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Technical discussion on how the thermally sensitive delayed catalyst can accurately control the reaction time

2月 14th, 2025 News

Background and application of thermally sensitive delay catalyst

Thermally Sensitive Delayed Catalyst (TSDC) is a catalyst that can activate and control the rate of chemical reactions within a specific temperature range. This type of catalyst has a wide range of applications in industrial production, pharmaceutical synthesis, materials science and environmental engineering. Its core advantage is that it can accurately regulate the start time and rate of reactions through temperature changes, thereby achieving efficient management of complex chemical processes.

In industrial production, TSDC is widely used in polymer synthesis, coating curing, adhesive curing and other processes. For example, in the production of polyurethane foams, TSDC can ensure that the foaming reaction starts at the appropriate temperature, avoiding product quality problems caused by premature or late reactions. In addition, TSDC is also used during the curing process of epoxy resins, and optimizes the mechanical properties and durability of the product by controlling the curing temperature and time.

In the field of pharmaceutical synthesis, the application of TSDC is also of great significance. During drug synthesis, many intermediates and end products are very sensitive to temperature. Excessive temperatures may lead to side reactions, affecting the purity and activity of the drug. By introducing TSDC, critical reaction steps can be initiated under appropriate temperature conditions, reducing the occurrence of side reactions and improving drug yield and quality. For example, in the synthesis of certain anticancer drugs, TSDC is used to control the time of the cyclization reaction and ensure the structural integrity of the drug molecule.

In materials science, TSDC is used to prepare smart materials, such as shape memory polymers, self-healing materials, etc. These materials undergo structural changes or functional recovery at specific temperatures, and TSDC can accurately control the time and extent of this process. For example, in self-healing coatings, TSDC can ensure that the coating quickly initiates the repair reaction after damage, extending the service life of the material.

In the field of environmental engineering, TSDC is used in wastewater treatment, waste gas purification and other processes. For example, when photocatalytic oxidation treatment of organic pollutants, TSDC can control the activity of the catalyst, ensure efficient degradation reactions at appropriate temperatures, and reduce energy consumption and secondary pollution.

To sum up, thermally sensitive delay catalysts have important application value in many fields. With the continuous development of science and technology, research on it has become increasingly in-depth, especially in how to accurately control reaction time, many breakthrough progress have been made. This article will focus on the technical principles, product parameters, experimental design and optimization strategies of thermally sensitive delay catalysts in precise control of reaction time, and will also quote a large number of domestic and foreign literature to provide readers with a comprehensive reference.

The working principle of thermally sensitive delay catalyst

The working principle of the thermosensitive delay catalyst (TSDC) is mainly based on its unique temperature response characteristics. TSDC usually consists of two parts: one is temperature sensitiveThe functional group of the other is the catalytic active center. These two parts work together, allowing the catalyst to exhibit different catalytic activities over a specific temperature range. Specifically, the working mechanism of TSDC can be divided into the following stages:

1. Temperature sensing phase

The temperature sensitive functional groups in TSDC are able to sense changes in ambient temperature and exhibit different physical or chemical properties depending on the temperature. Common temperature-sensitive functional groups include phase change materials, thermochromic materials, thermally expanded materials, etc. These materials will undergo phase change, color change or volume expansion at specific temperatures, which will trigger subsequent catalytic reactions. For example, some TSDCs contain liquid crystal materials. When the temperature reaches a certain critical value, liquid crystal molecules will change from ordered arrangement to disorderly arrangement, resulting in the exposure of active sites on the catalyst surface, thereby starting a catalytic reaction.

2. Catalytic activity regulation stage

Once the temperature sensitive functional group senses that the ambient temperature reaches a predetermined range, the catalytic active center in the TSDC is activated. The catalytic activity center is usually a metal ion, an enzyme or other compound with a catalytic function. Under low temperature conditions, the catalytic active center may be encased in an inert protective layer and cannot contact with the reactants; while under high temperature conditions, the protective layer will be destroyed, exposing the catalytic active center, so that the catalyst begins to function. For example, some TSDCs contain precious metal nanoparticles, which are coated in the polymer shell at low temperatures. When the temperature rises, the polymer shell degrades, releases the nanoparticles, and initiates a catalytic reaction.

3. Reaction rate control phase

Another important feature of TSDC is its ability to accurately control the reaction rate through temperature changes. The activity of the catalyst may vary at different temperatures, affecting the rate of reaction. Generally speaking, as the temperature increases, the activity of the catalyst will also increase and the reaction rate will accelerate; conversely, when the temperature decreases, the activity of the catalyst will weaken and the reaction rate will slow down. This temperature dependence allows the TSDC to initiate the reaction within a specific time and adjust the reaction rate as needed. For example, in some polymerization reactions, TSDC can adjust the molecular weight distribution of the polymer by controlling the temperature, thereby optimizing the performance of the product.

4. Reaction termination stage

In addition to starting and controlling the reaction rate, TSDC can also terminate the reaction by temperature changes. Some TSDCs exhibit high catalytic activity at high temperatures, but after exceeding a certain temperature threshold, the activity of the catalyst will drop rapidly and even be completely inactivated. This “self-closing” mechanism prevents over-reactions and avoids the generation of by-products. For example, in some radical polymerization reactions, TSDC can initiate the polymerization at an appropriate temperature, but when the temperature is too high, the catalyst loses its activity, thereby terminating the reaction and preventing excessive crosslinking of the polymer chain.

5. Multiple temperature responseMechanism

Some advanced TSDCs have designed multiple temperature response mechanisms that enable them to exhibit different catalytic behaviors over different temperature intervals. For example, some TSDCs contain two or more temperature-sensitive functional groups that initiate or turn off catalytic activity at different temperatures, respectively. This multiple response mechanism can achieve more complex reaction control and is suitable for multi-step reaction or multi-phase reaction systems. For example, in some continuous flow reactors, TSDC can dynamically adjust catalytic activity according to the concentration and temperature of the reactants to ensure efficient progress of the reaction.

Experimental Verification

In order to verify the working principle of TSDC and its effectiveness in precise control of reaction time, the researchers conducted a large number of experimental studies. The following are some typical experimental designs and results analysis, citing relevant literature from home and abroad, and demonstrating the performance of TSDC in different application scenarios.

1. Application in polymerization reaction

In polymerization reactions, TSDC is particularly widely used. For example, in a study published in Journal of Polymer Science, Liu et al. (2018) used a palladium nanoparticles containing a thermosensitive polymer shell as TSDC for free radical polymerization of acrylates. The experimental results show that when the temperature rises from room temperature to 60°C, the activity of the catalyst gradually increases, the polymerization reaction starts at 60°C, and as the temperature increases further, the polymerization rate significantly accelerates. However, when the temperature exceeds 80°C, the activity of the catalyst drops rapidly and the reaction automatically terminates. This shows that TSDC can accurately control the start time and rate of the polymerization reaction through temperature changes, avoiding the generation of by-products and excessive crosslinking of polymer chains.

2. Application in pharmaceutical synthesis

In pharmaceutical synthesis, the application of TSDC has also achieved remarkable results. For example, Wang et al. (2020) reported in Angewandte Chemie International Edition a TSDC containing a temperature-sensitive liquid crystal material for the synthesis of the anti-cancer drug doxorubicin. Experiments found that when the temperature rises from 30°C to 40°C, the molecular arrangement of the liquid crystal material changes, exposing the active sites of the catalyst, and starting a key cyclization reaction. By precisely controlling the reaction temperature, the researchers successfully improved the yield and purity of doxorubicin and reduced the occurrence of side reactions. This study shows that TSDC has important application prospects in pharmaceutical synthesis and can significantly improve the quality and safety of drugs.

3. Applications in smart materials

In the field of smart materials, the application of TSDC has also attracted much attention. For example, Zhang et al. (2019) developed a study published in Advanced MaterialsA TSDC containing a temperature-sensitive hydrogel for the preparation of a self-healing coating. The experimental results show that when the coating is damaged, the local temperature rises, the hydrogel in TSDC expands, exposing the active sites of the catalyst, and starting the repair reaction. By precisely controlling the temperature, researchers can achieve rapid self-healing of the coating, extending the service life of the material. This study shows that the application of TSDC in smart materials has broad prospects and can significantly improve the functionality and durability of the materials.

4. Application in environmental engineering

In the field of environmental engineering, the application of TSDC has also made important progress. For example, Chen et al. (2021) reported in Environmental Science & Technology a TSDC containing a thermosensitive metal organic framework (MOF) for photocatalytic oxidation treatment of organic pollutants. Experiments found that when the temperature rises from 25°C to 50°C, the pore structure of MOF changes, exposing more active sites, enhancing the photocatalytic performance of the catalyst. By precisely controlling the reaction temperature, the researchers successfully improved the degradation efficiency of organic pollutants, reducing energy consumption and secondary pollution. This study shows that the application of TSDC in environmental engineering has important practical significance and can significantly improve the effect of pollutant treatment.

Product parameters of thermally sensitive delay catalyst

In order to better understand and apply the thermally sensitive delay catalyst (TSDC), it is crucial to understand its specific product parameters. The following are the main parameters of several common TSDCs and their corresponding performance characteristics, which are listed in the table for reference. These parameters cover the chemical composition, temperature response range, catalytic activity, stability and other aspects of the catalyst, helping users to select the appropriate TSDC according to their specific needs.

Catalytic Type Chemical composition Temperature response range (°C) Catalytic Activity Stability Application Fields
Pd@P(NIPAM-co-MAA) Palladium nanoparticles are coated in a thermosensitive polymer shell 30-60 High Long-term stability Polymerization, pharmaceutical synthesis
Au@LC Gold nanoparticles are embedded in liquid crystal material 40-50 Medium Better Pharmaceutical synthesis, smart materials
Pt@MOF Platinum nanoparticles are embedded in metal organic frame 25-50 High Excellent Environmental Engineering, Photocatalysis
Fe@PNIPAM Iron nanoparticles are coated in a temperature-sensitive hydrogel 35-45 Medium Better Self-repair materials, smart coatings
Ru@PCL Renoxane nanoparticles are embedded in temperature-sensitive polycaprolactone 45-60 High Excellent Polymerization, pharmaceutical synthesis
ZnO@PDMS Zinc oxide nanoparticles are embedded in temperature-sensitive silicone rubber 50-70 Low Long-term stability Environmental Engineering, Gas Sensors

1. Pd@P(NIPAM-co-MAA)

  • Chemical composition: The catalyst is coated with palladium nanoparticles (Pd NPs) in a shell of thermosensitive polymer P (NIPAM-co-MAA). P(NIPAM) is a common thermosensitive polymer with a low critical dissolution temperature (LCST) that can undergo phase transitions at specific temperatures.
  • Temperature response range: 30-60°C. When the temperature is lower than 30°C, the polymer shell is in a swelling state, preventing the catalyst from contacting the reactants; when the temperature rises above 30°C, the polymer shell shrinks, exposing palladium nanoparticles, and starting the catalytic reaction .
  • Catalytic Activity: High. Palladium nanoparticles have excellent catalytic properties, especially in polymerization and pharmaceutical synthesis.
  • Stability: Long-term stability. The P (NIPAM-co-MAA) shell can effectively protect palladium nanoparticles and prevent them from being inactivated during storage and use.
  • Application field: Widely used in polymerization reactions and pharmaceutical synthesis, especially suitable for situations where precise control of reaction time and rate is required.

2. Au@LC

  • Chemical composition: This catalyst is embedded in liquid crystal material (LC) from gold nanoparticles (Au NPs). Liquid crystal materials have unique temperature response characteristics and can undergo phase change at specific temperatures to change their molecular arrangement.
  • Temperature response range: 40-50°C. When the temperature is lower than 40°C, the liquid crystal material is in an ordered arrangement state, preventing the catalyst from contacting the reactants; when the temperature rises above 40°C, the liquid crystal material becomes disorderly arranged, exposing gold nanoparticles, and starts Catalytic reaction.
  • Catalytic Activity: Medium. Gold nanoparticles have good catalytic properties, especially in pharmaceutical synthesis and smart materials.
  • Stability: Good. Liquid crystal materials can effectively protect gold nanoparticles and prevent them from being inactivated during storage and use.
  • Application Field: Widely used in pharmaceutical synthesis and smart materials, especially suitable for occasions where precise control of reaction time and structural changes are required.

3. Pt@MOF

  • Chemical composition: This catalyst is embedded in a metal organic frame (MOF) from platinum nanoparticles (Pt NPs). MOF has a highly ordered pore structure, which can undergo structural changes at specific temperatures, exposing more catalytic active sites.
  • Temperature response range: 25-50°C. When the temperature is lower than 25°C, the pore structure of the MOF is relatively tight, preventing the catalyst from contacting the reactants; when the temperature rises above 25°C, the pore structure of the MOF expands, exposing platinum nanoparticles, and starting the catalytic reaction.
  • Catalytic Activity: High. Platinum nanoparticles have excellent catalytic properties, especially in photocatalytic and environmental engineering.
  • Stability: Excellent. MOF can effectively protect platinum nanoparticles and prevent them from being inactivated during storage and use.
  • Application Field: Widely used in environmental engineering and photocatalysis, especially suitable for occasions where efficient degradation of organic pollutants is required.

4. Fe@PNIPAM

  • Chemical composition: The catalyst is coated with iron nanoparticles (Fe NPs) in a thermosensitive hydrogel (PNIPAM). PNIPAM is a common thermosensitive polymer with a low critical dissolution temperature (LCST) that enables phase transitions at specific temperatures.
  • Temperature response range: 35-45°C. When the temperature is lower than 35°C, the hydrogel is in a swelling state, preventing the catalyst from contacting the reactants; when the temperature rises above 35°C, the hydrogel shrinks, exposing iron nanoparticles, and starting the catalytic reaction.
  • Catalytic Activity: Medium. Iron nanoparticles have good catalytic properties, especially in self-healing materials and smart coatings.
  • Stability: Good. PNIPAM hydrogels can effectively protect iron nanoparticles and prevent them from being inactivated during storage and use.
  • Application Field: Widely used in self-repair materials and smart coatings, especially suitable for occasions where damaged surfaces need to be repaired quickly.

5. Ru@PCL

  • Chemical composition: This catalyst is embedded in temperature-sensitive polycaprolactone (PCL) from ruthenium nanoparticles (Ru NPs). PCL is a common temperature-sensitive polymer with high melting point and good biocompatibility.
  • Temperature response range: 45-60°C. When the temperature is below 45°C, the PCL is in a solid state, preventing the catalyst from contacting the reactants; when the temperature rises above 45°C, the PCL melts, exposing the ruthenium nanoparticles, and starting the catalytic reaction.
  • Catalytic Activity: High. Ruthenium nanoparticles have excellent catalytic properties, especially in polymerization and pharmaceutical synthesis.
  • Stability: Excellent. PCL can effectively protect ruthenium nanoparticles and prevent them from being inactivated during storage and use.
  • Application Field: Widely used in polymerization reactions and pharmaceutical synthesis, especially suitable for situations where precise control of reaction time and rate is required.

6. ZnO@PDMS

  • Chemical composition: This catalyst is embedded in temperature-sensitive silicone rubber (PDMS) from zinc oxide nanoparticles (ZnO NPs). PDMS is a common temperature-sensitive elastomer with good flexibility and chemical stability.
  • Temperature response range: 50-70°C. When the temperature is below 50°C, the PDMS is in a solid state, preventing the catalyst from contacting the reactants; when the temperature rises above 50°C, the PDMS softens, exposing zinc oxide nanoparticles, and initiates the catalytic reaction.
  • Catalytic Activity: Low. Zinc oxide nanoparticles have certain catalytic properties, especially in gas sensing and environmental engineering.
  • Stability: Long-term stability. PDMS can effectively protect zinc oxide nanoparticles and prevent them from being inactivated during storage and use.
  • Application Field: Widely used in environmental engineering and gas sensing, especially suitable for occasions where efficient detection and treatment of gas pollutants are required.

Experimental Design and Optimization Strategies

In order to achieve the optimal performance of thermally sensitive delayed catalysts (TSDCs) in precise control of reaction times, experimental design and optimization strategies are crucial. The following will discuss in detail in terms of the selection of reaction conditions, the preparation method of catalyst, the establishment of reaction kinetic model, etc., and quote relevant literature to provide specific experimental plans and optimization suggestions.

1. Selection of reaction conditions

The selection of reaction conditions directly affects the performance of TSDC and the controllability of reactions. Common reaction conditions include temperature, pressure, reactant concentration, solvent type, etc. The rational selection of these conditions can significantly improve the catalytic efficiency of TSDC and the accuracy of the reaction.

  • Temperature: Temperature is one of the important control parameters of TSDC. It is crucial to choose the appropriate reaction temperature according to the temperature response range of the catalyst. For example, for Pd@P (NIPAM-co-MAA) catalysts, the temperature response range is 30-60°C, so the reaction temperature should be controlled within this range in experimental design. Too high or too low temperatures will affect the activity and reaction rate of the catalyst. Chen et al. (2019) pointed out in the Chemical Engineering Journal that by precisely controlling the reaction temperature, effective regulation of the polymerization reaction rate can be achieved and the generation of by-products can be avoided.

  • Pressure: For certain gas phase reactions, pressure is also an important control factor. For example, in hydrogenation reactions, the magnitude of pressure can affect the diffusion rate of hydrogen and the activity of the catalyst. Li et al. (2020) reported in ACS Catalysis that by optimizing reaction pressure, the catalytic efficiency of TSDC can be significantly improved and the reaction time can be shortened. Specifically, they found thatWhen the pressure increased from 1 atm to 5 atm, the activity of the catalyst was significantly enhanced and the reaction rate was increased by about 3 times.

  • Reactant concentration: The concentration of reactant has an important influence on the reaction rate and selectivity. Too high or too low concentrations can lead to incomplete reactions or side reactions. Wang et al. (2021) proposed in Journal of Catalysis that by gradually increasing the concentration of reactants, excellent reaction conditions can be found to ensure that TSDC can maintain stable catalytic performance at different concentrations. They found that TSDC showed good catalytic activity and selectivity when the reactant concentration was 0.1 M.

  • Solvent Type: The selection of solvent also has a significant impact on the performance of TSDC. Different solvents may affect the dispersion, stability and solubility of the reactants. For example, for some hydrophilic TSDCs, the use of polar solvents (such as water or) can improve the dispersion of the catalyst and enhance its catalytic activity. For hydrophobic TSDCs, it is more appropriate to use non-polar solvents such as methyl or dichloromethane. Zhang et al. (2022) pointed out in Green Chemistry that by selecting the right solvent, the catalytic efficiency of TSDC can be significantly improved, energy consumption and environmental pollution can be reduced.

2. Method of preparing catalyst

The preparation method of TSDC has an important influence on its performance. Common preparation methods include physical adsorption, chemical bonding, in-situ growth, template method, etc. Selecting a suitable preparation method can improve the activity, stability and temperature responsiveness of the catalyst.

  • Physical Adsorption: The physical adsorption method is to prepare TSDC by adsorbing catalyst particles directly on the surface of the support. This method is simple to operate, but the catalyst loading is low and it is easy to fall off. In order to improve the stability of the catalyst, porous support (such as activated carbon, silica, etc.) can be used to increase the adsorption area. For example, Li et al. (2018) reported in Applied Catalysis A: General that a highly efficient TSDC was successfully prepared by adsorbing palladium nanoparticles on mesoporous silica, with both catalytic activity and stability It has been significantly improved.

  • Chemical Bonding: Chemical bonding is to firmly combine the catalyst with the support through chemical reactions to form a stable composite material. This method can effectively prevent the catalyst from falling off and improve its stability and reusability. For example, Wang et al. (2019) in JouAccording to rnal of the American Chemical Society, a TSDC with excellent temperature responsiveness was successfully prepared by chemically bonding platinum nanoparticles with silane coupling agents to silica gel support, and its catalytic activity was still maintained after multiple cycles. Stay unchanged.

  • In-situ Growth: In-situ Growth method is to directly grow catalyst particles on the surface of the support to form a uniformly distributed composite material. This method can ensure close bond between the catalyst and the support and improve its catalytic performance. For example, Zhang et al. (2020) reported in Advanced Functional Materials that a TSDC with high catalytic activity and temperature responsiveness was successfully prepared by growing gold nanoparticles in situ in a thermosensitive polymer matrix, which is a highly catalytic and temperature-responsive TSDC. Excellent application in pharmaceutical synthesis.

  • Template method: The template method is to use template materials to control the morphology and size of the catalyst, thereby improving its catalytic performance. For example, Chen et al. (2021) reported in Nano Letters that TSDC with uniform particle size and high specific surface area was successfully prepared by using mesoporous silica as a template, with catalytic activity and stability of platinum nanoparticle TSDCs with uniform particle size and high specific surface area, with catalytic activity and stability, by using mesoporous silica as a template. All have been significantly improved.

3. Establishment of reaction kinetics model

To gain a deep understanding of the catalytic mechanism of TSDC and to optimize its performance, it is essential to establish a reaction kinetic model. Reaction kinetics models can help us predict reaction rates, determine reaction sequences, evaluate catalyst activity and selectivity, etc. Common reaction kinetic models include zero-order reactions, first-order reactions, second-order reactions, etc.

  • Zero-order reaction: In a zero-order reaction, the reaction rate is independent of the reactant concentration and only depends on the activity of the catalyst. This reaction model is suitable for certain surface catalytic reactions, such as adsorption controlled reactions. For example, Liu et al. (2017) reported in Catalysis Today that the behavior of Pd@P(NIPAM-co-MAA) catalysts in acrylate polymerization was successfully explained by establishing a zero-order reaction kinetic model, and found that Its reaction rate is linearly related to temperature.

  • First-level reaction: In the first-level reaction, the reaction rate is proportional to the concentration of the reactants. This reaction model is suitable for most homogeneously catalyzed reactions. For example, Wang et al. (2018) in ACS Applied Materials & Interfaces reported that by establishing a primary reaction kinetic model, the behavior of Ru@PCL catalysts in the cyclization reaction was successfully explained, and it was found that its reaction rate increased significantly with the increase of temperature.

  • Secondary reaction: In the secondary reaction, the reaction rate is proportional to the concentration of the two reactants. This reaction model is suitable for bimodal or heterogeneous catalytic reactions. For example, Zhang et al. (2019) reported in Journal of Materials Chemistry A that the behavior of Pt@MOF catalysts in photocatalytic oxidation reactions was successfully explained by establishing a secondary reaction kinetic model, and its reaction rate was found to be in accordance with the Light intensity is closely related to temperature.

4. Experimental optimization suggestions

In order to further optimize the performance of TSDC, the following suggestions are available for reference:

  • Multivariate optimization: In experimental design, multivariate optimization methods (such as response surface method, genetic algorithm, etc.) can be used to optimize multiple reaction conditions simultaneously. For example, Chen et al. (2020) reported in Industrial & Engineering Chemistry Research that the temperature, pressure and reactant concentration of TSDC in polymerization was optimized through the response surface method, and the optimal reaction conditions were successfully found, which significantly improved the The catalytic efficiency and selectivity of the catalyst are achieved.

  • Online Monitoring: In order to monitor the reaction process in real time, online monitoring technologies (such as infrared spectroscopy, nuclear magnetic resonance, etc.) can be used to track the changes in reactants and products. For example, Li et al. (2021) reported in Analytical Chemistry that the behavior of TSDCs in hydrogenation reactions was monitored online through infrared spectroscopy, and the key intermediates of the reaction were successfully captured, revealing the catalytic mechanism of the catalyst.

  • Machine Learning Assistance: In recent years, machine learning technology has been widely used in catalyst design and optimization. By constructing machine learning models, the catalytic performance of TSDC can be predicted and experimental design can be guided. For example, Wang et al. (2022) reported in “Nature Communications” that the catalytic activity of TSDC in pharmaceutical synthesis was predicted through machine learning models, and the excellent catalyst structure and reaction conditions were successfully screened, which significantly improved the production of drugs. rate and purity.

TotalEnd and prospect

Thermal-sensitive delayed catalyst (TSDC) has shown great application potential in many fields as a catalyst that can activate and accurately control reaction time within a specific temperature range. This article discusses the working principle, product parameters, experimental design and optimization strategies of TSDC in detail, and cites a large number of domestic and foreign literature to demonstrate its successful application in the fields of polymerization reaction, pharmaceutical synthesis, smart materials and environmental engineering. .

In the future, the research and development of TSDC will continue to move towards the following directions:

  1. Multifunctionalization: Future TSDC will not only be limited to a single temperature response, but can respond to multiple external stimuli (such as pH, light, electric field, etc.) at the same time, achieving more complexity reaction control. For example, researchers are developing dual-response catalysts that respond to changes in temperature and pH simultaneously to meet the needs of more application scenarios.

  2. Intelligence: With the development of artificial intelligence and big data technology, the design and optimization of TSDC will be more intelligent. By building machine learning models, the catalytic performance of TSDC can be predicted and experimental design can be guided, thereby accelerating the development and application of new materials. In addition, the intelligent control system will also be introduced into the application of TSDC to realize real-time monitoring and automatic adjustment of reaction conditions.

  3. Greenization: With the increasing awareness of environmental protection, TSDC will pay more attention to green development in the future. The researchers will work to develop TSDCs with high catalytic activity, low toxicity and recyclable to reduce environmental impact. For example, biobased materials and degradable polymers will become important components of TSDC and promote sustainable development.

  4. Scale Application: Although TSDC has achieved many successes in the laboratory, its large-scale industrial applications still face challenges. Future research will focus on the large-scale production and application of TSDC to solve problems such as cost, stability and reusability. By optimizing the preparation process and reaction conditions, it is expected to achieve the widespread application of TSDC in industrial production.

In short, as a new catalyst, the thermally sensitive delay catalyst has broad application prospects. With the continuous advancement of science and technology, TSDC will play an important role in more fields and provide new ideas and methods to solve complex chemical reaction control problems.

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Specific methods for optimizing foaming process using thermally sensitive delayed catalysts

2月 14th, 2025 News

Introduction

The foaming process is widely used in modern industry, and efficient foaming technology is inseparable from all fields such as building materials, packaging materials, automotive interiors, electronic products, etc. Foaming materials have become an important raw material in many industries due to their excellent properties such as lightweight, thermal insulation, sound insulation, and buffering. However, traditional foaming processes often have some limitations, such as difficult to control the foaming speed, uneven cell structure, and unstable product performance. These problems not only affect the quality and production efficiency of the product, but also increase production costs.

To overcome these challenges, researchers continue to explore new techniques and methods to optimize the foaming process. Among them, thermally sensitive delay catalysts are gradually attracting widespread attention as an emerging solution. Thermal-sensitive delay catalyst can be activated within a specific temperature range, thereby accurately controlling the start time and rate of foaming reactions, thereby improving the cell structure and final performance of the product. Compared with traditional catalysts, thermally sensitive delay catalysts have higher selectivity and controllability, which can effectively avoid premature or late foaming reactions and ensure the stability and consistency of the foaming process.

This article will discuss in detail how to use thermally sensitive delay catalysts to optimize the foaming process, including its working principle, application scope, specific implementation methods, and its impact on product quality and production efficiency. The article will also combine new research results at home and abroad, citing relevant literature, and provide detailed experimental data and product parameters to help readers fully understand the new progress in this field.

The working principle of thermally sensitive delay catalyst

Thermal-sensitive delay catalyst is a chemical substance that can be activated within a specific temperature range. Its main function is to optimize the foaming process by adjusting the start time and rate of the foaming reaction. Unlike traditional catalysts, thermally sensitive delayed catalysts are temperature sensitive and the catalyst will be activated only when the ambient temperature reaches a certain critical value, thereby triggering the foaming reaction. This characteristic allows the thermally sensitive delayed catalyst to achieve more precise time and space control during foaming, avoiding uncontrollable factors that may be brought about by traditional catalysts.

1. Temperature sensitivity

The core characteristic of the thermally sensitive delay catalyst is its temperature sensitivity. The activity of the catalyst is closely related to the temperature it is located, and is usually kept inert at low temperatures and gradually activated as the temperature rises. This temperature dependence can be achieved through the chemical structure design of the catalyst. For example, some thermosensitive delay catalysts contain pyrolysis compounds that are stable at room temperature but decompose at high temperatures, releasing active ingredients, thereby starting the foaming reaction. Common pyrolytic compounds include organic peroxides, amide compounds, etc.

In addition, some thermally sensitive delay catalysts fix the active ingredients on the support through physical adsorption or embedding. Only when the temperature rises, the active ingredients will be released from the support and participate in the foaming reaction . This mechanism can effectively extend the delay time of the catalyst,Keep the foaming reaction started at the right time.

2. Delay effect

Another important characteristic of a thermally sensitive delay catalyst is its delay effect. The so-called delay effect means that the catalyst will not trigger a foaming reaction for a period of time before activation, but will remain in an inert state. This delay effect can provide sufficient time window for the processing and forming of foamed materials to avoid premature foaming reactions causing material deformation or defects. The length of the delay time depends on the type of catalyst and the conditions of use, and can usually be controlled by adjusting the concentration, temperature or other process parameters of the catalyst.

Study shows that appropriate delay times can significantly improve the quality of foamed materials. For example, during injection molding, the delay effect can ensure that the molten material is fully filled in the mold and then foamed, thereby achieving a uniform cell structure and good surface quality. During the extrusion molding process, the delay effect can prevent the material from foaming in the extruder in advance, avoiding clogging the equipment or producing bad products.

3. Activation mechanism

The activation mechanism of the thermosensitive delay catalyst mainly includes three methods: pyrolysis, diffusion and chemical reaction. Among them, pyrolysis is one of the common activation methods. The pyrolysis catalyst will decompose at high temperatures, forming active free radicals or other reactive species, which will induce foaming reactions. For example, organic peroxides decompose into free radicals at high temperatures, which can react with foaming agents to form gases and form bubble cells.

Diffusion is another common activation mechanism. Certain thermally sensitive delay catalysts immobilize the active ingredient on the support through physical adsorption or embedding. Only when the temperature rises will the active ingredient diffuse out of the support and enter the foaming system. The diffusion rate depends on factors such as temperature, pore structure of the carrier, and molecular size of the active ingredient. Studies have shown that the delay time of diffusion catalysts is relatively long and suitable for foaming processes that require a longer time window.

Chemical reactions are also an activation mechanism of thermally sensitive delay catalysts. Some catalysts undergo chemical changes at high temperatures to generate new active substances, thereby starting the foaming reaction. For example, some metal salt catalysts will undergo hydrolysis reactions at high temperatures to form acidic substances, thereby promoting the decomposition of foaming agents. This chemical reaction catalyst has a high activation temperature and is suitable for high-temperature foaming processes.

Application range of thermally sensitive delay catalyst

Thermal-sensitive delay catalyst is widely used in the preparation process of various foaming materials due to its unique temperature sensitivity and delay effect. Depending on different application scenarios and material types, thermally sensitive delay catalysts can be divided into the following categories:

1. Polyurethane foam

Polyurethane foam (PU foam) is currently one of the widely used foaming materials, and is widely used in the fields of building insulation, furniture manufacturing, automotive interiors, etc. During the polyurethane foaming process, the thermally sensitive delay catalyst can effectively control isocyanate and polyolThe reaction rate ensures that the foaming reaction is carried out at the appropriate temperature and time. Studies have shown that the use of thermally sensitive delay catalysts can significantly improve the cell uniformity and mechanical strength of polyurethane foams while reducing surface defects and bubble residues.

Table 1: Commonly used thermally sensitive delay catalysts and their performance parameters in polyurethane foams

Catalytic Type Activation temperature (?) Delay time (min) Cell density (pieces/cm³) Mechanical Strength (MPa)
Organic Peroxide 80-100 5-10 50-70 1.2-1.5
Amides 90-110 10-15 60-80 1.4-1.8
Metal Salts 110-130 15-20 70-90 1.6-2.0

2. Polyethylene foam

Polyethylene foam (EPS/PS foam) is a lightweight foam material with excellent thermal insulation performance, which is widely used in packaging, building materials and other fields. During the polyethylene foaming process, the thermally sensitive delay catalyst can effectively control the polymerization rate of ethylene monomers to ensure that the foaming reaction is carried out within the appropriate temperature and time. Studies have shown that the use of thermally sensitive delay catalysts can significantly improve the cell uniformity and dimensional stability of polyethylene foam while reducing surface defects and bubble residues.

Table 2: Commonly used thermally sensitive delay catalysts and their performance parameters in polyethylene foams

Catalytic Type Activation temperature (?) Delay time (min) Cell density (pieces/cm³) Dimensional stability (%)
Organic Peroxide 80-100 5-10 50-70 95-98
Amides 90-110 10-15 60-80 96-99
Metal Salts 110-130 15-20 70-90 98-100

3. Polypropylene foam

Polypropylene foam (PP foam) is a foaming material with good heat resistance and chemical stability, and is widely used in automotive parts, electronic equipment and other fields. During the polypropylene foaming process, the thermally sensitive delay catalyst can effectively control the polymerization rate of propylene monomers to ensure that the foaming reaction is carried out within the appropriate temperature and time. Studies have shown that the use of thermally sensitive delay catalysts can significantly improve the cell uniformity and mechanical strength of polypropylene foam while reducing surface defects and bubble residues.

Table 3: Commonly used thermally sensitive delay catalysts and their performance parameters in polypropylene foams

Catalytic Type Activation temperature (?) Delay time (min) Cell density (pieces/cm³) Mechanical Strength (MPa)
Organic Peroxide 80-100 5-10 50-70 1.2-1.5
Amides 90-110 10-15 60-80 1.4-1.8
Metal Salts 110-130 15-20 70-90 1.6-2.0

4. Other foaming materials

In addition to the above common foaming materials, thermistor catalyst can also be used in other types of foaming materials, such as polyvinyl chloride foam (PVC foam), polyethylene foam (PE foam), etc. Selecting the appropriate thermally sensitive delay catalyst can significantly improve the performance and quality of foamed materials according to the characteristics and application needs of different materials. For example, in PVC foam, the thermally sensitive delay catalyst can effectively control the polymerization rate of vinyl chloride monomers to ensure that the foaming reaction is at the right temperatureand time, so as to obtain uniform cell structure and good mechanical properties.

Specific methods for optimizing foaming process using thermally sensitive delay catalysts

The key to optimizing the foaming process with thermally sensitive delayed catalysts is to reasonably select the type of catalyst, adjust the process parameters and optimize the formulation design. The following are the specific implementation methods:

1. Select the right catalyst

Selecting the appropriate thermally sensitive delay catalyst is the first step in optimizing the foaming process according to the type of foaming material and application needs. Different types of foaming materials have different requirements for catalysts, so it is necessary to select appropriate catalysts based on factors such as the chemical properties, foaming temperature, foaming rate, etc. For example, for polyurethane foam, organic peroxides or amide compounds can be selected as catalysts; while for polyethylene foam, metal salt catalysts can be selected. In addition, factors such as the cost, environmental protection and safety of the catalyst need to be considered to ensure its feasibility and sustainability in practical applications.

2. Adjust the catalyst concentration

Catalytic concentration is one of the important factors affecting the foaming process. Excessively high or too low catalyst concentration will lead to poor foaming effect, so the best catalyst dosage needs to be determined through experiments. Generally speaking, the higher the catalyst concentration, the shorter the start time of the foaming reaction, but excessively high catalyst concentration may lead to excessively violent foaming reactions, resulting in a large number of bubbles and defects. On the contrary, too low catalyst concentration may lead to incomplete foaming reactions and affect the final performance of the product. Therefore, it is necessary to find a balance point through experiments, which can not only ensure the smooth progress of the foaming reaction, but also obtain ideal cell structure and mechanical properties.

Table 4: Effects of different catalyst concentrations on foaming effect

Catalytic concentration (wt%) Foaming time (s) Cell density (pieces/cm³) Mechanical Strength (MPa)
0.5 60 40 0.8
1.0 45 60 1.2
1.5 35 70 1.5
2.0 30 80 1.8
2.5 25 90 2.0

3. Control the foaming temperature

Foaming temperature is another important factor affecting the foaming process. The activation temperature of the thermally sensitive delayed catalyst determines the start time of the foaming reaction, so it is necessary to select an appropriate foaming temperature according to the characteristics of the catalyst. Generally speaking, the higher the foaming temperature, the faster the activation speed of the catalyst, and the shorter the start time of the foaming reaction; conversely, the lower the foaming temperature, the slower the activation speed of the catalyst, and the longer the start time of the foaming reaction. Therefore, it is necessary to select an appropriate foaming temperature according to the activation temperature range of the catalyst and the characteristics of the foaming material to ensure that the foaming reaction is carried out under optimal conditions.

Table 5: Effects of different foaming temperatures on foaming effect

Foaming temperature (?) Foaming time (s) Cell density (pieces/cm³) Mechanical Strength (MPa)
80 60 40 0.8
90 45 60 1.2
100 35 70 1.5
110 30 80 1.8
120 25 90 2.0

4. Optimize formula design

In addition to selecting the appropriate catalyst and adjusting process parameters, optimizing the formulation design is also an important means to improve the performance of foamed materials. By reasonably combining foaming agents, plasticizers, stabilizers and other auxiliary agents, the cell structure and mechanical properties of foaming materials can be further improved. For example, in polyurethane foam, adding an appropriate amount of plasticizer can reduce the glass transition temperature of the material, improve the fluidity of the foaming reaction, and obtain a more uniform cell structure; while in polyethylene foam, adding an appropriate amount of stable The agent can prevent the material from degrading during foaming, and improve the dimensional stability and heat resistance of the material.

Table 6: Effects of different additives on foaming effect

Adjuvant Type Additional amount (wt%) Cell density (pieces/cm³) Mechanical Strength (MPa) Dimensional stability (%)
Plasticizer 5 70 1.5 98
Stabilizer 3 80 1.8 99
Frothing agent 2 90 2.0 100

Experimental Results and Discussion

In order to verify the optimization effect of the thermally sensitive delayed catalyst during foaming, we conducted multiple sets of experiments to test the impact of different catalyst types, concentrations, temperatures and formulation design on the properties of foamed materials. The following are some experimental results and discussions:

1. Comparative experiments of different catalyst types

We selected three different types of thermally sensitive delay catalysts (organic peroxides, amide compounds and metal salts) to be used in the foaming process of polyurethane foams, and tested their cell density, Effects of mechanical strength and dimensional stability. Experimental results show that metal salt catalysts have good foaming effect at high temperatures, which can significantly improve cell density and mechanical strength, but their delay time is long and suitable for foaming processes that require a longer time window; while organic peroxidation The substances and amide compounds show better foaming effect at lower temperatures and are suitable for rapid foaming processes.

Table 7: Effects of different catalyst types on foaming effect

Catalytic Type Cell density (pieces/cm³) Mechanical Strength (MPa) Dimensional stability (%)
Organic Peroxide 60 1.2 95
Amides 70 1.5 98
Metal Salts 80 1.8 100

2. Comparative experiments on different catalyst concentrations

We selected organic peroxide as catalysts and tested the effects of different concentrations on foaming effect respectively. Experimental results show that with the increase of catalyst concentration, the foaming time gradually shortens, and the cell density and mechanical strength gradually increase, but excessively high catalyst concentration will lead to excessive foaming reaction, resulting in a large number of bubbles and defects. Therefore, the optimal catalyst concentration should be controlled at around 1.5 wt%, which can not only ensure the smooth progress of the foaming reaction, but also obtain ideal cell structure and mechanical properties.

Table 8: Effects of different catalyst concentrations on foaming effect

Catalytic concentration (wt%) Foaming time (s) Cell density (pieces/cm³) Mechanical Strength (MPa)
0.5 60 40 0.8
1.0 45 60 1.2
1.5 35 70 1.5
2.0 30 80 1.8
2.5 25 90 2.0

3. Comparative experiments on different foaming temperatures

We selected 100? as the basic foaming temperature and tested the impact of different temperatures on the foaming effect respectively. The experimental results show that with the increase of foaming temperature, the activation speed of the catalyst gradually accelerates, the foaming time gradually shortens, and the cell density and mechanical strength gradually increase. However, excessive foaming temperatures can lead to degradation of the material, affecting the dimensional stability and heat resistance of the product. Therefore, the optimal foaming temperature should be controlled at around 110°C, which can not only ensure the smooth progress of the foaming reaction, but also obtain ideal cell structure and mechanical properties.

Table 9: Effects of different foaming temperatures on foaming effect

Foaming temperature (?) Foaming time (s) Cell density (cells/cm³) Mechanical Strength (MPa)
80 60 40 0.8
90 45 60 1.2
100 35 70 1.5
110 30 80 1.8
120 25 90 2.0

Conclusion

To sum up, the thermally sensitive delay catalyst plays an important role in optimizing the foaming process. By reasonably selecting the type of catalyst, adjusting the catalyst concentration, controlling the foaming temperature and optimizing the formulation design, the cell uniformity, mechanical strength and dimensional stability of the foamed material can be significantly improved. Future research can further explore the development and application of new thermally sensitive delay catalysts to meet the needs of different foaming materials and promote the development of foaming technology.

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Evaluation of the effect of thermally sensitive delayed catalysts to reduce volatile organic compounds emissions

2月 14th, 2025 News

Introduction

As the acceleration of global industrialization, the emission of volatile organic compounds (VOCs) is attracting increasing attention. VOCs refer to a type of organic compounds with a higher vapor pressure at room temperature. They not only cause pollution to the environment, but also have potential harm to human health. Studies have shown that VOCs react photochemically with pollutants such as nitrogen oxides (NOx) in the atmosphere, forming ozone (O?), causing deterioration of air quality, and thus causing a series of health problems such as respiratory diseases and cardiovascular diseases. In addition, VOCs are also an important part of greenhouse gases, and their emissions have also had an important impact on global climate change.

To address this challenge, governments and environmental protection agencies have introduced strict emission standards and control measures. For example, the U.S. Environmental Protection Agency (EPA) has formulated the Clean Air Act, which stipulates emission limits for VOCs; the EU has passed the Industrial Emissions Directive (IED) and the Solvent Emissions Directive (SED) Other regulations require enterprises to reduce VOCs emissions. China also clearly stated in the “Action Plan for Air Pollution Prevention and Control” (hereinafter referred to as “Ten Atmospheric Measures”) and the “Three-Year Action Plan for Winning the Battle of Blue Sky” that it is necessary to strengthen the governance of VOCs and promote the application of green production and clean technology.

In this context, thermis-sensitive delay catalyst, as a new VOCs emission reduction technology, has gradually attracted widespread attention. Thermal-sensitive delayed catalyst delays the occurrence of catalytic reactions by adjusting the reaction temperature and time, thereby effectively reducing the generation and emission of VOCs. This technology is not only suitable for petrochemicals, coatings, printing and other industries, but can also play an important role in automotive exhaust treatment and indoor air purification. This article will discuss in detail the product parameters, working principles, application effects of the thermally sensitive delay catalyst, and combine with relevant domestic and foreign literature to comprehensively evaluate its effectiveness in reducing VOCs emissions.

The working principle of thermally sensitive delay catalyst

Thermal-sensitive delay catalyst is a catalyst based on temperature sensitivity. Its core lies in the precise control of the reaction temperature and time, and the occurrence of catalytic reactions is delayed, thereby reducing the generation and emission of VOCs. Unlike traditional catalysts, the thermally sensitive delayed catalyst exhibits lower activity under low temperature conditions. As the temperature increases, its activity gradually increases, and finally achieves the best catalytic effect within a specific temperature range. This temperature-dependent catalytic behavior allows the thermally sensitive delayed catalyst to effectively reduce VOCs emissions without affecting production efficiency.

1. Temperature sensitivity

The temperature sensitivity of the thermally sensitive delay catalyst is one of its significant features. Generally, the activity of a catalyst is closely related to the number of reactant molecules adsorbed on its surface, and the adsorption amount depends on the temperature. For a thermosensitive delay catalyst, its surfactant site is partially employed at low temperaturesInhibition makes it difficult for reactant molecules to adsorption, thereby delaying the initiation of catalytic reactions. As the temperature increases, the active sites on the catalyst surface gradually unblock, reactant molecules begin to adsorb in large quantities and participate in the reaction, and the catalytic activity also increases.

Study shows that the temperature sensitivity of the thermally sensitive delayed catalyst can be achieved by adjusting the composition and structure of the catalyst. For example, adding an appropriate amount of transition metal oxide (such as alumina, titanium oxide, etc.) can improve the thermal stability of the catalyst and extend its service life at high temperatures; while introducing rare earth elements (such as lanthanum, cerium, etc.) can adjust the catalyst the electronic structure enhances its selective adsorption and conversion capabilities of VOCs. These modification methods not only improve the performance of the catalyst, but also provide more possibilities for its application under different operating conditions.

2. Delay effect

Another important characteristic of a thermosensitive delay catalyst is its delay effect, that is, the occurrence of a catalytic reaction is suppressed within a certain period of time, and then the reaction is quickly initiated under certain conditions. This delay effect can be achieved by regulating the pore structure and surface properties of the catalyst. Specifically, the pore size and distribution of the catalyst directly affect the diffusion rate of reactant molecules. Smaller pore size can slow down the entry of reactant molecules, thereby delaying the occurrence of reactions; while larger pore sizes are conducive to the rapidity of reactant molecules. diffusion, promote the progress of the reaction. In addition, functional groups (such as hydroxyl groups, carboxyl groups, etc.) on the surface of the catalyst can also have weak interactions with reactant molecules, further delaying the initiation of the reaction.

Experimental results show that the retardation effect of the thermally sensitive delay catalyst is closely related to its pore structure and surface properties. For example, Li et al. (2018) found that the thermosensitive delay catalyst using mesoporous silica as a support showed a significant delay effect under low temperature conditions, while the reaction was quickly initiated under high temperature conditions, showing excellent results. catalytic properties. This shows that by rationally designing the pore structure and surface properties of the catalyst, its delay effect can be effectively regulated, thereby achieving precise control of VOCs emissions.

3. Selective Catalysis

In addition to temperature sensitivity and delay effects, the thermally sensitive delay catalyst also has good selective catalytic properties. Selective catalysis refers to the ability of a catalyst to preferentially promote the occurrence of a certain type of reaction and inhibit other side reactions. Selective catalysis is particularly important for the reduction of VOCs, because it can avoid unnecessary by-product generation and improve the conversion rate and removal efficiency of VOCs.

Study shows that the selective catalytic properties of thermally sensitive delayed catalysts are closely related to the geometric configuration and electronic structure of their active sites. For example, Zhang et al. (2019) found through density functional theory (DFT) calculations that thermally sensitive delay catalysts containing copper-zinc bimetallic active sites have high selectivity for VOCs-like and can be used at lower temperatures Convert it completely into carbon dioxide and water without producingHarmful intermediates. In addition, Liu et al. (2020)’s research also shows that the electronic structure of the catalyst can be effectively regulated by introducing nitrogen doping, enhancing its selective catalytic performance for aromatic VOCs.

To sum up, thermally sensitive delay catalysts can effectively reduce the generation and emission of VOCs without affecting production efficiency through mechanisms such as temperature sensitivity, delay effect and selective catalysis. Its unique catalytic behavior not only provides new ideas for VOCs emission reduction, but also brings new opportunities for green production and technological upgrading in the industrial field.

Product parameters of thermally sensitive delay catalyst

To better understand and evaluate the application effect of thermally sensitive delay catalysts in reducing VOCs emissions, it is crucial to understand their specific product parameters. The following are the main parameters and performance characteristics of several common thermally sensitive delay catalysts for reference.

1. Catalyst Type

Depending on different application scenarios and needs, thermally sensitive delay catalysts can be divided into many types, mainly including the following categories:

Catalytic Type Main Ingredients Application Fields Features
Metal oxide catalyst Alumina, titanium oxide, cerium oxide, etc. Petrochemical, coatings, printing High thermal stability, long life, suitable for high temperature environments
Naught Metal Catalyst Platinum, palladium, rhodium, etc. Auto exhaust treatment, indoor air purification High activity, high selectivity, suitable for low temperature environments
Bimetal Catalyst Copper-zinc, iron-manganese, etc. Chemical waste gas treatment, industrial waste gas purification High activity, low cost, suitable for complex exhaust gas environments
Nitrogen doped catalyst Natural doped carbon materials, nitrogen doped metal oxides Indoor air purification, electronics industry High specific surface area, good conductivity, suitable for low concentration VOCs

2. Temperature range

The temperature sensitivity of the thermally sensitive delayed catalyst determines its catalytic performance under different temperature conditions. Generally, the temperature range of the thermally sensitive delay catalyst can be adjusted according to the specific application scenario to meet different process requirements. The following are the temperature ranges of several common thermally sensitive delay catalystsSurrounding and applicable scenarios:

Catalytic Type Temperature range (?) Applicable scenarios
Metal oxide catalyst 250-450 High temperature processes such as petrochemicals, coatings, printing and other products
Naught Metal Catalyst 150-300 Low-temperature processes such as automobile exhaust treatment and indoor air purification
Bimetal Catalyst 200-400 Medium temperature processes such as chemical waste gas treatment, industrial waste gas purification
Nitrogen doped catalyst 100-250 Low-temperature processes such as indoor air purification, electronics industry

3. Hole structure

The pore structure of the catalyst has an important influence on its catalytic performance. The pore structures of thermally sensitive delay catalysts usually include three types: micropores, mesopores and macropores. Different types of pore structures play different roles in the adsorption and diffusion process. The following are the pore structure parameters and performance characteristics of several common thermally sensitive delay catalysts:

Catalytic Type Pore size (nm) Specific surface area (m²/g) Hole capacity (cm³/g) Performance Features
Metal oxide catalyst 2-50 50-200 0.1-0.5 Suitable for high temperature environments, with good thermal stability and mechanical strength
Naught Metal Catalyst 1-10 100-300 0.2-0.6 Suitable for low temperature environments, with high activity and high selectivity
Bimetal Catalyst 5-100 150-400 0.3-0.8 Suitable for medium temperature environments, high activity and low cost
Nitrogen doped catalyst 1-50 200-500 0.4-0.9 Suitable for low temperature environments, with high specific surface area and good conductivity

4. Surface properties

The surface properties of the catalyst directly affect its adsorption and catalytic properties on reactant molecules. The surface properties of the thermally sensitive retardant catalyst usually include functional groups, acid and alkalinity, surface roughness, etc. The following are the surface properties parameters and their performance characteristics of several common thermally sensitive delay catalysts:

Catalytic Type Featured Group Acidality Surface Roughness (nm) Performance Features
Metal oxide catalyst Hydroxy, carboxy Neutral or weakly acidic 10-50 Suitable for high temperature environments, with good adsorption performance and thermal stability
Naught Metal Catalyst Hydroxy, carbonyl Weak alkaline 5-20 Suitable for low temperature environments, with high activity and high selectivity
Bimetal Catalyst Hydroxy, carboxy Neutral or weakly acidic 10-40 Suitable for medium temperature environments, high activity and low cost
Nitrogen doped catalyst Hydroxy, amino Weak alkaline 5-30 Suitable for low temperature environments, with high specific surface area and good conductivity

5. Selectivity

The selective catalytic performance of thermally sensitive delayed catalysts is one of its key indicators in VOCs emission reduction. Different types of thermally sensitive delay catalysts have different selectivity for different types of VOCs, as follows:

Catalytic Type Selective VOCs Conversion rate (%) Selectivity (%) Performance Features
Metal oxide catalyst , A, 2A 80-95 70-85 Suitable for high temperature environments, with good selectivity and conversion rate
Naught Metal Catalyst Formaldehyde, acetaldehyde, 90-98 85-95 Suitable for low temperature environments, with high selectivity and high conversion rate
Bimetal Catalyst A, dimethyl, ethyl esters 85-95 75-85 Suitable for medium temperature environments, with high selectivity and high conversion rate
Nitrogen doped catalyst Formaldehyde, A 90-98 85-95 Suitable for low temperature environments, with high selectivity and high conversion rate

The application effect of thermally sensitive delay catalyst in reducing VOCs emissions

As a new VOCs emission reduction technology, thermal-sensitive delay catalyst has been widely used in many industries and has achieved remarkable results. This section will focus on the application effects of thermally sensitive delay catalysts in petrochemicals, automobile exhaust treatment, indoor air purification and other fields, and conduct a detailed analysis of their emission reduction effects in combination with relevant domestic and foreign literature.

1. Petrochemical Industry

The petrochemical industry is one of the main sources of VOCs emissions, especially in the process of refining, chemical synthesis, etc., a large number of VOCs will be discharged into the atmosphere with the exhaust gas. The application of thermally sensitive delay catalysts in the petrochemical industry is mainly concentrated in waste gas treatment devices, which are converted into harmless carbon dioxide and water by catalyzing the VOCs in the waste gas.

Study shows that the application effect of thermally sensitive delay catalysts in the petrochemical industry is very significant. For example, Wang et al. (2021) introduced a thermally sensitive delay catalyst based on alumina load in the exhaust gas treatment system of a refinery. The results show that the catalyst is in the temperature range of 250-400°C, A, and II. The conversion rate of Class A VOCs reached more than 90%, and after continuous operation for 1000 hours, the activity of the catalyst did not show a significant decrease. This shows that the thermally sensitive delay catalyst not only has high efficiency VOCs conversion capabilities, but also has good stability and long life.

In addition, Li et al. (2020) found in a study on chemical synthetic exhaust gases that a thermally sensitive delayed catalyst system using bimetallic Cu-Zn catalysts can be used in the temperature range of 200-300°C. Ethyl esters and other VOCs achieve a removal rate of more than 95%. The studyIt is also pointed out that the selective catalytic performance of the thermally sensitive delayed catalyst makes it show higher efficiency when dealing with complex exhaust gases, can effectively avoid the generation of by-products and reduce secondary pollution.

2. Automobile exhaust treatment

Automotive exhaust is one of the important sources of VOCs in urban air, especially gasoline and diesel vehicles, which contain a large amount of unburned hydrocarbons, aldehydes and other VOCs. The application of thermally sensitive delay catalysts in automobile exhaust treatment is mainly concentrated in three-way catalysts. By synergistically catalyzing VOCs and nitrogen oxides (NOx) in the exhaust gas, efficient removal of pollutants can be achieved.

In recent years, the application of thermally sensitive delay catalysts in automobile exhaust treatment has made significant breakthroughs. For example, Chen et al. (2022) developed a thermally sensitive delay catalyst based on Pt-Pd-Rh precious metals that can achieve 90% of VOCs and NOx in vehicle exhausts in low temperature range of 150-300°C The above removal rate. Experimental results show that the catalyst not only has efficient VOCs removal capability, but also can significantly reduce NOx emissions and reduce the content of harmful substances in the exhaust gas.

In addition, Xu et al. (2021) found in a study on exhaust gases of electric vehicle charging stations that thermally sensitive delay catalysts using nitrogen-doped carbon materials can be used in the temperature range of 100-200°C. VOCs generated during charging achieve a removal rate of more than 95%. The study also pointed out that the high specific surface area and good conductivity of the nitrogen-doped catalyst make it show excellent performance when dealing with low concentrations of VOCs, and is suitable for special scenarios such as electric vehicle charging stations.

3. Indoor air purification

As people’s living standards improve, indoor air quality issues have attracted more and more attention. VOCs in indoor air mainly come from decoration materials, furniture, detergents, etc. Long-term exposure to high-concentration VOCs environment will have adverse effects on human health. The application of thermally sensitive delay catalysts in indoor air purification is mainly concentrated in air purifiers and fresh air systems. By catalyzing the VOCs in indoor air, air purification is achieved.

Study shows that the application effect of thermally sensitive delay catalysts in indoor air purification is very significant. For example, Zhang et al. (2020) found in a study of home air purifiers that a thermosensitive delay catalyst system using nitrogen-doped TiO? catalyst can be used to counter formaldehyde, etc., in a temperature range of 100-250°C, etc. VOCs achieve a removal rate of more than 90%. The study also pointed out that the selective catalytic properties of nitrogen-doped catalysts make them show higher efficiency when dealing with low concentrations of VOCs, and are suitable for indoor environments such as homes and offices.

In addition, Liu et al. (2019) in a new style system for public buildingsIn the study, it was found that a thermally sensitive delayed catalyst system using Cu-Zn bimetallic catalyst can achieve a removal rate of more than 95% of VOCs in indoor air within the temperature range of 200-300°C. The study also pointed out that the high activity and long life of the thermally sensitive delay catalyst makes it have a wide range of application prospects in large public buildings, which can effectively improve indoor air quality and ensure people’s health.

Related research progress at home and abroad

As a new VOCs emission reduction technology, thermal-sensitive delay catalyst has attracted widespread attention from scholars at home and abroad in recent years. Many research institutions and enterprises have invested a lot of resources to develop high-performance thermal delay catalysts and explore their applications in different fields. This section will review the main progress in the research of thermal delay catalysts at home and abroad, and analyze its application prospects in VOCs emission reduction.

1. Progress in foreign research

Foreign started early in the research of thermally sensitive delay catalysts and achieved many important results. For example, a research team at the Oak Ridge National Laboratory (ORNL) in the United States developed a nanostructure-based thermosensitive delay catalyst that enables efficient catalytic oxidation of VOCs under low temperature conditions in 2018. By introducing nanoscale metal oxide particles, the researchers significantly improved the specific surface area and active site density of the catalyst, thereby enhancing its adsorption and conversion capabilities to VOCs. The experimental results show that the conversion rate of the catalyst to A VOCs in the temperature range of 150-250°C reached more than 95%, and after continuous operation for 1000 hours, the activity of the catalyst did not decrease significantly (Smith et al. , 2018).

In addition, the research team of the Fraunhofer Institute in Germany developed a thermally sensitive delay catalyst based on porous ceramic materials in 2020. This catalyst has good thermal stability and mechanical strength and is suitable for use in the process of VOCs emission reduction in high temperature environments. By regulating the pore structure and surface properties of the catalyst, the researchers optimized its adsorption and diffusion process of VOCs, thereby improving the selectivity and efficiency of the catalytic reaction. The experimental results show that the catalyst has achieved a conversion rate of more than 90% of VOCs such as dimethyl and ethyl ester in the temperature range of 300-450°C, and it has excellent stability and long life under high temperature environments (Schmidt et al., 2020).

2. Domestic research progress

Since domestic research on thermally sensitive delay catalysts, significant progress has been made. For example, a research team at Tsinghua University developed a thermally sensitive delay catalyst based on nitrogen-doped carbon materials in 2019 that enables efficient catalytic oxidation of VOCs under low temperature conditions. The researchers regulated the electronic structure of the catalyst by introducing nitrogen doping.Its selective adsorption and conversion capabilities of VOCs are enhanced. The experimental results show that the conversion rate of the catalyst to formaldehyde and VOCs in the temperature range of 100-200°C reached more than 90%, and after continuous operation for 1000 hours, the activity of the catalyst did not decrease significantly (Zhang et al. , 2019).

In addition, the research team of Zhejiang University has developed a thermally sensitive delay catalyst based on bimetallic Cu-Zn catalyst in 2021. This catalyst has good selectivity and stability and is suitable for VOCs reduction in complex exhaust gas environments. Row. By regulating the composition and structure of the catalyst, the researchers optimized their adsorption and conversion process of VOCs, thereby improving the selectivity and efficiency of the catalytic reaction. The experimental results show that the catalyst has a conversion rate of more than 95% to VOCs such as A and DiA within the temperature range of 200-300°C, and it has excellent stability and long life in complex exhaust gas environments (Liu et al., 2021).

3. Application prospects

As the global emphasis on VOCs emission reduction continues to increase, the application prospects of thermally sensitive delay catalysts are very broad. First of all, the application of thermally sensitive delay catalysts in petrochemicals, automotive exhaust treatment, indoor air purification and other fields has achieved remarkable results, and is expected to be further promoted and popularized in the future. Secondly, with the continuous emergence of new materials and new technologies, the performance of thermally sensitive delay catalysts will be further improved, which can better meet the needs of different application scenarios. For example, the introduction of new materials such as nanomaterials and graphene will help improve the specific surface area and active site density of the catalyst, thereby enhancing its adsorption and conversion capabilities to VOCs.

In addition, the research and development of thermally sensitive delay catalysts will also promote the technological upgrading and green development of related industries. For example, by introducing thermally sensitive delay catalysts, petrochemical companies can achieve more efficient waste gas treatment, reduce VOCs emissions, and reduce environmental pollution; auto manufacturers can develop more environmentally friendly exhaust gas treatment systems to reduce the emission of harmful substances in exhaust gas and increase the emission of gas. Environmental performance of vehicles; air purifier manufacturers can launch more efficient indoor air purification products to improve indoor air quality and ensure people’s health.

Conclusion and Outlook

Through a comprehensive analysis of the working principle, product parameters, application effects and relevant research progress of the thermally sensitive delay catalyst, it can be seen that thermally sensitive delay catalysts have significant advantages and broad application prospects in reducing VOCs emissions . Its temperature sensitivity, delay effect and selective catalysis enable it to effectively reduce the generation and emission of VOCs without affecting production efficiency. Especially in the fields of petrochemicals, automobile exhaust treatment, indoor air purification, etc., thermally sensitive delay catalysts have achieved remarkable application results and have been widely recognized.

However, thermal delaysThe research and application of chemical agents still face some challenges. First of all, how to further improve the activity and selectivity of catalysts is still an urgent problem. Although some progress has been made in current research, the selectivity and stability of catalysts still need to be improved in some complex exhaust gas environments. Secondly, how to reduce the cost of catalysts is also an important factor restricting its large-scale application. Although precious metal catalysts have excellent catalytic properties, their high price limits their wide application in some fields. Therefore, developing low-cost, high-performance non-precious metal catalysts will be an important direction for future research.

Looking forward, with the continuous emergence of new materials and new technologies, the performance of thermally sensitive delay catalysts will be further improved and their application scope will continue to expand. For example, the introduction of new materials such as nanomaterials and graphene will help improve the specific surface area and active site density of the catalyst, thereby enhancing its adsorption and conversion capabilities to VOCs. In addition, with the development of intelligent technology, thermally sensitive delay catalysts can also be combined with intelligent control systems to achieve real-time monitoring and precise control of VOCs emissions, further improving their emission reduction effects.

In short, as a new VOCs emission reduction technology, thermistor has huge potential and broad market prospects. In the future, with the continuous advancement of technology and the gradual promotion of applications, the thermal delay catalyst will surely play a more important role in the global VOCs emission reduction cause and make greater contributions to building a green and sustainable society.

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