Palladium type carbon monoxide combustion improver and method for producing the same

Abstract

The application 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-alumina and modified silicon dioxide, and the active component is a palladium metal. The preparation steps are as follows: S1. modified carrier preparation: after plasma treatment of gamma-alumina and modified silicon dioxide, additives, a surfactant and deionized water are added, ultrasonic treatment, drying and calcination are carried out; S2. preparation of a precursor solution: a soluble salt of the palladium metal is mixed with a nitric acid solution and dissolved; S3. preparation of a combustion improver finished product: the modified carrier and the active palladium metal precursor solution are ultrasonically treated, spray dried, kept at 450-500 DEG C, and reduced at 300-320 DEG C to obtain the combustion improver finished product. The palladium type carbon monoxide combustion improver prepared by the application has high activity, can improve the carbon monoxide conversion rate, reduce the content of nitrogen oxides, and has a simple preparation method and is suitable for large-scale popularization and use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum chemical combustion improver, in particular to a palladium type carbon monoxide combustion improver and a preparation method thereof. BACKGROUND

[0002] In the production process of light oil, the cracking of macromolecular hydrocarbons will produce coke attached to the surface and pores of the catalytic cracking catalyst, reducing the activity of the catalyst. The coked catalyst is in contact with oxygen-containing gas under high temperature conditions, and the deposited coke is converted into carbon monoxide (CO) and carbon dioxide (CO2) gas. These COs are discharged with flue gas, which pollutes the environment. If the catalyst is taken to the dilute phase bed layer in the upper part of the regenerator, it will further burn and release a large amount of heat, causing the structure and performance of the catalyst in this section to be damaged, and also causing damage to the equipment, thereby affecting the progress of the catalytic cracking reaction of petroleum.

[0003] The flue gas generated in the process of petroleum catalytic cracking (FCC) contains CO and NO X (harmful gases), which can cause environmental pollution and affect the production of light oil. In order to solve this technical problem, relevant researchers usually add a carbon monoxide combustion improver to the catalyst to increase the CO reaction rate, convert CO to CO2 in the dense phase of the regenerator, realize heat recycling, reduce CO emissions, and thus reduce environmental pollution.

[0004] Carbon monoxide combustion improver is an additive in the catalytic cracking process in the field of petroleum chemical industry. It can convert CO in the flue gas of the regenerator into CO2, and at the same time reduce the generation of NO X , so as to save energy consumption, increase the yield of light oil, and reduce environmental pollution.

[0005] The addition of the carbon monoxide combustion improver on the market reduces the CO content in the flue gas while increasing the NO content. The carrier used is usually ordinary alumina or silicon oxide, which has a small number of active sites and low activity, and is easy to be inactivated during high temperature use, which is difficult to meet the production demand.

[0006] Therefore, improving the activity of the carbon monoxide combustion improver, increasing the CO conversion, and reducing the NO X content are technical problems that need to be solved in the petroleum chemical industry. SUMMARY

[0007] The present application aims to provide a palladium type carbon monoxide combustion improver and a preparation method thereof, to solve the problems of low activity of the carbon monoxide combustion improver, low CO conversion rate, and high NO X content in the background art.

[0008] In a first aspect, the present application provides a palladium type carbon monoxide combustion improver, comprising a modified carrier and an active component; wherein the modified carrier is prepared by mixing γ-alumina and modified silicon dioxide, then treating in a plasma device, adding an auxiliary agent, a surfactant and deionized water, ultrasonic treatment, drying and vacuum calcination; the active component is palladium metal; and the active component is carried on the modified carrier.

[0009] In a second aspect, the present application provides a preparation method of the palladium type carbon monoxide combustion improver, comprising the following preparation steps:

[0010] S1. Preparation of a modified carrier: uniformly mix γ-alumina and modified silicon dioxide at a ratio of 20-25:1, then treat in a plasma device for 4-5 min to obtain a pretreated carrier; weigh 35-40 parts by weight of the pretreated carrier, 5-8 parts by weight of an auxiliary agent, 2-4 parts by weight of a surfactant and 50-60 parts by weight of deionized water, and then place them in an ultrasonic device with a frequency of 85-90 Hz and a temperature of 45-50℃ for 15-18 min, filter, dry in a 50-60℃ drying box for 4-5 h to obtain a pretreated modified carrier; and then calcine the pretreated modified carrier at 450-500℃ under vacuum for 3-4 h, and cool to obtain the modified carrier.

[0011] S2. Preparation of a precursor solution: weigh 15-20 parts by weight of a soluble salt of palladium metal and 50-60 parts by weight of a 60-65% mass concentration nitric acid solution, and then stir at 55-60℃ until the soluble salt of palladium metal is completely dissolved to obtain an active palladium metal precursor solution.

[0012] S3. Preparation of a combustion improver product: weigh 60-70 parts by weight of the modified carrier and 28-32 parts by weight of the active palladium metal precursor solution, and then place them in an ultrasonic device with a frequency of 90-100 Hz and a temperature of 45-50℃ for 25-30 min to obtain a mixture; spray dry the mixture in a spray drying device, and then place it in a muffle furnace, heat to 450-500℃ at a heating rate of 5℃ / min under a nitrogen atmosphere, and then maintain the temperature for 2.0-2.5 h to obtain a combustion improver semi-product; and then place the combustion improver semi-product in a reactor, and reduce it at 300-320℃ for 1.5-2.0 h to obtain the combustion improver product.

[0013] As a preferred technical solution of the present application, the modified silicon dioxide is prepared by the following method:

[0014] Step one: weigh 20-25 parts by weight of silicon dioxide, 4-6 parts by weight of γ-aminopropyl triethoxysilane, 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 polyglycoside and 55-60 parts by weight of deionized water, and then react in a 80-85℃ reaction kettle for 2.0-2.5 h to obtain a pretreated silicon dioxide mixture.

[0015] Step two: filter the pretreated silica dioxide mixture, then wash with 2 times of deionized water and ethanol, centrifugal treatment, and then dry in a vacuum drying oven at 60-70 DEG C for 4-5h, cool to room temperature, to obtain modified silica dioxide.

[0016] As a preferred technical solution of the present application, the surfactant is composed of alkyl glycoside and 2, 5-furan dimethyl alcohol with a mass ratio of 1:2-3.

[0017] As a preferred technical solution of the present application, the plasma device charge density is 1100-1200C / cm 3 , the gas flow is 1.3-1.6L / min, the pressure is 90-100kPa, and the temperature is 50-60 DEG C.

[0018] As a preferred technical solution of the present application, the auxiliary agent is composed of cerium nitrate and zirconium nitrate with a mass ratio of 2:1.

[0019] As a preferred technical solution of the present application, the soluble salt of palladium metal is any one of palladium chloride, palladium nitrate and palladium acetate or a mixture of two substances.

[0020] As a preferred technical solution of the present application, the spray drying pressure is 2.5-2.8MPa, the feeding speed is 10-11kg / h, the inlet air temperature is 120-125 DEG C, and the exhaust air temperature is 75-80 DEG C.

[0021] As a preferred technical solution of the present application, when the combustion-supporting agent semi-finished product is reacted in the reactor, a mixed gas of hydrogen and nitrogen with a flow ratio of 1:8 is passed at a flow rate of 30mL / min.

[0022] As a preferred technical solution of the present application, the Al2O3 content of the gamma-alumina is >98%, the Na2O content is <0.5%, and the Fe2O3 is <0.05%; the particle size of the gamma-alumina is 5-20μm, and the specific surface area is 260-320m 2 / g.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1、The palladium metal active carrier used in the present application is a modified carrier prepared by mixing gamma-alumina and modified silica dioxide, and the gamma-alumina has a specific surface area of 260-320m 2The high specific surface area of 1000-1500 m2 / g, the small particle size of 5-20 μm, and the rich void structure of the modified carrier can provide sufficient attachment sites for the active component palladium of the combustion improver, so that the active component palladium is uniformly dispersed, the contact area between the active component palladium and carbon monoxide is increased, and the efficiency of the combustion reaction is improved. The hydroxyl groups (-OH) on the surface of the γ-alumina can form stable chemical bonds (such as palladium-oxygen-aluminum bonds) with the active component palladium, which can not only avoid the loss of the active component in the reaction, but also can adjust the redox performance of the active component through the electronic effect, enhance the catalytic oxidation ability of the active component to carbon monoxide, and realize the synergistic effect of the carrier and the active component. In addition, the γ-alumina can maintain structural stability under high temperature conditions and is not prone to phase change, which can effectively resist the destruction of the carrier structure by high temperature and ensure that the performance of the combustion improver will not rapidly decay in the long-term use process. The addition of the modified silica further improves the thermal stability of the carrier, so that the modified carrier can maintain good performance under high temperature environment. The γ-alumina has a rich mesoporous structure and a high specific surface area, which can provide sufficient active component loading sites. The addition of the modified silica can improve the mechanical strength and wear resistance of the carrier, reduce the wear and breakage of the combustion improver in the catalytic reaction process, prolong the service life of the catalyst, and the modified silica can adjust the surface hydrophilicity or hydrophobicity or the acidic sites, make up for the defect that the surface of the γ-alumina is too alkaline, and enhance the chemical stability of the carrier. The mixing of the γ-alumina and the modified silica can optimize the pore structure of the carrier such as the pore size distribution and the specific surface area, improve the mass transfer efficiency, reduce the diffusion resistance of the reactants, improve the reaction activity and catalytic efficiency, and thus improve the CO conversion rate and reduce the NO X content.

[0025] 2. The surface of the modified silica is rich in silicon hydroxyl groups (Si-OH) and silicon oxygen bonds (Si-O-Si), which can introduce active functional groups such as amino groups and carboxyl groups through chemical modification, enhance the bonding force with palladium particles, and prevent palladium particle agglomeration. The modified silica can form Pd-O-Si bonds with palladium, reduce the oxidation state stability of palladium, promote the reduction reaction, and thus improve the catalytic activity of the combustion improver. The silanol groups (Si-OH) generated after the hydrolysis of γ-aminopropyl triethoxysilane can react with the hydroxyl groups on the surface of the silica to form covalent bonds, and at the same time expose amino groups (-NH2); as a strong coordination group, the amino group can efficiently anchor palladium ions (Pd 2+ ), form stable Pd-N coordination bonds, prevent palladium from migrating or sintering in the reduction process and affecting the activity, and the surface of the silica modified by γ-aminopropyl triethoxysilane is positively charged, which can uniformly disperse palladium particles through electrostatic repulsion, narrow the particle size distribution, and expose more palladium active sites, thereby improving the activity of the combustion improver, improving the CO conversion rate, and reducing the 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.

[0026] 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+) Coordination occurs, the anchoring strength of active components on the surface of the carrier is improved, sintering or shedding of active components at high temperature is reduced, and the life of the combustion improver is prolonged; at the same time, the introduction of 2,5-furan dimethyl alcohol can adjust the hydrophilicity and hydrophobicity and the acidity and alkalinity of the surface of the carrier, the hydrophobic property of the furan ring can reduce the adsorption of water vapor by the carrier, and hydration deactivation is avoided, 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 site, and improve the CO conversion rate; in addition, 2,5-furan dimethyl alcohol can participate in the crosslinking of the modified carrier through the hydroxyl condensation reaction in the calcination process, forming a more compact 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 dimethyl alcohol has high temperature resistance, which can reduce the structural damage of the carrier at high temperature. Alkyl glycoside promotes uniform dispersion of active components through surface activity, and 2,5-furan dimethyl alcohol firmly anchors the dispersed active components on the surface of the carrier through coordination and hydrogen bonding, and the combination of the two can significantly reduce the agglomeration of active components and improve the specific surface area of the modified carrier. Alkyl glycoside as a soft template can regulate the carrier to form abundant mesopores, and the crosslinking of 2,5-furan dimethyl alcohol can stabilize the pore structure to form a carrier with "high porosity + appropriate pore size distribution", which reduces the diffusion resistance of CO and O2 in the carrier and improves the combustion reaction rate.

[0027] 4、In the preparation process of the modified carrier, γ-alumina and modified silica are subjected to plasma treatment. High-energy particles in the plasma can remove impurities such as oil stains and organic residues on the surface of the carrier through collision, decompose inert groups such as chemisorbed carbon-hydrogen chains, expose more active sites, improve the activity of the flame retardant, and improve the CO conversion rate; moreover, the high-energy particles in the plasma can oxidize the surface of the carrier, increase the density of oxygen-containing functional groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH), and improve the loading amount of active components; in addition, the high-energy impact of the plasma can break the van der Waals force and other weak binding forces between particles, unblock the blocked mesopores, and make the pore size distribution more concentrated; furthermore, the high-energy particles in the plasma can activate the aluminum hydroxyl groups (Al-OH) on the surface of γ-alumina and the silicon hydroxyl groups (Si-OH) on the surface of the modified silica, so that dehydration condensation reaction occurs at the interface to form Al-O-Si bonds, and the overall mechanical strength of the modified carrier is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The preparation flow chart of the palladium type carbon monoxide combustion improver of the present application is shown. DETAILED DESCRIPTION

[0029] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0030] As Figure 1 The preparation method of the palladium type carbon monoxide combustion improver of the present application is shown in the figure, which comprises the following preparation steps: S1. Preparation of modified carrier: (1) The modified silica is prepared by the following method: silica, γ-aminopropyl triethoxysilane, polyethylene glycol, toluenesulfonic acid, alkyl glycoside, and deionized water are reacted in a 80-85℃ reaction kettle for 2.5h to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, then washed with 2 times of deionized water and ethanol, centrifuged, and then placed in a vacuum drying oven at a temperature of 60℃ for drying, and cooled to room temperature to obtain modified silica. (2) Preparation of modified carrier: the γ-alumina and the modified silica are mixed uniformly and then placed in a plasma device for treatment to obtain a pretreated carrier; the pretreated carrier, an auxiliary agent, a surfactant, and deionized water are placed in an ultrasonic device for treatment, then filtered and dried to obtain a pretreated modified carrier; the pretreated modified carrier is calcined under vacuum and cooled to obtain a modified carrier. S2. Preparation of precursor solution: a soluble salt of palladium metal is stirred and dissolved in nitric acid solution to obtain an active palladium metal precursor solution. S3. Preparation of combustion improver finished product: the modified carrier and the active palladium metal precursor solution are placed in an ultrasonic device for treatment, then spray dried and placed in a muffle furnace, and heated at 450-500℃ under a nitrogen atmosphere to obtain a combustion improver semi-finished product; the combustion improver semi-finished product is placed in a reactor, and a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 is introduced at a flow rate of 30mL / min, and then reduced at 300-320℃ to obtain a combustion improver finished product.

[0031] The raw materials used in the present application are all commercially available.

[0032] Example 1:

[0033] The preparation method of the palladium type carbon monoxide combustion improver comprises the following preparation steps:

[0034] S1. Preparation of modified carrier: (1) The modified silica was prepared by the following method: 20 parts by weight of silica, 4 parts by weight of γ-aminopropyl triethoxysilane, 2 parts by weight of polyethylene glycol, 1 part by weight of toluenesulfonic acid, 0.5 parts by weight of alkyl polyglycoside, and 55 parts by weight of deionized water were weighed and reacted in a 80℃ reaction kettle for 2.5h to obtain a pretreated silica mixture; the pretreated silica mixture was filtered, then washed with deionized water and ethanol in turn, centrifuged, and then placed in a vacuum drying oven at a temperature of 60℃ for drying for 5h, and cooled to room temperature to obtain the modified silica. (2) Preparation of modified carrier: γ-alumina (wherein the content of Al2O3 in the γ-alumina is >98%, the content of Na2O is <0.5%, and the content of Fe2O3 is <0.05%; the particle size of the γ-alumina is 5-20μm, and the specific surface area is 260-320m 2 / g) and the modified silica were mixed uniformly at a ratio of 20:1, and then placed in a plasma device with a charge density of 1100C / cm 3 , a gas flow rate of 1.3L / min, a pressure of 90kPa, and a temperature of 50℃ for 5min to obtain a pretreated carrier; 35 parts by weight of the pretreated carrier, 5 parts by weight of an additive (the additive is composed of cerium nitrate and zirconium nitrate at a mass ratio of 2:1), and 2 parts by weight of a surfactant (composed of alkyl polyglycoside and 2,5-furandimethanol at a mass ratio of 1:2), and 50 parts by weight of deionized water were placed in an ultrasonic device with a frequency of 85Hz and a temperature of 45℃ for 18min, then filtered and dried in a 50℃ drying oven for 5h to obtain a pretreated modified carrier; the pretreated modified carrier was calcined at 450℃ under vacuum for 4h and then cooled to obtain the modified carrier.

[0035] S2. Preparation of precursor solution: 15 parts by weight of palladium chloride and 50 parts by weight of 60% mass concentration nitric acid solution were weighed and stirred at 55℃ until the soluble salt of palladium metal was completely dissolved to obtain an active palladium metal precursor solution.

[0036] S3. Preparation of combustion improver finished product: 60 parts by weight of modified carrier and 28 parts by weight of active palladium metal precursor solution were placed in an ultrasonic device with a frequency of 90Hz and a temperature of 45℃ for 30min to obtain a mixture; the mixture was sprayed and dried in a spray drying device with a pressure of 2.5MPa, a feeding speed of 10kg / h, an inlet air temperature of 120℃, and an exhaust air temperature of 75℃, and then placed in a muffle furnace, under a nitrogen atmosphere, and heated to 450℃ at a heating rate of 5℃ / min, and then kept for 2.5h to obtain a combustion improver semi-finished product; the combustion improver semi-finished product was placed in a reactor, and a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 was introduced at a flow rate of 30mL / min, and then reduced at 300℃ for 2h to obtain a combustion improver finished product.

[0037] Example Two:

[0038] The preparation method of the palladium type carbon monoxide combustion improver comprises the following preparation steps:

[0039] S1. Modification carrier preparation: (1) The modified silica is prepared by the following method: 25 parts by weight of silica, 6 parts by weight of γ-aminopropyl triethoxysilane, 4 parts by weight of polyethylene glycol, 3 parts by weight of toluenesulfonic acid, 1.0 parts by weight of alkyl polyglycoside and 60 parts by weight of deionized water are weighed and reacted in a 85℃ reaction kettle for 2.0h to obtain a pretreated silica mixture; the pretreated silica mixture is filtered, then washed with deionized water and ethanol in turn, centrifuged and then placed in a vacuum drying oven at a temperature of 70℃ for drying for 4h, and cooled to room temperature to obtain modified silica. (2) Modification carrier preparation: γ-alumina (wherein The content of Al2O3 in the alumina is >98%, the content of Na2O is <0.5%, and the content of Fe2O3 is <0.05%; the particle size of the γ-alumina is 5-20μm, and the specific surface area is 260-320m 2 / g) and the modified silica are uniformly mixed at a ratio of 25:1, and then placed in a plasma device with a charge density of 1200C / cm 3 , a gas flow of 1.6L / min, a pressure of 100kPa and a temperature of 60℃ for 5min to obtain a pretreated carrier; 40 parts by weight of the pretreated carrier, 8 parts by weight of an additive (the additive is composed of cerium nitrate and zirconium nitrate at a mass ratio of 2:1), 4 parts by weight of a surfactant (composed of alkyl polyglycoside and 2,5-furandimethanol at a mass ratio of 1:3) and 60 parts by weight of deionized water are placed in an ultrasonic device with a frequency of 90Hz and a temperature of 50℃ for 15min, then filtered and dried in a 60℃ drying oven for 4h to obtain a pretreated modified carrier; the pretreated modified carrier is calcined at 500℃ under vacuum conditions for 3h and then cooled to obtain a modified carrier.

[0040] S2. Preparation of precursor solution: 20 parts by weight of a soluble salt of palladium metal (consisting of palladium nitrate and palladium acetate at a mass ratio of 1:1) and 60 parts by weight of a 65% mass concentration nitric acid solution are stirred at 60℃ until the soluble salt of palladium metal is completely dissolved to obtain an active palladium metal precursor solution.

[0041] S3. Preparation of combustion improver product: 70 parts by weight of modified carrier and 32 parts by weight of active palladium metal precursor solution were weighed into an ultrasonic device with a frequency of 100 Hz and a temperature of 50℃ and treated for 25 min to obtain a mixture; the mixture was spray dried 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℃, and an exhaust air temperature of 80℃, and then placed in a muffle furnace, under a nitrogen atmosphere, and heated to 500℃ at a heating rate of 5℃ / min and maintained for 2.0 h to obtain a combustion improver semi-product; the combustion improver semi-product was placed in a reactor, and a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 was passed through at a flow rate of 30 mL / min, and reduced at 320℃ for 1.5 h to obtain a combustion improver product.

[0042] Example Three:

[0043] The preparation method of the palladium type carbon monoxide combustion improver comprises the following preparation steps:

[0044] S1. Preparation of modified carrier: (1) The modified silica was prepared by the following method: 22 parts by weight of silica, 5 parts by weight of γ-aminopropyl triethoxysilane, 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 were weighed into a 82℃ reaction kettle and reacted for 2.0 h to obtain a pretreated silica mixture; the pretreated silica mixture was filtered, then washed with deionized water and ethanol in turn, centrifuged, and then placed in a vacuum drying oven at a temperature of 65℃ for drying for 4.5 h, and cooled to room temperature to obtain modified silica. (2) Preparation of modified carrier: the γ-alumina (wherein the content of Al2O3 in the γ-alumina is >98%, the content of Na2O is <0.5%, and the content of Fe2O3 is <0.05%; the particle size of the γ-alumina is 5-20 μm, and the specific surface area is 260-320 m 2 / g) and the modified silica were mixed uniformly in a ratio of 22:1, and then placed in a plasma device with a charge density of 1150 C / cm 3 , a gas flow rate of 1.5 L / min, a pressure of 95 kPa, and a temperature of 55℃ for 4.5 min to obtain a pretreated carrier; 36 parts by weight of the pretreated carrier, 6 parts by weight of an additive (the additive is composed of cerium nitrate and zirconium nitrate in a mass ratio of 2:1), 3 parts by weight of a surfactant (composed of alkyl glycoside and 2,5-furandimethanol in a mass ratio of 1:2), and 55 parts by weight of deionized water were weighed into an ultrasonic device with a frequency of 88 Hz and a temperature of 48℃ and treated for 16 min, then filtered and dried in a 55℃ drying oven for 4.5 h to obtain a pretreated modified carrier; the pretreated modified carrier was calcined under vacuum at 480℃ for 3.5 h and then cooled to obtain a modified carrier.

[0045] S2. Preparation of the precursor solution: 18 parts by weight of palladium nitrate and 55 parts by weight of a 62% by mass nitric acid solution were weighed and stirred at 58°C until the soluble salt of the palladium metal was completely dissolved, to obtain an active palladium metal precursor solution.

[0046] S3. Preparation of the combustion improver product: 65 parts by weight of the modified carrier and 30 parts by weight of the active palladium metal precursor solution were placed in an ultrasonic device with a frequency of 95 Hz and a temperature of 48°C for 28 min to obtain a mixture; the mixture was spray dried 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 placed in a muffle furnace under a nitrogen atmosphere, and heated to 460°C at a heating rate of 5°C / min and then maintained for 2.0 h to obtain a combustion improver semi-product; the combustion improver semi-product was placed in a reactor, and a mixed gas of hydrogen and nitrogen with a gas ratio of 1:8 was passed in at a flow rate of 30 mL / min, and reduced at 310°C for 2 h to obtain a combustion improver product.

[0047] Comparative Example 1:

[0048] The difference from Example 1 is that the modified silicon dioxide is removed.

[0049] Comparative Example 2:

[0050] The difference from Example 1 is that the silicon dioxide is not modified.

[0051] Comparative Example 3:

[0052] The difference from Example 1 is that 2 parts by weight of the surfactant (consisting of alkyl glycoside and 2,5-furandimethanol at a mass ratio of 1:2) in S1 is replaced by 2 parts by weight of alkyl glycoside.

[0053] Comparative Example 4:

[0054] The difference from Example 1 is that 2 parts by weight of the surfactant (consisting of alkyl glycoside and 2,5-furandimethanol at a mass ratio of 1:2) in S1 is replaced by 2 parts by weight of 2,5-furandimethanol.

[0055] Comparative Example 5:

[0056] The difference from Example 1 is that the γ-alumina and the modified silicon dioxide are mixed uniformly at a ratio of 9:1 without plasma treatment.

[0057] The performance of a palladium type carbon monoxide combustion improver prepared in Example 1, Examples 2, 3, and Comparative Examples 1, 2, 3, 4, and 5 was tested.

[0058] 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; the abrasion index was tested according to the "Determination of Abrasion Index" GB / T6609.33-2009, as shown in Table 1.

[0059] Table 1: Performance test table of carbon monoxide combustion improver of palladium type

[0060]

[0061] As shown in Table 1, the active component content of the carbon monoxide combustion improver of the examples was between 0.052 and 0.058%, the specific surface area was between 190 and 202 m 2 / g, and the abrasion index was between 3.25 and 3.60%. The active component content and the specific surface area of the carbon monoxide combustion improver of the comparative examples were lower than those of the examples, and the abrasion index was higher than that of the examples.

[0062] During the preparation of the carbon monoxide combustion improver, the modification of the carrier can improve the adsorption capacity of the active component palladium metal. The mixing of alumina and modified silica can optimize the pore size distribution, specific surface area and other pore structures of the carrier. The γ-alumina can maintain structural stability under high temperature conditions and is not prone to phase change, which can effectively resist the destruction of the carrier structure by high temperature, reduce abrasion, and ensure that the performance of the combustion improver will not rapidly decay during long-term use. The addition of modified silica can significantly improve the mechanical strength and wear resistance of the carrier, reduce the abrasion and breakage of the combustion improver during the catalytic reaction process, and prolong the service life of the catalyst. 2,5-furan dimethyl alcohol can participate in the crosslinking of the modified carrier through hydroxyl condensation reaction during the calcination process, forming a more compact network structure and enhancing the mechanical strength such as wear resistance and impact resistance of the modified carrier. Alkyl glycoside promotes the uniform dispersion of the active component through surface activity, and 2,5-furan dimethyl alcohol anchors the dispersed active component firmly on the surface of the carrier through coordination and hydrogen bond action, and the combination of the two can significantly reduce the agglomeration of the active component and improve the specific surface area of the modified carrier. The high-energy particles in the plasma can activate the aluminum hydroxyl groups (Al-OH) on the surface of γ-alumina and the silicon hydroxyl groups (Si-OH) on the surface of modified silica, causing dehydration condensation reaction between the two at the interface to form Al-O-Si bonds and improve the overall mechanical strength of the modified carrier.

[0063] The palladium type carbon monoxide combustion improver prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5 was evaluated in a riser catalytic cracking simulation device. The catalyst was a balance agent for a petrochemical catalytic cracking device. 10 kg of the balance agent was weighed, 100 g of the palladium type carbon monoxide combustion improver prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5 was mixed with the 10 kg of the balance agent, and then was added to the regenerator of the riser catalytic cracking simulation device. The raw material was coking wax oil, the temperature was 525°C, the regenerator temperature was 660°C, the pressure was 0.15 MPa, the catalyst to oil ratio was 6.5, and the main air flow was 2500 NL / h. After the simulation device was normally operated, the flue gas was collected at 12 h for detection.

[0064] Table 2: Evaluation table of the palladium type carbon monoxide combustion improver

[0065]

[0066] As shown in Table 2, the carbon monoxide conversion rate of the palladium type carbon monoxide combustion improver prepared in the examples was between 96.4% and 98.6%, which was higher than that of the comparative examples. The carbon monoxide conversion rate of the palladium type carbon monoxide combustion improver prepared in Comparative Examples 1, 2, 3, 4, 5 was respectively 15.6%, 11.4%, 8.5%, 13.1% and 11.2% lower than that of Example 1. The increase in the nitrogen monoxide of the palladium type carbon monoxide combustion improver prepared in the examples was between 21 ppm and 25 ppm, which was lower than that of the comparative examples. The increase in the nitrogen monoxide of the palladium type carbon monoxide combustion improver prepared in Comparative Examples 1, 2, 3, 4, 5 was respectively 147.6%, 104.8%, 61.9%, 95.2% and 81.0% higher than that of Example 1.

[0067] The mixing of γ-alumina and modified silica can optimize the pore size distribution, specific surface area and other pore structures of the carrier, improve the mass transfer efficiency, reduce the diffusion resistance of the reactants, improve the reaction activity and catalytic efficiency, and thus improve the CO conversion rate and reduce the NO X content. γ-alumina has a high specific surface area, a small particle size and a rich void structure, which can provide sufficient attachment sites for the active component palladium of the combustion improver, increase the contact area between the active component palladium and carbon monoxide, and improve the efficiency of the combustion reaction. 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 in the reaction, but also can adjust the redox performance of the active component through the electronic effect, and enhance the catalytic oxidation ability of the active component to carbon monoxide. The surface of the silica modified by γ-aminopropyl triethoxysilane is positively charged, which can uniformly disperse the palladium particles through electrostatic repulsion, narrow the particle size distribution, and expose more palladium active sites, so as to improve the activity of the combustion improver, improve the CO conversion rate and reduce the NO Xcontent. 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.

[0068] 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.

[0069] 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 improver: Weigh 60 to 70 parts by weight of the modified support and 28 to 32 parts by weight of the active palladium metal precursor solution and place them in an ultrasonic device at a frequency of 90 to 100 Hz and a temperature of 45 to 50 ° C for 25 to 30 min to obtain a mixture; the mixture was spray-dried in a spray drying device and placed in a muffle furnace, and in a nitrogen atmosphere, the temperature was increased at a heating rate of 5 ° C / min to 450 to 500 ° C and maintained for 2.0 to 2.5 h to obtain a semi-finished combustion improver; the semi-finished combustion improver was placed in a reactor and reduced at 300 to 320 ° C for 1.5 to 2.0 h to obtain a finished combustion improver; 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.

2. 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.

3. 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℃.

4. 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.

5. The preparation method of 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.

6. 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.

7. The preparation method of the 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.

8. The preparation method of palladium type carbon monoxide combustion improver according to claim 1, wherein The γ-alumina Content>98%, Content <0.5%, <0.05%; the particle size of γ-alumina is 5-20 μm, and the specific surface area is 260-320 m 2 / g.

9. 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 8.

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