Alumina carrier and its preparation method and application

Abstract

The application belongs to the field of catalysts, and particularly relates to an alumina carrier and a preparation method and application thereof. The surface of the alumina carrier has oxygen-containing groups, the density of the oxygen-containing groups on the surface of the alumina carrier is 0.15-5 mmol / m 2 ; wherein the oxygen-containing groups are at least one of hydroxyl, carboxyl and lactone groups; and the specific surface area of the alumina carrier is 10-150 m 2 / g. The types, quantity and density of the oxygen-containing groups on the surface of the obtained carrier are improved, which can well meet the requirements of various load-type catalysts in the field of petroleum chemical industry on the dispersion form and dispersion degree of different metal active components; and the carrier also has the characteristics of low bulk density, high water absorption, large pore volume and average pore diameter, which has a gain effect on the uniform distribution of active metal components in the catalyst loading process, and has extremely high application value.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and in particular relates to an alumina carrier and a preparation method and application thereof. Background Art

[0002] Alumina is widely used in the petrochemical industry as a carrier for supported catalysts due to its easy availability, low cost, and good thermal stability, corrosion resistance, wear resistance, and insulation. Industrial alumina carriers are generally obtained by molding alumina powders such as pseudo-boehmite powder and fast-de-alumina powder. Different types of reactions also have different requirements for the physical and chemical properties of alumina carriers. It is generally believed that the physical properties of the powder raw materials, molding aids, and molding parameters will affect the physical properties of the alumina carrier, such as pore volume, pore size, specific surface area, strength, thermal stability, acidity and alkalinity, and thus affect the performance of the catalyst prepared subsequently. There have been many related studies and reports on the regulation of the physical parameters of alumina carriers by optimizing the alumina powder refining process and alumina molding methods.

[0003] CN109420528A discloses a modified alumina carrier and a preparation method thereof. An alumina precursor is uniformly mixed with a furfuryl alcohol solution of a certain concentration, and then a peptizing agent is added and kneaded into a plastic body. The body is then formed, dried, and calcined to obtain an alumina carrier with uniform carbon distribution, high carbon content, high weak acid distribution, and high mechanical strength.

[0004] CN105983443A discloses a bimodal pore structure alumina carrier and a preparation method thereof. Hydrated alumina is mixed with synthetic cellulose, a boron-containing compound and a powdered polymer, molded and calcined to obtain an alumina carrier that can be used in the field of catalytic hydrogenation and has a bimodal pore structure, large pore volume and pore diameter, good mechanical strength and a simple preparation process.

[0005] CN115957821A discloses a γ-alumina carrier and a preparation method thereof. A hydrothermal method is used to combine a crown ether organic long chain with a soluble lanthanum salt to form a crown ether lanthanum organic ligand, which is uniformly grafted onto the surface of the pore structure of the γ-alumina material. The modified structure protects the surface hydroxyl groups, inhibits sintering and phase change, and reduces the damage to the microporous structure caused by high temperature. In addition, the organic ligand can reduce the cation vacancies in the γ-alumina structure and reduce the probability of interaction between anions and cation vacancies, so that the γ-alumina still has a stable crystal structure under high temperature environmental conditions.

[0006] The existing literature shows that the number or density of hydroxyl groups on the surface of alumina has an effect on the dispersion form and dispersion degree of the metal active component, for example, the literature (ACS Catalysis, 2023, 13, 4, 2277-2285) prepared three kinds of γ-Al2O3 carriers with different OH contents and OH densities by calcining the pseudoboehmite carrier at different temperatures, and found that the final dispersion degree of Ag on the surface of γ-Al2O3 depends on the OH content, and the dispersion speed depends on the OH density. The literature (Nature Communications, 2020, 11, 1, 529) found that the increase in the number of terminal hydroxyl groups of γ-Al2O3 can greatly improve the dispersion of Ag on its surface and even present monatomic dispersion.

[0007] The existing technical solutions have the problems of low number and low density of oxygen-containing groups on the surface of the alumina carrier, single type of oxygen-containing groups, and few methods and means for simultaneous regulation, resulting in low uniformity of the active metal distribution of the subsequently prepared catalyst, poor thickness controllability, and difficulty in meeting the requirements of high metal utilization, high performance, and long service life. At the same time, the preparation process of the alumina carrier is long and complex, and there is a problem of unstable properties of different batches of alumina carriers obtained under the same method and conditions.

[0008] Therefore, there is still a need to develop an alumina carrier with a simple preparation method, controllable and stable properties of surface oxygen-containing groups, and applicability to multiple types of catalytic reactions. SUMMARY

[0009] In view of the technical problems existing in the prior art, the purpose of the present application is to provide an alumina carrier and a preparation method and application thereof. The inventors of the present application found through research that by adding inorganic carbon species to alumina and then subjecting it to at least one of heat treatment (different from calcination), crystallization, oxidation, alkalization, and irradiation treatment, the surface of the alumina can have hydroxyl groups and also contain other oxygen-containing groups in addition to hydroxyl groups. The obtained carrier has improved types, number, and density of surface oxygen-containing groups, can well meet the various index requirements of different metal active component dispersion form and dispersion degree for various supported catalysts in the petroleum and chemical industry field, and also has the characteristics of low bulk density, high water absorption, large pore volume, and large average pore size, which has a gain effect on the uniform distribution of active metal components during the catalyst loading process and has extremely high application value.

[0010] The first aspect of the present application is to provide an alumina carrier, wherein the surface of the alumina carrier has oxygen-containing groups, and the density of the oxygen-containing groups on the surface of the alumina carrier is 0.15-5 mmol / m 2 ; wherein the oxygen-containing groups are at least one of hydroxyl groups, carboxyl groups, and lactone groups; the specific surface area of the alumina carrier is 10-150 m 2 / g, preferably 15-80 m2 / g.

[0011] In a preferred embodiment of the present invention, the specific surface area of ​​the alumina carrier is preferably 15-80 m 2 / g, such as 15, 30, 40, 50, 60, 70, 80m 2 / g, and any two values ​​or any interval between any two values.

[0012] In a preferred embodiment of the present invention, the content of the hydroxyl group is 3-60 mmol / g.

[0013] In a preferred embodiment of the present invention, the content of the carboxyl group is 3-50 mmol / g.

[0014] In a preferred embodiment of the present invention, the content of the lactone group is 3-40 mmol / g.

[0015] According to a preferred embodiment of the present invention, the content of the hydroxyl group is 3-60 mmol / g, the content of the carboxyl group is 3-50 mmol / g; and the content of the lactone group is 3-40 mmol / g.

[0016] According to the present invention, the technical effect of regulating the amount of oxygen-containing groups on the surface of alumina can be achieved by adopting the preparation method of the present invention. When the alumina carrier is subsequently used as a catalyst carrier, it can achieve an increase in the dispersion of the loaded metal and a diversification of the coordination form, thereby improving and enhancing the catalyst reaction performance. Due to the differences in properties of different oxygen-containing groups, their effects on the dispersion and catalytic performance of the metal are also inconsistent. There is no unified understanding of the interaction between different oxygen-containing groups and metal precursors and the size of the metal particles. Generally speaking, the stronger the "anchoring" effect of the carrier on the metal particles, the higher its dispersion, but the metal may be coated or coordinated too stably by the carrier, causing its adsorption activation ability for the reactant molecules to be significantly weakened or disappear, and the catalytic performance instead decreases. Therefore, for some catalysts, it is not the case that the higher the metal dispersion, the better the catalytic performance. In the present invention, the alumina carrier can be specifically regulated and matched according to the subsequent required preparation of the catalyst and the reaction that needs to be adapted.

[0017] According to a preferred embodiment of the present invention, the density of oxygen-containing groups on the surface of the alumina support is preferably 0.3-3 mmol / m 2 , such as 0.3, 0.5, 1, 1.5, 2, 2.5, 3 mmol / m 2 , and any two values ​​or any interval between any two values.

[0018] According to a preferred embodiment of the present invention, the content of hydroxyl group is 3-60 mmol / g, for example, 3, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 mmol / g, and any two values ​​or any interval between any two values.

[0019] According to a preferred embodiment of the present invention, the content of the carboxyl group is 3-50 mmol / g, for example 3, 10, 15, 20, 25, 30, 35, 40, 45, 50 mmol / g, and any two values ​​or any interval between any two values.

[0020] According to a preferred embodiment of the present invention, the content of the lactone group is 3-40 mmol / g, for example, 3, 10, 15, 20, 25, 30, 35, 40 mmol / g, and any two values ​​or any interval between any two values.

[0021] In a preferred embodiment of the present invention, the alumina support contains alumina and optionally an inorganic compound other than alumina.

[0022] According to the present invention, the inorganic compound can be selected from a wide range. In a preferred embodiment of the present invention, the inorganic compound is preferably selected from at least one of silicon oxide, magnesium oxide, barium oxide, calcium oxide, and hydrotalcite.

[0023] According to the present invention, the mass ratio of the inorganic compound to the aluminum oxide can be selected within a wide range. In a preferred embodiment of the present invention, the mass ratio of the inorganic compound to the aluminum oxide is (0-30):100, preferably (0-28):100, for example, 0, 5, 10, 15, 20, 23, 28, and the ratio of any two values ​​or any interval between any two values ​​to 100.

[0024] In a preferred embodiment of the present invention, the alumina carrier has at least one of the following characteristics: the water absorption rate of the alumina carrier is 50%-200%; and / or the strength of the alumina carrier is 30-200Nm; and / or the bulk density of the alumina carrier is 0.4-0.8g / ml; and / or the pore volume of the alumina carrier is 0.6-1.5ml / g.

[0025] The detection method of the above characteristics of the alumina carrier in the present invention can adopt the detection method described in the specific implementation method section, including but not limited to the detection method in the specific implementation method section.

[0026] In a preferred embodiment of the present invention, the alumina support contains alumina and carbide.

[0027] In a preferred embodiment of the present invention, based on 100 wt% of the total weight of the alumina carrier, the content of the alumina is 50-98 wt%.

[0028] In a preferred embodiment of the present invention, the alumina support is prepared by the following preparation method, which comprises:

[0029] The raw materials including alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species and an optional inorganic compound other than alumina are granulated and surface-treated to obtain the alumina support;

[0030] Wherein, the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment;

[0031] The heat treatment conditions include: the heat treatment atmosphere includes a first atmosphere and a second atmosphere, the first atmosphere is selected from at least one of carbon dioxide, water vapor, acetylene, ethylene, and methane, and the second atmosphere is selected from at least one of air, nitrogen, argon, and helium, the volume ratio of the first atmosphere to the second atmosphere is (0.05-1):1, the heat treatment temperature is 300-1200°C, the heat treatment time is 1-24h, and the pressure is 0.1-3MPa; the oxidation is oxidation by an oxidant.

[0032] The second aspect of the present invention is to provide a method for preparing an alumina carrier, the preparation method comprising:

[0033] The raw materials including alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species and an optional inorganic compound other than alumina are granulated and surface-treated to obtain the alumina support;

[0034] Wherein, the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment;

[0035] The heat treatment conditions include: the heat treatment atmosphere includes a first atmosphere and a second atmosphere, the first atmosphere is selected from at least one of carbon dioxide, water vapor, acetylene, ethylene, and methane, and the second atmosphere is selected from at least one of air, nitrogen, argon, and helium, the volume ratio of the first atmosphere to the second atmosphere is (0.05-1):1, the heat treatment temperature is 300-1200°C, the heat treatment time is 1-24h, and the pressure is 0.1-3MPa; the oxidation is oxidation by an oxidant.

[0036] In a preferred embodiment of the present invention, the preparation method comprises the following steps:

[0037] (1) mixing alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species, and optionally an inorganic compound other than alumina to obtain a mixed dry material;

[0038] (2) kneading the mixed dry materials into a shape and extruding them into granules;

[0039] (3) Drying the product of step (2) and performing the surface treatment to obtain the alumina carrier.

[0040] In a preferred embodiment of the present invention, the alumina powder includes pseudo-boehmite powder and optionally other alumina powders other than boehmite powder. By way of example, the other alumina powders other than boehmite powder include, but are not limited to, one or more of the following: γ-alumina, η-alumina, θ-alumina, χ-alumina, hydrated alumina having a diaspore structure, hydrated alumina having a gibbsite structure, and hydrated alumina having a Bayerite structure.

[0041] In a preferred embodiment of the present invention, the molding agent is selected from at least one of polyethylene glycol cellulose, methyl cellulose, carboxymethyl cellulose, sodium hydroxymethyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose, and starch.

[0042] In a preferred embodiment of the present invention, the pore-forming agent is selected from at least one of polyvinyl alcohol, polyethylene glycol, polyacrylamide, polypropylene glycol, and sesbania powder.

[0043] In a preferred embodiment of the present invention, the inorganic compound is at least one selected from silicon oxide, magnesium oxide, barium oxide, calcium oxide, and hydrotalcite.

[0044] According to the present invention, the amount of each raw material can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the inorganic carbon species is 1-40 parts by mass relative to 100 parts of alumina powder, for example, 1, 3, 5, 8, 10, 15, 20, 25, 30, 35, 40 parts, and any two values ​​or any interval between any two values; and / or,

[0045] In parts by mass, the amount of the forming agent is 1-15 parts, for example, 1, 3, 5, 8, 10, 15 parts, or any two parts or any interval between any two parts, relative to 100 parts of alumina powder; and / or

[0046] In parts by mass, relative to 100 parts of alumina powder, the amount of the pore former is 1-15 parts, for example, 1, 3, 5, 8, 10, 15 parts, and any two values ​​or any interval between any two values, and / or,

[0047] In parts by mass, relative to 100 parts of alumina powder, the amount of the inorganic compound is 0-30 parts, preferably 0-28 parts, such as 0, 5, 10, 15, 20, 23, 28 parts, and any two values ​​or any interval between any two values.

[0048] More preferably, the amount of the inorganic carbon species is 1-40 parts by mass relative to 100 parts of alumina powder; the amount of the forming agent is 1-15 parts by mass relative to 100 parts of alumina powder; the amount of the pore-forming agent is 1-15 parts by mass relative to 100 parts of alumina powder; the amount of the inorganic compound is 0-30 parts by mass relative to 100 parts of alumina powder, preferably 0-28 parts.

[0049] In a preferred embodiment of the present invention, the crystallization conditions include: 120-250° C., 4-18 h, 0.2-15 MPa, and / or the solvent is selected from at least one of water, ethanol, ethylene glycol, and ethylenediamine.

[0050] In a preferred embodiment of the present invention, the oxidation conditions include: 30-80° C., 0.2-10 h, the oxidant is selected from at least one of nitric acid, sulfuric acid, ammonium persulfate, hydrogen peroxide, potassium permanganate, and ascorbic acid, and the concentration of the oxidant is 0.1-10 mol / L.

[0051] In a preferred embodiment of the present invention, the alkalization conditions include: 30-110° C., 0.2-10 h, the alkaline compound is selected from at least one of sodium hydroxide, sodium bicarbonate, sodium carbonate, sodium acetate, sodium oxalate, sodium citrate, potassium hydroxide, potassium bicarbonate, potassium carbonate, potassium acetate, and potassium citrate, and the concentration of the alkaline compound is 0.1-10 mol / L.

[0052] In a preferred embodiment of the present invention, the irradiation radiation source is selected from gamma rays and / or microwaves; preferably: the gamma ray irradiation dose rate is 2-90 kGy / min, the time is 0.2-24 h; and / or, the microwave power is 50-1000 W; the time is 0.5-60 min.

[0053] In a preferred embodiment of the present invention, the inorganic carbon species is selected from at least one of coke, activated carbon, carbon black, white carbon, glassy carbon, charcoal, bamboo charcoal, coconut shell charcoal, graphene, graphyne, and diamond.

[0054] According to the present invention, the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment.

[0055] The inventors of the present invention have discovered through research that the surface treatment methods can be combined in the following ways to obtain an alumina carrier with a higher hydroxyl content and a higher total content of oxygen-containing groups: the surface treatment methods are selected from: heat treatment; or crystallization and oxidation; or heat treatment and irradiation treatment; or heat treatment and alkalization; or heat treatment, alkalization and irradiation.

[0056] The inventors of the present invention have further discovered through research that alumina supports with a further higher hydroxyl content and a further higher total oxygen-containing group content can be obtained by using specific surface treatment methods for different inorganic carbon species, as follows:

[0057] In a more preferred embodiment of the present invention, when the inorganic carbon species is coke, activated carbon, carbon black, white carbon, or glassy carbon, heat treatment is adopted; or, surface treatment is performed by crystallization and oxidation.

[0058] In a more preferred embodiment of the present invention, when the inorganic carbon species is charcoal, bamboo charcoal, or coconut shell charcoal, heat treatment is used; or, heat treatment and irradiation are used for surface treatment.

[0059] In a more preferred embodiment of the present invention, when the inorganic carbon species is graphene, graphyne, or diamond, the surface treatment is performed by crystallization and oxidation; or heat treatment and alkalization; or heat treatment, alkalization, and irradiation.

[0060] In a more preferred embodiment of the present invention, the solution used for kneading is an acidic solution. Preferably, the concentration of the acidic solution is 0.001-1 mol / L.

[0061] In a more preferred embodiment of the present invention, the solute in the acidic solution is selected from at least one of acetic acid, maleic acid, malic acid, citric acid, oxalic acid, formic acid, tartaric acid, ascorbic acid, salicylic acid, succinic acid, nitric acid, sulfuric acid, hydrochloric acid, hypochlorous acid, and phosphoric acid.

[0062] In a more preferred embodiment of the present invention, the solvent in the acidic solution is selected from water and / or a mixed solution of water and an organic matter; more preferably, the organic matter is selected from methanol, ethanol, and ethylene glycol, and the volume ratio of the organic matter to water is (0.05-1.5):1.

[0063] The third aspect of the present invention is to provide an application of the alumina carrier described in the first aspect, or the alumina carrier prepared by the preparation method described in the second aspect, in a catalyst.

[0064] In a more preferred embodiment of the present invention, the catalyst contains a metal element.

[0065] According to the above technical solution, the present invention introduces inorganic carbon species into the alumina support and adopts surface treatment, wherein the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment, wherein the heat treatment is carried out under specific conditions, and the oxidation is oxidation by an oxidant, which can cause the surface of the inorganic carbon species to undergo different degrees of oxidation (different from the strong oxidation by simple calcination), thereby increasing the hydroxyl content and the total number of oxygen-containing groups:

[0066] The alumina carrier of the present invention has oxygen-containing groups on its surface, and the density of oxygen-containing groups on the surface of the alumina carrier is 0.15-5 mmol / m 2 , preferably 0.3-3mmol / m 2 ;

[0067] The oxygen-containing group is at least one of a hydroxyl group, a carboxyl group, and a lactone group; the specific surface area of ​​the alumina carrier is 10-150 m 2 / g, preferably 15-80m 2 / g.

[0068] It can be seen that the alumina carrier of the present invention not only has a high content of oxygen-containing groups, but also has relatively excellent physical properties, which can meet the requirements of industrial catalysts for physical properties such as strength and specific surface area. The regulation of the number and distribution of oxygen-containing groups on the surface of the alumina carrier of the present invention can well meet the various index requirements of the dispersion form and dispersion degree of different metal active components of various supported catalysts in the petrochemical field. Its high water absorption rate, large pore volume and most probable pore diameter have a positive effect on the uniform distribution of active metal components during the catalyst loading process, and it has extremely high application value. DETAILED DESCRIPTION

[0069] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0070] Example 1

[0071] Take the specific surface area of ​​150.3m 2100g of pseudo-boehmite powder (with a pore volume of 0.75ml / g and a bulk density of 0.22g / ml), 5g of sesbania powder, 8g of carboxymethyl cellulose, and 4g of bamboo charcoal were mixed evenly. 1.8g of concentrated nitric acid was added to 150g of deionized water to prepare a mixed solution. The mixed solution was added to the mixed powders, and then the mixture was placed in a kneader and fully kneaded. After that, the mixture was extruded and pelletized to obtain cylindrical particles with a particle size of 2-4mm. The particles were dried at 80°C for 8h and then heat-treated with air and water vapor (volume ratio 0.8:1) at 1200°C and 0.1MPa for 24h to obtain alumina support S1.

[0072] Example 2

[0073] Take the specific surface area of ​​150.3m 2 / g, pore volume 0.75ml / g, bulk density 0.22g / ml 100g pseudo-boehmite powder, 10g silicon oxide, 8g coconut shell carbon, 5g sesbania powder, 10g ethyl cellulose, mixed evenly. Take 1.8g concentrated nitric acid and add it to 150g deionized water to prepare a mixed solution. Add the mixed solution to the mixed powder, put them into a kneader and knead them thoroughly, then extrude and shape them into pellets to obtain cylindrical particles with a particle size of 2-4mm. Then heat treat them with air and water vapor (volume ratio 0.8:1) at 600℃ and 1.5MPa for 12h to obtain alumina carrier S2.

[0074] Example 3

[0075] Take the specific surface area of ​​160.4m 2 / g, pore volume 0.8ml / g, bulk density 0.16g / ml 20g alumina trihydrate powder, 80g α-Al2O3 powder, 6g polyethylene glycol, 7g methyl cellulose, 10g graphene, mixed evenly. Take 4g oxalic acid and 4g acetic acid, add 150g deionized water, and prepare a mixed solution. Add the mixed solution to the mixed powder, put them into a kneader and knead them thoroughly, then extrude and shape them into pellets to obtain cylindrical particles with a particle size of 2-4mm, dry them at 80℃ for 8h, then crystallize them at 250℃, 15MPa for 4h, then soak them in a mixed solution of 5mol / L hydrogen peroxide and 5mol / L potassium permanganate at 30℃ for 0.2h, and freeze-dry them at -20℃ for 4h to obtain alumina carrier S3.

[0076] Example 4

[0077] Take the specific surface area as 200.3m 2 / g, pore volume 1.42ml / g, bulk density 0.15g / ml 100g alumina trihydrate powder, 5g polyethylene glycol cellulose, 5g polyvinyl alcohol, 12g graphyne, mixed evenly. Take 2.2g concentrated sulfuric acid, add 125g deionized water to prepare a mixed solution. The mixed solution is added to the mixed powder, and then put into a kneader to fully knead, and then extruded and granulated to obtain cylindrical particles with a particle size of 2-4mm, dried at 80℃ for 8h, heat treated at 300℃, 3MPa carbon dioxide and nitrogen (volume ratio 0.5:1) for 1h, and then immersed in 5mol / L potassium carbonate solution, and then irradiated with 2kGy / min of gamma rays for 24h to obtain alumina carrier S4.

[0078] Example 5

[0079] Take 120g of pseudo-boehmite powder (physical properties are the same as in Example 1), 20g of γ-Al2O3 powder, 10g of fast-dealumina powder, 4.5g of sesbania powder, 5g of starch, and 3.7g of carbon black and mix them evenly. Weigh 2.5g of concentrated hydrochloric acid and 1.2g of acetic acid, add them to 160g of deionized water to prepare a mixed solution. Add the mixed solution to the mixed powders, put them into a kneader and knead them thoroughly, then extrudate and granulate to obtain cylindrical particles with a particle size of 2-4mm, dry them at 80℃ for 8h, then crystallize them at 120℃ and 0.2MPa for 18h, then soak them in a mixed solution of 0.1mol / L nitric acid and 0.1mol / L hydrogen peroxide at 80℃ for 10h, and freeze-dry them at -40℃ for 8h to obtain the alumina carrier S5.

[0080] Example 6

[0081] Take 120g of pseudo-boehmite powder (physical properties are the same as in Example 1), 20g of γ-Al2O3 powder, 10g of barium oxide, 5.8g of cyanoethyl cellulose, 4.8g of polypropylene glycol, and 30g of diamond and mix them evenly. Weigh 6.9g of ascorbic acid and 1.2g of concentrated hydrochloric acid, add 175g of ethanol and deionized water (volume ratio 5:1) as a solvent to prepare a mixed solution. Add the mixed solution to the mixed powders, put them into a kneader and knead them thoroughly, then extrude and form pellets to obtain cylindrical particles with a particle size of 2-4mm, dry them at 100°C for 4h, heat treat them at 350°C, 0.2MPa of acetylene and argon (volume ratio 0.05:1) for 3h, then soak them in 0.1mol / L sodium hydroxide solution for 10h, and then irradiate them with 50W microwaves for 60min to obtain alumina carrier S6.

[0082] Example 7

[0083] Take 120g of pseudo-boehmite powder (physical properties are the same as those in Example 1), 20g of calcium oxide, 9g of polyethylene glycol cellulose, 10g of polyvinyl alcohol, 6g of glassy carbon and 5g of coke and mix them evenly. Take 1.8g of concentrated nitric acid and 2.2g of salicylic acid and add them to 150g of deionized water to prepare a mixed solution. Add the mixed solution to the mixed powders, and then put them into a kneader to fully knead them. Then, extrude and shape them into pellets to obtain cylindrical particles with a particle size of 2-4mm. Dry them at 80℃ for 8h, then crystallize them at 180℃ and 7.5MPa for 11h, and then soak them in a mixed solution of 2.5mol / L ammonium persulfate and 2.5mol / L ascorbic acid at 55℃ for 5h to obtain alumina carrier S7.

[0084] Example 8

[0085] Take the specific surface area as 200.3m 2 100g of alumina trihydrate powder with a pore volume of 1.42ml / g and a bulk density of 0.15g / ml, 1g of hydroxypropyl cellulose and 1g of polyacrylamide, 1g of charcoal and 1g of bamboo charcoal are mixed evenly. 3g of concentrated hydrochloric acid and 3g of hypochlorous acid are added to 85g of deionized water to prepare a mixed solution. The mixed solution is added to the mixed powders, and then placed in a kneader and fully kneaded. After that, the mixed solution is extruded and pelletized to obtain cylindrical particles with a particle size of 2-4mm. The particles are dried at 80℃ for 8h, then crystallized at 250℃ and 5MPa for 6h, and then immersed in a 5mol / L potassium bicarbonate and 5mol / L sodium bicarbonate solution for 0.2h to obtain the alumina support S8.

[0086] Example 9

[0087] Take the specific surface area as 200.3m 2 / g, pore volume 1.42ml / g, bulk density 0.15g / ml 100g alumina trihydrate powder, 1g hydroxypropyl cellulose and 1g polyacrylamide, 1g carbon black and 1g white carbon black are mixed evenly. Take 3g concentrated hydrochloric acid and 3g hypochlorous acid, add 85g deionized water to prepare a mixed solution. Add the mixed solution to the mixed powder, put them into a kneader and knead them thoroughly, then extrusion and pelletization to obtain cylindrical particles with a particle size of 2-4mm, dry at 80℃ for 8h, heat-treat at 1200℃, 3MPa methane and air (volume ratio 0.1:1) for 4h, and then irradiate with 500W microwave for 30min to obtain alumina carrier S9.

[0088] Comparative Example 1

[0089] Mix 100g of pseudo-boehmite powder (same properties as in Example 1), 5g of sesbania powder, 8g of carboxymethyl cellulose, and 4g of bamboo charcoal. Add 1.8g of concentrated nitric acid to 150g of deionized water to prepare a mixed solution. Add the mixed solution to the mixed powders, then knead them thoroughly in a kneader. Then, extrusion and pelletization are performed to produce cylindrical particles with a diameter of 2-4mm. After drying and air heat treatment (following the same sequence, temperature, pressure, and time as in Example 1), alumina support D1 is obtained.

[0090] Comparative Example 2

[0091] Mix 100g of pseudo-boehmite powder (physical properties similar to those in Example 2), 10g of silicon oxide, 5g of sesbania powder, and 10g of ethyl cellulose. Add 1.8g of concentrated nitric acid to 150g of deionized water to prepare a mixed solution. Add the mixed solution to the mixed powders, then knead them thoroughly in a kneader. Then, extrusion and pelletization are performed to obtain cylindrical particles with a diameter of 2-4mm. After drying and heat treatment (using the same sequence and conditions as in Example 2), the alumina support D2 is obtained.

[0092] Comparative Example 3

[0093] Take the specific surface area of ​​160.4m 2 / g, pore volume 0.8ml / g, and bulk density 0.16g / ml, 20g of alumina trihydrate powder, 80g of α-Al2O3 powder, 6g of polyethylene glycol, and 7g of methylcellulose were mixed uniformly. 4g of oxalic acid and 4g of acetic acid were added to 150g of deionized water to prepare a mixed solution. The mixed solution was added to the mixed powders, and then placed in a kneader and fully kneaded. After extrusion and pelletization, cylindrical particles with a particle size of 2-4mm were obtained. After drying, crystallization, and oxidation (in the same order and under the same conditions as in Example 3), alumina support D3 was obtained.

[0094] Comparative Example 4

[0095] Take the specific surface area as 200.3m 2 100g of alumina trihydrate powder with a pore volume of 1.42ml / g and a bulk density of 0.15g / ml, 5g of polyethylene glycol cellulose, and 5g of polyvinyl alcohol are mixed uniformly. 2.2g of concentrated sulfuric acid is added to 125g of deionized water to prepare a mixed solution. The mixed solution is added to the mixed powders, and then placed in a kneader and fully kneaded. After extrusion and pelletization, cylindrical particles with a particle size of 2-4mm are obtained. After drying, heat treatment, alkalization and irradiation (the order and conditions are the same as in Example 4), the alumina carrier D4 is obtained.

[0096] Comparative Example 5

[0097] Take 120g of pseudo-boehmite powder (physical properties are the same as in Example 1), 20g of γ-Al2O3 powder, 10g of barium oxide, 5.8g of cyanoethyl cellulose, and 4.8g of polypropylene glycol and mix them evenly. Weigh 6.9g of ascorbic acid and 1.2g of concentrated hydrochloric acid, add 175g of ethanol and deionized water (volume ratio 5:1) as a solvent to prepare a mixed solution. Add the mixed solution to the mixed powders, and then put them into a kneader to fully knead. Then, extrusion molding and pelletizing are obtained to obtain cylindrical particles with a particle size of 2-4mm. After drying, heat treatment and alkalization (in the same order and conditions as in Example 6), the alumina carrier D5 is obtained.

[0098] Comparative Example 6

[0099] Take the specific surface area as 200.3m 2 / g, pore volume 1.42ml / g, bulk density 0.15g / ml 100g alumina trihydrate powder, 1g hydroxypropyl cellulose and 1g polyacrylamide are mixed evenly. Take 3g concentrated hydrochloric acid and 3g hypochlorous acid, add 85g deionized water to prepare a mixed solution. The mixed solution is added to the mixed powder, and then put into a kneader and fully kneaded. After that, it is extruded and granulated to obtain cylindrical particles with a particle size of 2-4mm. It is dried at 80℃ for 8h, crystallized at 120℃ and 0.2MPa for 18h, and then soaked in a mixed solution of 0.1mol / L nitric acid and 0.1mol / L hydrogen peroxide at 80℃ for 10h, and then heat-treated at 1200℃ and 3MPa methane and air (volume ratio 0.1:1) for 4h, and then soaked in 5mol / L potassium bicarbonate and 5mol / L sodium bicarbonate solution for 0.2h and irradiated with 500W microwave for 30min to obtain alumina carrier D6.

[0100] Comparative Example 7

[0101] Take the specific surface area of ​​150.3m 2 100g pseudo-boehmite powder with a pore volume of 0.75ml / g and a bulk density of 0.22g / ml, 5g sesbania powder, 8g carboxymethyl cellulose, 3g bamboo charcoal, 3g coconut shell carbon, 3g graphene, 3g graphene, 3g carbon black, 3g diamond, 3g glassy carbon, 3g coke, 3g charcoal and 3g white carbon are mixed. 1.8g concentrated nitric acid is taken and added into 150g deionized water to prepare a mixed solution. The mixed solution is added to the mixed powder, and then put into a kneader together and fully kneaded. Extrusion molding and pelletizing are then carried out to obtain cylindrical particles with a particle size of 2-4mm. After drying and air heat treatment (sequence and temperature, pressure, time are the same as in Example 1), an alumina carrier D7 is obtained.

[0102] Test example

[0103] Physical property analysis of the carriers of the examples and comparative examples: The specific surface area of ​​the carriers was measured using the nitrogen physical adsorption BET method;

[0104] Weigh 50 mL of the carrier to determine the bulk density of the carrier (take the arithmetic mean of three measurements);

[0105] The pore volume and most probable pore diameter of the support were measured by mercury intrusion method.

[0106] The carrier strength was measured using a particle strength meter (the arithmetic mean of the measurement results of 30 carriers was taken); 50 g of alumina carrier was weighed and soaked in water for 15 minutes, and the water absorption rate of the carrier was measured after draining the surface free water. The results are shown in Table 1.

[0107] Analysis and Determination of Oxygen-Containing Groups in the Carriers of the Examples and Comparative Examples: The nature and quantity of oxygen-containing groups in the carriers were determined using the Boehm method. Three 0.6 g carrier samples were weighed and soaked in 40 ml of 0.05 mol / L NaHCO₃, Na₂CO₃, and NaOH solutions for 24 h. 10 ml of the soaked solution was titrated with 0.05 mol / L hydrochloric acid. Each sample was titrated three times, and the arithmetic mean was taken. The number of each oxygen-containing group in the carrier was calculated based on the alkali consumption. The oxygen-containing group density was calculated based on the carrier specific surface area data. The results are listed in Table 2.

[0108] Table 1. Physical property measurement results of alumina supports in Examples and Comparative Examples

[0109]

[0110] As can be seen in Table 1, the alumina support prepared using the method of the present invention exhibits an average particle strength greater than 45 Nm and a relatively low bulk density, demonstrating that this support is still suitable for most industrial catalyst loading requirements. Furthermore, for the same catalyst loading volume, less active component is used, which helps reduce catalyst costs. Furthermore, the alumina support of the Examples exhibits high water absorption, large pore volume, and large probable pore diameter, which enhances the uniform distribution of active metal components during catalyst loading.

[0111] Table 2. Measurement results of oxygen-containing groups on alumina supports of Examples and Comparative Examples

[0112]

[0113] As described in the background art, studies have shown that the number or density of hydroxyl groups on the surface of alumina affects the dispersion form and dispersion degree of metal active components. Increasing the number of terminal hydroxyl groups can greatly improve the dispersion of metal elements on the carrier surface and even achieve single-atom dispersion.

[0114] As can be seen from Table 2, the hydroxyl content in the surface of the alumina support in the present invention is significantly higher than that in the comparative example, all above 3mmol / g. Moreover, the total content of oxygen-containing groups such as hydroxyl, carboxyl and lactone groups in the surface of the alumina support of the present invention is significantly higher than that in the comparative example, which can improve the adsorption strength of the support surface to the metal precursor and provide more metal particle anchoring sites, thereby slowing down the agglomeration or growth trend of metal particles in the subsequent catalyst preparation process (such as impregnation, drying, reduction, etc.), and achieving high dispersion of metal elements on the support surface. It can be seen from this that the present invention introduces inorganic carbon species into the alumina support, and in combination with the subsequent surface treatment method, can significantly increase the total content of oxygen-containing groups, especially significantly increase the hydroxyl content.

[0115] As shown in Examples 1-9, the introduction of inorganic carbon species onto an alumina carrier, combined with a subsequent preferred treatment method, for example, the surface treatment method is selected from: heat treatment; or, crystallization and oxidation; or, heat treatment and irradiation treatment; or, heat treatment and alkalization; or, heat treatment, alkalization and irradiation, can significantly increase the total content of oxygen-containing groups, especially significantly increase the hydroxyl content.

[0116] From the comparison of Example 1, Example 2, and Example 8, it can be seen that when the inorganic carbon species is charcoal, bamboo charcoal, or coconut shell charcoal, heat treatment; or surface treatment by heat treatment and irradiation; can further increase the total content of oxygen-containing groups, especially significantly increase the hydroxyl content.

[0117] Generally speaking, the stronger the "anchoring" effect of the carrier on the metal particles, the higher the dispersion. However, the metal may be coated by the carrier or the coordination is too stable, which significantly weakens or eliminates its adsorption and activation ability for the reactant molecules, and the catalytic performance decreases. Therefore, for some catalysts, the higher the metal dispersion, the better the catalytic performance. As can be seen from the comparison of Example 5 and Example 9, when the inorganic carbon species is coke, activated carbon, carbon black, white carbon black, or glassy carbon, heat treatment, or crystallization and oxidation are more preferred embodiments for surface treatment.

[0118] Experimental verification shows that when the inorganic carbon species is coke, activated carbon, carbon black, white carbon, or glassy carbon, surface treatment is performed by heat treatment, or crystallization and oxidation; when the inorganic carbon species is graphene, graphyne, or diamond, surface treatment is performed by crystallization and oxidation, or heat treatment and alkalization, or heat treatment, alkalization, and irradiation, which can further increase the total content of oxygen-containing groups, especially significantly increase the hydroxyl content.

[0119] In summary, as can be seen from Table 2, the content and density of oxygen-containing groups on the surface of the alumina support prepared using the method of the present invention are significantly higher than those of the alumina support prepared in the comparative example. Furthermore, by adjusting the raw material ratio, preparation process parameters, and conditions, the method of the present invention can regulate the number and distribution of oxygen-containing groups on the surface of the alumina support, effectively meeting the various requirements for the dispersion form and degree of different metal active components of various supported catalysts in the petrochemical industry.

[0120] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

[0121] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of conflict, the definitions in this specification shall prevail.

[0122] When this specification uses the prefix "well known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, the objects introduced by the prefix include those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become generally recognized in the art to be suitable for similar purposes.

[0123] The endpoints and any values ​​of the ranges disclosed in this application document are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0124] In the context of this specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0125] Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas thus formed shall be deemed as part of the original disclosure or original record of the present invention, and shall not be regarded as new content that has not been disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. An alumina carrier having oxygen-containing groups on its surface, wherein the density of oxygen-containing groups on the surface of the alumina carrier is 0.15-5 mmol / m 2 ; in, The oxygen-containing group is at least one of a hydroxyl group, a carboxyl group, and a lactone group; the specific surface area of ​​the alumina carrier is 10-150m 2 / g; The alumina support is prepared by the following preparation method, which comprises: The raw materials including alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species and an optional inorganic compound other than alumina are granulated and surface-treated to obtain the alumina support; Wherein, the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment; The inorganic carbon species is selected from at least one of coke, activated carbon, carbon black, white carbon, glassy carbon, charcoal, bamboo charcoal, coconut shell charcoal, graphene, graphyne, and diamond.

2. The alumina carrier according to claim 1, characterized in that: The content of the hydroxyl group is 3-60 mmol / g; and / or, The content of the carboxyl group is 3-50 mmol / g; and / or, The content of the lactone group is 3-40 mmol / g.

3. The alumina carrier according to claim 1, characterized in that: The inorganic compound is selected from at least one of silicon oxide, magnesium oxide, barium oxide, calcium oxide and hydrotalcite; and / or, The mass ratio of the inorganic compound to the aluminum oxide is (0-30):

100.

4. The alumina carrier according to claim 1, characterized in that: The mass ratio of the inorganic compound to the aluminum oxide is (0-28):

100.

5. The alumina carrier according to claim 1, characterized in that: The water absorption rate of the alumina support is 50-200%; and / or, The strength of the alumina support is 30-200 Nm; and / or, The bulk density of the alumina support is 0.4-0.8 g / ml; and / or, The pore volume of the alumina carrier is 0.6-1.5 ml / g.

6. The alumina carrier according to any one of claims 1 to 5, characterized in that: The alumina support contains alumina and carbide; and / or, Based on the total weight of the alumina support being 100 wt%, the content of the alumina is 50-98 wt%; The heat treatment conditions include: the heat treatment atmosphere includes a first atmosphere and a second atmosphere, the first atmosphere is selected from at least one of carbon dioxide, water vapor, acetylene, ethylene, and methane, and the second atmosphere is selected from at least one of air, nitrogen, argon, and helium, the volume ratio of the first atmosphere to the second atmosphere is (0.05-1):1, the heat treatment temperature is 300-1200°C, the heat treatment time is 1-24h, and the pressure is 0.1-3MPa; the oxidation is performed by an oxidant.

7. A method for preparing the alumina support according to any one of claims 1 to 6, comprising: The raw materials including alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species and an optional inorganic compound other than alumina are granulated and surface-treated to obtain the alumina support; Wherein, the surface treatment method is selected from at least one of heat treatment, crystallization, oxidation, alkalization, and irradiation treatment; The heat treatment conditions include: the heat treatment atmosphere includes a first atmosphere and a second atmosphere, the first atmosphere is selected from at least one of carbon dioxide, water vapor, acetylene, ethylene, and methane, and the second atmosphere is selected from at least one of air, nitrogen, argon, and helium, the volume ratio of the first atmosphere to the second atmosphere is (0.05-1):1, the heat treatment temperature is 300-1200°C, the heat treatment time is 1-24h, and the pressure is 0.1-3MPa; the oxidation is performed by an oxidant.

8. The preparation method according to claim 7, characterized in that The preparation method comprises the following steps: (1) mixing alumina powder, a forming agent, a pore-forming agent, an inorganic carbon species, and optionally an inorganic compound other than alumina to obtain a mixed dry material; (2) Kneading the mixed dry materials into a shape and extruding them into granules; (3) Drying the product of step (2) and then performing the surface treatment to obtain the alumina carrier.

9. The preparation method according to claim 7, characterized in that: The alumina powder includes pseudo-boehmite powder and optionally other alumina powders except boehmite powder; and / or, The forming agent is at least one selected from polyethylene glycol cellulose, methyl cellulose, carboxymethyl cellulose, sodium hydroxymethyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose, and starch; and / or, The pore-forming agent is selected from at least one of polyvinyl alcohol, polyethylene glycol, polyacrylamide, polypropylene glycol, and sesbania powder; and / or, The inorganic compound is selected from at least one of silicon oxide, magnesium oxide, barium oxide, calcium oxide and hydrotalcite.

10. The preparation method according to claim 7, characterized in that: The amount of the inorganic carbon species is 1-40 parts by mass relative to 100 parts by mass of the alumina powder; and / or In parts by mass, the amount of the forming agent is 1-15 parts relative to 100 parts of alumina powder; and / or, In parts by mass, the amount of the pore former is 1-15 parts relative to 100 parts of alumina powder, and / or, In parts by mass, the amount of the inorganic compound is 0-30 parts relative to 100 parts of the alumina powder.

11. The preparation method according to claim 7, characterized in that: In parts by mass, the amount of the inorganic compound is 0-28 parts relative to 100 parts of alumina powder.

12. The preparation method according to claim 7, characterized in that: The crystallization conditions include: 120-250° C., 4-18 h, 0.2-15 MPa, and / or, the solvent is selected from at least one of water, ethanol, ethylene glycol, and ethylenediamine; and / or, The oxidation conditions include: 30-80° C., 0.2-10 h, an oxidant selected from at least one of nitric acid, sulfuric acid, ammonium persulfate, hydrogen peroxide, potassium permanganate, and ascorbic acid, and an oxidant concentration of 0.1 mol / L-10 mol / L; and / or, The alkalization conditions include: 30-110° C., 0.2-10 h, the alkaline compound is selected from at least one of sodium hydroxide, sodium bicarbonate, sodium carbonate, sodium acetate, sodium oxalate, sodium citrate, potassium hydroxide, potassium bicarbonate, potassium carbonate, potassium acetate, and potassium citrate, and the concentration of the alkaline compound is 0.1 mol / L-10 mol / L; and / or, The irradiation ray source is selected from gamma rays and / or microwaves.

13. The preparation method according to claim 7, characterized in that: The irradiation radiation source is selected from gamma rays and / or microwaves; the gamma ray irradiation dose rate is 2-90 kGy / min, and the time is 0.2-24 h; and / or the microwave power is 50-1000 W, and the time is 0.5-60 min.

14. The preparation method according to any one of claims 7 to 13, characterized in that: The surface treatment method is selected from: heat treatment; or crystallization and oxidation; or heat treatment and irradiation treatment; or heat treatment and alkalization; or heat treatment, alkalization and irradiation.

15. The preparation method according to any one of claims 7 to 13, characterized in that: When the inorganic carbon species is coke, activated carbon, carbon black, white carbon, or glassy carbon, heat treatment is used; or surface treatment is performed by crystallization and oxidation; When the inorganic carbon species is charcoal, bamboo charcoal, or coconut shell charcoal, heat treatment is used; or, surface treatment is performed by heat treatment and irradiation; When the inorganic carbon species is graphene, graphyne, or diamond, the surface treatment is performed by crystallization and oxidation; or heat treatment and alkalization; or heat treatment, alkalization, and irradiation.

16. Use of the alumina carrier according to any one of claims 1 to 6, or the alumina carrier prepared by the preparation method according to any one of claims 7 to 15, in a catalyst.

17. The use according to claim 16, characterized in that: The catalyst contains a metal element.

Images