A recovery and regeneration method of a supported platinum-based catalyst for synthesizing KH-560

Abstract

The present application relates to the field of organic silicon material synthesis and industrial catalysis technology, in particular to a recycling method of a supported platinum-based catalyst for synthesis, the present application first removes polar adsorbents by low-carbon alcohol, then removes organic silicon oligomers and non-polar impurities by aromatic hydrocarbon, realizes channel dredging and surface cleaning; oxidizes and decomposes carbon deposition and residual organic matter at a mild temperature, at the same time, moderately oxidizes platinum into platinum dioxide, inhibits platinum particle migration and sintering, and prepares for subsequent reduction; reduces platinum dioxide into high-dispersion metallic Pt under a controllable hydrogen atmosphere 0 , reconfigures high-activity catalytic centers, and makes the activity close to the level of fresh catalyst. The whole process discards strong acid and strong base, and the solvent can be recycled, so as to realize green environmental protection and low waste discharge; at the same time, the process flow is mild and simple, and is suitable for the existing production line, so that the catalyst can be recycled for multiple times, and finally the precious metal unit consumption and production cost are significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon material synthesis and industrial catalysis technology, specifically relating to a method for recovering and regenerating a supported platinum-based catalyst used in hydrosilylation reactions, particularly suitable for γ-ray dihydrogen ionization (GDI) reactions. Glycidyl etheroxypropyltrimethoxysilane (KH) 560) Efficient regeneration, activity restoration and closed-loop recycling of deactivated platinum-carbon and platinum / alumina catalysts in industrial production. Background Technology

[0002] γ Glycidyl etheroxypropyltrimethoxysilane (trade code KH) KH560 is one of the most widely used and in-demand epoxy silane coupling agents, playing an irreplaceable role in industries such as composite materials, coatings, adhesives, electronic packaging, glass fiber treatment, and inorganic powder modification. With the rapid development of high-end manufacturing industries such as new energy, electronic information, and rail transportation, there is a growing demand for high-purity, low-impurity, and high-stability KH560. The continued growth in demand for 560 has placed higher demands on the economy, greenness, and continuous operation of its production processes.

[0003] Industrial KH 560 is mainly prepared by the hydrosilylation reaction of allyl glycidyl ether and trimethoxysilane. The core of this reaction is a highly efficient and selective platinum catalyst system. Traditional production processes mostly use homogeneous platinum catalysts, such as Speier and Karstedt catalysts, which have the advantages of high reactivity and mild conditions, but have obvious drawbacks: the catalyst is difficult to separate from the system and cannot be recycled; platinum metal residues are easily left in the product, affecting downstream applications; and the consumption and cost are high, which does not meet the requirements of modern green chemical industry.

[0004] To address these issues, the industry has gradually shifted towards supported heterogeneous platinum catalysts in recent years, such as platinum-carbon (Pt / C) and platinum / alumina (Pt / Al2O3). Heterogeneous catalysts can be easily separated through filtration and sedimentation, facilitating recovery and resulting in low metal residues, making them more suitable for continuous production. However, in actual industrial operation, supported platinum catalysts generally suffer from rapid deactivation, becoming a key bottleneck restricting their large-scale application.

[0005] The main causes of catalyst deactivation include: (1) Adsorption of organic matter and blockage of pores.

[0006] KH The 560 synthesis system contains a large number of organosilicon monomers, oligomers, by-products and unreacted raw materials. These substances are easily adsorbed on the surface and in the pores of the catalyst, covering the active sites and blocking the pores, which prevents the reactants from contacting the active centers and significantly reduces the catalytic efficiency.

[0007] (2) Carbon deposit formation and coverage.

[0008] At the reaction temperature, the adsorbed organic matter undergoes condensation, cross-linking, and carbonization, forming a dense carbon deposit layer that further isolates the active center, causing irreversible deactivation.

[0009] (3) Changes in the valence state of platinum active centers.

[0010] Highly active metallic Pt 0 During the reaction, it is easily oxidized or undergoes a valence state transition, forming low-activity or inactive Pt². + Pt 4+ The species leads to a significant reduction in catalytic ability.

[0011] (4) Platinum particle migration, agglomeration and sintering.

[0012] Long-term cycling and temperature fluctuations can cause platinum nanoparticles to migrate and grow, resulting in a decrease in specific surface area, a reduction in the number of active sites, and permanent inactivation.

[0013] If the deactivated platinum catalyst is discarded directly, it will result in a serious waste of precious platinum resources and a significant increase in KH. The production cost is 560 units; on the other hand, heavy metals and organic residues pose environmental risks, which is inconsistent with low-carbon, environmentally friendly, and sustainable development policies. Therefore, developing a mild, efficient, non-destructive catalyst regeneration technology with high activity recovery is crucial for advancing the development of heterogeneous platinum catalysts in KH. The industrial application of 560 in production is of great significance.

[0014] Existing regeneration technologies have significant shortcomings: Simple organic solvent washing can only remove a small amount of physical adsorbates, and cannot treat carbon deposits and valence state deactivation, resulting in limited activity recovery; Direct calcination at high temperatures can easily lead to severe sintering of platinum particles, collapse of the carrier structure, and further reduction in activity. Wet etching with strong acids, strong alkalis, and strong oxidants can damage the carrier, dissolve platinum metal, and produce wastewater with high salt, high COD, and high heavy metal content, posing a significant environmental challenge and making industrialization difficult.

[0015] Therefore, the industry urgently needs a mild, efficient, stable, environmentally friendly, and low-cost method for regenerating supported platinum catalysts to achieve closed-loop catalyst recycling, reduce production costs, and improve KH. The economic efficiency and competitiveness of 560 production. Summary of the Invention

[0016] The purpose of this invention is to provide a method for synthesizing KH A method for recovering and regenerating a supported platinum-based catalyst of 560, used in the synthesis of KH The method for recovering and regenerating the supported platinum-based catalyst of 560 solves the problem of KH mentioned in the background art. The supported platinum catalyst used in the synthesis of 560 has problems such as easy deactivation, difficult regeneration, low activity recovery rate, environmentally unfriendly process, and high cost.

[0017] To achieve the above objectives, the present invention provides the following technical solution: A method for synthesizing KH The method for recovering and regenerating the supported platinum-based catalyst of 560 includes the following steps: Step 1: Step solvent washing. The deactivated supported platinum catalyst after the hydrosilylation reaction is placed in a Soxhlet extractor and washed in a step reflux with low-carbon alcohol solvent and aromatic solvent in sequence. After filtration and drying, the pretreated catalyst is obtained. Step 2: Low-temperature oxidation and calcination. The pretreated catalyst is calcined at a low temperature in an oxygen-containing atmosphere. Step 3: Hydrogen reduction activation. The oxidized and calcined catalyst is reduced in a hydrogen or hydrogen-nitrogen mixed atmosphere to directionally reduce platinum dioxide to highly dispersed metallic Pt. 0 The active center is restored to catalytic activity, resulting in a regenerated catalyst.

[0018] Preferably, the low-carbon alcohol solvent in step one is one or more of methanol, ethanol, and isopropanol; the aromatic solvent is one or two of toluene and xylene.

[0019] Preferably, the mass ratio of catalyst to solvent in step one is 1:5–1:20.

[0020] Preferably, the washing time for a single segment in step one is 2–6 hours, and the washing temperature is the solvent reflux temperature.

[0021] Preferably, the drying temperature in step one is 60–140°C and the drying time is 4–12 hours.

[0022] Preferably, the oxidation and calcination atmosphere in step two is air.

[0023] Preferably, the calcination temperature in step two is 250–400℃; the calcination time is 2–5h; and the calcination heating rate is 2–5℃ / min.

[0024] Preferably, the reducing atmosphere in step three is a hydrogen-nitrogen mixed atmosphere, wherein the content of H2 is 5%–10% and the remainder is N2.

[0025] Preferably, the reduction temperature in step three is 300–400℃; the reduction time is 1–4h.

[0026] Preferably, the airspeed in step three is 50–500 h⁻¹. 1 The space velocity refers to the volumetric space velocity, which is the volume of mixed gas passing through a unit volume catalyst bed under standard conditions per unit time.

[0027] By means of the above technical solution, the present invention provides a method for synthesizing KH The recovery and regeneration method for the supported platinum-based catalyst of 560 has at least the following beneficial effects: This invention employs a combination of solvents with increasing polarity, first using low-carbon alcohols to elute polar adsorbates, and then using aromatics to deeply remove organosilicon oligomers and non-polar impurities, thereby achieving pore unblocking and surface cleaning. At a mild temperature, carbon deposits and residual organic matter are oxidized and decomposed, while platinum is moderately oxidized to platinum dioxide to inhibit the migration and sintering of platinum particles, thus preparing for subsequent reduction. Platinum dioxide was reduced to highly dispersed metallic Pt under a controlled hydrogen atmosphere. 0 This reconstructs highly active catalytic centers, bringing their activity close to that of fresh catalysts.

[0028] The entire process eliminates strong acids and alkalis, and the solvent is recyclable, thus achieving green environmental protection and low waste emissions. At the same time, the process is mild and simple, and is compatible with existing production lines, allowing the catalyst to be recycled multiple times, ultimately significantly reducing the consumption of precious metals and production costs. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] A method for synthesizing KH The method for recovering and regenerating the supported platinum-based catalyst of 560 includes the following steps: Step 1: Stepwise solvent washing The deactivated supported platinum catalyst after hydrosilylation reaction was placed in a Soxhlet extractor and washed in a stepwise reflux with low-carbon alcohol solvent and aromatic solvent to fully remove organic matter such as organosilicon oligomers, reactants, and byproducts adsorbed on the surface and in the pores. The catalyst was then filtered and dried to obtain the pretreated catalyst.

[0031] It should be noted that the solvent can be condensed, recovered, and recycled.

[0032] Step 2: Low-temperature oxidation and calcination The pretreated catalyst is calcined at low temperature in an oxygen-containing atmosphere to deeply remove residual carbon deposits and organic impurities, while oxidizing low-valence platinum to platinum dioxide to avoid sintering of platinum particles and destruction of the support structure caused by high temperature.

[0033] It should be noted that the oxidative calcination exhaust gas, after being treated by acid washing, SCR, and alkaline washing spray tower, can meet emission standards after simple dust removal treatment.

[0034] Step 3: Hydrogen reduction and activation The calcined catalyst was reduced in a hydrogen or hydrogen-nitrogen mixed atmosphere to directionally reduce platinum dioxide to highly dispersed metallic Pt. 0 The active center is restored to catalytic activity, resulting in a regenerated catalyst.

[0035] Example 1 The raw material is a deactivated Pt / C catalyst, sourced from industrial KH. 560 production facilities; The low-carbon alcohol solvent and aromatic solvent used are ethanol and toluene, both at industrial grade concentrations; The equipment includes a Soxhlet extractor, a tube furnace, an electronic balance, and a gas chromatograph.

[0036] Step 1, Stepwise solvent washing: Take 100g of deactivated Pt / C catalyst, place it in a Soxhlet extractor, add 1000g of ethanol, reflux and wash for 4h, filter; then add 1000g of toluene, reflux and wash for 4h, filter, and vacuum dry at 80℃ for 8h.

[0037] Step 2: Low-temperature oxidation and calcination: The dried catalyst was placed in a tube furnace and heated to 300°C at a rate of 3°C / min under air atmosphere, and calcined at a constant temperature for 3 hours.

[0038] Step 3: Hydrogen reduction and activation: A hydrogen-nitrogen mixture of 10% H2 and 90% N2 is introduced at a space velocity of 200 h⁻¹. - ¹, The temperature was 350℃, the reduction time was 2h, and the regenerated Pt / C catalyst was obtained by cooling.

[0039] The resulting regenerated Pt / C catalyst, under the same evaluation conditions, achieved a conversion rate of 99.0%, a selectivity of 98.3%, and a relative activity of 99.8%.

[0040] This example illustrates how the catalyst's catalytic performance can be almost completely recovered under these conditions.

[0041] Example 2 Differences from Example 1: The low-carbon alcohol solvent and aromatic solvent used were methanol + xylene, both at industrial grade concentrations. The catalyst to solvent mass ratio was 1:10, and the single-stage washing time was 4 hours.

[0042] The remaining steps are the same as in Example 1.

[0043] The resulting regenerated Pt / C catalyst, under the same evaluation conditions, achieved a conversion rate of 97.7%, a selectivity of 98.2%, and a relative activity of 98.5%.

[0044] This example illustrates that changing the cleaning solvent and using only aromatic solvents for gradient reflux washing will slightly reduce the catalyst's catalytic performance. Therefore, different solvent systems will have a slight impact on the catalyst's regeneration limit.

[0045] Example 3 The difference from Example 1 is as follows: The catalyst is deactivated Pt / C; In step two, the calcination temperature is 400℃, and the calcination is carried out at a constant temperature for 2 hours; The reduction temperature in step three is 400℃.

[0046] The remaining steps are the same.

[0047] The resulting regenerated Pt / C catalyst, under the same evaluation conditions, achieved a conversion rate of 97.3%, a selectivity of 97.9%, and a relative activity of 98.0%. Examples illustrate that high temperatures are not suitable for the regeneration of carbon-based Pt / C catalysts.

[0048] It should be noted that there is a slight risk of ablation on activated carbon carriers at 400℃, therefore this temperature environment is only suitable for non-carbon carriers or short-term treatment.

[0049] It should be noted that there is a slight risk of ablation on activated carbon carriers at 400℃, therefore this temperature environment is only suitable for non-carbon carriers or short-term treatment.

[0050] Example 4 The difference from Example 1 is as follows: In step three, the reducing atmosphere is 5% H2 and 95% N2, the reduction temperature is 300℃, and the space velocity is 100 h⁻¹. - ¹, Restoration time 3 hours.

[0051] The remaining steps are the same.

[0052] The resulting regenerated Pt / C catalyst, under the same evaluation conditions, achieved a conversion rate of 98.8%, a selectivity of 98.1%, and a relative activity of 99.6%.

[0053] The example illustrates that efficient catalyst regeneration can still be achieved using a lower hydrogen concentration, almost completely restoring the catalyst's catalytic performance.

[0054] Example 5 The difference from Example 1 is that the calcination temperature in step 2 is 250°C, and the calcination is carried out at a constant temperature for 3 hours; the reduction temperature in step 3 is 350°C.

[0055] The remaining steps are the same.

[0056] The resulting regenerated Pt / C catalyst, under the same evaluation conditions, achieved a conversion rate of 98.8%, a selectivity of 98.2%, and a relative activity of 99.6%.

[0057] Comparing Examples 1 to 5, it is evident that increasing the calcination temperature is beneficial for in-depth removal of carbon deposits, but the temperature should not be too high. Calcination at 250℃ (Example 5) resulted in incomplete carbon removal, with a relative activity of 99.6%. Calcination at 300℃ (Example 1) completely removed carbon deposits, achieving optimal activity recovery (99.8%). Increasing the temperature to 400℃ (Example 3) triggered the risk of precious metal agglomeration and carbon support ablation, causing the relative activity to decline to 98.5%. Therefore, the optimal calcination temperature for Pt / C catalyst regeneration is around 300℃, and should not be lower than 250℃ or higher than 400℃.

[0058] Comparative Example 1 The deactivated Pt / C catalyst was directly evaluated by washing with ethanol without calcination or reduction.

[0059] The relative activity of the catalyst is only 79.5% of that of the fresh catalyst.

[0060] Comparative Example 2 The deactivated catalyst was directly calcined in air at 550°C without washing.

[0061] Due to high-temperature sintering, the relative activity of the catalyst is only 73.5%.

[0062] Activity evaluation results and analysis Evaluation criteria: Allyl glycidyl ether:trimethoxysilane = 1:1.05 (molar ratio), catalyst dosage 0.1wt%, reaction temperature 80℃, time 4h. The results are shown in Table 1: Table 1. Relative Catalyst Activity under Different Regeneration Processes Please refer to Table 1. By comparing Examples 1 to 5, Comparative Example 1, and Comparative Example 2, the regeneration process of the present invention can efficiently restore catalyst activity, so that the catalyst activity is restored to more than 95%.

[0063] Example 6 Differences from Example 1: The regenerated catalyst from Example 1 was reused in KH The 560 synthesis reaction was followed by deactivation, and the regeneration process of Example 1 of this invention was repeated for 5 consecutive cycles.

[0064] The results show: First regeneration: Catalyst relative activity 99.6% Third regeneration: Catalyst relative activity 98.5% Fifth regeneration: Catalyst relative activity 97.8% The relative activity of the catalysts remained above 95%, and the cycle stability was excellent.

[0065] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing KH The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, Includes the following steps: Step 1: Step solvent washing. The deactivated supported platinum catalyst after the hydrosilylation reaction is placed in a Soxhlet extractor and washed in a step reflux with low-carbon alcohol solvent and aromatic solvent in sequence. After filtration and drying, the pretreated catalyst is obtained. Step 2: Low-temperature oxidation and calcination. The pretreated catalyst is calcined at a low temperature in an oxygen-containing atmosphere. Step 3: Hydrogen reduction activation. The oxidized and calcined catalyst is reduced in a hydrogen or hydrogen-nitrogen mixed atmosphere to directionally reduce platinum dioxide to highly dispersed metallic Pt. 0 The active center is restored to catalytic activity, resulting in a regenerated catalyst.

2. The method for synthesizing KH according to claim 1 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The low-carbon alcohol solvent mentioned in step one is one or more of methanol, ethanol, and isopropanol; the aromatic solvent is one or two of toluene and xylene.

3. A method for synthesizing KH according to claim 2 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The mass ratio of catalyst to solvent in step one is 1:5–1:

20.

4. A method for synthesizing KH according to claim 3 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, In step one, the washing time for a single segment is 2–6 hours, and the washing temperature is the solvent reflux temperature.

5. A method for synthesizing KH according to claim 4 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The drying temperature in step one is 60–140℃, and the drying time is 4–12h.

6. A method for synthesizing KH according to claim 1 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The oxidation and calcination atmosphere in step two is air.

7. A method for synthesizing KH according to claim 6 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The calcination temperature in step two is 250–400℃; the calcination time is 2–5h; and the calcination heating rate is 2–5℃ / min.

8. A method for synthesizing KH according to claim 1 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The reducing atmosphere described in step three is a hydrogen-nitrogen mixed atmosphere, wherein the content of H2 is 5%–10% and the remainder is N2.

9. A method for synthesizing KH according to claim 8 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The reduction temperature in step three is 300–400℃; the reduction time is 1–4h.

10. A method for synthesizing KH according to claim 9 The method for recovering and regenerating the supported platinum-based catalyst of 560 is characterized in that, The airspeed mentioned in step three is 50–500 h. 1 The space velocity refers to the volumetric space velocity, which is the volume of mixed gas passing through a unit volume catalyst bed under standard conditions per unit time.

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