Method for reducing deep cracking of C2 + side chain in hydrodealkylation reaction of alkyl aromatic hydrocarbon

Abstract

The invention discloses a method for reducing deep cracking of a C2 + side chain in a hydrodealkylation reaction of alkyl aromatic hydrocarbon. The method comprises a step of contacting an alkyl aromatic hydrocarbon raw material with an aromatic hydrocarbon catalytic hydrodealkylation catalyst in the presence of hydrogen, and a polar compound and a gas oxidant are added into a reaction system. The method provided by the invention improves the BTX selectivity of the product, solves the problem of deep cracking of C2 + gas-phase light hydrocarbon in the traditional technical process of preparing benzene by catalytic hydrogenation of heavy aromatics, improves the additional value of the gas-phase product, reduces the hydrogen consumption of the device, improves the operation stability of the catalyst, and further improves the economic benefit of the device.

Description

Technical Field

[0001] The present invention relates to the field of catalytic conversion of aromatic hydrocarbons, and more specifically to a method for reducing C2 + Method for deep side chain cleavage. Background Art

[0002] Catalytic hydrogenation and dealkylation of aromatics is a technology that utilizes the hydrogenation and dealkylation reaction of aromatic side chains to selectively convert alkyl aromatics into benzene. It can also be simply controlled by the reaction temperature to directly convert alkyl aromatics into benzene through deep dealkylation, or to selectively dealkylate alkyl aromatics into benzene, toluene and xylene (BTX).

[0003] At present, there are two main types of catalysts used in the technology of catalytic hydrogenation and dealkylation of aromatics: (1) modified molecular sieves, and (2) composite metal oxides. Among them, the modified molecular sieves have strong ability to remove C2 and above side chain alkyls, and low reaction temperature, but weak demethylation ability. For example, CN113171793A discloses a hydrogenation and dealkylation catalyst and its preparation method, which uses heavy aromatics as raw materials and NiMo modified multi-level pore ZSM-5 molecular sieves as catalysts, and is mainly used to remove side chain alkyls above C2, and the product is mainly xylene.

[0004] The composite oxide catalyst has a strong ability to remove methyl groups and can remove methyl groups and C2 + The side chain substituents can be removed efficiently, but the high reaction activation energy makes the reaction start-up temperature high. For example, UOP's Hydeal aromatics dealkylation process uses a composite oxide catalyst, which can dealkylate toluene and aromatics above (C7 + A) Converted into benzene. Lummus' aromatic dealkylation technology uses chromium-aluminum catalysts, among which the Detol process is used for toluene to produce benzene, the Litol process is used for light oil to produce benzene, and the Pyrotol process is used for cracking gasoline to produce benzene. The reaction temperature is also 600-650°C. CN94118235.5 discloses a rare earth C9-C 10 Aromatic dealkylation catalyst and preparation method thereof, with C9-C 10 Using aromatic hydrocarbons as raw materials and rare earth metal-modified Cr2O3 / Al2O3 as catalyst, the BTX selectivity can reach 95%. This catalyst is also suitable for the catalytic dealkylation of toluene to produce benzene. However, this method only considers the removal of side chains, and does not consider that the removed side chains will be deeply cracked into methane.

[0005] For the catalytic hydrodealkylation of aromatic hydrocarbons catalyzed by composite metal oxides, the methyl group will be hydrodealkylated to generate methane. + The side chain substituents will undergo hydrogenation to generate C2 + Light hydrocarbons, this part C2+ Light hydrocarbons are very good raw materials for ethylene cracking, and their added value is higher than that of methane. However, in the actual reaction process, the catalytic hydrodealkylation of aromatics to produce BTX often leads to the generation of C2 + Light hydrocarbons will further crack deeply to produce methane, which will not only increase the hydrogen consumption of the device and the temperature rise of the catalyst, but also reduce the utilization rate of this part of the gas phase product. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method for reducing the C2 + The method of deep cracking of side chains can improve the selectivity of the product BTX and solve the problem of C2 + The deep cracking problem of gas-phase light hydrocarbons can be solved, the added value of gas-phase products can be increased, the hydrogen consumption of the device can be reduced, the operating stability of the catalyst can be improved, and the economic benefits of the device can be further improved.

[0007] The present invention provides a method for reducing the alkyl aromatic hydrocarbons by hydrodealkylation. + The method for deep cracking of side chains comprises the steps of contacting an alkyl aromatic hydrocarbon feedstock with an aromatic hydrocarbon catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, wherein a polar compound and a gaseous oxidant are added into the reaction system.

[0008] Furthermore, the polar compound is preferably mixed with the alkyl aromatic hydrocarbon feedstock and introduced into the reaction system.

[0009] Furthermore, the gaseous oxidant is preferably mixed with hydrogen and introduced into the reaction system.

[0010] Furthermore, the polar compound is at least one of methanol, water and ethanol.

[0011] Furthermore, the mass ratio of the polar compound to the alkyl aromatic hydrocarbon raw material is (0.05-0.5):1000, preferably (0.1-0.2):1000.

[0012] Furthermore, the alkyl aromatic hydrocarbon is C2 + Side chain substituents (side chain substituents with carbon 2 or more) C9 + Aromatic hydrocarbons (monocyclic aromatic hydrocarbons with more than nine carbon atoms), preferably C2 + The side chain of the single ring C9 / C 10 Aromatics (i.e. C9 aromatics and / or C 10 Aromatic hydrocarbons). The present invention is for + Side chain substituent C9 + The source of aromatic hydrocarbons is not particularly limited, for example, but not limited to, at least one of the products from catalytic reforming, pyrolysis gasoline hydrogenation, hydrocracking, etc.+ Side chain substituent C9 + The mass content of aromatics is more than 95%.

[0013] Furthermore, the gas oxidant is a weak gas oxidant, preferably CO2 and / or N2O.

[0014] Furthermore, the volume ratio of the weak gas oxidant to hydrogen is (0.005-0.1):1000, preferably (0.015-0.05):1000.

[0015] Furthermore, the aromatic hydrocarbon catalytic hydrodealkylation catalyst comprises a carrier hydrotalcite and an active component transition metal oxide. The hydrotalcite is preferably magnesium aluminum hydrotalcite, and the Mg / Al atomic ratio in the magnesium aluminum hydrotalcite is 1-10, preferably 3-5.

[0016] Furthermore, the transition metal oxide in the aromatics catalytic hydrodealkylation catalyst is at least one of chromium oxide, nickel oxide, cobalt oxide, rhodium oxide, platinum oxide and palladium oxide, preferably at least one of chromium oxide, cobalt oxide and rhodium oxide.

[0017] Furthermore, the mass content of the transition metal oxide in the aromatics catalytic hydrodealkylation catalyst is 1% to 30%, preferably 3% to 15%; the mass content of the carrier hydrotalcite is 70% to 99%, preferably 85% to 97%.

[0018] Furthermore, the preparation method of the catalyst for catalytic hydrogenation and dealkylation of aromatic hydrocarbons can be prepared by conventional methods, preferably by mixing and molding magnesium aluminum hydrotalcite, peptizing acid, and a binder, roasting, preparing a carrier, and then impregnating an active metal, drying, and roasting to obtain the catalyst. Wherein, the drying and roasting can be carried out under conventional conditions in the art. The peptizing acid can be selected from dilute nitric acid, and the binder can be selected from at least one of sesbania powder and cellulose. The active metal is impregnated until the loading amount is reached.

[0019] Furthermore, the aromatic hydrocarbon catalytic hydrogenation dealkylation reaction product is subjected to gas-liquid separation to obtain gas phase and liquid phase products respectively.

[0020] Furthermore, the reaction conditions are: the temperature is 500-800°C, the weight space velocity of the alkyl aromatic hydrocarbon feedstock is 0.5-5h -1 , the molar ratio of hydrogen to alkyl aromatics is 1 to 10, and the reaction pressure is 1 to 10 MPa. Preferably, the temperature is 550 to 700°C, and the weight space velocity of the alkyl aromatics feedstock is 1 to 2 h -1 , the molar ratio of hydrogen / alkyl aromatics is 5 to 7, and the reaction pressure is 4 to 6 MPa.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] The catalytic hydrodealkylation reaction system of aromatics includes catalysts, raw materials, etc. and the high reaction temperature in the reaction system, which will lead to C2 + C2 generated by side chain removal + Further deep cracking of light hydrocarbons will not only increase the hydrogen consumption of the unit, but also reduce the utilization rate and added value of gas phase products. + Deep cracking of light hydrocarbons will further increase the temperature rise of the reaction bed and cause irreversible damage to the stability of the catalyst. + The side chain deep cracking method maintains a high BTX product selectivity at a normal reaction temperature, and also solves the problem of C2 + The deep cracking problem of gas-phase light hydrocarbons can be solved, the added value of gas-phase products can be increased, the hydrogen consumption of the device can be reduced, the operating stability of the catalyst can be improved, and the economic benefits of the device can be further improved. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0024] The raw materials used in the specific implementation of the present invention are commercially available and have an analytical purity (AR).

[0025] Example 1

[0026] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 3:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass loading of Cr2O3 is 15% and the mass content of hydrotalcite is 85%.

[0027] Alkyl aromatics feedstocks are derived from catalytic reforming of C2 + C9 / C of the side chain 10 Aromatics, among which C9 aromatics and C 10The mass content of aromatics is 100%. In this example, 5g of aromatic catalytic hydrogenation dealkylation catalyst is installed in an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and the polar compound methanol and the gas oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gas oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.05:1000, and the mass ratio of methanol and alkyl aromatic feedstock is 0.1:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T = 570 ° C, the molar ratio of hydrogen / aromatics is 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0028] Example 2

[0029] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 2:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve cobalt nitrate in water, impregnate the surface of the above carrier, dry at 100°C for 5 hours, and calcine at 600°C for 5 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass content of CoO is 8% and the mass content of hydrotalcite is 92%.

[0030] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and polar compound water and gaseous oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gaseous oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.015:1000, and the mass ratio of water and alkyl aromatic feedstock is 0.2:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=550°C, the molar ratio of hydrogen / aromatics is 7, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 1h -1 , reaction pressure 4.0MPa. The reaction results are shown in Table 1.

[0031] Example 3

[0032] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 4:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. A certain amount of rhodium nitrate is dissolved in water, impregnated on the surface of the above carrier, dried at 120°C for 5 hours, and calcined at 650°C for 5 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass loading of Rh2O3 is 3% and the mass content of hydrotalcite is 97%.

[0033] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and a polar compound ethanol and a gaseous oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gaseous oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O to hydrogen is 0.02:1000, and the mass ratio of ethanol to the alkyl aromatic feedstock is 0.05:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=700°C, the molar ratio of hydrogen / aromatics is 6, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 4.0MPa. The reaction results are shown in Table 1.

[0034] Example 4

[0035] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 3:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate and cobalt nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 5 hours, and calcine at 600°C for 5 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, wherein the mass loading of Cr2O3 is 15%, the mass loading of CoO is 3%, and the mass content of hydrotalcite is 82%.

[0036] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and the polar compound ethanol and the gaseous oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gaseous oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.05:1000, and the mass ratio of ethanol and alkyl aromatic feedstock is 0.1:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=600°C, the molar ratio of hydrogen / aromatics is 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1, reaction pressure 4.0MPa. The reaction results are shown in Table 1.

[0037] Comparative Example 1

[0038] 100g of MgO and Al2O3 were mixed, wherein the atomic ratio of Mg / Al was 3:1, and then 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose were added and mixed thoroughly, extruded into strips, and calcined at 550°C for 5h to prepare a carrier. Chromium nitrate was dissolved in water, impregnated on the surface of the above carrier, dried at 120°C for 4 hours, and calcined at 650°C for 3 hours to obtain an aromatic catalytic hydrogenation dealkylation catalyst, wherein the mass loading of Cr2O3 was 15%, and the mass content of MgO and Al2O3 was 85%.

[0039] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and the polar compound methanol and the gas oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gas oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.05:1000, and the mass ratio of methanol and alkyl aromatic feedstock is 0.1:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=570°C, the molar ratio of hydrogen / aromatics is 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0040] Comparative Example 2

[0041] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 3:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass loading of Cr2O3 is 15% and the mass content of hydrotalcite is 85%.

[0042] The alkyl aromatic hydrocarbon feedstock is the same as that in Example 1. 5 g of the aromatic hydrocarbon catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic hydrocarbon catalytic hydrogenation dealkylation reactor. The alkyl aromatic hydrocarbon feedstock is contacted with the aromatic hydrocarbon catalytic hydrogenation dealkylation catalyst under hydrogenation conditions to carry out a catalytic hydrogenation dealkylation reaction. The reaction conditions are: T = 570 ° C, the molar ratio of hydrogen to aromatic hydrocarbon is 5, and the C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0043] Comparative Example 3

[0044] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 3:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass content of Cr2O3 is 15% and the mass content of hydrotalcite is 85%.

[0045] The alkyl aromatic feedstock is the same as in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and a gaseous oxidant N2O is added to the reaction system, wherein the gaseous oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O to hydrogen is 0.05:1000, and a catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T = 570 ° C, a hydrogen / aromatic molar ratio of 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0046] Comparative Example 4

[0047] Take 100g of magnesium aluminum hydrotalcite with a Mg / Al atomic ratio of 3:1, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass content of Cr2O3 is 15% and the mass content of hydrotalcite is 85%.

[0048] The alkyl aromatic hydrocarbon feedstock is the same as that in Example 1. 5 g of the aromatic hydrocarbon catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic hydrocarbon catalytic hydrogenation dealkylation reactor. The alkyl aromatic hydrocarbon feedstock is contacted with the aromatic hydrocarbon catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and a polar compound methanol is added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic hydrocarbon feedstock and introduced into the reaction system. The mass ratio of methanol to the alkyl aromatic hydrocarbon feedstock is 0.1:1000, and a catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T = 570 ° C, a hydrogen / aromatic hydrocarbon molar ratio of 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0049] Comparative Example 5

[0050] Take 70g of ZSM-5 molecular sieve with a silicon-aluminum molar ratio of 30, add 30g of γ-Al2O3, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass loading of Cr2O3 is 15% and the mass content of ZSM-5 molecular sieve is 85%.

[0051] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and the polar compound methanol and the gas oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gas oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.05:1000, and the mass ratio of methanol and alkyl aromatic feedstock is 0.1:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=570°C, the molar ratio of hydrogen / aromatics is 5, C9 / C 10 Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 5.0MPa. The reaction results are shown in Table 1.

[0052] Comparative Example 6

[0053] Take 70g of ZSM-5 molecular sieve with a silicon-aluminum molar ratio of 30, add 30g of γ-Al2O3, then add 4g of dilute nitric acid, 2g of sesbania powder and 1g of cellulose, mix thoroughly, extrude into strips, and calcine at 550°C for 5h to prepare a carrier. Dissolve chromium nitrate in water, impregnate the surface of the above carrier, dry at 120°C for 4 hours, and calcine at 650°C for 3 hours to prepare an aromatic catalytic hydrogenation dealkylation catalyst, in which the mass loading of Cr2O3 is 15% and the mass content of ZSM-5 molecular sieve is 85%.

[0054] The alkyl aromatic feedstock is the same as that in Example 1. 5 g of the aromatic catalytic hydrogenation dealkylation catalyst in the example is loaded into an aromatic catalytic hydrogenation dealkylation reactor. The alkyl aromatic feedstock is contacted with the aromatic catalytic hydrogenation dealkylation catalyst under hydrogenation conditions, and the polar compound methanol and the gaseous oxidant N2O are added to the reaction system, wherein the polar compound is mixed with the alkyl aromatic feedstock and introduced into the reaction system, and the gaseous oxidant is mixed with hydrogen and introduced into the reaction system. The volume ratio of N2O and hydrogen is 0.05:1000, and the mass ratio of methanol and alkyl aromatic feedstock is 0.1:1000. The catalytic hydrogenation dealkylation reaction is carried out under the following reaction conditions: T=380°C, the molar ratio of hydrogen / aromatics is 3, C9 / C 10Monocyclic aromatic feed mass space velocity WHSV = 2h -1 , reaction pressure 3.0MPa. The reaction results are shown in Table 1.

[0055] Table 1 Aromatic catalytic hydrodealkylation performance of each embodiment and comparative example

[0056]

[0057]

[0058] The above detailed description of the specific implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features are combined in any other suitable manner, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention, all belong to the protection scope of the present invention.

Claims

1. A method for reducing C2 + The method for deep cracking of side chains comprises the steps of contacting an alkyl aromatic hydrocarbon feedstock with an aromatic hydrocarbon catalytic hydrodealkylation catalyst under hydrogenation conditions, characterized in that: A polar compound and a gaseous oxidant are added to the reaction system.

2. The method according to claim 1, characterized in that The polar compound is at least one of methanol, water and ethanol; and / or the mass ratio of the polar compound to the alkyl aromatic hydrocarbon feedstock is (0.05-0.5):1000; and / or the alkyl aromatic hydrocarbon in the alkyl aromatic hydrocarbon feedstock is C2 + Aromatic hydrocarbons with C9 or above as side chain substituents, preferably C2 + The C9 and C 10 Monocyclic aromatic hydrocarbons.

3. The method according to claim 1, characterized in that: The gas oxidant is a weak gas oxidant, preferably CO2 and / or N2O.

4. The method according to claim 3, characterized in that The volume ratio of the weak gas oxidant to hydrogen is (0.005-0.1):1000.

5. The method according to claim 1, characterized in that The aromatic hydrocarbon catalytic hydrodealkylation catalyst comprises a carrier hydrotalcite and an active component transition metal oxide.

6. The method according to claim 5, characterized in that The hydrotalcite is magnesium-aluminum hydrotalcite, and the atomic ratio of Mg / Al in the magnesium-aluminum hydrotalcite is 1-10, preferably 3-5.

7. The method according to claim 5, characterized in that The transition metal oxide is at least one of chromium oxide, nickel oxide, cobalt oxide, rhodium oxide, platinum oxide and palladium oxide.

8. The method according to claim 5, characterized in that Based on the mass of the catalyst, the mass content of the transition metal oxide is 1% to 30%, preferably 3% to 15%.

9. The method according to claim 1, characterized in that: The reaction conditions are: temperature of 500-800°C, weight space velocity of alkyl aromatic raw material of 0.5-5h -1 , the molar ratio of hydrogen to alkyl aromatics is 1 to 10, and the reaction pressure is 1 to 10 MPa.

10. The method according to claim 1, characterized in that The reaction conditions are: temperature of 550-700°C, weight space velocity of alkyl aromatic hydrocarbon raw material of 1-2h -1 , the molar ratio of hydrogen / alkyl aromatics is 5 to 7, and the reaction pressure is 4 to 6 MPa.

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