CN107913742B

CN107913742B - Alumina carrier containing macropores and preparation method thereof

Info

Publication number: CN107913742B
Application number: CN201610884041.0A
Authority: CN
Inventors: 常晓昕; 王廷海; 张忠东; 李景锋; 姚文君; 李自夏; 高源�; 向永生; 吴杰; 王书峰; 黄德华
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2016-10-10
Filing date: 2016-10-10
Publication date: 2020-07-14
Anticipated expiration: 2036-10-10
Also published as: CN107913742A

Abstract

The invention relates to an alumina carrier containing macropores, which has the pore size distribution of 60-200 nm, the proportion of the macropores of 0.1-80 percent and the pore volume of 0.8-2.3 ml/g, wherein the carrier uses one or more of high-molecular sodium polyacrylate, ammonium polyacrylate and polyacrylic acid as a pore-expanding agent. The alumina carrier containing macropores has the characteristics of adjustable pore size and effectively controllable proportion of macropores.

Description

Alumina carrier containing macropores and preparation method thereof

Technical Field

The invention relates to an alumina carrier containing macropores and a preparation method thereof, in particular to an alumina carrier with adjustable macropore aperture and concentrated aperture distribution and a preparation method thereof.

Background

Petroleum and its products are used as main energy sources and raw material sources of daily chemicals and the like, and support the economic development of the whole country. The catalytic process and the reaction are indispensable components in the petroleum processing process, and the development of the high-efficiency catalyst is always a common pursuit of researchers in order to improve the conversion efficiency in the petroleum processing process. In order to improve the conversion efficiency of the catalyst, macroporous catalyst support materials are widely used for improving the performance of the catalyst from the viewpoint of improving the mass transfer rate.

The alumina is used as a traditional catalyst carrier material, has the characteristics of mature technology, adjustable pore structure, low use cost and easy processing and forming, and is widely used for preparing oil refining chemical catalysts. The carrier is used as an important component of the catalyst, so that the dispersion effect of the active component can be improved, and the pore structure of the carrier provides a diffusion channel for reactant molecules and product molecules, so that the utilization efficiency of the metal is improved. The macroporous carrier material has the characteristics of small mass transfer resistance and high efficiency, and in recent years, the carrier is used as a core component of the catalyst, and alumina, a molecular sieve, activated carbon and the like with a macroporous structure are widely researched to improve the service efficiency of the catalyst. Macroporous materials can be divided into two categories according to the synthesis process: one is to directly synthesize a new carrier material with a macroporous structure in the synthesis process, and the other is to obtain the carrier material with the macroporous structure by post-modifying the material. The research aiming at the second type macroporous carrier material synthesis method mainly obtains the macroporous structure by template agent, hydrothermal method and other methods, has the advantages of simple production process and lower cost, and the related treatment technology is already applied in industry.

The method for synthesizing the macroporous alumina material by the template method has many related documents, and can be divided into the following steps according to different types of templates: hard template agent and soft template agent. Good macroporous alumina can be obtained by a hard template agent method represented by activated carbon, and US4448896 discloses that carbon black is used as a pore-expanding agent to obtain a pore size distribution of 15-300nm, but it is difficult to prepare macroporous alumina with concentrated pore size distribution because of non-uniform particle diameter distribution of carbon black. CN201410347665.X discloses a preparation method of macroporous, high-strength alumina, which comprises adding pore-enlarging agent such as polyacrylamide, polyvinyl alcohol, alkyl cellulose, sesbania powder, starch, etc., to obtain macroporous alumina carrier, wherein the usage amount of the pore-enlarging agent accounts for 10-30% of alumina, but no specific pore diameter range is disclosed. Although a good macroporous alumina carrier can be obtained by the hard template method, the dosage of the template is preferably more than 20 percent, so that the processing cost is greatly increased, and the decomposition of a large amount of templates does not meet the development requirement of low carbon and environmental protection. CN 201010509425.7 discloses a method for co-pore-enlarging of hydrothermal and template agent, which is used for preparing an alumina carrier containing a macroporous structure, wherein the dosage of the template agent can be reduced to 3-10% through auxiliary pore-enlarging effect of hydrothermal, but the auxiliary hydrothermal causes the increase of energy consumption. CN 200310103035.X discloses a preparation method of macroporous alumina, which adopts polyvinyl alcohol, polypropylene alcohol, polyethylene glycol soft template agent to make hole expansion, and adds 1% polyethylene glycol, and the pore volume whose pore diameter is greater than 100nm is 26.2% of total pore volume. The soft template agent has the advantages of low dosage and good hole expanding effect, but the alcohol soft template agent with higher molecular weight has poorer solubility in water, so that the application of the alcohol soft template agent in expanding macroporous alumina is limited. CN201410148773.4 discloses a preparation method of alumina porous microspheres, which comprises the following steps: 1) dissolving a surfactant in deionized water, and stirring to obtain a water phase; 2) mixing a chelating agent, an alumina precursor and n-octanol, and stirring to obtain an oil phase; 3) adding Span80 and a pore-forming agent into the oil phase, and stirring; 4) pouring the clear oil phase obtained in the step 3) into the water phase, and continuously stirring and emulsifying; 5) and 4) carrying out vacuum filtration on the product obtained in the step 4), washing the obtained filter cake, and drying to obtain the alumina porous microspheres. The metal porous microsphere with the internally closed macroporous structure is obtained by utilizing a pore-foaming agent and a sol-gel process in emulsion, wherein the size of the metal porous microsphere is 1-100 mu m. The porous microspheres are prepared by utilizing the phase separation principle. The internal closed pore diameter is 50 nm-5 mu m. The pore-forming agent is polyvinylpyrrolidone,Polyacrylamide or polyacrylic acid. The invention uses a large amount of surfactants, chelating agents and pore-forming agents, and has the advantages of more raw materials and complex synthesis process. CN201310748661.8 discloses a preparation method of an alumina/carbon aerogel composite material, which is to dissolve a water-soluble carbohydrate compound and a water-soluble polymer in water in a closed container, then add aluminum salt or aluminum hydroxide, react at 140-300 ℃, dry and calcine at 300-1500 ℃ in an inert atmosphere to obtain the alumina/carbon aerogel composite material. The alumina/carbon aerogel composite material with low density and high porosity is prepared by adopting a one-pot method, has the advantages of easily obtained raw materials, simple preparation process, low cost and the like, is light in weight and high in porosity, and can be used for catalyst carriers, gas sensitive elements, solid electrolytic diaphragms, molten steel oxygen probe materials and the like. CN201310499233.6 discloses a preparation method of an alumina carrier, which comprises the following steps: firstly, carrying out neutralization reaction on an alkaline precipitant aqueous solution and an acidic aluminum salt aqueous solution to obtain a precipitation slurry; then adding water-soluble resin into the precipitation slurry and carrying out aging treatment on the precipitation slurry by adopting microwave heating; and finally, filtering, washing, drying and molding the aged mixture to obtain the final alumina carrier. The alumina carrier prepared by the method has larger aperture and concentrated pore distribution, particularly the proportion of 10-20 nm pores to the total pore volume is large and reaches 60-80%, and the alumina carrier is suitable for serving as a carrier of a heavy oil hydrogenation catalyst. CN201310258011.5 relates to a tooth spherical alumina carrier, a tooth spherical alumina hydrotreating catalyst and a preparation method thereof, which comprises the following components: 0.5-4 parts of peptizing agent; 0.2-2 parts by weight of a lubricant; 0.2-3 parts of dispersant; 0.3-4 parts of pore-expanding agent; 100 parts of aluminum hydroxide. The pore-expanding agent is one or a mixture of polyvinyl alcohol, sodium polyacrylate, starch derivatives or carbon black. The invention adds the anionic surfactant to reduce the adding amount of various auxiliary components and increase the specific surface area by 246m²Per g, pore-expanding agent sodium polyacrylate. The tooth-spherical alumina carrier of the invention not only saves the content of various auxiliary agents such as peptizing agent, pore-expanding agent, dispersing agent, anionic surfactant and the like, but also greatly reduces the content of the componentsThe cost is reduced, and the advantages of large specific surface area, high mechanical strength and the like are achieved. The invention uses peptizing agent, lubricant, dispersant, pore-expanding agent and other reagents, and the prepared alumina carrier has unimodal pore distribution.

CN201110170283.0 discloses a three-dimensional ordered macroporous alumina and a preparation method thereof. The three-dimensional ordered macroporous alumina has a macroporous diameter of 50-1000 nm, a particle size of 1-50 mm and a mechanical strength of 80-280 g/mm. The method comprises the following steps: adding a carbohydrate compound and concentrated sulfuric acid into the monodisperse polymer microsphere emulsion to obtain a modified polymer microsphere colloidal crystal template, then filling alumina sol, and aging and roasting to obtain the three-dimensional ordered macroporous alumina. The method can greatly improve the adhesion of alumina precursors, enhance the mechanical strength of the material, ensure that the macroporous material is not easy to be broken into fine powder when the template is removed by high-temperature roasting, and still can keep higher integrity. CN201110116418.5 provides mesoporous spherical alumina and a method for preparing the mesoporous spherical alumina by adopting a template agent for guidance. The method is characterized in that an oil column forming method is adopted, a template agent with a guiding function is added into the aluminum sol in the process of preparing the aluminum sol, and a large amount of mesoporous structures are manufactured in the alumina spheres due to the existence of the template agent with the guiding function in the forming and aging processes of the aluminum sol. The template agent is an organic monomer or a linear polymer, and the organic monomer is one of acrylic acid, ammonium acrylate, acrylamide and allyl alcohol. The specific surface of the mesoporous spherical alumina is 150-300 m²The particles have a diameter of 0.1-5 mm, a pore volume of 0.7-1.5 ml/g, pores with a diameter of 2-40 nm of more than 97%, and a bulk density of 0.30-0.80 g/cm³The crushing strength is 70 to 250N/grain. The mesoporous spherical alumina prepared by the template agent has more concentrated pore diameter, and can be used as a catalyst or a catalyst carrier in petrochemical industry and fine chemical industry. CN 201010221302.3(CN102311134A) discloses a spherical integral macroporous alumina and a preparation method thereof. The method comprises the following steps: mixing polymer microsphere emulsion, alumina sol and coagulant at a certain ratio, dispersing the mixture in oil phase to form W/O type droplets, and heating the mixed phaseThe system is to make the alumina sol in the water phase gel into spheres, then separate the formed gel microspheres from the oil phase, and then obtain the spherical integral macroporous alumina after aging, drying and roasting in ammonia water medium. The alumina has the advantages of uniform and controllable macropore diameter within the range of less than 1 mu m, controllable size of spherical particles, higher mechanical strength, simple and easy forming process and convenient mass preparation. The diameter of the polymer microsphere is 50-1000 nm, and the types of the polymer microsphere are polystyrene microsphere, poly n-butyl benzoate microsphere, polyacrylate microsphere and other ester microspheres. The coagulant is hexamethylenetetramine and urea. The oil phase is organic hydrocarbon. The invention mainly prepares integral macroporous alumina, and the macropores have uniform and controllable aperture. The preparation process uses lipid microsphere and coagulant. The preparation process is complex, and the used reagent raw materials are more. The polymer microspheres are used, so that the structure of the inner pore channel of the alumina carrier is closed pores, namely the inner pore channel of the alumina carrier has no penetrability. CN200910204238.5(CN102040235) discloses a three-dimensional ordered macroporous alumina and a preparation method thereof. The method comprises the following steps: assembling monodisperse polymer microspheres into a colloidal crystal template, filling alumina sol prepared by a specific method into the template, and finally drying and roasting to obtain the macroporous alumina. The method can well control the compounding process of the aluminum sol and the polymer microspheres, and the network structure of the aluminum oxide gel is not damaged as far as possible, so that the prepared aluminum oxide not only has three-dimensional ordered macroporous channels, but also has higher specific surface area. The invention forms small window holes by moderate sintering of the template, and makes the big holes in the material communicate with the surrounding big holes through 12 small window holes. The alumina of the invention is suitable for being used as a heavy oil catalyst carrier and an adsorption separation material of organic macromolecules. When the catalyst is applied to a catalyst carrier material, the mass transfer capacity of materials in the catalyst can be improved, and the activity and the selectivity of the catalyst can be improved. CN201410148773.4 discloses a preparation method of alumina porous microspheres, which comprises the following steps: 1) dissolving a surfactant in deionized water, and stirring to obtain a water phase; 2) mixing chelating agent, alumina precursor and n-octanol, stirring,as an oil phase; 3) adding Span80 and a pore-forming agent into the oil phase, and stirring; 4) pouring the clear oil phase obtained in the step 3) into the water phase, and continuously stirring and emulsifying; 5) and 4) carrying out vacuum filtration on the product obtained in the step 4), washing the obtained filter cake, and drying to obtain the alumina porous microspheres. The microsphere has an internally closed macroporous structure, the size of the microsphere is 1-100 mu m, and the internal closed pore diameter is 50-5 mu m. The internal pore diameter of the alumina porous microsphere is closed, namely the internal pore channel of the alumina carrier has no penetration.

Macroporous alumina has been successfully applied to a plurality of catalyst systems, and has various improvements in the aspects of catalyst activity, selectivity and stability. Although the hard template agent can obtain a better macroporous structure, the hard template agent has certain defects in the aspect of adjusting the pore size, and the solubility of the polyvinyl alcohol soft template agent in water is influenced by the degree of polymerization, so that the preparation of the super-macroporous alumina is limited to a certain extent.

Disclosure of Invention

Aiming at the wide application of macroporous alumina in the field of catalysis, the invention adopts one or more of high molecular sodium polyacrylate, ammonium polyacrylate and polyacrylic acid as pore-enlarging agent to synthesize the macroporous alumina carrier. The macroporous alumina has the characteristics of adjustable aperture and effectively controllable proportion of macropores. The alumina carrier containing macropores can be used in the fields of petrochemical industry and fine chemical industry.

The invention provides an alumina carrier containing macropores, the pore size distribution is 60-200 nm, preferably 80-180 nm, the proportion of the macropores is 1-80%, preferably 10-80%, the pore volume is 0.8-2.3 ml/g, preferably 0.8-1.2 ml/g or preferably 1.8-2.3 ml/g, and the inner pore channels of the alumina carrier have connectivity. The carrier uses one or more of macromolecule sodium polyacrylate, ammonium polyacrylate and polyacrylic acid as pore-enlarging agent. The pore-expanding agent is preferably a mixture of ammonium polyacrylate and sodium polyacrylate or a mixture of ammonium polyacrylate and polyacrylic acid, wherein the mass ratio of the ammonium polyacrylate to the sodium polyacrylate or the polyacrylic acid is 1-10: 1. the mixture of the ammonium polyacrylate and the sodium polyacrylate or the polyacrylic acid is used as a pore-expanding agent, and the alumina carrier is easier to generate macropores, and the pore size distribution is more concentrated and is 120-200 nm.

The pore diameter of the alumina carrier containing macropores can be adjusted by changing the molecular weight of the pore-expanding agent, the mass ratio of the ammonium polyacrylate to the sodium polyacrylate or the polyacrylic acid and the addition amount. The pore size distribution can vary from 60 to 200nm, such as 60 to 200nm, 60 to 90nm, 140 to 180nm, 120 to 200nm, and the like. The proportion of the macropores is 0.1-80%, and can be adjusted to 10-80%, 20-80% and the like.

The invention also provides a preparation method of the macroporous alumina carrier, which comprises the steps of firstly, carrying out acidification treatment on the pore-expanding agent, namely preparing an acid solution containing the pore-expanding agent, then adding the pseudo-boehmite powder and sesbania powder into a kneader to be uniformly mixed, then adding the acid solution containing the pore-expanding agent into the pseudo-boehmite powder to be uniformly kneaded, wherein the adding amount of the acid solution containing the pore-expanding agent is 0.1-10 wt% of the pseudo-boehmite, preferably 0.5-5.0 wt%, and carrying out strip extrusion, molding, drying and roasting to obtain the macroporous alumina carrier.

The preparation process of the acid solution containing the pore-expanding agent is as follows: the method comprises the steps of heating deionized water to 25-95 ℃, dissolving acid into the deionized water, adding a pore-expanding agent, and completely dissolving to obtain an acid solution containing the pore-expanding agent. The pore-expanding agent is subjected to acidification treatment, the dispersibility of the pore-expanding agent is good, the problem that alumina particles are easy to agglomerate is effectively solved, and after extrusion, molding, drying and roasting, the particle size of the powder is more uniform and the molding effect is good.

The addition amount of the acid is 2-8 wt%, preferably 3-5 wt% of the pseudo-boehmite, and the acid used is various organic or inorganic acids commonly used in the field, such as acetic acid, citric acid, nitric acid, hydrochloric acid and the like. The addition amount of the sesbania powder is 0.2-8 wt% of the pseudo-boehmite. The source and property of the pseudo-boehmite powder are not limited, and the pseudo-boehmite powder can be a product produced by a carbonization method, a nitric acid method, a sulfuric acid method, an ammonium method and other processes. Is suitable for pseudo-boehmite with different ranges of specific surface area, pore volume and pore diameter.

The kneading or extruding process comprises the steps of adding the prepared acid solution containing the pore-expanding agent into sesbania powder and pseudo-boehmite, uniformly mixing, extruding, forming, drying for 2-8 hours at 80-200 ℃, and roasting for 4-6 hours at 550-700 ℃, thus finally obtaining the macroporous alumina carrier.

In order to ensure that the alumina carrier has better performance and is applied to the FCC gasoline hydrodesulfurization catalyst as a carrier, the alumina carrier is preferably introduced with auxiliary agents of boron, potassium and strontium, and the specific process comprises the following steps: firstly, acidizing a pore-expanding agent, namely preparing an acid solution containing the pore-expanding agent, then adding pseudo-boehmite powder and sesbania powder into a kneader to be uniformly mixed, and then adding an aqueous solution containing boric acid, potassium nitrate and strontium nitrate; and then adding an acid solution containing a pore-expanding agent into the pseudo-boehmite powder, kneading uniformly, wherein the addition amount of the acid solution containing the pore-expanding agent is 0.1-10 wt%, preferably 0.5-5.0 wt% of the pseudo-boehmite, and carrying out extrusion, molding, drying and roasting to obtain the alumina carrier modified by the aid of the potassium and strontium. The composition of the carrier is calculated by the mass of oxides: comprises 93-99 wt% of alumina, 0.1-2.5 wt% of boron, 0.1-2.5 wt% of potassium and 0.1-3.5 wt% of strontium.

Through the modification of the additives of boron, potassium and strontium, the carrier is prepared into a hydrodesulfurization catalyst, such as a cobalt-molybdenum catalyst, so that the acidity of the hydrodesulfurization catalyst can be adjusted, the polymerization of olefin in raw oil can be reduced, the carbon deposition inactivation in the catalyst can be inhibited, the carbon deposition rate is low, and the hydrogenation stability of the hydrodesulfurization catalyst is improved.

The alumina carrier modified by the additives of boron, potassium and strontium is further improved, the potassium and the strontium are preferably used for carrying out surface modification on the carrier containing the additives of boron, potassium and strontium, and the specific process comprises the following steps: preparing a potassium nitrate and strontium nitrate-containing aqueous solution as an impregnation carrier, and drying and roasting to obtain the composite carrier with the surface modified by the aid of potassium and strontium. The content of the composite carrier potassium oxide and strontium is controlled in the range of 0.1-2.5 wt% and 0.1-3.5 wt%, respectively.

After the surface of the alumina carrier is modified by potassium and strontium, the concentration difference is formed between the concentration of potassium and strontium on the surface of the carrier and the concentration of potassium and strontium in the carrier, the content of potassium and strontium on the surface of the carrier is higher than that of potassium and strontium in the carrier, namely the molar content or the mass content of potassium and strontium on the surface of the carrier can be 1.2-2.5 times of that of potassium and strontium in the carrier. The carrier is prepared into the hydrodesulfurization catalyst, the specific surface area of the hydrodesulfurization catalyst can be improved, the inactivation of carbon deposit on the surface of the hydrodesulfurization catalyst is inhibited, the dispersion degree and the adhesion of active components such as cobalt and molybdenum on the carrier of the hydrodesulfurization catalyst are improved, and the active components such as cobalt and molybdenum are not easy to lose, so that the problem of activity reduction caused by the loss of the active components such as cobalt and molybdenum is effectively solved.

Compared with the prior art, the invention does not need to add reagents such as coagulant, dispersant, chelating agent and the like, and the preparation cost is greatly reduced. The pore-expanding agent sodium polyacrylate, ammonium polyacrylate, polyacrylic acid and the like belong to high molecular polymers, so that the solubility of the pore-expanding agent sodium polyacrylate, ammonium polyacrylate, polyacrylic acid and the like in water is higher, and the molecular volume of the pore-expanding agent sodium polyacrylate, ammonium polyacrylate, polyacrylic acid and the like expands hundreds of times after absorbing water, so that the dosage of the pore-expanding agent sodium polyacrylate, ammonium polyacrylate, polyacrylic acid and the like can be reduced to a certain extent, and the. In addition, the high molecular weight sodium polyacrylate, ammonium polyacrylate, polyacrylic acid and the like are used as pore-enlarging agents, and the molecular weight can be adjusted from thousands to tens of millions according to different polymerization degrees, so that the sodium polyacrylate, the ammonium polyacrylate and the polyacrylic acid are used as the pore-enlarging agents, and the pore size can be adjusted according to the molecular weight. The pore-expanding agent sodium polyacrylate, ammonium polyacrylate and polyacrylic acid have a coil structure, so that the pore passage in the carrier has a through property instead of a closed pore structure. The prepared alumina carrier contains a macroporous structure and a mesoporous structure, wherein the mesoporous range is 5-50 nm, the mesoporous proportion is 20-70%, and the mesoporous proportion is preferably 20-50%, and the alumina carrier is an alumina carrier containing meso-macropores. And the pore size is not a uniform pore size structure.

Drawings

FIG. 1 is a graph showing the pore size distribution of the alumina carrier containing macropores prepared in example 4.

Detailed Description

The present invention is described in further detail below by way of examples, which should not be construed as limiting the invention thereto.

The main raw material sources for preparing the catalyst are as follows: the raw material reagents used in the invention are all commercial products.

Example 1

240m L of deionized water is measured by a beaker, 12.0g of nitric acid with the concentration of 68 percent is added into the deionized water to be uniformly mixed, the mixture is placed in a water bath kettle at the temperature of 80 ℃, 6.0g of sodium polyacrylate with the molecular weight of million is weighed and added into the prepared nitric acid solution of the deionized water, and the mixture is stirred and completely dissolved to obtain the acid solution containing the sodium polyacrylate.

Weighing 300g of pseudo-boehmite powder and 15.0g of sesbania powder, uniformly mixing, adding an acid solution of sodium polyacrylate into the pseudo-boehmite and the sesbania powder, and kneading and extruding to form a clover shape. Drying at 120 deg.C for 8 hr, and calcining at 650 deg.C for 4 hr to obtain macroporous alumina carrier A-1. The specific surface area and pore size distribution of the macroporous alumina support are shown in Table 1.

Example 2

Preparation method of acid solution of polyacrylic acid as pore-expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that million-grade sodium polyacrylate is replaced by million-grade polyacrylic acid to obtain the macroporous alumina carrier A-2. The specific surface area and pore size distribution of the macroporous alumina support are shown in Table 1.

Example 3

Preparation method of acid solution of ammonium polyacrylate as pore-expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that million-grade sodium polyacrylate is replaced by hundred thousand-grade ammonium polyacrylate to obtain the macroporous alumina carrier A-3. The specific surface area and pore size distribution are shown in Table 1.

Example 4

The method of formulating the acid solution of the cell expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that million-grade sodium polyacrylate is replaced by million-grade ammonium polyacrylate and hundred thousand-grade sodium polyacrylate, and the mass ratio of the ammonium polyacrylate to the sodium polyacrylate is 2:1 to obtain the macroporous alumina carrier A-4. The specific surface area and pore size distribution are shown in Table 1. FIG. 1 is a graph showing the pore size distribution of alumina support A-4. As can be seen from fig. 1, the prepared alumina carrier has a structure with bimodal pore distribution.

Example 5

Preparation method of acid solution of pore-expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that million-grade sodium polyacrylate is replaced by million-grade polyacrylic acid and hundred thousand-grade ammonium polyacrylate, and the mass ratio of the ammonium polyacrylate to the polyacrylic acid is 8:1, so that the macroporous alumina carrier A-5 is obtained. The specific surface area and pore size distribution are shown in Table 1.

Example 6

Preparation method of acid solution of pore-expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that million-grade sodium polyacrylate is replaced by million-grade sodium polyacrylate and million-grade ammonium polyacrylate, and the mass ratio of the ammonium polyacrylate to the sodium polyacrylate is 5:1, so that the macroporous alumina carrier A-6 is obtained. The specific surface area and pore size distribution are shown in Table 1.

Example 7

Preparation method of acid solution of pore-expanding agent, kneading-extruding, drying and baking were carried out as in example 1. Except that the million-grade sodium polyacrylate is replaced by the million-grade sodium polyacrylate and the million-grade polyacrylic acid, and the mass ratio of the sodium polyacrylate to the polyacrylic acid is 3:1, so that the macroporous alumina carrier A-7 is obtained. The specific surface area and pore size distribution are shown in Table 1.

TABLE 1 macroporous alumina Supports specific surface area and pore size distribution

	Specific surface area，m²/g	Total pore volume, ml/g	Large pore volume, ml/g	Pore size of macropores, nm	Pore diameter of mesoporous, nm
						A-1	279.8	1.66	0.86	89	23
A-2	278.7	1.51	0.95	143	15
						A-3	273.8	1.84	1.16	65	41
A-4	276.1	1.69	1.29	132	9
						A-5	276.4	1.71	0.71	158	47
A-6	279.8	2.03	0.78	187	31
						A-7	273.1	1.64	1.13	124	27

Example 8

300g of pseudo-boehmite powder and 15.0g of sesbania powder are weighed and mixed evenly, and 1.89g of boric acid, 2.3g of potassium nitrate and 1.66g of strontium nitrate are respectively weighed and completely dissolved in 60g of distilled water to prepare the aqueous solution containing boron, potassium and strontium. Then adding into the mixture of pseudo-boehmite powder and sesbania powder. Adding an acid solution of sodium polyacrylate into pseudo-boehmite and sesbania powder, and kneading and extruding to form a clover shape. Drying at 120 deg.C for 8 hr, and calcining at 650 deg.C for 4 hr to obtain the modified alumina carrier A-8 with potassium and strontium as assistants.

Preparing cobalt nitrate and ammonium molybdate into impregnation liquid, adding ammonia water to adjust the pH value to completely dissolve salt, impregnating the alumina carrier A-8, drying at 130 ℃ for 5 hours, and roasting at 600 ℃ for 7 hours to obtain the hydrodesulfurization catalyst C-1. Catalyst C-1 mainly consists of: 2.5 wt% of cobalt oxide, 9.5 wt% of molybdenum oxide and 9.5 wt% of aluminum oxide carrier A-888.

Example 9

An alumina carrier A-8 modified by auxiliary agents of potassium and strontium is prepared by using potassium and strontium. The specific process for carrying out the surface modification comprises the following steps: preparing aqueous solution containing potassium nitrate and strontium nitrate as impregnation liquid, respectively weighing 3.1g of potassium nitrate and 3.4g of strontium nitrate, completely dissolving in 30ml of distilled water, diluting with deionized water to prepare the impregnation liquid to impregnate the alumina carrier A-8, and drying and roasting to obtain the alumina composite carrier A-9 with the surface modified by the aid of potassium and strontium.

Preparing cobalt nitrate and ammonium molybdate into an impregnation solution, adding ammonia water to adjust the pH value to completely dissolve salt, impregnating an alumina carrier A-9, drying at 130 ℃ for 5 hours, and roasting at 650 ℃ for 5 hours to obtain the hydrodesulfurization catalyst C-2. Catalyst C-2 mainly consists of: 2 wt% of cobalt oxide, 8.5 wt% of molybdenum oxide and 8. 989.5 wt% of alumina carrier A.

Hydrodesulfurization catalysts C-1 and C-2 were charged in a 10ml fixed bed adiabatic reactor, respectively, to evaluate the catalyst reaction performance. The catalyst is presulfided with a sulfur oil ofStraight run gasoline with vulcanizing agent CS₂At a concentration of 1.0 wt%; the vulcanization pressure is 3.0MPa, the hydrogen-oil volume ratio is 350, and the volume space velocity of the vulcanized oil is 3.0h^-1The vulcanization procedure is vulcanization treatment at 230 ℃ and 270 ℃ for 5 hours. After the vulcanization treatment is finished, the whole fraction FCC gasoline is switched to be subjected to displacement treatment for 6 hours, and after the pre-vulcanization process is finished, the reaction process conditions are adjusted to carry out catalytic cracking gasoline reaction. The reaction process conditions are as follows: the temperature of the reactor is 250 ℃, the reaction pressure is 1.4MPa, and the volume space velocity is 3h^-1Hydrogen to oil volume ratio 280. Samples were taken for analysis after about 50h of reaction. The desulfurization rates of products of hydrodesulfurization catalysts C-1 and C-2 are respectively 83 percent and 84 percent, the olefin reduction amount is respectively 1.9 percent and 1.6 percent, the octane number loss is respectively 0.4 unit and 0.3 unit, the octane number loss of the hydrodesulfurization catalyst is low, the desulfurization rate is high, and the activity of the catalyst is good. The catalyst is subjected to stability inspection, the reaction is carried out for 300h, the desulfurization rates of products of hydrodesulfurization catalysts C-1 and C-2 are respectively 81% and 83%, the octane number loss is respectively 0.3 unit and 0.2 unit, the carbon deposition rate is 2.2, the catalyst has stable reaction performance, active components are not easy to lose, and the carbon deposition rate is low, so that the hydrodesulfurization stability is good.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.

Claims

1. The alumina carrier containing macropores is characterized in that the pore size distribution of the alumina carrier is 60-200 nm, the proportion of the macropores is 1-80%, the pore volume is 0.8-2.3 ml/g, the alumina carrier also contains a mesoporous structure, the pore size of the mesopores is 5-50 nm, and the proportion of the mesopores is 20-70%; the alumina carrier uses one or more of high molecular sodium polyacrylate, ammonium polyacrylate and polyacrylic acid as pore-enlarging agent; the inner pore passage of the alumina carrier has penetrability; the alumina carrier is introduced with the auxiliary agents of boron, potassium and strontium, and the alumina carrier comprises the following components in mass percentage: comprises 93-99 wt% of alumina, 0.1-2.5 wt% of boron, 0.1-2.5 wt% of potassium and 0.1-3.5 wt% of strontium; the mass content of potassium and strontium on the surface of the alumina carrier is 1.2-2.5 times of the content of potassium and strontium in the carrier; the preparation method of the alumina carrier containing macropores comprises the following steps: firstly, acidizing a pore-expanding agent to obtain an acid solution containing the pore-expanding agent, then adding pseudo-boehmite powder and sesbania powder into a kneader to be uniformly mixed, and then adding an aqueous solution containing boric acid, potassium nitrate and strontium nitrate; then adding an acid solution containing a pore-expanding agent into the pseudo-boehmite powder, kneading uniformly, wherein the addition amount of the acid solution containing the pore-expanding agent is 0.1-10 wt% of the pseudo-boehmite, and carrying out extrusion-molding-drying-roasting to obtain an alumina carrier modified by using the additives of boron, potassium and strontium; and then preparing an alumina carrier which is used as an impregnation liquid and is modified by the aid of potassium and strontium for impregnation, and drying and roasting to obtain the composite carrier which is surface-modified by the aid of potassium and strontium.

2. The alumina carrier containing macropores according to claim 1, wherein the pore size distribution of the alumina carrier is 80 to 180 nm.

3. The alumina carrier containing macropores according to claim 1, wherein the proportion of macropores of the alumina carrier is 10 to 80%.

4. The alumina carrier containing macropores according to claim 1, wherein the alumina carrier has a pore volume of 0.8 to 1.2ml/g or 1.8 to 2.3 ml/g.

5. The alumina carrier with macropores according to claim 2, wherein the proportion of mesopores is 20-50%.

6. The macroporous alumina carrier as claimed in claim 1, wherein the pore-enlarging agent is a mixture of ammonium polyacrylate and sodium polyacrylate, or a mixture of ammonium polyacrylate and polyacrylic acid.

7. The alumina carrier containing macropores according to claim 6, wherein the mass ratio of ammonium polyacrylate to sodium polyacrylate or polyacrylic acid in the pore-expanding agent is 1-10: 1.

8. the alumina carrier containing macropores according to claim 4, wherein the pore size distribution of the alumina carrier is 120 to 200 nm.