Naphthalene-method phthalic anhydride waste gas purification catalyst and preparation method and application thereof
By using a specific combination of metal oxide catalysts, the problem of catalyst poisoning caused by high sulfur content in the waste gas from the phthalic anhydride production process of naphthalene has been solved, achieving efficient purification and long-life waste gas treatment, which is suitable for industrial fields such as steel smelting and aluminum smelting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-07
- Publication Date
- 2026-04-17
AI Technical Summary
The high sulfur content in the waste gas from the naphthalene process for producing phthalic anhydride leads to catalyst poisoning and deactivation, and existing catalysts are difficult to effectively purify the gas, thus impacting environmental protection.
A catalyst composed of platinum oxide, palladium oxide, rare earth oxide, vanadium oxide, tungsten oxide and titanium oxide is loaded on a cordierite honeycomb support in a specific ratio to form catalytic active centers. The rare earth oxides preferentially adsorb sulfur species to form stable sulfates and inhibit damage to active sites.
It achieves efficient decomposition of phthalic anhydride waste gas, has excellent catalytic activity and resistance to sulfur poisoning, extends catalyst life, and is suitable for industrial waste gas purification in steel smelting, aluminum smelting, etc. It is low in cost and simple to operate.
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Figure CN121869355A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically a naphthalene-based phthalic anhydride waste gas purification catalyst, its preparation method and uses, particularly for industrial waste gas purification and environmental protection in steel smelting, aluminum smelting and other fields. Background Technology
[0002] Phthalic anhydride, also known as phthalic anhydride, is an important organic chemical raw material. It is widely used in chemical, pharmaceutical, coating, agricultural, electronics, and fine chemical industries. Currently, the main production processes for phthalic anhydride are the naphthalene process and the o-xylene fixed-bed oxidation process (ortho-process). The ortho-process has a higher production efficiency than the naphthalene process, but my country is rich in coal and poor in oil, and its industrial naphthalene production is stable. Therefore, from an economic perspective, the naphthalene process is cheaper. In recent years, most newly built plants in China have been for the production of phthalic anhydride from industrial naphthalene, and many ortho-process plants have also been converted to the naphthalene process. However, compared to the ortho-process, the waste gas from the naphthalene process is more complex, containing small amounts of phthalic anhydride, maleic anhydride, naphthoquinone, and trace amounts of unconverted naphthalene and other organic compounds. Direct discharge of these substances would cause serious environmental damage.
[0003] Currently, catalytic oxidation technology is the mainstream approach for purifying phthalic anhydride waste gas from the naphthalene process, with the catalyst being the core component. Commonly used catalysts primarily utilize precious metals as active ingredients. However, the sulfur content in the waste gas from the naphthalene process is high, and this high sulfur content can lead to catalyst poisoning and deactivation. This is a key technical challenge in the development of catalysts for purifying phthalic anhydride waste gas from the naphthalene process.
[0004] To address the above problems, this invention is proposed. Summary of the Invention
[0005] The purpose of this invention is to provide a catalyst for purifying phthalic anhydride waste gas from the naphthalene process with excellent catalytic performance and good resistance to sulfur poisoning.
[0006] The phthalic anhydride waste gas produced during the naphthalene process refers to the waste gas / tail gas generated during the preparation of phthalic anhydride using the naphthalene method. It contains small amounts of organic compounds such as phthalic anhydride, maleic anhydride, naphthoquinone, and trace amounts of unconverted naphthalene.
[0007] This application provides a catalyst for purifying phthalic anhydride waste gas from the naphthalene process. The catalyst comprises: a support and active centers supported on the support, wherein the active centers include: platinum oxide and / or palladium oxide, rare earth oxides, vanadium oxides, tungsten oxides, and titanium oxides.
[0008] The active center comprises the following components in the following proportions: platinum oxide and / or palladium oxide 0.1-1 wt%, rare earth oxide 1-15 wt%, vanadium oxide 1-5 wt%, tungsten oxide 1-10 wt%, and titanium oxide 69 wt% to 96.9 wt%.
[0009] The statement "0.1-1 wt% platinum oxide and / or palladium oxide" means that the total mass percentage of platinum oxide and palladium oxide is 0.1-1 wt% of the active center. "When both are present" refers to both platinum oxide and palladium oxide. "When only one is present" refers to the presence of only one of them.
[0010] Preferably, the rare earth element in the rare earth oxide is lanthanum and / or cerium.
[0011] Preferably, the carrier is a cordierite honeycomb.
[0012] A second aspect of this application provides a method for preparing the catalyst described in the first aspect, the method comprising the following steps:
[0013] (1) Prepare an oxalic acid aqueous solution with a mass fraction of 6-9%;
[0014] (2) Add ammonium metavanadate, soluble rare earth salt and tungsten titanium powder to the oxalic acid aqueous solution in step (1) in sequence, heat and stir evenly to obtain a mixed solution;
[0015] The mass ratio of ammonium metavanadate, soluble rare earth salt, soluble platinum salt and / or soluble palladium salt, and tungsten titanium powder is (1.285~6.425): (2.523 g~37.848): (0.014~1.882): (84~99).
[0016] (3) Add binder to the mixed solution prepared in step (2) and stir evenly to obtain slurry;
[0017] The amount of the adhesive added is 10-25% of the volume of the mixed solution;
[0018] (4) The cordierite honeycomb ceramic carrier is immersed in the slurry obtained in step (3), and after being taken out, it is dried at 120-150℃ for 1.5-3h, and then calcined at 450-600℃ for 2-5h to obtain the final catalyst.
[0019] Preferably, the mass ratio of oxalic acid, ammonium metavanadate, soluble rare earth salt, soluble platinum salt and / or soluble palladium salt, and tungsten titanium powder is 6: (1.285~6.425): (2.523 g~37.848): (0.014~1.882): (84~99).
[0020] Preferably, the soluble cerium salt is cerium nitrate, cerium ammonium sulfate, or cerium chloride.
[0021] Preferably, the soluble lanthanum salt is lanthanum nitrate, lanthanum chloride, or lanthanum acetate.
[0022] Preferably, the binder is at least one of aluminum sol and silica sol.
[0023] Preferably, in step (4), the process of soaking and drying the cordierite honeycomb ceramic carrier is repeated once or multiple times until the required coating amount of the carrier is reached. The coating amount is 120-150g of calcined slurry / L cordierite honeycomb ceramic carrier.
[0024] That is, the coating amount is 120-150g per liter of cordierite honeycomb ceramic carrier. This coating amount refers to the mass of the slurry after firing. In this application, the unit of coating amount g / L means g of calcined slurry / L of cordierite honeycomb ceramic carrier.
[0025] Preferably, the immersion temperature in step (4) is room temperature, the immersion time is 20-30 minutes each time, and the number of immersions is 2-3 times.
[0026] The tungsten-titanium powder contains 1-10% WO3 by mass, with the remainder being TiO2.
[0027] The third aspect of this application provides the use of the catalyst described in the first aspect for the catalytic decomposition of phthalic anhydride waste gas from the naphthalene process.
[0028] Preferably, the SO2 volume content in the phthalic anhydride waste gas from the naphthalene process is not less than 300 ppm. The phthalic anhydride content is not less than 1000 ppm.
[0029] At 250℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 70%. At 300℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 98%, more preferably over 98.5%.
[0030] At 350℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 99%, and more preferably over 99.3%.
[0031] At 400℃, the conversion rate of phthalic anhydride in the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 99.5%.
[0032] At 450℃, the conversion rate of phthalic anhydride in the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 99.5%.
[0033] Compared with the prior art, the present invention has the following beneficial effects:
[0034] 1. The catalyst of this application, using specific metal oxides in a specific ratio, exhibits unexpected technical effects: it ensures a high phthalic anhydride conversion rate while simultaneously providing excellent resistance to SO2 poisoning and extending catalyst lifespan. The reasons for the superior performance of this catalyst are as follows: The catalyst's active center is composed of oxides of platinum / palladium, vanadium, rare earth elements, tungsten, and titanium. By introducing tungsten, the electronic structure of titanium dioxide is altered, thereby inhibiting the binding of sulfides to the active sites. Furthermore, by introducing CeO2 and La2O3 rare earth oxides, the catalyst preferentially adsorbs sulfur species, forming stable sulfates, reducing damage to the active components, and effectively enhancing its resistance to sulfur poisoning.
[0035] 2. This application discovers that platinum (palladium) precious metals exhibit high catalytic activity towards phthalic anhydride waste gas from the naphthalene process. Furthermore, the V₂O₅-WO₃ / TiO₂ catalytic system demonstrates good thermal stability and resistance to poisoning, enabling long-term use under high temperatures and complex atmospheres. In addition, vanadium has a strong affinity for sulfur, preferentially adsorbing sulfides to form stable vanadium sulfide, thereby reducing sulfur coverage of platinum active sites.
[0036] 3. The honeycomb support of this invention provides excellent specific surface area and pore structure, ensuring efficient catalytic reactions. Furthermore, the honeycomb support effectively prevents catalyst poisoning and enhances the catalyst's resistance to contamination.
[0037] 4. The phthalic anhydride waste gas purification catalyst provided by this invention has high activity, good resistance to SO2 poisoning, and a long service life. The catalyst preparation process is simple, easy to operate, and low in cost, making it promising for broad industrial applications.
[0038] 5. Comparison of Examples 1-6 and the embodiments illustrates that the active ingredients in this application exhibit a certain synergistic effect, which is necessary to significantly increase the conversion rate by multiples. In particular, in the application scenario of this application, there may be a significant synergistic effect between rare earth metal oxides and vanadium oxides, which is necessary to significantly increase the effect in the embodiments by multiples. This is an unexpected discovery of this application. Attached Figure Description
[0039] Figure 1 The figure shows the sulfur-resistant and catalytic stability performance of catalyst 1. Detailed Implementation
[0040] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in the manual, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials required in the following embodiments and comparative examples are all commercially available.
[0041] A catalyst for purifying phthalic anhydride waste gas from the naphthalene process is provided, using cordierite honeycomb ceramic as a support. The catalytic active center is composed of platinum / palladium oxide, vanadium oxide, rare earth oxide, tungsten oxide, and titanium oxide. The composition of the catalytic active center is as follows: palladium (platinum) oxide 0.1-1 wt%, V2O5 1-5 wt%, rare earth oxide 1-15 wt%, WO3 1-10 wt%, and TiO2 69 wt% to 96.9 wt%.
[0042] In the catalyst preparation method, platinum (palladium) is added in the form of a precursor salt solution, with a content of 0.1-1 wt% of the catalyst mass percentage. V₂O₅ is added in the form of ammonium metavanadate, with a content of 1-5 wt% of the catalyst mass percentage. Rare earth oxides, including at least one of CeO₂ and La₂O₃, are added in the form of soluble salts, with a content of 1%-15% of the catalyst mass percentage. WO₃ and TiO₂ are added in the form of tungsten-titanium powder, with a content of 69%-96.9% of the catalyst mass percentage. The tungsten-titanium powder contains 1-10% WO₃ by mass, with the remainder being TiO₂.
[0043] The catalyst also includes alumina or silica sol after calcination, which is supported on the porous surface of the cordierite honeycomb ceramic.
[0044] The preparation method of the catalyst includes the following steps:
[0045] (1) Prepare an oxalic acid aqueous solution with a mass percentage of 6-9%;
[0046] (2) Add ammonium metavanadate, soluble rare earth, platinum / palladium precursor salt and tungsten titanium powder to the oxalic acid aqueous solution prepared in step (1) in sequence, and heat and stir until uniform;
[0047] (3) Add binder to the mixed solution prepared in step (2) and stir evenly to obtain slurry. The amount of binder added is 10-25% of the volume of the mixed solution.
[0048] (4) The cordierite honeycomb ceramic carrier is immersed in the slurry prepared in step (3), and after being taken out, it is dried at 120-150℃ for 1.5-3h, and then calcined at 450-600℃ for 2-5h in air atmosphere to obtain the final catalyst.
[0049] The tungsten-titanium powder used in this embodiment of the invention contains tungsten trioxide and titanium dioxide, and contains 1-10% WO3 by mass, with the remainder being TiO2.
[0050] In this application, platinum oxide is PtO, palladium oxide is PdO, vanadium oxide is V₂O₅, tungsten oxide is WO₃, titanium oxide is TiO₂, and rare earth oxides include at least one of CeO₂ and La₂O₃.
[0051] This application simulates the phthalic anhydride waste gas from the naphthalene process using a mixed gas atmosphere with 1000 ppm phthalic anhydride, 300 ppm SO2, 5% CO2, 5% H2O, 10% O2, and N2 as the balance gas. All ppm and % values mentioned above are volume concentrations.
[0052] The solid content of the aluminum sol or silica sol in this application is 25% and 30%, respectively.
[0053] Comparative Example 1
[0054] Using commercially available 2wt% Pt / Al2O3 as a control sample, a 2wt% Pt / Al2O3 sample was synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of Al2O3 was weighed, and its water absorption rate was determined. Based on the water absorption rate and the Pt loading of the sample, a Pt(NO3)2 solution was prepared and then impregnated onto an Al2O3 support. After loading, the catalyst was placed at room temperature for 12 h, then transferred to a 100 °C oven for overnight drying. Finally, the temperature was increased to 550 °C in a muffle furnace at a rate of 2 °C / min, and calcined in air at this temperature for 2 h to obtain Pt / Al2O3 powder. The obtained Pt / Al2O3 powder sample was slurried, impregnated onto a cordierite honeycomb ceramic support, and then the impregnation and drying were repeated until the required coating amount of 120 g / L was reached, resulting in control sample 1 (2wt% Pt / Al2O3).
[0055] The active components of this catalyst have the following mass contents: PtO 2%, Al2O3 98%.
[0056] Comparative Example 2
[0057] With 2wt%Pt / WO 3 / TiO2 was used as a control sample and synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of tungsten-titanium powder was weighed and its water absorption rate was determined. Based on the water absorption rate and Pt loading, a Pt(NO3)2 solution was prepared, and then impregnated onto the tungsten-titanium powder support to obtain the loaded catalyst. The loaded catalyst was placed at room temperature for 12 h, then transferred to a 100 °C oven for overnight drying. Finally, it was heated to 550 °C in a muffle furnace at a rate of 2 °C / min and calcined in air at this temperature for 2 h to obtain Pt / WO3.3 / TiO2 powder. The obtained Pt / WO3 3 / TiO2 powder samples were prepared into a slurry, impregnated with a cordierite honeycomb ceramic carrier, and then repeatedly impregnated and dried until the required coating amount of 120 g / L was achieved, resulting in control sample 2 (2 wt% Pt / WO3). 3 / TiO2.
[0058] The active components of this catalyst have the following mass contents: PtO 2%, WO3 8%, TiO2 90%.
[0059] Comparative Example 3
[0060] With 5wt%CeO2 / WO 3 / TiO2 was used as a control sample and synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of tungsten-titanium powder was weighed and its water absorption rate was determined. Based on the water absorption rate and CeO2 loading, a Ce(NO3)4 solution was prepared and then impregnated onto the tungsten-titanium powder support to obtain the loaded catalyst. After being placed at room temperature for 12 h, the loaded catalyst was transferred to a 100 °C oven for overnight drying. Finally, it was heated to 550 °C in a muffle furnace at a rate of 2 °C / min and calcined in air at this temperature for 2 h to obtain CeO2 / WO4. 3 / TiO2 powder. The resulting CeO2 / WO3 3 / TiO2 powder samples were prepared into a slurry, impregnated with a cordierite honeycomb ceramic carrier, and then repeatedly impregnated and dried until the required coating amount of 120 g / L was achieved, resulting in a control sample of 3 wt% CeO2 / WO3. 3 / TiO2.
[0061] The active components of this catalyst have the following mass contents: CeO2 5%, WO3 8%, TiO2 87%.
[0062] Comparative Example 4
[0063] With 3wt% V2O5 / WO 3 / TiO2 was used as a control sample and synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of tungsten-titanium powder was weighed and its water absorption rate was determined; based on the water absorption rate and V2O5 loading, an ammonium metavanadate solution was prepared, and then impregnated onto the tungsten-titanium powder support to obtain the loaded catalyst. The loaded catalyst was placed at room temperature for 12 h, then transferred to a 100 °C oven for overnight drying. Finally, it was heated to 550 °C in a muffle furnace at a rate of 2 °C / min and calcined in air at this temperature for 2 h to obtain V2O5 / WO2. 3 / TiO2 powder sample. The prepared V2O5 / WO 3 / TiO2 powder samples were prepared into a slurry, impregnated with a cordierite honeycomb ceramic carrier, and then repeatedly impregnated and dried until the required coating amount of 120 g / L was achieved, resulting in control sample 4 (3 wt% V2O5 / WO3). 3 / TiO2.
[0064] The active components of this catalyst have the following mass contents: V2O5 3%, WO3 8%, TiO2 89%.
[0065] Comparative Example 5
[0066] With 1wt%Pt / 5wt%CeO2 / WO 3 / TiO2 was used as a control sample and synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of tungsten-titanium powder was weighed and its water absorption rate was determined. Based on the water absorption rate and the loading amounts of CeO2 and Pt, Ce(NO3)4 and Pt(NO3)2 solutions were prepared, and then impregnated onto the tungsten-titanium powder support to obtain the loaded catalyst. After being placed at room temperature for 12 h, the loaded catalyst was transferred to a 100 °C oven for overnight drying. Finally, it was heated to 550 °C in a muffle furnace at a rate of 2 °C / min and calcined in air at this temperature for 2 h to obtain Pt / CeO2 / WO3. 3 / TiO2 powder. The prepared Pt / CeO2 / WO3 3 / TiO2 powder samples were prepared into a slurry, impregnated with a cordierite honeycomb ceramic carrier, and then repeatedly impregnated and dried until the required coating amount of 120 g / L was reached, resulting in control sample 5.
[0067] The active components of this catalyst have the following mass contents: PtO 1%, CeO2 5%, WO3 8%, and TiO2 86%.
[0068] Comparative Example 6
[0069] With 1wt%Pt / 3wt%V2O5 / WO 3 / TiO2 was used as a control sample and synthesized using an equal-volume impregnation method. The preparation method was as follows: 100g of tungsten-titanium powder was weighed and its water absorption rate was determined. Based on the water absorption rate and the loading amounts of V2O5 and Pt, ammonium metavanadate and Pt(NO3)2 solutions were prepared, and then impregnated onto the tungsten-titanium powder support to obtain the loaded catalyst. After being placed at room temperature for 12 h, the loaded catalyst was transferred to a 100 °C oven for overnight drying. Finally, it was heated to 550 °C in a muffle furnace at a rate of 2 °C / min and calcined in air at this temperature for 2 h to obtain Pt / V2O5 / WO3. 3 / TiO2 powder. The obtained Pt / V2O5 / WO... 3 / TiO2 powder samples were prepared into a slurry, impregnated with a cordierite honeycomb ceramic carrier, and then repeatedly impregnated and dried until the required coating amount of 120 g / L was reached, resulting in control sample 6.
[0070] The active components of this catalyst have the following mass contents: PtO 1%, V2O5 3%, WO3 8%, and TiO2 88%.
[0071] Performance testing:
[0072] Comparative samples 1, 2, 3, 4, 5, and 6 were placed in a tubular reactor. The experimental conditions were: phthalic anhydride 1000 ppm, SO2 300 ppm, CO2 5%, H2O 5%, O2 10%, N2 as the equilibrium gas, total gas flow rate 1500 ml / min, and space velocity 30,000 h⁻¹. -1 The reaction temperature ranged from 250℃ to 450℃, and the phthalic anhydride concentration was monitored online. The conversion efficiency of phthalic anhydride with different catalysts is shown in Table 1.
[0073] Example 1
[0074] 6g of oxalic acid was dissolved in water and heated to 80℃ until completely dissolved to prepare a 6wt% oxalic acid aqueous solution. 1.285g of ammonium metavanadate was added to the oxalic acid solution and kept at 80℃ until completely dissolved, stirred for 0.5h. Then, 12.616g of cerium nitrate and 1.405g of platinum nitrate were added to the above solution and kept at 80℃ until completely dissolved. 200ml of water and 94g of tungsten-titanium powder were added to the system and stirred at 80℃ for 0.5h. Aluminum sol (10% by volume of the mixed solution) was added as a binder and stirred at room temperature for 2h to obtain a slurry. A blank cordierite honeycomb ceramic carrier was immersed in the slurry, removed, and the residual liquid in the channels was blown away. It was dried at 120℃ for 1.5h and then calcined in air at 550℃ for 5h to prepare catalyst 1 containing 1% Pt. The active components of catalyst 1 have the following mass contents: PtO 1%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85%.
[0075] The amount of ammonium metavanadate added remained unchanged, but the amount of cerium nitrate added was changed to 2.523 g and 37.848 g, and the amount of tungsten-titanium powder added was 98 g and 84 g, respectively, to prepare a slurry. This slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 150°C for 3 hours, and then calcined in air at 550°C for 5 hours. Catalysts 2 and 3, each containing 1% Pt, were obtained.
[0076] The active components of catalyst 2 have the following mass contents: PtO 1%, V2O5 1%, CeO2 1%, WO3 8%, and TiO2 89%.
[0077] The active components of the catalyst 3 have the following mass contents: PtO 1%, V2O5 1%, CeO2 15%, WO3 7%, TiO2 76%.
[0078] The amount of cerium nitrate added remained unchanged, while the amount of ammonium metavanadate added was changed to 2.57 g and 6.425 g, and the amount of tungsten titanium powder added was 93 g and 90 g, respectively, to prepare a slurry; then it was impregnated with a cordierite honeycomb ceramic carrier, dried at 120℃ for 1.5 h, and then calcined in air at 550℃ for 3 h; catalyst 4 and catalyst 5 containing 1% Pt were obtained respectively.
[0079] The active components of the catalyst are: PtO 1%, V2O5 2%, CeO2 5%, WO3 8%, and TiO2 84%.
[0080] The active components of the catalyst 5 have the following mass contents: PtO 1%, V2O5 5%, CeO2 5%, WO3 8%, and TiO2 81%.
[0081] With the amounts of ammonium metavanadate, cerium nitrate, and tungsten titanium powder remaining constant, the amounts of platinum nitrate added were varied to 0.014 g and 0.725 g, respectively, to prepare slurries. These slurries were then impregnated with cordierite honeycomb ceramic carriers, dried at 120°C for 1.5 h, and then calcined in air at 550°C for 3 h to obtain catalysts 6 and 7 containing 0.1% and 0.5% Pt, respectively.
[0082] The active components of the catalyst are as follows: PtO 0.1%, V2O5 1%, CeO2 5%, WO3 8%, TiO2 85.9%.
[0083] The active components of the catalyst 7 have the following mass contents: PtO 0.5%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85.5%.
[0084] With the amounts of ammonium metavanadate, cerium nitrate, and tungsten titanium powder remaining constant, and 1.882 g of palladium nitrate added, a slurry was prepared. This slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 120°C for 1.5 h, and then calcined in air at 550°C for 3 h to prepare catalyst 8 containing 1% Pd.
[0085] The active components of the catalyst have the following mass contents: PdO 1%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85%.
[0086] The amount of ammonium metavanadate and platinum nitrate added remained unchanged. The cerium salt was replaced with cerium ammonium sulfate or cerium chloride, with addition amounts of 19.419 g and 10.831 g, respectively. The amount of tungsten titanium powder added remained unchanged. A slurry was prepared. The slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 120°C for 1.5 h, and then calcined in air at 450°C for 5 h to prepare catalysts 9 and 10 containing 1% Pt.
[0087] The active components of the catalyst 9 have the following mass contents: PtO 1%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85%.
[0088] The active components of the catalyst 10 have the following mass contents: PtO 1%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85%.
[0089] Performance testing:
[0090] The treated catalysts 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 (Φ30×30mm) were placed in tubular reactors. The experimental conditions were: phthalic anhydride 1000ppm, SO2 300ppm, CO2 5%, H2O 5%, O2 10%, N2 as the balance gas, total gas flow rate 1500ml / min, and space velocity 30,000h⁻¹. -1 The reaction temperature ranged from 250℃ to 450℃, and the phthalic anhydride concentration was monitored online. The conversion efficiency of phthalic anhydride with different catalysts is shown in Table 2.
[0091] Example 2
[0092] 6 g of oxalic acid was dissolved in water and heated to 80 °C until completely dissolved to prepare a 6 wt% oxalic acid aqueous solution. 1.285 g of ammonium metavanadate was added to the oxalic acid solution and stirred at 80 °C until completely dissolved for 0.5 h. Then, 9.969 g of lanthanum nitrate and 1.405 g of platinum nitrate were added to the above solution and stirred at 80 °C until completely dissolved. 200 ml of water and 94 g of tungsten-titanium powder were added to the system and stirred at 80 °C for 0.5 h. Aluminum sol (10% by volume of the mixed solution) was then added as a binder and stirred at room temperature for 2 h to obtain a slurry. A blank cordierite honeycomb ceramic carrier was immersed in the slurry, removed, and the residual liquid in the channels was blown away. The carrier was dried at 120 °C for 1.5 h and then calcined in air at 450 °C for 5 h. Catalyst 11 containing 1% Pt was prepared.
[0093] The active components of catalyst 11 have the following mass contents: PtO 1%, V2O5 1%, La2O3 5%, WO3 8%, and TiO2 85%.
[0094] With ammonium metavanadate and platinum nitrate added at constant amounts, the amounts of lanthanum nitrate and tungsten-titanium powder added were varied to 1.994 g and 29.908 g, respectively, to obtain slurries. These slurries were then impregnated with a cordierite honeycomb ceramic carrier, dried at 120°C for 1.5 h, and then calcined in air at 450°C for 3 h. Subsequently, the slurries were impregnated with a platinum nitrate precursor solution, dried at 80°C for 2 h, and calcined in air at 600°C for 2 h, respectively, to obtain catalysts 12 and 13 containing 1% Pt.
[0095] The active components of the catalyst 12 have the following mass contents: PtO 1%, V2O5 1%, La2O3 1%, WO3 8%, and TiO2 89%.
[0096] The active components of the catalyst 13 have the following mass contents: PtO 1%, V2O5 1%, La2O3 15%, WO3 7%, and TiO2 76%.
[0097] The amount of ammonium metavanadate remained unchanged, while the lanthanum salts were replaced with lanthanum chloride and lanthanum acetate, with addition amounts of 11.442 g and 9.693 g, respectively. The amounts of platinum nitrate and tungsten-titanium powder remained unchanged to prepare a slurry. This slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 120 °C for 1.5 h, and then calcined in air at 450 °C for 3 h. Catalysts 14 and 15 containing 1% Pt were thus prepared.
[0098] The active components of the catalyst 14 have the following mass contents: PtO 1%, V2O5 1%, La2O3 5%, WO3 8%, and TiO2 85%.
[0099] The active components of the catalyst 15 have the following mass contents: PtO 1%, V2O5 1%, La2O3 5%, WO3 8%, and TiO2 85%.
[0100] Performance testing:
[0101] The treated catalysts 11, 12, 13, 14, and 15 (Φ30×30mm) were placed in tubular reactors. The experimental conditions were: phthalic anhydride 1000ppm, SO2 300ppm, CO2 5%, H2O 5%, O2 10%, N2 as the balance gas, total gas flow rate 1500ml / min, and space velocity 30,000h⁻¹. -1 The reaction temperature ranged from 250℃ to 450℃, and the phthalic anhydride concentration was monitored online. The conversion efficiency of phthalic anhydride with different catalysts is shown in Table 2.
[0102] Example 3
[0103] 6g of oxalic acid was dissolved in water and heated to 80℃ until completely dissolved to prepare a 6% oxalic acid aqueous solution. 1.285g of ammonium metavanadate was added to the oxalic acid solution and stirred at 80℃ until completely dissolved for 0.5h. Then, 12.616g of cerium nitrate and 1.405g of platinum nitrate were added to the above solution and stirred at 80℃ until completely dissolved. 200ml of water and 94g of tungsten-titanium powder were added to the system and stirred at 80℃ for 0.5h. 20% of the volume of the mixed solution of silica sol and alumina sol (volume ratio 1:1) was added as a binder and stirred at room temperature for 2h to obtain a slurry. A blank cordierite honeycomb ceramic carrier was immersed in the slurry, removed, and the residual liquid in the channels was blown away. It was dried at 120℃ for 1.5h and then calcined in air at 550℃ for 3h to prepare catalyst 16 containing 1% Pt.
[0104] The active components of the catalyst 16 have the following mass contents: PtO 1%, V2O5 1%, CeO2 5%, WO3 8%, and TiO2 85%.
[0105] With the amounts of ammonium metavanadate, cerium nitrate, and tungsten titanium powder remaining constant, and palladium nitrate added at 1.882 g, a slurry was prepared. This slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 120°C for 1.5 h, and then calcined in air at 550°C for 3 h to obtain catalyst 17 containing 1% Pd.
[0106] The active components of the catalyst 17 have the following mass contents: PdO 1%, V2O5 1%, CeO 25%, WO3 8%, and TiO2 85%.
[0107] The amount of ammonium metavanadate added remained unchanged, while cerium salt was replaced with lanthanum salt (lanthanum nitrate) at a dosage of 9.969 g. The amount of platinum nitrate added remained unchanged, as did the amount of tungsten-titanium powder added, to prepare a slurry. This slurry was then impregnated with a cordierite honeycomb ceramic carrier, dried at 120°C for 1.5 h, and then calcined in air at 550°C for 3 h to prepare catalyst 18 containing 1% Pt.
[0108] The active components of the catalyst 18 have the following mass contents: PtO 1%, V2O5 1%, La2O3 5%, WO3 8%, and TiO2 85%.
[0109] Performance testing:
[0110] The treated catalysts 16, 17, and 18 (Φ30×30mm) were placed in tubular reactors. The experimental conditions were: phthalic anhydride 1000ppm, SO2 300ppm, CO2 5%, H2O 5%, O2 10%, N2 as the balance gas, total gas flow rate 1500ml / min, and space velocity 30,000h⁻¹. -1 The reaction temperature ranged from 250℃ to 450℃, and the phthalic anhydride concentration was monitored online. The conversion efficiency of phthalic anhydride with different catalysts is shown in Table 2.
[0111] Example 4
[0112] Catalysts 3, 12, and 17 were aged with sulfur at 300°C for 50 hours in a mixed gas atmosphere with the following composition: 500 ppm SO2 + 5% CO2 + 5% H2O + 10% O2. 2， N2 is the balance gas, and the gas-air space velocity of the mixture is 30,000 h⁻¹. -1 The sulfur-aged catalysts (Φ30×30mm) were placed in tubular reactors under the same experimental conditions as in Example 1. The conversion efficiency of phthalic anhydride after sulfur aging of different catalysts is shown in Table 3.
[0113] Application Example 1
[0114] Catalyst 1 was loaded into a tubular reactor. The experimental conditions were: phthalic anhydride 1000 ppm, SO2 300 ppm, CO2 5%, H2O 5%, O2 10%, N2 as the balance gas, total gas flow rate 1500 ml / min, and space velocity 30,000 h⁻¹. -1 The reaction temperature was 300℃, and the system operated continuously for 1000 hours, with online monitoring of phthalic anhydride concentration. The sulfur-resistant and stabilizing catalytic performance of catalyst 1 is as follows: Figure 1 As shown, this indicates that the catalyst of this application can operate stably for 1000 hours under high concentration SO2 conditions without any decline in catalytic activity. This demonstrates that the catalyst of this application possesses excellent sulfur resistance stability and catalytic activity.
[0115]
[0116] Table 2
[0117]
[0118] Table 3
[0119]
[0120] As can be seen from Tables 1 and 3:
[0121] 1. At 250℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 70%. At 300℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 98%, more preferably over 98.5%.
[0122] At 350℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 99%, and more preferably over 99.3%.
[0123] At 400℃, the conversion rate of phthalic anhydride in the phthalic anhydride waste gas decomposition catalyzed by this catalyst is over 99.5%.
[0124] At 450℃, the phthalic anhydride conversion rate of the phthalic anhydride waste gas decomposed by this catalyst is over 99.5%.
[0125] The above demonstrates that this catalyst exhibits excellent catalytic activity.
[0126] 2. Comparison of Comparative Examples 1-6 and Examples shows that the active ingredients in this application have a certain synergistic effect to significantly increase the conversion rate. The catalyst in this application, after using specific metal oxides in a specific ratio, has a technical effect that is not expected: it can ensure a high phthalic anhydride conversion rate while also making the catalyst have good resistance to SO2 poisoning and extending the catalyst's service life.
[0127] Therefore, this application utilizes a combination of metal oxides
[0128] Table 4-6 summarizes the experimental conditions for the examples.
[0129]
[0130]
[0131]
Claims
1. A catalyst for purification of naphthalene phthalic anhydride off-gas, characterized by, The catalyst comprises: a support and active centers supported on the support, wherein the active centers include: platinum oxide and / or palladium oxide, rare earth oxide, vanadium oxide, tungsten oxide and titanium oxide; The active center contains the following components in proportion: palladium oxide and / or platinum oxide 0.1-1 wt%, rare earth oxide 1-15 wt%, vanadium oxide 1-5 wt%, tungsten oxide 1-10 wt%, and titanium oxide 69 wt% to 96.9 wt%.
2. The catalyst for purification of naphthalene phthalic anhydride off-gas according to claim 1, characterized by, The rare earth element in the rare earth oxide is lanthanum and / or cerium.
3. The catalyst for purification of naphthalene phthalic anhydride off-gas according to claim 1, characterized by, The carrier is a cordierite honeycomb; The metal elements in the active center are uniformly distributed.
4. A process for the preparation of a catalyst according to claim 1, characterized in that, The preparation method includes the following steps: (1) Prepare an oxalic acid aqueous solution with a mass fraction of 6-9%; (2) Add ammonium metavanadate, soluble rare earth salt, noble metal precursor salt and tungsten titanium powder to the oxalic acid aqueous solution in step (1) in sequence, heat and stir evenly to obtain a mixed solution. The mass ratio of ammonium metavanadate, soluble rare earth salt, soluble platinum salt and / or soluble palladium salt, and tungsten titanium powder is (1.285~6.425):(2.523~37.848):(0.014~1.882):(84~99). (3) Add binder to the mixed solution prepared in step (2) and stir evenly to obtain slurry; The amount of the adhesive added is 10-25% of the volume of the mixed solution; (4) The cordierite honeycomb ceramic carrier is immersed in the slurry obtained in step (3), and after being taken out, it is dried at 120-150℃ for 1.5-3h, and then calcined at 450-600℃ for 2-5h in air atmosphere to obtain the final catalyst.
5. The method of claim 4, wherein, The soluble cerium salt is cerium nitrate, cerium ammonium sulfate, or cerium chloride.
6. The method of claim 4, wherein, The soluble lanthanum salt is lanthanum nitrate, lanthanum chloride, or lanthanum acetate.
7. The method of claim 4, wherein, The binder is at least one of aluminum sol and silica sol.
8. The method of claim 4, wherein, In step (4), the process of soaking and drying the cordierite honeycomb ceramic carrier is repeated once or multiple times until the required coating amount of the carrier is reached. The coating amount is 120-150g of calcined slurry / L cordierite honeycomb ceramic carrier.
9. The method of claim 4, wherein, The immersion temperature in step (4) is room temperature, and the immersion time is 20-30 minutes each time.
10. The use of the catalyst according to claims 1-3 for catalytic decomposition of phthalic anhydride waste gas from the naphthalene process.