CN109718794B

CN109718794B - Fluidized bed hydrogenation catalyst and preparation method thereof

Info

Publication number: CN109718794B
Application number: CN201711019735.9A
Authority: CN
Inventors: 隋宝宽; 吕振辉; 薛冬; 彭冲; 季洪海; 彭绍忠; 佟佳
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2017-10-27
Filing date: 2017-10-27
Publication date: 2021-11-09
Anticipated expiration: 2037-10-27
Also published as: CN109718794A

Abstract

The invention discloses a fluidized bed hydrogenation catalyst and a preparation method thereof. The preparation method of the boiling bed hydrogenation catalyst adopts a reaction system comprising N micro-reactors connected in series, wherein the first micro-reactor adopts an impinging stream reactor, nano aluminum hydroxide seed crystals, acidic materials and alkaline materials enter the first micro-reactor to perform parallel flow reaction, obtained products sequentially enter the second micro-reactor to the N-1 micro-reactor and repeatedly swing through the pH value, and obtained reaction product mixed liquid enters the N micro-reactor to perform aging reaction and roasting to obtain the boiling bed hydrogenation catalyst. Wherein the acidic materials are acidic aluminum salt solution and acidic active metal solution, and the alkaline materials are alkaline aluminate solution and alkaline active metal solution. The fluidized bed hydrogenation catalyst prepared by the method has larger aperture and pore volume, uniform grain size, higher density of the surface-phase active metal of the catalyst, elimination of amplification effect and suitability for the hydrodesulfurization and denitrification processes of heavy oil and residual oil.

Description

Fluidized bed hydrogenation catalyst and preparation method thereof

Technical Field

The invention relates to a fluidized bed hydrogenation catalyst and a preparation method thereof, in particular to a heavy oil and residual oil hydrodemetallization catalyst for a fluidized bed and a preparation method thereof.

Background

In recent years, microreactors have attracted tremendous academic and commercial interest to researchers in many fields. This interest has been generated by the following features of microtechnology including size reduction, productivity enhancement, scaling up of the system to any desired production capacity (i.e., "capacity expansion"), increased heat transfer and increased mass transfer. Certain work related to microreactors has been reviewed by Gavilididis et al in "Technology And Applications Of microbiological Reactors" Trans. IhemE, Vol.80, part A, pages 3-30 (2002, 1 month). The micro-reactor is a chemical reaction system with a unit reaction interface width of micron order, and is a micro-chemical technology which is started in the 90 s. Since the prediction and advantages of microreactors in the preparation of nanoparticles were reported in 2002 by deMello and co-workers, microchannel technology of microreactors and the like has become more and more popular in the preparation of nanocrystals. The microreactor has the following advantages: (1) the flow in the channel is laminar flow; (2) the specific surface area is large, the heat transfer capacity is strong, and the temperature control is easy; (3) short molecular diffusion distance and fast mass transfer.

The traditional supported hydrogenation catalyst is limited by a carrier pore structure, the loading amount of active metal is generally not more than 30wt%, the number of active centers provided by the supported catalyst is limited, although the number and the type distribution of the active centers can be optimized and adjusted, the limit bottleneck of the number of the active centers cannot be broken through, and the space for greatly improving the hydrogenation activity is limited. The bulk phase method for preparing the hydrogenation catalyst is mainly composed of active metal components, so that the limitation of metal content can be eliminated, the proportion of each active component in the catalyst can be adjusted at will, and the hydrogenation performance of the catalyst is improved. The technology of preparing bulk phase catalyst by coprecipitation method, adopting different precipitation modes and gelling conditions, etc. can greatly affect the pore structure of the catalyst, the active metal content and the active center density on the pore surface, the distribution of different hydrogenation active metals and the interaction relationship among different hydrogenation active metals. However, the catalyst prepared by the coprecipitation method has smaller aperture and pore volume, and is not suitable for preparing the heavy residual oil hydrodemetallization catalyst.

CN1951558A discloses a preparation method of a catalyst composition. Ni generation by coprecipitation_xW_yO_zComposite oxide precursor, then with MoO₃Pulping, mixing, filtering, shaping and activating to obtain the final catalyst. Wherein the coprecipitation method produces Ni_xW_yO_zThe method for preparing the composite oxide precursor comprises the following steps: preparing salt mixed solution containing active metal Ni and W components according to the content ratio of catalyst components, then adding the salt mixed solution and alkaline precipitant into a reaction tank filled with purified water in a concurrent flow manner to form gelThe pH value of the slurry in the reaction tank is 7.0-9.0, and the prepared gelatinous mixture is the composite oxide Ni_xW_yO_zThe precursor of (1). The catalyst prepared by the method has small aperture and pore volume, and is not suitable for preparing heavy oil and residual oil hydrodemetallization catalysts.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a fluidized bed hydrogenation catalyst and a preparation method thereof. The hydrogenation catalyst has the advantages of large pore diameter and pore volume, concentrated pore diameter distribution, uniform grain size distribution, higher density of the catalyst surface-phase active metal and higher utilization rate of the hydrogenation active metal. The method for preparing the hydrogenation catalyst has the advantages of simple process, short reaction time, high process continuity efficiency, elimination of amplification effect and suitability for industrial production.

The invention provides a fluidized bed hydrogenation catalyst, which is a bulk phase catalyst and comprises alumina and active metal components, wherein the grain size distribution of the hydrogenation catalyst is as follows: the crystal grains with the grain size of <100 mu m account for 1 to 5 percent of the total number of the crystal grains of the hydrogenation catalyst, the crystal grains with the grain size of 100 to 150 mu m account for 85 to 90 percent of the total number of the crystal grains of the hydrogenation catalyst, and the crystal grains with the grain size of >150 mu m account for 5 to 10 percent of the total number of the crystal grains of the hydrogenation catalyst.

The properties of the fluidized bed hydrogenation catalyst provided by the invention are as follows: the specific surface area is 200-250 m²The pore volume is 1.3-1.5 mL/g, and the pore size distribution is as follows: diameter of hole<The pore volume occupied by the pores with the diameter of 25nm is 5-10 percent of the total pore volume, the pore volume occupied by the pores with the diameter of 25-50 nm is 85-95 percent of the total pore volume, and the pore volume occupied by the pores with the diameter larger than 50nm is 5-10 percent of the total pore volume.

In the fluidized bed hydrogenation catalyst of the present invention, the content of the group VIII metal is 5wt% to 15wt%, preferably 5.0wt% to 10.0wt%, the content of the group VIB metal is 30wt% to 50wt%, preferably 30wt% to 45wt%, and the content of the alumina is 35wt% to 65wt%, preferably 45wt% to 65wt%, calculated as oxide.

According to the fluidized bed hydrogenation catalyst, active metal components are calculated by oxides, the weight content ratio of active metals of a surface phase VIII group to active metals of a bulk phase VIII group is 5.0: 1-11.0: 1, preferably 8.0-11.0: 1, and the weight content ratio of active metals of a surface phase VIB to active metals of a bulk phase VIB is 10.0: 1-25.0: 1, preferably 14.0: 1-21.0: 1.

In the boiling bed hydrogenation catalyst, the VIII group active metal is selected from one or more of Ni and Co, and the VIB group active metal is selected from one or more of Mo and W.

In the fluidized bed hydrotreating catalyst, the weight content of the surface phase VIII group active metal is the weight content of the VIII group active metal in the surface phase, and the weight content of the bulk phase VIII group active metal component is the weight content of the VIII group active metal in the catalyst; the weight content of the surface phase VIB active metal component is the weight content of VIB active metals in the surface phase, and the weight content of bulk VIB active metals is the weight content of VIB active metals in the catalyst. The content of the active metal of the catalyst surface phase is determined by X-ray photoelectron spectroscopy (XPS), and the content of the active metal of the catalyst bulk phase is determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

The invention provides a preparation method of a fluidized bed hydrogenation catalyst, wherein an adopted reaction system comprises N microreactors which are connected in series, a first microreactor, a second microreactor, … … and an Nth microreactor are respectively arranged along a material flow direction, the first microreactor adopts an impinging stream reactor, and the preparation method comprises the following steps:

(1) respectively preparing an alkaline material and an acidic material;

(2) respectively introducing an alkaline material and an acidic material into a first microreactor to perform a neutralization precipitation reaction; simultaneously adding nano aluminum hydroxide seed crystals into the first microreactor;

(3) the reaction product mixed liquid obtained in the step (2) sequentially enters a second micro-reactor to an N-1 micro-reactor, and the reaction system is repeatedly subjected to pH value swing;

(4) allowing the reaction product mixed solution obtained in the step (3) to enter an Nth micro reactor for aging reaction, allowing the effluent of the Nth micro reactor to enter a product collecting tank, and filtering, washing, drying and roasting to obtain a fluidized bed hydrogenation catalyst;

in the step (1), the alkaline materials are alkaline aluminate solution and alkaline active metal solution, the acidic materials are acidic aluminate solution and acidic active metal solution, the alkaline active metal solution is alkaline aqueous solution containing VIII group and VIB group active metals, and the acidic active metal solution is acidic aqueous solution containing VIII group and VIB group active metals.

In the method, N microreactors are connected in series, wherein N is an integer not less than 5, preferably 5-11, and more preferably 5-7.

In the method, when N microreactors are connected in series, the specific process of pH value swing in the step (3) is as follows:

the mixed solution of the reaction products obtained in the step (2) enters a second micro reactor, and simultaneously, an acid material is introduced into the second micro reactor, so that the reaction system swings to the acid side; and the reaction product mixed solution obtained by the second microreactor enters a third microreactor, and meanwhile, an alkaline material is introduced into the third microreactor, so that the reaction system swings … towards the alkaline side, the obtained reaction product mixed solution sequentially enters a fourth microreactor to an N-1 microreactor, and the reaction system repeatedly swings towards the acid side and towards the alkaline side.

In the preparation method of the boiling bed hydrogenation catalyst, an alkaline material and an acidic material are respectively prepared in the step (1), wherein the alkaline material is a mixed solution of an alkaline aluminate solution and an alkaline active metal solution, and the alkaline aluminate solution is selected from NaAlO₂Or KAlO₂One or two of the aqueous solutions, preferably NaAlO₂Aqueous solution, alkaline aluminum salt aqueous solution with concentration of Al₂O₃The amount is 20-200 g/100 mL; the concentration of the alkaline active metal aqueous solution is calculated by active metal oxides, the content of VIII group active metal oxides is 10-30 g/100mL, and the content of VIB group active metal oxides is 40-120 g/100 mL; wherein the acidic material is a mixed solution of an acidic aluminate solution and an acidic active metal solution, and the acidic aluminate solution is selected from AlCl₃、Al₂(SO₄)₃Or Al (NO)₃Preferably Al, in an aqueous solution of (a)₂(SO₄)₃、AlCl₃Aqueous solution, acidic aluminium salt aqueous solution with concentration of Al₂O₃The amount is 20-200 g/100 mL; the acidic active metal solution is an aqueous solution containing active metals of VIII and VIB groups, the concentration of the acidic active metal aqueous solution is calculated by active metal oxides, the content of the VIII group active metal oxides is 10-30 g/100mL, and the content of the VIB group active metal oxides is 40-120 g/100 mL.

In the preparation method of the boiling bed hydrogenation catalyst, the nano aluminum hydroxide seed crystal introduced in the step (2) can be introduced after being mixed with the acidic material and/or the alkaline material, and can also be independently introduced into the first microreactor. The grain size distribution of the nano aluminum hydroxide seed crystal is as follows:<5nm crystal grains account for 5-15% of the total number of the aluminum hydroxide crystal grains, 5-15 nm crystal grains account for 80-85% of the total number of the aluminum hydroxide crystal grains,>the number of 15nm crystal grains accounts for 10-15% of the total number of the aluminum hydroxide crystal grains, and the adding amount of the nano aluminum hydroxide crystal seeds is Al₂O₃Counting the amount of Al which is added as the alkaline material and the acidic material in the first micro-reactor₂O₃1 to 5 percent of the total amount.

In the preparation method of the pseudo-boehmite, the adding mode of the nano aluminum hydroxide seed crystal is preferably mixed with the alkaline material and/or the acidic material and then added, wherein when the alkaline material and the acidic material are simultaneously added into the nano aluminum hydroxide seed crystal, the concentrations of the nano aluminum hydroxide seed crystal in the alkaline material and the nano aluminum hydroxide seed crystal in the acidic material can be the same or different.

In the preparation method of the hydrogenation catalyst, in the step (2), the alkaline material and the acidic material are introduced into the first microreactor and are introduced in an atomization or liquid mode.

In the preparation method of the fluidized bed hydrogenation catalyst, the first microreactor adopts an impinging stream microreactor, two feed inlets of the impinging stream microreactor are respectively connected with an alkaline material and an acidic material, the alkaline material and the acidic material enter the impinging stream microreactor and then are communicated through a jet orifice, the jet orifice of the alkaline material and the jet orifice of the acidic material impact at a certain angle, and the impact angle is 150-180 degrees.

In the preparation method of the fluidized bed hydrogenation catalyst, the raw material tank, the first microreactor and the rest microreactors are heated by microwave radiation.

In the preparation method of the boiling bed hydrogenation catalyst, the precipitation reaction in the step (2) has the following reaction conditions: the reaction temperature is 50-150 ℃, preferably 50-120 ℃, and the pH value is 8.0-9.0. The diameter of an inner tube of the first micro-reactor is 10-20 mm, preferably 10-15 mm, and the residence time of materials is controlled to be 1-5 min, preferably 1-2 min.

In the step (2), the flow rate of the alkaline material is 10-50 mL/min, preferably 15-30 mL/min. The flow rate of the acidic material can be regulated and controlled according to the pH value required by the system.

In the preparation method of the boiling bed hydrogenation catalyst, when the reaction system swings to the alkali side in the step (3), the reaction conditions are controlled as follows: the reaction temperature is 20-30 ℃ lower than that of the first microreactor, and the pH value is 10.0-11.0. The diameter of an inner pipe of the micro reactor is 5-10 mm larger than that of the adjacent micro reactor, and the preferable diameter is 8-10 mm. The residence time of the materials in the micro-reactor is controlled to be 8-15 min, preferably 10-15 min.

In the preparation method of the boiling bed hydrogenation catalyst, when the reaction system swings to the acid side in the step (3), the reaction conditions are controlled as follows: the reaction temperature is 20-30 ℃ higher than that of the first microreactor, and the pH value is 3.0-5.0. The diameter of the inner pipe of the micro reactor is 1-10 mm larger than that of the adjacent micro reactor, and preferably 2-3 mm. The residence time of the materials in the micro-reactor is controlled to be 2-5 min, preferably 3-5 min

In the preparation method of the fluidized bed hydrogenation catalyst, the Nth microreactor in the step (4) carries out an aging process, and the aging conditions are controlled as follows: the aging temperature is 20-30 ℃ lower than that of the first microreactor, and the pH value is 8.0-9.0. Wherein, the pH value can be regulated and controlled by adopting the alkaline material or the acidic material prepared in the step (1) and also can be regulated and controlled by adopting other acidic or alkaline materials. The pipe diameter of the Nth micro-reactor is 5-10 mm larger than that of the Nth micro-reactor and is preferably 8-10 mm. The residence time in the Nth micro-reactor is 8-15 min, preferably 10-15 min.

In the preparation method of the boiling bed hydrogenation catalyst, in the step (4), the drying conditions are as follows: drying for 3-10 hours at 60-150 ℃; the roasting conditions are as follows: roasting at 450-650 deg.C for 2-15 hours.

Compared with the prior art, the hydrogenation catalyst and the preparation method thereof provided by the invention have the following advantages:

1. the boiling bed hydrogenation catalyst of the invention has larger aperture and pore volume, very centralized aperture distribution and uniform grain size distribution, and is particularly suitable for being used as a material for processing macromolecular raw materials or reactants, such as residual oil hydrodesulfurization and denitrification catalysts.

2. The invention relates to a method for preparing a boiling bed hydrogenation catalyst, which utilizes a micro reactor to lead the concentration of reactants to tend to be constant in the reaction process and combines with the pH value swing, namely, a first micro reactor adopts an impinging stream reactor, firstly, catalyst crystal nuclei are deposited on the surface of the first micro reactor under the action of nano crystal seeds, thus leading the generated catalyst crystal nuclei to be larger, higher in crystallinity and more concentrated in particle size distribution, then, the conditions of pH value swing are controlled, so that a high-temperature and rapid reaction mode is adopted when the subsequent acid side swings, on one hand, amorphous aluminum hydroxide in the hydrogenation catalyst is dissolved, more active metal is exposed to a surface phase, on the other hand, the high temperature promotes the nucleation speed, and stable and uniform crystal nuclei are formed, thus being beneficial to the formation of monodisperse crystals, and the alkali side swing adopts a low-temperature and slow-speed reaction mode, thus inhibiting the generation of new crystal nuclei in the growth stage, but directly grows on the formed crystal nucleus and fully reacts, so that the free energy of the system is reduced to the maximum extent, and the formed crystal grains can stably exist in a monodisperse state. The method of the invention is favorable for the concentrated pore size distribution of the hydrogenation catalyst, the uniform and concentrated distribution of crystal grains and good stability through the repeated acid side swing and alkali side swing. In addition, the method is beneficial to uniform and orderly accumulation of the crystal grains of the hydrogenation catalyst, centralized pore distribution and higher specific surface area and pore volume, can greatly improve the content of active metal in the hydrogenation catalyst, ensures that the surface phase of the catalyst has higher active metal density and higher utilization rate of the hydrogenation active metal.

3. According to the method for preparing the fluidized bed hydrogenation catalyst, the second micro reactor and the subsequent micro reactors are heated by microwave radiation, so that the problems that ions of microfluid close to a tube wall are preferentially nucleated after the moment of mass transfer and heating, even the ions are adhered to the tube wall due to heterogeneous nucleation caused by the action of the tube wall, the mass transfer rate is reduced, and the crystallization degree, the particle size distribution, the dispersity and the yield of crystal grains are further influenced due to agglomeration caused by high surface free energy of the crystal nucleus are solved.

4. Compared with the kettle type bulk phase synthesis method, the method for preparing the fluidized bed hydrogenation catalyst realizes the continuity of the reaction process, solves the problem of low production efficiency, has no amplification effect, and is very suitable for industrial production.

Drawings

FIG. 1 is a schematic flow diagram of the present invention employing 5 microreactors to prepare an ebullated-bed hydrogenation catalyst;

the device comprises a first micro reactor 1, a second micro reactor 2, a third micro reactor 3, a fourth micro reactor 4 and a fifth micro reactor 5.

Detailed Description

The hydrogenation catalyst and the process for preparing the same according to the present invention are described in more detail below by way of specific examples. The examples are merely illustrative of specific embodiments of the process of the present invention and do not limit the scope of the invention. In the present invention, wt% is a mass fraction.

In the examples of the present invention and comparative examples, NaAlO₂Solution and Al₂(SO₄)₃The concentration of the solution is Al₂O₃And (6) counting.

In the present invention, the particle size distribution of the hydrogenation catalyst is measured by a particle size distribution meter. The specific surface area, pore volume and pore size distribution of the hydrogenation catalyst are measured by a low-temperature liquid nitrogen adsorption-desorption method. The content of the active metal of the catalyst surface phase is determined by X-ray photoelectron spectroscopy (XPS), and the content of the active metal of the catalyst bulk phase is determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

The method of the present invention will be described in detail below with reference to FIG. 1, using 5 microreactors as an example. The preparation method of the fluidized bed hydrogenation catalyst comprises the following steps: respectively introducing an alkaline material and an acidic material containing nano aluminum hydroxide seed crystals into a first microreactor 1 to perform a neutralization precipitation reaction, wherein the first microreactor 1 adopts an impinging stream microreactor; the product mixed liquid obtained by the first micro reactor 1 enters the second micro reactor 2, and simultaneously, the acid material is introduced into the second micro reactor 2, so that the reaction system swings to the acid side; the reaction product mixed solution obtained by the second microreactor 2 enters a third microreactor 3, and meanwhile, an alkaline material is introduced into the third microreactor 3, so that the reaction system swings to the alkaline side; the mixed solution of the reaction products obtained by the third micro-reactor 3 enters the fourth micro-reactor 4, so that the reaction system swings to the acid side; the mixed solution of the reaction products obtained by the fourth micro-reactor 4 enters a fifth micro-reactor 5 for aging reaction, alkaline materials are added to adjust the pH value, the aged products enter a product collecting tank, and the boiling bed hydrogenation catalyst is obtained after filtration, washing, drying and roasting; the alkaline material is an alkaline aluminate solution and an alkaline active metal solution, the acidic material is an acidic aluminate solution and an acidic active metal solution, the alkaline active metal solution is an alkaline aqueous solution containing active metals of VIII group and VIB group, and the acidic active metal solution is an acidic aqueous solution containing active metals of VIII group and VIB group.

The grain size distribution of the added nano aluminum hydroxide seed crystal is as follows: the crystal grains with the diameter of <5nm account for 5.7 percent of the total number of the aluminum hydroxide crystal grains, the crystal grains with the diameter of 5-15 nm account for 81.2 percent of the total number of the aluminum hydroxide crystal grains, the crystal grains with the diameter of >15nm account for 13.1 percent of the total number of the aluminum hydroxide crystal grains,

in the examples of the present invention and the comparative examples, the inner tube diameters of the respective microreactors were as follows: the diameter of the inner tube of the first microreactor is 13mm, the diameter of the inner tube of the second microreactor is 16 mm, the diameter of the inner tube of the third microreactor is 25mm, the diameter of the inner tube of the fourth microreactor is 27mm, and the diameter of the inner tube of the fifth microreactor is 35 mm.

Example 1

This example describes the preparation of Mo and Ni raw solution. In this example, only one of Mo and Ni acidic active metal solution A1 and alkaline active metal solution B1 was prepared, and solutions of other ratios and concentrations were prepared according to the method described.

Preparation of acidic active metal solution a 1: putting 386g of molybdenum oxide and 123g of basic nickel carbonate into a multi-neck flask, adding a certain amount of deionized water, stirring until substances in the flask are in a slurry state, slowly adding 86g of phosphoric acid, slowly heating after an initial reaction, keeping the temperature of the solution at 90-110 ℃ for 1-3 hours, filtering the obtained solution while the solution is hot after stopping heating, and then adding phosphoric acid to adjust the pH value of the solution to 1.0-4.0 to obtain a clear dark green original solution. The composition of the solution is MoO₃：69.27g/100mL；NiO：12.49g/100mL。

Preparation of alkaline active metal solution B1: putting 296g of ammonium molybdate and 105g of nickel nitrate into a multi-mouth flask, adding a certain amount of deionized water, stirring until substances in the flask are in a slurry state, slowly adding 150g of ammonia water, slowly heating after the initial reaction, keeping the temperature of the solution at 70-80 ℃ for 1-2 hours, stopping heating, filtering the obtained solution while the solution is hot, and then adding ammonia water to adjust the pH value of the solution to 10.0-12.0 to obtain the required solution. The composition of the solution is MoO₃：58.2g/100mL；NiO：10.5g/100mL。

Example 2

NaAlO with the concentration of 100g/100mL₂Solution and alkaline active Metal solution B1 alkaline material and 85g/100mL Al concentration₂(SO₄)₃The solution and the acidic material of the acidic active metal solution A1 are added into respective component tanks, and nano aluminum hydroxide seed crystal is added into the component tank connected with the first microreactor, wherein NaAlO₂Adding the concentration of the nano aluminum hydroxide crystal seeds into the solution component tank to obtain Al₂O₃Calculated as 1g/100mL, Al₂(SO₄)₃The concentration of the nano aluminum hydroxide crystal seeds added into the solution component tank is Al₂O₃It was calculated as 4.25g/100 mL.

Heating the raw material tanks and the first impinging stream microreactor by microwaves, heating the raw material tanks and the first impinging stream microreactor to 120 ℃, starting booster pumps of the two component tanks, injecting an alkaline material and an acidic material into the first impinging stream reactor through the booster pumps, controlling the flow rate of the alkaline material to be 25mL/min, adjusting the pH value in the impinging stream reactor to be 8.3, carrying out a neutralization and precipitation reaction, and allowing a reaction mixed solution to stay in the first impinging stream microreactor for 1.2min and then enter a second microreactor; heating the reaction temperature of the second microreactor to 140 ℃ by adopting microwave heating, starting a booster pump of the second microreactor, injecting an acidic material into the second microreactor, controlling the pH value to be 3.1, and allowing a reaction mixed solution to stay in the second microreactor for 3.5min and then to enter a third microreactor; heating by microwave to raise the reaction temperature of the third microreactor to 90 ℃, starting a booster pump of the third microreactor, injecting an alkaline material into the third microreactor, controlling the pH value to be 10.2, and allowing a reaction mixed solution to stay in the third microreactor for 12min and then enter a fourth microreactor; heating by microwave to raise the reaction temperature of the fourth microreactor by 150 ℃, starting a booster pump of the fourth microreactor, injecting an acidic material into the fourth microreactor, controlling the pH value to be 4.1, and allowing a reaction mixed solution to stay in the fourth microreactor for 3min and then enter a fifth microreactor; heating the reaction temperature of the fifth microreactor to 95 ℃ by adopting microwave heating, starting a booster pump of the fifth microreactor, injecting an alkaline material into the fifth microreactor, controlling the pH value to be 8.3 for aging reaction, aging the reaction mixed liquid in the fifth microreactor for 15min, then feeding the reaction mixed liquid into a product collecting tank, filtering the product, drying the product at 120 ℃ for 3h, and roasting the product at 600 ℃ for 3h to obtain the hydrogenation catalyst A, wherein the particle size distribution and the pore structure of the hydrogenation catalyst A are shown in Table 1.

Example 3

NaAlO with the concentration of 85g/100mL₂Solution and alkaline active metal solution B2 (MoO)₃: 69.5g/100 mL; NiO: 15.2g/100 mL) of alkaline material and Al with a concentration of 100g/100mL₂(SO₄)₃Solution and acidic active Metal solution A2 (MoO)₃: 70.1g/100 mL; NiO: 15.3g/100 mL) of an acidic material was added to the respective component tank and the component tank connected to the first microreactor was charged with the acidic materialNano aluminum hydroxide seed crystal in which NaAlO₂Adding the concentration of the nano aluminum hydroxide crystal seeds into the solution component tank to obtain Al₂O₃Calculated as 1.7g/100mL, Al₂(SO₄)₃The concentration of the nano aluminum hydroxide crystal seeds added into the solution component tank is Al₂O₃The weight is 1g/100 mL.

Heating the raw material tanks, the first impinging stream microreactor and other microreactors by microwaves, heating the raw material tanks and the first impinging stream microreactor to 100 ℃, starting booster pumps of the two component tanks, injecting an acidic material and an alkaline material into the first impinging stream reactor through the booster pumps, controlling the flow rate of the alkaline material to be 15mL/min, adjusting the pH value of 9.0 in the impinging stream reactor, performing neutralization and precipitation reaction, and allowing a reaction mixed solution to stay in the first impinging stream microreactor for 2.0min and then enter a second microreactor; heating the reaction temperature of the second microreactor to 130 ℃ by adopting microwave heating, starting a booster pump of the second microreactor, injecting an acidic material into the second microreactor, controlling the pH value to be 3.8, and allowing a reaction mixed solution to stay in the second microreactor for 5min and then enter a third microreactor; heating by microwave to enable the reaction temperature of the third microreactor to be 70 ℃, starting a booster pump of the third microreactor, injecting an alkaline material into the third microreactor, controlling the pH value to be 10.2, and enabling a reaction mixed solution to stay in the third microreactor for 13min and then enter a fourth microreactor; heating by microwave to raise the reaction temperature of the fourth microreactor to 130 ℃, starting a booster pump of the fourth microreactor, injecting an acidic material into the fourth microreactor, controlling the pH value to be 3.9, and allowing a reaction mixed solution to stay in the fourth microreactor for 5min and then enter a fifth microreactor; heating the fifth microreactor to 80 ℃ by adopting microwave heating, starting a booster pump of the fifth microreactor, injecting an alkaline material into the fifth microreactor, controlling the pH value to be 8.5 for aging reaction, aging the reaction mixed liquid in the fifth microreactor for 12min, then feeding the reaction mixed liquid into a product collecting tank, filtering the product, drying the product at 120 ℃ for 3h, roasting the product at 600 ℃ for 3h to obtain a hydrogenation catalyst B, and measuring the particle size distribution and the pore structure of the hydrogenation catalyst B, wherein the particle size distribution and the pore structure are shown in Table 1.

Example 4

NaAlO with the concentration of 150g/100mL₂Solution and alkaline active metal solution B3 (MoO)₃: 51.2g/100 mL; NiO: 12.5g/100 mL) of alkaline material and Al with a concentration of 100g/100mL₂(SO₄)₃Solution and acidic active Metal solution A3 (MoO)₃: 49.5g/100 mL; NiO: 12.6g/100 mL) of an acidic material was added to the respective component tank and nano-aluminum hydroxide seed crystals, wherein NaAlO, were added to the component tank connected to the first microreactor₂Adding the concentration of the nano aluminum hydroxide crystal seeds into the solution component tank to obtain Al₂O₃Calculated as 3.0g/100mL, Al₂(SO₄)₃The concentration of the nano aluminum hydroxide crystal seeds added into the solution component tank is Al₂O₃The amount was 2.0g/100 mL.

Heating the raw material tanks and the first impinging stream microreactor by microwaves, heating the raw material tanks and the first impinging stream microreactor to 80 ℃, starting booster pumps of the two component tanks, injecting an alkaline material and an acidic material into the first impinging stream reactor through the booster pumps, controlling the flow rate of the alkaline material to be 30mL/min, adjusting the pH value in the impinging stream reactor to be 8.3, carrying out a neutralization and precipitation reaction, and allowing a reaction mixed solution to stay in the first impinging stream microreactor for 1.5min and then enter a second microreactor; heating the reaction temperature of the second microreactor to 110 ℃ by adopting microwave heating, starting a booster pump of the second microreactor, injecting an acidic material into the second microreactor, controlling the pH value to be 5.0, and allowing a reaction mixed solution to stay in the second microreactor for 3.0min and then enter a third microreactor; heating the reaction temperature of the third microreactor to 50 ℃ by adopting microwave heating, starting a booster pump of the third microreactor, injecting an alkaline material into the third microreactor, controlling the pH value to be 10.7, and allowing a reaction mixed solution to stay in the third microreactor for 11min and then enter a fourth microreactor; heating the fourth microreactor to 100 ℃ by adopting microwave heating, starting a booster pump of the fourth microreactor, injecting an acidic material into the fourth microreactor, controlling the pH value to be 3.8, and allowing a reaction mixed solution to stay in the fourth microreactor for 4.0min and then enter a fifth microreactor; heating the fifth microreactor to 60 ℃ by adopting microwave heating, starting a booster pump of the fifth microreactor, injecting an alkaline material into the fifth microreactor, controlling the pH value to be 8.9 for aging reaction, aging the reaction mixed liquid in the fifth microreactor for 12min, then feeding the reaction mixed liquid into a product collecting tank, filtering the product, drying the product at 120 ℃ for 3h, roasting the product at 600 ℃ for 3h to obtain a hydrogenation catalyst C, and measuring the particle size distribution and the pore structure of the hydrogenation catalyst C as shown in Table 1.

Example 5

NaAlO with the concentration of 170g/100mL₂Solution and alkaline active metal solution B4 (MoO)₃: 56.5g/100 mL; NiO: 11.2g/100 mL) of alkaline material and Al in a concentration of 120g/100mL₂(SO₄)₃Solution and acidic active Metal solution A4 (MoO)₃: 69.7g/100 mL; NiO: 13.5g/100 mL) of an acidic material was added to the respective component tank and nano-aluminum hydroxide seed crystals, wherein NaAlO, were added to the component tank connected to the first microreactor₂Adding the concentration of the nano aluminum hydroxide crystal seeds into the solution component tank to obtain Al₂O₃Calculated as 2.4g/100mL, Al₂(SO₄)₃The concentration of the nano aluminum hydroxide crystal seeds added into the solution component tank is Al₂O₃The amount was 3.6g/100 mL.

Heating the raw material tanks, the first impinging stream microreactor and other microreactors by microwaves, heating the raw material tanks and the first impinging stream microreactor to 95 ℃, starting booster pumps of the two component tanks, injecting an alkaline material and an acidic material into the first impinging stream reactor through the booster pumps, controlling the flow rate of the alkaline material to be 27mL/min, adjusting the pH value in the impinging stream reactor to be 8.8, performing neutralization and precipitation reaction, and allowing a reaction mixed solution to stay in the first impinging stream microreactor for 1.8min and then enter a second microreactor; heating the reaction temperature of the second microreactor to 125 ℃ by adopting microwave heating, starting a booster pump of the second microreactor, injecting an acidic material into the second microreactor, controlling the pH value to be 3.9, and allowing a reaction mixed solution to stay in the second microreactor for 3.8min and then enter a third microreactor; heating the reaction temperature of the third microreactor to 75 ℃ by adopting microwave heating, starting a booster pump of the third microreactor, injecting an alkaline material into the third microreactor, controlling the pH value to be 10.7, and allowing a reaction mixed solution to stay in the third microreactor for 12min and then enter a fourth microreactor; heating by microwave to raise the reaction temperature of the fourth microreactor to 115 ℃, starting a booster pump of the fourth microreactor, injecting an acidic material into the fourth microreactor, controlling the pH value to be 3.6, and allowing a reaction mixed solution to stay in the fourth microreactor for 4.5min and then enter a fifth microreactor; heating the fifth microreactor to 65 ℃ by adopting microwave heating, starting a booster pump of the fifth microreactor, injecting an alkaline material into the fifth microreactor, controlling the pH value to be 8.4 for aging reaction, aging the reaction mixed liquid in the fifth microreactor for 14min, then feeding the reaction mixed liquid into a product collecting tank, filtering the product, drying the product at 120 ℃ for 3h, roasting the product at 600 ℃ for 3h to obtain a hydrogenation catalyst D, and measuring the particle size distribution and the pore structure of the hydrogenation catalyst D, wherein the particle size distribution and the pore structure are shown in Table 1.

Comparative example 1

The comparative example was prepared using a conventional batch process.

Heating the temperature of the reaction tank to 150 ℃, adding 23g of nano aluminum hydroxide seed crystal, adjusting the stirring speed to 200rad/min, and adding NaAlO with the concentration of 120g/100mL at the flow rate of 25mL/min₂The solution and the alkaline material of the alkaline active metal solution B4 were added to the reaction tank, and Al was added to the reaction tank at a concentration of 110g/100mL₂(SO₄)₃The pH value of the solution and the acidic material of the acidic active metal solution A4 is adjusted to 8.1, after 25min of stabilization, the acidic material with the concentration of 50g/100mL is added to adjust the pH value to 3.1, after 25min of stabilization, the alkaline material with the concentration of 40g/100mL is added to adjust the pH value to 11.0, after 25min of stabilization, the acidic material with the concentration of 55g/100mL is added to adjust the pH value to 8.2, after 3.0h of aging, the hydrogenation catalyst E is obtained after filtering and drying at 120 ℃ for 3h and roasting at 600 ℃ for 3h, and the particle size distribution and the pore structure are measured and shown in Table 1.

Comparative example 2

The comparative example employs five microreactors in series, which are the same as those in example 4, and the specific process is as follows: NaAlO with the concentration of 170g/100mL₂Alkaline substance of solution and alkaline active metal solution B4The material and Al with the concentration of 120g/100mL₂(SO₄)₃The solution and the acidic material of the acidic active metal solution A4 are added into respective component tanks, and nano aluminum hydroxide seed crystal is added into the component tank connected with the first microreactor, wherein NaAlO₂Adding the concentration of the nano aluminum hydroxide crystal seeds into the solution component tank to obtain Al₂O₃Calculated as 1.7g/100mL, Al₂(SO₄)₃The concentration of the nano aluminum hydroxide crystal seeds added into the solution component tank is Al₂O₃The amount was 2.4g/100 mL.

Heating each raw material tank, the first microreactor and other reactors by microwave, heating the raw material tanks and the first impinging stream microreactor to 120 ℃, starting booster pumps of the two component tanks, simultaneously feeding an alkaline material and an acidic material into the first microreactor, controlling the flow rate of the alkaline material to be 27mL/min, adjusting the pH value in the microreactor to be 8.8 and the reaction temperature to be 120 ℃, performing neutralization and precipitation reaction, and allowing a reaction mixed solution to stay in the first microreactor for 1.8min and then feeding the reaction mixed solution into the second microreactor; the reaction temperature of the second microreactor is 120 ℃, a booster pump of the second microreactor is started, the acidic material is injected into the second microreactor, the pH value is controlled to be 3.9, and the reaction mixed liquid stays in the second microreactor for 3.8min and then enters a third microreactor; the reaction temperature of the third microreactor is 120 ℃, a booster pump of the third microreactor is started, an alkaline material is injected into the third microreactor, the pH value is controlled to be 10.7, and the reaction mixed liquid stays in the third microreactor for 12min and then enters a fourth microreactor; the reaction temperature of the fourth microreactor is 120 ℃, a booster pump of the fourth microreactor is started, acidic materials are injected into the fourth microreactor, the pH value is controlled to be 3.6, and reaction mixed liquid stays in the fourth microreactor for 4.5min and then enters a fifth microreactor; and (3) starting a booster pump of the fifth microreactor when the reaction temperature of the fifth microreactor is 120 ℃, injecting an alkaline material into the fifth microreactor, controlling the pH value to be 8.4 for aging reaction, aging the reaction mixed liquid in the fifth microreactor for 14min, then feeding the reaction mixed liquid into a product collecting tank, filtering the product, drying the product at 120 ℃ for 3h, roasting the product at 600 ℃ for 3h to obtain a hydrogenation catalyst F, and measuring the particle size distribution and the pore structure of the hydrogenation catalyst F shown in Table 1.

TABLE 1 Properties of hydrogenation catalysts prepared in examples and comparative examples

Hydrogenation catalyst	A	B	C	D	E	F
							Specific surface area, m²/g	245	243	250	239	175	198
Pore volume, mL/g	1.50	1.47	1.46	1.49	1.12	1.25
							Several pore diameters, nm	45.2	39.5	40.3	42.1	20.3	25.7
MoO₃，wt%	45.0	44.7	43.9	44.2	45.0	43.7
							NiO，wt%	5.6	6.7	5.8	6.2	6.7	5.8
Particle size distribution of%
							＜100μm	4.9	4.7	4.6	5.0	44.5	32.7
100～150μm	85.6	86.7	87.2	86.4	52.1	62.9
							＞150μm	9.5	8.6	8.2	8.6	3.4	4.4
Pore size distribution%
							＜25nm	5.0	5.1	5.1	5.2	50.1	32.5
25～50nm	85.1	85.2	86.3	85.4	47.2	50.7
							＞50nm	9.9	9.7	8.6	9.4	2.7	16.8

TABLE 2 catalyst weight content of surface-phase active metal oxide to weight content of bulk-phase active metal oxide

	A	B	C	D	E	F
							Watch phase I_MoPhase/bulk phase I_Mo	20.3	20.1	19.9	19.8	8.5	12.1
Watch phase I_NiPhase/bulk phase I_Ni	9.7	9.8	9.5	9.4	3.1	4.9

As can be seen from the data in tables 1 and 2, the hydrogenation catalyst prepared by the method has the particle size centralized distribution of 100-150 μm, the hydrogenation catalyst obtained by the method has the advantages of high specific surface area, large pore volume and pore diameter, centralized distribution of the pore diameter of 25-50 nm, and high dispersion of the surface-phase active metal in the hydrogenation catalyst, and is very suitable for preparing macroporous hydrogenation catalysts such as residual oil hydrogenation protective agents.

Example 6

The catalyst activity evaluation experiment was performed on a 100mL autoclave apparatus, and the catalyst was presulfided prior to activity evaluation. The total reaction pressure of the catalyst is 15.5MPa, and the volume ratio of hydrogen to oil is 800: 1, the reaction temperature is 380 ℃, the reaction time is 2 hours, activity evaluation is carried out, and the properties of the raw oil and the evaluation results are respectively shown in tables 3-4.

TABLE 3 Properties of the feedstock.

Raw oil	Rare residual oil
		Density (20 ℃ C.), g.cm^-3	0.998
Carbon residue in wt%	5.45
		S，wt%	3.54
N，µg·g^-1	1498

TABLE 4 evaluation results of catalyst Activity

	A	B	C	D	E	F
							Relative desulfurization activity	162	155	152	157	100	123
Relative denitrification activity	147	148	150	142	100	118
							Relative demetallization activity	137	138	136	140	100	123

As can be seen from the data in Table 4, the catalyst prepared by the method of the present invention has high desulfurization, denitrification and demetalization activities under the same process conditions.

Claims

1. A boiling bed hydrogenation catalyst, the catalyst is a bulk phase catalyst, comprising alumina and active metal components, characterized in that: the grain size distribution of the fluidized bed hydrogenation catalyst is as follows: the crystal grains with the grain size of <100 mu m account for 1 to 5 percent of the total number of the hydrogenation catalyst crystal grains, the crystal grains with the grain size of 100 to 150 mu m account for 85 to 90 percent of the total number of the hydrogenation catalyst crystal grains, and the crystal grains with the grain size of >150 mu m account for 5 to 10 percent of the total number of the hydrogenation catalyst crystal grains;

the fluidized bed hydrogenation catalyst is prepared by adopting the following method: the adopted reaction system comprises N microreactors which are connected in series, and a first microreactor, a second microreactor, … … and an Nth microreactor are respectively arranged along the material flow direction, wherein the first microreactor adopts an impinging stream reactor, and the method comprises the following steps:

(1) respectively preparing an alkaline material and an acidic material;

2. The ebullated bed hydrogenation catalyst of claim 1 wherein: the properties of the ebullated bed hydrogenation catalyst are as follows: the specific surface area is 200-250 m²The pore volume is 1.3-1.5 mL/g, and the pore size distribution is as follows: diameter of hole<25nm ofThe pore volume of the pores is 5-10% of the total pore volume, the pore volume of the pores with the diameter of 25-50 nm is 85-95% of the total pore volume, and the pore volume of the pores with the diameter of more than 50nm is 5-10% of the total pore volume.

3. The ebullated bed hydrogenation catalyst of claim 1 wherein: in the fluidized bed hydrogenation catalyst, the active metal is calculated by oxide, the content of VIII group metal is 5-15 wt%, the content of VIB group metal is 30-50 wt%, and the content of alumina is 35-65 wt%; the VIII group active metal is selected from one or more of Ni and Co, and the VIB group active metal is selected from one or more of Mo and W.

4. The ebullated bed hydrogenation catalyst of claim 3 wherein: the VIII metal content is 5.0wt% -10.0 wt%, the VIB metal content is 30wt% -45 wt%, and the alumina content is 45wt% -65 wt%.

5. The ebullated bed hydrogenation catalyst of claim 1 wherein: according to the fluidized bed hydrogenation catalyst, active metal components are calculated by oxides, the weight content ratio of active metals of a surface phase VIII group to active metals of a bulk phase VIII group is 5.0: 1-11.0: 1, and the weight content ratio of active metals of a surface phase VIB to active metals of a bulk phase VIB is 10.0: 1-25.0: 1.

6. The ebullated bed hydrogenation catalyst of claim 5 wherein: according to the fluidized bed hydrogenation catalyst, active metal components are calculated by oxides, the weight content ratio of active metals of a surface phase VIII group to active metals of a bulk phase VIII group is 8.0-11.0: 1, and the weight content ratio of active metals of a surface phase VIB to active metals of a bulk phase VIB is 14.0: 1-21.0: 1.

7. The method for preparing an ebullated-bed hydrogenation catalyst according to claim 1, characterized in that: the adopted reaction system comprises N microreactors which are connected in series, and a first microreactor, a second microreactor, … … and an Nth microreactor are respectively arranged along the material flow direction, wherein the first microreactor adopts an impinging stream reactor, and the method comprises the following steps:

(1) respectively preparing an alkaline material and an acidic material;

8. The method of claim 7, wherein: in the fluidized bed hydrogenation catalyst, the active metal is calculated by oxide, the content of VIII group metal is 5-15 wt%, the content of VIB group metal is 30-50 wt%, and the content of alumina is 35-65 wt%; the VIII group active metal is selected from one or more of Ni and Co, and the VIB group active metal is selected from one or more of Mo and W.

9. The method of claim 8, wherein: in the fluidized bed hydrogenation catalyst, the active metal is calculated by oxide, the content of VIII group metal is 5.0wt% -10.0 wt%, the content of VIB group metal is 30wt% -45 wt%, and the content of alumina is 45wt% -65 wt%.

10. The method of claim 7, wherein: in the alkaline material in the step (1), the alkaline aluminate is selected from NaAlO₂And KAlO₂One or two of them, the concentration of the alkaline aluminate aqueous solution is Al₂O₃The amount is 20-200 g/100 mL; the concentration of the alkaline active metal aqueous solution is calculated by active metal oxides, the content of VIII group active metal oxides is 10-30 g/100mL, and the content of VIB group active metal oxides is 40-120 g/100 mL; in the acidic material, the acidic aluminum salt is selected from AlCl₃、Al₂(SO₄)₃And Al (NO)₃)₃One or more of the above, the concentration of the acidic aluminum salt aqueous solution is Al₂O₃The amount is 20-200 g/100 mL; the concentration of the acidic active metal aqueous solution is calculated by active metal oxides, the content of VIII group active metal oxides is 10-30 g/100mL, and the content of VIB group active metal oxides is 40-120 g/100 mL.

11. The production method according to claim 7, wherein N microreactors are connected in series, and N is an integer of not less than 5.

12. The process according to claim 11, wherein N microreactors are connected in series, and N is an integer of 5 to 11.

13. The process according to claim 11, wherein N microreactors are connected in series, and N is an integer of 5 to 7.

14. The method of claim 7, wherein: the specific process of pH value swing in the step (3) is as follows:

the mixed solution of the reaction products obtained in the step (2) enters a second micro reactor, and simultaneously, an acid material is introduced into the second micro reactor, so that the reaction system swings to the acid side; and the reaction product mixed solution obtained by the second microreactor enters a third microreactor, and simultaneously, an alkaline material is introduced into the third microreactor, so that the reaction system swings … towards the alkaline side, the obtained reaction product mixed solution sequentially enters a fourth microreactor to an N-1 microreactor, and the reaction system repeatedly swings towards the acid side and towards the alkaline side.

15. The method of claim 7, wherein: the first micro reactor is provided with two feed inlets for respectively introducing alkaline materials and acidic materials, the alkaline materials and the acidic materials enter the impinging stream micro reactor and then are communicated through a jet orifice, the alkaline material jet orifice and the acidic material jet orifice impact at a certain angle, and the impacting angle is 150-180 degrees.

16. The method of claim 7, wherein: the first micro-reactor and the rest micro-reactors are heated by microwave radiation.

17. The method of claim 7, wherein: introducing nano aluminum hydroxide seed crystals or mixing the nano aluminum hydroxide seed crystals with an acidic material and/or an alkaline material and then introducing the nano aluminum hydroxide seed crystals or the acidic material and/or the alkaline material into the first microreactor independently; the grain size distribution of the nano aluminum hydroxide seed crystal is as follows:<5nm crystal grains account for 5-15% of the total number of the aluminum hydroxide crystal grains, 5-15 nm crystal grains account for 80-85% of the total number of the aluminum hydroxide crystal grains,>the number of 15nm crystal grains accounts for 10-15% of the total number of the aluminum hydroxide crystal grains, and the adding amount of the nano aluminum hydroxide crystal seeds is Al₂O₃Counting the amount of Al which is added as the alkaline material and the acidic material in the first micro-reactor₂O₃1 to 5 percent of the total amount.

18. The method of claim 7, wherein: the precipitation reaction in the step (2) has the following reaction conditions: the reaction temperature is 50-150 ℃, and the pH value is 8.0-9.0; the diameter of an inner tube of the first micro-reactor is 10-20 mm, and the residence time of materials is controlled to be 1-5 min.

19. The method of claim 18, wherein: the precipitation reaction in the step (2) has the following reaction conditions: the reaction temperature is 50-120 ℃, the diameter of an inner tube of the first micro-reactor is 10-15 mm, and the residence time of materials is controlled to be 1-2 min.

20. The method of claim 7, wherein: in the step (2), introducing an alkaline material and an acidic material into a first microreactor, and introducing the alkaline material and the acidic material in an atomization or liquid mode; the flow rate of the alkaline material is 10-50 mL/min.

21. The method of claim 20, wherein: the flow rate of the alkaline material is 15-30 mL/min.

22. The production method according to claim 7 or 18, characterized in that: in the step (3), when the reaction system is oscillated to the alkali side, the reaction conditions are controlled as follows: the reaction temperature is 20-30 ℃ lower than that of the first microreactor, and the pH value is 10.0-11.0; the diameter of an inner pipe of the micro reactor is 5-10 mm larger than that of the adjacent micro reactor, and the residence time of materials in the micro reactor is controlled to be 8-15 min;

in the step (3), when the reaction system is oscillated to the acid side, the reaction conditions are controlled as follows: the reaction temperature is 20-30 ℃ higher than that of the first microreactor, and the pH value is 3.0-5.0; the diameter of an inner pipe of the micro reactor is 1-10 mm larger than that of an adjacent micro reactor, and the residence time of materials in the micro reactor is controlled to be 2-5 min.

23. The method of claim 22, wherein: in the step (3), when the reaction system swings to the alkali side, the diameter of an inner pipe of the micro reactor is 8-10 mm larger than that of the adjacent micro reactor, and the residence time of materials in the micro reactor is controlled to be 10-15 min;

in the step (3), when the reaction system swings to the acid side, the diameter of an inner pipe of the micro reactor is 2-3 mm larger than that of the adjacent micro reactor, and the residence time of materials in the micro reactor is controlled to be 3-5 min.

24. The method of claim 7, wherein: in the step (4), the aging reaction conditions are as follows: the aging temperature is 20-30 ℃ lower than that of the first microreactor, the pH value is 8.0-9.0, and the pH value is regulated and controlled by adopting the alkaline material or the acidic material prepared in the step (1) or other acidic or alkaline substances; the pipe diameter of the Nth micro-reactor is 5-10 mm larger than that of the Nth-1 micro-reactor, and the residence time in the Nth micro-reactor is 8-15 min.

25. The method of claim 24, wherein: the pipe diameter of the Nth micro-reactor is 5-10 mm larger than that of the Nth-1 micro-reactor, and the residence time in the Nth micro-reactor is 10-15 min.

26. The method of claim 7, wherein: in the step (4), the drying conditions are as follows: drying for 3-10 hours at 60-150 ℃; the roasting conditions are as follows: roasting at 450-650 deg.C for 2-15 hours.