As an important ingredient of nylon 66, what are the main production processes of the aridium。
Industrialized methods of production, which are classified according to the processes used for the production of adiazine, are currently three main methods: acrylic electrolysis, acrylate and cyanide. In addition, tori japan has developed the hydrolysis of acetamide for the regenerative use of acetamide wastes, but due to the lack of suitable raw materials, production capacity is extremely limited and products are used only for downstream products of its companies。
I. Butadiene act
The act could be further broken down by process route into cyanide butadiene, direct cyanide of butadiene, and butadiene alkyl。
(1) cyanide butadiene chloride
The butadiene chlorination act, also known as the two-part act, was developed by dubong in the early 1960s. The first is a co-reaction of butadiene, chlorine gas, with a product of 1,4-dichloro-2-butane; the second is a substitute reaction of 1,4-dichloro-2-butane, sodium cyanide, with a product of 1,4-dicycyanylbutane. This was followed by the development of diazine by the catalytic effect of rainey-ni。
The aridium preparation process involves more reactions. In view of the complexity, corrosiveness, investment and consumption of large quantities of chlorine and hydrocyanic acid, the response participation is highly toxic and environmentally sound management of safety has been phased out。
(2) direct cyanide of butadiene
In the early 1970s, dupont developed a non-chlorine direct cyanide method for the production of diazine, which reacts directly with hydrocyanic acid under catalysts and isomerization and secondary hydrocyanide into the generation of diazine。
The process routes for the butadiene hydrocyanide method are as follows. Phase i: butadiene is added to hcn by nickel catalysts to produce 2-methyl-3-butylonitrile (2m3bn) and 3-peneline (3pn); 2m3bn isomeric reaction to 3pns by nickel catalysts. Second stage: 3pn isomers are constructed into caylene: 4-pentane (4pn) followed by 4pn and hcn into ann and by-product 2-methyl-pentazine (mgn), a reaction requiring nickel catalysts and louisic acid aids, with high requirements for catalyst activity, which is a step in the overall response。
First, secondary hydrocyanide uses as a catalyst a combination of phosphorus-containing formulations and zero-price ni. In general, by ni
P (oarch3)3
4 and ni4。
The development of high-activity and selective high-performance catalysts is central to the butadiene cyanide process. In the first-level hydrogen cyanide response, there is still room for increased linear selectivity of catalysts, with the development of “one-step” high-activity and 3pn-selective catalysts to enhance the economy of processes. In addition, secondary hydrogen cyanide reaction is a rapid step in the overall process, requiring a high degree of catalyst activity, and the existing catalyst activity and ann selectivity need to continue to increase. The catalysts selected for this process can be divided into single- and double-compost catalysts. Due to the advantages of spatial and electronic effects, bidents have a large tolman cone, a highly stable synthetic catalyst, excellent reactive activity and linear selectivity, and have long been the focus of research. In the process of synthesis of catalysts, commercial purchases of high-activity nickel powder, with simple, relatively cheap sources and easy to magnify, can be attempted in response to the expensive availability of existing metal sources。
The technical difficulties of butadiene law are more dispersed. First, the compound catalysts needed for the response are heat-decompositionable, water is easily hydrolytic and later separation is more difficult to recover; second, hcn can easily reduce catalyst activity and hcn self-assembly can jam pipes; and, in addition, there are more congeners in the final reaction, similar boiling points, complex systems and high levels of purity. These technical problems can lead to lower yields and higher unit costs。
Direct cyanide, compared to chlorination, can effectively reduce the use and cost of raw materials for production and save energy consumption. The act is characterized by low cost of raw materials, non-pollution, high product quality and harvest rate, short process routes and relatively low investment. The act is the most advanced of the technologies for the production of diazine, which are now industrialized, and suitable for large-scale industrial production. It is for this reason that the capacity of inveida, which currently holds the technology, has always been absolute worldwide. However, the method was technically difficult and required a combination of hydrogen cyanide production plants, which required a higher level of investment and production scale than had been the case in the past with the massive industrialization of only invida and basff. In july 2022, china's chemical skyrocketing new material, niron project, was successfully launched and became the world's third company in possession of the butadiene method for the production of diazole, completely breaking the “calculated neck” situation in the country。
(3) butadiene ethylene ethylene glycolide
On 20 december 2019, a team of professor matthias beller of the rostock institute of the university of albert einstein, germany, reported on a new pd-based co-catalyst and its associated process for the one-step tributyltin gillification and its esters, the results of which represented a major breakthrough in the technology of butadiene ethylene sylvanication and its subsequent preparation for the diazine laboratory. In the country, a mid-temporal test of the butadiene ethylene thallyl radicalization preparation is also advancing。
The procedural step of the act is that butadiene reacts first with carbon monoxide and methanol by acting as a catalyst, producing a total of 1,6-hexadiate, and then, by acting as a catalyst, is ammonia dehydrated and eventually synthesized with diazine. By-product methanol, which returns to the system as feedstock, has the advantage of not using highly toxic hydrocyanic acid as feedstock compared to previous butadiene hydrocyanide methods, such as material safety, simple reaction processes, safe cleaning, product spurification, high feedstock conversion, product selectivity and separation. However, the act also had many shortcomings, such as low catalyst activity, low production of targeted products and low selectivity, which made industrialization difficult。
Aminolysis-dehydration in the process is not a critical step, nor is it technically complex, and the most difficult step is that of diethylene diethylene diethylene. The response process has complex response networks resulting from regional isomer gillification and isomerization, and the ideal catalytic process is to introduce the two molecules' co into both ends of the butadiene, with two continuous and non-selective diaphragms. Basement obtains a target product with an anthylene acid as an intermediate. The actual reaction process usually results in another group of non-reactive c=c double-key isomerization after monogismization, which produces by-products of the chain when further gillification occurs; in addition, the system is accompanied by other by-reaction processes, such as hydroxane oxide and alkyl polymerization, resulting in a generally less selective response。
The world-renowned petrochemical industries, including basif, dubun, shell and chinese petrochemicals, have made extensive attempts on this route, but all face low catalyst activity and low production, selectivity and industrialization of targeted products。
After many years of effort, the team of professor matthias beller adopted the design of a bidentic formulation replaced by a gill radical, which, in conjunction with gillium, is based on a step-by-step diethylene synthesis using 1,3-butadiene, carbon monoxide and butanol as feedstock synthesis diethylene, with a selective 97 per cent and an atomic economy of 100 per cent, with an unprecedented level of reaction. The catalytic system is highly active, selective and universal, and addresses the issue of selectivity and serious side-responses in the past of bi-butadiene alkylization. The process, which does not require the addition of nitrates, has achieved a new breakthrough in the legal phase of diethylene biethylene. The follow-up study will be based on the laboratory's short-term test to verify the long-term cyclical stability, activity and selectivity of catalysts under magnifying process conditions, with a view to establishing a solid foundation for the scale application of butadiene thylene glycol。
Ii. Acrylic diazole
(1) electrolytic ii
The acrylic electrolyte diformation method was first introduced by boz in the 1960s, then led by monsanto, united states, in industrial production in the 1960s and evolved from membrane to membrane-free electrolysis。
The diaphragm method was divided into solution and emulsion, which was initially used by monsanto, and was developed shortly after that time by japan amalgamation. At present, foreign firms with the technology for the production of this diazine include the japanese company xueto, the united states company cheonan and the german company basff. These companies produce acrylic feedstocks for adiazine, which are self-produced and are available through ammonia oxidation。
The reaction process of acrylene in cathode 2 condensation to acrylic diazine can be completed one step at a time, but it has high operational requirements. The selection of electrode materials, the formulation of electrolyte, the temperature of electrolytics during the reaction, the input concentration of acrylic acrylene, current density, and changes in the acidity of the solution have an impact on the selective response。
The reaction of acrylic hydrate dioxin is occurring in cathodes, and in order to avoid the normal conduct of large amounts of hydrogen-dialysis damage, it is necessary to select hydrogen perturbation high-level materials as cathodes, such as graphite (c), lead (pb) and cadmium (cd), all of which display good selectivity at low solubility levels of acrylene; lead is a commonly used cathode material with a wide range of sources and a preferred choice as a cathode material for electrosizing acoustic diazole; cadmium is easily electroplated on carbon steel to form a bipolar electrode, and its yield and current efficiency at high current density is better than that of lead, so that cadmium is the best option for cathode material in the pursuit of production。
Since the anodes occur with an oxygen-decomposition reaction, the choice of low-oxygen peroxide metal can reduce the oxidation of organic matter, such as pure iron, iron alloys (low carbon steel, carbon steel, low alloy steel, stainless steel, nickel steel, etc.). Stainless steel is the ideal material for the consumption and corrosivity requirements of the anodes, but carbon steel is more appropriate for economic reasons。
In addition to increasing the conductivity of electrolytic fluids as electrolytics and increasing the solubility of acrylic aluminum, the dysentery salt has significantly increased its yield and current efficiency, resulting in a sharp increase to 90 per cent of its yield and current efficiency. The choice of dyslexium salt is the key to the industrial production of electrolytic diammonium。
In addition, sulfurized styrene anion exchange resin is used as a diaphragm separation of the anode and cathode regions, with rare sulphate in the anode, with acrylic solutions using acrylic salts as electrolyte, and with the electrolysis of diazole, known as solution。
This was followed by an improvement in cathode fluids by the acrylic emulsifier, which is known as the emulsion method, with a small amount of emulsifier, i. E. Acrylic acrylic. The emulsion method has the following advantages compared to the solution method: the product is an emulsion liquid, which can be more easily separated without solvent extraction, followed by simple treatment and lower production and investment costs。
Both solution and emulsion methods are subject to membrane electrolysis by both cathode and anode circuits and anion exchange membranes。
After acrylic reacts only in the cathodes and does not interfere with the anode reaction, the belgian union chemical corporation has taken the lead in removing diaphragms, developing direct electrolytic dipolymers, using electrolytics as emulsions, preservatives as sodium hexamethyl phosphate, graphite in the cathode and magnets in the anode. In addition, basif uses a special cavity pyrolytic cell, anode materials uses graphite plating pbo2, cathode materials uses graphite, and diagonals are also eliminated. Low energy consumption and high product yields from the membrane-free method are the main trends in the electrolytic dimulgation of acrylene。
Acrylic electrolysis has the advantage of small pollution, short process, low investment, flexible construction, a single variety of raw materials from a wide range of sources, relatively simple technology, and easier to manage production, with a lower toxicity, a lower safety risk factor, a single variety and a wide range of sources compared to butadiene-based hydrocyanic acid. However, there are economic disadvantages due to the high price of acrylene, the high energy consumption of electrolytics, the high risk of entanglements and the small size of single lines. Therefore, increasing the conversion rate of acrylene, reducing single acrylic consumption and exploiting the potential to reduce electricity consumption is the main thrust of the technology route。
(2) catalysing the second conference
The reaction equations for acrylic dipolymerization are as follows (in the case of acoustic catalysts):
Figure response equations for acrylic catalytic dipolymerization
Depending on the type of catalyst, it can be divided into the catalyzed method, the catalyze method and other metallic catalytic methods。
Since the 1970s, the triple metal catalytic ii has received industry attention. Transitional metal catalytic responses have the advantages of selectivity, high yield rates and moderate process conditions, with wide applications in the fields of organic synthesis, drug synthesis and industrial production. In addition, available studies have shown that some thorium compounds can also act as catalysts for acrylic diazole, providing a more environmentally friendly process route for the synthesis of diazole. The act has the advantage of low energy consumption, low installation requirements, etc. Compared to the acrylic electrolytes, but there are also shortcomings such as the complexity of the catalytic system and the loss of life, which can result in large quantities of waste, which have not yet been industrialization。
Iii. Catalysing of adipic acid
The act of catalysing adipic acid was developed by the french company rona planck in the late 1960s, followed by the industrialization of the basif company, the latisi chemical plant and the china liaonization four plant (currently china oil liayang petroleum fibres ltd.). There are mainly liquid and gas phase pathways, based on essentially the same principles, with phosphate or phosphate as catalysts, and adipic acid and ammonia reaction at a certain temperature and pressure, with coarse diazole, refined to the product. The liquid phase method, although lower than the gas phase rate, does not replace the liquid phase method due to the long gas phase reaction process, high reaction temperature and high energy consumption。
(1) liquid phase law
The adipic acid, ammonia mixed into the reactor, reacts with a catalyst to produce diazine. The products of the two phases of the gas flow into the gaseous separators, the gas phase enters the separation tower, where volatile products, ammonia, excess ammonia are extracted; the pyramid is produced as semi-acinide containing its diazine, which is usually used as diluent to react to increase the rate of its diazine; and the coarse diazine is extracted from the tower. Liquid phase entry membrane evaporation units from separators are also used as diluting agents after dehydration. Accompanied by further refinements, the product has been produced. The liquid phase method is divided into intermittent and continuous methods, and the process is more mature, but the product is of poor quality, impurities are higher and yields are low。
(2) gas phase law
The solid powder is dehydrated directly with the ammonia gas using high temperatures (350-420°c) and the resulting gas condensed liquid mixture of diazine and ammonia is separated and refined. Gas phase product quality and harvest rates have improved significantly compared to liquid phase. However, the gas phase method has the disadvantage of long production processes, high reaction temperatures and high energy consumption。
With the development of americium production processes, the acrylic acoustic accelerosis method has been phased out as the price of raw materials has risen and the competitive advantage has declined sharply. There are currently only a few enterprises in the country with greater adipic acid production capacity, such as mount hua and some in construction。
Source: nationalized new materials, alkyl and high downstream
