed catalyst under superimposed reaction conditions, wherein the superimposed catalyst is a modified amorphous silica-alumina catalyst obtained by the preparation method according to any one of claims 1-15, or a modified amorphous silica-alumina catalyst according to any one of claims 16-18.

22. The method according to claim 21, wherein, The basic nitrogen content of the mixed C4 is 0-30 ppm.

23. The method according to claim 21, wherein, The superposition reaction conditions include: a temperature of 160-220℃, a pressure of 2-6 MPa, and a space velocity of 0.1-2 h⁻¹. -1 .

24. The method according to claim 21, wherein, The C4 stacking was carried out in a fixed-bed reactor.

25. The method according to claim 24, wherein, The fixed-bed reactor is a downflow fixed-bed reactor.

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