The method of producing cyclohexanone from benzene
The invention relates to the production of cyclohexanone by liquid-phase oxidation products of hydrogenation of benzene containing cyclohexene, nitrous oxide or its mixture with an inert gas. The content of cyclohexene in the products of hydrogenation of at least 0.5%. The oxidation is carried out at a temperature of 150-350oAnd pressure of nitrous oxide is 0.1 to 200 ATM. Preferably the reaction mixture at the stage of oxidation of the injected inert gas diluent, catalyst. The technical result - the high selectivity of the reaction, the explosion process. 13 C.p. f-crystals, 4 PL. The invention relates to a method for producing cyclohexanone, and more particularly to a method of its production by oxidation of nitrogen oxide selective hydrogenation products of benzene containing cyclohexen.Cyclohexanone is an intermediate product for the synthesis of-caprolactam and adipic acid, which are used for the production of polyamide materials nylon-6 and nylon-66. It is also widely used as a solvent of fats, dyes, natural and synthetic resins.The main method for industrial preparation of cyclohexanone is in liquid-phase oxidation of cyclohexane with oxygen Volta [U. S. Pat. 3530185, 1970, K. Pugi]. This forms a mixture of cyclohexanone and cyclohexanol in which the proportion of cyclohexanone is less than 50%.It is also possible the non-catalytic oxidation of cyclohexane by. In this case, the reaction mixture was added boric acid, which binds the resulting cyclohexanol in the form of ether, inhibiting in this way the formation of by-products [U. S. Pat. 3932513, 1976, J. L. Russell]. The disadvantage of both variants of the process is the significant drop in the selectivity of the reaction with increasing conversion of cyclohexane. To maintain the total selectivity to cyclohexanone and cyclohexanol at the level of 85-90% conversion per pass should not exceed 3-5%. This leads to high costs for the selection of products and unreacted cyclohexane.Cyclohexanone can be obtained by selective catalytic hydrogenation of phenol [U. S. Pat. 3076810, 1963, R. J. Duggan et. al; U.S. Pat. 4092360, 1978, Jan F. Van Peppen et. al]. However, this method is not widely used because of the high cost of phenol.Currently, the industrial synthesis of cyclohexene is carried out by selective hydrogenation of benzene with hydrogen in the technology of producing adipic acid, which is then used for the synthesis of Nai N 1, R. 4]:According to this scheme, the process of hydrogenation of benzene leading to a ruthenium catalyst at 120-180oAnd pressure of 30-100 ATM [M. Kono, Chem. Ind. (Japan), 1988, v. 41, R. 936]. When the conversion of benzene 50-60% selectivity for cyclohexene is 80%. The remaining 20% of benzene into cyclohexane. The resulting reaction mixture of benzene, cyclohexene and cyclohexane are divided into components. Unreacted benzene return to the beginning of the process, and cyclohexen subjected to hydration in a zeolite catalysts with the aim of turning in cyclohexanol. Next cyclohexanol oxidized to adipic acid.Scheme (I) includes two difficult stages, decreasing its effectiveness. One of these stages - separation of the reaction mixture obtained after hydrogenation of benzene. This difficulty is connected with the small difference in boiling points of benzene (80,1oC), cyclohexene (82,98oC), and cyclohexane (80,74oC). The second hard phase is the hydration of cyclohexene to cyclohexanol. Due to thermodynamic limitations, this stage is carried out at low conversions that require a significant investment on the selection of the product and recycling unreacted cyclohexene. In addition lyst [M. Misono, T. Inui, Catal.Today, 1999, v. 51, R. 369].According to the invention, cyclohexen, without separating from the products of hydrogenation, are oxidized to cyclohexanone. Because the boiling point of cyclohexanone (155,6o(C) differs from the boiling point of the other components of the mixture, its selection can easily be done by using known techniques, which opens up a new and effective way to obtain this valuable chemical product.A new method for producing cyclohexanone, in his inclusion in the technological scheme of adipic acid, which helps to eliminate the aforementioned difficult stage of the process and replace them with more simple and effective, as shown in the diagram (II).According to this scheme, at the first stage of the process is carried out by selective hydrogenation of benzene with hydrogen. In the hydrogenation of the formed reaction products, which is a mixture of cyclohexene, cyclohexane and unreacted benzene. Stage hydrogenation can be carried out, for example, according to patent firm Asahi using a Ru catalyst [U. S. Pat. 4734536, 1988, Nagahara et al.] or any other known method, which is the concentration of cyclohexene in obrotowe the components serves on stage liquid-phase oxidation of nitrous oxide, where cyclohexen selectively converted into cyclohexanone, without being involved in the reaction of benzene and cyclohexane. Because the boiling point of cyclohexanone (155,6o(C) differs from the boiling point of the other components of the mixture, its selection can be easily performed by using known methods. Thus obtained cyclohexanone next, using known techniques, can be oxidized to adipic acid, converted into a-caprolactam or used for another purpose.Benzene and cyclohexane after the separation of cyclohexanone can be used in several ways. In the case of separation of a mixture of benzene sent in the beginning of the process to the stage of hydrogenation. Cyclohexane can either be derived from the process or recycled to the stage of dehydrogenation to benzene. In another process variant, a mixture of benzene and cyclohexane can be directed to the stage dehydrogenation without separation.Technological scheme (II) is more effective and has a number of advantages compared with the scheme (I). Namely: 1) phase separation of a mixture of benzene - cyclohexane - cyclohexane changed to a lighter stage of separation of the mixture benzene - cyclohexanone - cyclog is of cyclohexene, which has no thermodynamic restrictions and may be held to a deep degree of conversion; 3) cyclohexanone obtained instead of cyclohexanol, makes technology more flexible and allows you to send it as a synthesis of adipic acid and synthesis-caprolactam.Selective oxidation of cyclohexene, in the composition of the products of hydrogenation of benzene is a key stage of the technological scheme (II). The oxidation products of the hydrogenation can be carried out in a wide range of conditions both in static and flow-through reactor, which may be made of steel, titanium or other suitable material. This can be used all known technological methods that increase the efficiency of gas-liquid reactions.In the case of a static variant, the reaction mixture obtained at the stage of hydrogenation of benzene is loaded into the autoclave in such quantity that when the temperature of the reaction she was present as a liquid phase. Then served nitrous oxide or a mixture thereof with an inert gas and increase the pressure to a predetermined value. The concentration of inert gas in the mixture with nitrous oxide selected so that it does not exceed 99%. Cclu carried out at a temperature of 150-350oWith within the specified time, which may vary from several minutes to several tens hours. If necessary, to ensure a deeper conversion of cyclohexene, the gas phase is replaced by a new portion of the nitrous oxide. In the case of incomplete conversion of nitrous oxide it in the composition of the recirculating gases can be reused for the reaction.The oxidation reaction of cyclohexene with high speed proceeds without a catalyst, although it may also be carried out in the presence of a catalyst.The proposed method of producing cyclohexanone does not imply high purity nitrous oxide. Nitrous oxide can be used both in pure form and mixed with various gases, not having a harmful effect on process performance.It is known that nitrous oxide can form flammable mixtures with organic matter [g Panetier, A. Sicard, V Symposium on Combustion, 620 (1955); B. B. Brandt, L. A. Matov, A. I. Raslowsky, C. S. Khailov. Chem. prom. , 1960, 5, S. 67-73]. Intrinsically safe working conditions for the proposed method are provided by adding to the reaction mixture an inert gas reacts with N2O, for example nitrogen, argon, helium, carbon dioxide, etc. or is otnosheniya "organic components : nitrous oxide", the proportion of inert gas required to provide proof of work can be different and be created by a separate feeder. From the point of view of simplicity and maximum process safety it is advisable to have this dilution nitrous oxide inert gas to the reaction mixture was explosive when any content of organic components. This condition is satisfied if the content of N2O in a mixture with an inert gas is not more than 25%. Apply this mixture eliminates the occurrence of hazardous situations at all stages of the process.To reduce the explosion hazard in the reaction mixture can be added flame retardants, such as trifloromethyl, diperchlorate, dibromotetrafluoroethane etc.The essence of the invention is illustrated by the following examples.Examples 1-5 (table. 1) show the effect of temperature and time of oxidation of nitrogen oxide products of the hydrogenation of benzene.Example 1 To experiment using Parr reactor with a volume of 100 cm3made of stainless steel and equipped with a stirrer. The experience is carried out in two stages: 1) hydrogenation of benzene with hydrogen and 2) the oxidation products of the hydrogenation of nitrogen oxide.Per the t 0.2 g Ru catalyst, 20 ml of distilled water and 0.85 grams of zinc sulfate ZnSO47H2O. After the salt has dissolved in the reactor are added 50 ml of benzene, rinsed with hydrogen and install a pressure of 25 ATM. Then the reactor is heated to 150oWith, bring a hydrogen pressure of 50 ATM and include the stirrer. After 60 minutes of reaction, the reactor is cooled and determine the composition of the obtained reaction mixture. The hydrogenation products contain 15% benzene, 30% of cyclohexene and 55% of cyclohexane.For carrying out the second stage of the obtained products of hydrogenation in the volume of 33 ml is loaded into the reactor, connected to a metal cylinder containing nitrous oxide. After purging the reactor set pressure of nitrous oxide 25 ATM and the reactor heated to a temperature of 250oC. the Reaction are within 5 hours After the reaction, the reactor is cooled to room temperature, measure pressure and analyze the final composition of the gas and liquid phases by the methods of gas chromatography and gas chromatography / mass spectrometry. According to the analysis, oxidation is subjected only cyclohexen, which is converted into cyclohexanone. Benzene and cyclohexane participate in the reaction are not accepted. From the obtained data to calculate the conversion of cyclohexene (X) and CE CoCyEN- initial concentration of cyclohexene; CCyONthe concentration of cyclohexanone in the reaction products;Cside- total concentration of by-products. In the case of large conversion value X can be calculated also by the difference between the initial and final concentrations of cyclohexene:
Example 2 same as example 1 with the difference that the reaction of the oxidation products of hydrogenation of benzene is carried out at 240oWith in 12 hours.Example 3 same as example 1 with the difference that the reaction of the oxidation products of hydrogenation of benzene is carried out at 150oC for 20 hours.Example 4 same as example 1 with the difference that the reaction of the oxidation products of hydrogenation of benzene is carried out at a temperature of 198oWith in 12 hours.Example 5 same as example 1 with the difference that the reaction of the oxidation products of hydrogenation of benzene is carried out at 220oWith in 12 hours.Example 6
This example is comparative. The experience carried out analogously to example 1 with the difference that at the stage of oxidation in the reactor load 4 ml hydrogenation products of benzene. Under such load all organic components in the reaction conditions nah what these conditions, the reaction in the gas phase is hardly taking place.Examples 7-8
These examples in comparison with examples 4 and 5 demonstrate the effect of the concentration of nitrous oxide in the process indicators (table. 2). The concentration of nitrous oxide in the reaction mixture is set by the size of its initial pressure at room temperature,.Example 7 same as example 4 with the difference that if the reaction of the oxidation products of the hydrogenation of benzene initial pressure of nitrous oxide set of 40 ATM.Example 8 is similar to example 5 with the difference that if the reaction of the oxidation products of the hydrogenation of benzene initial pressure of nitrous oxide ask 10 ATM.Examples 9-11, the results of which are given in table. 3 show the possibility of oxidation products of hydrogenation of benzene with nitrous oxide in the presence of a catalyst.Example 9 same as example 1 with the difference that the oxidation is carried out in the presence of 0.2 g of the zeolite catalyst FeZSM-5. Zeolite (SiO2/Al2O3=150, 0.56 wt.% Fe) prepared by hydrothermal synthesis method with the introduction of iron in the original gel in the form FeCl3. After burning a template and translation of the zeolite in the H form the sample calcined in air at 550oC and then subjected thermoprotei activation at 650o2O3/SiO2(2.8 wt.% Fe2O3). The catalyst is prepared by impregnation of SiO2solution Fl3, dried at 110oC and calcined in air at 500oC for 2 hExample 11 same as example 10 with the exception that the oxidation is carried out in the presence of 0.3 g of Rh/ZrO2(1 wt.% Rh). The catalyst is prepared by impregnation of ZrO2a solution of Rh(NO3)3, dried at 110oC and calcined in air at 500oC for 2 hExamples 12-18 are shown in table. 4. These examples show the possibility of oxidation products of hydrogenation of benzene using dilute mixtures of nitrous oxide.Example 12 same as example 1 with the difference that the oxidation products of hydrogenation, instead of pure nitrous oxide in the reactor serves its mixture with an inert gas - nitrogen, in which the concentration of N2O is 70%. The initial pressure in the reactor (R0) set 45 ATM.Example 13 same as example 12 with the difference that the concentration of N2O in a mixture with nitrogen is 20%. The experience carried out at 220oWith in 12 hours.Example 14 same as example 13 with the difference that the initial pressure in the reactor was set to 80 ATM.Example 15 same as example 13 with otlichie 40 ATM.Example 16 same as example 13 with the difference that as the inert gas instead of nitrogen gas used argon, and the concentration of N2O in a mixture with Hypertension is 50%. The initial pressure in the reactor was set to 30 ATM.Example 17 is similar to example 16 with the difference that instead of argon using carbon dioxide.Example 18 is similar to example 16 with the difference that the concentration of N2O in a mixture with argon is 1%. The initial pressure of the mixture in the reactor was set to 200 ATM. The experience carried out at 250oC for 5 hours.Examples 12-18 show that the oxidation products of hydrogenation with high selectivity occurs when using nitrous oxide, diluted with an inert gas. The content of N2O in an inert gas may vary widely, including in the area of concentration of nitrous oxide 25% or less, which excludes the possibility of hazardous situations under any mixes with the products of hydrogenation. As examples 13 and 14, the oxidation reaction of cyclohexene to cyclohexanone in this area proceeds with high efficiency.Example 19
This example shows the possibility of oxidation products of hydrogenation with the use of recirculating gases.Example 19 similar pria, formed after the oxidation products of the hydrogenation according to example 4. Then the reactor add pure nitrous oxide, bringing the total pressure of 25 ATM. The experience carried out at 240oWith in 12 hours. Experience the conversion of cyclohexene was 44.7% with a selectivity 94,1%.In the present invention proposes a new method of producing cyclohexanone, based on the reaction of liquid-phase oxidation products of hydrogenation of benzene containing cyclohexene, nitrous oxide or its mixture with an inert gas. The process provides a high selectivity of the reaction, the explosion of work and is perspektivnym for industrial applications.
1. The method of producing cyclohexanone from benzene, characterized in that it is carried out by hydrogenation of benzene, providing concentration of cyclohexene in the products of hydrogenation of at least 0.5%, with subsequent liquid-phase oxidation by nitrous oxide hydrogenation products of benzene containing cyclohexane, at a temperature of 150-350oAnd pressure of nitrous oxide is 0.1 to 200 ATM.2. The method according to any of the p. 1, characterized in that the hydrogenation products of benzene serves on the stage of oxidation of nitrogen oxide without radium oxidation of nitrous oxide after their partial separation.4. The method according to any of paragraphs.1-3, characterized in that the reaction mixture at the stage of oxidation of the injected inert gas diluent.5. The method according to any of paragraphs.1-4, characterized in that the concentration of inert gas in the reaction mixture does not exceed 99%.6. The method according to any of paragraphs.1-5, characterized in that the concentration of the inert gas is selected so as to exclude the possibility of formation of explosive compositions at each stage of the process.7. The method according to any of paragraphs.1-6, characterized in that the oxidation products of the hydrogenation is carried out at a temperature 150-199oAnd pressure of nitrous oxide is 0.1 to 200 ATM.8. The method according to any of paragraphs.1-7, characterized in that the oxidation products of the hydrogenation is carried out at a temperature of 150-350oAnd pressure of nitrous oxide is 0.1 to 20 ATM.9. The method according to any of paragraphs.1-8, characterized in that the oxidation products of the hydrogenation is carried out in the presence of a catalyst.10. The method according to any of paragraphs.1-9, characterized in that the nitrogen oxide contains traces of other gases without impairing the performance of the process.11. The method according to any of paragraphs.1-10, characterized in that the oxidation reaction is carried out in a static or flow-through reactor.12. The method according to any of paragraphs.1-11, characterized in that disa fact, what we get cyclohexanone is used to produce adipic acid.14. The method according to any of paragraphs.1-13, characterized in that the resulting cyclohexanone is used for-caprolactam.
FIELD: organic chemistry, in particular production of carbonyl compounds such as aldehydes and ketones.
SUBSTANCE: claimed method includes reaction of nitrous oxide with alkenes in presence of inert gas as diluent. Reaction is carried out in gas phase at 401-700°C and under pressure of 2-300 atm. Target compounds represent value intermediates for precise and base organic synthesis.
EFFECT: method of high selectivity in relation to target products and improved explosion proofing.
5 cl, 1 tbl, 14 ex
FIELD: organic chemistry, chemical technology, catalysts.
SUBSTANCE: invention relates to catalytic decomposition of organic hydroperoxides representing important compounds on organic synthesis. Decomposition of cycloalkyl hydroperoxides comprising from 6 to 12 carbon atoms results to formation a mixture of corresponding alcohols and ketones. Process is carried out in the presence of a solvent (alkane, halogen-containing hydrocarbon) at temperature from 20°C to 200°C. Catalyst comprises ruthenium as a catalytically active metal added to a solid carrier chosen from the following group: carbon prepared by pyrolysis of acetylene and metal oxides chosen from the group comprising zirconium, aluminum, lanthanum and manganese. The amount of catalyst expressed as the mole percents of ruthenium to the amount of moles of hydroperoxide to be decomposed is from 0.0001% to 20%. Preferably, the catalyst comprises one additional rare-earth element as a component of alloy. The carrier represents, as a rule, metal oxide with high specific surface above 10 m2/g but preferably, above 100 m2/g that is resistant against oxidation. The hydroperoxide concentration is in the range from 1 to 80 wt.-% with respect to the solution mass. Preferably, hydroperoxide represents cyclohexyl, cyclododecyl, tetraline, ethyl benzene or pinane hydroperoxide and hydrocarbon used in preparing the parent hydroperoxide is used as a solvent. Invention provides the development of the modified catalyst enhancing conversion and selectivity in decomposition of hydroperoxides.
EFFECT: improved method for decomposition.
8 cl, 24 ex
FIELD: organic chemistry, chemical technology.
SUBSTANCE: invention relates to an improved method for synthesis of 2,6-di-(3,3',5,5'-di-tert.-butyl-4,4'-oxybenzyl)-cyclohexane-1-one used as a stabilizing agent of polyolefins and low-unsaturated carbon=chain rubbers. Method involves interaction of cyclohexanone with N,N-dimethyl-(3,5-di-tert.-butyl-4-oxybenzyl)amine in the ratio = (1-1.2):2, respectively, and process is carried out at temperature 125-145°C up to ceasing isolation of dimethylamine. Method provides simplifying technology and preparing the end product with the yield 61-85.4%.
EFFECT: improved method of synthesis.
12 tbl, 23 ex
FIELD: organic chemistry, chemical technology.
SUBSTANCE: invention relates to a method for synthesis of 3-bromoadamantyl-1-alkyl(aryl)-ketones of the general formula: , wherein that can be used as intermediate substances for synthesis of some biologically active compounds. Method involves interaction of 1,3-dehydroadamantane with α-bromoketones of the following order: α-bromoacetone, α-bromoacetophenone, α-bromocyclohexanone in the mole ratio of reagents = 1:(2-3), respectively, in absolute diethyl ether medium, at temperature 34-40°C for 3-4 h. Method provides preparing the claimed compounds with high yield.
EFFECT: improved method of synthesis.
SUBSTANCE: present invention relates to a method of continuous oxidation of saturated cyclic hydrocarbons using oxygen, into a mixture of hydroperoxide, alcohol and ketones. The method involves feeding into the lower part of a column and in parallel flow, a stream of oxidisable liquid hydrocarbon and a gas stream containing oxygen, and degassing the liquid phase in the upper part of the column by forming a gas dome and extraction of the degassed liquid phase. The gas containing oxygen is let into different compartments of the column, and into the dome and/or liquid phase at the level of the degassing zone, or directly above. A stream of non-oxidising gas with output sufficient for maintaining concentration of oxygen in the gas layer at the level of volume concentration, less than or equal to the upper limiting concentration of oxygen is supplied.
EFFECT: possibility of implementing a method with high selectivity on an explosion safe level.
9 cl, 1 dwg, 1 ex
SUBSTANCE: invention relates to a method of producing cyclohexanone from cyclohexane, involving the following stages: oxidation of cyclohexane to hydroperoxide of cycohexyl with oxygen in the absence of a catalyst, purification of the reaction medium by washing with water, decomposition of hydroperoxide of cycohexyl to cyclohexanol and cyclohexanone in the presence of a catalyst, extraction of the cyclohexanol/cyclohexanone mixture for separating unreacted cyclohexane and separation of products with boiling point higher than that of the cyclohexanol/cyclohexanone mixture, dehydrogenating cyclohexanol contained in the cyclohexanol/cyclohexanone mixture, in the presence of a dehydrogenation catalyst, distillation of the obtained mixture so as to obtain first run (F1) at the first stage, containing compounds with boiling point lower than that of cyclohexanone, and a last run (Q1) and distillation of the last run (Q1) to obtain a first run (F2) at the second stage, formed from cyclohexanone, and a last run (Q2).
EFFECT: obtaining highly pure cyclohexanone, suitable for use as raw material for synthesis of ε-caprolactam.
6 cl, 1 dwg, 3 ex
SUBSTANCE: method involves preparation of a reaction mixture at room temperature consisting of the alcohol to be oxidised, sodium bicarbonate, an organic solvent and a nitroxyl radical. Electrolysis is carried out on platinum electrodes with current of 1 A and temperature of 20-25°C. Potassium iodide is added to the reaction mixture. The organic solvent used is dichloromethane and the nitroxyl radical used is 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl of formula: with ratio of alcohol to nitroxyl radical equal to 10:1.
EFFECT: invention ensures high output of end products a within short period of time and less expenses on electricity using a high-technology method.
SUBSTANCE: invention relates to a method of preparing a mixture of cyclohexanol and cyclohexanone which are intermediate products in production of polyamides nylon-6 and nylon-6.6. The method is realised at high temperature and high pressure and involves the following successive cycles: oxidation of cyclohexane - decomposition of cyclohexylhydroperoxide, wherein oxidation of cyclohexane and decomposition of cyclohexylhydroperoxide are carried out in separate series-connected reactors without intermediate separation of the aqueous phase, whereby in each separate cycle, cyclohexane is oxidised with air or an oxygen-containing gas in liquid phase in the absence of a catalyst until conversion of cyclohexane of not more than 1.5 mol %, and the cyclohexylhydroperoxide formed during oxidation of cyclohexane is decomposed on a heterogeneous catalyst in a separate reactor until conversion of not less than 90 mol %.
EFFECT: method increases overall selectivity of converting cyclohexane to cyclohexanone and cyclohexanol and also considerably reduces formation of by-products.
9 cl, 19 ex, 2 tbl, 1 dwg
SUBSTANCE: method involves a step for oxidising cyclohexane to obtain cyclohexyl hydroperoxide, a step for catalytic decomposition of cyclohexyl hydroperoxide on a heterogeneous catalyst to obtain a mixture of cyclohexanol and cyclohexanone and a step for distilling cyclohexane, carried out at high temperature and pressure. Said steps form a single circulation loop in which the reaction mixture is circulated through transfer of cyclohexane vapour from the boiler of the distillation apparatus into an oxidation reactor, as well as due to subsequent spontaneous overflow under gravitational forces of the liquid reaction mixture from the oxidation reactor to a decomposition reactor and then into the boiler of the distillation apparatus. The cyclohexane oxidation reactor lies over the cyclohexyl hydroperoxide decomposition reactor which is on the same level as or below the level of the boiler of the distillation apparatus. Conversion of cyclohexane in the oxidation zone is not more than 1.0 mol % and conversion of cyclohexyl hydroperoxide in the decomposition zone is not less than 90.0 mol %.
EFFECT: high selectivity of the cyclohexane oxidation process.
8 cl, 1 tbl, 1 dwg, 15 ex
FIELD: process engineering.
SUBSTANCE: invention relates to catalyst for dehydration of cyclohexanol to cyclohexane and to method of its production. Proposed catalyst comprises the following components in wt %: calcium carbonate - 16.4-37.0, graphite - 1.0-3.0, and zinc oxide making the rest. Proposed method comprises preparing reaction mix of previously mentioned composition containing sources of zinc oxide and calcium carbonate, moulding, drying, and calcinating. Note here that said mix comprises the following components in wt %: calcium carbonate - 12.4-29.8, carboxymethylcellulose or methylcellulose - 0.1-1.0, and base zinc carbonate making the rest, while graphite is added into amounts sufficient for production of said catalyst.
EFFECT: higher strength, lower costs, simplified production, reduced harmful effects.
3 cl, 2 tbl, 2 ex