阅读说明：本技术 一种脱除油品中溶解氧的方法 (Method for removing dissolved oxygen in oil product ) 是由 王玉 刘冬 蔡吉乡 许正跃 凌正国 周立群 顾文忠 曹晶 耿祖豹 施祖伟 邱祥涛 于 2019-12-03 设计创作，主要内容包括：本发明涉及一种脱除油品中溶解氧的方法,其特征在于油品在进入反应器前先使其与氢气通过混合器充分混合,之后再进入反应器与除氧催化剂接触,所述催化剂包括一载体和负载在所述载体上的至少一种催化组分,所述载体包括至少一第一层载体和一第二层载体,所述第二层载体从空间上包覆所述第一层载体,所述第二层载体沉积了至少一种所述催化组分。本发明除氧稳定性好,效率高寿命长,对油品中微量溶解氧脱除率可达到95％以上。(The invention relates to a method for removing dissolved oxygen in oil, which is characterized in that the oil is fully mixed with hydrogen through a mixer before entering a reactor, and then enters the reactor to contact with an oxygen removal catalyst, wherein the catalyst comprises a carrier and at least one catalytic component loaded on the carrier, the carrier comprises at least one first layer of carrier and a second layer of carrier, the second layer of carrier spatially coats the first layer of carrier, and the second layer of carrier deposits at least one catalytic component. The invention has good deoxidization stability, high efficiency and long service life, and the removal rate of trace dissolved oxygen in oil products can reach more than 95 percent.)

1. A method for removing dissolved oxygen in oil is characterized in that the oil is fully mixed with hydrogen before entering a reactor, and then enters the reactor to contact with an oxygen removal catalyst, wherein the catalyst comprises a carrier and at least one catalytic component loaded on the carrier, the carrier comprises at least one first layer of carrier and a second layer of carrier, the second layer of carrier spatially coats the first layer of carrier, and the second layer of carrier is deposited with at least one catalytic component.

2. The method of claim 1, wherein the ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier is between 0.01 and 0.2.

3. The method according to claim 1, wherein the second layer of carrier has a distribution of first type pores and second type pores, the first type pores having a maximum pore size distribution between 4 and 50nm, and the second type pores having a maximum pore size distribution between 100 and 1000 nm.

4. The method according to claim 3, wherein the first type of pores has a pore size distribution ranging from 10 to 20nm and the second type of pores has a pore size distribution ranging from 150 to 500 nm.

5. A method according to claim 1, characterized in that the method comprises the step of depositing the at least one IUPAC group 8-14 metal to the second layer carrier.

6. The method of claim 1, wherein intimately mixing the oil with hydrogen prior to entering the reactor further comprises: the oil and the hydrogen are mixed by the mixer, the mixer is composed of a shell and a cylindrical filter, the cylindrical filter is not in contact with the inner wall of the shell, and an annular channel is formed between the cylindrical filter and the shell.

7. The method according to claim 6, wherein the pore size of the cylindrical filter is 1 to 10 μm.

8. The method of claim 1, wherein the volume ratio of the hydrogen gas to the oil mixture is 1.0 to 4.0.

9. The method according to claim 1, characterized in that the hydrodeoxygenation reaction conditions are: temperature: hydrogen oil body at 40-80 deg.CProduct ratio: 1.0-4.0, pressure: 0.2-1.0 MPa, airspeed: 10 to 20 hours^-1。

10. The catalyst of claim 1, wherein the first layer carrier has a pore volume of 0.3ml/g or less and a BET specific surface area of 20m or less²/g。

Technical Field

The invention relates to a method for removing oxygen, in particular to a method for removing dissolved oxygen in oil products.

Background

Many industrial processes include oxygen removal processes such as treatment of boiler water, oil field water, and refining of high purity gases, propylene, syngas, and the like. The method for removing oxygen mainly comprises two main categories of physical oxygen removal and chemical oxygen removal, wherein the physical method comprises the following steps: vacuum deoxygenation, atmospheric thermal deoxygenation, rectification, adsorption, membrane separation, desorption, oxygen removal and the like, and chemical deoxygenation is further divided into chemical absorption (adsorption) deoxygenation, deoxygenation by utilizing the reaction of oxygen and deoxidants such as activated carbon and the like to generate carbon dioxide, deoxygenation by utilizing a valence-variable oxide reducing agent, deoxygenation by catalytic hydrogenation, oxygen removal by utilizing hydrogen removal and the like.

In the petrochemical industry, straight-run oil products such as kerosene often dissolve trace oxygen in the storage and transportation process, and the dissolved oxygen reacts with unstable hydrocarbons in the kerosene at high temperature to generate oxidized colloid, which easily causes the blockage of equipment. For example, CN102876375B discloses a pretreatment method of catalytically cracked gasoline, which comprises introducing oxygen-containing FCC gasoline into a stripping tower, and stripping with hydrogen; the obtained gas enters a gas purification and deoxidation reactor and contacts with a catalyst I to purify the gas and remove oxygen; and mixing the obtained liquid with purified hydrogen, then feeding the mixture into a reactor, and contacting the mixture with a catalyst II to remove dialkene and residual oxygen in the gasoline. The oxygen-containing FCC gasoline firstly enters a stripping tower for stripping, and the dissolved oxygen in the gasoline is removed; the deoxidized FCC gasoline hydrogenates the alkadiene at a lower temperature, thereby removing the oxygen and the alkadiene dissolved in the gasoline step by step, and effectively avoiding the alkadiene and the oxygen from being recombined in the hydrogenation process. The gasoline in this patent is still relatively inefficient in oxygen removal.

Disclosure of Invention

The invention aims to provide a catalytic hydrogenation method for removing dissolved oxygen in an oil product by using a high-efficiency catalyst, so as to obviously improve the coking phenomenon of the oil product in the high-temperature production process and improve the oxygen removal efficiency.

In an embodiment of the present application, a method for removing dissolved oxygen from an oil product is provided, wherein the oil product is sufficiently mixed with hydrogen before entering a reactor, and then enters the reactor to contact with an oxygen removal catalyst, the catalyst comprises a carrier and at least one catalytic component loaded on the carrier, the carrier comprises at least a first layer of carrier and a second layer of carrier, the second layer of carrier spatially coats the first layer of carrier, the material of the first layer of carrier is different from the material of the second layer of carrier, and the second layer of carrier has at least one catalytic component deposited thereon.

Optionally, the ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier is between 0.01 and 0.2.

Optionally, the second layer of carrier has a first type of pores and a second type of pores distributed therein, the maximum value of the pore size distribution of the first type of pores is between 4 nm and 50nm, and the maximum value of the pore size distribution of the second type of pores is between 100 nm and 1000 nm.

Optionally, the pore size distribution range of the first type of pores is between 10 and 20nm, and the pore size distribution range of the second type of pores is between 150 and 500 nm.

The method comprises the step of depositing the at least one IUPAC group 8-14 metal onto the second layer of support.

Optionally, the fully mixing the oil with hydrogen before entering the reactor further comprises: the oil and the hydrogen are mixed by the mixer, the mixer is composed of a shell and a cylindrical filter, the cylindrical filter is not in contact with the inner wall of the shell, and an annular channel is formed between the cylindrical filter and the shell. The pore diameter of the cylindrical filter is 1-10 microns.

Optionally, the volume ratio of the hydrogen to the oil mixture is 1.0-4.0.

Alternatively, the hydrodeoxygenation reaction conditions are: temperature: at 40-80 ℃, volume ratio of hydrogen to oil: 1.0-4.0, pressure: 0.2-1.0 MPa, airspeed: 10 to 20 hours^-1。

Optionally, the pore volume of the first layer of the carrier is less than or equal to 0.3ml/g, and the BET specific surface area is less than or equal to 20m²/g。

The invention forms the catalyst carrier which is internally and externally opposite and comprises a first layer carrier and a second layer carrier by selecting different substances, catalytic reaction active centers are only distributed on the second layer carrier positioned on the outer layer, the diffusion distance of reactants and products in the catalyst is greatly shortened, two different types of holes are provided by adjusting the pore structure of the second layer carrier of the catalyst, the first type of holes provide high specific surface area and active centers required by the reaction, and the reaction activity of the catalyst is improved; the second type hole is used as a diffusion channel of the reactant and the product, so that the diffusion process of the reactant and the product is greatly improved, the deoxygenation reaction is more thorough, and the deoxygenation efficiency is greatly improved. Particularly for oil products with longer carbon chains (the number of carbon atoms is more than or equal to 10) such as kerosene and the like, the existence of the second type of pore canal with large pore diameter enables reactants and products to be rapidly diffused, the retention time in the catalyst is short, the pore canal of the catalyst is not easy to be blocked, the carbon deposition condition is improved, and the service life of the catalyst is obviously prolonged.

The catalyst still has higher activity at lower temperature and pressure, can keep higher reaction activity for a long time, can effectively remove trace oxygen dissolved in oil products, and has a trace oxygen removal rate of over 95 percent to the oil products, thereby obviously improving the coking and blocking phenomena of the oil products in the subsequent production process and achieving the aim of clean production. The method is simple and convenient to operate, and is particularly suitable for removing the trace oxygen dissolved in the straight-run kerosene oil products.

Detailed Description

The catalyst comprises a first layer carrier with low porosity and a second layer carrier with a porous structure coated on the first layer carrier, wherein various catalytic components are loaded on the second layer carrier with the porous structure.

The carrier of the catalyst provided by the invention is provided with a first type of holes and a second type of holes, wherein the maximum value of the pore size distribution of the first type of holes is between 4 and 50nm, and the maximum value of the pore size distribution of the second type of holes is between 100 and 1000 nm.

The catalyst carrier is formed by combining a first layer carrier and a second layer carrier which are respectively formed by two substances with different properties inside and outside. The material of the first layer carrier may include, but is not limited to, a-alumina, silicon carbide, mullite, cordierite, zirconia, titania, a mixture of one or more of the metals. The first layer of carrier material can be shaped into different shapes, such as spheres, strips, sheets, rings, gears, cylinders, etc., as desired. A preferably spherical first layer carrier, which may have a diameter of 0.5mm to 10mm, preferably 1.2mm to 2.5 mm. When the first layer carrier is spherical, the diameter refers to the actual diameter of the first layer carrier; when the first layer carrier is non-spherical, the diameter refers to the "effective diameter", i.e., the diameter of the first layer carrier when it is formed into a spherical shape. The carrier forming method of the first layer can be selected from carrier forming methods known in the field according to the characteristics of materials, such as compression molding, extrusion molding, rolling ball forming, dropping ball forming, granulation molding, melt molding and the like. According to the difference of the carrier material forming the first layer, the raw material powder is added with one or more of inorganic acids or organic acids such as nitric acid, hydrochloric acid, citric acid, glacial acetic acid and the like which are 2-20% of the weight of the powder and a small amount of water, and the mixture is fully mixedMixing and forming, placing the formed first layer carrier in a closed space at 40-90 ℃ under the conditions of constant temperature and constant humidity, continuously reacting for 5-24 hours, keeping the humidity environment at a proper temperature to promote the crystal structure to be fully converted, and drying at 100-150 ℃ for 2-8 hours. The dried first layer of carrier needs to be fired and shaped at a certain temperature to finally form a structure with low porosity, the firing temperature is at least higher than the using temperature of the catalyst and is generally 450-1700 ℃ according to the characteristics of different materials. The first layer of the carrier is a low-porosity substance, specifically, the pore volume is less than or equal to 0.3ml/g, the BET specific surface area is less than or equal to 20m²Material/g. In one embodiment of the present application, the material comprising the first layer of support is a low porosity substance, which prevents infiltration of the catalytic component. In the catalyst containing a noble metal such as platinum or palladium, in order to reduce the cost, the noble metal supported on the waste catalyst is recovered and used after the catalyst is deactivated and replaced, and the recovery process requires that the waste catalyst is completely dissolved by an acid or an alkali to precipitate the supported noble metal into a solution and then recover the noble metal. The substance constituting the second layer carrier can be dissolved completely by an acid or a base in general, and the noble metal component supported in the second layer carrier can be recovered relatively easily. However, the material constituting the first layer carrier is often not completely dissolved by the acid and alkali, and if the noble metal permeates into the first layer carrier to a large extent, it is difficult to completely recover the noble metal by the chemical process, and the recovered first layer carrier still contains a large amount of noble metal, resulting in a low noble metal recovery rate, so that it is advantageous to reduce the amount of the noble metal contained in the first layer carrier as much as possible. The first layer carrier with low porosity prevents the infiltration of catalytic components, has extremely low content of noble metals, improves the utilization efficiency of the catalytic components, and reduces the difficulty of recovering the noble metals from the waste catalyst. Meanwhile, the lower porosity of the first layer of carrier prevents inward diffusion of reactants and products, shortens the diffusion distance of the reactants and the products in the catalyst and reduces the occurrence of side reactions.

The second support material may be selected from, but is not limited to, gamma alumina, delta alumina, eta alumina, theta alumina, zeolites, non-zeolitic molecular sieves, titania, zirconiaAnd cerium oxide. Gamma-alumina, delta-alumina, zeolites, non-zeolitic molecular sieves are preferred. The material forming the second layer carrier is a porous substance and has two different types of pore channel structures, the maximum value of the pore size distribution of the first type of pores is between 4 and 50nm, and the maximum value of the pore size distribution of the second type of pores is between 100 and 1000 nm. The total volume of the two types of pores is at least 0.5ml/g, preferably at least 1.0 ml/g. The two types of pores each provide a ratio of pore volume between 1:9 and 9:1, preferably between 3:7 and 7: 3. The BET specific surface area of the second layer of support material is at least 50m²A/g, preferably of at least 100m²/g。

The combination of the second layer carrier and the first layer carrier can be achieved by first forming a slurry of the second layer carrier material and then using the prior art methods of dipping, spraying, coating, etc., but is not limited to the above methods. The preparation of the second layer carrier material slurry usually includes a peptization process, in which the second layer carrier material with a porous structure is mixed with water according to a certain proportion and stirred, and usually a certain amount of peptizing agent, such as nitric acid, hydrochloric acid or organic acid, is added, and the amount of peptizing agent is 0.01% -5% of the total amount of the slurry. The thickness of the second layer support can be controlled by the amount of second layer support material slurry used. The invention finds that the thickness of the second layer carrier is not a certain value, and changes along with the diameter of the first layer carrier, so as to obtain the optimal catalyst reaction performance, and particularly, the ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier is between 0.01 and 0.2.

The second layer support material having two types of pores may be made of a single porous substance (as in example 1), for example, by applying a slurry of the second layer support material having two types of pores (the maximum values of the pore size distribution are 10 to 20nm and 150 to 300nm, respectively) to the first layer support; or, according to the pore structure of the selected second layer carrier material itself, a certain amount of pore-forming agent may be selectively added, so that the final catalyst has two different types of pore structures (as in example 2), for example, the pore-forming agent is added to the slurry of the second layer carrier material having one type of pores (the maximum value of the pore size distribution is 15 to 30nm), and the slurry of the second layer carrier material to which the pore-forming agent is added is coated on the first layer carrier. The pore-forming agent is selected from sesbania powder, methyl cellulose, polyvinyl alcohol, carbon black and other materials according to the required pore diameter, but is not limited to the materials, and the adding amount is controlled to be 5-50% of the mass of the second layer of the carrier material. The pore structure of the finally prepared catalyst is characterized in that the maximum value of the pore size distribution of the first type of pores is between 4 and 50nm, the maximum value of the pore size distribution of the second type of pores is between 100 and 1000nm, the pore volume provided by the first type of pores accounts for 10 to 90 percent, preferably 30 to 70 percent, of the total pore volume, and the pore volume provided by the second type of pores accounts for 90 to 10 percent, preferably 70 to 30 percent, of the total pore volume.

The combination of the second layer of carrier and the first layer of carrier can be completed only by high-temperature roasting. Specifically, the first layer of carrier coated with the second layer of carrier material slurry is dried at 60-200 ℃ for 0.5-10 hours, and then is baked at 300-900 ℃ for a sufficient time, for example, 2-15 hours, so as to obtain the carrier.

The catalytic component of the catalyst comprises at least one IUPAC (IUPAC) group 8-14 metal, and is loaded on the carrier by adopting an impregnation method. Preferably, palladium is used as a main catalytic element, and one of silver, tin and lead is used as a promoter element. The content of palladium is 0.01-2% of the weight of the carrier, and the content of the cocatalyst element is 0.01-2% of the weight of the carrier. Drying the impregnated sample at 100-200 ℃ for 2-8 hours, roasting at 300-600 ℃ for 2-8 hours, continuously treating with water vapor for 0.5-4 hours, and reducing the roasted sample with hydrogen at room temperature to 300 ℃, preferably 60-150 ℃, for 0.5-10 hours, preferably 1-5 hours to obtain the catalyst.

The catalytic hydrogenation method for removing dissolved oxygen in oil by using the catalyst is characterized in that the oil is fully mixed with hydrogen before entering a hydrogenation reactor, and the mixed oil enters the reactor and contacts with the oxygen removal catalyst.

The oil and the hydrogen are mixed by the mixer, the mixer is composed of a shell and a cylindrical filter, the cylindrical filter is not in contact with the inner wall of the shell, and an annular channel is formed between the cylindrical filter and the shell.

The cylinder filter adopts a common sintered stainless steel filter cylinder, the pore diameter of the common sintered stainless steel filter cylinder is 1-10 microns, hydrogen and an oil product can be fully mixed, and the volume ratio of the hydrogen to the oil product is 1.0-4.0.

The hydrogenation reactor is a common fixed bed reactor, and the catalyst is filled in the hydrogenation reactor to form a catalyst bed layer.

When the catalyst is used for deoxidizing oil products, the suitable hydrogenation reaction conditions are as follows:

temperature: hydrogen-oil volume ratio at 40-80 ℃: 1.0 to 4.0

Pressure: airspeed of 0.2-1.0 MPa: 10 to 20 hours^-1

Example 1 preparation of catalyst A

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 10-20 nm and 150-300 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

500 g of high-purity Al is taken₂O₃Powder, 196 g of high-purity SiO₂Mixing the powder, 70 g of water and 10 g of 10% nitric acid, kneading for 1 hour, pressing into pellets, placing in a closed space at 70 ℃ under the conditions of constant temperature and constant humidity, continuing to react for 10 hours, drying at 150 ℃ for 2 hours, and roasting at 1450 ℃ for 1 hour to obtain a first layer of carrier pellets with the diameter of 2.0 mm. XRD analysis showed mullite crystal form.

50 g of alumina powder (with two types of holes, the pore diameter distribution ranges of the two types of holes are respectively 10-20 nm and 150-300 nm), 20 g of 20% nitric acid and 600 g of water are mixed and stirred for 2 hours to prepare alumina slurry. The slurry was sprayed with a spray gun onto a first layer of carrier pellets 2.0mm in diameter. Drying the pellets coated with the slurry at 100 ℃ for 6 hours, and then roasting at 500 ℃ for 6 hours to obtain a carrier containing an inner layer and an outer layer. Analysis showed the second layer support to have a thickness of 150 μm and a ratio to the first layer support diameter of 0.075.

The obtained carrier was impregnated with a 0.4mol/l palladium chloride solution, dried at 120 ℃ for 5 hours, calcined at 550 ℃ for 4 hours, and treated with water vapor for 1 hour. Reducing the mixture by hydrogen with the purity of more than 99 percent for 4 hours at 120 ℃ to prepare the catalyst A. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The catalyst is characterized by adopting a mercury intrusion method (ISO 15901-1 Evaluation of pore size distribution and location of solid materials by means of mercury condensation and gas adsorption), a curve (namely a pore volume-pore size curve) with the abscissa as pore size and the ordinate as pore volume is generated, two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores (namely the pore size value corresponding to the first peak in the curve, the same below) is 13nm, the maximum value of the pore size distribution of the second type of pores (namely the pore size value corresponding to the second peak in the curve, the same below) is 165nm, and the first type of pores have the volume of 0.7ml/g, the second type of pores have the volume of 0.88ml/g and the total pore volume of 1.58ml/g only by taking the mass of the second layer of the carrier as a base number.

Example 2 preparation of catalyst B

In the embodiment, alumina powder with one type of pores (the pore size distribution range is 15-30 nm) is added with a pore-forming agent methyl cellulose to prepare a second-layer carrier with two types of pores, mullite is used as a first-layer carrier, carriers containing an inner layer and an outer layer are obtained by effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

50 g of alumina powder (with a type of hole and the pore diameter distribution range of 15-30 nm), 20 g of 20% nitric acid, 12 g of methylcellulose and 600 g of water are mixed and stirred to prepare alumina slurry. The mixture was shaped according to the method of example 1 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed that the second layer support had a thickness of 110 μm and a ratio to the first layer support diameter of 0.055.

Catalyst B was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 19nm, the maximum value of the pore size distribution of the second type of pores is 252nm, and the volume of the first type of pores is 0.9ml/g, the volume of the second type of pores is 0.6ml/g and the total pore volume is 1.50ml/g only by taking the mass of the second layer of the carrier as a base number.

Example 3 preparation of catalyst C

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 8-18 nm and 200-500 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

50 g of alumina powder (with two types of holes, the pore diameter distribution ranges of the two types of holes are respectively 8-18 nm and 200-500 nm), 20 g of 20% nitric acid and 600 g of water are mixed and stirred for 2 hours to prepare alumina slurry. The mixture was shaped according to the method of example 1 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed a second layer carrier thickness of 240 μm, with a ratio of 0.12 to the first layer carrier diameter.

Catalyst C was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 11nm, the maximum value of the pore size distribution of the second type of pores is 383nm, and the volume of the first type of pores is 0.68ml/g, the volume of the second type of pores is 0.97ml/g and the total pore volume is 1.65ml/g only by taking the mass of the second layer of the carrier as a base number.

Example 4 preparation of catalyst D

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 8-15 nm and 50-200 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

50 g of alumina powder (with two types of holes, the pore diameter distribution ranges of the two types of holes are respectively 8-15 nm and 50-200 nm), 20 g of 20% nitric acid and 600 g of water are mixed and stirred for 2 hours to prepare alumina slurry. The mixture was shaped according to the method of example 1 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed a second layer of support having a thickness of 70 μm and a ratio to the first layer of support diameter of 0.035.

Catalyst D was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 9nm, the maximum value of the pore size distribution of the second type of pores is 120nm, and the volume of the first type of pores is 0.58ml/g, the volume of the second type of pores is 0.82ml/g and the total pore volume is 1.40ml/g only by taking the mass of the second layer of the carrier as a base number.

EXAMPLE 5 preparation of catalyst E

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 8-18 nm and 200-500 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

The mixture was shaped according to the procedure of example 3 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed a second layer support thickness of 200 μm, with a ratio of 0.1 to the first layer support diameter.

The prepared carrier is firstly soaked in 0.4mol/l palladium chloride solution, dried for 5 hours at 120 ℃ and roasted for 3 hours at 550 ℃. The roasted carrier is dechlorinated, then is soaked by 0.3mol/l stannic chloride solution, is dried for 5 hours at the temperature of 120 ℃, is roasted for 4 hours at the temperature of 550 ℃, and is treated for 1 hour by introducing water vapor. Reducing the mixture by hydrogen with the purity of more than 99 percent for 4 hours at 120 ℃ to prepare a catalyst E. Elemental analysis shows that the mass contents of the metal components are 0.2 percent of palladium and 0.4 percent of tin respectively based on the whole catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 11nm, the maximum value of the pore size distribution of the second type of pores is 410nm, and the volume of the first type of pores is 0.65ml/g, the volume of the second type of pores is 0.98ml/g and the total pore volume is 1.63ml/g only by taking the mass of the second layer of the carrier as a base number.

Comparative example 1 preparation of catalyst F

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 10-20 nm and 150-300 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

500 g of high-purity Al is taken₂O₃Powder, 196 g of high-purity SiO₂The powder, 70 g of water and 10 g of 10% nitric acid were mixed, kneaded for 1 hour, pressed into pellets, dried at 150 ℃ for 2 hours, and then calcined at 1450 ℃ for 1 hour to obtain first layer carrier pellets with a diameter of 2.0 mm. XRD analysis showed mullite crystal form.

The mixture was shaped according to the method of example 1 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed the second layer support to have a thickness of 150 μm and a ratio to the first layer support diameter of 0.075.

Catalyst F was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 13nm, the maximum value of the pore size distribution of the second type of pores is 165nm, and the volume of the first type of pores is 0.7ml/g, the volume of the second type of pores is 0.88ml/g and the total pore volume is 1.58ml/g only by taking the mass of the second layer of the carrier as a base number.

Comparative example 2 preparation of catalyst G

In the embodiment, alumina powder with one type of pores (the pore size distribution range is 8-15 nm) is used for preparing a second-layer carrier, mullite is used as a first-layer carrier, the carrier containing an inner layer and an outer layer is obtained through effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

The mixture was shaped according to the method of example 1 to obtain a carrier having two layers, an inner layer and an outer layer. Analysis showed that the thickness of the second layer support was 100 μm, which is a ratio of 0.05 to the diameter of the first layer support.

Catalyst G was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

Using the mercury intrusion method for characterization, it was found that there was one type of pores in the second layer of the catalyst support, the maximum value of the pore size distribution was 10nm, and the pore volume was 1.05ml/g based on the mass of the second layer support alone.

Comparative example 3 preparation of catalyst H

This example prepares a radially uniform composition alumina spherical support with two types of pores and prepares a catalyst.

50 g of alumina powder, 20 g of 20% nitric acid and 200 g of water are mixed and stirred to prepare alumina slurry. And preparing the slurry into pellets by an oil column molding method, drying the pellets for 6 hours at 100 ℃, and roasting the pellets for 6 hours at 500 ℃ to obtain the radial uniform carrier.

Catalyst H was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

By adopting the mercury intrusion method for characterization, two types of pores exist in the catalyst, the maximum value of the pore size distribution of the first type of pores is 11nm, the pore volume of the first type of pores is 0.66ml/g, the maximum value of the pore size distribution of the second type of pores is 380nm, the pore volume of the second type of pores is 0.94ml/g, and the total pore volume is 1.6 ml/g.

Comparative example 4 preparation of catalyst I

In the embodiment, one alumina powder with two types of pores (the pore diameter distribution ranges of the two types of pores are respectively 10-20 nm and 150-300 nm) is used for preparing the second layer of carrier, mullite is used as the first layer of carrier, the carrier containing an inner layer and an outer layer is obtained by effective combination, and the catalyst is prepared.

The first layer carrier was prepared according to the method of example 1.

50 g of alumina powder (with two types of holes, the pore diameter distribution ranges of the two types of holes are respectively 10-20 nm and 150-300 nm), 20 g of 20% nitric acid and 600 g of water are mixed and stirred for 2 hours to prepare alumina slurry. The slurry was sprayed with a spray gun onto a first layer of carrier pellets 1.3mm in diameter. Drying the pellets coated with the slurry at 100 ℃ for 6 hours, and then roasting at 500 ℃ for 6 hours to obtain a carrier containing an inner layer and an outer layer. Analysis showed a second layer carrier thickness of 350 μm, with a ratio of 0.27 to the first layer carrier diameter.

Catalyst I was obtained according to the catalyst preparation method of example 1. Elemental analysis showed that the palladium content by mass was 0.2% based on the entire catalyst.

The mercury intrusion method is adopted for characterization, and the two types of pores exist in the second layer of the catalyst carrier, the maximum value of the pore size distribution of the first type of pores is 13nm, the maximum value of the pore size distribution of the second type of pores is 165nm, and the volume of the first type of pores is 0.72ml/g, the volume of the second type of pores is 0.89ml/g and the total pore volume is 1.61ml/g based on the mass of the second layer of the catalyst carrier.

EXAMPLE 6 Pd content analysis of the first layer Carrier of the catalyst

The first layer support prepared according to example 1 was characterized by the mercury intrusion method described above and showed a pore volume of 0.11ml/g and a specific surface of 10m²/g。

The catalyst a obtained in example 1 was digested with 15% HCl to dissolve the second layer carrier, and the Pd content of the remaining first layer carrier was analyzed by X-ray fluorescence spectroscopy (GB/T6609.30-2009), which revealed that the Pd content in the first layer carrier was 0.0008 wt%.

Comparative example 5 catalyst first layer carrier Pd content analysis

The first layer support prepared according to comparative example 1 was characterized by the mercury intrusion method described above, and the result showed that the first layer support had a pore volume of 0.42ml/g and a specific surface of 50m²/g。

The catalyst F obtained in comparative example 1 was digested with 15% HCl to dissolve the second layer carrier, and the Pd content of the remaining first layer carrier was analyzed by X-ray fluorescence spectroscopy (GB/T6609.30-2009), which revealed that the Pd content in the first layer carrier was 0.016 wt%.

The first layer carrier is designed into a low-porosity substance, so that precious metals (such as platinum group metals) can be prevented from entering the first layer carrier, the recovery rate of the precious metals is improved, and the production cost is reduced.

As can be seen by comparing the data of comparative example 5 with that of example 6, the first layer carrier prepared by the method of example 1 has a pore volume of 0.11ml/g and a specific surface of 10m²Per g, very low porosity, whereas the first layer of support prepared by the method of comparative example 1 has a pore volume of 0.42ml/g and a specific surface of 50m²The porosity is higher. Meanwhile, as can be seen from the comparative data, after acid digestion, the content of the residual Pd in the catalyst a with low porosity of the first layer carrier is much less than 0.0008 wt% of the residual Pd in the catalyst F with high porosity of the first layer carrier, which is much less than 0.016 wt%. The first layer carrier of the catalyst A is a substance with extremely low porosity, so that Pd is prevented from entering the first layer carrier, the catalyst A has higher Pd recovery rate, the noble metal use efficiency is higher, and the catalyst use cost is lower.

Example 7 comparison of oxygen scavenging Effect

Respectively loading the prepared catalysts into a reactor, controlling the reaction temperature at 70 ℃, the pressure at 0.8MPa and the LHSV at 10h^-1，H₂The volume/oil ratio was 1.0. After passing kerosene through the reactor, the change in oxygen content was analyzed, and the results are shown in Table 1 below.

TABLE 1 oxygen scavenging test results

The data in table 1 show that the oxygen removal rate of the five catalysts A, B, C, D, E with two-layer carriers and two types of pore channel distributions prepared in examples 1 to 5 of the present invention is significantly improved compared to the comparative catalyst G, H. The oxygen removal rate of catalyst a with the low porosity first layer carrier is higher than that of catalyst F with the higher porosity first layer carrier. The oxygen removal rate of the catalyst A, B, C, D, E with the ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier being 0.01-0.2 is higher than that of the catalyst I with the ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier not being 0.01-0.2.

Example 8 catalyst service life

Loading the obtained catalyst E into a reactor, controlling the reaction temperature at 55 deg.C, the pressure at 0.8MPa, and the LHSV at 20h^-1，H₂The volume ratio/oil was 3.0. The service life of the catalyst was examined and the results are shown in the following table.

TABLE 2 catalyst Life (service time) test results

As can be seen from the data in Table 2, the catalyst still had a high oxygen removal rate after 4000 hours of continuous operation.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.