Efficient regeneration method of H beta molecular sieve catalyst based on ozone atmosphere

Abstract

The invention provides a high-efficiency regeneration method of an H beta molecular sieve catalyst based on an ozone atmosphere, which utilizes high oxidation activity and excellent diffusivity of ozone, preferably, water vapor is doped in the ozone atmosphere, so that the problems of framework desilication, B acid site loss and the like caused by high-temperature roasting during regeneration of the existing H beta molecular sieve catalyst can be solved, and the regeneration efficiency of the H beta molecular sieve catalyst is improved. The deep and uniform removal of the deposited carbon is realized under a mild condition, and the removal rate is gt; according to the present invention, with the molecular sieve, the crystal structure, the pore structure and the key acid center of the B acid can be almost perfectly maintained, such that the catalytic activity and the shape selectivity can be completely recovered so as to maximally recover and maintain the catalytic performance of the H beta molecular sieve, and the regenerated catalyst can significantly maintain the catalyst pore structure and the protonic acid activity, the conversion rate in the acylation reaction of anisole and anhydride is gt; the selectivity is gt; the cycle life is prolonged by more than 3 times, and the method has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of industrial catalysis and chemical process engineering technology, specifically relating to a method for regenerating deactivated heterogeneous catalysts, particularly a method that uses ozone (O3) as a mild oxidizing medium to efficiently remove coke deposits on the inner and outer surfaces of Hβ molecular sieve catalysts at low temperatures, thereby restoring their catalytic activity and shape selectivity. Background Technology

[0002] Hβ molecular sieve is a macroporous zeolite with a three-dimensional twelve-membered ring cross-channel structure. Its Brønsted acid is strong and its hydrothermal stability is good. It is widely used in many acid-catalyzed reactions in the fine chemical industry, such as Friedel-Crafts alkylation / acylation, isomerization, esterification, and important processes such as caprolactam synthesis.

[0003] However, during reactions, especially those involving large molecular reactants or products, the large pores of Hβ molecular sieves are prone to coking and deactivation due to the deposition of carbonaceous materials. These carbon deposits are mainly composed of macromolecules such as polynuclear aromatic hydrocarbons, which not only physically block the 0.66×0.67 nm and 0.56×0.56 nm pores, but also chemically cover the key protic acid (B acid) active centers, leading to a rapid decline in catalytic activity and shape selectivity. Frequent catalyst replacements in industrial applications result in high production costs.

[0004] Currently, the conventional method for regenerating Hβ molecular sieve catalysts is high-temperature calcination, which typically involves burning off carbon deposits by introducing air at 500-600℃. However, this method has the following significant drawbacks when used for Hβ molecular sieve regeneration: (1) Accelerated framework desilication and structural collapse: Hβ molecular sieves are sensitive to high temperatures, especially high-temperature water vapor. High-temperature regeneration will exacerbate framework desilication, leading to a decrease in specific surface area, partial destruction of the pore structure, and irreversible reduction of strong acid centers. This is the fundamental reason why its catalytic performance cannot be fully restored.

[0005] (2) Changes in pore shape selectivity: High temperature may cause changes in the shape of the pore opening, affecting its diffusion shape selectivity for reactants and products, thereby causing a shift in the selectivity of the regenerated catalyst.

[0006] (3) High energy consumption and safety hazards: Like other molecular sieves, the high-temperature process consumes a lot of energy, and the strong exothermic effect of carbon combustion poses a risk of "runaway temperature".

[0007] (4) Uneven regeneration: Oxygen has difficulty penetrating into the partially blocked cross channels, resulting in a large gradient of carbon content inside and outside the catalyst after regeneration, and uneven activity recovery.

[0008] Therefore, developing a green regeneration method that can efficiently regenerate Hβ molecular sieves at low temperatures while perfectly preserving their crystal structure, acid centers, and intrinsic shape selectivity is of great significance for improving the economy and sustainability of related fine chemical processes. Summary of the Invention

[0009] The purpose of this invention is to address the problems of framework desilication and Brønsted acid site loss caused by high-temperature calcination during the regeneration of existing Hβ molecular sieve catalysts, based on existing technologies. This invention provides a highly efficient regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere. Utilizing the high oxidizing activity and excellent diffusivity of ozone, preferably by doping the ozone atmosphere with water vapor, deep and uniform removal of carbon deposits is achieved under mild conditions, with a removal rate >98.5%. This method almost perfectly preserves the crystal structure, pore texture, and key Brønsted acid sites, thereby completely restoring the catalytic activity and shape selectivity. This maximizes the recovery and maintenance of the catalytic performance of the Hβ molecular sieve. The regenerated catalyst significantly retains the catalyst's pore structure and protonic acid activity, achieving a conversion rate >85% and selectivity >88% in the acylation reaction of anisole and anhydride, with a cycle life increased by more than 3 times. It is suitable for catalyst regeneration in industrial isomerization, etherification, alkylation, and other processes, and has broad industrial application prospects.

[0010] The technical solution of the present invention is as follows: A highly efficient regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere; (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing ozone is introduced, with the gas space velocity (GHSV) controlled at 1000-3000 h⁻¹. -1 Regeneration is carried out at a pressure of 0.1-1 MPa and at a temperature of 50-300℃. (3) Post-treatment: After regeneration, the mixed air is replaced with inert gas and purged for 6-20 hours under the same conditions, and then cooled to 20-30℃ to obtain the regenerated catalyst.

[0011] For the purposes of this invention, in step (1), the drying temperature is 50-300℃, and may be, but is not limited to, 50℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, 250℃, 280℃ or 300℃. Preferably, the drying temperature is 80-150℃; more preferably, the drying temperature is 110℃.

[0012] In step (1), the drying time is 6-20 hours, which can be, but is not limited to, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours, preferably 10-14 hours, more preferably 12 hours.

[0013] For the purposes of this invention, in step (2), the volume fraction of ozone in the mixed air introduced is 2%-20%, which may be, but is not limited to, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, and preferably, the volume fraction of ozone in the mixed air introduced is 4%-16%.

[0014] In a preferred embodiment, in step (2), the introduced mixed air contains ozone and water vapor, wherein the volume fraction of ozone in the introduced mixed air is 2%-20%, preferably 4%-16%. The volume fraction of water vapor in the introduced mixed air is 1%-20%, and may be, but is not limited to, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, more preferably, the volume fraction of water vapor in the introduced mixed air is 2%-12%.

[0015] For the purposes of this invention, in step (2), the gas space velocity is controlled to be 1000-3000 h⁻¹. -1 It can be, but is not limited to, 1000 h -1 1200 h -1 1300 h -1 1400 h -1 1500 h -1 1600 h -1 1700 h -1 1900 h -1 2000 h -1 2200 h -1 2400 h -1 2600 h -1 2800 h -1 or 3000 h -1 Preferably, the gas space velocity is controlled at 1300-2000 h⁻¹. -1 More preferably, the gas space velocity is controlled at 1600 h⁻¹. -1 .

[0016] For the purposes of this invention, in step (2), the pressure is 0.1-1 MPa, which may be, but is not limited to, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa or 1.0 MPa. Preferably, the pressure is 0.1-0.3 MPa, more preferably, the pressure is 0.15-0.25 MPa; particularly preferably, the pressure is 0.2 MPa.

[0017] In this invention, in step (2), the regeneration process is carried out in a fixed-bed reactor, and a mixed gas containing ozone is introduced, preferably a mixed gas containing ozone and water vapor, and the gas space velocity is controlled at 1000-3000 h⁻¹. -1 Regeneration is performed at a pressure of 0.1-1 MPa and a temperature of 50-300°C. More preferably, a mixture of ozone and water vapor is introduced, and the gas space velocity is controlled at 1300-2000 h⁻¹. -1 Preferably, the gas space velocity is 1600 h⁻¹. -1 The pressure is 0.1-0.3 MPa, preferably 0.15-0.25 MPa, more preferably 0.2 MPa; regeneration is carried out at 50-300°C.

[0018] In step (2), a multi-porous sieve plate type gas distributor is used to uniformly introduce mixed air containing ozone. Preferably, when introducing mixed air containing ozone and water vapor, a spray-type water distribution device is used to assist in dispersing water vapor.

[0019] In step (2), the temperature during regeneration is 50-300℃, which may be, but is not limited to, 50℃, 70℃, 80℃, 90℃, 100℃, 150℃, 200℃, 250℃ or 300℃; the regeneration time is 1-10 hours, which may be, but is not limited to, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 7 hours, 9 hours or 10 hours; preferably 2-4 hours.

[0020] In this invention, in step (3), after regeneration, the mixed air is replaced with an inert gas and purged for 6-20 hours under the same conditions. The time range can be, but is not limited to, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours, preferably 10-14 hours, and more preferably 12 hours.

[0021] In a preferred embodiment, the inert gas is nitrogen or argon.

[0022] In this invention, the dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing ozone is introduced. Preferably, a mixture of ozone and water vapor is introduced, and the gas space velocity is controlled at 1000-3000 h⁻¹. -1 The catalyst is regenerated at a pressure of 0.1-1 MPa and a temperature of 50-300℃, allowing ozone molecules to diffuse into the three-dimensional cross-channels of the catalyst, oxidizing and decomposing carbonaceous deposits. This selective oxidation and decomposition of carbonaceous deposits restores the pore accessibility and protonic acid active sites of the catalyst.

[0023] In this invention, the ozone atmosphere refers to a mixed air containing ozone, which is prepared on-site by an ozone generator, with oxygen or dry air as the raw material. Preferably, water vapor is mixed into the ozone atmosphere, which is prepared by mixing ozone gas and saturated water vapor in a certain proportion. After mixing, the mixture is heated to the regeneration temperature by a preheater before being introduced into the fixed-bed reactor.

[0024] The advantages of using the technical solution of this invention are as follows: This invention addresses the problems of framework desilication and loss of Brønsted acid sites caused by high-temperature calcination during the regeneration of existing Hβ molecular sieve catalysts. It provides a highly efficient regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere. Utilizing the high oxidizing activity and excellent diffusivity of ozone, preferably by doping the ozone atmosphere with water vapor, deep and uniform removal of carbon deposits is achieved under mild conditions, with a removal rate >98.5%. This method almost perfectly preserves the crystal structure, pore texture, and key Brønsted acid centers, thereby completely restoring the catalytic activity and shape selectivity. This maximizes the recovery and maintenance of the catalytic performance of the Hβ molecular sieve. The regenerated catalyst significantly retains the catalyst's pore structure and protonic acid activity, achieving a conversion rate >85% and selectivity >88% in the acylation reaction of anisole and anhydride, with a cycle life increased by more than 3 times. It is suitable for catalyst regeneration in industrial isomerization, etherification, alkylation, and other processes, and has broad industrial application prospects. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process for the efficient regeneration method of Hβ molecular sieve catalyst based on ozone atmosphere in this invention. Figure 2 This is a comparison of TG analysis of the deactivated Hβ molecular sieve catalyst and the regenerated Hβ molecular sieve catalyst in Example 1. The left side is the deactivated Hβ molecular sieve catalyst, and the right side is the regenerated Hβ molecular sieve catalyst. In the figure, the black line refers to the weight loss line, and the red line refers to the decomposition temperature line. When the catalyst has residual organic matter on its surface, its decomposition will have a temperature. If the catalyst does not have organic matter, its surface will not have a decomposition temperature. Figure 3This is a comparison of TG analysis of the deactivated Hβ molecular sieve catalyst and the regenerated Hβ molecular sieve catalyst in Comparative Example 1; the left side is the deactivated Hβ molecular sieve catalyst; the right side is the regenerated Hβ molecular sieve catalyst; in the figure, the black line refers to the weight loss line, and the red line refers to the decomposition temperature line. When the catalyst has residual organic matter on its surface, its decomposition will have a temperature. If the catalyst does not have organic matter, its surface will not have a decomposition temperature. Figure 4 These are the FI-TR spectra of the regenerated Hβ zeolite catalyst in Example 1, the regenerated Hβ zeolite catalyst in Comparative Example 1, and the unregenerated Hβ zeolite catalyst in Comparative Example 2. Figure 5 These are the FI-TR spectra of the regenerated Hβ zeolite catalyst in Example 5, the regenerated Hβ zeolite catalyst in Comparative Example 1, and the unregenerated Hβ zeolite catalyst in Comparative Example 2. Figure 6 This is a comparison of the product activities of the regenerated Hβ molecular sieve catalysts in Examples 1, 4, 5, 10 and Comparative Example 1; Figure 7 These are the XRD patterns of the Hβ molecular sieve catalysts regenerated in a pure ozone atmosphere in Examples 1-4; Figure 8 These are XRD patterns of the Hβ molecular sieve catalysts regenerated in a low-concentration ozone atmosphere in Examples 5-8; Figure 9 The images show the XRD patterns of the Hβ molecular sieve catalysts regenerated in a high-concentration ozone atmosphere in Examples 9-12. Detailed Implementation

[0026] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0027] In the embodiments and comparative examples of this invention, the carbon-deactivated Hβ molecular sieve catalyst is an Hβ molecular sieve catalyst that has been deactivated after being used in a Friedel-Crafts acylation reaction with fresh, undeactivated Hβ molecular sieve catalyst. The fresh, undeactivated Hβ molecular sieve catalyst is sourced from Zhuoran Environmental Protection Technology (Dalian) Co., Ltd., and has a silicon-to-aluminum ratio of 75.

[0028] For example, using fresh, undeactivated Hβ molecular sieve catalyst in the Friedel-Crafts acylation reaction of anisole and acid anhydride, with an anisole to acetic anhydride molar ratio of 3:1 as an example, the specific reaction conditions are as follows: Anisole (32.44 g, 0.3 mol) and acetic anhydride (10.21 g, 0.1 mol) were poured into a three-necked flask and stirred until homogeneous. Then, 1 g of fresh, undeactivated Hβ molecular sieve catalyst was added to the three-necked flask. The resulting mixture was heated to 120 °C and stirred for 2 h. A sample was taken for chromatographic analysis. The results showed that the selectivity of the product (p-methoxyacetophenone) was 88.36% and the conversion rate of acetic anhydride was 88.21%.

[0029] Hβ molecular sieve catalysts that are deactivated by carbon deposition are defined as those that meet any one of the following three criteria: (1) Under standard Friedel-Crafts acylation reaction conditions, when the yield decreases by more than 25% compared to the initial value after the fresh catalyst or the previous regeneration cycle, or when the reaction temperature is forced to increase by more than 15°C to maintain the same conversion level. (2) If the total loss on ignition (excluding physical water absorption) of the catalyst sample as determined by TGA corresponds to a carbon deposition content of more than 6 wt%, and the peak temperature of the maximum weight loss rate on its DTG curve shifts more than 80°C to the high-temperature region compared to the characteristic temperature of the carbon deposition precursor (“soft carbon”). (3) If the characteristic wavenumber for characterizing typical organic adsorbents (e.g., p-methoxyacetophenone at 1507 cm⁻¹) is... -1 With 1360 cm -1 The presence of significant absorption peaks (near the catalyst surface) confirms the coverage and accumulation of reactants, products, or their deep condensation products on the catalyst surface and within the pores. In the embodiments and comparative examples of this invention, taking the Friedel-Crafts acylation reaction of the above-mentioned anisole and acetic anhydride (molar ratio of 3:1 as an example), the yield of the carbon-deactivated Hβ molecular sieve catalyst used, under the same conditions, decreased by 30% compared to the fresh catalyst; the characteristic temperature shifted to the high-temperature region by more than 550°C; and characteristic peaks of organic matter appeared.

[0030] The criteria for judging deactivated catalysts are as follows: catalyst deactivation can be judged from two aspects: reaction performance and intrinsic changes in the catalyst. First, activity evaluation is a direct performance criterion for deactivation. Under standard Friedel-Crafts acylation reaction conditions, when the yield decreases by more than 25% compared to the initial value after fresh catalyst or the previous regeneration cycle, or when the reaction temperature required to maintain the same conversion level is forced to increase by more than 15°C, it can be determined that the catalyst has undergone significant deactivation. Second, thermogravimetric analysis (TGA) provides a quantitative indicator of the degree of deactivation. If the total loss on ignition (excluding physical water absorption) of the catalyst sample, as determined by TGA, corresponds to a carbon deposition content exceeding 6 wt%, and the peak temperature of the maximum weight loss rate on its TGA curve shifts more than 80°C to the high-temperature region compared to the characteristic temperature of the carbon deposition precursor ("soft carbon"), it indicates that dense and difficult-to-remove "hard carbon" has been formed in the catalyst channels, which is the essential reason for the impeded mass transfer and physical coverage of active sites. Finally, Fourier transform infrared spectroscopy provides direct evidence for revealing physical deactivation caused by carbon deposition. Infrared spectroscopy scanning of the deactivated catalyst can detect characteristic absorption peaks of adsorbed organic deposits on the surface and within the pores. If the characteristic wavenumbers for typical organic adsorbates (e.g., p-methoxyacetophenone at 1507 cm⁻¹) are used to characterize these deposits... -1 With 1360 cm -1 The presence of significant absorption peaks (near) confirms the coverage and accumulation of reactants, products, or their deep condensation products on the catalyst surface and within the pores. This is especially true when characteristic peaks representing molecular sieve framework vibrations (e.g., ~1100 cm⁻¹) are observed. -1 and ~460 cm -1 When the Si-O-Si / Si-O-Al stretching vibrations at the surface are significantly weakened or broadened due to organic matter coverage, it can further confirm that carbon deposits have severely hindered the contact between reactants and active surfaces. Therefore, the significant appearance of characteristic peaks of organic matter in the infrared spectrum and the attenuation of characteristic peaks of the framework, combined with the decrease in reaction activity and thermogravimetric analysis results, together constitute a complete chain of evidence for determining that the catalyst is deactivated due to physical blockage of the pores.

[0031] Determining the success of Hβ molecular sieve catalyst regeneration requires systematic verification of its reaction performance and physicochemical properties, forming a closed loop with deactivation criteria. First, catalytic activity must be substantially restored: after regeneration, under standard Friedel-Crafts acylation conditions, the conversion rate of key reactants should recover to over 95% of the initial value of the fresh catalyst, and the reaction temperature required to maintain this conversion rate should not exceed the normal operating range of the fresh catalyst. Second, carbon deposits must be effectively removed: through thermogravimetric analysis, the residual carbon content of the regenerated catalyst should be less than 0.5 wt%, and the ablation peak on its DTG curve should return to the low-temperature range characteristic of "soft carbon," indicating that the pores have been restored to open. Most importantly, the active phase structure of the catalyst must be preserved and restored: Fourier transform infrared spectroscopy analysis shows that the regenerated catalyst exhibits the characteristic adsorption peak of p-methoxyacetophenone (~1507 cm⁻¹). -1 ~1360 cm -1 The physical blockage should be largely eliminated, and the regeneration process must simultaneously meet the requirements of activity recovery and carbon deposit removal to prove that it not only cleared the physical blockage but also protected the chemical nature of the catalyst, marking the complete success of the regeneration.

[0032] Example 1: Low-temperature regeneration of ozone atmosphere at low concentration A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: 2g of carbon-deactivated Hβ molecular sieve catalyst was dried at 110°C for 12 hours in a nitrogen atmosphere to remove physically adsorbed water.

[0033] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing 4% ozone is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0034] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0035] Example 2: High-temperature regeneration of ozone atmosphere at low concentration A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: 2g of carbon-deactivated Hβ molecular sieve catalyst was dried at 110°C for 12 hours in a nitrogen atmosphere to remove physically adsorbed water.

[0036] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing 4% ozone is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0037] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0038] Example 3: Low-temperature regeneration of ozone atmosphere at high concentrations A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0039] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing 16% ozone is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0040] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0041] Example 4: High-temperature regeneration of ozone atmosphere under high concentration A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water; (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing 16% ozone is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0042] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0043] Example 5: Low-concentration ozone-low-water-content water vapor coupled atmosphere low-temperature regeneration A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0044] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 4% ozone and 2% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0045] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0046] Example 6: High-Temperature Regeneration of Low-Concentration Ozone-Low-Water-Content Water Vapor Coupled Atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0047] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 4% ozone and 2% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0048] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0049] Example 7: Low-concentration ozone-high-water-content water vapor coupled atmosphere low-temperature regeneration A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water; (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 4% ozone and 12% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0050] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0051] Example 8: High-Temperature Regeneration of Low-Concentration Ozone-High-Water-Content Water Vapor Coupled Atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0052] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 4% ozone and 12% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0053] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0054] Example 9: Low-temperature regeneration of a high-concentration ozone-low-water-content water vapor coupled atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0055] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 16% ozone and 2% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0056] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0057] Example 10 High-temperature regeneration of a high-concentration ozone-low-water-content water vapor coupled atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0058] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 16% ozone and 2% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0059] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0060] Example 11 Low-temperature regeneration of a high-concentration ozone-high-water-content water vapor coupled atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0061] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 16% ozone and 12% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 50°C for 2 hours.

[0062] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0063] Example 12 High-temperature regeneration of a high-concentration ozone-high-water-content water vapor coupled atmosphere A low-temperature, high-efficiency regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere for 12 hours to remove physically adsorbed water.

[0064] (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and a mixture of air containing 16% ozone and 12% water vapor is introduced, with the gas space velocity controlled at 1500 h⁻¹. -1 The pressure was 0.2 MPa, and the regeneration was carried out at a temperature of 300℃ for 2 hours.

[0065] (3) Post-treatment: After regeneration, nitrogen gas is introduced and purged for 12 hours under the same conditions to remove the residual reaction gas in the fixed bed reactor. Then, the reactor is naturally cooled to 20-30°C under a nitrogen atmosphere. The regenerated catalyst is then taken out, sealed and stored for testing.

[0066] Comparative Example 1: High-Temperature Calcination Regeneration Regeneration target: Deactivated Hβ molecular sieve catalyst from the same batch as in Example 1; Regeneration step: Weigh 2g of carbon-deactivated Hβ molecular sieve catalyst, spread it evenly in an open ceramic crucible, place it in a temperature-controlled muffle furnace, and calcine it for 5 hours at 550℃ in an air environment. After calcination, allow the muffle furnace and the calcined catalyst to cool naturally to 20-30℃ before removing it.

[0067] Comparative Example 2: Unregenerated catalyst Test subject: The deactivated Hβ catalyst from the same batch as in Example 1 was used for performance comparison.

[0068] Performance Testing and Characterization Comparative Analysis 1. Analysis of carbon deposit removal efficiency and oxidation kinetics (TG-DTG) like Figure 2 and Figure 3 As shown, the final carbon removal rate of the regenerated Hβ molecular sieve catalyst in ozone atmosphere in Example 1 and the regenerated Hβ molecular sieve catalyst after calcination in Comparative Example 1 are both higher than 98.5%, indicating that in terms of total macroscopic carbon removal, the regeneration in ozone atmosphere in Example 1 and the high-temperature calcination in Comparative Example 1 can effectively remove the surface carbon deposits of the catalyst.

[0069] In Examples 2-12, the final carbon removal rate of the Hβ molecular sieve catalyst regenerated in an ozone atmosphere was higher than 98.5%, which was basically the same as in Example 1.

[0070] Table 1 Carbon Deposit Removal Rate

[0071] By analyzing the peak temperature and shape of the weight loss rate reflected in the differential thermogravimetric (DTG) curves, deeper differences in oxidation kinetics can be revealed. Comparative Example 1 exhibits the highest DTG peak temperature (approximately 520°C), indicating that its carbon deposition oxidation requires a high thermal energy input and is a vigorous process. In contrast, the oxidation peak temperatures of the catalyst regenerated using an ozone atmosphere in Example 1 of this invention all shift significantly to the lower temperature range, confirming the strong oxidizing power of ozone at lower temperatures.

[0072] Crucially, the coupled regeneration embodiments that introduce trace amounts of water vapor (such as Examples 5-12) have DTG initiation oxidation temperature and main peak temperature that are further reduced by 10-30°C compared to embodiments that are regenerated in a pure ozone atmosphere (such as Examples 1-4).

[0073] Table 2. DTG initial oxidation temperature and main peak temperature

[0074]

[0075] This phenomenon clearly demonstrates that water vapor acts as an "oxidation promoter" in ozone atmospheres. The mechanism is as follows: water molecules (H2O) can react with ozone (O3), promoting its decomposition and generating hydroxyl radicals (·OH), which have higher oxidation potentials and stronger reactivity. These hydroxyl radicals have a stronger attack capability on large carbon deposit molecules, thereby enhancing the oxidation reaction kinetics at lower temperatures, allowing carbon deposits to be decomposed more efficiently under milder conditions.

[0076] 2. Catalyst crystal structure and texture property recovery analysis (XRD) according to Figure 7 , Figure 8 , Figure 9 XRD analysis showed that the diffraction patterns of the catalysts regenerated by ozone atmosphere (Examples 1-12) were basically the same as those of Comparative Example 1, and the crystallinity retention rate was greater than 99%.

[0077] This indicates that the catalyst regenerated using an ozone atmosphere can effectively remove carbon deposits during the regeneration process while causing minimal damage to the crystal framework of the Hβ molecular sieve. In contrast, the catalyst regenerated in Comparative Example 1 (calcined at 550℃) exhibited a decrease in diffraction peak intensity (approximately 10%) and a rise in the baseline, which are typical characteristics of framework desiliconization and partial amorphization of the structure, originating from thermal stress and hydrothermal effects at high temperatures.

[0078] This reveals the second crucial role of water vapor in catalyst regeneration: "in-situ cleaning" and pore unblocking. During the oxidation reaction, the small-molecule oxidation products (such as CO2 and H2O) and trace amounts of water vapor themselves can carry away and remove incompletely oxidized fragments or polar intermediates deep within the pores, preventing secondary condensation and deposition. This allows for a more thorough restoration of the catalyst's micropores and mesopores, achieving near-perfect regeneration of its texture properties.

[0079] 3. Fourier transform infrared spectroscopy analysis (FT-IR) The adsorption behavior of organic matter on the catalyst surface was analyzed using Fourier transform infrared spectroscopy (FT-IR). Simultaneously, based on... Figure 4 and Figure 5The chromatographic analysis focused on the adsorption characteristics of methoxyacetophenone and its impact on the catalyst's pore structure and activity. In the reaction system without added water, the deactivated catalyst was detected at 1507 cm⁻¹. -1 and 1360 cm -1 The presence of distinct characteristic absorption peaks at the flanks is attributed to the skeletal vibrations of the benzene ring and the bending vibrations of the methyl group in p-methoxyacetophenone, respectively. The peak area continuously increases with the reaction, indicating that the organic compound is irreversibly adsorbed and accumulates on the catalyst surface, ultimately leading to pore blockage and decreased activity. However, after the introduction of water vapor, the intensity of the characteristic peak at the same position significantly weakens, the peak area increases extremely slowly, and it is even undetectable at certain times, indicating that water effectively inhibits the adsorption and retention of p-methoxyacetophenone. The mechanism of water's action mainly includes: competing for adsorption active sites, promoting organic desorption, inhibiting deep coking, and maintaining pore patency. In summary, FT-IR analysis confirms at the molecular level that the water-added condition is significantly better than the anhydrous system. The introduction of water vapor can significantly delay catalyst deactivation caused by organic compound accumulation, providing experimental evidence for improving catalyst stability in industrial catalysis processes.

[0080] 4. Evaluation of the intrinsic catalytic performance of regenerated catalysts (French acylation reaction) The experimental procedures for the Friedel-Crafts acylation reaction of anisole and acetic anhydride in a batch reactor are as follows: First, 32.442 g of anisole (0.3 mol) and 10.209 g of acetic anhydride (0.1 mol) were accurately weighed using an analytical balance and placed in a three-necked flask equipped with a magnetic stirrer. The flask was then placed in an oil bath, and the stirring speed was set to 600 r / min. Subsequently, a condenser, a thermometer, and a nitrogen purging device were installed sequentially on the three-necked flask. After the oil bath temperature reached the set value, 1 g of pre-weighed catalyst (fresh catalyst, deactivated catalyst from Comparative Example 2, and regenerated catalyst from Examples 1-12) was added to the mixed reaction solution. Nitrogen gas was then introduced for gas purging for at least 10 min. The reaction was started after purging. During the reaction, samples were taken at regular intervals. After filtering through a 0.22 μm organic filter, the composition of the sample solution was quantitatively analyzed using gas chromatography combined with an internal standard method to evaluate the catalyst activity.

[0081] The performance of the regenerated catalyst was tested in a batch reactor, and the results are as follows: Figure 6 As shown in Table 3.

[0082] Initial activity (based on acetic anhydride conversion): Comparative Example 2 (unregenerated) showed almost no activity. The regenerated catalyst in Comparative Example 1, due to acidity and damaged pore structure, had lower initial activity compared to the fresh catalyst (acetic anhydride conversion of 87.21%, p-methoxyacetophenone selectivity of 89.36%), and exhibited the fastest deactivation rate. The catalysts regenerated in an ozone atmosphere (Examples 1-12) all recovered to over 85% of the initial activity of the fresh catalyst. Among them, the catalysts regenerated by ozone-water vapor coupling (Examples 5-12) showed the closest activity to the fresh catalyst and the best stability, which is directly related to their highest acid recovery rate and most unobstructed pore structure.

[0083] Product selectivity (based on p-methoxyacetophenone selectivity): The regenerated catalyst in Comparative Example 1 exhibited the lowest selectivity due to changes in its pore structure and acidity, which promoted side reactions such as over-acylation and cracking. The catalysts regenerated in an ozone atmosphere (Examples 1-12) all showed significantly better selectivity than Comparative Example 1, approaching the level of the fresh catalyst. This confirms that the catalyst regeneration method in an ozone atmosphere can fully maintain the inherent shape-selective catalytic properties of Hβ molecular sieves. In particular, the catalysts regenerated by ozone-water vapor coupling, with perfect preservation of acid centers and high pore recovery, showed the most outstanding selectivity.

[0084] Table 3 Performance Tests

[0085] This invention systematically demonstrates that the catalyst regeneration method in an ozone atmosphere can efficiently remove carbon deposits (>98.5%) from Hβ molecular sieve catalysts while almost perfectly preserving their crystal structure, pore texture, and key Brønsted acid centers, thereby completely restoring their catalytic activity and shape selectivity. Its overall performance is significantly better than that of existing high-temperature calcination regenerated Hβ molecular sieve catalysts.

[0086] Most importantly, the regeneration method that couples appropriate amounts of water vapor with ozone plays a decisive role at the molecular level: water molecules promote the decomposition of ozone to generate more oxidizing hydroxyl radicals (·OH), significantly improving the oxidation reaction kinetics at lower temperatures; at the same time, water vapor, as a mild medium, effectively alleviates the local thermal effect of the oxidation process, plays a role in "in-situ stabilizing" the aluminum framework and Brønsted acid sites, and helps to "clean" the finest pores, thereby achieving a synergistic and ultra-efficient recovery of the catalyst's microstructure and macroscopic performance.

[0087] Therefore, the catalyst regeneration method established in this invention, especially the catalyst regeneration method using ozone-water vapor coupling, is a next-generation green regeneration method that can accurately repair catalyst active sites, significantly reduce regeneration energy consumption and thermal damage risk, and ensure the sustainability of the regeneration method, and has broad prospects for industrial application.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications may still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions may be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly efficient regeneration method for Hβ molecular sieve catalysts based on an ozone atmosphere, characterized in that, Includes the following steps: (1) Pretreatment: The carbon-deactivated Hβ molecular sieve catalyst was dried in a nitrogen atmosphere; (2) Regeneration: The dried Hβ molecular sieve catalyst is transferred to a fixed-bed reactor, and mixed air containing ozone is introduced, with the gas space velocity controlled at 1000-3000 h⁻¹. -1 Regeneration is carried out at a pressure of 0.1-1 MPa and at a temperature of 50-300℃. (3) Post-treatment: After regeneration, the mixed air is replaced with inert gas and purged for 6-20 hours under the same conditions, and then cooled to 20-30℃ to obtain the regenerated catalyst.

2. The efficient regeneration method according to claim 1, characterized in that, In step (2), the volume fraction of ozone in the introduced mixed air is 2%-20%, preferably 4%-16%.

3. The efficient regeneration method according to claim 2, characterized in that, In step (2), the introduced mixed air contains ozone and water vapor, wherein the volume fraction of water vapor in the introduced mixed air is 1%-20%, preferably 2%-12%.

4. The efficient regeneration method according to claim 3, characterized in that, In step (2), the mixed air is uniformly introduced through a porous sieve plate type gas distributor, and the gas space velocity is 1300-2000 h⁻¹. -1 The preferred time is 1600h. -1 .

5. The efficient regeneration method according to claim 4, characterized in that, In step (2), the pressure is 0.1-0.3 MPa, preferably 0.15-0.25 MPa, and more preferably 0.2 MPa.

6. The efficient regeneration method according to claim 5, characterized in that, In step (2), the regeneration time is 1-10 hours, preferably 2-4 hours.

7. The efficient regeneration method according to claim 6, characterized in that, In step (2), when the mixed air containing ozone is introduced, a porous sieve plate type gas distributor is used to uniformly introduce the air; when the mixed air containing ozone and water vapor is introduced, a spray-type water distribution device is used to assist in dispersing the water vapor.

8. The efficient regeneration method according to claim 1, characterized in that, In step (1), the drying temperature is 50-300℃, preferably 80-150℃, more preferably 110℃; the drying time is 6-20 hours, preferably 10-14 hours, more preferably 12 hours.

9. The efficient regeneration method according to claim 1, characterized in that, In step (3), the inert gas is nitrogen or argon.

10. The efficient regeneration method according to claim 9, characterized in that, In step (3), the purging time is 10-14 hours, preferably 12 hours.

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