A synergic regeneration method of cyclohexanone ammoximation inactivated titanium silicalite molecular sieve catalyst

Abstract

The application discloses a kind of cyclohexanone ammoximation inactivated titanium silicalite molecular sieve catalysts synergistic regeneration method, the method is first to inactivated TS-1 catalyst is carried out solvent washing and low temperature oxidation, then using ketone oxime class occupant to complete MFI micropore is reversibly occupied;Subsequently with ammonium citrate solution selective peeling non-skeleton titanium silicon species, obtain the peeling solid phase containing silicon hydroxyl defect and the extraction fluid containing endogenous titanium.Peeled solid phase is replaced by solvent and dried, using the defect address agent containing double silane end and containing nitrogen titanium coordination group is handled, and fixed coordination nitrogen content is determined by competitive washing;Endogenous titanium in extraction fluid is captured by chelating resin, elution and coordination stability, and address solid is added according to the molar ratio of titanium and fixed coordination nitrogen 0.20-0.40.Titanium is captured first, and then washes off the titanium species not retained stably.The application is conducive to reducing effective titanium loss, realizing endogenous titanium recycling in the same batch, and improving the distribution and stability of titanium species in the regenerated catalyst.

Description

Technical Field

[0001] This invention relates to the field of titanium-silicon molecular sieve catalyst regeneration technology, specifically to a synergistic regeneration method for cyclohexanone ammonoxime-deactivated titanium-silicon molecular sieve catalysts. Background Technology

[0002] Titanium silicate molecular sieve TS-1 possesses an MFI topology and can catalyze the ammoniation of cyclohexanone using hydrogen peroxide as an oxidant, making it one of the commonly used catalytic materials for the preparation of cyclohexanone oxime. However, in practical applications, the catalyst is in prolonged contact with cyclohexanone, cyclohexanone oxime, ammonia, hydrogen peroxide, water, and organic solvents, which can easily lead to organic matter deposition, pore blockage, and migration or aggregation of titanium species, resulting in a decrease in catalytic activity and hydrogen peroxide utilization.

[0003] For deactivated TS-1 catalysts, existing regeneration methods mainly include solvent washing, calcination, acid treatment, steam treatment, and hydrothermal treatment. Solvent washing and calcination can remove some organic deposits, acid treatment can remove some non-framework titanium, and hydrothermal treatment can adjust the molecular sieve structure and the state of titanium species to a certain extent. For catalysts with titanium loss or damaged titanium sites, existing technologies often use titanium salts, titanate esters, titanium sols, or titanium-containing waste liquids for titanium replenishment.

[0004] Chinese invention patent CN105728035B discloses a method for regenerating deactivated catalysts in a liquid-phase cyclohexanone ammonium oxime process, including alcohol washing, low-temperature calcination under steam and oxygen conditions, treatment with metal-containing acid solution, and subsequent calcination. This method can remove some organic deposits and restore catalyst performance, but it is difficult to distinguish titanium species in different locations and states during acid treatment, potentially causing some loss of effective titanium while removing non-framework titanium, and the titanium in the treated solution is not further utilized. Chinese invention patent CN109592694B discloses a method for treating a catalyst containing titanium-silicon molecular sieves after acid treatment, followed by heat treatment with a silicon source, an added titanium source, and an alkali source. This method requires the addition of titanium salts or titanate esters, and the amount of titanium added is mainly determined based on the overall material ratio, making it difficult to adjust according to the actual defect degree of the deactivated catalyst. The added titanium may also undergo hydrolysis and condensation during liquid-phase treatment, forming non-framework titanium species.

[0005] Chinese invention patent CN104689848B discloses a method for regenerating waste TS-1 titanium-silicon molecular sieves, including removing organic matter from the pores, titanium sol impregnation for titanium replenishment, high-pressure crystallization, and acid treatment. This method uses external titanium sol to replenish titanium species; however, the distribution of the added titanium in the pores, pore openings, and outer surface is affected by the impregnation, hydrolysis, and crystallization conditions, and may still form non-framework titanium that needs subsequent acid washing for removal. Furthermore, high-pressure crystallization has certain requirements for equipment and operating conditions. Chinese invention patent CN103182323B discloses a hydrothermal regeneration method for deactivated titanium-silicon molecular sieves using filtration waste liquid generated during the synthesis process. This method utilizes silicon and titanium species in the synthesis waste liquid; however, the composition of the filtration waste liquid is affected by the synthesis process and batch, and the content of titanium, silicon, and template agent may fluctuate. There is also a lack of direct correlation between the added material and the actual defect degree of the catalyst to be regenerated.

[0006] Overall, existing methods can restore the performance of deactivated TS-1 catalysts to some extent, but problems remain, such as difficulty in distinguishing between effective and non-framework titanium, difficulty in controlling the amount and location of titanium replenishment, easy hydrolysis and aggregation of titanium species, and insufficient utilization of titanium-containing treatment solutions. Therefore, further improvements are still needed to the regeneration method of deactivated titanium silicate molecular sieve catalysts by cyclohexanone ammonoxime oxidation. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects in the prior art, such as the difficulty in selectively distinguishing between effective titanium and non-framework titanium during the regeneration of deactivated titanium-silicon molecular sieves, the ineffective utilization of titanium in the treatment solution, the difficulty in controlling the amount and location of titanium replenishment, and the easy hydrolysis and aggregation of added titanium. The present invention provides a synergistic regeneration method for deactivated titanium-silicon molecular sieve catalysts by cyclohexanone ammonoxime treatment, which can reduce the loss of original effective titanium while removing organic deposits and non-framework titanium species, realize the recycling of endogenous titanium in the same batch, and improve the fixation degree and distribution stability of backfilled titanium in the defect area, thereby effectively solving the problems existing in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a synergistic regeneration method for cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalysts, comprising the following steps:

[0009] (1) The deactivated TS-1 titanium-silicon molecular sieve catalyst derived from the cyclohexanone ammonium oximation reaction was washed with organic solvent and subjected to low-temperature oxidation treatment in an oxygen-containing atmosphere to obtain a pretreated catalyst.

[0010] (2) Contact the pretreated catalyst with a solution containing a ketoxime reversible microporous site-occupying agent, and then remove the free solvent so that the ketoxime reversible microporous site-occupying agent is at least partially retained in the MFI channels of the pretreated catalyst that still maintain the microporous structure, and obtain a microporous site-occupying catalyst.

[0011] (3) The microporous site-occupying catalyst is brought into contact with a selective stripping solution containing ammonium citrate, so that accessible non-framework titanium-silicon species can enter the liquid phase. After solid-liquid separation, a stripped solid phase A containing silicon hydroxyl defects and an extract containing endogenous titanium are obtained.

[0012] (4) Solvent replacement of the stripped solid phase A is performed using alcohol or ketone solvents, followed by drying by vacuum drying, freeze drying or low-temperature fluidized bed drying to obtain the dried stripped solid phase A;

[0013] (5) The dried stripped solid phase A is brought into contact with a defect addressing agent containing two hydrolyzable trialkoxysilane groups and an oxidizable organic linker containing a nitrogen-containing titanium ligand located between the two trialkoxysilane groups, so that the defect addressing agent is fixed to the silanol defect region of the stripped solid phase A through at least one silane end formed by the hydrolysis of the trialkoxysilane groups.

[0014] (6) The solid obtained in step (5) is subjected to competitive washing with anhydrous alcohol or acid-containing anhydrous alcohol to remove the defect addressing agent that is not stably fixed in the silanol defect region, and the content of fixed coordinated nitrogen in the solid after competitive washing is determined.

[0015] (7) Endogenous titanium was captured from extract B using chelating resin, and after washing, elution and coordination stabilization treatment, a stabilized endogenous titanium capture solution was obtained.

[0016] (8) Determine the amount of stabilized endogenous titanium capture liquid added based on the fixed coordinated nitrogen content measured in step (6), so that the ratio of the amount of added titanium to the amount of fixed coordinated nitrogen is 0.20 to 0.40, and make the stabilized endogenous titanium capture liquid contact with the solid after competitive washing, so that the endogenous titanium coordinates with the nitrogen-containing titanium ligand and is captured.

[0017] (9) Before performing the alternating gas-solid solidification treatment of water vapor contact-drying gas purging, the solid obtained in step (8) is washed with anhydrous alcohol or anhydrous alcohol containing titanium coordination stabilizer to remove titanium species that are not stabilized and retained by the defect addressing agent.

[0018] (10) At 90-150°C, the solid obtained in step (9) is subjected to alternating water vapor contact and dry gas purging by gas-solid contact method, and alternating gas-solid solidification treatment is carried out to allow the titanium captured by the defect addressing agent to undergo ligand exchange and limited hydrolysis, and form Ti-O-Si connection with the silanol defect region.

[0019] (11) Remove the ketoxime reversible microporous site-occupying agent, and after the Ti-O-Si connection is formed, perform a staged oxidation treatment on the obtained solid to remove the nitrogen-containing organic part in the defect addressing agent, and obtain the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst.

[0020] In step (8), at least 80 mol% of the titanium added is derived from the extract B obtained in step (3); step (9) is performed before the water vapor contact in step (10); and in step (10), the solid is not immersed in the titanium-containing liquid phase.

[0021] Further, in step (1), the organic solvent washing uses a mixture of tert-butanol and water, with a volume ratio of tert-butanol to water of 1:0.5 to 1:3, a liquid-solid ratio of the mixture to the deactivated TS-1 titanium-silicon molecular sieve catalyst of 3 to 10 mL / g, a washing temperature of 40 to 70 °C, and a single washing time of 1 to 3 h; the low-temperature oxidation treatment includes first treating at 160 to 200 °C for 0.5 to 2 h in an atmosphere containing 1 to 10% by volume oxygen, and then treating at 240 to 290 °C for 1 to 4 h.

[0022] Further, in step (2), the ketoxime reversible microporous site-occupying agent is selected from one or more of acetone oxime, butanone oxime and cyclohexanone oxime, and the amount of ketoxime reversible microporous site-occupying agent fed is 4% to 12% of the dry basis mass of the pretreated catalyst; the pretreated catalyst and the ketoxime reversible microporous site-occupying agent are contacted at 25 to 50°C for 2 to 6 hours, and the free solvent is removed under reduced pressure at 40 to 70°C.

[0023] Further, in step (3), the concentration of ammonium citrate in the selective stripping solution is 0.03-0.15 mol / L, the pH is 4.2-5.5, the liquid-solid ratio of the selective stripping solution to the microporous site-occupying catalyst is 5-12 mL / g, and the microporous site-occupying catalyst and the selective stripping solution are contacted at 45-65℃ for 1-3 h; in step (4), ethanol, isopropanol, tert-butanol or acetone are used to perform solvent replacement on the stripped solid phase A 2-4 times.

[0024] Further, in step (5), the defect addressing agent is N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine; the molar ratio of the defect addressing agent to the silanol groups in the stripped solid phase A is 0.05∶1~0.40∶1, and the molar ratio of water to the hydrolyzable alkoxy groups in the defect addressing agent is 0.1∶1~0.4∶1; after the defect addressing agent is pre-hydrolyzed in an alcohol solvent or toluene at 20~35℃ for 10~60min, it is contacted with the stripped solid phase A at 40~90℃ for 1~8h.

[0025] Further, in step (6), anhydrous ethanol, anhydrous isopropanol, anhydrous ethanol containing 0.01-0.10% by mass acetic acid, or anhydrous isopropanol containing 0.01-0.10% by mass acetic acid are used for 1-4 competitive washings, each lasting 5-30 minutes; after washing with anhydrous ethanol containing acetic acid, the solid is washed at least once with anhydrous ethanol without acid; the mass fraction of fixed coordinated nitrogen in the solid after competitive washing is 0.05%-0.50%.

[0026] Further, step (7) includes: adjusting the pH of extract B to 2.8–4.2, passing extract B through an iminodiacetic acid chelating resin, an aminophosphonic acid chelating resin, or a hydroxamic acid chelating resin; washing the chelating resin that has captured endogenous titanium with deionized water; eluting titanium with a lactic acid aqueous solution with a concentration of 0.2–1.0 mol / L; adding lactic acid, ethylene glycol, or acetylacetone as a titanium coordination stabilizer to the obtained purified endogenous titanium solution, and converting the purified endogenous titanium solution into an ethanol-water mixture or an isopropanol-water mixture with a water mass fraction of 3%–15%, to obtain a stabilized endogenous titanium capture solution with a titanium concentration of 0.005–0.03 mol / L and an apparent pH of 5.0–6.5.

[0027] Further, in step (8), the solid after competitive washing is mixed with the stabilized endogenous titanium capture solution at a solid-liquid ratio of 1:2 to 1:10 and contacted at 15 to 50°C for 1 to 8 hours; in step (9), anhydrous ethanol, anhydrous isopropanol, anhydrous ethanol containing 0.005 to 0.05 mol / L lactic acid, or anhydrous ethanol containing 0.005 to 0.02 mol / L acetylacetone are used for washing 1 to 3 times, each time for 2 to 15 minutes.

[0028] Further, step (10) is carried out at 110-130°C, with a water vapor partial pressure of 5-12 kPa, a single water vapor contact time of 1-5 min, a single dry gas purging time of 8-20 min, and water vapor contact and dry gas purging are alternated 8-12 times; after each water vapor contact, dry gas purging is performed, and the next water vapor contact begins after the water content of the outlet gas is reduced to a set value within the range of 500-2000 ppm.

[0029] In step (11), the reversible microporous site-filling agent of ketoxime is first removed by washing with alcohol solvent and heat treatment in an oxygen atmosphere; then, the temperature is raised to 200-260℃ at 0.5-2℃ / min in an inert atmosphere and held for 1-3h, then raised to 300-380℃ at 0.5-1.5℃ / min in an atmosphere containing 1-3% by volume oxygen and held for 1-3h, and finally treated in air at 430-480℃ for 2-4h; all the titanium used to form Ti-O-Si linkages comes from the same batch of deactivated TS-1 titanium-silicon molecular sieve catalyst extract B, and the co-regeneration method does not add an independent external titanium source.

[0030] Furthermore, the present invention also provides the application of the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst obtained by the above-described synergistic regeneration method in the preparation of cyclohexanone oxime, wherein cyclohexanone, ammonia and hydrogen peroxide are contacted in a liquid-phase reaction system containing the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst to carry out the cyclohexanone ammoniation reaction.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. Before selectively removing non-framework titanium, this invention uses ketoxime-based site-filling agents to reversibly protect the MFI micropores that still maintain their intact structure, so that the subsequent stripping process mainly targets non-framework titanium species on the outer surface, orifice, and defect area. This treatment helps to reduce the possibility of the remaining effective titanium in the intact micropores being removed simultaneously, and retains as many original usable titanium sites as possible while removing undesirable titanium species, thereby improving the selectivity of the regeneration process.

[0033] 2. In this invention, the solid phase and titanium-containing liquid phase obtained by stripping are processed separately, and the endogenous titanium in the same batch in the titanium-containing liquid phase is captured, purified and coordinated to stabilize it, and then used to repair defects in the original deactivated catalyst. Compared with the method of directly adding exogenous titanium salts, titanate esters or titanium sols, this method can improve the utilization of stripped titanium, reduce the discharge of titanium-containing treatment liquid, and reduce the influence of different exogenous titanium precursors on composition and hydrolysis characteristics.

[0034] 3. This invention uses a defect addressing agent containing a bis-silane terminator and a nitrogen-containing coordinating group to pre-locate the silanol defect region, and determines the amount of titanium added based on the fixed coordinating nitrogen content after competitive washing. Thus, the amount of added titanium can match the actual retained fixed nitrogen-containing coordinating sites characterized by the fixed coordinating nitrogen content, and the added titanium can also be preferentially captured in the defect region. This method helps to reduce the random deposition of titanium on the outer surface, pores or intergranular regions of the molecular sieve, and avoids the formation of more oligomeric titanium, polymeric titanium or titanium dioxide species due to excessive titanium addition or uneven distribution.

[0035] 4. In this invention, free titanium and weakly adsorbed titanium are first washed away before alternating gas-solid solidification treatment. Then, gas-solid treatment with alternating water vapor contact and dry gas purging is used to gradually cause the titanium captured by the fixed nitrogen-containing coordination sites to undergo limited hydrolysis and form Ti-O-Si linkages with the adjacent silanol groups. After that, the nitrogen-containing organic linkages of the defect addressing agent are removed. This treatment sequence is beneficial to inhibiting the migration and aggregation of titanium under continuous high humidity or liquid phase conditions, improving the fixation degree and structural stability of backfilled titanium, thereby helping to restore the pore state, active titanium distribution and cyclohexanone ammonium oxime performance of the regenerated catalyst. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow for the synergistic regeneration method of cyclohexanone ammonoxime deactivated titanium silica molecular sieve catalyst according to the present invention.

[0037] Figure 2 This is a schematic diagram of a deactivated titanium-silicon molecular sieve catalyst subjected to microporous site protection and selective exfoliation treatment.

[0038] Figure 3This diagram illustrates the different immobilization states of a defect addressing agent with a bissilane end on the surface of a stripped solid phase, as well as the retention process of nitrogen-containing coordination sites after competitive washing.

[0039] Figure 4 This is a schematic diagram illustrating the process of recovering and purifying endogenous titanium, adding it according to a fixed amount of coordinated nitrogen, and capturing it at fixed nitrogen-containing coordination sites.

[0040] Figure 5 This diagram illustrates how endogenous titanium, captured by fixed nitrogen-containing coordination sites, undergoes alternating gas-solid solidification—water vapor contact and dry gas purging—to form Ti-O-Si bonds, followed by staged oxidation to remove defect addressing agents and nitrogen-containing organic linkages. Detailed Implementation

[0041] The present invention will be further described below with reference to embodiments. These embodiments are used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention; unless otherwise stated, all percentage contents are mass percentages, all gas concentrations are volume concentrations, and all liquid-solid ratios are calculated based on the dry mass of the catalyst.

[0042] In this embodiment, the term "endogenous titanium from the same batch" refers to titanium obtained from the same batch of deactivated TS-1 catalyst to be regenerated through selective stripping, collection, and purification. For deactivated catalysts with basically the same source, operating conditions, and degree of deactivation that are treated together, the titanium recovered from the combined batch is also considered endogenous titanium from the same batch.

[0043] like Figure 1 As shown, the synergistic regeneration method of the present invention sequentially includes pretreatment of deactivated catalyst, reversible MFI microporous site filling, selective stripping of non-framework titanium-silicon species, solvent replacement and drying of the stripped solid phase, defect addressing, competitive washing, collection and purification of endogenous titanium, metering addition of endogenous titanium according to a fixed coordinated nitrogen content, pre-washing before alternating gas-solid solidification, alternating gas-solid solidification with water vapor contact and drying gas purging, removal of site filler, and removal of nitrogen-containing organic linkages of defect addresser.

[0044] I. Raw Materials and Testing Methods

[0045] 1. Deactivated catalyst

[0046] The deactivated catalyst used is the deactivated TS-1 titanium-silicon molecular sieve catalyst discharged from the cyclohexanone ammonium oxime unit; this catalyst comes into contact with cyclohexanone, ammonia, hydrogen peroxide, water, tert-butanol and cyclohexanone oxime during operation;

[0047] The deactivated catalyst was dried to constant weight at 110°C before use; the fresh TS-1 catalyst used in the same apparatus was used as a reference sample.

[0048] 2. Main reagents

[0049] tert-butanol, ethanol, isopropanol, and acetone were analytical grade reagents; the alcohol solvents used for addressing and pre-washing before alternating gas-solid solidification had a water content not exceeding 0.20%; ammonium citrate, citric acid, lactic acid, acetic acid, ethylene glycol, and acetylacetone were all analytical grade reagents.

[0050] The reversible micropore filling agent is acetone oxime, butanone oxime, or cyclohexanone oxime; butanone oxime is preferred.

[0051] The defect addressing agent is preferably N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine, whose structural formula is:

[0052] (EtO)3Si—(CH2)3—NH—CH2CH2—NH—(CH2)3—Si(OEt)3

[0053] The chelating resin used is an iminodiacetic acid type chelating resin, an aminophosphonic acid type chelating resin, or a hydroxamic acid type chelating resin; the resin is acid-washed, water-washed, and activated according to the method specified by the resin supplier before use.

[0054] 3. Preparation of Defect Addressing Agent

[0055] N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine can be used directly if it meets the purity requirements, or it can be prepared according to the following method.

[0056] 44.3 g of 3-aminopropyltriethoxysilane, 20.2 g of triethylamine, and 250 mL of anhydrous acetonitrile were added to a reactor equipped with stirring, condensation, and nitrogen protection. Under nitrogen protection and stirring conditions, 18.8 g of 1,2-dibromoethane was dissolved in 50 mL of anhydrous acetonitrile and added dropwise to the reactor over 1 hour.

[0057] After the addition was completed, the reaction was carried out at 70℃ for 8 hours; after cooling, the generated salt was removed by filtration, and the solvent was removed from the filtrate under reduced pressure at a temperature not exceeding 50℃; the product was washed twice with anhydrous n-hexane and dried under an absolute pressure not exceeding 2 kPa and a temperature not exceeding 80℃ to obtain the bissilane defect addressing agent.

[0058] The structure and composition of the obtained product can be confirmed by nuclear magnetic resonance, infrared spectroscopy and elemental analysis; it should be sealed and stored in a dry environment before use to avoid prolonged contact with moisture in the air.

[0059] The defect addressing agent used in this embodiment undergoes structural and quality verification before use, with a purity of not less than 95% and a moisture content of not more than 0.50% by mass. For self-prepared defect addressing agents, nuclear magnetic resonance, infrared spectroscopy, and elemental analysis are used to confirm that they have bis(trialkoxy)silane terminals and nitrogen-containing ligands. For commercially available products, verification can be performed based on product quality certification documents. The defect addressing agent should be kept clear or homogeneous before use; it should not be used for addressing treatment if it exhibits obvious turbidity, gelation, or insoluble condensation. The diethylenetriamine-type bissilane addressing agent used in Example 4 undergoes structural and quality verification according to the same requirements.

[0060] 4. Structural and composition testing

[0061] The total titanium content of the catalyst was determined by ICP-OES; solid samples were measured after acid digestion, while liquid samples were measured after direct dilution or digestion according to their composition.

[0062] The organic sediment content was determined by thermogravimetric analysis. The sample was first heated in nitrogen to remove adsorbed water and low-boiling substances, and then switched to air treatment. The organic sediment content was calculated based on the mass loss within the corresponding temperature range.

[0063] The crystal structure of MFI was determined by X-ray diffraction; the relative crystallinity of other samples was calculated with the sum of the integral intensities of the main characteristic peaks of the fresh TS-1 sample as 100%.

[0064] Specific surface area and pore volume were determined by low-temperature nitrogen adsorption method; the final regenerated catalyst was degassed under vacuum at 250°C before testing; intermediate samples containing placers or addressing agents were degassed at a lower temperature and used only for relative comparison under the same conditions.

[0065] Titanium species were analyzed using UV-Vis diffuse reflectance spectroscopy and UV-Raman spectroscopy. In the UV-Vis diffuse reflectance spectroscopy, the 210–230 nm region served as an auxiliary signal for tetracoordinated or framework-like titanium, the 260–290 nm region served as an auxiliary signal for oligomeric titanium species, and the 320–350 nm region served as an auxiliary signal for polymeric titanium or TiO2-related species. It is not possible to determine whether titanium has entered the MFI crystal framework based solely on a single absorption region.

[0066] The fixed coordinated nitrogen in the solid after competitive washing was determined by an elemental analyzer; the sample was vacuum dried to constant weight at 60℃ before detection.

[0067] The term "fixed coordinated nitrogen" as used in this specification refers to the residual nitrogen measured by elemental analysis after the addressed solid has been treated according to a prescribed competitive washing procedure and dried to constant weight. As a quantitative indicator of a stable and fixed nitrogen-containing address structure, fixed coordinated nitrogen does not mean that all nitrogen atoms measured at the same time form coordinate bonds with titanium. The amount of substance of fixed coordinated nitrogen is calculated according to the following formula: Amount of substance of fixed coordinated nitrogen = Mass of dried solid after competitive washing × Mass fraction of fixed coordinated nitrogen / 14.0067.

[0068] 5. Capable of determining silanol content

[0069] Take 0.500 g of dried exfoliated solid phase, add 20 mL of anhydrous toluene and 2 mL of hexamethyldisilazane, and reflux at 80 °C for 4 h; after filtration, wash with anhydrous toluene until no unreacted reagents are detected in the washing solution, and dry under vacuum at 120 °C.

[0070] The number of grafted trimethylsilyl groups is calculated based on the increase in solid carbon content before and after treatment, and the approximate silanol content is estimated accordingly. This method is mainly used for calculating the amount of addressing agent added to the same batch of samples.

[0071] The amount of substance with approachable silanol groups is calculated based on the increase in carbon mass in the dry solid before and after silanization treatment; let the dry solid mass before treatment be m0 and carbon mass fraction be w0, and the dry solid mass after treatment be m1 and carbon mass fraction be w1, then the amount of substance with approachable silanol groups n(Si—OH) = (m1w1 - m0w0) / (3 × 12.011); the carbon mass introduced by the blank test under the same conditions is deducted during the calculation, and the conversion is performed according to one trimethylsilyl group corresponding to one approachable silanol group.

[0072] 6. Catalytic performance evaluation

[0073] Add 0.030 mol cyclohexanone, 20 mL tert-butanol, 0.300 g catalyst, and 0.036 mol ammonia water (calculated as NH3) to a reactor equipped with a stirring and reflux condenser. Heat the reaction system to 80 °C and uniformly add an aqueous solution of hydrogen peroxide containing 0.030 mol H2O2 dropwise over 60 min. After the addition is complete, continue the reaction for 2 h.

[0074] After the reaction, the mixture was cooled and filtered. Gas chromatography was used to determine the contents of cyclohexanone, cyclohexanone oxime, and major byproducts. Iodometric titration was used to determine residual hydrogen peroxide. The conversion rate of cyclohexanone and the selectivity of cyclohexanone oxime were calculated using the following formulas:

[0075]

[0076] In the formula, This represents the initial amount of cyclohexanone. This represents the amount of cyclohexanone remaining after the reaction is complete.

[0077] The effective utilization rate of hydrogen peroxide was calculated as the ratio of the theoretical consumption of hydrogen peroxide corresponding to the formation of cyclohexanone oxime to the actual consumption of hydrogen peroxide; the titanium content in the reaction solution was determined by ICP-OES.

[0078] II. Example 1

[0079] In this embodiment, methyl ethyl ketone oxime is used for micropore filling, ammonium citrate is used for selective stripping of non-framework titanium-silicon species, ethylenediamine-type bissilane is used as a defect addressing agent, and iminodiacetic acid-type chelating resin is used to recover endogenous titanium.

[0080] 1. Pretreatment of deactivated catalyst

[0081] Weigh 100.0g of deactivated TS-1 catalyst and add 500mL of a mixture of tert-butanol and water, with a volume ratio of tert-butanol to water of 1:1; stir at 60℃ for 2h and filter; repeat the washing process once under the same conditions.

[0082] The washed catalyst was dried at 110℃ for 6 hours and then loaded into a tubular furnace. Nitrogen gas containing 2% oxygen was introduced, and the temperature was increased to 180℃ at 1℃ / min and held for 1 hour. The temperature was then increased to 280℃ and held for 3 hours. After the treatment was completed, the gas was switched to nitrogen and cooled to room temperature to obtain the pretreated catalyst.

[0083] The detection results of the catalyst before and after pretreatment are shown in Table 1.

[0084] Table 1. Properties of catalysts before and after pretreatment

[0085]

[0086] As shown in Table 1, the pretreatment mainly removed organic deposits, and the total titanium content did not change significantly.

[0087] 2. MFI micropore reversible spacer

[0088] 8.0 g of butanone oxime was dissolved in 150 mL of tert-butanol, and the pretreated catalyst was added. The mixture was stirred at 35 °C for 4 h. The free liquid was removed by filtration, and the mixture was vacuum treated at 60 °C and an absolute pressure not exceeding 10 kPa for 4 h to obtain a microporous site-occupied catalyst.

[0089] Calculations based on the difference in thermogravimetric weight loss before and after the site was determined showed that the actual amount of methyl ethyl ketone oxime retained was approximately 7.3 g, accounting for 91.3% of the feed amount. Under the same low-temperature degassing conditions, the micropore volume decreased from 0.142 cm³ / g to approximately 0.107 cm³ / g, indicating that methyl ethyl ketone oxime was retained in the micropore or pore opening region of the catalyst.

[0090] like Figure 2As shown, the deactivated catalyst may simultaneously contain organic deposits in the pores, non-framework titanium-silicon species on the outer surface or in defect areas, and effective titanium species still retained in the intact MFI micropores. After the ketoxime-based site-filling agent enters the MFI micropores that still maintain their intact structure, it can reduce the extent to which the selective stripping liquid enters the intact micropores and contacts the remaining effective titanium therein. The selective stripping treatment is mainly used to allow the non-framework titanium-silicon species that are accessible in the outer surface, pore openings and defect areas to enter the liquid phase and expose the silanol defects in the solid phase.

[0091] 3. Selective stripping of non-framework titanium-silicon species

[0092] Prepare 800 mL of 0.080 mol / L ammonium citrate aqueous solution, and adjust the pH to 4.8 with citric acid or dilute ammonia.

[0093] The microporous site-occupying catalyst was added to the exfoliation solution and stirred at 250 r / min for 2 h at 55 °C. After the treatment was completed, the mixture was filtered to obtain the exfoliated solid phase and the extract containing endogenous titanium. The exfoliated solid phase was washed rapidly with 100 mL of water at pH 4.8, and the washings were added to the extract.

[0094] Table 2 shows the concentration values ​​of liquid titanium and silicon at different times during the stripping process.

[0095] Table 2 Liquid phase composition during selective stripping process

[0096]

[0097] Based on the initial catalyst containing 29.70 mmol of titanium, 23.82 mmol of titanium was retained in the stripped solid phase, 5.58 mmol of titanium was contained in the main extract, and 0.12 mmol of titanium was contained in the rapid washing solution. The remaining difference came from sampling loss and analytical error. The stripped titanium accounted for approximately 19% of the initial total titanium.

[0098] 4. Stripping solid-phase solvent replacement and drying

[0099] Add 200 mL of tert-butanol to the exfoliated solid phase, stir at room temperature for 30 min, and then filter. Repeat the displacement twice under the same conditions.

[0100] The substituted solid phase was vacuum dried at 55℃ and an absolute pressure not exceeding 10 kPa for 8 hours; the mass of the dried solid phase was approximately 91.2 g; the content of its approachable silanol groups was determined to be approximately 1.06 mmol / g by the silanization weight gain method.

[0101] 5. Defect addressing agent pre-hydrolysis and addressing

[0102] Prepare 400 mL of anhydrous ethanol solution of N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine with a concentration of 0.030 mol / L. The amount of addressing agent used is 12.0 mmol, and the molar ratio of addressing agent to the silanol group in the exfoliated solid phase is approximately 0.12:1.

[0103] Each addressing agent molecule contains six hydrolyzable ethoxy groups; water is added at a molar ratio of water to hydrolyzable ethoxy groups of 0.20:1, and 0.20 mL of glacial acetic acid is added, and the mixture is stirred at 25 °C for 30 min.

[0104] The pre-hydrolysate should remain clear; if visible turbidity or flocculent matter appears, the amount of water added, the amount of acetic acid added, or the pre-hydrolysate time should be reduced.

[0105] The dried exfoliated solid phase was added to the pre-hydrolyzed solution and stirred at 70°C for 4 hours. A reflux condenser was used during the process to reduce ethanol loss. After the reaction was completed, the solution was filtered to obtain the addressed solid.

[0106] like Figure 3 As shown, after limited hydrolysis, the trialkoxysilanes at both ends of the defect addressing agent can be linked to the silanol groups of the stripped solid defect region through at least one silane end; after addressing treatment, addressing agents formed by physical adsorption, hydrogen bonding or liquid-phase polycondensation may also exist in the solid; after removing the unstable addressing agents by competitive washing, the nitrogen-containing groups remaining in the solid constitute the fixed nitrogen-containing coordination sites for subsequent capture of titanium species.

[0107] 6. Competitive washing and determination of fixed coordination nitrogen content

[0108] Wash the addressing solid with 300 mL of anhydrous ethanol containing 0.05% acetic acid for 15 min, then filter; wash again under the same conditions; then wash with 300 mL of neutral anhydrous ethanol for 15 min.

[0109] The solid was vacuum dried at 60℃ for 4 hours; the total nitrogen mass fraction of the solid before competitive washing was 0.34%; the mass of the solid after competitive washing was 96.0 g, the mass fraction of fixed coordinated nitrogen was 0.24%, and the amount of substance of fixed coordinated nitrogen was:

[0110]

[0111] Competitive washing is used to remove addressing agents that are physically adsorbed, weakly bound, or spontaneously condensed in the liquid phase; the nitrogen-containing groups retained after competitive washing constitute fixed nitrogen-containing coordination sites.

[0112] 7. Endogenous titanium capture, elution and stabilization

[0113] Adjust the pH of the extract to 3.5; pack 100 mL of activated iminodiacetic acid chelating resin into a column, and pass the extract through the resin column at a flow rate of twice the resin bed volume per hour.

[0114] The amount of chelating resin used is determined based on the titanium working capacity provided by the resin supplier, ensuring that the theoretical titanium working capacity of the resin is not less than twice the total amount of titanium in the extract. During the sample loading process, the titanium concentration in the effluent is monitored periodically. If significant titanium penetration occurs, the sample loading is stopped and the resin is replaced or added. After washing with water until the conductivity of the effluent is basically stable, lactic acid elution is performed. Elution is terminated when the titanium concentration in two consecutive eluents is lower than 1% of the highest elution concentration. The apparent pH of the alcohol-water system is measured at 25°C using a composite glass electrode as a process control indicator between different batches of stabilized endogenous titanium capture solutions.

[0115] After the sample was loaded, the resin was washed with water at a rate of 3 times the resin bed volume to remove citrate, ammonium salt and soluble silicon; then titanium was eluted with a 0.5 mol / L lactic acid aqueous solution at a flow rate of 0.5 to 1 times the resin bed volume per hour.

[0116] The titanium eluent was concentrated under reduced pressure at a temperature not exceeding 50°C, and anhydrous ethanol was added in batches to continue concentration to complete the solvent conversion. The resulting endogenous titanium solution was adjusted to achieve a Ti concentration of 0.0201 mol / L, a water content of 8.2%, a lactic acid to Ti molar ratio of 2.05:1, and an apparent pH of 5.8.

[0117] The total titanium in the extract was approximately 5.70 mmol. After resin collection and elution, approximately 5.05 mmol of purified endogenous titanium was obtained, with a titanium recovery rate of approximately 88.6%. The stabilized endogenous titanium solution remained clear after standing at room temperature for 24 h, and no precipitation was observed.

[0118] like Figure 4 As shown, the endogenous titanium in the extract obtained by selective stripping is captured by chelating resin, washed with water to remove impurities, eluted and coordinated to stabilize, and then transformed into a stabilized endogenous titanium capture solution. The amount of stabilized endogenous titanium added is determined according to the content of fixed coordinated nitrogen in the solid after competitive washing, so that the amount of titanium added corresponds to the fixed nitrogen-containing coordination sites characterized by the content of fixed coordinated nitrogen. The endogenous titanium is captured after contacting the nitrogen-containing coordination groups in the addressing agent, and the titanium species that are not stabilized and captured are removed by washing before alternating gas-solid solidification treatment.

[0119] 8. Add endogenous titanium according to the fixed coordinated nitrogen content.

[0120] The amount of titanium added is calculated based on a ratio of 0.30 between the amount of titanium added and the amount of nitrogen fixed in place.

[0121]

[0122] The actual amount of endogenous titanium added was 4.92 mmol; the volume of the stabilized endogenous titanium solution was:

[0123]

[0124] 245 mL of stabilized endogenous titanium solution was actually added; all the titanium added in this example came from the extract obtained from the same batch of deactivated catalyst.

[0125] The addressing solid was added to the stabilized endogenous titanium solution and stirred at 150 r / min for 4 h at 30 °C. The mixture was then filtered. The titanium in the residual liquid after capture was 0.72 mmol, and the titanium temporarily retained in the solid was 4.20 mmol.

[0126] 9. Washing before alternating gas-solid solidification

[0127] The solid containing captured titanium was rapidly washed for 8 min with 250 mL of anhydrous ethanol containing 0.010 mol / L lactic acid, and then filtered. The solid was washed again under the same conditions.

[0128] Approximately 0.61 mmol of titanium was detected in both washing solutions; therefore, the amount of backfill titanium entering the subsequent alternating gas-solid solidification step was approximately 3.59 mmol.

[0129] The washed solid was vacuum dried at 60°C for 4 hours; after washing before alternating gas-solid curing, the solid was no longer immersed in or kept in the titanium-containing liquid phase.

[0130] 10. Alternating gas-solid curing process involving water vapor contact and dry gas purging.

[0131] The solid was loaded into a fixed-bed reactor equipped with a gas preheating and steam generation device, dry nitrogen was introduced, and the bed temperature was raised to 120°C.

[0132] The solid catalyst is uniformly packed in the fixed-bed reactor, with the catalyst bed not exceeding 70% of the reactor's effective volume. A temperature monitoring point is set in the middle of the bed. The total volumetric flow rates of water vapor nitrogen and dry nitrogen are kept consistent, and the gas hourly space velocity calculated based on the catalyst bed volume is 200–800 h⁻¹. -1 Water vapor is carried into the bed by nitrogen gas, and the water content of the outlet gas is measured by an online dew point meter or moisture analyzer located downstream of the bed outlet. When changing the treatment scale, the water vapor partial pressure, gas volume hourly space velocity, bed temperature, and single contact and purging time are kept within the corresponding specified ranges.

[0133] Perform 10 water vapor contact-dry gas purging cycles, each cycle including:

[0134] Nitrogen gas with a water vapor partial pressure of approximately 10 kPa was introduced for 3 minutes;

[0135] Stop the steam input and let it stand for 2 minutes;

[0136] Purge with dry nitrogen gas for 12 minutes;

[0137] During the drying and purging phase, monitor the water content of the outlet gas; once the outlet water content drops below 1000 ppm, begin the next water vapor contact; after treatment, cool to below 60°C in dry nitrogen.

[0138] Water vapor contact is used to promote ligand exchange and limited hydrolysis of titanium trapped by the addressing agent, while dry purging is used to remove water and alcohol byproducts and promote the condensation of titanium hydroxyl groups with adjacent silanol groups.

[0139] like Figure 5 As shown, endogenous titanium trapped by fixed nitrogen-containing coordination sites can undergo ligand exchange and limited hydrolysis during water vapor contact, forming a titanium-containing hydroxyl intermediate state. Subsequently, water and alcohol byproducts are removed by purging with dry gas, and the condensation of titanium hydroxyl with adjacent silanol is promoted. After multiple water vapor contacts and dry gas purgings, Ti-O-Si linkages are formed between the titanium species and the defect region. After the formation of this linkage, the nitrogen-containing organic linkages of the defect addressing agent are removed by staged oxidation.

[0140] Figure 5 This invention is used to illustrate the possible titanium species transformation process during alternating gas-solid solidification treatment, and the implementation of this invention is not limited to this mechanism explanation.

[0141] 11. Removal of spacer

[0142] The solid after alternating gas-solid solidification treatment was washed with 300 mL of tert-butanol at 60 °C for 30 min and then filtered. The washing was repeated twice under the same conditions.

[0143] The solid was then placed in nitrogen containing 2% oxygen and treated at 180°C for 1 hour; thermogravimetric analysis showed that the removal rate of the spacer was over 94%.

[0144] 12. Removal and structural stabilization of nitrogen-containing organic linkers in defect addressing agents

[0145] The solid, after removing the spacer, is loaded into an atmosphere furnace and processed according to the following procedure:

[0146] 1. Heat to 240℃ in nitrogen at a rate of 1℃ / min and maintain for 2 hours;

[0147] 2. Switch to nitrogen gas containing 2% oxygen, and raise the temperature to 350℃ at a rate of 1℃ / min, and maintain it for 2 hours;

[0148] 3. Switch to air, raise the temperature to 460℃, and maintain for 3 hours;

[0149] 4. After cooling to 200°C in air, switch to nitrogen and continue cooling to room temperature.

[0150] The synergistically regenerated TS-1 catalyst was obtained after treatment; the final catalyst mass was approximately 92.7 g, the backfilled titanium retention was approximately 3.47 mmol, the total solid titanium was 27.21 mmol, the total titanium content was approximately 1.41%, and the residual nitrogen content was approximately 0.028%.

[0151] The material balance closure of titanium is approximately 99.5%.

[0152] To verify the fixation state of the backfilled titanium, the titanium content, residual nitrogen content, UV-Vis diffuse reflectance spectroscopy, and UV-Raman spectroscopy were measured on the solid before alternating gas-solid solidification, the solid after alternating gas-solid solidification, and the synergistic regeneration catalyst after staged oxidation. X-ray photoelectron spectroscopy was used for auxiliary analysis when necessary. The formation of Ti-O-Si linkages was not judged solely by a single spectral peak, but rather by a comprehensive assessment of the amount of backfilled titanium retained, the stability of titanium before and after the removal of nitrogen-containing organic linkages, the related signals of tetracoordinate or framework titanium, and the related signals of high-polymer titanium.

[0153] 13. Detection results of Example 1

[0154] Table 3 Structural properties before and after regeneration in Example 1 Table 3 Structural properties before and after regeneration in Example 1

[0155]

[0156] Table 4 Catalytic evaluation results of Example 1

[0157]

[0158] III. Example 2

[0159] This embodiment uses lower micropore occupancy, peel strength, and addressant dosage; except for the following conditions, the rest of the operation is the same as in Example 1:

[0160] The amount of methyl ethyl ketone oxime added was 4% of the dry mass of the pretreated catalyst; the methyl ethyl ketone oxime was contacted with the catalyst at 25℃ for 2 h; the concentration of ammonium citrate was 0.030 mol / L; the pH of the stripping solution was 5.5; the liquid-to-solid ratio of the stripping solution to the catalyst was 5 mL / g; the stripping temperature was 45℃ for 1 h; the concentration of the addressing agent was 0.005 mol / L; the molar ratio of water to hydrolyzable alkoxy groups was 0.10:1; the addressing temperature was 40℃ for 2 h; the ratio of the amount of titanium added to the amount of fixed coordinated nitrogen was 0.20; the titanium capture temperature was 20℃ for 2 h; the alternating gas-solid solidification temperature was 90℃, and the partial pressure of water vapor was 3 kPa; a single water vapor contact was 1 min, followed by purging with dry nitrogen for 8 min, for a total of 5 cycles; the staged treatment temperatures were 200℃, 300℃, and 430℃ respectively.

[0161] These conditions are suitable for deactivated catalysts with significant organic blockage and relatively low non-framework titanium accumulation. The micropore volume of the regenerated catalyst was measured to be 0.161 cm³ / g, the cyclohexanone conversion rate was 94.8%, and the cyclohexanone oxime selectivity was 97.5%.

[0162] IV. Example 3

[0163] This embodiment employs a higher footprint, stripping strength, and addressing level; except for the following conditions, the remaining operations are the same as in Embodiment 1:

[0164] The amount of methyl ethyl ketone oxime added was 12% of the dry mass of the catalyst; the methyl ethyl ketone oxime was contacted at 50℃ for 6 h; the concentration of ammonium citrate was 0.15 mol / L; the pH of the stripping solution was 4.2; the liquid-to-solid ratio of the stripping solution to the catalyst was 12 mL / g; the stripping temperature was 65℃ for 3 h; the concentration of the addressing agent was 0.050 mol / L; the molar ratio of the addressing agent to the accessible silanol group was 0.40:1; the molar ratio of water to hydrolyzable alkoxy group was 0.40:1; the addressing temperature was 80℃ for 6 h; the ratio of the amount of titanium added to the amount of fixed coordinated nitrogen was 0.40; the titanium capture temperature was 45℃ for 6 h; the alternating gas-solid solidification temperature was 150℃, the partial pressure of water vapor was 20 kPa; the water vapor contact was 5 min, followed by purging with dry nitrogen for 20 min, for a total of 20 cycles; the staged treatment temperatures were 260℃, 380℃, and 480℃ respectively.

[0165] This embodiment is applicable to catalysts with significant accumulation of non-framework titanium-silicon species; the liquid phase silicon concentration should be monitored during the stripping process; when the silicon concentration continues to rise rapidly, the processing time should be shortened or the pH of the stripping solution should be increased.

[0166] The micropore volume of the obtained regenerated catalyst was found to be 0.158 cm³ / g, the cyclohexanone conversion rate was 95.9%, and the cyclohexanone oxime selectivity was 97.9%.

[0167] V. Example 4

[0168] This embodiment uses a diethylenetriamine type bissilane addressant, the structural formula of which is:

[0169] (EtO)3Si—(CH2)3—NH—CH2CH2—NH—CH2CH2—NH—(CH2)3—Si(OEt)3;

[0170] The addressing agent concentration was 0.015 mol / L, the molar ratio of water to hydrolyzable ethoxy groups was 0.15:1, and the pre-hydrolysis was carried out at 25℃ for 20 min; the addressing temperature was 65℃, and the treatment time was 4 h.

[0171] After addressing, the sample was washed twice with anhydrous ethanol containing 0.03% acetic acid, and then once with neutral anhydrous ethanol. The amount of titanium added was calculated based on the actual fixed coordinated nitrogen content after competitive washing. The ratio of the amount of titanium added to the amount of fixed coordinated nitrogen was 0.28.

[0172] The remaining operations were the same as in Example 1; the micropore volume of the obtained regenerated catalyst was 0.163 cm³ / g, the cyclohexanone conversion rate was 96.8%, and the cyclohexanone oxime selectivity was 98.2%.

[0173] VI. Example 5

[0174] In this embodiment, aminophosphonic acid chelating resin is used to recover endogenous titanium, and ethylene glycol is used as a titanium coordination stabilizer.

[0175] The pH of the extract was adjusted to 3.2 and passed through an activated aminophosphonic acid chelating resin; after washing with water, titanium was eluted with a 0.8 mol / L lactic acid aqueous solution.

[0176] The titanium eluent was converted into an isopropanol-water mixture with a water content of 10% and a Ti concentration of 0.015 mol / L. Ethylene glycol was added at a molar ratio of 3:1 to Ti, and the apparent pH was adjusted to 5.8.

[0177] Endogenous titanium was captured at a ratio of 0.30 between the amount of titanium added and the amount of fixed coordinated nitrogen, at a capture temperature of 35°C for 5 hours. After capture, the sample was washed twice with anhydrous isopropanol for 10 minutes each time.

[0178] The remaining operations were the same as in Example 1; the cyclohexanone conversion rate of the obtained regenerated catalyst was 96.9%, the cyclohexanone oxime selectivity was 98.1%, and the H2O2 utilization rate was 89.8%.

[0179] VII. Example 6

[0180] This embodiment uses a hydroxamic acid chelating resin and acetylacetone to stabilize the endogenous titanium.

[0181] The extract was adjusted to pH 3.8 and passed through a hydroxamic acid chelating resin; after washing with water, titanium was eluted with a 0.5 mol / L lactic acid aqueous solution.

[0182] The obtained titanium solution was converted into an ethanol-water system with a water content of 5% and a Ti concentration of 0.010 mol / L. Acetylacetone was added at a molar ratio of 0.5:1 to Ti, and the mixture was stirred at 30°C for 1 hour.

[0183] Titanium capture was performed at a ratio of 0.25 between the amount of titanium added and the amount of fixed coordinated nitrogen. After capture, the sample was washed twice with anhydrous ethanol containing 0.010 mol / L acetylacetone for 5 min each time.

[0184] The remaining operations were the same as in Example 1; the cyclohexanone conversion rate of the obtained regenerated catalyst was 96.4%, and the cyclohexanone oxime selectivity was 98.0%.

[0185] VIII. Example 7

[0186] In this embodiment, acetone oxime is used as a reversible microporous site-filling agent;

[0187] The amount of acetone oxime added was 6% of the dry weight of the pretreated catalyst, and the solvent was anhydrous ethanol. The acetone oxime was contacted with the catalyst at 30°C for 3 hours, filtered, and then treated under reduced pressure at 50°C.

[0188] The remaining stripping, addressing, endogenous titanium recovery, capture, and alternating gas-solid solidification treatments were the same as in Example 1. After the alternating gas-solid solidification treatment was completed, the mixture was washed three times with ethanol at 50°C and then treated in nitrogen containing 2% oxygen at 150°C for 1 hour to remove acetone oxime.

[0189] The micropore volume of the obtained regenerated catalyst was found to be 0.164 cm³ / g, the cyclohexanone conversion rate was 96.9%, and the cyclohexanone oxime selectivity was 98.2%.

[0190] IX. Example 8

[0191] In this embodiment, cyclohexanone oxime is used as a reversible microporous site-filling agent;

[0192] The amount of cyclohexanone oxime fed was 10% of the dry weight of the pretreated catalyst, and the solvent was tert-butanol. The cyclohexanone oxime was contacted with the catalyst at 45°C for 5 hours, filtered, and then subjected to vacuum treatment at 60°C.

[0193] The remaining operations are the same as in Example 1; since the diffusion rate of cyclohexanone oxime is relatively slow, the contact time should be appropriately extended, and its retention should be confirmed by thermogravimetric loss and micropore volume change.

[0194] The micropore volume of the obtained regenerated catalyst was found to be 0.160 cm³ / g, the cyclohexanone conversion rate was 95.7%, and the cyclohexanone oxime selectivity was 97.8%.

[0195] 10. Example 9

[0196] This embodiment illustrates the handling method when the amount of endogenous titanium recovered in the same batch is insufficient to meet the calculation of the feed amount;

[0197] Pretreatment, micropore filling, selective stripping, addressing, and competitive washing were completed according to Example 1; the required titanium addition was calculated to be 5.0 mmol based on the fixed coordination nitrogen content, and the actual titanium recovery from the same batch of extract was 4.2 mmol;

[0198] 4.2 mmol of endogenous titanium was mixed with 0.8 mmol of lactic acid-stabilized exogenous titanium to obtain a capture solution with a total titanium content of 5.0 mmol, of which 84 mol% was endogenous titanium from the same batch; the exogenous titanium stabilizing solution was prepared by adding tetraethyl titanate to a lactic acid-ethanol system, with a lactic acid to exogenous Ti molar ratio of 2:1.

[0199] The remaining capture, pre-washing before alternating gas-solid solidification, water vapor contact-drying gas purging alternating gas-solid solidification and staged oxidation operations are the same as in Example 1;

[0200] The test results showed that the cyclohexanone conversion rate of the obtained regenerated catalyst was 96.5%, the cyclohexanone oxime selectivity was 98.1%, and the H2O2 utilization rate was 89.7%.

[0201] XI. Detection Results of Different Embodiments

[0202]

[0203] Table 5. Structure and catalytic performance of different embodiments

[0204] Comparative Example

[0205] Comparative Example 1: No micropore placement

[0206] After the deactivated catalyst was pretreated, selective stripping was performed directly using the ammonium citrate solution from Example 1, with the remaining operations being the same as in Example 1.

[0207] The analysis showed that the amount of titanium in the extract was 7.60 mmol, accounting for 25.6% of the initial total titanium, which was higher than 18.8% in Example 1. The relative absorption area of ​​the 210-230 nm region in the exfoliated solid was lower than that in Example 1, indicating that more original titanium entered the exfoliation solution when no site was occupied.

[0208] Comparative Example 2: No defect addressing performed

[0209] After the stripped solid phase is replaced with solvent and dried, it is directly contacted with the stabilized endogenous titanium liquid; the amount of titanium added is calculated according to the mass of the catalyst to be the same as in Example 1, and the rest of the operation is the same as in Example 1.

[0210] After capture, the solid temporarily retained approximately 3.10 mmol of titanium. Before alternating gas-solid solidification, washing removed approximately 1.48 mmol of titanium, and finally, approximately 1.45 mmol of titanium was backfilled.

[0211] Comparative Example 3: Using a monosilane addressant

[0212] 3-Aminopropyltriethoxysilane was used instead of bissilane addressing agent, and the total nitrogen content of the addressing agent was basically the same as in Example 1;

[0213] After competitive washing, the mass fraction of fixed coordinated nitrogen was 0.15%, lower than 0.24% in Example 1; after curing, approximately 2.89 mmol of titanium was backfilled.

[0214] Comparative Example 4: Using a bissilane without coordinated nitrogen

[0215] 1,2-bis(triethoxysilyl)ethane is used instead of nitrogen-containing bissilane addressing agents; the compound has two hydrolyzable silane ends but does not contain coordinating nitrogen for capturing titanium;

[0216] The same amount of titanium was used as in Example 1; after washing before alternating gas-solid solidification, only about 1.10 mmol of backfill titanium was retained in the solid.

[0217] Comparative Example 5: No competing washing

[0218] After addressing treatment, instead of competitive washing with acidic anhydrous alcohol and neutral anhydrous alcohol, intrinsic titanium is added directly according to the amount of addressing agent added.

[0219] Since physical adsorption and liquid-phase oligomer addressants were not removed, approximately 7.0 mmol of titanium was added based on the total nitrogen content of the addressed solid without competitive washing correction; approximately 4.65 mmol of titanium was backfilled into the solid after curing, but the proportion of high-polymer titanium-related absorption increased.

[0220] Comparative Example 6: Washing before alternating vapor-solid curing

[0221] After the endogenous titanium was captured, it was not washed with anhydrous alcohol, but directly subjected to alternating gas-solid solidification treatment of water vapor contact and dry gas purging; the final backfill titanium was about 4.12 mmol, which was higher than that in Example 1, but the relative absorption area in the 320-350 nm region was significantly increased.

[0222] Comparative Example 7: Continuous high humidity treatment

[0223] The alternating gas-solid solidification process of water vapor contact-drying gas purging in Example 1 was replaced with continuous water vapor treatment; the treatment was carried out continuously for 150 min at 120°C and water vapor partial pressure of 10 kPa, and the remaining operations were the same as in Example 1.

[0224] Comparative Example 8: Remove the addressing agent first, then perform steam treatment.

[0225] After the endogenous titanium is captured and the washing is completed before alternating gas-solid solidification, the nitrogen-containing organic linker of the defect addressing agent is removed first according to the staged oxidation procedure of Example 1, and then steam treatment is performed.

[0226] The amount of backfilled titanium in the treated solid was approximately 2.76 mmol, lower than in Example 1.

[0227] Comparative Example 9: All titanium was sourced from external sources.

[0228] Lactic acid stabilized titanium solution was prepared using tetraethyl titanate. The Ti concentration and titanium feed amount were the same as in Example 1. All titanium used was exogenous titanium. The remaining operations were the same as in Example 1.

[0229] XII. Test Results of Examples and Comparative Examples

[0230] Table 6 Intermediate Process Data

[0231]

[0232] Table 7 Comparison of Structure and Catalytic Performance

[0233]

[0234] XIII. Evaluation of Reuse

[0235] After each reaction, the catalyst was washed three times with tert-butanol, dried under vacuum at 60°C, and then used for the next reaction; the results of repeated use are shown in Table 8.

[0236] Table 8 Results of catalyst reuse

[0237]

[0238] The above embodiments illustrate that micropore occupancy, selective stripping, bissilane defect addressing, metered addition of endogenous titanium according to fixed coordination nitrogen content, alternating gas-solid curing pre-washing, water vapor contact-drying gas purging alternating gas-solid curing, and removal of nitrogen-containing organic linker segments of defect addressing agent after Ti-O-Si connection formation can be continuously implemented in the same regeneration process; backfilled titanium does not need to be completely incorporated into the MFI crystal framework; backfilled titanium forms stable Ti-O-Si connections in the defect areas exposed after stripping, and forms four-coordinated titanium sites or framework-like titanium sites, thereby improving the cyclohexanone ammonium oxime performance, thus achieving the defect repair purpose of the present invention.

[0239] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A method for the synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst, characterized in that, Includes the following steps: (1) The deactivated TS-1 titanium-silicon molecular sieve catalyst derived from the cyclohexanone ammonium oximation reaction was washed with organic solvent and subjected to low-temperature oxidation treatment in an oxygen-containing atmosphere to obtain a pretreated catalyst. (2) Contact the pretreated catalyst with a solution containing a ketoxime reversible microporous site-occupying agent, and then remove the free solvent so that the ketoxime reversible microporous site-occupying agent is at least partially retained in the MFI channels of the pretreated catalyst that still maintain the microporous structure, and obtain a microporous site-occupying catalyst. (3) The microporous site-occupying catalyst is brought into contact with a selective stripping solution containing ammonium citrate, so that accessible non-framework titanium-silicon species can enter the liquid phase. After solid-liquid separation, a stripped solid phase A containing silicon hydroxyl defects and an extract containing endogenous titanium are obtained. (4) Solvent replacement of the stripped solid phase A is performed using alcohol or ketone solvents, followed by drying by vacuum drying, freeze drying or low-temperature fluidized bed drying to obtain the dried stripped solid phase A; (5) The dried stripped solid phase A is brought into contact with a defect addressing agent containing two hydrolyzable trialkoxysilane groups and an oxidizable organic linker containing a nitrogen-containing titanium ligand located between the two trialkoxysilane groups, so that the defect addressing agent is fixed to the silanol defect region of the stripped solid phase A through at least one silane end formed by the hydrolysis of the trialkoxysilane groups. (6) The solid obtained in step (5) is subjected to competitive washing with anhydrous alcohol or acid-containing anhydrous alcohol to remove the defect addressing agent that is not stably fixed in the silanol defect region, and the content of fixed coordinated nitrogen in the solid after competitive washing is determined. (7) Endogenous titanium was captured from extract B using chelating resin, and after washing, elution and coordination stabilization treatment, a stabilized endogenous titanium capture solution was obtained. (8) Determine the amount of stabilized endogenous titanium capture liquid added based on the fixed coordinated nitrogen content measured in step (6), so that the ratio of the amount of added titanium to the amount of fixed coordinated nitrogen is 0.20 to 0.40, and make the stabilized endogenous titanium capture liquid contact with the solid after competitive washing, so that the endogenous titanium coordinates with the nitrogen-containing titanium ligand and is captured. (9) Before performing the alternating gas-solid solidification treatment of water vapor contact-drying gas purging, the solid obtained in step (8) is washed with anhydrous alcohol or anhydrous alcohol containing titanium coordination stabilizer to remove titanium species not retained by the defect addressing agent. (10) At 90-150°C, the solid obtained in step (9) is subjected to alternating water vapor contact and dry gas purging by gas-solid contact method, and alternating gas-solid solidification treatment is carried out to allow the titanium captured by the defect addressing agent to undergo ligand exchange and limited hydrolysis, and form Ti-O-Si connection with the silanol defect region. (11) Remove the ketoxime reversible microporous site-occupying agent, and after the Ti-O-Si connection is formed, perform a staged oxidation treatment on the obtained solid to remove the nitrogen-containing organic linking segment of the defect addressing agent, and obtain the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst. In step (8), at least 80 mol% of the titanium added is derived from the extract B obtained in step (3); step (9) is performed before the water vapor contact in step (10); and in step (10), the solid is not immersed in the titanium-containing liquid phase.

2. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: In step (1), the organic solvent washing uses a mixture of tert-butanol and water, with a volume ratio of tert-butanol to water of 1:0.5 to 1:

3. The liquid-solid ratio of the mixture to the deactivated TS-1 titanium-silicon molecular sieve catalyst is 3 to 10 mL / g. The washing temperature is 40 to 70°C, and the washing time for a single wash is 1 to 3 h. The low-temperature oxidation treatment includes first treating at 160 to 200°C for 0.5 to 2 h in an atmosphere containing 1 to 10% oxygen by volume, and then treating at 240 to 290°C for 1 to 4 h.

3. The synergistic regeneration method for a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: In step (2), the ketoxime reversible microporous site-occupying agent is selected from one or more of acetone oxime, butanone oxime and cyclohexanone oxime, and the amount of ketoxime reversible microporous site-occupying agent fed is 4% to 12% of the dry basis mass of the pretreated catalyst; the pretreated catalyst and the ketoxime reversible microporous site-occupying agent are contacted at 25 to 50°C for 2 to 6 hours, and the free solvent is removed under reduced pressure at 40 to 70°C.

4. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: In step (3), the concentration of ammonium citrate in the selective stripping solution is 0.03-0.15 mol / L, the pH is 4.2-5.5, the liquid-solid ratio of the selective stripping solution to the microporous site-occupying catalyst is 5-12 mL / g, and the microporous site-occupying catalyst and the selective stripping solution are contacted at 45-65℃ for 1-3 h; in step (4), the stripping solid phase A is replaced with ethanol, isopropanol, tert-butanol or acetone 2-4 times.

5. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silica molecular sieve catalyst according to claim 1, characterized in that: In step (5), the defect addressing agent is N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine; the molar ratio of the defect addressing agent to the silanol groups in the stripped solid phase A is 0.05:1 to 0.40:1, and the molar ratio of water to the hydrolyzable alkoxy groups in the defect addressing agent is 0.1:1 to 0.4:1; after the defect addressing agent is pre-hydrolyzed in an alcohol solvent or toluene at 20 to 35°C for 10 to 60 min, it is contacted with the stripped solid phase A at 40 to 90°C for 1 to 8 h.

6. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: In step (6), anhydrous ethanol, anhydrous isopropanol, anhydrous ethanol containing 0.01-0.10% by mass acetic acid, or anhydrous isopropanol containing 0.01-0.10% by mass acetic acid are used for 1-4 competitive washings, each lasting 5-30 minutes. After washing with anhydrous ethanol containing acetic acid, the solid is washed at least once with anhydrous ethanol that does not contain acid. The mass fraction of fixed coordinated nitrogen in the solid after competitive washing is 0.05%-0.50%.

7. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: Step (7) includes: adjusting the pH of extract B to 2.8–4.2, passing extract B through an iminodiacetic acid chelating resin, an aminophosphonic acid chelating resin, or a hydroxamic acid chelating resin; washing the chelating resin that has captured endogenous titanium with deionized water; eluting titanium with a lactic acid aqueous solution with a concentration of 0.2–1.0 mol / L; adding lactic acid, ethylene glycol, or acetylacetone as a titanium coordination stabilizer to the obtained purified endogenous titanium solution, and converting the purified endogenous titanium solution into an ethanol-water mixture or an isopropanol-water mixture with a water mass fraction of 3%–15% to obtain a stabilized endogenous titanium capture solution with a titanium concentration of 0.005–0.03 mol / L and an apparent pH of 5.0–6.

5.

8. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: In step (8), the solid after competitive washing is mixed with the stabilized endogenous titanium capture solution at a solid-liquid ratio of 1:2 to 1:10 and contacted at 15 to 50°C for 1 to 8 hours; in step (9), anhydrous ethanol, anhydrous isopropanol, anhydrous ethanol containing 0.005 to 0.05 mol / L lactic acid, or anhydrous ethanol containing 0.005 to 0.02 mol / L acetylacetone are used for washing 1 to 3 times, with each washing lasting 2 to 15 minutes.

9. The method for synergistic regeneration of a cyclohexanone ammonoxime-deactivated titanium silicate molecular sieve catalyst according to claim 1, characterized in that: Step (10) is carried out at 110-130℃, with a water vapor partial pressure of 5-12 kPa, a single water vapor contact time of 1-5 min, a single dry gas purging time of 8-20 min, and water vapor contact and dry gas purging are alternated 8-12 times; after each water vapor contact, dry gas purging is performed, and the next water vapor contact begins after the water content of the outlet gas is reduced to a set value within the range of 500-2000 ppm. In step (11), the reversible microporous site-filling agent of ketoxime is first removed by washing with alcohol solvent and heat treatment in an oxygen atmosphere; then, the temperature is raised to 200-260℃ at 0.5-2℃ / min in an inert atmosphere and held for 1-3h, then raised to 300-380℃ at 0.5-1.5℃ / min in an atmosphere containing 1-3% by volume oxygen and held for 1-3h, and finally treated in air at 430-480℃ for 2-4h; all the titanium used to form Ti-O-Si linkages comes from the same batch of deactivated TS-1 titanium-silicon molecular sieve catalyst extract B, and the co-regeneration method does not add an independent external titanium source.

10. The application of the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst prepared by the synergistic regeneration method according to any one of claims 1 to 9 in the preparation of cyclohexanone oxime, characterized in that, Cyclohexanone, ammonia, and hydrogen peroxide are brought into contact in a liquid-phase reaction system containing the synergistically regenerated TS-1 titanium-silicon molecular sieve catalyst to carry out the cyclohexanone ammonium oxime reaction.

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