Palladium type carbon monoxide combustion improver and preparation method thereof

Abstract

The invention discloses a palladium-type carbon monoxide combustion improver which comprises a modified carrier and an active component, the modified carrier is prepared by mixing and modifying gamma-aluminum oxide and modified silicon dioxide, and the active component is palladium metal. The preparation method comprises the following steps: S1, preparing a modified carrier: performing plasma treatment on gamma-aluminum oxide and modified silicon dioxide, adding an auxiliary agent, a surfactant and deionized water, performing ultrasonic treatment, drying and calcining; s2, preparation of a precursor solution: mixing and dissolving palladium metal soluble salt and a nitric acid solution; s3, preparation of a combustion improver finished product: performing ultrasonic treatment and spray drying on the modified carrier and the active palladium metal precursor solution, preserving heat at 450-500 DEG C, and reducing at 300-320 DEG C to obtain the combustion improver finished product. The palladium-type carbon monoxide combustion improver prepared by the invention is high in activity, can improve the conversion rate of carbon monoxide and reduce the content of nitrogen oxides, and is simple in preparation method and suitable for large-scale popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical combustion improvers, in particular to a palladium-type carbon monoxide combustion improver and a preparation method thereof. Background Art

[0002] During the production of light petroleum, the cracking of large molecular hydrocarbons will produce coke that adheres to the surface and pores of the catalytic cracking catalyst, reducing the activity of the catalyst. The coked catalyst comes into contact with oxygen-containing gas under high temperature conditions, and the deposited coke is converted into carbon monoxide (CO) and carbon dioxide (CO2) gases. These CO gases are discharged with the flue gas and pollute the environment. If they rise to the dilute phase bed at the top of the regenerator along with the catalyst, they will further burn and release a large amount of heat, causing the catalyst structure and performance in this section to be destroyed, and will also cause certain damage to the equipment, thereby affecting the progress of the catalytic cracking reaction of petroleum.

[0003] Flue gas produced during the FCC process contains CO and NO X (Nitrogen oxides) are harmful gases that pollute the environment and affect the production of light oil. To address this technical issue, researchers typically add a carbon monoxide combustion aid to the catalyst to increase the CO reaction rate, converting CO into CO2 in the dense phase of the regenerator, thereby recovering heat and reducing CO emissions, thereby reducing environmental pollution.

[0004] Carbon monoxide combustion improver is an additive in the catalytic cracking process in the petrochemical industry. It can convert CO in the regenerator flue gas into CO2 and reduce NO X The generation of oil can achieve the goals of saving energy, increasing light oil yield and reducing environmental pollution.

[0005] The addition of carbon monoxide combustion aids currently on the market reduces the CO content in the flue gas while increasing the NO content. The carriers used are usually ordinary alumina or silica, which have a small number of active sites and low activity. They are easily deactivated during high-temperature use and are difficult to meet production needs.

[0006] Therefore, improving the activity of carbon monoxide combustion aid, increasing CO conversion, and reducing NO X content is a technical problem that needs to be solved urgently in the petrochemical industry. Summary of the Invention

[0007] The purpose of the present invention is to provide a palladium type carbon monoxide combustion improver and a preparation method thereof, so as to solve the problems of low carbon monoxide combustion improver activity, low CO conversion rate, and NO X The problem of high content.

[0008] In a first aspect, the present invention provides a palladium-type carbon monoxide combustion aid, comprising a modified carrier and an active component; wherein the modified carrier is prepared by mixing γ-alumina and modified silica, treating the mixture in a plasma device, adding an auxiliary agent, a surfactant, and deionized water, ultrasonically treating the mixture, drying the mixture, and vacuum calcining the mixture; the active component is palladium metal; and the active component is supported on the modified carrier.

[0009] In a second aspect, the present invention provides a method for preparing a palladium-type carbon monoxide combustion improver, comprising the following preparation steps: S1. Preparation of modified carrier: γ-alumina and modified silica are mixed at a ratio of 20 to 25:1 and then placed in a plasma device for treatment for 4 to 5 minutes to obtain a pretreated carrier; 35 to 40 parts by weight of the pretreated carrier, 5 to 8 parts by weight of an auxiliary agent, 2 to 4 parts by weight of a surfactant, and 50 to 60 parts by weight of deionized water are weighed and placed in an ultrasonic device with a frequency of 85 to 90 Hz and a temperature of 45 to 50°C for treatment for 15 to 18 minutes, then filtered and dried in a drying oven at 50 to 60°C for 4 to 5 hours to obtain a pretreated modified carrier; the pretreated modified carrier is calcined under vacuum conditions at 450 to 500°C for 3 to 4 hours and then cooled to obtain a modified carrier.

[0010] S2. Preparation of precursor solution: Weigh 15-20 parts by weight of a soluble salt of palladium metal and 50-60 parts by weight of a nitric acid solution with a mass concentration of 60-65%, and stir at 55-60°C until the soluble salt of palladium metal is completely dissolved to obtain an active palladium metal precursor solution.

[0011] S3. Preparation of finished combustion aid: Weigh 60-70 parts by weight of a modified carrier and 28-32 parts by weight of an active palladium metal precursor solution, and place them in an ultrasonic device at a frequency of 90-100 Hz and a temperature of 45-50°C for treatment for 25-30 minutes to obtain a mixture; spray-dry the mixture in a spray drying device and place it in a muffle furnace. Under a nitrogen atmosphere, heat the mixture at a heating rate of 5°C / min to 450-500°C and maintain it for 2.0-2.5 hours to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor and reduce it at 300-320°C for 1.5-2.0 hours to obtain a finished combustion aid.

[0012] As a preferred technical solution of the present invention, the modified silicon dioxide is prepared by the following method: Step 1: Weigh 20-25 parts by weight of silica, 4-6 parts by weight of γ-aminopropyltriethoxysilane, 2-4 parts by weight of polyethylene glycol, 1-3 parts by weight of toluenesulfonic acid, 0.5-1.0 parts by weight of alkyl glycoside, and 55-60 parts by weight of deionized water in a reactor at 80-85° C. for 2.0-2.5 hours to obtain a pretreated silica mixture.

[0013] Step 2: Filter the pretreated silica mixture, wash it with deionized water and ethanol twice, centrifuge it, dry it in a vacuum drying oven at 60-70°C for 4-5 hours, and cool it to room temperature to obtain modified silica.

[0014] As a preferred technical solution of the present invention, the surfactant is composed of alkyl glycoside and 2,5-furan dimethanol in a mass ratio of 1:2 to 3.

[0015] As a preferred technical solution of the present invention, the charge density of the plasma equipment is 1100-1200 C / cm 3 , gas flow rate is 1.3~1.6L / min, pressure is 90~100kPa, and temperature is 50~60℃.

[0016] As a preferred technical solution of the present invention, the auxiliary agent is composed of cerium nitrate and zirconium nitrate in a mass ratio of 2:1.

[0017] As a preferred technical solution of the present invention, the soluble salt of palladium metal is any one of palladium chloride, palladium nitrate, palladium acetate, or a mixture of two substances.

[0018] As a preferred technical solution of the present invention, the spray drying pressure is 2.5-2.8 MPa, the feed rate is 10-11 kg / h, the inlet air temperature is 120-125°C, and the exhaust air temperature is 75-80°C.

[0019] As a preferred technical solution of the present invention, when the combustion-supporting agent semi-finished product reacts in the reactor, a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 is introduced at a flow rate of 30 mL / min.

[0020] As a preferred technical solution of the present invention, the Al2O3 content of the γ-alumina is greater than 98%, the Na2O content is less than 0.5%, and the Fe2O3 is less than 0.05%; the particle size of the γ-alumina is 5 to 20 μm, and the specific surface area is 260 to 320 m 2 / g).

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The palladium metal active carrier used in the present invention is a modified carrier made by mixing γ-alumina and modified silica. The γ-alumina has a particle size of 260 to 320 m 2The high specific surface area (0.175 μg / g), fine particle size of 5-20 μm, and abundant pore structure provide ample attachment sites for the active component palladium in the combustion aid, enabling its uniform dispersion. This increases the contact area between the active component palladium and carbon monoxide, improving the efficiency of the combustion-supporting reaction. Furthermore, the hydroxyl groups (-OH) on the surface of γ-alumina can form stable chemical bonds (such as palladium-oxygen-aluminum bonds) with the active component palladium, preventing the loss of the active component during the reaction. Furthermore, through electronic effects, they regulate the active component's redox properties, enhancing its catalytic oxidation of carbon monoxide and achieving a synergistic effect between the support and the active component. Furthermore, γ-alumina maintains structural stability under high temperature conditions, is not susceptible to phase changes, and effectively resists damage to the support structure caused by high temperatures, ensuring that the performance of the combustion aid will not rapidly degrade during long-term use. The addition of modified silica further enhances the thermal stability of the support, enabling the modified support to maintain good performance under high temperature conditions. γ-alumina, with its abundant mesoporous structure and high specific surface area, provides ample loading sites for the active component. The addition of modified silica can improve the mechanical strength and wear resistance of the carrier, reduce the wear and breakage of the combustion aid during the catalytic reaction, and extend the service life of the catalyst. Modified silica can also adjust the surface hydrophilicity or acidic sites, make up for the defect of strong alkalinity on the surface of γ-alumina, and enhance the chemical stability of the carrier. The mixture of γ-alumina and modified silica can optimize the pore structure of the carrier, such as pore size distribution and specific surface area, improve mass transfer efficiency, reduce the diffusion resistance of reactants, improve reaction activity and catalytic efficiency, thereby increasing CO conversion rate and reducing NO X content.

[0022] 2. The surface of modified silica is rich in silanol (Si-OH) and silicon-oxygen bonds (Si-O-Si). Active functional groups such as amino and carboxyl groups can be introduced through chemical modification to enhance the binding force with palladium particles and prevent palladium particles from agglomerating. Modified silica can form Pd-O-Si bonds with palladium, reduce the stability of the oxidation state of palladium, promote the reduction reaction, and thus enhance the catalytic activity of the combustion aid. γ-aminopropyltriethoxysilane is hydrolyzed to form silanol groups (Si-OH), which can react with the hydroxyl groups on the surface of silica to form covalent bonds and expose amino groups (-NH2); amino groups, as strong coordination groups, can efficiently anchor palladium ions (Pd 2+ ), forming a stable Pd-N coordination bond to prevent palladium from migrating or sintering during the reduction process and affecting its activity; and the surface of silica modified with γ-aminopropyltriethoxysilane is positively charged, which can evenly disperse palladium particles through electrostatic repulsion, narrowing the particle size distribution and exposing more palladium active sites, thereby improving the activity of the combustion aid, increasing the CO conversion rate and reducing NO XContent. The polyethylene glycol molecular chain can be wrapped on the surface of the palladium particles to form a physical barrier, inhibiting sintering caused by direct contact between particles; and the ethylene oxide chain (-O-CH2-CH2-) of polyethylene glycol can interact weakly with hydrogen, slowly releasing hydrogen atoms to achieve mild reduction of palladium ions, and avoid abnormal particle growth caused by local overheating; in addition, the hydrophobic chain segment of polyethylene glycol can adsorb poisons such as sulfide and chloride in the exhaust gas, reducing its contact with the active sites of palladium, which is beneficial to maintaining the activity of the combustion aid. The non-ionic properties of alkyl glycosides enable it to be adsorbed on the surface of silica and palladium particles at the same time, stabilizing the dispersed system through the dual effects of steric hindrance and electrostatic repulsion, while reducing the surface tension of the liquid, enhancing the wettability of the carrier and palladium precursor, preventing palladium particles from agglomerating, narrowing the particle size distribution, exposing more active sites, improving CO conversion rate, and reducing NO X content.

[0023] 3. The present invention incorporates surfactants, alkyl glycosides and 2,5-furan dimethanol, during the preparation of the modified support. The molecular structure of alkyl glycosides combines a hydrophilic head group (glucose unit) with a hydrophobic tail chain (alkyl group), which can reduce the surface tension of the prepared system, promote uniform dispersion of the active component palladium on the surface of the composite support, reduce active component agglomeration, and improve its utilization. Alkyl glycosides can act as "soft templates." The hydrophilic and hydrophobic ends of alkyl glycosides enable them to spontaneously form nanostructures, such as micelles and liquid crystal phases, in solution, providing a template framework for the synthesis of mesoporous materials. During the preparation of the modified support, alkyl glycosides guide pore formation through self-assembly, optimizing the pore size distribution of the γ-alumina / modified silica, enhancing the diffusion efficiency of gases (such as CO and O2) within the support, and providing ample mass transfer channels for the CO oxidation reaction, thereby improving the CO conversion rate. The hydroxyl groups of 2,5-furan dimethanol can form hydrogen bonds with the aluminum hydroxyl groups (Al-OH) on the surface of γ-alumina or the silicon hydroxyl groups (Si-OH) on the surface of modified silica; at the same time, the π electrons of the furan ring can form hydrogen bonds with the active palladium ions (Pt 2+) to produce a coordination effect, thereby enhancing the anchoring strength of the active components on the carrier surface, reducing the sintering or shedding of the active components at high temperatures, and extending the life of the combustion aid; at the same time, the introduction of 2,5-furan dimethanol can adjust the hydrophilicity and acidity and alkalinity of the carrier surface. The hydrophobicity of the furan ring can reduce the adsorption of water vapor by the carrier and avoid hydration inactivation, while the weak polarity of the hydroxyl group can enhance the adsorption capacity of CO molecules, promote the enrichment and activation of CO at the active sites, and improve the CO conversion rate; in addition, 2,5-furan dimethanol can participate in the cross-linking of the modified carrier through the hydroxyl condensation reaction during the calcination process, forming a denser network structure, and enhancing the mechanical strength of the modified carrier, such as wear resistance and impact resistance; furthermore, the furan ring structure of 2,5-furan dimethanol is resistant to high temperatures, which can reduce the structural damage of the carrier at high temperatures. Alkyl glycosides promote uniform dispersion of active ingredients through surface activity, while 2,5-furan dimethanol firmly anchors the dispersed active ingredients to the carrier surface through coordination and hydrogen bonding. The combination of these two significantly reduces agglomeration of active ingredients and increases the specific surface area of ​​the modified carrier. Alkyl glycosides act as soft templates to regulate the formation of abundant mesopores in the carrier, while the cross-linking effect of 2,5-furan dimethanol stabilizes the pore structure, resulting in a carrier with "high porosity and suitable pore size distribution," reducing the diffusion resistance of CO and O2 within the carrier and increasing the rate of the combustion-supporting reaction.

[0024] 4. During the preparation of the modified support, the present invention subjects γ-alumina and modified silica to plasma treatment. The high-energy particles in the plasma, through collision, can remove impurities such as oil and organic residues remaining on the support surface, decompose chemically adsorbed inert groups such as hydrocarbon chains, expose more active sites, enhance flame retardant activity, and improve CO conversion. Furthermore, the high-energy particles in the plasma can oxidize the support surface, increasing the density of oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH), thereby increasing the loading capacity of the active components. Furthermore, the high-energy impact of the plasma can break weak binding forces such as van der Waals forces between the particles, unblocking clogged mesopores and concentrating the pore size distribution. Furthermore, the high-energy particles in the plasma can activate aluminum hydroxyl (Al-OH) groups on the surface of γ-alumina and silicon hydroxyl (Si-OH) groups on the surface of modified silica, causing a dehydration condensation reaction between the two at the interface to form Al-O-Si bonds, thereby improving the overall mechanical strength of the modified support. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flow chart for preparing the palladium-type carbon monoxide combustion improver. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] like Figure 1 The method for preparing the palladium-type carbon monoxide combustion-supporting agent of the present invention is shown, comprising the following preparation steps: S1. Preparation of modified carrier: (i) Modified silica is prepared by the following method: silica, γ-aminopropyltriethoxysilane, polyethylene glycol, toluenesulfonic acid, alkyl glycoside, and deionized water are reacted in a reactor at 80-85°C for 2.5 hours to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, then washed with deionized water and ethanol twice in sequence, centrifuged, and then dried in a vacuum drying oven at 60°C, and cooled to room temperature to obtain modified silica. (ii) Preparation of modified carrier: γ-alumina and modified silica are mixed uniformly and then treated in a plasma device to obtain a pretreated carrier; the pretreated carrier, auxiliary agent, surfactant, and deionized water are placed in an ultrasonic device for treatment, filtered, and dried to obtain a pretreated modified carrier; the pretreated modified carrier is calcined under vacuum conditions and cooled to obtain a modified carrier. S2. Preparation of precursor solution: Stir and dissolve the soluble salt of palladium metal and nitric acid solution to obtain an active palladium metal precursor solution. S3. Preparation of finished combustion aid: Place the modified carrier and active palladium metal precursor solution in an ultrasonic device for treatment, spray dry, and place in a muffle furnace. In a nitrogen atmosphere, keep the temperature at 450-500°C to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor, introduce a mixture of hydrogen and nitrogen with a gas ratio of 1:8 at a flow rate of 30 mL / min, and reduce at 300-320°C to obtain a finished combustion aid.

[0028] The raw materials used in the present invention are all commercially available raw materials.

[0029] Example 1:

[0030] The preparation method of palladium-type carbon monoxide combustion improver comprises the following preparation steps: S1. Preparation of modified carrier: (i) Modified silica is prepared by the following method: 20 parts by weight of silica, 4 parts by weight of γ-aminopropyltriethoxysilane, 2 parts by weight of polyethylene glycol, 1 part by weight of toluenesulfonic acid, 0.5 parts by weight of alkyl glycoside and 55 parts by weight of deionized water are weighed and reacted in a reactor at 80°C for 2.5 hours to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, and then washed with deionized water and ethanol twice in sequence, centrifuged and placed in a vacuum drying oven at a temperature of 60°C for 5 hours, and cooled to room temperature to obtain modified silica. (ii) Preparation of modified carrier: γ-alumina (wherein the Al2O3 content in γ-alumina is greater than 98%, the Na2O content is less than 0.5%, and the Fe2O3 is less than 0.05%; the particle size of γ-alumina is 5-20μm, and the specific surface area is 260-320m 2 / g) and modified silica were mixed at a ratio of 20:1 and placed in a vacuum oven with a charge density of 1100 C / cm 3 , a plasma device with a gas flow rate of 1.3 L / min, a pressure of 90 kPa, and a temperature of 50°C for treatment for 5 minutes to obtain a pretreated carrier; 35 parts by weight of the pretreated carrier, 5 parts by weight of an auxiliary agent (the auxiliary agent is cerium nitrate and zirconium nitrate composed of a mass ratio of 2:1), 2 parts by weight of a surfactant (alkyl glycoside and 2,5-furan dimethanol composed of a mass ratio of 1:2), and 50 parts by weight of deionized water are weighed and placed in an ultrasonic device with a frequency of 85 Hz and a temperature of 45°C for treatment for 18 minutes, then filtered and dried in a drying oven at 50°C for 5 hours to obtain a pretreated modified carrier; the pretreated modified carrier is calcined at 450°C under vacuum conditions for 4 hours and then cooled to obtain a modified carrier.

[0031] S2. Preparation of precursor solution: Weigh 15 parts by weight of palladium chloride and 50 parts by weight of 60% nitric acid solution and stir at 55°C until all soluble salts of palladium metal are dissolved to obtain an active palladium metal precursor solution.

[0032] S3. Preparation of finished combustion aid: Weigh 60 parts by weight of the modified carrier and 28 parts by weight of the active palladium metal precursor solution, and place them in an ultrasonic device with a frequency of 90 Hz and a temperature of 45°C for treatment for 30 minutes to obtain a mixture; spray-dry the mixture in a spray drying device with a spray drying pressure of 2.5 MPa, a feed rate of 10 kg / h, an inlet air temperature of 120°C, and an exhaust air temperature of 75°C, and then place it in a muffle furnace. Under a nitrogen atmosphere, heat the temperature to 450°C at a heating rate of 5°C / min and maintain it for 2.5 hours to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor, and introduce a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 at a flow rate of 30 mL / min, and reduce it at 300°C for 2 hours to obtain a finished combustion aid.

[0033] Example 2:

[0034] The preparation method of palladium-type carbon monoxide combustion improver comprises the following preparation steps: S1. Preparation of modified carrier: (i) Modified silica is prepared by the following method: 25 parts by weight of silica, 6 parts by weight of γ-aminopropyltriethoxysilane, 4 parts by weight of polyethylene glycol, 3 parts by weight of toluenesulfonic acid, 1.0 part by weight of alkyl glycoside, and 60 parts by weight of deionized water are weighed and reacted in a reactor at 85°C for 2.0 hours to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, and then washed with deionized water and ethanol twice in sequence, centrifuged, and then dried in a vacuum drying oven at 70°C for 4 hours, and cooled to room temperature to obtain modified silica. (ii) Preparation of modified carrier: γ-alumina (of which The Al2O3 content in alumina is >98%, the Na2O content is <0.5%, and the Fe2O3 is <0.05%; the particle size of γ-alumina is 5-20μm, and the specific surface area is 260-320m 2 / g) and modified silica were mixed at a ratio of 25:1 and placed in a vacuum oven with a charge density of 1200 C / cm 3 , a plasma device with a gas flow rate of 1.6 L / min, a pressure of 100 kPa, and a temperature of 60°C for treatment for 5 minutes to obtain a pretreated carrier; 40 parts by weight of the pretreated carrier, 8 parts by weight of the auxiliary agent (the auxiliary agent is cerium nitrate and zirconium nitrate composed of a mass ratio of 2:1), 4 parts by weight of the surfactant (alkyl glycoside and 2,5-furan dimethanol composed of a mass ratio of 1:3), and 60 parts by weight of deionized water are weighed and placed in an ultrasonic device with a frequency of 90 Hz and a temperature of 50°C for treatment for 15 minutes, then filtered and dried in a drying oven at 60°C for 4 hours to obtain a pretreated modified carrier; the pretreated modified carrier is calcined at 500°C under vacuum conditions for 3 hours and then cooled to obtain a modified carrier.

[0035] S2. Preparation of precursor solution: Weigh 20 parts by weight of a soluble palladium metal salt (palladium nitrate and palladium acetate in a mass ratio of 1:1) and 60 parts by weight of a 65% nitric acid solution, and stir them at 60°C until the soluble palladium metal salt is completely dissolved to obtain an active palladium metal precursor solution.

[0036] S3. Preparation of finished combustion aid: Weigh 70 parts by weight of the modified carrier and 32 parts by weight of the active palladium metal precursor solution, place them in an ultrasonic device with a frequency of 100 Hz and a temperature of 50°C for treatment for 25 minutes to obtain a mixture; spray-dry the mixture in a spray drying device with a spray drying pressure of 2.8 MPa, a feed rate of 11 kg / h, an inlet air temperature of 125°C and an exhaust air temperature of 80°C, and place it in a muffle furnace. Under a nitrogen atmosphere, heat the temperature to 500°C at a heating rate of 5°C / min and maintain it for 2.0 hours to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor, introduce a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 at a flow rate of 30 mL / min, and reduce it at 320°C for 1.5 hours to obtain a finished combustion aid.

[0037] Example 3:

[0038] The preparation method of palladium-type carbon monoxide combustion improver comprises the following preparation steps: S1. Preparation of modified carrier: (i) Modified silica is prepared by the following method: 22 parts by weight of silica, 5 parts by weight of γ-aminopropyltriethoxysilane, 3 parts by weight of polyethylene glycol, 2 parts by weight of toluenesulfonic acid, 0.8 parts by weight of alkyl glycoside and 58 parts by weight of deionized water are weighed and reacted in a reactor at 82°C for 2.0 hours to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, and then washed with deionized water and ethanol twice in sequence, centrifuged and placed in a vacuum drying oven at a temperature of 65°C for 4.5 hours, and cooled to room temperature to obtain modified silica. (ii) Preparation of modified carrier: γ-alumina (wherein the Al2O3 content in γ-alumina is greater than 98%, the Na2O content is less than 0.5%, and the Fe2O3 is less than 0.05%; the particle size of γ-alumina is 5 to 20 μm, and the specific surface area is 260 to 320 m 2 / g) and modified silica were mixed at a ratio of 22:1 and placed in a chamber with a charge density of 1150 C / cm 3 , a plasma device with a gas flow rate of 1.5 L / min, a pressure of 95 kPa, and a temperature of 55°C for treatment for 4.5 minutes to obtain a pretreated carrier; 36 parts by weight of the pretreated carrier, 6 parts by weight of the auxiliary agent (the auxiliary agent is cerium nitrate and zirconium nitrate composed of a mass ratio of 2:1), 3 parts by weight of the surfactant (alkyl glycoside and 2,5-furan dimethanol composed of a mass ratio of 1:2), and 55 parts by weight of deionized water are weighed and placed in an ultrasonic device with a frequency of 88 Hz and a temperature of 48°C for treatment for 16 minutes, then filtered and dried in a drying oven at 55°C for 4.5 hours to obtain a pretreated modified carrier; the pretreated modified carrier is calcined at 480°C under vacuum conditions for 3.5 hours and then cooled to obtain a modified carrier.

[0039] S2. Preparation of precursor solution: Weigh 18 parts by weight of palladium nitrate and 55 parts by weight of 62% nitric acid solution and stir at 58°C until all soluble salts of palladium metal are dissolved to obtain an active palladium metal precursor solution.

[0040] S3. Preparation of finished combustion aid: Weigh 65 parts by weight of the modified carrier and 30 parts by weight of the active palladium metal precursor solution, and place them in an ultrasonic device with a frequency of 95 Hz and a temperature of 48°C for treatment for 28 minutes to obtain a mixture; spray-dry the mixture in a spray drying device with a spray drying pressure of 2.6 MPa, a feed rate of 10 kg / h, an inlet air temperature of 120°C, and an exhaust air temperature of 78°C, and then place it in a muffle furnace. Under a nitrogen atmosphere, heat the temperature to 460°C at a heating rate of 5°C / min and maintain it for 2.0 hours to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor, and introduce a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 at a flow rate of 30 mL / min, and reduce it at 310°C for 2 hours to obtain a finished combustion aid.

[0041] Comparative Example 1: The difference from Example 1 is that the modified silicon dioxide is removed.

[0042] Comparative Example 2: The difference from Example 1 is that the silicon dioxide is not modified.

[0043] Comparative Example 3: The difference from Example 1 is that 2 parts by weight of the surfactant (alkyl glycoside and 2,5-furan dimethanol in a mass ratio of 1:2) in S1 is replaced by 2 parts by weight of alkyl glycoside.

[0044] Comparative Example 4: The difference from Example 1 is that 2 parts by weight of the surfactant (alkyl glycoside and 2,5-furan dimethanol in a mass ratio of 1:2) in S1 is replaced by 2 parts by weight of 2,5-furan dimethanol.

[0045] Comparative Example 5: The difference from Example 1 is that γ-alumina and modified silicon dioxide are evenly mixed at a ratio of 9:1 and then not subjected to plasma treatment.

[0046] The performance of a palladium-type carbon monoxide combustion improver prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5 was tested.

[0047] The active component content was determined by spectrophotometry; the specific surface area was tested according to the "Determination of specific surface area - Nitrogen adsorption method" GB / T6609.35-2009; and the wear index was tested according to the "Determination of wear index" GB / T6609.33-2009, as shown in Table 1.

[0048] Table 1: Palladium type carbon monoxide combustion aid performance test table

[0049] As shown in Table 1, the active component content of the carbon monoxide combustion-supporting agent in the embodiment is between 0.052 and 0.058%, and the specific surface area is between 190 and 202 m 2 / g, and the wear index is between 3.25 and 3.60%. The active component content and specific surface area of ​​the carbon monoxide combustion-supporting agent in the comparative example are lower than those in the example, and the wear index is higher than that in the example.

[0050] During the preparation of carbon monoxide combustion improver, the carrier is modified to improve the adsorption capacity of the active component palladium metal. The combination of alumina and modified silica optimizes the support's pore structure, including pore size distribution and specific surface area. γ-alumina maintains structural stability at high temperatures and is less susceptible to phase transitions. This effectively resists high-temperature damage to the support structure, reduces wear, and ensures that the combustion improver maintains rapid performance degradation over long-term use. The addition of modified silica significantly improves the support's mechanical strength and wear resistance, reducing wear and breakage of the combustion improver during the catalytic reaction and extending the catalyst's service life. During calcination, 2,5-furan dimethanol crosslinks the modified support through hydroxyl condensation reactions, forming a denser network structure and enhancing the support's mechanical strength, including wear and impact resistance. Alkyl glycosides promote uniform dispersion of active components through their surface activity, while 2,5-furan dimethanol firmly anchors the dispersed active components to the support surface through coordination and hydrogen bonding. The combination significantly reduces active component agglomeration and increases the specific surface area of ​​the modified support. The high-energy particles in the plasma can activate the aluminum hydroxyl (Al-OH) on the surface of γ-alumina and the silanol (Si-OH) on the surface of modified silica, causing a dehydration condensation reaction between the two at the interface to form Al-O-Si bonds, thereby improving the overall mechanical strength of the modified carrier.

[0051] The palladium-type carbon monoxide combustion improver was prepared using Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4 and 5, and the evaluation of the combustion improver was performed on a riser catalytic cracking simulation device. The catalyst used was a balance agent from a petrochemical catalytic cracking device. 10 kg of balance agent was weighed, and 100 g of each palladium-type carbon monoxide combustion improver prepared using Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4 and 5 was fully mixed with the 10 kg balance agent, and then added to the regenerator of the riser catalytic cracking simulation device. The raw material was coker gas oil, temperature: 525 ° C, regenerator temperature: 660 ° C, pressure: 0.15 MPa, catalyst-oil ratio: 6.5, and main air volume 2500 NL / h. After the simulation device was operating normally, flue gas was taken for detection at 12 h.

[0052] Table 2: Evaluation table of palladium-type carbon monoxide combustion aid

[0053] As shown in Table 2, the palladium type carbon monoxide combustion improver prepared in the embodiment has a carbon monoxide conversion rate between 96.4% and 98.6%, which is higher than that of the comparative example. The carbon monoxide conversion rates of the palladium type carbon monoxide combustion improver prepared in Comparative Examples 1, 2, 3, 4 and 5 are 15.6%, 11.4%, 8.5%, 13.1% and 11.2% lower than those in Example 1, respectively; the increase in nitrogen monoxide of the palladium type carbon monoxide combustion improver prepared in the embodiment is between 21 and 25 ppm, which is lower than that of the comparative example. The increase in nitrogen monoxide of the palladium type carbon monoxide combustion improver prepared in Comparative Examples 1, 2, 3, 4 and 5 is 147.6%, 104.8%, 61.9%, 95.2% and 81.0% higher than that in Example 1, respectively.

[0054] Mixing γ-alumina and modified silica can optimize the pore structure of the carrier, such as pore size distribution and specific surface area, improve mass transfer efficiency, reduce the diffusion resistance of reactants, improve reaction activity and catalytic efficiency, thereby increasing CO conversion rate and reducing NO X Content. γ-alumina has a high specific surface area, fine particle size and rich void structure, which can provide sufficient attachment sites for the active component palladium of the combustion support, increase the contact area between the active component palladium and carbon monoxide, and improve the efficiency of the combustion support reaction. Moreover, the hydroxyl group (-OH) on the surface of γ-alumina can form a stable chemical bond with the active component palladium, which can not only avoid the loss of the active component during the reaction, but also regulate the redox properties of the active component through electronic effects, and enhance its catalytic oxidation ability for carbon monoxide. The surface of silica modified with γ-aminopropyltriethoxysilane carries a positive charge, and the palladium particles can be evenly dispersed through electrostatic repulsion, narrowing the particle size distribution and exposing more palladium active sites, thereby improving the activity of the combustion support, increasing the CO conversion rate, and reducing NO X content. During the preparation of the modified carrier, alkyl glycoside guides the formation of pores through self-assembly, optimizes the pore size distribution of γ-alumina / modified silica, enhances the diffusion efficiency of gases (CO, O2, etc.) inside the carrier, provides sufficient mass transfer channels for the CO oxidation reaction, and thus improves the CO conversion rate. The introduction of 2,5-furan dimethanol can adjust the hydrophilicity and acidity and alkalinity of the carrier surface. The hydrophobicity of the furan ring can reduce the adsorption of water vapor by the carrier and avoid hydration inactivation, while the weak polarity of the hydroxyl group can enhance the adsorption capacity of CO molecules, promote the enrichment and activation of CO at active sites, and improve the CO conversion rate. The high-energy particles in the plasma can remove impurities such as oil stains and organic residues remaining on the carrier surface through collision, decompose chemically adsorbed hydrocarbon chains and other inert groups, expose more active sites, improve the activity of the flame retardant, and increase the CO conversion rate.

[0055] In summary, the palladium-type carbon monoxide combustion improver prepared by the present invention has high activity, can improve the carbon monoxide conversion rate, reduce the nitrogen oxide content, and has a simple preparation method, and is suitable for large-scale promotion and use.

[0056] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all included in the scope of protection of the present invention.

Claims

1. A method for preparing a palladium-type carbon monoxide combustion improver, characterized in that: The method comprises the following preparation steps: S1. Preparation of modified support: γ-alumina and modified silica were mixed at a ratio of 20 to 25:1 and then placed in a plasma device for 4 to 5 minutes to obtain a pretreated support; 35 to 40 parts by weight of the pretreated support, 5 to 8 parts by weight of an additive, 2 to 4 parts by weight of a surfactant, and 50 to 60 parts by weight of deionized water were weighed and placed in an ultrasonic device at a frequency of 85 to 90 Hz and a temperature of 45 to 50 ° C for 15 to 18 minutes, filtered, and dried in a drying oven at 50 to 60 ° C for 4 to 5 hours to obtain a pretreated modified support; The pretreated modified carrier is calcined at 450-500° C. under vacuum conditions for 3-4 hours and then cooled to obtain a modified carrier; S2. Preparation of a precursor solution: Weigh 15 to 20 parts by weight of a soluble palladium metal salt and 50 to 60 parts by weight of a nitric acid solution having a concentration of 60 to 65% and stir at 55 to 60 ° C until the soluble salt of the palladium metal is completely dissolved to obtain an active palladium metal precursor solution; S3. Preparation of finished combustion aid: Weigh 60-70 parts by weight of a modified carrier and 28-32 parts by weight of an active palladium metal precursor solution, and place them in an ultrasonic device at a frequency of 90-100 Hz and a temperature of 45-50°C for treatment for 25-30 minutes to obtain a mixture; spray-dry the mixture in a spray drying device and place it in a muffle furnace. Under a nitrogen atmosphere, heat the mixture at a heating rate of 5°C / min to 450-500°C and maintain it for 2.0-2.5 hours to obtain a semi-finished combustion aid; place the semi-finished combustion aid in a reactor and reduce it at 300-320°C for 1.5-2.0 hours to obtain a finished combustion aid.

2. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The modified silicon dioxide is prepared by the following method: Step 1: Weigh 20-25 parts by weight of silica, 4-6 parts by weight of γ-aminopropyltriethoxysilane, 2-4 parts by weight of polyethylene glycol, 1-3 parts by weight of toluenesulfonic acid, 0.5-1.0 parts by weight of alkyl glycoside, and 55-60 parts by weight of deionized water in a reactor at 80-85° C. for 2.0-2.5 hours to obtain a pretreated silica mixture; Step 2: Filter the pretreated silica mixture, wash it with deionized water and ethanol twice, centrifuge it, dry it in a vacuum drying oven at 60-70°C for 4-5 hours, and cool it to room temperature to obtain modified silica.

3. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The surfactant is composed of alkyl glycoside and 2,5-furan dimethanol in a mass ratio of 1:2-3.

4. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The charge density of the plasma equipment is 1100-1200 C / cm 3 , gas flow rate is 1.3~1.6L / min, pressure is 90~100kPa, and temperature is 50~60℃.

5. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The auxiliary agent is composed of cerium nitrate and zirconium nitrate in a mass ratio of 2:

1.

6. The preparation method of the palladium type carbon monoxide combustion improver according to claim 1, wherein The soluble salt of palladium metal is any one of palladium chloride, palladium nitrate, palladium acetate, or a mixture of two substances.

7. The preparation method of the palladium type carbon monoxide combustion improver according to claim 1, wherein The spray drying pressure is 2.5-2.8 MPa, the feed rate is 10-11 kg / h, the inlet air temperature is 120-125° C., and the exhaust air temperature is 75-80° C.

8. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein When the combustion-supporting agent semi-finished product reacts in the reactor, a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 is introduced at a flow rate of 30 mL / min.

9. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The Al2O3 content of the γ-alumina is greater than 98%, the Na2O content is less than 0.5%, and the Fe2O3 content is less than 0.05%. The particle size of the γ-alumina is 5 to 20 μm, and the specific surface area is 260 to 320 m 2 / g.

10. Palladium type carbon monoxide combustion improver, characterized in that, The compound is prepared by the preparation method according to any one of claims 1 to 9.

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