Catalysts for hydrogenation dealkylation to benzene, their preparation methods and applications, and methods for catalytic hydrogenation dealkylation of heavy aromatics to benzene.

Abstract

This invention relates to the field of aromatic hydrocarbon catalytic conversion, and discloses a catalyst for the hydrogenation dealkylation of heavy aromatic hydrocarbons to benzene, its preparation method, and its application. The method for the catalytic hydrogenation dealkylation of heavy aromatic hydrocarbons to benzene includes a catalyst comprising a composite support and an active metal component. The composite support comprises alumina, a first modifying component, and a second modifying component. The first modifying component is phosphorus, and the second modifying component is selected from at least one of alkali metals, alkaline earth metals, and rare earth metals. The active metal component is a transition metal. The total acidity of the catalyst does not exceed 60 μmol NH3 / g. The catalyst provided by this invention exhibits high catalytic activity for the hydrogenation dealkylation of heavy aromatic hydrocarbons, low total acidity, and good stability.

Description

Technical Field

[0001] This invention relates to the field of aromatic hydrocarbon catalytic conversion, specifically to a hydrogenation dealkylation catalyst for benzene production, its preparation method and application, and a method for catalytic hydrogenation dealkylation of heavy aromatic hydrocarbons to benzene. Background Technology

[0002] In recent years, the increasing operating rates and new production capacity of styrene, phenol, and caprolactam plants both domestically and internationally have led to a surge in demand for benzene and a continuous rise in its market price. Furthermore, increasingly stringent environmental regulations in various regions have increased the difficulty and cost of benzene transportation, exacerbating localized benzene shortages. This market environment has made efficient benzene production technologies increasingly popular among enterprises. Aromatic catalytic hydrogenation dealkylation technology utilizes the hydrogenation dealkylation reaction of aromatic side chains to selectively convert alkyl aromatics into benzene. Alternatively, by simply controlling the reaction temperature, it can directly convert alkyl aromatics to benzene through deep dealkylation, or selectively dealkylate alkyl aromatics to benzene, toluene, and xylene.

[0003] Currently, the catalysts used in the catalytic hydrogenation dealkylation of aromatics to produce benzene are composite oxides, which can effectively remove substituents from the side chains of alkyl aromatics to produce benzene. UOP's Hydeal aromatic dealkylation process uses a composite oxide catalyst, which can dealkylate toluene and higher aromatics (C7+) at operating temperatures of 600-650℃. + A) Conversion to benzene. Lummus's aromatic dealkylation technology uses chromium-aluminum catalysts, with the Detol process for toluene to benzene, the Litol process for light oil to benzene, and the Pyrotol process for cracked gasoline to benzene, all at reaction temperatures of 600-650℃. CN1107077A discloses a rare earth C9-C... 10 Aromatic dealkylation catalysts and their preparation methods, using C9-C 10 Using aromatics as raw materials and rare earth metal-modified Cr2O3 / Al2O3 as catalyst, the selectivity for (benzene + toluene + xylene) can reach 95%. This catalyst is also suitable for the catalytic dealkylation of toluene to produce benzene.

[0004] However, due to the high operating temperature and numerous side reactions of the aromatic catalytic hydrogenation dealkylation to benzene technology, the unit has high hydrogen consumption and low utilization rate of by-products. Summary of the Invention

[0005] The purpose of this invention is to overcome the limitations of existing technologies in the catalytic hydrogenation of heavy aromatics to benzene, where C2... + The deep cracking of light hydrocarbons leads to increased hydrogen consumption and low utilization and added value of gaseous products. This paper provides a catalyst for the hydrogenation dealkylation of heavy aromatics to produce benzene, its preparation method and application, and a method for the catalytic hydrogenation dealkylation of heavy aromatics to produce benzene. The catalyst has high catalytic activity and good product selectivity.

[0006] To achieve the above objectives, a first aspect of the present invention provides a catalyst for the hydrogenation dealkylation to benzene production, the catalyst comprising a composite support and an active metal component;

[0007] The composite carrier comprises alumina, a first modifying component, and a second modifying component; the first modifying component is phosphorus, and the second modifying component is selected from at least one of alkali metals, alkaline earth metals, and rare earth metals; the active metal component is a transition metal.

[0008] The total acid content of the catalyst does not exceed 60 μmol NH3 / g.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned hydrogenation dealkylation catalyst for benzene production, comprising the following steps:

[0010] (1) Alumina and / or its precursor, a first modified component source, a second modified component source and optional molding aids are mixed, shaped and then subjected to a first calcination to obtain a carrier precursor;

[0011] (2) The carrier precursor is heat-treated in the presence of water vapor to obtain a composite carrier;

[0012] (3) The composite carrier is brought into contact with a solution of a soluble compound containing an active metal component, and then dried and calcined a second time.

[0013] The third aspect of this invention provides the application of the above-mentioned hydrogenation dealkylation catalyst for benzene production in the catalytic hydrogenation dealkylation of heavy aromatics.

[0014] A fourth aspect of the present invention provides a method for the catalytic hydrogenation and dealkylation of heavy aromatics to produce benzene, the method comprising:

[0015] (1) The heavy aromatic hydrocarbon and the first hydrogen stream are contacted with the first catalyst to carry out the first dealkylation reaction, and the first gas phase product and the intermediate liquid phase product are obtained.

[0016] (2) The intermediate liquid phase product and the second hydrogen gas stream are contacted with the second catalyst to carry out the second dealkylation reaction, and the second gas phase product and the benzene-rich liquid phase product are obtained.

[0017] The first catalyst comprises a zeolite molecular sieve; the zeolite molecular sieve has a ten-membered ring channel structure and / or a twelve-membered ring channel structure.

[0018] The second catalyst is the hydrogenation dealkylation catalyst for benzene production provided in the first aspect.

[0019] The inventors of this invention discovered during their research that in the catalytic hydrogenation dealkylation reaction of heavy aromatics to produce benzene, the methyl group undergoes a hydrogenation removal reaction to generate methane, C2 +The side chain substituents will undergo hydrogenation removal reactions to produce C2 hydrocarbons such as ethane and propane. + Light hydrocarbons, this part is C2 + Light hydrocarbons are excellent feedstocks for ethylene cracking, with a higher added value than methane. High temperatures can lead to the formation of C2 during dealkylation. + Light hydrocarbons will undergo further deep cracking to produce methane, which not only increases the plant's hydrogen consumption but also results in low utilization of byproducts.

[0020] The hydrogenation dealkylation catalyst for benzene production provided by this invention exhibits high catalytic activity for the hydrogenation dealkylation of heavy aromatics, low total acidity, and good stability. The method for catalytic hydrogenation dealkylation of heavy aromatics to benzene provided by this invention utilizes a catalyst gradation and stepwise dealkylation strategy to first dealkylate C2... + The side chain is removed and separated, and then the remaining alkyl group on the benzene ring is further removed. The inventors of this invention have discovered that using the above-mentioned hydrogenation dealkylation catalyst for benzene production in combination with the first catalyst results in a combined reaction system with superior heavy aromatic catalytic hydrogenation dealkylation performance, which can solve the C2 problem in the traditional heavy aromatic catalytic hydrogenation to benzene process. + The deep cracking of gaseous light hydrocarbons can solve the problem of increasing the added value of gaseous products, reducing hydrogen consumption of the unit, and further improving the economic efficiency of the unit. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a heavy aromatic hydrocarbon hydrogenation dealkylation apparatus for producing benzene according to one embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures

[0023] 1 Heavy Aromatics 2-1 First Hydrogen Stream

[0024] 2-2 Second hydrogen stream 3 First dealkylation reaction product

[0025] 4 First gas phase product 5 Intermediate liquid phase product

[0026] 6. Second dealkylation reaction product; 7. Second gas-phase product.

[0027] 8. Benzene-rich liquid phase product I: First aromatic catalytic hydrogenation dealkylation reactor

[0028] II. First gas-liquid separation unit; III. Second aromatic catalytic hydrodealkylation reactor.

[0029] IV. Second Gas-Liquid Separation Unit Detailed Implementation

[0030] 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.

[0031] The first aspect of this invention provides a catalyst for the hydrogenation dealkylation to benzene production, the catalyst comprising a composite support and an active metal component;

[0032] The composite carrier comprises alumina, a first modifying component, and a second modifying component; the first modifying component is phosphorus, and the second modifying component is selected from at least one of alkali metals, alkaline earth metals, and rare earth metals; the active metal component is a transition metal.

[0033] The total acid content of the catalyst does not exceed 60 μmol NH3 / g.

[0034] According to the present invention, preferably, the catalyst has a pore volume of 0.55-0.85 cm³. 3 / g, preferably 0.65-0.84cm 3 / g.

[0035] According to the present invention, the total acid content in the catalyst needs to be controlled at a low level. If the total acid content is too high, it is not conducive to improving the stability of the catalyst. Preferably, the total acid content of the catalyst does not exceed 15 μmol NH3 / g, and more preferably 5-10 μmol NH3 / g.

[0036] According to the present invention, preferably, the ratio of the amount of weak acid to the amount of strong acid in the catalyst is 5-10:1, more preferably 6-10:1. In the above-mentioned preferred embodiment, it is beneficial to reduce the surface carbon area of ​​the dealkylation catalyst and improve the stability of the catalyst.

[0037] In this invention, the acid content is characterized by the following method: ammonia gas temperature-programmed desorption is used for determination. The testing instrument is the AutoChem2920 fully automatic temperature-programmed chemisorption analyzer from Micrometrics. The testing temperature is 120-650℃. The amount of NH3 desorbed between these desorption temperatures is recorded as the total acid content. Among them, weak acid is the amount of NH3 desorbed before the desorption temperature is 300℃, and strong acid is the amount of NH3 desorbed between the desorption temperature is 300℃-600℃.

[0038] In this invention, the pore volume is characterized by a low-temperature nitrogen adsorption method, using a Micromeritics 3Flex-Physisorption fully automated specific surface area and pore size distribution analyzer.

[0039] In this invention, preferably, based on the total amount of the catalyst, the content of the composite support is 70-99.99 wt%, more preferably 85-99.97 wt%, and the content of the active metal component is 0.01-30 wt%, more preferably 0.03-15 wt%.

[0040] Preferably, when the active metal component is a noble metal, the content of the active metal component is 0.03-1 wt% based on the total amount of the catalyst and calculated by element.

[0041] Preferably, when the active metal component is a non-precious metal, the content of the active metal component is 5-15 wt% based on the total amount of the catalyst and in terms of elemental composition.

[0042] It is understood that the sum of the contents of all components in the catalyst is 100% by weight.

[0043] In this invention, preferably, based on the total amount of the composite carrier, the content of alumina is 80-99.99 wt%, more preferably 95-99.5 wt%; and based on oxides, the total content of the first modified component and the second modified component is 0.01-20 wt%, more preferably 0.5-5 wt%.

[0044] In this invention, the sum of the contents of each component in the composite carrier satisfies 100% by weight.

[0045] In this invention, preferably, the mass ratio of the first modified component to the second modified component, based on oxides, is 0.5-5:1, more preferably 1-1.5:1. Under these preferred conditions, the synergistic effect of the first and second modified components can be further enhanced, which is beneficial to improving the overall stability of the catalyst.

[0046] In this invention, the content of each component is determined by XRF.

[0047] In this invention, preferably, the active metal component is selected from at least one of Ni, Cr, Pt, Co, Rh, Mn and Mo, and more preferably from at least one of Pt, Cr and Ni.

[0048] Preferably, the second modifying component is selected from at least one of Na, K, Mg, Ca, Ba, Ce, and La, more preferably at least one of K, Mg, and La, and even more preferably at least two of K, Mg, and La. For example, the second modifying component can be K and Mg, K and La, Mg and La, or K, Mg, and La, more preferably K and Mg, K and La, or K, Mg, and La. Using the above-mentioned preferred second modifying component is beneficial to improving the catalytic activity of the catalyst and reducing the total acidity of the catalyst.

[0049] A second aspect of the present invention provides a method for preparing the above-mentioned hydrogenation dealkylation catalyst for benzene production, comprising the following steps:

[0050] (1) Alumina and / or its precursor, a first modified component source, a second modified component source and optional molding aids are mixed, shaped and then subjected to a first calcination to obtain a carrier precursor;

[0051] (2) The carrier precursor is heat-treated in the presence of water vapor to obtain a composite carrier;

[0052] (3) The composite carrier is brought into contact with a solution of a soluble compound containing an active metal component, and then dried and calcined a second time.

[0053] In this invention, the precursor of alumina refers to a substance that can be calcined to obtain alumina, which is well known to those skilled in the art.

[0054] In this invention, the selection range of the crystal form of the alumina is relatively wide. Preferably, the alumina is selected from at least one of γ-Al2O3, β-Al2O3 and α-Al2O3, and more preferably γ-Al2O3.

[0055] In this invention, the first and second modified component sources can be selected from any substances that can provide the first and second modified components, and there are no special limitations on this. The selection range of the first and second modified components is the same as that in the above-described hydrogenation dealkylation catalyst for benzene production, and will not be repeated here.

[0056] Preferably, the source of the first modified component is selected from phosphoric acid and / or ammonium hydrogen phosphate.

[0057] Preferably, the source of the second modified component is a soluble salt containing the second modified component, preferably a nitrate and / or an acetate.

[0058] In this invention, preferably, the amount of alumina and / or its precursor, the first modified component source, and the first modified component source is such that the content of alumina in the obtained composite carrier is 80-99.99 wt%, preferably 95-99.5 wt%; and the total content of the first modified component and the second modified component, calculated as oxides, is 0.01-20 wt%, preferably 0.5-5 wt%.

[0059] And / or, based on oxides, the mass ratio of the first modified component source to the second modified component source is 0.5-5:1, preferably 1-1.5:1.

[0060] In this invention, there are no special requirements for the molding method; conventional molding methods and conditions in the art can be used. For example, the molding method is extrusion molding.

[0061] Preferably, the molding aid includes a binder and / or an extrusion aid.

[0062] In this invention, there is no particular limitation on the type of adhesive solvent; all adhesive solvents defined in this art are applicable to this invention. Preferably, the adhesive solvent is selected from citric acid and / or nitric acid. In this invention, there is no particular limitation on the amount of adhesive solvent used; it can be reasonably adjusted according to the viscosity and strength requirements of alumina. Preferably, the amount of adhesive solvent used is 1-5 wt% of the weight of the alumina and / or its precursor.

[0063] Preferably, the adhesive solvent is provided in the form of an aqueous solution of the adhesive solvent, the concentration of which is 50-100 wt%.

[0064] In this invention, there is no particular limitation on the type of extrusion aid; any extrusion aid conventionally defined in the art is applicable to this invention. Preferably, the extrusion aid is selected from at least one of guar gum powder, cellulose, and starch. In this invention, there is no particular limitation on the amount of extrusion aid used. Preferably, the amount of extrusion aid used is 1-5 wt% of the weight of the alumina and / or its precursor.

[0065] In this invention, preferably, the conditions for the first calcination include: a calcination temperature of 450-650℃, more preferably 500-550℃, and a calcination time of 1-10h, more preferably 2-5h.

[0066] In this invention, to further improve the effect of heat treatment, preferably, in step (2), the heat treatment conditions include: a temperature of 550-700℃, preferably 550-650℃; and a time of 2-10h, preferably 3-5h. Adopting the above preferred embodiments is beneficial for increasing the catalyst pore volume and improving the conversion rate of the reactants.

[0067] In this invention, preferably, the steam introduction rate is 50-500 mL / h, more preferably 100-200 mL / h, relative to 100 g of carrier precursor. It is understood that the steam introduction rate can increase proportionally as the amount of carrier precursor increases. Excessive steam introduction can easily damage the crystal structure of alumina, while insufficient steam introduction results in poor treatment effect and insufficient catalyst activity.

[0068] In this invention, there are no particular limitations on the specific contact method in step (3), as long as the active metal component can be loaded onto the composite carrier. Preferably, the contact in step (3) includes: impregnating the composite carrier with a solution of a soluble compound containing the active metal component.

[0069] The impregnation can be carried out using conventional operations and conditions in the art. There are no special requirements for the concentration and amount of the solution containing the soluble compound with active metal components, as long as the required amount of active metal can be achieved.

[0070] In this invention, there are no particular limitations on the specific conditions for drying and second calcination in step (3). Preferably, the drying conditions include: a drying temperature of 50-150℃, preferably 90-120℃; and a drying time of 1-10h, preferably 3-6h.

[0071] In this invention, preferably, in step (3), the conditions for the second roasting include: a roasting temperature of 450-750℃, preferably 550-650℃; and a roasting time of 1-10h, preferably 3-6h.

[0072] The third aspect of this invention provides the application of the above-mentioned hydrogenation dealkylation catalyst for benzene production in the catalytic hydrogenation dealkylation of heavy aromatics.

[0073] A fourth aspect of the present invention provides a method for the catalytic hydrogenation and dealkylation of heavy aromatics to produce benzene, the method comprising:

[0074] (1) The heavy aromatic hydrocarbon and the first hydrogen stream are contacted with the first catalyst to carry out the first dealkylation reaction, and the first gas phase product and the intermediate liquid phase product are obtained.

[0075] (2) The intermediate liquid phase product and the second hydrogen gas stream are contacted with the second catalyst to carry out the second dealkylation reaction, and the second gas phase product and the benzene-rich liquid phase product are obtained.

[0076] The first catalyst comprises a zeolite molecular sieve; the zeolite molecular sieve has a ten-membered ring channel structure and / or a twelve-membered ring channel structure.

[0077] The second catalyst is the hydrogenation dealkylation catalyst for benzene production provided in the first aspect.

[0078] In this invention, through a strategy of catalyst gradation and stepwise dealkylation, C2 is first dealkylated... + The side chain is removed and separated, and then the remaining alkyl group on the benzene ring is further removed. The inventors of this invention have discovered that using the above-mentioned hydrogenation dealkylation catalyst for benzene production in combination with the first catalyst results in a combined reaction system with superior heavy aromatic catalytic hydrogenation dealkylation performance, which can solve the C2 problem in the traditional heavy aromatic catalytic hydrogenation to benzene process.+ The deep cracking of gaseous light hydrocarbons can solve the problem of increasing the added value of gaseous products, reducing hydrogen consumption of the unit, and further improving the economic efficiency of the unit.

[0079] According to the present invention, preferably, the zeolite molecules are sieved from at least one of ZSM-5, mordenite, and β-zeolite. The presence of the aforementioned preferred molecular sieves in the first catalyst contributes to increasing C2 content. + Side chain removal efficiency. The above-mentioned zeolite molecular sieves can be obtained by conventional preparation methods or commercially available.

[0080] In this invention, preferably, the method further includes: performing a first gas-liquid separation on the product of the first dealkylation reaction to obtain a first gas-phase product and an intermediate liquid-phase product; and performing a second gas-liquid separation on the product of the second dealkylation reaction to obtain a second gas-phase product and a benzene-rich liquid-phase product. This invention does not have special requirements regarding the specific methods of the first and second gas-liquid separations, and conventional gas-liquid separation methods in the art can be used. For example, a high-precision separator gas-liquid separation can be used.

[0081] According to the present invention, preferably, the content of the zeolite molecular sieve is 50-90 wt%, more preferably 60-80 wt%, based on the total amount of the first catalyst.

[0082] According to the present invention, preferably, the first catalyst further comprises a modified metal and a binder.

[0083] Preferably, based on the total amount of the first catalyst and calculated as oxides, the content of the modified metal is 0.01-10 wt%, more preferably 0.05-5 wt%, and the content of the binder is 9-50 wt%, more preferably 19-40 wt%.

[0084] In this invention, the sum of the contents of each component in the first catalyst is 100%.

[0085] The present invention has a wide range of choices for the modified metal in the first catalyst, and can be various metals with dealkylation activity commonly used in the art. Preferably, the modified metal is selected from at least one of Ni, Mo, Pt and Re.

[0086] In this invention, the range of types of adhesives is wide, and they can be selected from any conventional adhesives in the art. This invention does not have any particular limitation on this. For example, the adhesive can be alumina.

[0087] The present invention does not have any special limitation on the source of the first catalyst mentioned above. It can be prepared by conventional preparation methods or obtained commercially.

[0088] Preferably, the first catalyst can be prepared by the following method: mixing and molding zeolite molecular sieve, modified metal source, binder and molding aid.

[0089] In this invention, the specific type of the modified metal source is not particularly limited, and can be selected from soluble salts of modified metals, preferably at least one of nitrates, sulfates, acetates and chlorides of modified metals.

[0090] This invention does not impose any particular limitations on the mixing and molding methods and conditions, as long as the components can be mixed uniformly and the catalyst has a certain morphology and strength. The selection range of the molding aid can be the same as that in the preparation of the above-mentioned hydrogenation dealkylation to benzene catalyst, and will not be repeated here.

[0091] In this invention, preferably, the conditions for the first dealkylation reaction include: a temperature of 300-500°C and a weight hourly space velocity (WHSV) of 1-10 h⁻¹ for the heavy aromatic hydrocarbons. -1 The hydrogen-to-hydrocarbon molar ratio is 1-10, and the reaction pressure is 1-10 MPa; preferably, the temperature is 300-400℃, and the weight hourly space velocity of the heavy aromatics is 2-5 h⁻¹. -1 The hydrogen-to-hydrogen molar ratio is 2-4, and the reaction pressure is 2-4 MPa. Using the above-mentioned preferred embodiment is beneficial for C2… + The side chains are effectively removed without causing damage to the C2 after removal. + Deep cleavage of side chains.

[0092] Preferably, the conditions for the second dealkylation reaction include: a temperature of 500-800°C and a weight hourly space velocity (WHSV) of 0.5-5 h⁻¹ for the intermediate liquid phase stream. -1 The hydrogen-to-hydrocarbon molar ratio is 1-10, and the reaction pressure is 1-10 MPa; preferably, the temperature is 550-700℃, and the weight hourly space velocity (WHSV) of the intermediate liquid phase is 1-2 h⁻¹. -1 The hydrogen-to-hydrogen molar ratio is 3-6, and the reaction pressure is 3-5 MPa.

[0093] In this invention, preferably, the heavy aromatic hydrocarbon is C9. + Aromatic hydrocarbons, preferably C2 in the heavy aromatic hydrocarbons + The side chain content is 15wt%-45wt%.

[0094] Preferably, the intermediate liquid phase product contains C2 + The side chain content is no more than 5 wt%, preferably no more than 2 wt%. Under these preferred conditions, C2 can be avoided. + The side chain enters the second stage of deep dealkylation and cracking.

[0095] The method for producing benzene by catalytic hydrogenation dealkylation of heavy aromatics according to the present invention can be carried out using conventional equipment or systems in the art. According to a preferred embodiment of the present invention, the method is carried out using, for example... Figure 1 The stepwise hydrodealkylation process is carried out in the apparatus shown.

[0096] The apparatus comprises a first aromatic catalytic hydrodealkylation reactor I, a first gas-liquid separation device II, a second aromatic catalytic hydrodealkylation reactor III, and a second gas-liquid separation device IV, which are connected in sequence.

[0097] The first aromatic catalytic hydrogenation dealkylation reactor I and the second aromatic catalytic hydrogenation dealkylation reactor III are respectively filled with a first catalyst and a second catalyst.

[0098] The first aromatic catalytic hydrodealkylation reactor I is used to carry out a first dealkylation reaction on heavy aromatic 1 and the first hydrogen stream 2-1 to obtain the first dealkylation reaction product 3.

[0099] The first gas-liquid separation device II is used to separate the first dealkylation reaction product 3 from the first aromatic catalytic hydrodealkylation reactor I into a first gas phase product 4 and an intermediate liquid phase product 5.

[0100] The second aromatic catalytic hydrodealkylation reactor III is used to carry out a second dealkylation reaction between the intermediate liquid product 5 from the first gas-liquid separation unit II and the second hydrogen stream 2-2 to obtain the second dealkylation reaction product 6.

[0101] The second gas-liquid separation device IV is used to separate the second dealkylation reaction product 6 from the second aromatic catalytic hydrodealkylation reactor III into a second gas phase product 7 and a benzene-rich liquid phase product 8.

[0102] The present invention will be described in detail below through embodiments.

[0103] The raw materials used in the following preparation examples and embodiments were commercially available and of analytical grade (AR).

[0104] The following preparation examples illustrate the preparation of the hydrogenation dealkylation catalyst for benzene production in this invention.

[0105] Preparation Example 1-1

[0106] (1) Take 100g of γ-Al2O3·H2O, then add 4g of 65wt% dilute nitric acid, 1g of guar gum powder and appropriate amounts of magnesium nitrate, potassium acetate and phosphoric acid. After mixing thoroughly, extrude into strips and calcine at 550℃ for 5h to obtain the carrier precursor.

[0107] (2) 100g of the above-mentioned carrier precursor was treated with steam at 650℃ for 5h, with a steam introduction rate of 200mL / min, to obtain a composite carrier. The composite carrier contained 3.5wt% MgO, 1wt% K2O and 5wt% P2O5, respectively, with the remainder being alumina. The mass ratio of the first modified component to the second modified component was 1.1:1, based on oxides.

[0108] (3) A certain amount of chromium nitrate was dissolved in water and impregnated on the surface of the composite support. The solution was dried at 120°C for 4 hours and calcined at 650°C for 3 hours to obtain a hydrogenation dealkylation catalyst for benzene production, designated as B1. The content of the composite support in the catalyst was 85 wt% and the content of Cr2O3 was 15 wt%.

[0109] The physicochemical data of catalyst B1 are shown in Table 1.

[0110] Preparation Examples 1-2

[0111] (1) Take 100g of γ-Al2O3·H2O, then add 4g of 65wt% dilute nitric acid, 1g of guar gum powder and appropriate amounts of lanthanum nitrate, potassium acetate and ammonium hydrogen phosphate. After mixing thoroughly, extrude into strips and calcine at 500℃ for 2h to obtain the carrier precursor.

[0112] (2) 100g of the above-mentioned carrier precursor was treated with steam at 550℃ for 10h, with a steam introduction rate of 100mL / min, to obtain a composite carrier. The contents of La2O3, K2O, and P2O5 in the composite carrier were 2.5wt%, 2.5wt%, and 5wt%, respectively, with the remainder being alumina. The mass ratio of the first modified component to the second modified component was 1:1, based on oxides.

[0113] (3) A certain amount of chloroplatinic acid was dissolved in water and impregnated on the surface of the composite support. The mixture was dried at 90°C for 6 hours and calcined at 550°C for 6 hours to obtain a hydrogenation dealkylation catalyst for benzene production, designated as B2. The content of the composite support in the catalyst was 99.95 wt%, and the content of platinum oxide was 0.05 wt%.

[0114] The physicochemical data of catalyst B2 are shown in Table 1.

[0115] Preparation Examples 1-3

[0116] (1) Take 100g of γ-Al2O3·H2O, then add 4g of 65wt% dilute nitric acid, 1g of guar gum powder and appropriate amounts of lanthanum nitrate, magnesium acetate and ammonium hydrogen phosphate. After mixing thoroughly, extrude into strips and calcine at 500℃ for 5h to obtain the carrier precursor.

[0117] (2) 100g of the above-mentioned carrier precursor was treated with steam at 600℃ for 10h, with a steam introduction rate of 150mL / min, to obtain a composite carrier. The contents of La2O3, MgO, and P2O5 in the composite carrier were 3.5wt%, 3.5wt%, and 4.7wt%, respectively, with the remainder being alumina. The mass ratio of the first modified component to the second modified component, based on oxides, was 1.49:1.

[0118] (3) A certain amount of nickel nitrate was dissolved in water and impregnated on the surface of the composite support. The solution was dried at 120°C for 2 hours and calcined at 600°C for 5 hours to obtain a hydrogenation dealkylation catalyst for benzene production, designated as B3. The composite support content in the catalyst was 93 wt% and the nickel oxide content was 7 wt%.

[0119] The physicochemical data of catalyst B3 are shown in Table 1.

[0120] Preparation Examples 1-4

[0121] The method is the same as in Preparation Example 1, except that the second modified component is Mg, and the contents of MgO and P2O5 in the composite carrier are 4.5 wt% and 5 wt%, respectively.

[0122] A hydrogenation dealkylation catalyst for benzene production was prepared, designated B4. The physicochemical data of catalyst B4 are shown in Table 1.

[0123] Preparation Examples 1-5

[0124] The method is the same as in Preparation Example 1, except that the amounts of magnesium nitrate, potassium acetate, and phosphoric acid are adjusted such that the contents of MgO, K2O, and P2O5 in the composite carrier are 2.5 wt%, 0.85 wt%, and 5 wt%, respectively, and the mass ratio of the first modified component to the second modified component, based on oxides, is 0.67:1.

[0125] A hydrogenation dealkylation catalyst for benzene production was prepared, designated B5. The physicochemical data of catalyst B5 are shown in Table 1.

[0126] Preparation Examples 1-6

[0127] The method is the same as in Preparation Example 1, except that the amounts of magnesium nitrate, potassium acetate, and phosphoric acid are adjusted such that the contents of MgO, K2O, and P2O5 in the composite carrier are 1.6 wt%, 2.4 wt%, and 1 wt%, respectively, and the mass ratio of the first modified component to the second modified component is 4:1 based on oxides.

[0128] A hydrogenation dealkylation catalyst for benzene production was prepared, designated B6. The physicochemical data of catalyst B6 are shown in Table 1.

[0129] Comparative Preparation Example 1

[0130] Following the method in Preparation Example 1, except that the water vapor in the heat treatment process was replaced with an equal amount of air, a hydrogenation dealkylation catalyst for benzene production, designated DB1, was obtained.

[0131] The physicochemical data of catalyst DB1 are shown in Table 1.

[0132] Comparative Preparation Example 2

[0133] The method is the same as in Preparation Example 1, except that the composite carrier does not contain a second modifying component, and the content of P2O5 in the composite carrier is 5 wt%.

[0134] A hydrogenation dealkylation catalyst for benzene production was prepared, designated DB2. The physicochemical data of catalyst DB2 are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] The following preparation examples illustrate the preparation of the first catalyst in this invention.

[0139] Preparation Example 2-1

[0140] Take 75g of β-zeolite (silicon oxide / alumina = 35), 25g of γ-Al2O3·H2O, mix them evenly, then add 4g of 65wt% dilute nitric acid, 1g of guar gum powder and an appropriate amount of ammonium perrhenate, mix thoroughly, extrude into strips, and calcine at 550℃ for 5h to obtain the first catalyst, numbered A1. The Re2O3 content in the catalyst is 1.5wt%.

[0141] Preparation Example 2-2

[0142] Take 75g of ZSM-5 zeolite (silicon oxide / alumina = 25), 40g of γ-Al2O3·H2O, mix them evenly, then add 6g of 65wt% dilute nitric acid, 3g of guar gum powder and an appropriate amount of ammonium molybdate, mix thoroughly, extrude into strips, and calcine at 550℃ for 5h to obtain the first catalyst, numbered A2. The content of MoO3 in the catalyst is 5wt%.

[0143] Preparation Examples 2-3

[0144] Take 75g of mordenite (silica / alumina = 30), 30g of γ-Al2O3·H2O, mix them evenly, then add 3g of 65wt% dilute nitric acid, 2g of guar gum powder and an appropriate amount of chloroplatinic acid, mix thoroughly, extrude into strips, and calcine at 550℃ for 5h to obtain the first catalyst, numbered A3. The PtO2 content in the catalyst is 0.05wt%.

[0145] Example 1

[0146] Adopting such Figure 1 The apparatus shown is for the hydrogenation and dealkylation of heavy aromatics to produce benzene. It utilizes C9... + Heavy aromatics are C9-C 10 Aromatic hydrocarbons, of which C2 + The side chain content is 35 wt%.

[0147] 3g of catalyst A1 was used as the first catalyst and packed into the first aromatic catalytic hydrodealkylation reactor I, and 4.5g of catalyst B1 was used as the second catalyst and packed into the second aromatic catalytic hydrodealkylation reactor III. The conditions for the first dealkylation reaction included: pressure controlled at 3MPa and temperature controlled at 380℃; the conditions for the second dealkylation reaction included: pressure controlled at 4MPa and temperature controlled at 680℃.

[0148] After the apparatus stabilizes, C92 is introduced from the first aromatic catalytic hydrodealkylation reactor I. + Heavy aromatics 1 and the first hydrogen stream 2-1 result in a weight hourly space velocity (WHSV) of 3 h⁻¹ for the heavy aromatics in the first aromatics catalytic hydrodealkylation reactor I. -1 The amount of the first hydrogen stream used results in a hydrogen-to-hydrocarbon molar ratio of 3 in the first aromatic catalytic hydrodealkylation reactor I; C9 + Heavy aromatic hydrocarbons, a first hydrogen stream, and a first catalyst are contacted to carry out a first dealkylation reaction. The resulting product is then separated into a first gas phase product 4 and an intermediate liquid phase product 5 by a first gas-liquid separation unit II.

[0149] Intermediate liquid product 5 and second hydrogen stream 2-2 are introduced into the second aromatic catalytic hydrodealkylation reactor III, where they contact the second catalyst to carry out the second dealkylation reaction. The weight hourly space velocity (WHSV) of the intermediate liquid product is 2 h⁻¹. -1 The amount of the second hydrogen stream ensures a hydrogen-to-hydrocarbon molar ratio of 4.5 in the second aromatic catalytic hydrodealkylation reactor III. The resulting product undergoes gas-liquid separation in the second gas-liquid separator IV to obtain a second gaseous product 7 and a benzene-rich liquid product 8.

[0150] After 12 hours of reaction, the product was collected and analyzed. The results are shown in Table 2.

[0151] Examples 2-8 and Comparative Examples 1-3 were loaded according to the combinations and conditions in Table 2 and Table 2 (continued), and the reaction of heavy aromatic hydrocarbons to benzene by hydrogenation and dealkylation was carried out. The reaction results are shown in Table 2 and Table 2 (continued).

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158] Table 2

[0159]

[0160]

[0161] Continued from Table 2

[0162]

[0163]

[0164] Combining the results in Table 2 and Table 2 (continued), it can be seen from Example 8 that the hydrogenation dealkylation catalyst of the present invention has a low acid content and can efficiently catalyze C9. + The hydrogenation and dealkylation of heavy aromatics to produce benzene; further, through catalyst gradation, the C2 oxidation process in the traditional catalytic hydrogenation of heavy aromatics to produce benzene can be resolved. + The deep cracking of gaseous light hydrocarbons (with low methane content in the second gaseous product) can improve the conversion rate of reactants and the selectivity of benzene, reduce hydrogen consumption of the unit, and further improve the economic efficiency of the unit.

[0165] 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 catalyst for the hydrogenation dealkylation to benzene production, characterized in that, The catalyst comprises a composite support and an active metal component; based on the total amount of the catalyst, the content of the composite support is 70-99.99 wt%, and the content of the active metal component, calculated as oxides, is 0.01-30 wt%. The composite carrier comprises alumina, a first modifying component, and a second modifying component; the first modifying component is phosphorus, and the second modifying component is selected from at least one of alkali metals, alkaline earth metals, and rare earth metals; the active metal component is selected from at least one of Ni, Cr, Pt, Co, Rh, Mn, and Mo; based on the total amount of the composite carrier, the alumina content is 80-99.99 wt%, and the total content of the first modifying component and the second modifying component, calculated as oxides, is 0.01-20 wt%. The catalyst has a pore volume of 0.55-0.85 cm³. 3 / g; The total acid content of the catalyst is determined by ammonia temperature-programmed desorption. The total acid content of the catalyst does not exceed 15 μmol NH3 / g, and the ratio of weak acid content to strong acid content is 6-10:

1. The weak acid content is the amount of NH3 desorbed at a desorption temperature below 300℃, and the strong acid content is the amount of NH3 desorbed at a desorption temperature between 300℃ and 600℃.

2. The catalyst according to claim 1, wherein, The total acid content of the catalyst is 5-10 μmol NH3 / g; And / or, based on the total amount of the catalyst, the content of the composite support is 85-99.97 wt%, and the content of the active metal component, calculated as oxide, is 0.03-15 wt%.

3. The catalyst according to claim 1 or 2, wherein, Based on the total amount of the composite carrier, the content of alumina is 95-99.5 wt%; and based on oxides, the total content of the first modified component and the second modified component is 0.5-5 wt%.

4. The catalyst according to claim 1 or 2, wherein, Based on oxides, the mass ratio of the first modified component to the second modified component is 0.5-5:

1.

5. The catalyst according to claim 4, wherein, Based on oxides, the mass ratio of the first modified component to the second modified component is 1-1.5:

1.

6. The catalyst according to claim 1 or 2, wherein, The active metal component is selected from at least one of Pt, Cr and Ni.

7. The catalyst according to claim 1 or 2, wherein, The second modified component is selected from at least one of Na, K, Mg, Ca, Ba, Ce and La.

8. The catalyst according to claim 7, wherein, The second modifying component is selected from at least one of K, Mg and La.

9. The catalyst according to claim 8, wherein, The second modifying component is selected from at least two of K, Mg and La.

10. The method for preparing the hydrogenation dealkylation catalyst for benzene production according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Alumina and / or its precursor, a first modified component source, a second modified component source and optional molding aids are mixed, shaped and then subjected to a first calcination to obtain a carrier precursor; (2) The carrier precursor is heat-treated in the presence of water vapor to obtain a composite carrier; (3) The composite carrier is brought into contact with a solution of a soluble compound containing an active metal component, and then dried and calcined a second time.

11. The preparation method according to claim 10, wherein, The alumina is selected from at least one of γ-Al2O3, β-Al2O3 and α-Al2O3; And / or, the source of the first modifying component is selected from phosphoric acid and / or ammonium hydrogen phosphate; And / or, the source of the second modified component is a soluble salt containing the second modified component.

12. The preparation method according to claim 11, wherein, The alumina is γ-Al₂O₃; And / or, the source of the second modifying component is a nitrate and / or acetate containing the second modifying component.

13. The preparation method according to any one of claims 10-12, wherein, The conditions for the first roasting include: a roasting temperature of 450-650℃ and a roasting time of 1-10h; And / or, in step (2), the conditions for the heat treatment include: a temperature of 550-700℃ and a time of 2-10h; And / or, relative to 100g of carrier precursor, the water vapor introduction rate is 50-500mL / h; And / or, in step (3), the drying conditions include: a drying temperature of 50-150℃ and a drying time of 1-10h; And / or, in step (3), the conditions for the second calcination include: a calcination temperature of 450-750℃ and a calcination time of 1-10h.

14. The preparation method according to claim 13, wherein, In step (2), the heat treatment conditions include: a temperature of 550-650℃ and a time of 3-5 hours; And / or, relative to 100g of carrier precursor, the water vapor introduction rate is 100-200mL / h.

15. The preparation method according to any one of claims 10-12, wherein, The contact described in step (3) includes impregnating the composite carrier with a solution of a soluble compound containing an active metal component.

16. The preparation method according to claim 15, wherein, The soaking time is 1-24 hours.

17. The application of the hydrogenation dealkylation catalyst according to any one of claims 1-9 in the catalytic hydrogenation dealkylation of heavy aromatics to benzene.

18. A method for the catalytic hydrogenation and dealkylation of heavy aromatics to produce benzene, characterized in that, The method includes: (1) The heavy aromatic hydrocarbon and the first hydrogen stream are contacted with the first catalyst to carry out the first dealkylation reaction, and the first gas phase product and the intermediate liquid phase product are obtained. (2) The intermediate liquid phase product and the second hydrogen gas stream are contacted with the second catalyst to carry out the second dealkylation reaction, and the second gas phase product and the benzene-rich liquid phase product are obtained. The first catalyst comprises a zeolite molecular sieve; the zeolite molecular sieve has a ten-membered ring channel structure and / or a twelve-membered ring channel structure. The second catalyst is the hydrogenation dealkylation catalyst for benzene production according to any one of claims 1-9.

19. The method according to claim 18, wherein, The zeolite molecules are selected from at least one of ZSM-5, mordenite, and β-zeolite.

20. The method according to claim 18 or 19, wherein, Based on the total amount of the first catalyst, the content of the zeolite molecular sieve is 50-90 wt%.

21. The method according to claim 20, wherein, Based on the total amount of the first catalyst, the content of the zeolite molecular sieve is 60-80 wt%.

22. The method according to claim 18 or 19, wherein, The first catalyst also contains a modified metal and a binder.

23. The method according to claim 22, wherein, Based on the total amount of the first catalyst, the content of the modified metal, calculated as oxides, is 0.01-10% by weight, and the content of the binder is 9-50% by weight. And / or, the modified metal is selected from at least one of Ni, Mo, Pt and Re.

24. The method according to claim 18 or 19, wherein, The conditions for the first dealkylation reaction include: a temperature of 300-500℃ and a weight hourly space velocity (WHSV) of 1-10 h⁻¹ for the heavy aromatic hydrocarbons. -1 The hydrogen-to-hydrogen molar ratio is 1-10, and the reaction pressure is 1-10 MPa.

25. The method according to claim 24, wherein, The conditions for the first dealkylation reaction include: a temperature of 300-400℃ and a weight hourly space velocity (WHSV) of 2-5 h⁻¹ for the heavy aromatic hydrocarbons. -1 The hydrogen-to-hydrogen molar ratio is 2-4, and the reaction pressure is 2-4 MPa.

26. The method according to claim 18 or 19, wherein, The conditions for the second dealkylation reaction include: a temperature of 500-800°C and a weight hourly space velocity (WHSV) of 0.5-5 h⁻¹ for the intermediate liquid phase stream. -1 The hydrogen-to-hydrogen molar ratio is 1-10, and the reaction pressure is 1-10 MPa.

27. The method according to claim 26, wherein, The conditions for the second dealkylation reaction include: a temperature of 550-650°C and a weight hourly space velocity (WHSV) of 1-2 h⁻¹ for the intermediate liquid phase stream. -1 The molar ratio of hydrogen to hydrocarbon is 3-6, and the reaction pressure is 3-5 MPa.

28. The method according to any one of claim 18 or 19, wherein, The heavy aromatic hydrocarbon is C9. + Aromatic hydrocarbons.

29. The method according to claim 28, wherein, C2 in the heavy aromatics + The side chain content is 15wt%-45wt%.

30. The method according to any one of claim 18 or 19, wherein, C2 in the intermediate liquid phase product + The content of side chains is not higher than 5 wt%.

31. The method according to claim 30, wherein, C2 in the intermediate liquid phase product + The content of side chains is not higher than 2 wt%.

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