Monolithic catalysts, their preparation and use, and methods for catalytic combustion of organic waste gases containing cyclohexane

Abstract

The present application relates to the field of catalysts, and discloses a monolithic catalyst for catalytic combustion of organic waste gas containing cyclohexane, a preparation method and application thereof, and a method for catalytic combustion of organic waste gas containing cyclohexane.The catalyst comprises a carrier and an active component; wherein the carrier comprises a honeycomb ceramic containing a TS-1 molecular sieve coating; and the active component comprises a noble metal and ytterbium oxide.The catalyst of the present application can be used for catalytic combustion of organic waste gas containing cyclohexane, and can catalytically combust volatile organic compounds such as cyclohexane into carbon dioxide and water, and has high stability and catalyst activity.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to an integral catalyst for the catalytic combustion of cyclohexane-containing organic waste gas, its preparation method and application, and a method for the catalytic combustion of cyclohexane-containing organic waste gas. Background Technology

[0002] Environmental pollution is one of the most intractable problems facing the world, closely related to human production and daily life, with increasingly severe air pollution receiving widespread attention. Volatile organic compounds (VOCs) are a major source of air pollution. The most fundamental and effective way to control VOC pollution is to replace current processes with green and pollution-free technologies, reducing or eliminating the use of harmful raw materials and controlling waste gas emissions. However, due to limitations in scientific and technological levels, many industries affecting people's livelihoods have not yet found green and environmentally friendly alternatives, and their production and use inevitably still release various organic waste gases into the environment. For example, the use of chemical products such as paints, lubricants, and organic solvents; the synthesis of bulk chemicals; the incineration of industrial waste; petrochemicals and oil refining; rubber production; and the frequent use of pesticides all lead to large amounts of VOC emissions. Most VOCs have unpleasant odors, can cause illness and even cancer in humans, and their release into the air causes great damage to human health and the Earth's environment. Therefore, the effective treatment of organic waste gases generated during petrochemical industrial production is an important topic in environmental science.

[0003] Besides advocating and developing green and atom-economical methods and processes, post-treatment remains the most feasible and implementable solution for eliminating pollution. Common post-treatment methods can be divided into two main categories: non-destructive technologies, i.e., recycling methods, and destructive technologies, i.e., chemical methods. The former includes common methods such as activated carbon adsorption, solution absorption, condensation, and membrane separation. These methods generally achieve enrichment and separation by changing physical conditions such as pressure and temperature during the process. The latter mainly includes methods such as biodegradation, catalytic combustion, direct combustion, plasma oxidation, and photocatalytic oxidation. These methods primarily use chemical or biological technologies to convert volatile organic compounds (VOCs) into non-toxic or low-toxic inorganic substances such as carbon dioxide and water. Physical methods have the advantage of recycling VOCs, but the treatment is incomplete and can easily cause secondary pollution. Chemical methods are characterized by thorough treatment, with direct thermal combustion and catalytic combustion being the most widely used methods. Thermal combustion decomposes harmful substances in exhaust gases at high temperatures, reaching 800–900°C. This method consumes large amounts of fuel oil, resulting in high operating costs, high energy consumption, and high treatment costs. Catalytic combustion, on the other hand, utilizes a catalyst to lower the operating temperature to 280–450°C, significantly reducing energy consumption. It is safer, more stable, and less expensive, and it does not produce nitrogen oxides, thus avoiding secondary pollution. Therefore, catalytic combustion is a more ideal method for treating petrochemical organic waste gas.

[0004] Catalytic combustion catalysts are mainly classified into noble metal catalysts and non-noble metal catalysts. Compared with non-noble metal catalysts, noble metal catalysts generally have the characteristics of high activity and good stability. However, due to the rarity and high cost of noble metals, they are usually loaded onto a support when preparing noble metal catalysts. Commonly used supports are alumina supports or transition metal supports. The usual practice for preparing catalytic combustion catalysts is to coat alumina or transition metal oxides onto a honeycomb support, and then load the noble metal onto the honeycomb support coated with alumina or transition metal oxides.

[0005] CN102441379A and CN1415410A involve loading noble metals onto a honeycomb support coated with alumina or transition metal oxides. Because alumina and transition metal oxides have low specific surface areas, this results in lower catalyst activity. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low activity and poor stability of existing monolithic catalysts, and to provide a monolithic catalyst for catalytic combustion of cyclohexane-containing organic waste gas, which has better stability.

[0007] To achieve the above objectives, the first aspect of the present invention provides an integral catalyst for catalytic combustion of cyclohexane-containing organic waste gas, the catalyst comprising a support and an active component; wherein the support comprises a honeycomb ceramic coated with a TS-1 molecular sieve; and the active component comprises a noble metal and ytterbium oxide.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned monolithic catalyst, the method comprising:

[0009] (1) The raw material providing the TS-1 molecular sieve coating is coated onto the honeycomb ceramic, followed by a first drying and a first calcination to obtain the carrier;

[0010] (2) The carrier is contacted with a precursor solution containing precious metals and ytterbium, followed by separation, second drying, second calcination, and reduction.

[0011] A third aspect of the present invention provides the application of the above-mentioned catalyst in the catalytic combustion of cyclohexane-containing organic waste gas.

[0012] The fourth aspect of the present invention provides a method for catalytic combustion of cyclohexane-containing organic waste gas, the method comprising: introducing oxygen-containing gas and contacting the above-mentioned catalyst with the cyclohexane-containing organic waste gas at a temperature of 200-450°C.

[0013] The catalyst of this invention can be used to treat cyclohexane-containing organic waste gas, catalytically burning cyclohexane and other volatile organic compounds to produce carbon dioxide and water. The catalyst has high activity, even at a cyclohexane concentration of 8000 mg / m³. 3 Under certain conditions, when the catalyst bed temperature is not higher than 350℃, the conversion rate of cyclohexane is above 99%, and the selectivity of the final product carbon dioxide is above 99%. This catalyst can be widely used in the catalytic combustion reaction of industrial organic waste gases such as petrochemical organic waste gas containing cyclohexane. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] The first aspect of the present invention provides an integral catalyst for catalytic combustion of cyclohexane-containing organic waste gas, the catalyst comprising a support and an active component; wherein the support comprises a honeycomb ceramic coated with TS-1 molecular sieve; and the active component comprises a noble metal and ytterbium oxide.

[0016] In this invention, honeycomb ceramics, as a type of support, exhibit good thermal stability and dispersibility, but their surface area is relatively low. As mentioned earlier, existing technologies often use alumina or transition metal oxides coated on honeycomb ceramics. However, due to the low specific surface area of ​​alumina and transition metal oxides, the catalyst activity is low, and the difference in their expansion coefficients is significant. During the combustion treatment of organic waste gas, the continuous temperature changes can cause the coating to peel off, shortening the catalyst's lifespan, i.e., the catalyst's stability is poor. In this invention, the inventors use a specific honeycomb ceramic coated with a TS-1 molecular sieve as a support. The noble metals and ytterbium loaded on the support synergistically enhance both the catalyst's activity and stability.

[0017] According to the present invention, in some preferred embodiments, the content of the TS-1 molecular sieve coating is 3-25 wt% (e.g., 3 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, 14 wt%, 15 wt%, 20 wt%, 23 wt%, or 25 wt%), preferably 6-14 wt%, based on the mass of the honeycomb ceramic. Using the aforementioned embodiments, the overall activity of the catalyst can be further increased.

[0018] According to the present invention, the honeycomb ceramic can be any type of honeycomb ceramic, including but not limited to cordierite honeycomb ceramic, aluminum titanate honeycomb ceramic and mullite honeycomb ceramic. Cordierite honeycomb ceramic is used as an example to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0019] In this invention, it is understood that TS-1 molecular sieve is a titanium-silicon molecular sieve, and the coating of TS-1 molecular sieve contains titanium, that is, the catalyst also contains titanium. In some embodiments, the titanium content in the catalyst is 0.1-5 g / L based on the carrier volume and the amount of titanium, preferably 0.3-2.6 g / L (e.g., 0.3 g / L, 0.75 g / L, 1 g / L, 1.2 g / L, 1.5 g / L, 1.8 g / L, 2.3 g / L, 2.6 g / L, 4 g / L or 5 g / L), and more preferably 1-2.6 g / L. Under the aforementioned embodiments, the overall activity and stability of the catalyst can be further increased. The inventors speculate that the TS-1 molecular sieve coating can not only better adsorb noble metals and ytterbium, but also interact with noble metals and ytterbium to increase the activation ability of bonds such as O2, CH and OH. In addition, the interaction between the structure of the TS-1 molecular sieve coating and noble metals and ytterbium can prevent active components such as noble metals and ytterbium from being exposed to poisons, thereby enhancing the stability of the catalyst.

[0020] According to the present invention, it is understood that in some embodiments, the raw material for providing the TS-1 molecular sieve coating includes a coating liquid containing TS-1 molecular sieve. That is, the honeycomb ceramic with the TS-1 molecular sieve coating is formed by coating the honeycomb ceramic with a coating liquid containing TS-1 molecular sieve.

[0021] According to the present invention, as long as the purpose of the present invention can be achieved, the composition of the coating liquid containing TS-1 molecular sieve is not particularly limited. In some embodiments, the coating liquid includes TS-1 molecular sieve, pore-forming agent, viscosity modifier and water. By adopting the foregoing embodiments, a TS-1 molecular sieve coating with excellent coating performance can be obtained, which increases the activity and stability of the catalyst.

[0022] According to some embodiments of the present invention, the mass ratio of TS-1 molecular sieve to water is (0.05-0.8):1.

[0023] According to some embodiments of the present invention, the mass ratio of TS-1 molecular sieve to pore-forming agent is 1:(0.1-0.5).

[0024] According to some embodiments of the present invention, the mass ratio of TS-1 molecular sieve to viscosity modifier is 1:(0.02-0.18).

[0025] According to the present invention, in some embodiments, the pore-forming agent is selected from one or more of polyvinyl alcohol, carboxymethyl cellulose, hexadecyltrimethylammonium bromide, polyethylene glycol, P123 polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and poloxamer. Under the action of the aforementioned pore-forming agent, a highly active and stable catalyst can be obtained.

[0026] According to the present invention, in order to form the TS-1 molecular sieve coating, in some embodiments, the viscosity modifier is selected from one or more of nitric acid, acetic acid, boric acid, oxalic acid, and phosphoric acid, preferably nitric acid. Using the aforementioned embodiments, the catalyst exhibits higher activity and stability.

[0027] According to the present invention, noble metals possess catalytic oxidation activity. The specific type of noble metal is not particularly limited as long as the objective of the present invention is achieved. In some embodiments, the noble metal is selected from one or more of platinum, rhodium, palladium, gold, and silver, preferably platinum and palladium. Using the aforementioned embodiments can further increase the activity and stability of the catalyst.

[0028] According to the present invention, the specific content of platinum and palladium in the catalyst is not limited as long as the purpose of the present invention can be achieved. In some embodiments, the molar ratio of platinum to palladium in the catalyst is (0.015-2):1, preferably (0.1-0.5):1, based on elemental platinum and palladium. The aforementioned embodiments can increase the synergistic effect between platinum, palladium, the molecular sieve coating, and the support in the catalyst, thereby enhancing the activation of CH and CO bonds in cyclohexane-containing organic waste gas and further increasing the catalyst activity.

[0029] According to the present invention, in some embodiments, the palladium content in the catalyst, based on the support volume and palladium element content, is greater than 100 mg / L, preferably 120-1600 mg / L, and more preferably 120-400 mg / L. Using the aforementioned embodiments can increase the activity and stability of the catalyst.

[0030] According to the present invention, in some embodiments, the ytterbium content in the catalyst is 0.2-2 g / L, preferably 0.3-1.8 g / L, based on the volume of the support and the elemental content of ytterbium. Using the aforementioned embodiments can increase the activity and stability of the catalyst.

[0031] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, the method comprising:

[0032] (1) The raw material providing the TS-1 molecular sieve coating is coated onto the honeycomb ceramic, followed by a first drying and a first calcination to obtain the carrier;

[0033] (2) The carrier is contacted with a precursor solution containing precious metals and ytterbium, followed by separation, second drying, second calcination, and reduction.

[0034] In this invention, it is understood that those skilled in the art can control the reduction conditions to reduce the noble metal, thereby obtaining the monolithic catalyst of this invention containing active components including the noble metal and ytterbium oxide.

[0035] According to the present invention, the contact between the carrier and the platinum-palladium-ytterbium precursor solution can be selected as needed to be carried out under static (e.g., static impregnation) or dynamic conditions (e.g., stirring), as long as the purpose of the present invention can be achieved, the present invention has no special limitations.

[0036] In this invention, the catalyst prepared using the method of this invention has high activity and stability.

[0037] According to the present invention, the raw materials for providing the TS-1 molecular sieve coating can be mixed into a coating liquid and coated onto the honeycomb ceramic as needed. In some embodiments, the raw materials for providing the TS-1 molecular sieve coating are stirred, mixed, and gel-milled to obtain a coating liquid containing TS-1 molecular sieve. The mixing and gel-milling methods can be carried out as needed and are not limited in specific terms. For example, stirring and mixing for 0.5-4 hours and gel-milling for 0.5-3 hours are used.

[0038] In this invention, the coating process, including multiple coatings, a first drying, and a first calcination, can be performed depending on the amount of the TS-1 molecular sieve coating. The coating method can be selected from various options, such as spraying, dipping, or brushing.

[0039] In this invention, high-pressure nitrogen can be used to blow out the residual molten metal in the honeycomb ceramic after each coating. This operation is a conventional operation in the field and will not be described in detail in this invention.

[0040] According to the present invention, in order to better bond the TS-1 molecular sieve coating with the honeycomb ceramic, a first drying and a first calcination are performed. As long as the purpose of the present invention can be achieved, the conditions for the first drying and the first calcination in the preparation method are not limited. In some embodiments, the conditions for the first drying include: a first drying temperature of 100-120°C and a first drying time of 1-15 h.

[0041] According to the present invention, in some embodiments, the conditions for the first calcination include: a first calcination temperature of 350-600°C and a first calcination time of 3-8 hours.

[0042] According to the present invention, the first drying and the first calcination can be carried out by selecting a staged heating method as needed. In some embodiments, the first drying is carried out by heating from 20-30°C to 100-120°C at a heating rate of 0.5-1.5°C / min and holding for 1-15 hours, and then the first calcination is carried out by heating from 100-120°C to 350-600°C at a heating rate of 0.5-1.5°C / min and holding for 3-8 hours.

[0043] In this invention, the above-mentioned first drying and first calcination conditions can yield a catalyst support with excellent performance, thereby increasing the activity and stability of the catalyst.

[0044] According to the present invention, in order to further increase the interaction between the components in the catalyst, in some embodiments, the conditions for the second drying include: a second drying temperature of 90-120°C and a second drying time of 1-10 h; in some embodiments, the conditions for the second calcination include: a second calcination temperature of 500-600°C and a second calcination time of 4-8 h.

[0045] According to the present invention, conventional reduction methods in the art can be selected for reduction, and the specific conditions are not particularly limited. In some embodiments, the reduction conditions include: using hydrogen gas with a volume concentration of 5-25% for reduction, and a reduction temperature of 300-400°C. Using the aforementioned embodiments can further improve the performance of the catalyst. Under the aforementioned reduction conditions, noble metals can be reduced to obtain the monolithic catalyst of the present invention containing active components including noble metals and ytterbium oxide. In the present invention, the active sites in the active components are located on the ytterbium atoms in the noble metals and ytterbium oxide.

[0046] In this invention, hydrogen with a volume concentration of 5-25% is used for reduction. Other gases are not particularly restricted, as long as they do not affect the reduction reaction, such as nitrogen.

[0047] According to the present invention, it is understood that the precursor solution containing noble metals and ytterbium refers to the noble metal precursor, the ytterbium precursor, and other optional components dissolved in a solvent, wherein the type of solvent can be selected as needed, including but not limited to water.

[0048] According to the present invention, as long as the purpose of the present invention can be achieved, there is no particular limitation on the concentration of the precursor solution containing noble metals and ytterbium. In some embodiments, the concentration of the noble metal precursor in the precursor solution, calculated as noble metal element, is 0.20-1.5 g / L.

[0049] According to the present invention, in some embodiments, the concentration of the ytterbium precursor in the precursor solution is 0.005-0.05 mol / L. Using the aforementioned embodiments, the performance of the catalyst can be further improved.

[0050] According to some preferred embodiments of the present invention, the precious metal includes platinum and palladium.

[0051] According to the present invention, the precursors of platinum, palladium, and ytterbium are respectively the raw materials for providing platinum, palladium, and ytterbium. In some embodiments, the precursors of platinum, palladium, and ytterbium are each a soluble acid or a soluble salt.

[0052] According to some preferred embodiments of the present invention, the precursors of platinum and palladium are each selected from one or more of nitrates, acetates, oxalates and soluble acids.

[0053] According to some preferred embodiments of the present invention, the precursor of ytterbium is selected from one or more of nitrates, acetates and oxalates.

[0054] According to the present invention, the TS-1 molecular sieve can be a commonly used molecular sieve in the art, which can be obtained commercially or by self-production. There is no special restriction on its source. In some embodiments, the preparation method of the TS-1 molecular sieve includes: sequentially contacting tetraethyl silicate with an aqueous solution of tetrapropylammonium hydroxide, a solution containing tetrabutyl titanate and phosphoric acid, followed by crystallization and calcination.

[0055] According to the present invention, the contacting methods of tetraethyl silicate with the aqueous solution of tetrapropylammonium hydroxide, the solution containing tetrabutyl titanate, and phosphoric acid can be selected as needed, for example, contacting under static or dynamic (e.g., stirring) conditions.

[0056] According to the present invention, the concentration of the tetrapropylammonium hydroxide aqueous solution can be selected as needed. In some embodiments, the concentration of the tetrapropylammonium hydroxide aqueous solution is 10-25 wt%.

[0057] According to the present invention, the solvent in the solution containing tetrabutyl titanate can be selected as needed without special limitation, including but not limited to isopropanol. In some embodiments, the concentration of tetrabutyl titanate in the solution containing tetrabutyl titanate is 10-15 wt%.

[0058] According to some preferred embodiments of the present invention, the preparation method of TS-1 molecular sieve includes: adding an aqueous solution of tetrapropylammonium hydroxide dropwise to tetraethyl silicate, then adding a tetrabutyl titanate solution dissolved in isopropanol under stirring, stirring for 0.2-1 h after the tetrabutyl titanate solution is added, then adding phosphoric acid dropwise, and continuing to stir for 0.5-2 h after the addition is complete, followed by crystallization and calcination.

[0059] According to the present invention, the dropwise addition method in the preparation method of TS-1 molecular sieve is a commonly used method in the art, and those skilled in the art can choose it as needed. It will not be described in detail in the present invention.

[0060] According to some embodiments of the present invention, the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is (0.3-0.8):1.

[0061] According to some embodiments of the present invention, the molar ratio of tetrabutyl titanate to tetraethyl silicate is (0.005-0.05):1.

[0062] According to some embodiments of the present invention, the molar ratio of phosphoric acid to tetraethyl silicate is (0.02-0.08):1.

[0063] According to the present invention, the crystallization and calcination conditions can be selected as needed. In some embodiments, the crystallization conditions include: a crystallization temperature of 130-180°C and a crystallization time of 4-10 hours.

[0064] According to the present invention, in some embodiments, the calcination conditions include: a calcination temperature of 400-550°C and a calcination time of 4-12 hours.

[0065] In this invention, the TS-1 molecular sieve prepared in the above-mentioned method is used to prepare honeycomb ceramics with a TS-1 molecular sieve coating. At the same time, it interacts synergistically with noble metals and ytterbium, and the resulting catalyst has high activity and stability.

[0066] A third aspect of the present invention provides the application of the above-mentioned catalyst in the catalytic combustion of cyclohexane-containing organic waste gas.

[0067] In this invention, the catalyst exhibits high activity and stability during the catalytic combustion of cyclohexane-containing organic waste gas.

[0068] The fourth aspect of the present invention provides a method for catalytic combustion of cyclohexane-containing organic waste gas, the method comprising: introducing oxygen-containing gas and contacting the above-mentioned catalyst with the cyclohexane-containing organic waste gas at a temperature of 200-450°C.

[0069] According to the present invention, the cyclohexane content in the cyclohexane-containing organic waste gas is 500-15000 mg / m³. 3 .

[0070] According to the present invention, any oxygen-containing gas that can promote combustion is applicable to the system of the present invention, and the present invention has no special limitations on this. In some embodiments, the oxygen-containing gas includes a mixture of nitrogen and oxygen or air.

[0071] In this invention, the catalyst can effectively catalyze the combustion of cyclohexane-containing organic waste gas. When the conversion rate of cyclohexane reaches more than 99%, the required temperature is lower, indicating that the catalyst in this invention has excellent activity.

[0072] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples:

[0073] The catalyst was evaluated by running it for 15,000 hours under conditions of 10% oxygen by volume. -1 At a gas hourly space velocity (GEV), cyclohexane-containing organic waste gas undergoes catalytic combustion in the presence of a catalyst. The cyclohexane content in the cyclohexane-containing organic waste gas is 8000 mg / m³. 3 ;

[0074]

[0075]

[0076] Example 1

[0077] Synthesis of TS-1 molecular sieve: A tetrapropylammonium hydroxide aqueous solution (concentration 20 wt%) was slowly added dropwise to tetraethyl silicate (molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate was 0.55); then, a tetrabutyl titanate solution (concentration 12.5 wt%) dissolved in isopropanol was added to the above solution under stirring (molar ratio of tetrabutyl titanate to tetraethyl silicate was 0.03); after the addition was complete, the mixture was stirred for 0.5 h, and phosphoric acid was added dropwise to the solution obtained above (molar ratio of phosphoric acid to tetraethyl silicate was 0.055:1). After the addition was complete, the mixture was stirred for 1 h, then crystallized at 160 °C for 6 h, and then calcined at 450 °C for 6 h to obtain TS-1 molecular sieve;

[0078] TS-1 molecular sieve coating: TS-1 molecular sieve, carboxymethyl cellulose, nitric acid and water are mixed in the following mass ratios (TS-1 molecular sieve to carboxymethyl cellulose: 3.3, TS-1 molecular sieve to nitric acid: 13.5, TS-1 molecular sieve to water: 0.28), stirred for 30 minutes, and then gel-milled for 30 minutes to obtain a coating solution; then, honeycomb ceramic (cordierite honeycomb ceramic) is immersed in the above slurry for 30 minutes, removed, and the residual nitric acid in the honeycomb ceramic is blown out with high-pressure nitrogen gas. It is placed at room temperature for 1 hour, and then dried by heating from 20°C to 110°C at a heating rate of 1°C / min and holding for 3 hours. Then, it is calcined by heating from 110°C to 550°C at a heating rate of 1°C / min and holding for 5 hours to obtain honeycomb ceramic with TS-1 molecular sieve coating. The immersion, drying and calcination steps are repeated until a honeycomb ceramic with TS-1 molecular sieve coating content of 4wt% is obtained.

[0079] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a precursor solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0080] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0081] Example 2

[0082] The method according to Example 1 differs in that:

[0083] Repeat the coating, drying, and firing steps until a honeycomb ceramic with a TS-1 molecular sieve coating content of 8wt% is obtained.

[0084] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0085] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0086] Example 3

[0087] The method according to Example 1 differs in that:

[0088] Repeat the coating, drying, and firing steps until a honeycomb ceramic with a TS-1 molecular sieve coating content of 14wt% is obtained.

[0089] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0090] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0091] Example 4

[0092] The method according to Example 2 differs in that:

[0093] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.008 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0094] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0095] Example 5

[0096] The method according to Example 2 differs in that:

[0097] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.047 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb coated with TS-1 molecular sieve in equal amounts. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0098] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0099] Example 6

[0100] The method according to Example 2 differs in that:

[0101] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.14 mg / mL, and the Pd content was 0.31 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0102] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0103] Example 7

[0104] The method according to Example 2 differs in that:

[0105] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.57 mg / mL, and the Pd content was 1.23 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0106] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0107] Example 8

[0108] The method according to Example 2 differs in that:

[0109] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.17 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0110] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0111] Example 9

[0112] The method according to Example 2 differs in that:

[0113] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.54 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0114] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0115] Example 10

[0116] The method according to Example 2 differs in that:

[0117] Replace carboxymethyl cellulose with polyvinyl alcohol (polyvinyl alcohol 124).

[0118] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0119] Example 11

[0120] The method according to Example 2 differs in that:

[0121] Replace carboxymethyl cellulose with polyethylene glycol (PEG 300).

[0122] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0123] Example 12

[0124] The method according to Example 2 differs in that:

[0125] Repeat the coating, drying, and firing steps until a honeycomb ceramic with a TS-1 molecular sieve coating content of 25wt% is obtained.

[0126] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0127] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0128] Example 13

[0129] The method according to Example 2 differs in that:

[0130] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.11 mg / mL, and the Pd content was 0.25 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. After drying at 110 °C for 5 h, it was calcined at 550 °C for 6 h to obtain the monolithic catalyst. Finally, the catalyst was reduced at 350 °C for 3 h in a 10% hydrogen atmosphere.

[0131] Example 14

[0132] In Example 2, the precursor solution was mixed with the coating solution (8 wt% of the honeycomb ceramic based on TS-1 molecular sieve) to obtain a mixed solution. The mixed solution was then coated onto the honeycomb ceramic, dried at 110°C for 5 h, calcined at 550°C for 6 h, and finally reduced at 350°C for 3 h in a 10% hydrogen atmosphere to obtain an integral catalyst.

[0133] Example 15

[0134] TS-1 molecular sieve coating: Mix TS-1 molecular sieve, nitric acid and water at a mass ratio (the mass ratio of TS-1 molecular sieve to nitric acid is 13.5, and the mass ratio of TS-1 molecular sieve to water is 0.28), stir for 30 minutes, and then gel mill for 30 minutes to obtain the coating solution;

[0135] Following the method of Example 2, a honeycomb ceramic containing 8 wt% TS-1 molecular sieve coating was obtained, and then an integral catalyst was prepared according to the method of Example 2.

[0136] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0137] Example 16

[0138] The catalyst was evaluated for 500 hours according to the method in Example 2. Its performance was stable, and the cyclohexane conversion remained at 99% under constant reaction conditions.

[0139] Comparative Example 1

[0140] Alumina coating: Alumina, carboxymethyl cellulose, nitric acid, and water are mixed in the following mass ratios (alumina to carboxymethyl cellulose: 3.3, alumina to nitric acid: 13.5, alumina to water: 0.28). The mixture is stirred for 30 minutes and then ground in a gel for 30 minutes to obtain a coating solution. The honeycomb ceramic is then immersed in the above slurry for 30 minutes and removed. The residual nitric acid in the honeycomb ceramic is blown out with high-pressure nitrogen. The mixture is left at room temperature for 1 hour and then dried by heating from 20°C to 110°C at a rate of 1°C / min and holding for 3 hours. The mixture is then calcined by heating from 110°C to 550°C at a rate of 1°C / min and holding for 5 hours to obtain a honeycomb ceramic with a TS-1 molecular sieve coating. The coating, drying, and calcination steps are repeated until an alumina-coated honeycomb ceramic with an alumina coating content of 8 wt% is obtained.

[0141] Preparation of the monolithic catalyst: Ytterbium nitrate pentahydrate, chloroplatinic acid, and palladium chloride were dissolved in water to obtain a solution (the concentration of ytterbium nitrate pentahydrate was 0.03 mol / L, the Pt content was 0.35 mg / mL, and the Pd content was 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic (cordierite honeycomb ceramic) with an alumina coating in equal amounts. Then, it was dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0142] The organic waste gas containing cyclohexane underwent catalytic combustion reaction under a catalyst, and the reaction results are shown in Table 1.

[0143] Comparative Example 2

[0144] The method according to Example 2 differs in that:

[0145] Preparation of the monolithic catalyst: Chloroplatinic acid and palladium chloride were dissolved in water to obtain a solution (Pt content of 0.35 mg / mL and Pd content of 0.77 mg / mL). The above precursor solution was impregnated onto a honeycomb ceramic coated with TS-1 molecular sieve. The solution was then dried at 110 °C for 5 h, calcined at 550 °C for 6 h, and finally reduced at 350 °C for 3 h in a 10% hydrogen atmosphere to obtain the monolithic catalyst.

[0146] Table 1

[0147]

[0148]

[0149] In Table 1, T1 represents the lowest combustion temperature at which cyclohexane conversion reaches 99%. The lower the temperature, the higher the catalyst activity. The coating amount in Comparative Example 1, calculated as alumina, is 8%. Therefore, both the examples and the comparative examples use the lowest combustion temperature (T1) at which cyclohexane conversion reaches 99% or higher to measure the catalyst performance.

[0150] As can be seen from the results in Table 1, Examples 1-15 of this invention have lower combustion temperatures, indicating that the catalyst performance is superior.

[0151] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A monolithic catalyst for the catalytic combustion of cyclohexane-containing organic waste gas, characterized in that, The catalyst includes a support and an active component; The carrier comprises honeycomb ceramic with a TS-1 molecular sieve coating; the content of the TS-1 molecular sieve coating is 6-14 wt%, based on the mass of the honeycomb ceramic. The active components include noble metals and ytterbium oxide; The precious metals are platinum and palladium. The molar ratio of platinum to palladium in the catalyst is (0.1-0.5):1, calculated by the elemental composition of platinum and palladium. The ytterbium content in the catalyst is 0.2-2 g / L, calculated by the volume of the support and the elemental composition of ytterbium.

2. The catalyst according to claim 1, wherein, The titanium content in the catalyst is 0.1-5 g / L, based on the support volume and titanium element content; and / or The raw materials for providing TS-1 molecular sieve coatings include coating solutions containing TS-1 molecular sieves.

3. The catalyst according to claim 2, wherein, The titanium content in the catalyst is 0.3-2.6 g / L, based on the volume of the support and the amount of titanium.

4. The catalyst according to claim 3, wherein, The titanium content in the catalyst is 1-2.6 g / L, based on the volume of the support and the amount of titanium.

5. The catalyst according to claim 2 or 3, wherein, The coating liquid includes TS-1 molecular sieve, pore-forming agent, viscosity modifier and water.

6. The catalyst according to claim 5, wherein, The mass ratio of TS-1 molecular sieve to water is (0.05-0.8):1; and / or The mass ratio of TS-1 molecular sieve to pore-forming agent is 1:(0.1-0.5); and / or The mass ratio of TS-1 molecular sieve to viscosity modifier is 1:(0.02-0.18); and / or The pore-forming agent is selected from one or more of polyvinyl alcohol, carboxymethyl cellulose, hexadecyltrimethylammonium bromide, polyethylene glycol, P123 polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and poloxamer; and / or The viscosity modifier is selected from one or more of nitric acid, acetic acid, boric acid, phosphoric acid, and oxalic acid.

7. The catalyst according to claim 6, wherein, The viscosity modifier is nitric acid.

8. The catalyst according to claim 1 or 2, wherein, The palladium content in the catalyst is greater than 100 mg / L, based on the support volume and palladium element content. And / or, Based on the support volume and ytterbium element, the ytterbium content in the catalyst is 0.3-1.8 g / L.

9. The catalyst according to claim 8, wherein, The palladium content in the catalyst is 120-1600 mg / L, based on the support volume and palladium element content.

10. The catalyst according to claim 9, wherein The palladium content in the catalyst is 120-400 mg / L, based on the support volume and palladium element.

11. A method for preparing a monolithic catalyst according to any one of claims 1-10, characterized in that, The method includes: (1) The raw material for providing the TS-1 molecular sieve coating is coated onto the honeycomb ceramic, followed by a first drying and a first calcination to obtain the carrier; (2) The carrier is contacted with a precursor solution containing precious metals and ytterbium, followed by separation, second drying, second calcination, and reduction.

12. The preparation method according to claim 11, wherein, The conditions for the first drying include: a first drying temperature of 100-120℃ and a first drying time of 1-15 hours; and / or The conditions for the first roasting include: a first roasting temperature of 350-600℃ and a first roasting time of 3-8 hours; and / or The conditions for the second drying include: a second drying temperature of 90-120℃ and a second drying time of 1-10 hours; and / or The conditions for the second roasting include: a second roasting temperature of 500-600℃ and a second roasting time of 4-8 hours; and / or The reduction conditions include: using hydrogen gas with a volume concentration of 5-25% for reduction, and a reduction temperature of 300-400℃.

13. The preparation method according to claim 11 or 12, wherein, In the precursor solution, the concentration of the noble metal precursor, calculated as a noble metal element, is 0.20-1.5 g / L; and / or The concentration of ytterbium precursor in the precursor solution is 0.005-0.05 mol / L.

14. The preparation method according to claim 13, wherein, The precious metals include platinum and palladium.

15. The preparation method according to claim 14, wherein, The precursors of platinum, palladium, and ytterbium are each soluble acids or soluble salts.

16. The preparation method according to claim 15, wherein, The precursors for platinum and palladium are each selected from one or more of nitrates, acetates, oxalates, and soluble acids; and / or The precursor of ytterbium is selected from one or more of nitrate, acetate and oxalate.

17. The preparation method according to claim 11 or 12, wherein, The preparation method of TS-1 molecular sieve includes: sequentially contacting tetraethyl silicate with an aqueous solution of tetrapropylammonium hydroxide, a solution containing tetrabutyl titanate, and phosphoric acid, followed by crystallization and calcination.

18. The preparation method according to claim 17, wherein, The molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is (0.3-0.8):1; and / or The molar ratio of tetrabutyl titanate to tetraethyl silicate is (0.005-0.05):1; and / or The molar ratio of phosphoric acid to tetraethyl silicate is (0.02-0.08):1; and / or Crystallization conditions include: a crystallization temperature of 130-180℃ and a crystallization time of 4-10 hours; and / or The roasting conditions include: a roasting temperature of 400-550℃ and a roasting time of 4-12 hours.

19. The application of the catalyst according to any one of claims 1-10 in the catalytic combustion of cyclohexane-containing organic waste gas.

20. A method for catalytic combustion of cyclohexane-containing organic waste gas, characterized in that, The method includes: introducing oxygen-containing gas and contacting the catalyst according to any one of claims 1-10 with cyclohexane-containing organic waste gas at a temperature of 200-450°C.

21. The method according to claim 20, wherein, In organic waste gas containing cyclohexane, the content of cyclohexane is 500-15000 mg / m³. 3 ; and / or Oxygen-containing gases include a mixture of nitrogen and oxygen, or air.

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