How long can this type of catalyst be used in catalytic combustion?

Currently commonly used catalytic combustion devices mainly use precious metal catalysts, which can have a great impact on organic waste gas in a certain period of time. The service life of the catalyst is usually two to four years. So the cost of the catalyst should also be included in the life of the catalytic incinerator.

Combustion Temperature Adjustment: The temperature of the catalytic combustion device is adjustable, by inputting the temperature you wish to change in the PLC system, or changing the output frequency of the frequency converter, to adjust the appropriate air volume.

As the air volume increases, the combustion temperature of the catalytic combustion device will be higher than the set value, and the PLC-controlled frequency converter will reduce the output frequency, decrease the airflow, and stabilize the temperature of the whole device.

If the output frequency of the frequency converter is lower than the set value, but the output capacity is still higher than the set value, the programmable controller starts timing. When the frequency is at a certain set value, the programmable logic controller will give up the timing. Continuous inverter operation.

When the temperature is higher than the set value for a period of time, the programmable logic controller will keep adjusting until the set value is reached. After running PID, the programmable controller controls the inverter frequency output. As the temperature decreases, the frequency will increase, thus retaining a certain time delay.

After burning the catalyst for a period of time, carbon buildup will occur in the catalyst, so how to deal with this situation? Place the catalyst in fresh air, heat it up to 500°C and keep it for 2-4 hours to remove or partially remove the carbon buildup.

What role does the catalyst play in the foamed products of polyurethane foaming machine?

A catalyst is a substance that can change the speed of a chemical reaction without being consumed itself. A good catalyst should have the following characteristics:

1. increase the selectivity of the reaction

2. reduce energy consumption i.e. speed up the reaction;

3. reduce the number of steps and by-products, i.e., the raw material is completely transformed into the target product. In polyurethane foamer chemistry since the discovery of the reaction of diisocyanates with hydroxyl compounds to produce rigid foams, coatings and adhesives, polyurethane foamer products have been used in a variety of applications. A wide range of applications are still being developed.

Foaming Machines

Demand always promotes the development of scientific research. Polyurethane blowing agent rigid foam, for example, in all thermal insulation materials, although polyurethane blowing agent foam in all aspects of the performance is good, and the cost is also high, one of the reasons is the overall density of the foamed products is high; in the production process, although flexible and convenient, but the material in the reaction process of the operation of the process conditions of sensitivity to make the quality of the product fluctuations, the need to adjust the formula often for the products of the production plant to lose, of course, some of the problems to increase the amount of feed is also a solution to the problem, but also to increase the amount of feed is also a solution to the problem. Of course, some of the problems to increase the amount of feed is also a way to solve the problem, the result is to increase the cost of the price;

Foaming machine

The temperature resistance of polyurethane foaming agent can not exceed 120 degrees; in the flame retardant added flame retardant effect flame retardant up to B2. in the application are difficult. It is these weaknesses become a bottleneck in the development of polyurethane foaming foam. To solve this bottleneck problem to first understand the current factors affecting quality fluctuations and high density and other issues. From the molded foam molding characteristics, foaming is the injection operation, the foam has the problem of flow, if the foam flow is not good in the polyurethane foaming machine foaming products in the density of the foam is not consistent, this time to use more material to make the density of the low density can also reach the qualified strength and skin. How to achieve the density of the same, in the process of foaming reaction to control the mobility of the foam is a way, why the environmental process conditions on the quality of the product so much influence.

Foaming machine

Good balance, so that the rate of polymer formation and gas generation is balanced with each other, in the gas reaction at the same time the foam wall has enough strength, the gas is effectively encapsulated in the foam body, foaming is completed after solidification and molding. At present, there are two major types of catalysts: tertiary amine catalysts and organometallic salt catalysts, tertiary amine catalysts are represented by triethylenediamine and NN-dimethylcyclohexylamine, and organometallic metal catalysts are organotin catalysts and carboxylate catalysts. Although there are many catalysts of the above types available, people are repeatedly testing them according to the strength of the catalytic activity. Taking pouring molding as an example, people have to control the foaming and curing time according to the shape and size of the products, and have to repeatedly adjust the two types of catalysts to find out the balance of foaming and gelation so as to increase the mobility of the foams and the molding. However, due to the elasticity and toughness of polyurethane, the foam is elongated in the middle and late stages of foaming.

The understanding of the nature of catalytic action, first of all, is to study the catalyst active center / active phase, that is, to unlock the so-called “black box” secret; study its size, shape, composition, composition of the interactions between the catalytic performance of the correlation between the catalytic performance, in particular, the use of a variety of modern physicochemical means at the atomic and molecular level in real time, real-space access to basic information to be studied. The basic information is studied.

In 1925, H.S. Taylor proposed the concept of active center, which implies that the catalytic “site” is not the entire surface of the catalyst, but some specific “parts” of the catalyst, i.e., the active center/active phase.

Temperature Programmed Desorption (TPD), is a method in which a catalyst with certain gas molecules adsorbed in advance is heated under a programmed heating process, and the molecules adsorbed on the surface of the catalyst are desorbed by means of a stable flow rate of a gas (usually an inert gas, e.g., He) at a certain temperature, and the rate of desorption increases with the increase of the temperature, after a high value. As the temperature increases, the desorption speed increases, and the desorption is completed after a high value. The concentration of the desorbed gas can be detected with a thermal conductivity detector to determine the temperature dependence of the gas and obtain a TPD curve. The alkaline gas desorbed is absorbed by acid, and the amount of acid consumed can be determined by titration to obtain the total amount of acid in the catalyst. The titration step can also be completed automatically by the chemisorption instrument to obtain the accurate desorption amount directly.

TPR (Temperature-ProgrammedReduction) is developed on the basis of TPD. It can provide information on the interaction of metal oxides with each other or between metal oxides and carriers during the reduction process of loaded metal catalysts. The method and principle are as follows: A pure metal oxide has a specific reduction temperature, which can be used to characterize the properties of the oxide. If another oxide is introduced in the oxide, the two oxides are mixed together. If each oxide keeps its own reduction temperature constant during the TPR process, they do not interact with each other.

Conversely, if the two oxides interact in a solid-phase reaction and the nature of the oxides changes, the original reduction temperature is changed. This change can be recorded using the TPR technique. So TPR is an effective method to study the interaction between metal oxides and metal oxides and between metal oxides and carriers in loaded catalysts.

In hydrocarbon reactions, hydrocarbons are reduced to carbon monomers deposited on the surface of the catalyst, and this deposited carbon monomers are called carbon deposits. Due to the carbon buildup, the catalyst activity decays. Therefore, it is important to study the kinetics and reaction mechanism of carbon accumulation to reduce the occurrence of carbon accumulation and extend the catalyst life. For the study of the carbon accumulation mechanism on single crystal surfaces, relevant models have been proposed. However, for commonly used catalysts, the relationship between metal surface structure and carbon accumulation is more complicated due to the role of carriers.TPO (Temperature Programmed0xidization) is a more sensitive method to study the carbon accumulation of catalysts and correlate it with the reaction performance.

Acidic sites on solid surfaces can generally be regarded as active sites on the surface of oxide catalysts. In many catalytic reactions such as catalytic cracking, isomerization, polymerization, etc. hydrocarbon molecules interact with the surface acidic sites to form n-carbon ions, which are intermediate species of the reaction. The theory of positive carbon ions can successfully explain the reactions of hydrocarbons on acidic surfaces and also provides a strong proof for the existence of acidic sites.

In order to characterize solid acid catalysts, the type (Lewis acid, Bronsted acid), strength and amount of acid on the surface acidic sites need to be determined. There are many methods to determine the surface acidity, such as alkali titration, alkaline gas adsorption, thermal difference method, etc., but none of these methods can distinguish between L and B acid sites.AMI-300IR in situ infrared & programmed elevated temperature chemisorbentiometry was used to study the surface acidity of solid catalysts, which can effectively distinguish between L and B acids.In this method, alkaline adsorbent such as ammonia, pyridine, trimethylamine, and n-butylamine are commonly used to characterize the acidic sites, of which the more widely used are pyridine and ammonia.

Propylene tri- and tetramer is an important chemical raw material. At present, the more mature propylene zwitterionic catalysts mainly include three kinds: solid phosphoric acid catalysts, solid acid catalysts and homogeneous catalysts.

Solid Phosphoric Acid Catalysts: Low Zwitterion Selectivity

Solid phosphate catalysts are generally made of diatomaceous earth, aluminum silicate or silica sol as the carrier, and loaded with a certain amount of phosphoric acid through blending or impregnation method, and then calcined at high temperature to obtain solid phosphate catalysts with a certain amount of acid. The reaction mechanism of these catalysts is that the propylene feedstock is firstly cracked under the action of acid to generate positive carbon ions, and then the monomolecule combines with the positive carbon ions to realize the chain growth, and then the chain termination is completed by proton transfer.

Solid phosphoric acid catalyst (SPAC) plays a dominant role in the polymerization of propylene, and the commonly used phosphates are Cu, Ni, Ca and ammonium salts. The activity of SPAC comes from the free phosphoric acid released by the slow hydrolysis of the catalyst during operation, and the size of the P2O5/H2O ratio (PWR) on the surface of the catalyst affects the rate of hydrolysis of the catalyst and the concentration of the free phosphoric acid produced by the hydrolysis, FPA. FPA is the key factor affecting the activity and lifetime of solid phosphoric acid catalysts. With small PWR, the hydrolysis rate is fast and the equilibrium FPA concentration is large, which results in a high activity but a rapid increase in the pressure drop in the reactor bed and a rapid sludging failure of the catalyst. On the other hand, if the FPA concentration is small, although it can reduce the hydrolysis rate and ease the pressure drop and sludging tendency, but the activity is low, and may even be inactivated due to the loss of surface of the catalyst, so the water content of the reactor feed must be adjusted according to the change of reaction conditions.

Solid phosphate catalytic process using phosphoric acid – diatomaceous earth or phosphoric acid – silica gel as catalyst, despite the high surface activity of the catalyst, the process is reasonable, but the three polymer, tetrapolymer above the selectivity is low, the use of short-life, in the reaction process should be strictly controlled by the amount of water injected into the catalyst, or else the catalyst is prone to sludging, clumping and so on. The solid phosphoric acid/diatomaceous earth catalyst developed by U.S. Universal Oil Products (UOP) in the 30’s has been widely used, but it has the problems of low mechanical strength, easy to sludge and agglomerate, and regeneration difficulties, etc. Phosphate catalysts with activity, selectivity and strength are all high and have a long service life is the direction.

Optimize the process to improve the selectivity

Propylene zwitterionic process of cracking to generate low-carbon olefin re-addition of non-zwitterionic products is a low-value by-products, the main factors affecting the selectivity of non-zwitterionic products is the reaction temperature and contact time, with the rise of reaction temperature and the extension of the contact time, the tendency to increase the zwitterionic cleavage of cracked products re-addition of non-zwitterionic products generated by the cracked products. The selectivity of propylene trimer decreases with the increase of reaction temperature, the selectivity of tetramer increases with the increase of reaction temperature, the selectivity of propylene trimer decreases with the increase of contact time, while the selectivity of tetramer increases with the increase of contact time.

In order to obtain high zwitterionic selectivity, lower reaction temperatures and higher air velocities should be used as much as possible in the propylene zwitterionization process to maintain a moderately low one-way conversion of propylene. Nickel-loaded catalysts, such as NiSO4/γ-A12 O3, were used as catalysts, which showed good low-temperature catalytic activity and stability in the propylene zwitterionization reaction. By changing the process reaction conditions, the low-temperature-high-temperature two-stage reaction method of connecting two fixed-bed reactors in series, one stage of the reaction is to utilize the good low-temperature catalytic activity of NiSO4/γ-A12 O3 catalysts to synthesize propylene dimer with high selectivity, and the second stage of the reaction is to transform propylene dimer into tetramer and hexamer of propylene with high selectivity again at a higher temperature. In this way, the non-selective zwitterionic reaction that usually occurs on solid acid catalysts is transformed into a directional zwitterionic reaction with a certain degree of selectivity, and long-chain olefins such as dodecene and octadecene are synthesized in high yields, and a small amount of nonene is generated at the same time.

Difficulty of solid acid catalyst in selectivity

Solid acid catalysts have better activity in the polymerization of low carbon olefins for the preparation of high value-added high carbon olefin products, among which zeolite molecular sieves have the advantages of environmental friendliness, renewability and adjustability of product composition. The uniqueness of molecular sieve catalysts for catalyzing the propylene zwitterionic reaction lies in their regular pore structure, which has a strong screening ability for olefin molecules. The reaction temperature and pressure of molecular sieve catalysts for catalyzing the propylene zwitterionic reaction are high, and the reaction temperature, reaction pressure, the type of molecular sieve, the silica-aluminum ratio, and the type of the loaded metal cations have an effect on the reaction. By proper control of these factors, different product distributions can be obtained, which is an important means for molecular tailoring of the zwitterion. Due to the strong adsorption property of the molecular sieve and the uniform distribution of the active center, it can induce the propylene molecules adsorbed on the surface of the molecular sieve to react rapidly.

1.1 Raw materials

Neopentyl glycol, industrial grade, Wanhua Chemical Group Co., Ltd; ethylene glycol, industrial grade, Shandong Hengxin Chemical Co., Ltd; diethylene glycol, industrial grade, Guangzhou Canlian Chemical Co., Ltd; terephthalic acid, industrial grade, Jinan Auchen Chemical Co.

PC9800, PC4100 and PC779 are white powder, PC380 and PC918 are slightly yellow oily liquid. pc4100 is monobutyltin oxide, pc9800 and pc918 are chelates of tin, pc779 and pc380 are derivatives of monobutyltin oxide. Since butyltin is not environmentally friendly, PC4100, PC779 and PC380, which contain butyltin components, are subject to foreign export restrictions, while PC9800 and PC918 are new environmentally friendly catalysts as they do not contain harmful components such as butyltin.

1.2 Instrument

ZNHW Intelligent Temperature Control Instrument, Shanghai Purdue Science and Technology Co., Ltd; WAY2S Digital Abbe Refractometer, Shanghai Precision Scientific Instrument Co., Ltd; PLGPC50 Gel Permeation Chromatograph, Beijing Pritik Instrument Co.

1.3 Synthesis of two polyester resins

EG-PTA polyester resin is a polymerization system with ethylene glycol (EG), diethylene glycol (DEG) and terephthalic acid (PTA) as raw materials, and NPG-PTA polyester resin is a polymerization system with neopentyl glycol (NPG) and terephthalic acid (PTA) as raw materials. The synthesis process of EG-PTA polyester resin was as follows: according to the mass fractions of 18.93%, 15.37% and 65.75%, respectively, weighed a total mass of 1.6 kg of ethylene glycol, diethylene glycol and terephthalic acid, and the dosage of five kinds of organotin catalysts was 0.08% of total mass. The weighed ethylene glycol and diethylene glycol were poured into a 2L four-necked flask, heated up to 85 ℃, and the stirring speed was set to 150 r/min. The organotin catalysts and terephthalic acid were added into the flask, and the temperature was heated up to 180 ℃, and the stirring speed was set to 200 r/min. The refluxing was performed for 40 min, and then the temperature was heated to 240 ℃ in stepwise manner by connecting the condensate, and the reaction time, the reaction temperature, the condensate temperature, and the water output were recorded. The reaction time, reaction temperature, condensation temperature and water output were recorded. The condensation temperature decreased to indicate that no water was generated during the reaction, which was regarded as the end point of the reaction, and the refractive index of the esterified water was determined.The synthesis process of NPG-PTA polyester resin was the same as that of EG-PTA polyester resin, in which the reaction was carried out according to the mass fractions of 40% and 40%, respectively.

In view of this, Liangbing Hu’s group reported a high-temperature, fast-pulse-based heat treatment method to achieve efficient regeneration of catalyst-loaded electrodes. In this process, the high temperature ensures that the by-products accumulated on the surface of the electrode can be completely decomposed, while the extremely short heating time allows the original physicochemical properties of the catalyst to be maintained, and thus the catalytic activity similar to that of the virgin electrode is demonstrated in the reuse.

In this paper, the method was applied to the ruthenium-loaded porous carbon electrode for lithium-air batteries as an example, and the service life of the ruthenium-loaded porous carbon electrode was extended by a factor of nearly ten by applying the method for up to ten regeneration cycles. The method can be flexibly applied to other systems, thus greatly extending the lifetime of electrochemical systems deactivated due to by-product accumulation. This research opens a new avenue for sustainable applications of electrochemical energy storage and energy conversion devices.

Background

In recent years, electrochemical energy storage and energy conversion technologies have been rapidly developed, with a variety of new fuel cells, electrolytic cells, energy storage devices and organic electrochemical synthesis technologies. In most of these electrochemical systems, the electrode reactions rely on efficient heterogeneous catalysts to realize the effect of lowering the overpotential and increasing the current density. Most of these catalysts are based on transition metals or even precious metals, which are not only expensive but also potentially harmful to the environment. Especially for waste electronics, improper disposal will not only cause economic loss, but also bring long-term environmental pollution. In the field of academic research, compared with the unremitting pursuit of high catalyst activity, the recycling and regeneration technology of catalysts and their electrode materials have been developed quite slowly.

For the deactivation of catalyst-loaded electrodes in electrochemical systems, most of the causes are due to the deposition of by-products on the surface of electrodes and catalysts from the degradation of reactants, solvents and active substances in carbon electrodes or electrolytes, and the continuous accumulation of such by-products will lead to gradual deactivation of the electrodes and their eventual failure. For the recovery of electrochemical devices, there are currently pyrometallurgical, hydrometallurgical and thermohydrometallurgical extraction methods, followed by leaching, purification, separation, secondary synthesis and other subsequent steps. However, conventional methods often recover only a fraction of the metal material. Although the idea of direct regeneration and reuse of catalyst-loaded electrodes has been proposed, the technology has not been effectively developed, and existing reports are limited to applications such as hydrothermal treatment, calcination, and chemical coating modification in a single system.

To address this issue, this paper reports an efficient electrode material regeneration technique based on high-temperature pulsed heat treatment for the direct reuse of catalyst-loaded electrode materials. This method realizes radiant heating by Joule heating the carbon material, and employs precise control of the current to rapidly elevate the used catalyst-loaded electrodes to high temperatures, e.g., 1700 K, and cool them down within a few tens of milliseconds. Although the process is short-lived, it has the effect of cleaning up by-products and greatly extending the service life of the electrodes. In this process, the high temperature helps to remove by-products through decomposition and evaporation mechanisms, thus restoring the effective surface area of the electrode and the catalyst activity. At the same time, rapid cooling allows the original physicochemical properties of the catalyst to be maintained, so that it will exhibit similar performance when it is reused. The deactivated ruthenium-loaded porous carbon electrode can be regenerated and reused up to 10 times when using lithium-air batteries as an example. The method is very versatile and can be flexibly extended to other substrate materials and catalyst systems.

Analysis of results

In order to realize an efficient and fast regeneration process for catalyst-loaded electrodes, a Joule heating-based regeneration device was first designed and validated in this paper (Fig. 1). After a long period of use, the performance of the electrode material is greatly reduced due to a large number of by-products accumulated on the surface of the electrode and catalyst. In this paper, we firstly designed a sandwich Joule heating method, in which the electrode material to be regenerated is placed in the middle position, and instantaneous current injection is used to bring high temperature and quickly cut off the power supply in order to realize instantaneous heat treatment. Since carbon material has low density and low heat capacity when used as a heating source, it can be rapidly reduced from a high temperature of 1700 K to room temperature after the current is cut off. This feature allows the device to effectively decompose by-products without causing thermal damage to the electrode material due to prolonged heating, and the original physicochemical properties of the catalyst can be effectively maintained. Since the entire regeneration process is carried out in an inert atmosphere, the regeneration unit can withstand tens of thousands of pulses.

Shanghai Qiguang Industry&Trade Co.

ShanghaiQiguangIndustry&TradeCo.,Ltd.

Technical index

Catalyst BDMA

Pack complete, pack lightly and unpack lightly.

Store in a cool, ventilated warehouse, protected from moisture, light, sealed and away from fire and heat sources.

Equipped with the appropriate variety and quantity of fire-fighting equipment.

The storage area should be equipped with leakage emergency treatment equipment and suitable shelter materials.

Shanghai Qiguang Industry & Trade Co.

Shanghai Qiguang Industry & Trade Co., Ltd.

Catalyst QGCAT 904

Pack well and pack lightly.

Store in a cool, ventilated warehouse, protected from moisture, light, airtight and away from fire and heat sources.

Equipped with appropriate types and quantities of fire-fighting equipment.

The storage area should be equipped with leak emergency treatment equipment and suitable shelter materials

About Qiguang

Qiguang Group is a polyurethane catalyst group with one-stop production, operation and sales. As a pioneer of polyurethane catalysts at home and abroad, it has recently launched a series of new products and has not only set up dozens of offices in China, but also set up branches in Taipei, Taiwan, Tokyo, Japan, Kuala Lumpur, Malaysia, Bangkok, Thailand, Ho Chi Minh and Hanoi, Vietnam to further improve its service system.

Qiguang Group is a production, management and sales of a one-stop polyurethane catalyst enterprise. Not only has there been dozens of offices in the country, but also branches have been Not only has there been dozens of offices in the country, but also branches have been established in Taipei, Taiwan, Tokyo, Kuala Lumpur, Malaysia, Bangkok, Thailand, Ho Chi Minh, Vietnam, and Hanoi.