Monolithic catalytic oxidation catalyst, preparation method and application thereof, and VOCs catalytic oxidation method

Abstract

The invention relates to the field of catalyst preparation, and discloses a monolithic catalytic oxidation catalyst, a preparation method and application thereof, and a VOCs catalytic oxidation method. The invention relates to a preparation method of a monolithic catalytic oxidation catalyst, which comprises the following steps: (1) introducing coating slurry into a regular-structure support, and then carrying out first drying and optional first roasting to obtain a regular-structure support carrier loaded with a coating; (2) in an atmosphere containing water vapor, carrying out modification treatment on the regular-structure support carrier to obtain a modified regular-structure support carrier; and (3) impregnating the modified regular-structure supporting body carrier in an impregnation liquid containing a noble metal precursor, adjusting the pH value to be alkaline, standing, heating, and then carrying out second drying and second roasting. The preparation method improves the utilization rate of the noble metal active center, and the synthesized monolithic catalytic oxidation catalyst has wide application prospects in the fields of catalytic combustion, selective oxidation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a monolithic catalytic oxidation catalyst, a preparation method and application thereof, and a VOCs catalytic oxidation method. Background Art

[0002] In order to cope with high space velocity, honeycomb catalysts are commonly used for treating VOCs in industrial waste gas. One type of honeycomb catalyst has its active components directly formed by an extruder; another type uses a honeycomb carrier, such as honeycomb ceramics, and then a slurry containing powders with stronger loading capacity is coated thereon. The coating left after drying and calcination is used to load the active components. The formulation of the slurry plays a decisive role in the composition, loading amount, shedding rate and loading capacity of the coating. The active metals loaded on the limited specific surface area generally select noble metals with strong activity. Generally speaking, in order to improve the dispersion degree of active centers, the formulation of the slurry focuses on increasing the slurry loading amount, improving the pore structure of the powders, and increasing the specific surface area of the coating. However, there is a limit to the loading amount of the coating. Often, an excessive loading amount will lead to an increase in the shedding rate. There are great limitations in improving the dispersion degree of noble metals from the perspective of increasing the specific surface area.

[0003] Patent application CN112691542A discloses a preparation method of a metal composite molecular sieve material for adsorbing-catalytic oxidizing VOCs, which is characterized in that the molecular sieve is dissolved in water, and the metal precursor is impregnated or photodeposited on the molecular sieve to prepare a metal composite molecular sieve material for adsorbing-catalytic oxidizing VOCs. This method first deposits the active centers on the secondary carrier molecular sieve and then loads the molecular sieve onto the honeycomb ceramics in the form of a slurry. Although the dispersion degree of active centers such as noble metals is improved, at the same time, some active centers will be wrapped and covered during the second loading process and cannot effectively contact the reactants.

[0004] Patent application CN103191733A discloses a low-concentration methane combustion catalyst, which is characterized in that the catalyst comprises a carrier, an additive and an active component. The additive includes additive one and additive two; additive one is selected from one or a combination of noble metals Pt, Rh, Ru, Ir, and its content in terms of elemental metal is 0.1 wt% - 20 wt% of the total weight of the active component; additive two is selected from one or a combination of CeO2, ZrO2, La2O3, TiO2, and its content in terms of oxide is 1 wt% - 30 wt% of the total weight of the carrier. This catalyst uses additives to improve the hydrothermal stability of the catalyst, suppress the aggregation of active centers from the perspective of protecting the stability of the carrier, and help the active centers maintain dispersion. However, it is not very helpful for the dispersion of active centers during the synthesis stage, and only maintains rather than improves the effect of the catalyst. Summary of the Invention

[0005] The object of the present invention is to overcome the technical problems existing in the prior art, and to provide a monolithic catalytic oxidation catalyst, a preparation method and an application thereof, and a VOCs catalytic oxidation method. The preparation method improves the utilization rate of noble metal active centers, and the synthesized monolithic catalytic oxidation catalyst has broad application prospects in the fields of catalytic combustion, selective oxidation, etc.

[0006] To achieve the above object, the first aspect of the present invention provides a preparation method of a monolithic catalytic oxidation catalyst, wherein the method comprises the following steps:

[0007] (1) Introduce a coating slurry onto a structured support, and then perform a first drying and optionally a first calcination to obtain a structured support carrier loaded with a coating;

[0008] (2) Under an atmosphere containing water vapor, perform a modification treatment on the structured support carrier to obtain a modified structured support carrier;

[0009] (3) Immerse the modified structured support carrier in an impregnation solution containing a noble metal precursor, adjust the pH to alkaline, let it stand and then heat, and then perform a second drying and a second calcination.

[0010] The second aspect of the present invention provides a monolithic catalytic oxidation catalyst prepared by the preparation method described in the first aspect.

[0011] The third aspect of the present invention provides an application of the monolithic catalytic oxidation catalyst described in the second aspect in a catalytic oxidation reaction.

[0012] The fourth aspect of the present invention provides a VOCs catalytic oxidation method, wherein the method comprises subjecting an exhaust gas containing VOCs to a catalytic oxidation reaction with the monolithic catalytic oxidation catalyst described in the second aspect.

[0013] The preparation method provided by the present invention introduces a large number of -OOH groups onto the structured support carrier loaded with a coating through a modification treatment (thermal steam treatment), and then impregnates it with a noble metal precursor. The surface -OOH groups are used to reduce noble metal ions to the metallic state by the surface-assisted reduction (SAR) reaction and are loaded onto the carrier to achieve the effect of highly dispersing noble metals, thereby improving the catalytic activity of the catalytic oxidation reaction.

[0014] The preparation method provided by the present invention improves the utilization rate of noble metal active centers, and the synthesized catalyst has broad application prospects in the fields of catalytic combustion, selective oxidation, etc. Specific embodiments

[0015] The endpoints and any values disclosed in this text are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

[0016] The first aspect of the present invention provides a method for preparing an integral catalytic oxidation catalyst, wherein the method comprises the following steps:

[0017] (1) Introduce the coating slurry onto the structured support, and then perform the first drying and optionally the first calcination to obtain a structured support carrier loaded with the coating;

[0018] (2) Under an atmosphere containing water vapor, perform a modification treatment on the structured support carrier to obtain a modified structured support carrier;

[0019] (3) Immerse the modified structured support carrier in an impregnation solution containing a noble metal precursor, adjust the pH to alkaline, let it stand and then heat, and then perform the second drying and the second calcination.

[0020] The preparation method provided by the present invention introduces a large number of -OOH groups onto the structured support carrier loaded with the coating through the modification treatment (thermal steam treatment), and then impregnates it with a noble metal precursor. The surface -OOH groups are used to reduce the noble metal ions to the metallic state by the surface-assisted reduction (SAR) reaction and are loaded onto the carrier to achieve the effect of highly dispersing the noble metal, thereby improving the catalytic activity of the catalytic oxidation reaction.

[0021] The preparation method provided by the present invention improves the utilization rate of noble metal active centers, and the synthesized catalyst has broad application prospects in the fields of catalytic combustion, selective oxidation, etc.

[0022] The preparation method provided by the present invention modifies the coating of the structured support through an atmosphere containing water vapor to obtain a modified surface with a large number of -OOH groups. In an aqueous environment, the noble metal ions can be reduced from the ionic state to the metallic state and remain on the coating surface. This surface-assisted reduction (SAR) reaction helps the noble metal active centers to be highly dispersed on the surface of the coating carrier.

[0023] In the present invention, the type selection range of the regular structure support is relatively wide. The regular structure support can be a whole carrier block with a hollow pore structure formed inside. A coating containing alumina can be distributed on the inner wall of the pore, and the pore can be used as a flow space for the fluid. The matrix is selected from the regular structure supports selected from monolithic carriers with a parallel pore structure having two open ends; the regular structure support can be a honeycomb-type regular carrier (referred to as honeycomb ceramics for short) with a honeycomb-shaped opening in the cross section.

[0024] In the present invention, preferably, in step (1), the regular structure support is honeycomb ceramics.

[0025] In the present invention, preferably, in step (1), the regular structure support is selected from at least one of cordierite honeycomb carriers, mullite honeycomb carriers, diamond honeycomb carriers, corundum honeycomb carriers, zircon corundum honeycomb carriers, quartz honeycomb carriers, nepheline honeycomb carriers, feldspar honeycomb carriers, alumina honeycomb carriers, and metal alloy honeycomb carriers.

[0026] In the present invention, preferably, before step (1), the regular structure support is pretreated to achieve the purpose of making the slurry easier to adhere. The specific operations and conditions of the pretreatment can be carried out according to the conventional technical means in the art. Preferably, under ultrasonic conditions, an acid, particularly preferably nitric acid, is used for the pretreatment (the concentration of nitric acid is preferably 0.2 - 1 mol / L), and the ultrasonic oscillation treatment time is preferably 10 - 60 minutes. More preferably, washing and first drying are also included after the pretreatment. In the present invention, the washing can be carried out by the conventional technical means in the art, and the present invention has no particular limitation in this regard. In the present invention, the condition selection range for the first drying is relatively wide. Preferably, the conditions for the first drying include: the temperature is 100 - 150 °C, and the time is 12 - 24 hours.

[0027] In the present invention, there is no particular limitation on the specific method of introducing the coating slurry onto the regular structure support. For example, it can be coating or impregnation, preferably impregnation. In the present invention, the coating can be carried out once or multiple times as long as the required amount of coating can be obtained. In the present invention, preferably, in step (1), the impregnation time is 2 - 10 minutes.

[0028] In the present invention, the condition selection range for the first calcination is relatively wide. Preferably, the conditions for the first calcination include: the temperature is 400 - 500 °C, and the time is 2 - 4 hours.

[0029] In the present invention, there are no particular limitations on the types and contents of the components in the coating slurry. Preferably, the coating slurry contains alumina, a solvent, a surfactant, and an alumina precursor. Among them, based on the total amount of the coating slurry, the content of the solvent is 40 - 70 wt%, for example, it can be 40 wt%, 50 wt%, 60 wt%, 70 wt%, and the values between any two groups; the content of the alumina is 20 - 42 wt%, for example, it can be 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 42 wt%, and the values between any two groups; the content of the surfactant is 3 - 5 wt%, for example, it can be 3 wt%, 4 wt%, 5 wt%, and the values between any two groups; the content of the alumina precursor is 3 - 5 wt%, for example, it can be 3 wt%, 4 wt%, 5 wt%, and the values between any two groups.

[0030] In the present invention, the contents of the components in the coating slurry are calculated based on the feeding amounts.

[0031] In the present invention, the range of selection of the type of the solvent is relatively wide, as long as it can provide an environment for mixing other components in the slurry. Preferably, in step (1), the solvent is water and / or alcohol, and more preferably water and alcohol.

[0032] In the present invention, the range of selection of the type of the alcohol is relatively wide, and the low-carbon alcohols defined in the art can all be applicable to the present invention. Preferably, in step (1), the alcohol is an alcohol with 1 - 5 carbon atoms, and more preferably selected from at least one of ethanol, ethylene glycol, glycerol, and butanol.

[0033] In the present invention, there are no particular limitations on the amounts of the alcohol and water, as long as they can meet the requirements for mixing other components in the slurry. Preferably, in step (1), the mass ratio of the alcohol to the water is 1 - 2.5:20.

[0034] In the present invention, there are no particular limitations on the properties of the alumina. Preferably, in step (1), the specific surface area of the alumina is 100 - 1000 m 2 / g.

[0035] In the present invention, there are no particular limitations on the source of the alumina. For example, commercially available products can be used or it can be prepared according to the existing technology.

[0036] In the present invention, the range of selection of the type of the alumina precursor is relatively wide. Preferably, in step (1), the alumina precursor is selected from at least one of pseudoboehmite, aluminum hydroxide, and aluminum sec-butoxide, and more preferably pseudoboehmite. Even more preferably, the specific surface area of the pseudoboehmite is 150 - 380 m 2 / g.

[0037] In the present invention, there is no particular limitation on the source of the alumina precursor. For example, commercially available products can be used or it can be prepared according to the prior art.

[0038] In the present invention, the type of surfactant can be selected within a relatively wide range, as long as it can achieve the purpose of uniform dispersion of each component in the slurry. Preferably, in step (1), the surfactant is selected from at least one of polyethylene glycol, urea, sodium dodecylbenzenesulfonate, and stearic acid.

[0039] In the present invention, preferably, in step (1), the coating slurry further contains a transition metal, and the transition metal is selected from at least one of group IIIB metal elements, group IVB metal elements, and group VB metal elements. The group IIIB metal elements include, but are not limited to, Y and lanthanide metals. The group IVB metal elements include, but are not limited to, Ti and Zr. The group VB metal elements include, but are not limited to, V, Nb, and Ta.

[0040] In the present invention, preferably, the transition metal is selected from at least one of cerium, lanthanum, zirconium, titanium, and vanadium. Adding the transition metal within the above preferred range to the coating slurry can improve the stability of the coating slurry.

[0041] In the present invention, there is no particular limitation on the form of existence of the transition metal, as long as the transition metal can be introduced into the slurry coating. According to a preferred embodiment of the present invention, the transition metal exists in the coating slurry in the form of a transition metal salt. The advantage of adopting this preferred embodiment is that the feeding is simple.

[0042] In the present invention, there is no particular limitation on the content of the transition metal salt. Preferably, based on the total amount of the coating slurry, the content of the transition metal salt is 1-5 wt%.

[0043] According to another preferred embodiment of the present invention, the transition metal is loaded on alumina in the form of a transition metal salt or a transition metal oxide. The advantage of adopting this preferred embodiment is that local agglomeration is not likely to occur.

[0044] In the present invention, there is no particular limitation on the content of the transition metal salt or the transition metal oxide. Preferably, based on the total amount of the coating slurry, the content of the transition metal salt or the transition metal oxide is 1-5 wt%.

[0045] In the present invention, preferably, the pH value of the coating slurry is 3-4.

[0046] In the present invention, the pH value of the coating slurry can be adjusted by adding an acid or a base, and preferably an inorganic acid solution can be used. For example, it can be at least one of nitric acid, sulfuric acid, and hydrochloric acid.

[0047] In the present invention, there is no particular limitation on the amount of the inorganic acid solution, as long as the pH value of the coating slurry is 3 - 4, and those skilled in the art can select according to actual needs. In the present invention, the total amount of the amount of the inorganic acid solution and the contents of other components in the coating slurry meets 100%.

[0048] In the present invention, preferably, at 25°C, the viscosity of the coating slurry is 10 - 100 mPa·s.

[0049] In the present invention, the viscosity of the coating slurry refers to the viscosity measured by a viscometer at 25°C.

[0050] In the present invention, there is no particular limitation on the preparation method of the coating slurry. Preferably, the preparation method of the coating slurry includes the following steps: under stirring conditions, alumina, an alumina precursor, a surfactant, and a solvent are mixed uniformly, and then the pH is adjusted to 3 - 4 to obtain the coating slurry.

[0051] In the present invention, there is no particular limitation on the introduction order of each component in the coating slurry. For example, all components can be mixed and added together, or the transition metal, alumina, alumina precursor, and surfactant can be mixed first, and then the solvent is added. According to a specific embodiment of the present invention, the method includes the following steps: S1. Mix the transition metal, alumina, alumina precursor, and surfactant to obtain a mixed slurry; S2. Add the solvent to the mixed slurry obtained in step S1, and then add an acid-base regulator to adjust the pH to 3 - 4 to obtain the coating slurry. Preferably, step S1 and step S2 are each independently carried out under stirring conditions. Preferably, the stirring conditions include: the rotation speed is 2000 - 12000 revolutions per minute, and the time is 4 - 12 hours. Here, the stirring time refers to the total stirring time of step S1 and step S2.

[0052] In the present invention, there is no particular limitation on the type of the atmosphere containing water vapor, as long as it can provide steam conditions. Preferably, in step (2), the atmosphere containing water vapor includes water vapor and optionally the vapor of C1 - C4 alcohols and optionally the vapor of C1 - C4 organic acids. The advantage of adopting this preferred embodiment is that the alcohols and acids with lower carbon numbers have stronger polarity and better hydroxylation effect.

[0053] In the present invention, preferably, in step (2), the C1 - C4 alcohol is selected from at least one of methanol, ethanol, ethylene glycol, glycerol, and butanol, and more preferably at least one of ethanol, ethylene glycol, and methanol.

[0054] In the present invention, preferably, in step (2), the C1 - C4 organic acid is selected from at least one of formic acid, acetic acid, propionic acid, and butyric acid, and more preferably formic acid and / or acetic acid.

[0055] In the present invention, there is no particular limitation on the content of each atmosphere in the atmosphere containing water vapor. Preferably, in step (2), based on the total volume of the atmosphere containing water vapor, the content of water vapor in the atmosphere containing water vapor is 60-100% by volume, for example, it can be 60% by volume, 65% by volume, 70% by volume, 75% by volume, 80% by volume, 85% by volume, 90% by volume, 95% by volume, 100% by volume, and the values between any two groups. The content of the vapor of C1-C4 alcohols is 0-20% by volume, for example, it can be 0% by volume, 5% by volume, 10% by volume, 15% by volume, 20% by volume, and the values between any two groups. The content of the vapor of C1-C4 organic acids is 0-20% by volume, for example, it can be 0% by volume, 5% by volume, 10% by volume, 15% by volume, 20% by volume, and the values between any two groups.

[0056] In the present invention, there is no particular limitation on the conditions of the modification treatment. Preferably, in step (2), the conditions of the modification treatment include: the temperature is 50-400 °C, the time is 4-30 hours, and the volume space velocity of the atmosphere containing water vapor is 500-5000 h -1 ; More preferably, in step (2), the conditions of the modification treatment include: the temperature is 120-180 °C, the time is 6-24 hours, and the volume space velocity of the atmosphere containing water vapor is 800-2000 h -1 .

[0057] In the present invention, the selection range of the types of noble metals is relatively wide. Preferably, in step (3), the noble metal is selected from at least one of platinum, palladium, rubidium, and rhodium, and more preferably platinum and palladium. The present invention has a relatively wide selection range for the ratio of platinum and palladium, for example, it can be 1:0.1-10.

[0058] In the present invention, preferably, in step (3), the impregnating solution containing the noble metal precursor is provided by a salt solution of the noble metal, preferably provided by a nitrate solution and / or a chlorate solution.

[0059] In the present invention, there is no particular limitation on the concentration of the impregnating solution containing the noble metal precursor. Preferably, in step (3), the concentration of the impregnating solution containing the noble metal precursor is 0.1-4 g / L.

[0060] In the present invention, preferably, in step (3), the conditions of the static standing include: the time is 1-6 hours.

[0061] In the present invention, preferably, in step (3), the conditions of the heating include: the temperature is 50-80 °C, the time is 1-6 hours.

[0062] In the present invention, ammonia water can be used to adjust the pH to alkaline, and preferably the pH is adjusted to 8-9. Preferably, the concentration of the ammonia water is 0.5-1 mol / L.

[0063] In the present invention, the conditions for the second drying have a relatively wide selection range. Preferably, in step (3), the conditions for the second drying include: the temperature is 100-150 °C and the time is 12-24 hours.

[0064] In the present invention, the conditions for the second calcination have a relatively wide selection range. Preferably, in step (3), the conditions for the second calcination include: the calcination temperature is 400-500 °C and the time is 2-4 hours.

[0065] In the present invention, preferably, the amounts of the structured support and the coating slurry are such that in the structured support carrier loaded with the coating, based on the total amount of the structured support carrier loaded with the coating, the content of the structured support is 88-95 wt%, for example, it can be 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt% and the values between any two groups, and the content of the coating is 5-12 wt%, for example, it can be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt% and the values between any two groups.

[0066] In the present invention, in the structured support carrier loaded with the coating, the content of the structured support and the content of the coating can be obtained by testing through conventional technical means in the art. For example, it can be obtained by weighing the materials before and after coating, or the weight can be determined according to the shape and manufacturer of the structured support, and then the percentage content of the structured support can be calculated.

[0067] In the present invention, preferably, based on the total amount of the coating, in the coating, the content of the alumina is 90-97 wt%, and the content of the transition metal in terms of oxide is 3-10 wt%.

[0068] In the present invention, the contents of the components in the coating are measured by ICP testing.

[0069] In the present invention, preferably, the amount of the impregnating solution containing the noble metal precursor is such that in the monolithic catalytic oxidation catalyst prepared, based on the total volume of the monolithic catalytic oxidation catalyst, the content of the noble metal in terms of element is 0.1-4 g / L, for example, it can be 0.1 g / L, 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L and the values between any two groups.

[0070] In the present invention, the noble metal content in the monolithic catalytic oxidation catalyst is measured by ICP test.

[0071] The second aspect of the present invention provides a monolithic catalytic oxidation catalyst prepared by the preparation method described in the first aspect.

[0072] The third aspect of the present invention provides an application of the monolithic catalytic oxidation catalyst described in the second aspect in a catalytic oxidation reaction.

[0073] The fourth aspect of the present invention provides a method for catalytic oxidation of VOCs. Among them, the method includes subjecting the waste gas containing VOCs to a catalytic oxidation reaction with the monolithic catalytic oxidation catalyst described in the second aspect.

[0074] In the present invention, preferably, the conditions of the catalytic oxidation reaction include: the reaction pressure is atmospheric pressure, the reaction temperature is 200 - 600 °C, and the volume space velocity of the waste gas containing VOCs is 5000 - 60000 h -1 .

[0075] In the present invention, preferably, in the waste gas containing VOCs, the concentration of VOCs is 500 - 10000 ppm.

[0076] The present invention has a wide selection range for the types of VOCs substances, and can be one or several substances such as alkanes, alkenes, benzene series, oxygen-containing VOCs, and chlorine-containing VOCs.

[0077] The monolithic catalyst provided by the present invention is suitable for the treatment of various industrial waste gases, and is particularly suitable for the treatment of waste gases containing VOCs substances in the oil refining and chemical industries.

[0078] The present invention will be described in detail below through examples. Unless otherwise specified, the raw materials used in the following examples are all commercially available products.

[0079] The pseudo-boehmite used in the following examples and comparative examples is SB powder, with a specific surface area of 350 m 2 / g. The alumina powder is obtained by calcining SB powder at 540 °C, and has a specific surface area of 300 m 2 / g. The honeycomb ceramic is a 400-mesh cordierite honeycomb ceramic.

[0080] The noble metal content is measured by ICP test.

[0081] The specific surface area of the sample was measured by a physical adsorption instrument, and an AUTO-SORB-1-MP analyzer from Quantachrome Corporation, USA was used. Operating conditions: Before testing, the sample was vacuum degassed at 300 °C for 6 hours on an external degassing station. Subsequently, nitrogen was used as the adsorbate, and the adsorption and desorption tests were carried out at the liquid ammonia temperature (77 K). The specific surface area of the sample was calculated by the Brunauer-Emmett-Teller (BET) method.

[0082] The average particle diameter of the noble metal component was observed by STEM for the sample morphology and particle size distribution to statistically analyze the particle size. A JEM-F200 field emission transmission electron microscope from JEOL Ltd., Japan was used. Operating conditions: The acceleration voltage was 200 kV. Before testing, a small amount of powder sample was ultrasonically dispersed in absolute ethanol and dropped onto a copper grid with a capillary, and then dried before testing.

[0083] Example 1

[0084] (1) Dissolve 10 g of cerium nitrate in 160 g of water;

[0085] (2) Mix the cerium nitrate salt solution obtained in step (1) with alumina powder, urea, and pseudo-boehmite in a mass ratio of 170:90:10:10 and stir vigorously at a rotation speed of 10,000 revolutions per minute for 6 hours to obtain a mixed slurry;

[0086] (3) Add 18 g of butanol to the mixed slurry obtained in step (2), then stir vigorously at a rotation speed of 10,000 revolutions per minute for 1 hour; adjust the pH value to 3.5 by adding concentrated nitric acid, and then stir at a rotation speed of 10,000 revolutions per minute for 1 hour to obtain the coating slurry.

[0087] (4) Place 100 mL of honeycomb ceramics into 200 mL of 1 mol / L nitric acid solution and shake in an ultrasonic oscillator for 1 hour; then rinse repeatedly with 500 mL of clear water, and then dry in an oven at 110 °C for 12 hours;

[0088] (5) Immerse the honeycomb ceramics in step (4) in the coating slurry in step (3) for 5 minutes. After taking out, blow out the residual coating slurry from the pores. The supported honeycomb ceramics are dried in an oven at 110 °C for 12 hours, and then calcined in a muffle furnace at 500 °C for 2 hours to obtain a monolithic honeycomb ceramic catalyst support. The monolithic honeycomb ceramic catalyst support contains honeycomb ceramics and a coating. Based on the total amount of the coating, in the coating, the content of the alumina is 94 wt%, and the content of the transition metal in terms of oxide is 6 wt%;

[0089] (6) Transfer the monolithic honeycomb ceramic catalyst support in step (5) to a tubular furnace and treat it with steam at 180 °C for 24 hours. The volumetric space velocity of the steam is 1000 h -1 , and obtain a hydrothermally modified monolithic honeycomb ceramic catalyst support;

[0090] (7) Prepare 150 mL of a nitrate solution of palladium and platinum with a concentration of 1 g / L for palladium and 0.5 g / L for platinum;

[0091] (8) Immerse the hydrothermally modified monolithic honeycomb ceramic catalyst support obtained in step (6) in the solution in step (7), add concentrated ammonia water to adjust the pH to 8 - 9, then let it stand for 4 hours, and then heat the solution to 70 °C and maintain it for 1 hour;

[0092] (9) After taking out the honeycomb ceramic catalyst, purge it with dry air for 2 hours, then dry it in an oven at 110 °C for 12 hours, and then calcine it in a muffle furnace at 450 °C for 4 hours to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM - 1.

[0093] Based on the total amount of the monolithic honeycomb ceramic catalyst support, the content of the honeycomb ceramic is 91.9 wt%, and the content of the coating is 8.1 wt%.

[0094] Example 2

[0095] Steps (1) - (5) are the same as in Example 1.

[0096] (6) Transfer the monolithic honeycomb ceramic catalyst support in step (5) to a tubular furnace and use a mixed steam of water and ethanol, where water accounts for 80% by volume and ethanol accounts for 20% by volume. The volumetric space velocity of the mixed steam of water and ethanol is 1000 h -1 , and treat it at 170 °C for 12 hours to obtain a hydrothermally modified monolithic honeycomb ceramic catalyst support;

[0097] (7) Prepare 150 mL of a nitrate solution of palladium and platinum with a concentration of 0.5 g / L for palladium and 1 g / L for platinum;

[0098] (8) Immerse the hydrothermally modified monolithic honeycomb ceramic catalyst obtained in step (6) in the solution in step (7), add concentrated ammonia water to adjust the pH to 8 - 9, and then let it stand for 6 hours;

[0099] (9) After taking out the honeycomb ceramic catalyst, purge it with dry air for 2 hours, then dry it in an oven at 110 °C for 12 hours, and then calcine it in a muffle furnace at 500 °C for 2 hours to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM - 2.

[0100] Based on the total amount of the monolithic honeycomb ceramic catalyst support, the content of the honeycomb ceramic is 92 wt%, and the content of the coating is 8 wt%.

[0101] Example 3

[0102] Steps (1)-(5) are the same as in Example 1.

[0103] (6) Transfer the monolithic honeycomb ceramic catalyst support obtained in step (5) to a tubular furnace, and use a mixed vapor of water, ethanol, and formic acid at a concentration of 100 ml / L, where water accounts for 70% by volume, ethanol accounts for 20% by volume, and formic acid accounts for 10% by volume. The volume space velocity of the mixed vapor of water, ethanol, and formic acid is 800 h -1 , and treat it at 120 °C for 8 hours to obtain a hydrothermally modified monolithic honeycomb ceramic catalyst support;

[0104] (7) Prepare 150 mL of a nitrate solution of palladium and platinum with a concentration of 0.75 g / L for palladium and 0.75 g / L for platinum;

[0105] (8) Immerse the hydrothermally modified monolithic honeycomb ceramic catalyst support obtained in step (6) in the solution in step (7), add concentrated ammonia water to adjust the pH to 8-9, then let it stand for 6 hours, and then heat the solution to 70 °C and maintain it for 2 h;

[0106] (9) After taking out the honeycomb ceramic catalyst, blow it with dry air for 2 hours, then dry it in an oven at 110 °C for 12 hours, and then calcine it in a muffle furnace at 400 °C for 2 hours to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM-3.

[0107] Based on the total amount of the monolithic honeycomb ceramic catalyst support, the content of the honeycomb ceramic is 92 wt%, and the content of the coating is 8 wt%.

[0108] Example 4

[0109] According to the method of Example 3, the difference is that in step (6), the steam treatment temperature is 50 °C to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM-4.

[0110] Example 5

[0111] According to the method of Example 3, the difference is that step (1) is not carried out. Based on the total amount of the coating, in the coating, the content of the alumina is 100 wt%; to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM-5.

[0112] Example 6

[0113] According to the method of Example 3, except that in step (6), the steam treatment conditions are: temperature 400 °C, hold for 12 hours, to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM-6.

[0114] Example 7

[0115] According to the method of Example 3, except that

[0116] (1) Dissolve 8 g of lanthanum nitrate in 162 g of water;

[0117] (2) Mix the lanthanum nitrate solution obtained in step (1) with alumina powder, urea, and pseudoboehmite in a mass ratio of 170:90:8:12 and stir vigorously at a rotation speed of 8000 revolutions per minute for 6 hours to obtain a mixed slurry;

[0118] (3) Add 15 g of butanol to the mixed slurry obtained in step (2), then stir vigorously at a rotation speed of 10000 revolutions per minute for 1 hour, add concentrated nitric acid to adjust the pH value to 3.6, and then stir at a rotation speed of 10000 revolutions per minute for 1 hour to obtain a coating slurry;

[0119] To obtain the monolithic honeycomb ceramic catalytic oxidation catalyst STM-7.

[0120] Based on the total amount of the monolithic honeycomb ceramic catalyst support, the content of the honeycomb ceramic is 90.9 wt%, and the content of the coating is 9.1 wt%.

[0121] Comparative Example 1

[0122] According to the method of Example 3, except that the steam modification process in step (6) is not carried out, to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst DSTM-1.

[0123] Comparative Example 2

[0124] According to the method of Example 3, except that in step (6), formic acid vapor is used to replace the mixed vapor of water, ethanol, and formic acid in Example 3, and the volume space velocity of the formic acid vapor is 5000 h -1 , to obtain the monolithic honeycomb ceramic catalytic oxidation catalyst DSTM-2.

[0125] The parameters of the monolithic honeycomb ceramic catalytic oxidation catalysts prepared in the above examples and comparative examples are shown in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] In Table 1, the noble metal content is based on the total volume of the monolithic honeycomb ceramic catalytic oxidation catalyst.

[0130] Test Example

[0131] The monolithic honeycomb ceramic catalytic oxidation catalysts prepared in the examples and comparative examples were applied to the ethane catalytic oxidation reaction, and the reaction was carried out in a fixed-bed reactor of a medium-scale reaction evaluation device. The filling amount of the monolithic catalyst was 100 mL, the bed height was 10 cm, the initial concentration of ethane was 2000 ppm, the carrier gas was air, and the volume space velocity was 20000 h -1 . The ethane concentration was measured by an Agilent 7890A gas chromatograph, and the test results are shown in Table 2. Under the same conditions, benzene was used as the reactant, and the initial concentration of benzene was 3000 ppm. The test results are shown in Table 3.

[0132] Table 2

[0133] Catalyst Temperature for 50% ethane conversion Temperature for 70% ethane conversion Temperature for 90% ethane conversion Example 1 STM-1 379℃ 399℃ 415℃ Example 2 STM-2 375℃ 394℃ 410℃ Example 3 STM-3 380℃ 399℃ 414℃ Example 4 STM-4 402℃ 411℃ 435℃ Example 5 STM-5 395℃ 405℃ 428℃ Example 6 STM-6 409℃ 420℃ 440℃ Example 7 STM-7 385℃ 404℃ 420℃ Comparative Example 1 DSTM-1 428℃ 446℃ 475℃ Comparative Example 2 DSTM-2 432℃ 450℃ 480℃

[0134] Table 3

[0135]

[0136]

[0137] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing an integral catalytic oxidation catalyst, wherein, The method includes the following steps: (1) Introduce the coating slurry onto the structured support, and then perform first drying and optionally first calcination to obtain a structured support carrier loaded with the coating; (2) Under an atmosphere containing water vapor, perform a modification treatment on the structured support carrier to obtain a modified structured support carrier; (3) Immerse the modified structured support carrier in an impregnation solution containing a noble metal precursor, adjust the pH to alkaline, let it stand and then heat, and then perform second drying and second calcination.

2. The method according to claim 1, wherein, In step (1), the structured support is selected from monolithic carriers having a parallel pore structure with both ends open; Preferably, in step (1), the structured support is a honeycomb ceramic; Preferably, in step (1), the structured support is selected from at least one of cordierite honeycomb carriers, mullite honeycomb carriers, diamond honeycomb carriers, corundum honeycomb carriers, zircon corundum honeycomb carriers, quartz honeycomb carriers, nepheline honeycomb carriers, feldspar honeycomb carriers, alumina honeycomb carriers, and metal alloy honeycomb carriers.

3. The method according to claim 1 or 2, wherein, In step (1), the coating slurry contains alumina, a solvent, a surfactant, and an alumina precursor. Among them, based on the total amount of the coating slurry, the content of the solvent is 40-70 wt%, the content of the alumina is 20-42 wt%, the content of the surfactant is 3-5 wt%, and the content of the alumina precursor is 3-5 wt%.

4. The method according to claim 3, wherein, In step (1), the solvent is water and / or an alcohol; Preferably, in step (1), the alcohol is an alcohol having 1-5 carbon atoms, and more preferably is selected from at least one of ethanol, ethylene glycol, glycerol, and butanol; Preferably, in step (1), the mass ratio of the alcohol to the water is 1-2.5:20; Preferably, in step (1), the specific surface area of the alumina is 100-1000 m 2 / g; Preferably, in step (1), the alumina precursor is selected from at least one of pseudoboehmite, aluminum hydroxide, and aluminum sec-butoxide, and more preferably is pseudoboehmite; Preferably, in step (1), the specific surface area of the pseudo-boehmite is 150 - 380 m 2 / g; Preferably, in step (1), the surfactant is selected from at least one of polyethylene glycol, urea, sodium dodecylbenzenesulfonate, and stearic acid.

5. The method according to claim 3, wherein, In step (1), the coating slurry further contains a transition metal, and the transition metal is selected from at least one of group IIIB metal elements, group IVB metal elements, and group VB metal elements, and is preferably selected from at least one of cerium, lanthanum, zirconium, titanium, and vanadium; Preferably, the transition metal exists in the coating slurry in the form of a transition metal salt, and based on the total amount of the coating slurry, the content of the transition metal salt is 1-5 wt%; and / or, the transition metal is loaded on the alumina in the form of a transition metal salt or a transition metal oxide, and based on the total amount of the coating slurry, the content of the transition metal salt or the transition metal oxide is 1-5 wt%.

6. The method according to claim 1 or 2, wherein, In step (2), the atmosphere containing water vapor includes water vapor and optionally the vapor of an alcohol having 1-4 carbon atoms, and optionally the vapor of an organic acid having 1-4 carbon atoms; Preferably, in step (2), the alcohol having 1-4 carbon atoms is selected from at least one of methanol, ethanol, ethylene glycol, glycerol, and butanol; Preferably, in step (2), the C1-C4 organic acid is selected from at least one of formic acid, acetic acid, propionic acid, and butyric acid; Preferably, in step (2), based on the total volume of the water vapor-containing atmosphere, in the water vapor-containing atmosphere, the content of the water vapor is 60-100% by volume, the content of the vapor of the C1-C4 alcohol is 0-20% by volume, and the content of the vapor of the C1-C4 organic acid is 0-20% by volume.

7. The method according to claim 1 or 2, wherein, In step (2), the conditions for the modification treatment include: the temperature is 50 - 400 °C, the time is 4 - 30 hours, and the volumetric space velocity of the water vapor-containing atmosphere is 500 - 5000 h -1 ; Preferably, in step (2), the conditions for the modification treatment include: the temperature is 120-180°C, the time is 6-24 hours, and the volumetric space velocity of the water vapor-containing atmosphere is 800-2000 h -1 .

8. The method according to claim 1 or 2, wherein, In step (3), the noble metal is selected from at least one of platinum, palladium, rubidium, and rhodium; Preferably, in step (3), the impregnating solution containing the noble metal precursor is provided by a salt solution of the noble metal; Preferably, in step (3), the concentration of the impregnating solution containing the noble metal precursor is 0.1-4 g / L; Preferably, in step (3), the conditions for standing still include: the time is 1-6 hours; Preferably, in step (3), the conditions for heating include: the temperature is 50-80 °C and the time is 1-6 hours; Preferably, in step (3), the conditions for the second calcination include: the calcination temperature is 400-500 °C and the time is 2-4 hours.

9. The method according to claim 1 or 2, wherein, The amounts of the structured support and the coating slurry are such that in the prepared structured support carrier loaded with the coating, based on the total amount of the structured support carrier loaded with the coating, the content of the structured support is 88-95 wt%, and the content of the coating is 5-12 wt%; Preferably, the amount of the impregnating solution containing the noble metal precursor is such that in the prepared monolithic catalytic oxidation catalyst, based on the total volume of the monolithic catalytic oxidation catalyst, the content of the noble metal in terms of elements is 0.1-4 g / L.

10. The monolithic catalytic oxidation catalyst prepared by the preparation method according to any one of claims 1-9.

11. The application of the monolithic catalytic oxidation catalyst according to claim 10 in a catalytic oxidation reaction.

12. A method for catalytic oxidation of VOCs, wherein The method includes subjecting the waste gas containing VOCs to a catalytic oxidation reaction with the monolithic catalytic oxidation catalyst described in claim 10.

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