Method for selective hydrogenation of pyrolysis gasoline and application

Abstract

The present invention relates to the field of selective hydrogenation reactions, and discloses a pyrolysis gasoline selective hydrogenation method and applications thereof, the method comprises: feeding a raw material into a primary hydrogenation reactor, and carrying out a selective hydrogenation reaction through an upper bed layer and a lower bed layer; wherein the volume ratio of the upper bed catalyst to the lower bed catalyst is 1: (2-4); wherein the upper bed layer catalyst comprises a first alumina carrier, Pd and / or Pd oxide; the lower bed catalyst comprises a second alumina carrier, Pd and / or Pd oxide. According to the method, the raw materials and the catalyst with special structure and composition are subjected to hydrogenation reaction, the catalyst activity and selectivity are improved through matching of the volume ratio of the two hydrogenation catalysts, and the method can be used in industrial production of selective hydrogenation of pyrolysis gasoline and is beneficial to coupling utilization of device energy.

Description

Technical Field

[0001] The present invention relates to the field of selective hydrogenation reactions, and particularly to a method and application for the selective hydrogenation of pyrolysis gasoline. Background Art

[0002] The utilization of pyrolysis gasoline in ethylene plants is one of the main ways to improve the comprehensive economic benefits of the plants. Due to the complex composition and poor thermal stability of pyrolysis gasoline, generally, it is first selectively hydrogenated in one stage to remove diolefins and styrene, and then hydrodesulfurized in the second stage, and is mainly used for aromatics extraction. Currently, the catalysts mainly used for the selective hydrogenation of pyrolysis gasoline in industry are Pd-based or Ni-based catalysts, and the hydrogenation process for the middle distillate (C 6 -C 8 hydrocarbon compound fraction) or the full distillate (C 5 hydrocarbon - hydrocarbon compound fraction with a dry point of 204 °C).

[0003] With the increasing requirements for environmental protection and energy conservation in modern enterprises, on the one hand, various refining and chemical enterprises achieve new and higher requirements through integrated resource allocation schemes between enterprises and the external, between refining and chemical, and between units. On the other hand, they also actively carry out energy conservation analysis, energy optimization, adopt new technologies, and strengthen management within the units to continuously reduce the energy consumption of the units and reduce various emissions. In recent years, the energy consumption optimization of pyrolysis gasoline hydrogenation units has been carried out from aspects such as new trays and hot high-pressure separator transformation, and various beneficial attempts and improvements have also been made from aspects such as process flow and energy optimization.

[0004] In the traditional two-stage hydrogenation process, the second-stage heating furnace has been widely criticized due to its low energy efficiency, dispersed waste gas emissions and difficult treatment, and there have been calls to cancel it. However, due to the relatively low selectivity of conventional one-stage hydrogenation catalysts, most of the heat released during hydrogenation is released as low-temperature heat in the first stage, and the high-temperature hydrogenation heat release in the second stage cannot achieve self-thermal balance and must be compensated by the heating furnace. The shutdown of the second-stage heating furnace has become one of the most important indicators for energy conservation and consumption reduction, and whether to shut down the heating furnace depends on whether the selectivity of the one-stage selective hydrogenation catalyst is high enough.

[0005] Therefore, how to reduce the energy consumption of the unit in the pyrolysis petroleum hydrogenation reaction while taking into account the high reaction activity and high hydrogenation selectivity of the pyrolysis petroleum hydrogenation reaction is an urgent problem to be solved at present. Summary of the Invention

[0006] The object of the present invention is to overcome the problems existing in the prior art, namely, the low selectivity of conventional hydrogenation catalysts and the energy consumption waste in the cracking petroleum hydrogenation reaction device, and to provide a method and application for the selective hydrogenation of pyrolysis gasoline. By subjecting the raw material to a hydrogenation reaction with a catalyst having a special structure and composition and coordinating the volume ratio of the two-stage hydrogenation catalysts, the improvement of both the activity and selectivity of the catalyst is taken into account, which can be used in the industrial production of the selective hydrogenation of pyrolysis gasoline and is conducive to the coupled utilization of the energy of the device.

[0007] To achieve the above object, in a first aspect of the present invention, a method for the selective hydrogenation of pyrolysis gasoline is provided, wherein the method comprises: feeding the raw material into a first-stage hydrogenation reactor, and performing a selective hydrogenation reaction through an upper bed and a lower bed;

[0008] wherein, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:2 - 4;

[0009] wherein, the upper bed catalyst comprises a first alumina support, Pd and / or Pd oxide; the lower bed catalyst comprises a second alumina support, Pd and / or Pd oxide.

[0010] Preferably, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:3 - 4.

[0011] Preferably, based on the total mass of the upper bed catalyst, the mass percentage content of Pd and / or Pd oxide is 0.1 - 0.2 wt%, preferably 0.15 - 0.2 wt%; the mass percentage content of the first alumina support is 99.8 - 99.9 wt%, preferably 99.8 - 99.85 wt%.

[0012] Preferably, based on the total mass of the lower bed catalyst, the mass percentage content of the second alumina support is 99.5 - 99.9 wt%, preferably 99.65 - 99.8 wt%; the mass percentage content of Pd and / or Pd oxide is 0.1 - 0.5 wt%, preferably 0.2 - 0.35 wt%.

[0013] Preferably, the preparation method of the upper bed catalyst comprises:

[0014] (1) Preparing a precursor solution containing a polyacrylic acid compound, an amine ligand and a Pd source, and the precursor solution is alkaline;

[0015] (2) Impregnating the first alumina support in the precursor solution and calcining.

[0016] In a second aspect of the present invention, an application of the method according to the first aspect in the selective hydrogenation of alkynes and / or diolefins in petroleum hydrocarbons is provided.

[0017] Through the above technical solutions, the beneficial effects obtained are as follows:

[0018] The method for selective hydrogenation of pyrolysis gasoline provided by the present invention conducts a hydrogenation reaction on the raw material through different catalysts, including an upper bed catalyst and a lower bed catalyst. The upper bed catalyst is a high-activity catalyst, and the lower bed catalyst is a high-selectivity catalyst. By the cooperation of the two-stage catalysts, the improvement of both the activity and selectivity of the catalyst is taken into account, and it can be used in the industrial production of selective hydrogenation of pyrolysis gasoline, which is beneficial to the coupled utilization of the energy of the device. Specific embodiments

[0019] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0020] The first aspect of the present invention provides a method for hydrogenation of pyrolysis gasoline, wherein the method includes: feeding the raw material into a first-stage hydrogenation reactor, passing through an upper bed and a lower bed, and conducting a selective hydrogenation reaction;

[0021] Wherein, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:2 - 4;

[0022] Wherein, the upper bed catalyst includes a first alumina support, Pd and / or Pd oxide; the lower bed catalyst includes a second alumina support, Pd and / or Pd oxide.

[0023] The method for hydrogenation of pyrolysis gasoline provided by the present invention conducts a hydrogenation reaction on the raw material with two-stage specially composed catalysts. Through the cooperation of the volume ratios of the two-stage hydrogenation catalysts in the upper and lower beds, the improvement of both the activity and selectivity of the catalyst is taken into account, and it can be used in the industrial production of selective hydrogenation of pyrolysis gasoline, which is beneficial to the coupled utilization of the energy of the device.

[0024] According to the present invention, preferably, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:2 - 4, such as 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or the range between any two of them, and preferably 1:3 - 4. In the present invention, the upper bed catalyst and the lower bed catalyst that meet the above volume ratio limitation are compound-loaded for hydrogenation reaction, and at the same time, high catalytic activity and high selectivity are satisfied.

[0025] According to the present invention, preferably, based on the total mass of the upper bed catalyst, the mass percentage content of Pd and / or Pd oxide is 0.1-0.2 wt%, preferably 0.15-0.2 wt%; the mass percentage content of the first alumina carrier is 99.8-99.9 wt%, preferably 99.8-99.85 wt%.

[0026] According to the present invention, preferably, based on the total mass of the lower bed catalyst, the mass percentage content of the second alumina carrier is 99.5-99.9 wt%, preferably 99.65-99.8 wt%; the mass percentage content of Pd and / or Pd oxide is 0.1-0.5 wt%, preferably 0.2-0.35 wt%.

[0027] In the present invention, there is no particular limitation on the loading method of Pd and / or Pd oxide in the lower bed catalyst, and those skilled in the art can impregnate Pd and / or Pd oxide according to known methods, and obtain the lower bed catalyst after drying and calcination.

[0028] In the present invention, there is no particular limitation on the source of the first alumina carrier, which can be commercially purchased or prepared by existing methods.

[0029] According to the present invention, the first alumina carrier is selected from at least one of δ-alumina, θ-alumina, κ-alumina, and α-alumina.

[0030] According to the present invention, preferably, the specific surface area of the first alumina carrier is 100-200 m 2 / g, such as 100 m 2 / g, 110 m 2 / g, 120 m 2 / g, 130 m 2 / g, 140 m 2 / g, 150 m 2 / g, 160 m 2 / g, 170 m 2 / g, 180 m 2 / g, 190 m 2 / g, 200 m 2 / g, or the range between any two of them, preferably 100-180 m 2 / g.

[0031] According to the present invention, preferably, the pore volume of the first alumina carrier is 0.65-0.95 mL / g, such as 0.65 mL / g, 0.7 mL / g, 0.75 mL / g, 0.8 mL / g, 0.85 mL / g, 0.9 mL / g, or the range between any two of them, preferably 0.65-0.85 mL / g.

[0032] In the present invention, the upper bed catalyst prepared from the first alumina support having the above specific surface area and pore volume has high hydrogenation activity. In the present invention, the parameters of the specific surface area and pore volume are measured by the BET nitrogen adsorption method.

[0033] According to the present invention, preferably, the preparation method of the upper bed catalyst includes:

[0034] (1) Prepare a precursor solution containing a polyacrylic acid compound, an amine ligand, and a Pd source, and the precursor solution is alkaline;

[0035] (2) Immerse the first alumina support in the precursor solution and calcine it.

[0036] In the upper bed catalyst of the present invention, a polyacrylic acid compound is used as a dispersant in combination with an amine ligand during the preparation process. Through the anchoring effect of the polyacrylic acid compound, the dispersion of Pd particles is improved, and it has high catalytic activity and good stability at the same time, and the preparation method is simple.

[0037] According to the present invention, preferably, the mass ratio of the first alumina support to the polyacrylic acid compound in the precursor solution is 1:0.005 - 0.03, such as 1:0.005, 1:0.1, 1:0.015, 0:0.2, 1:0.025, 1:0.03, or the range between any two of them, preferably 1:0.01 - 0.02.

[0038] According to the present invention, preferably, the polyacrylic acid compound is selected from at least one of polyacrylic acid, sodium polyacrylate, and ammonium polyacrylate. According to the present invention, preferably, the polyacrylic acid compound is selected from at least one of polyacrylic acid, sodium polyacrylate, and ammonium polyacrylate. In the present invention, the polyacrylic acid compound plays an anchoring role. Through the molecular chain of the polyacrylic acid compound, the support is connected to the Pd particles, preventing the Pd particles from further entering the interior of the support, ensuring that the Pd particles are loaded on the surface of the support, and ensuring the high catalytic activity of the catalyst while reducing the Pd loading amount.

[0039] According to the present invention, preferably, the weight average molecular weight of the polyacrylic acid is 3000 - 5000 g / mol. In the present invention, if the molecular weight of the polyacrylic acid is too small and the molecular chain is too short, its steric hindrance cannot prevent the Pd particles from entering the interior of the support, resulting in Pd waste. If the molecular weight of the polyacrylic acid is too large and the molecular chain is too long, the loading amount will be reduced and the catalytic activity of the catalyst will decline.

[0040] In the present invention, the weight-average molecular weight of the ammonium polyacrylate is not particularly limited, and the weight-average molecular weight is not used as an index for controlling the ammonium polyacrylate. In the present invention, while the ammonium polyacrylate can play an anchoring role, it can also play a role in adjusting the pH value without introducing other elements. Preferably, the weight-average molecular weight of the ammonium polyacrylate is 5000-7000 g / mol.

[0041] According to the present invention, in the precursor solution, the addition amount of the amine ligand is not particularly limited. Preferably, the addition amount of the amine ligand is such that the pH value of the precursor solution is alkaline, and those skilled in the art can adaptively adjust the addition amount of the amine ligand according to the pH value of the precursor solution.

[0042] According to the present invention, preferably, the pH value of the precursor solution is 8-12, preferably 9-11. Adjusting the pH value of the precursor solution to meet the above range limitations, if the pH value is too high, it will affect the distribution of Pd on the surface of the carrier and reduce the catalytic activity.

[0043] According to the present invention, preferably, the amine ligand is ethylenediamine and / or ammonia water, preferably ethylenediamine. In the present invention, using the above amine ligand, on the one hand, it plays a coordination role, and on the other hand, it plays a role in adjusting the pH, and there is no need to additionally introduce a pH regulator. In the present invention, the amine ligand is preferably ethylenediamine, which has good coordination effect and will not produce precipitation when added to the precursor solution.

[0044] According to the present invention, preferably, in the precursor solution, the mass concentration of the Pd source is 0.03-0.1 wt%, preferably 0.04-0.08 wt%.

[0045] According to the present invention, preferably, the Pd source is selected from at least one of chloropalladic acid, palladium chloride, and palladium nitrate, preferably chloropalladic acid.

[0046] According to the present invention, the type of the Pd source is not particularly limited and can be a conventional water-soluble Pd compound in the art. Preferably, the Pd source is selected from at least one of chloropalladic acid, palladium chloride, and palladium nitrate, preferably chloropalladic acid.

[0047] In the present invention, the solvent of the precursor solution is water.

[0048] In the present invention, the preparation method of the precursor solution is not particularly limited, and the polyacrylic acid compound, the amine ligand, and the Pd source can be added together or separately. According to a preferred embodiment of the present invention, an aqueous solution containing the Pd source is prepared, the polyacrylic acid compound is added, and then the amine ligand is added to make the pH value of the precursor solution alkaline.

[0049] According to the present invention, preferably, the mass ratio of the carrier to the precursor solution is 1:2 - 6, such as 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, or the range between any two of them, preferably 1:3 - 5.

[0050] According to the present invention, there are no particular limitations on the impregnation conditions, and those skilled in the art can adaptively select conventional impregnation conditions to ensure that Pd is impregnated onto the carrier. Preferably, the impregnation conditions include: at room temperature, the impregnation time is 20 - 80 min, preferably 30 - 60 min.

[0051] In the present invention, preferably, the impregnation process further includes stirring and / or ultrasonic treatment, and there are no particular limitations on the stirring conditions and ultrasonic conditions, and those skilled in the art can select conventional stirring conditions and ultrasonic conditions.

[0052] According to the present invention, preferably, step (2) further includes a process of drying the impregnated product.

[0053] According to the present invention, there are no particular limitations on the drying method and drying conditions, and those skilled in the art can select conventional drying methods and drying conditions. According to a preferred embodiment of the present invention, after filtering the impregnated product, drying is carried out. Preferably, the drying conditions include: the drying temperature is 100 - 120 °C; the drying time is 1 - 4 h.

[0054] According to the present invention, preferably, the calcination conditions include: the calcination temperature is 400 - 550 °C, preferably 420 - 550 °C; the calcination time is 2 - 6 h, preferably 3 - 5 h. Preferably, the calcination is carried out in an air atmosphere.

[0055] According to the present invention, preferably, the method for preparing the second alumina carrier includes: mixing alumina hydrate A and alumina B, adding water and a peptizing agent, and performing shaping, drying, and calcination.

[0056] In the present invention, there are no particular limitations on the amounts of water and peptizing agent added, and those skilled in the art can adaptively adjust according to the shaping situation. The peptizing agent is a conventional peptizing agent in the art, preferably selected from at least one of nitric acid, acetic acid, and hydrochloric acid.

[0057] In the present invention, there are no particular limitations on the conditions of shaping, drying, and calcination, which are conventional shaping, drying, and calcination conditions in the art. Preferably, an extrusion molding method is adopted.

[0058] In the present invention, preferably, the calcination conditions include: the calcination temperature is 800 - 1200 °C, preferably 900 - 1200 °C; the calcination time is 1 - 10 h, preferably 2 - 8 h.

[0059] According to the present invention, preferably, the mass ratio of the alumina hydrate A to the alumina B is 1:(0.1 - 1), such as 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, or the range between any two of them, preferably 1:(0.2 - 0.5).

[0060] According to the present invention, preferably, the specific surface area of the second alumina support is 70 - 120 m 2 / g, and the pore volume is 0.4 - 0.8 mL / g.

[0061] According to the present invention, preferably, the alumina hydrate A is selected from at least one of alumina hydrates having a pseudoboehmite structure. Preferably, it is pseudoboehmite.

[0062] According to the present invention, preferably, the specific surface area of the alumina hydrate A is 300 - 450 m 2 / g, and the pore volume is 0.5 - 1.2 mL / g.

[0063] According to the present invention, preferably, the alumina B is selected from at least one of δ-alumina, θ-alumina, κ-alumina, and α-alumina.

[0064] According to the present invention, preferably, the specific surface area of the alumina B is 50 - 250 m 2 / g, and the pore volume is 0.3 - 0.8 mL / g.

[0065] According to the present invention, the hydrogenation conditions are as follows: the reaction pressure is 2 - 3 MPa, preferably 2.5 - 3 MPa; the reaction temperature is 30 - 60 °C, preferably 35 - 50 °C; the liquid hourly space velocity is 1.5 - 4 h -1 , preferably 2 - 3.5 h -1 ; the hydrogen-to-oil volume ratio is (60 - 100):1, preferably (50 - 70):1.

[0066] According to a preferred embodiment of the present invention, the hydrogenation reaction is carried out in a single-stage hydrogenation reactor, which includes at least two stages of composite catalyst beds.

[0067] In the present invention, before the upper bed catalyst and the lower bed catalyst are used for the hydrogenation reaction of pyrolysis gasoline, it further includes a step of reducing the catalyst, and the reduction conditions are the conventional catalyst reduction conditions in the art, without special limitation.

[0068] The second aspect of the present invention provides the application of the method described in the first aspect in the selective hydrogenation of alkynes and / or diolefins in petroleum hydrocarbons.

[0069] According to the present invention, preferably, it is used in the selective hydrogenation of pyrolysis gasoline.

[0070] In the present invention, the pyrolysis gasoline has its conventional meaning in the art and contains aromatic hydrocarbons, olefins and paraffins from C5 to C9. Preferably, the pyrolysis gasoline is an intermediate fraction of C6-C8 hydrocarbon compounds.

[0071] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, the reagents used in the present invention are all commercially available.

[0072] Preparation Example 1

[0073] Preparation of the upper bed catalyst C1-1

[0074] (1) Prepare an 80 g aqueous solution of chloropalladic acid with a palladium content of 0.05 wt%, add ethylenediamine to adjust the pH to 10.5, and then add 1 g of 40 wt% ammonium polyacrylate (Aladdin catalog number P304873) to obtain a precursor solution;

[0075] (2) Take 20 g of alumina support (the pore structure is shown in Table 1), slowly add the precursor solution to the support for impregnation, stir at room temperature for 45 min, filter the impregnated product, dry at 120 °C for 2 h, and calcine at 500 °C for 4 h to obtain a catalyst with a Pd content of 0.2 wt%.

[0076] Preparation of the lower bed catalyst C1-2

[0077] Weigh 200 g of pseudoboehmite A, 100 g of alumina B, and 9 g of talc powder, mix them, and then add 240 ml of an aqueous solution containing 6.0 g of nitric acid, and extrude them into Trilobite of [mm], the wet strips are dried at 50 °C for 24 hours and then calcined at 1050 °C for 6 hours to obtain the alumina support Z1-2. Then, impregnate with PdCl 2 Solution, dry at 110 °C for 2 hours and calcine at 450 °C for 4 hours to obtain a catalyst with a Pd content of 0.3 wt%. The catalyst composition and properties are shown in Table 1.

[0078] Preparation Example 2

[0079] Preparation of the upper bed catalyst C2-1

[0080] (1) Prepare an 80 g aqueous solution of chloropalladic acid with a palladium content of 0.08 wt%, add ethylenediamine to adjust the pH to 10.5, and add 1 g of 40 wt% ammonium polyacrylate (Aladdin catalog number P304873) to obtain a precursor solution;

[0081] (2) Take 20 g of alumina support (pore structure is shown in Table 1), slowly add the precursor solution to the support for impregnation, stir at room temperature for 45 min, filter the impregnated product, dry at 120 °C for 2 h, and calcine at 550 °C for 4 h to obtain a catalyst with a Pd content of 0.2 wt%.

[0082] Preparation of the lower bed catalyst C2-2

[0083] Weigh 250 g of pseudo-boehmite A, 50 g of alumina B, and 9 g of talc powder, mix them, and then add 225 mL of an aqueous solution containing 4.5 g of nitric acid, and extrude it into trilobes with a diameter of φ mm. After drying the wet strips at 50 °C for 24 h, calcine them at 1050 °C for 6 h to obtain the alumina support Z2-2. Then, impregnate with PdCl 2 solution according to the known method, dry at 110 °C for 2 h, and calcine at 450 °C for 4 h to obtain a catalyst with a Pd content of 0.3 wt%.

[0084] Preparation Example 3

[0085] Preparation of the upper bed catalyst C3-1

[0086] (1) Prepare an 80 g aqueous solution of chloropalladic acid with a Pd content of 0.05 wt%, adjust the pH to 10.5 by adding ethylenediamine, and then add 1 g of 40 wt% ammonium polyacrylate (Aladdin product number P304873) to obtain the precursor solution;

[0087] (2) Take 20 g of alumina support (pore structure is shown in Table 1), slowly add the precursor solution to the support for impregnation, stir at room temperature for 45 min, filter the impregnated product, dry at 120 °C for 2 h, and calcine at 500 °C for 4 h to obtain a catalyst with a Pd content of 0.18 wt%.

[0088] Preparation of the lower bed catalyst C3-2

[0089] Weigh 230 g of pseudo-boehmite A, 70 g of alumina B, and 9 g of talc powder, mix them, and then add 225 mL of an aqueous solution containing 5.4 g of nitric acid, and extrude it into trilobes with a diameter of φ2.5 mm. After drying the wet strips at 50 °C for 24 h, calcine them at 1050 °C for 6 h to obtain the alumina support Z3-2. Then, impregnate with PdCl 2 solution according to the known method, dry at 110 °C for 2 h, and calcine at 450 °C for 4 h to obtain a catalyst with a Pd content of 0.3 wt%.

[0090] Preparation Example 4

[0091] Preparation of the upper bed catalyst C4-1

[0092] (1) Prepare 80 g of an aqueous solution of chloropalladic acid with a palladium content of 0.05 wt%, add ethylenediamine to adjust the pH to 10.5, and then add 1 g of 40 wt% ammonium polyacrylate (Aladdin product number P304873) to obtain a precursor solution;

[0093] (2) Take 20 g of an alumina support (pore structure is shown in Table 1), slowly add the precursor solution to the support for impregnation, stir at room temperature for 45 min, filter the impregnated product, dry at 120 °C for 2 h, and calcine at 500 °C for 4 h to obtain a catalyst with a Pd content of 0.2 wt%.

[0094] Preparation of the lower bed catalyst C4-2

[0095] Weigh 150 g of pseudo-boehmite A, 150 g of alumina B, and 9 g of talc powder, mix them, and then add 240 ml of an aqueous solution containing 6.0 g of nitric acid, extrude them into clover-shaped pellets with a diameter of φ2.5 mm, dry the wet pellets at 50 °C for 24 h, and then calcine at 1050 °C for 6 h to obtain an alumina support Z4-2. Then, impregnate with Pd Cl 2 solution according to a known method, dry at 110 °C for 2 h, and calcine at 450 °C for 4 h to obtain a catalyst with a Pd content of 0.3 wt%.

[0096] Preparation Example 5

[0097] Preparation of the upper bed catalyst C5-1

[0098] (1) Prepare 80 g of an aqueous solution of chloropalladic acid with a palladium content of 0.05 wt%, add ethylenediamine to adjust the pH to 10.5, and then add 1 g of 40 wt% ammonium polyacrylate (Aladdin product number P304873) to obtain a precursor solution;

[0099] (2) Take 20 g of an alumina support (pore structure is shown in Table 1), slowly add the precursor solution to the support for impregnation, stir at room temperature for 45 min, filter the impregnated product, dry at 120 °C for 2 h, and calcine at 500 °C for 4 h to obtain a catalyst with a Pd content of 0.2 wt%.

[0100] Preparation of the lower bed catalyst C5-2

[0101] Weigh 200 g of pseudo-boehmite A, 100 g of alumina B, and 9 g of talc powder, mix them, and then add 225 ml of an aqueous solution containing 5.4 g of nitric acid, extrude them into clover-shaped pellets with a diameter of φ2.5 mm, dry the wet pellets at 50 °C for 24 h, and then calcine at 1050 °C for 6 h to obtain an alumina support Z5-2. Then, impregnate with PdCl 2 solution according to a known method, dry at 110 °C for 2 h, and calcine at 450 °C for 4 h to obtain a catalyst with a Pd content of 0.3 wt%.

[0102] The compositions and properties of the upper bed catalyst and the lower bed catalyst are shown in Table 1.

[0103] Table 1

[0104]

[0105] Examples 1-5

[0106] The catalysts prepared in Preparation Examples 1-5 were respectively taken and compound-filled into a hydrogenation reactor according to a volume ratio of the upper bed catalyst to the lower bed catalyst of 1:3 (a total of 100 mL).

[0107] Reduction was carried out for 8 hours under the conditions of a hydrogen pressure of 2.7 MPa, a temperature of 110 °C, and a hydrogen flow rate of 4 mL / (min·g catalyst). Under the conditions of a hydrogen pressure of 2.7 MPa, an inlet temperature of 40 °C, and a fresh oil space velocity of 3.0 h -1 (total space velocity of 12.0 h -1 ), the raw materials were fed for testing under the condition of a hydrogen / oil volume ratio of 70:1. The bromine value of the raw material was 34.29 g Br / 100 g oil, and the diolefin value was 18.02 g I / 100 g oil. The hydrogenation results after 120 hours are shown in Table 2.

[0108] Comparative Example 1

[0109] 100 mL of the catalyst C1-1 prepared in Preparation Example 1 was taken, and the hydrogenation reaction was carried out according to the conditions of Example 1. The hydrogenation results after 120 hours are shown in Table 2.

[0110] Comparative Example 2

[0111] 100 mL of the catalyst C1-2 prepared in Preparation Example 1 was taken, and the hydrogenation reaction was carried out according to the conditions of Example 1. The hydrogenation results after 120 hours are shown in Table 2.

[0112] Table 2

[0113]

[0114] It can be seen from Table 2 that, compared with the comparative examples, Examples 1-5 all have higher diolefin hydrogenation selectivity on the basis of ensuring the activity of the catalyst.

[0115] Example 6

[0116] 100 mL of the catalyst prepared in Preparation Example 1 was taken, the filling ratio of the upper bed catalyst to the lower bed catalyst was changed, and reduction was carried out for 8 hours under the conditions of a hydrogen pressure of 2.7 MPa, a temperature of 80 °C, and a hydrogen flow rate of 4 mL / (min·g catalyst). Under the conditions of a hydrogen pressure of 2.7 MPa, an inlet temperature of 40 °C, and a fresh oil space velocity of 3.0 h -1 (total space velocity of 12.0 h -1) Under the condition of a hydrogen / oil volume ratio of 70:1, the raw materials were introduced for testing. The bromine value of the raw materials was 34.3 g Br / 100 g oil, and the diolefin value was 19.5 g I / 100 g oil. The hydrogenation results are shown in Table 3.

[0117] Table 3

[0118]

[0119]

[0120] It can be seen from the results in Table 3 that by using the catalyst composite loading method of the present invention, relatively high diolefin hydrogenation selectivity can be obtained.

[0121] Example 7

[0122] Test results of changing the evaluation conditions of the catalyst prepared in Preparation Example 1 in the selective hydrogenation of cracked gasoline.

[0123] A total of 100 ml of the catalyst prepared in Preparation Example 1 was taken and loaded according to the volume ratio of the upper bed catalyst to the double bed catalyst of 1:3. The reduction process of Example 6 was repeated, the raw materials were introduced, and the test was carried out by changing a single process condition. The bromine value of the raw materials was 34.3 g Br / 100 g oil, and the diolefin value was 19.5 g I / 100 g oil. The hydrogenation results are shown in Table 4.

[0124] Table 4

[0125]

[0126] It can be seen from the results in Table 4 that by using the composite loading method and hydrogenation conditions of the catalyst loading method of the present invention, the diolefin hydrogenation selectivity of cracked gasoline is better.

[0127] 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 technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for selective hydrogenation of pyrolysis gasoline, characterized in that, the method comprises: feeding the raw material into a first-stage hydrogenation reactor, passing through the upper bed and the lower bed, and carrying out selective hydrogenation reaction; wherein, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:2 - 4; wherein, the upper bed catalyst comprises a first alumina support, Pd and / or Pd oxide; the lower bed catalyst comprises a second alumina support, Pd and / or Pd oxide.

2. The method according to claim 1, wherein, the volume ratio of the upper bed catalyst to the lower bed catalyst is 1:3 - 4; preferably, based on the total mass of the upper bed catalyst, the mass percentage content of Pd and / or Pd oxide is 0.1 - 0.2 wt%, preferably 0.15 - 0.2 wt%; the mass percentage content of the first alumina support is 99.8 - 99.9 wt%, preferably 99.8 - 99.85 wt%; preferably, based on the total mass of the lower bed catalyst, the mass percentage content of the second alumina support is 99.5 - 99.9 wt%, preferably 99.65 - 99.8 wt%; the mass percentage content of Pd and / or Pd oxide is 0.1 - 0.5 wt%, preferably 0.2 - 0.35 wt%.

3. The method according to claim 2, wherein, the first alumina support is selected from at least one of δ-alumina, θ-alumina, κ-alumina and α-alumina; Preferably, the specific surface area of the first alumina support is 100 - 200 m 2 / g, preferably 100 - 180 m 2 / g; preferably, the pore volume of the first alumina support is 0.65 - 0.95 mL / g, preferably 0.65 - 0.85 mL / g.

4. The method according to any one of claims 1 - 3, wherein, the preparation method of the upper bed catalyst comprises: (1) preparing a precursor solution containing a polyacrylic acid compound, an amine ligand and a Pd source, and the precursor solution is alkaline; (2) impregnating the first alumina support in the precursor solution and calcining.

5. The method according to claim 4, wherein, the mass ratio of the first alumina support to the polyacrylic acid compound in the precursor solution is 1:0.005 - 0.03, preferably 1:0.01 - 0.02; preferably, the polyacrylic acid compound is selected from at least one of polyacrylic acid, sodium polyacrylate and ammonium polyacrylate; preferably, in the precursor solution, the addition amount of the amine ligand is such that the pH value of the precursor solution is alkaline; preferably, the pH value of the precursor solution is 8 - 12, preferably 9 - 11; preferably, the amine ligand is ethylenediamine and / or ammonia water, preferably ethylenediamine; preferably, in the precursor solution, the mass concentration of the Pd source is 0.03 - 0.1 wt%, preferably 0.04 - 0.08 wt%; preferably, the Pd source is selected from at least one of chloropalladic acid, palladium chloride and palladium nitrate, preferably chloropalladic acid.

6. The method according to claim 4 or 5, wherein, the conditions of the impregnation include: at room temperature, the impregnation time is 20 - 80 min, preferably 30 - 60 min; Preferably, step (2) further includes a process of drying the impregnated product; Preferably, the drying conditions include: the drying temperature is 100 - 120 °C; the drying time is 1 - 4 h; Preferably, the calcination conditions include: the calcination temperature is 400 - 550 °C, preferably 420 - 550 °C; the calcination time is 2 - 6 h, preferably 3 - 5 h.

7. The method according to claim 2, wherein, The method for preparing the second alumina support includes: mixing alumina hydrate A and alumina B, a solvent, and a peptizing agent, followed by shaping, drying, and calcination; Preferably, the mass ratio of alumina hydrate A to alumina B is 1:(0.1 - 1), preferably 1:(0.2 - 0.5); Preferably, the specific surface area of the second alumina support is 70-120 m 2 / g, and the pore volume is 0.4-0.8 mL / g.

8. The method according to claim 7, wherein, Alumina hydrate A is selected from at least one of alumina hydrates having a pseudo - boehmite structure; Preferably, the specific surface area of the aluminum hydrate A is 300 - 450 m 2 / g, and the pore volume is 0.5 - 1.2 mL / g; Preferably, alumina B is selected from at least one of δ - alumina, θ - alumina, κ - alumina, and α - alumina; Preferably, the specific surface area of the alumina B is 50-250 m 2 / g, and the pore volume is 0.3-0.8 mL / g.

9. The method according to any one of claims 1 - 8, wherein the hydrogenation conditions are: The reaction pressure is 2 - 3 MPa, preferably 2.5 - 3 MPa; the reaction temperature is 30 - 60 °C, preferably 35 - 50 °C; the liquid hourly space velocity is 1.5 - 4 h -1 , preferably 2 - 3.5 h -1 ; the hydrogen-to-oil volume ratio is (60 - 100):1, preferably (50 - 70):

1.

10. Use of the method according to any one of claims 1 - 9 in the selective hydrogenation of alkynes and / or diolefins in petroleum hydrocarbons; Preferably, use in the selective hydrogenation of pyrolysis gasoline.

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