CZ200117A3 - Process for preparing aliphatic dibasic acid and dinitrogen oxide - Google Patents

Abstract

Aliphatic dibasic acid and nitrous oxide are prepared as follows: aliphatic dibasic acid prepared by oxidation of a hydroxylated aromatic compound nitrous oxide to form an aliphatic dibasic acid and an oxide nitrous is prepared by reducing the mixture of gas stream containing Nox and ammonia used in aliphatic formation dibasic acids.

Description

Process for preparing aliphatic dibasic acid and nitrous oxide

Technical field

The invention relates to a process for the preparation of nitrous oxide. The invention relates to the use of nitrous oxide produced for the hydroxylation of aromatic compounds. The invention also relates to the purification of nitrous oxide-containing gas streams and subsequent use in the above-mentioned hydroxylation processes.

BACKGROUND OF THE INVENTION

Pure nitrous oxide (N2O) is used as a narcotic gas in medicine and as an oxidizing agent for various combustibles and as a cleaning agent in semiconductor manufacturing. Recently, a new use of nitrous oxide diluted with molecular nitrogen (as the most accessible inert gas) has been discovered. It is used as a mild oxidizing agent for the production of various hydroxylated hydrocarbons. However, the technology of this production imposes stringent requirements on the content of other strong oxidizing agents, such as oxygen, nitric oxide (NO) and nitrogen dioxide (NO2), which may be present in the nitrous oxide admixture.

A well known process for preparing nitrous oxide is by decomposing the melt of ammonium nitrate (NH 4 NO 3) at 220 to 250 ° C (see USSR 1097556). However, this procedure is difficult to control due to the high probability of spontaneous decomposition. Thus, it is not possible to easily construct high capacity units and thus produce large scale nitrous oxide. In addition, ammonium nitrate is quite expensive, which increases the cost of producing nitrous oxide. In addition, a special nitrogen diluted nitrous oxide source is needed.

There are also methods for the preparation of nitrous oxide based on the selective oxidation of ammonia (NH3) with molecular oxygen (O2) over various metal oxide catalysts at 200 to 500 ° C at pressures up to 2.026 MPa. Since these methods use cheaper raw materials, the price of the product is lower. In addition, it is a safer method and allows large capacity production.

For example, according to the method for preparing nitrous oxide by selective oxidation of ammonia (Japanese Patent Application No. 46-33210), a reaction mixture of gases containing ammonia and molecular oxygen passes through the catalyst bed and reaction product, a mixture of gases containing nitrous oxide, nitrogen oxides, water vapor, molecular oxygen and molecular nitrogen is divided into two streams. One of the streams is returned to the feed of the reaction mixture and the other stream is subjected to separation processes to obtain pure nitrous oxide. The ammonia concentration in the process does not exceed 10 to 15 vol% in order to avoid an explosive range of ammonia-oxygen systems. The reaction product obtained, a mixture of gases, contains 99 9

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9 9 9 9 9 9 9 · 9 * 9 9 9 9 9 9 · · * considerable amounts of impurities such as nitric oxide, nitrogen oxides (eg NO _X ) and oxygen, which are stronger oxidizing agents than nitrous oxide and therefore not desirable in the production of hydroxylated hydrocarbons.

In another method (Japanese Patent Application No. 6-122505), a stream of ammonia, molecular oxygen, and water vapor reaction gas mixture passes through a catalyst bed to give a reaction product, a gas mixture containing nitrous oxide, molecular oxygen, passed ammonia, nitrogen oxides (ΝΟχ) and water vapor. Expired ammonia and water condense on a condenser and return to the feed reaction mixture. Thus, more than 50 vol% of water vapor is recycled from the reaction product after condensation. Such dilution of the reaction mixture with water vapor allows for higher selectivity to nitrous oxide and its higher concentration in the end product. The addition of water also makes the process safer by raising the lower limit of the explosive ammonia range.

The main disadvantage of this process is that a lot of energy is consumed for condensation by cooling and evaporating the ammonia solution, which increases the production cost of nitrous oxide. It is also clear that more than 50 vol% of water must be present in the reaction mixture for explosive safety purposes, which requires even more energy for condensation and evaporation. In order to reduce the content of nitrous oxide impurities in the final product of the method, the oxygen / ammonia volume ratio in the reaction mixture at the inlet to the highly selective CuO-MnOg catalyst bed is maintained between 0.5 to 1.5. When using other highly selective catalysts, this process does not give the desired results.

US Patents 5055623; Nos. 5001280 and 5110995, the subject matter of which is hereby incorporated herein, describe the hydroxylation of aromatic compounds to aromatic alcohols (e.g. phenol) using nitrous oxide. However, the price of nitrous oxide for such hydroxylation is cost-limiting compared to existing phenol production technology (for example, the cumene process as disclosed in the KirkOthmer Encyclopedia of Chemical Technology, 3rd Edition, Volume 17, John Wiley & Sons, 1982, pages 374-). 377).

In the preparation of dibasic acids, waste streams are generated which contain nitrous oxide, NO _X , CO 2, CO 2, N 2, low boiling organic compounds and other gases. To date, nitrous oxide from the waste streams of dibasic acids has not been obtained because of the excessive cost of separating and purifying nitrous oxide from the waste streams for applications other than high purity nitrous oxide for medical purposes. Currently, waste streams are either vented, destroyed or recycled to form nitric acid. Accordingly, the use of nitrous oxide from the waste streams of dibasic acids, including the hydroxylation of aromatic compounds, has not yet been envisaged.

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Thus, there is a need to provide a large-scale process for producing nitrous oxide, economically, safely, and with high yields and conversion values.

In addition, there is also a need for an economical process for commercially producing phenolic compounds while producing other desired chemical intermediates.

SUMMARY OF THE INVENTION

The present invention is a process for producing nitrous oxide while substantially reducing the content of nitrogen oxides (NO _x ) and oxygen in the final nitrous oxide product stream at a very low energy consumption utilizing ammonia oxidation.

The invention also relates to a process for the recovery and purification of nitrous oxide present in various NO _x containing gas streams by converting NO _X to nitrous oxide by oxidation of ammonia.

The invention relates to a process for producing aliphatic dibasic acids by hydroxylating an aromatic compound in a nitrous oxide reactor to form a phenolic compound that is reduced to form a cycloaliphatic ketone and / or alcohol compound which is oxidized to form an aliphatic dibasic compound and a nitrous oxide gas stream. which is processed into a stream of purified nitrous oxide gas, wherein the purified stream of nitrous oxide gas is recycled back to the reactor.

The invention also relates to a process for producing nitrous oxide from a gas stream containing NO _x into the reactor while supplying a reaction mixture comprising ammonia and a gas stream comprising NO _x and ammonia leads to oxidation and reduction of NO _X to form a product stream of nitrous oxide.

The invention relates to a process for producing an aliphatic dibasic acid (e.g., adipic, glutaric, succinic, oxalic, and the like) comprising hydroxylating an aromatic compound using nitrous oxide to form a phenolic compound, reducing the phenolic compound to form a cycloaliphatic ketone and / or alcohol compound, oxidizing cycloaliphatic ketone and / or alcohol compounds, to form an aliphatic dibasic acid and a nitrous oxide gas stream, treating the nitrous oxide gas stream to obtain a purified nitrous oxide gas stream, and recycling the purified nitrous oxide gas stream to a hydroxylation step.

Hydroxylation of the aromatic compounds is accomplished directly by oxidation of the aromatic nucleus using nitrous oxide over the zeolite catalyst as described in U.S. Patents 5,110,995, 5,672, 777 and 5,756,861, the disclosure of which is incorporated herein by reference in its entirety.

For example, a mixture of benzene and nitrous oxide is contacted with a catalyst in a reactor under conditions selected to oxidize benzene to phenol. The molar ratio of benzene to nitrous oxide in the mixture may be less than 0.5. The ratio of nitrous oxide to benzene may be low enough to allow 9 9 ·

99 99 99 99 999 provided at least 90% by volume of obtainable selectivity of the reaction of benzene with phenol. Obtainable selectivity ”means the minimum maximum selectivity of benzene to phenol obtainable under given reaction conditions and catalyst by reducing the molar ratio of nitrous oxide to benzene. When preferred catalysts are used at normal reaction temperatures, the selectivity obtainable is typically close to or at a molar ratio of nitrous oxide to benzene of about 0.1. In the reactor stream, unreacted benzene can be separated from the product by conventional separation techniques and recycled to the reactor.

The mixture of nitrous oxide, benzene and any inert gas used in the reactor (benzene-nitrous oxide reaction mixture) may contain at least 0.3 mol% nitrous oxide. Lower quantities tend to reduce productivity. By selecting the reactor ratios, the adiabatic temperature rise from the exothermic reaction can be reduced to 150 ° C or less. When this is done, the reaction can be carried out adiabatically, eliminating the use of costly heat exchange means without unnecessarily increasing the formation of unwanted by-products. Increasing the inert gas or benzene content for temperature control also makes the mixture less flammable.

The process will generally be carried out in a temperature range of 250 to 600 ° C. Higher temperatures can lead to undesirable formation of large amounts of by-products, while lower temperatures too slow the reaction rate with most catalysts. However, any temperature providing an acceptable rate of reaction can be used. Any catalyst effective for partial oxidation of benzene or substituted benzene to phenol or substituted phenol can be used.

For example, vanadium pentoxide or various zeolites may be used. Preferred catalysts include acidified ZSM-5 and ZSM-11 containing a catalytic amount of iron. Further, the productivity of the process can be increased by using zeolite which has been hydrothermally treated by exposure to water vapor in air at about 500 to 900 ° C for about 2 hours. Such an arrangement is described in U.S. Patent Application No. 08 / 419,361 filed April 10, 1995 and related. A description of this application is incorporated herein by reference.

The process will generally be performed to maximize selectivity for phenol (moles of phenol produced per mole of reacted benzene), to maximize selectivity of nitrous oxide for phenol (moles of phenol produced per mole of reacted nitrous oxide) to maximize productivity (phenol mass produced from unit time divided by catalyst mass) and the rate of catalyst activity loss was maximized. (The yield of nitrous oxide or benzene to phenol will usually be somewhat lower than selectivity due to system losses.) • 9 · «99 · 9 ··

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The primary benzene to phenol conversion reaction is accompanied by various side reactions including benzene to carbon conversion reaction, benzene to carbon dioxide and carbon monoxide conversion reaction, and benzene conversion reaction to various oxidized aromatics such as dihydroxybenzenes.

It is understood that the variants discussed above other than the proportions of the feed components are not independent. For example, increasing the temperature of the feed components increases the reactor exit temperature by increasing the reaction rate and nitrous oxide conversion. Also, the average nitrous oxide concentration in the reactor decreases due to higher conversion. The yield of nitrous oxide to phenol will depend on whether the benefit from a lower concentration of nitrous oxide is greater or less than the loss from a higher temperature. Similarly, productivity will depend on whether any reduction in selectivity is counterbalanced by an increase in nitrous oxide conversion.

The phenol obtained in the preceding reaction is hydrogenated to form a mixture of cyclohexanol and cyclohexanone (usually referred to as KA oil). Reactions of this type are well known, as shown in GB Patent Nos. 1,063,357, 1,257,607, 1,316,820, 1,471,854 and US Patent Nos. 3,932,514, 3,998,884, 4,053,524, 4,092,360, 4,162,267, 4,164,515, 4,200,553, 4,203,923, 4,283,560 and 4,272,326 incorporated herein. by this reference in its entirety.

In one embodiment, the KA oil is produced by selective hydrogenation of phenol in the vapor phase in the presence of a palladium-containing catalyst, characterized in that the reaction is carried out at a temperature between 100 and 200 ° C and in the presence of a catalyst containing 0.3 to 5 wt. The catalyst also contains between 2 and 60 wt% based on the total weight of the catalyst, the alkaline earth metal hydroxide.

Catalysts containing calcium hydroxide as an alkaline earth metal hydroxide have proven to be particularly effective.

The catalysts to which the invention relates are preferably produced by forming together the t-alumina and the alkaline earth metal hydroxide, then impregnating the shaped pellets or catalyst bodies with an aqueous palladium chloride solution or a palladium nitrate solution and then reducing it with hydrogen.

The process can be carried out continuously at a reaction temperature of between 120 and 170 ° C, either at atmospheric pressure or at elevated pressure, in such a way that the phenol and hydrogen vapors pass in a molar ratio from 1: 5 to 1:25 through the catalyst located in the reaction tubes. In this process, the phenol flow is maintained between 0.15 and 0.30 kg of phenol per liter of catalyst. The reaction product contains 92 to 96% cyclohexanone, 2 to 4% cyclohexanol and several percent unconverted phenol.

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The KA oil obtained above reacts with nitric acid to form adipic acid. Reactions of this type are known, for example, as shown in US Patent Nos. 4,423,018, 3,758,564, 3,7329,712 and 3,1146,592, the subject matter of which is incorporated herein by reference in its entirety. Such reactions give, in addition to the desired adipic acid, nitrous oxide, which is recycled to the benzene oxidation reaction. The nitrous oxide obtained in the reaction is often contaminated with more than 10 wt% NO _x . High levels of NO _X have been found to be detrimental to the reaction process. Therefore, the nitrous oxide recycle supplied to the reaction of benzene to phenol should contain no more than 2%, preferably no more than 1% and more preferably no more than 0.1 vol% NO _X. The desired purity of the recycle stream can be achieved by controlling the oxidation of the KA to minimize NO 2 formation and by diluting the recycle stream with very pure nitrous oxide. However, such a technique can be economically disadvantageous or impractical. It is therefore preferred to adjust the flow of gaseous nitrous oxide from adipic acid production process, to reduce the content of NO _X.

NO _X removal can be accomplished by any known method. Such procedures are described, for example, in U.S. Patent Nos. 3,689,212, 4,507,271, 5,030,436 and Japanese Patent Publications 5-139710, 7-122505 and 6-122507, the entire disclosure of which is incorporated herein by reference.

However, the method of the invention described below is particularly preferred. Not only is the process of the invention an excellent and economical way to generally remove odstraněníχ, it also produces the additional nitrous oxide required for the subsequent hydroxylation of benzene to phenol.

For example, the invention provides for the direct production of nitrous oxide with a limited content of nitrogen oxides and oxygen at low energy consumption.

One embodiment of the invention relates to a process for producing nitrous oxide by treating a stream of NO _x containing gases comprising supplying a reaction mixture containing ammonia and a stream of NO _x containing gases to a reactor and oxidizing ammonia and reducing NO _x to produce a stream of nitrous oxide product.

In one embodiment of the present invention can remove _NOx from the gas stream containing _NOx implemented separately from the production of nitric oxide or can be performed simultaneously with the production of nitrous oxide in the same reactor / process, as described herein. In addition, nitrous oxide production can be carried out separately from nitrous oxide production as a separate process.

According to another embodiment of the invention, a stream of the reaction gas mixture comprising molecular oxygen, molecular nitrogen, ammonia and water vapor is introduced into the catalyst bed for oxidizing the ammonia with oxygen. The selectivity of the catalyst with respect to nitrous oxide is not less than 80%. The gaseous reaction product formed in the bed contains mainly nitrous oxide, nitrogen and water vapor. At

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · A temperature higher than the condensation temperature of water (e.g. at 5 ° C to 450 ° C, preferably at 70 ° C to 330 ° C more preferably at 90 ° C to 150 ° C), part the gaseous reaction product (e.g. 25 to 89%) is then separated and returned to the reaction mixture stream. Optionally, a separate portion of the gaseous reaction product is mixed with air, ammonia and molecular nitrogen so that the molecular oxygen content remains between 1.0 to 20.0 vol%, preferably between 1.5 to 15.0 vol% and more preferably between 2 0 to 12.5% by volume. The ratio of ammonia to oxygen volume concentrations is 0.2 to 5.0, preferably 0.5 to 2.0 and more preferably 0.8 to 1.5. Nitrous oxide, which may contain nitrogen, is prepared by separation from the remainder of the product gas stream.

In another embodiment of the invention, the method is carried out as follows. First, a stream of gaseous reaction mixture is prepared in two steps. In a first step, the dust-free air is mixed with the above-mentioned separate and recycled portion of the gaseous product stream. In the second step, ammonia is added. Aqueous ammonia can also be used for this purpose (although ammonia can be added in any of these steps). Nitrogen may be added in one step to give a more dilute N ₂ O gas product. The dilute product may also contain inert impurities such as CO ₂ or argon. The flow rates for air, part of the product, ammonia and nitrogen are controlled such that the oxygen content of the reaction mixture stream remains between 1.0 to 20.0 vol%, preferably 1.5 to 15.0 vol%, and more preferably 2 0 to 12.5 vol.%, While the ratio of volume concentrations of ammonia to molecular oxygen is 0.2 to 5.0, preferably 0.5 to 2.0, and more preferably 0.8 to 1.5.

The gaseous stream of the reaction mixture is introduced into the oxidation catalyst bed. The composition of the catalyst for the oxidation of ammonia to nitrous oxide is MnO ₂ / Bi ₂ O ₃ / Al ₂ O ₃ or MnO ₂ / Bi ₂ O ₃ / Fe ₂ O ₃ or MnO ₂ or MnO ₂ / Bi ₂ O ₃ or MnO ₂ / CuO . The catalysts give the following reaction for the oxidation of ammonia to nitrous oxide

2NH ₃ + 2O ₂ = N ₂ O + 3 H ₂ O (I)

At the same time as reaction (I) in the catalyst bed, undesired reactions occur 2NH ₃ + 5 / 2O ₂ = 2NO + 3H ₂ O (II)

2NH ₃ + 3 / 2O ₂ = N ₂ + 3H ₂ O (III)

Reaction (II) gives nitrogen oxides NO _X , while reaction (III) reduces selectivity to the end product (N ₂ O). All of the above catalysts provide no less than 80% selectivity to nitrous oxide, an essential parameter for solving the problem. Only 0.3 to 3.0% of ammonia is oxidized by reaction (II). The catalyst is partially reduced by NO _x reactions

4NO + 4NH ₃ + O ₂ = 4N ₂ + 6H ₂ O (IV) φ φ φ φ φ φ · · · · · φ φ φ · · φ φ φ φ φ · φ φ φ φ φ φ φφφ φφ φφ ·· φφ φφ »

The oxidation of ammonia to nitrous oxide on the catalysts is carried out at 200 to 400 ° C. A large amount of heat is released during reactions (I) to (III). Thus, heat can be removed to control the temperature of the reactor. For example, when using a tubular reactor (with a catalyst loaded into the tubes) or an adiabatic multiple bed reactor (where the catalyst is organized into the tubes), heat may be removed between the beds, or when using a fluidized bed catalyst with a heat exchanger installed in the bed. .

When passing through the catalyst bed, the reaction mixture stream is converted to a gaseous product stream containing mainly molecular nitrogen, water vapor, nitrous oxide (N ₂ O), nitrogen oxides NO _X , as well as the remaining unreacted molecular oxygen and ammonia. A portion (1 to 98 vol%, preferably up to 95 vol%, and more preferably 25 to 89 vol%) of the gaseous product stream is then separated at a temperature of 5 to 450 ° C, preferably at 70 to 330 ° C and more preferably at 90 ° C to 150 ° C, and returned to the reaction mixture stream.

Although the product gas stream can be condensed prior to recycling, the recycled portion is preferably recycled at a temperature above the water condensation temperature. This eliminates the need for additional equipment used to condense and evaporate the recycle stream before it is fed into the reactor. In this case, the product stream may condense after recycling a portion of it to the reactor. When the gaseous product stream is condensed prior to recycling a portion of it to the reactor, any conventional process can be used to evaporate the recycle stream, such as heat recovered from the product stream before condensation, a conventional heat exchanger or other heat transfer means. The recycle moiety may comprise N ₂ O, H ₂ O, NH ₃ , O ₂ , NO _X and N ₂ and the like.

The separated portion of the gaseous product stream can be continuously recycled to the reaction mixture in two steps. In a first step, the separated part of the gaseous product stream is mixed with continuously supplied air. In a second step, ammonia is added to the gas mixture obtained (although ammonia can be added in any step). Nitrogen may be added at any step and may also contain inert additives. The stream of gaseous reaction mixture may be prepared such that the molecular oxygen content of the reaction mixture remains between 1.0 and 20.0 vol%, preferably 1.5 to 15.0 vol%, and more preferably 2.0 to 12.5 vol%. %, while the ratio of volume concentrations of ammonia to molecular oxygen is in the range of 1.0 to 1.5.

Part of the gaseous product stream (5 to 90 vol%, preferably up to 80 vol% and more preferably 11 to 75 vol% of the total flow) is withdrawn to obtain the end product, namely nitrous oxide, which can be diluted with molecular nitrogen as inert gas. However, in order to improve the composition of the final product, part of the gaseous product stream passes through the catalyst bed for 9 * 9

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9999 99 99 * 9 9 * ♦ · · _ΝΟ Χ selective reduction with ammonia at 150 ° C to 500 ° C, preferably 175 ° C to 450 ° C and more preferably 200 ° C to 400 ° C. Reduction catalysts including V2O3 / Al2O3, V2O3 / TiO2 or Cr2O3 are used for this purpose. In addition to reaction (IV), the following reaction also produces nitrous oxide

4NO + 4NH ₃ = 4NO ₂ + 6H ₂ O (V)

Reactions (IV) and (V) reduce the content of nitrogen oxides (ΝΟχ), residual oxygen and ammonia in the end product.

If it is necessary to further reduce the residual oxygen content of the final product, combustible gases (CO, H ₂ , hydrocarbons) are introduced into the remaining parts of the product gas stream. These combustibles react with molecular oxygen only to form carbon dioxide (CO ₂ ) or water. The following reactions are in progress

CO + I / 2O2 = CO ₂ (VI)

H ₂ + I / 2O 2 = H ₂ O (VII)

C _x H _y + nO ₂ = x CO ₂ + y / 2H ₂ O (VIII)

To effect these reactions, the gaseous product stream passes at a temperature of from 50 ° C to 500 ° C, preferably at 175 ° C to 450 ° C, and more preferably at 200 ° C to 400 ° C, through a bed of strong oxidation catalyst based on metal oxides ( MnO2 / Al ₂ O _3, CuO / Cr ₂ O ₃ / Al ₂ O 3), or noble metals Pt / Al ₂ O _3, Pd / Al ₂ O _3). When leaving the catalyst, the N2O / O2 ratio is not less than 10, preferably not less than 20, and more preferably not less than 100.

Ammonia and water can be removed from the gaseous product stream in a known manner such as condensation and the like, and the final product is obtained as a dry gas containing nitrous oxide diluted with molecular nitrogen containing small amounts of impurities. If it is necessary to reduce the concentration of nitrous oxide in the final product to a certain value, an inert gas such as molecular nitrogen or carbon dioxide may be introduced into the gaseous reaction mixture or product gas stream.

Another embodiment of the invention relates to a process for producing nitrous oxide comprising a supply of a reaction mixture comprising ammonia and an oxidizing agent into the reactor, the oxidation of ammonia to form nitric oxide and NO _x, NO _x reduction to nitrous oxide to form a product stream of nitrous oxide.

The above oxidation step and the reduction step can be carried out in a single reactor or in separate reactors (which, as defined herein, comprises separate zones or chambers in a single reactor). In addition, the oxidation step and the reduction step can be carried out simultaneously or sequentially using one or more different catalysts. For example, the oxidation catalysts disclosed herein may be used, or a combination of oxidation catalysts in a single reactor and a reduction reactor

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4 catalysts (referred to herein) in another reactor (under the conditions set forth herein). Thus, when two (or more) reactors are used, the products from each reactor may be recycled to the feed of each reactor, or the reaction product from the last reactor may be recycled to the first reactor.

The oxidizing agent used may comprise oxygen, NO _x , air, ozone, HNO ₃ , or any oxidizing agent capable of oxidizing ammonia. The preferred oxidizing agent is oxygen.

The amount of NO _X present in the reaction product from the first reactor is greater than the amount of NO _X present in the reaction product from the last reactor. The amount of NO _x present in the reaction product from the last reactor is less than 5 vol%, preferably less than 3 vol%, and more preferably less than 1 vol% of the reaction product stream.

DETAILED DESCRIPTION OF THE INVENTION

The process of the invention is further defined with reference to the following illustrative examples

Example 1

The process for producing nitrous oxide is carried out as follows.

Dust-free air is added at a rate of 7.32 liters / minute to a separate portion of the product gas stream delivered at a rate of 21.0 liters / minute. Ammonia was added to the stirred stream at a rate of 1.24 g / minute. The thus obtained reaction mixture, the gaseous stream is continuously fed into a chemical reactor made of a metallic tube with an inner diameter of 15 mm with a fixed bed of manganese-bismuth catalyst (MnO2 / Bi ₂ O 3 / Al ₂ O 3) weighing 650 g inside the tube. The catalyst tubes are placed in a fluidized sand bed for intensive heat dissipation. The catalyst bed temperature is maintained at 300 ° C. The reaction mixture stream, which emerges from the catalyst bed, contains molecular nitrogen, water, nitrogen oxides (NO and NO2) and also nitrous oxide. At a temperature of 90 ° C ensuring that no condensation occurs, part of the gaseous product stream is separated and recycled to the catalyst bed. The remainder of the gaseous product stream is withdrawn from the recycling loop to obtain the final product using known methods.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 63.3, H ₂ O - 19.9, NO - 0.05, N ₂ O - 5 , 1, NH ₃ - 6.5, O ₂ - 4.9. The non-recycled portion of the gaseous product stream reaches 30% of the stream

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9999 99 99 99 99 of the gaseous product and having the following composition (vol.%): N ₂ - 63.8, H ₂ O - 27.3, NO - NO - 0.07, N ₂ O - 7.3, NH ₃ - 1.5, O ₂ -0.05.

Example 2

The process is carried out as in Example 1. A solid catalyst MnO ₂ / Bi ₂ O ₃ weighing 1200 g is used. The feed rate is 1.4 liters / minute, a separate portion of the gaseous product stream being supplied at 13.3 liters / minute. The ammonia feed rate is 0.22 g / minute. The catalyst bed temperature is maintained at 320 ° C. Product separation is performed at 320 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 64.7, H ₂ O - 24.7, NO - 0.15, N ₂ O - 6 , 47, NH ₃ - 2.0, O ₂ - 2.0. The non-recycled portion of the product gas stream is 88.7% and has the following composition (v / v): N ₂ - 64.8, H ₂ O - 27.5, NO - 0.17, N ₂ O - 7.29, NH ₃ - 0.1, O ₂ - 0.15.

Example 3

The process is carried out as in Example 1. A solid MnO ₂ catalyst with a weight of 1550 g is used. The air feed rate is 9.3 liters / minute, a separate portion of the product gas stream being delivered at a rate of 3.8 liters / minute. The ammonia feed rate was 1.46 g / minute. The catalyst bed temperature is maintained at 330 ° C. Product separation is performed at 330 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 64.3, H ₂ O - 8.7, NO - 0.04, N ₂ O - 1 , 68, NH ₃ - 12.8, O ₂ - 12.5. The non-recycled portion of the gaseous product stream is 75.0% and has the following composition (v / v): N ₂ - 65.1, H ₂ O - 27.4, NO - 0.17, N ₂ O - 6.66, NH ₃ - 0.25, O ₂ - 0.47.

Example 4

The process is carried out as in Example 1. A solid catalyst MnO ₂ / CuO weighing 850 g is used. The feed rate is 7.27 liters / minute, a separate portion of the product gas stream being supplied at a rate of 21.1 liters / minute. The ammonia feed rate is 1.30 g / minute. The catalyst bed temperature is maintained at 310 ° C. Product separation is carried out at 70 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 63.2, H ₂ O - 19.8, NO - 0.06, N ₂ O - 4 , 76, NH ₃ - 7.3, O ₂ - 4.9. The non-recycled portion of the gaseous product stream is 30.0% and has the following composition (by volume%): N ₂ - 63.5, H ₂ O - 27.2, NO - 0.08, N ₂ O - 6.79, NH ₃ - 2.32, O ₂ - 0.15.

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Example 5

The process is carried out as in Example 1. A solid catalyst MnO ₂ / Bi ₂ O ₃ / Fe ₂ O ₃ weighing 850 g is used. The air inlet rate is 6.32 liters / minute, the separated part of the gaseous product stream being supplied at 18.0 liters. /minute. The ammonia feed rate was 1.02 g / minute. Pure nitrogen was added to the gaseous reaction mixture at a rate of 4.31 liters / minute. The catalyst bed temperature is 310 ° C. Product separation is performed at 100 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 77.1, H ₂ O - 11.3, NO - 0.06, N ₂ O - 2 , 76, NH ₃ - 4.6, O ₂ - 4.3. The non-recycled portion of the gaseous product stream is 40.0% and has the following composition (v / v): N ₂ - 77.3, H ₂ O - 17.8, NO - 0.11, N ₂ O - 4.44, NH ₃ - 0.30, O ₂ - 0.08.

Example 6

The process is carried out as in Example 1. A gηθ2 / Βΐ2θ ₃ / Αΐ2θ ₃ catalyst with a mass of 650 g is used. The air inlet rate is 6.93 liters / minute, a separate portion of the gaseous product stream being delivered at 17.1 liters / minute. The ammonia feed rate was 1.08 g / minute. An inert gas containing 90 vol% nitrogen and 10 vol% CO 2 is added to the reaction mixture stream at a rate of 4.51 liter / minute. The catalyst bed temperature is 310 ° C. Product separation is performed at 100 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 73.4, H ₂ O - 10.9, NO - 0.06, N ₂ O - 2 , 70, NH ₃ - 4.8, O ₂ - 4.6, CO ₂ - 3.5. The non-recycled portion of the gaseous product stream is 43.0% and has the following composition (v / v): N ₂ - 73.5, H ₂ O - 17.1, NO - 0.11, N ₂ O - 4.74, NH ₃ - 0.16, O ₂ 0.09, CO ₂ -3.5.

Example 7

The process is carried out as in Example 1. The catalytic solid MnO 2 / Bi ₂ O ₃ / Al 2 O ₃ with a weight of 850 g. The feed rate of air is 4.35 l / minute, a separate part of the gaseous product stream is supplied rate 15.9 l / minute. The ammonia is supplied as an aqueous solution containing 20% by volume of ammonia by evaporation. The feed rate of this aqueous solution was 3.89 g / min. The catalyst bed temperature is 300 ° C. Product separation is performed at 100 ° C.

In the continuous mode at the indicated feed rates, the gaseous reaction mixture stream at the reactor inlet has the following composition (v / v): N ₂ - 36.6, H ₂ O - 52.0, NO - 0.06, N ₂ O - 2 , 68, NH ₃ - 5.1, O ₂ - 3.5. The non-recycled portion of the gaseous product stream is 37.0% and has the following composition (v / v): N ₂ - 36.7, H ₂ O - 57.2, NO - 0.09, N ₂ O - 4.25, NH ₃ - 1.58, O ₂ - 0.11.

··· 4 · · 4 4 ·

4 4 · 4 · 4 4 · 4 · ♦

4 4 4 4 4 4

Example 8

The process is carried out as in Example 2. The remainder of the gaseous product stream withdrawn to obtain the end product is passed through a V ₂ O ₅ / TiO ₂ catalyst bed to reduce nitrogen oxide to ammonia. The catalyst bed temperature is 320 ° C. The residual NO content of the catalyst bed is 0.005% by volume.

Example 9

The process is carried out as in Example 3. Hydrogen is added to the remainder of the product gas stream at a rate of 0.1 liter / minute and the mixture passes through a Pt / Al ₂ O 3 catalyst bed. The catalyst bed temperature is 330 ° C. The residual O ₂ content of the Pt catalyst bed is 0.025 vol%.

Example 10

The process for producing nitrous oxide is carried out as follows. The composition and flow rates of the reaction mixture continuously fed to the chemical reactor are the same as in Example 1. The process is carried out in a chemical reactor consisting of an adiabatic portion containing a fixed bed of Fe ₂ O3 based catalyst weighing 200 g and a cooled tubular portion. mm containing a fixed bed of MnO ₂ / Bi ₂ O ₃ / Fe ₂ O ₃ manganese-bismuth catalyst with a weight of 650 g). The temperature of the reaction mixture at the inlet to the adiabatic portion is 300 ° C and at the inlet to the tubular portion is about 280 ° C. The reaction mixture is cooled between the adiabatic portion and the tubular portion. The composition at the reactor outlet and recycled gas streams is identical to Example 1.

Example 11

The process for producing nitrous oxide is carried out as follows. Composition and flow rate of reaction mixture is continuously placed into a chemical reactor are the same as in Example 1. The chemical reactor is produced as a metal tube with an internal diameter of 20 mm with a fixed bed catalyst manganbismutového (MnO ₂ / Bi ₂ O 3 / Al ₂ O ₃₎ weighing 800 g inside the tube. The catalyst tube is placed in a fluidized sand bed for intensive heat dissipation and maintained at 280 ° C.

The temperature of the reaction mixture at the reactor inlet is 350 ° C. In all other respects, the process is carried out as in Example 1. The composition at the reactor outlet and recycled gas streams is identical to Example 1.

Claims (25)

PATENT CLAIMS A process for the production of an aliphatic dibasic acid, characterized in that the aromatic compound is hydroxylated in a reactor using nitrous oxide to form a phenolic compound which is reduced to form a cycloaliphatic ketonic and / or alcohol compound which is oxidized to form an aliphatic dibasic acid and a gaseous nitrous oxide gas stream which is processed into a stream of purified nitrous oxide gas, wherein the purified nitrous oxide gas stream is recycled back to the reactor. The method of claim 1, wherein the treatment comprises converting O ₂ to nitrous oxide and reducing NO _X to N ₂ and nitrous oxide. The process of claim 2, wherein the conversion of O ₂ comprises the conversion of O ₂ to nitrous oxide by oxidation of ammonia. The process according to claim 2, characterized in that NO _{X is} reduced by oxidation of ammonia, giving nitrous oxide as the reaction product. 5. The process of claim 1 wherein the stream of purified nitrous oxide is mixed with another nitrous oxide. The process according to claim 5, wherein the further nitrous oxide is produced by oxidation of ammonia. 7. The process of claim 6, wherein the oxidation of ammonia is carried out by supplying a reaction mixture containing ammonia, nitrous oxide and an oxidizing agent to the ammonia oxidation reactor, wherein the ammonia is oxidized to form a nitrous oxide product stream, separating at least a portion of the stream. nitrous oxide product to form a separate recycle stream which is fed to the ammonia oxidation reactor, wherein the nitrous oxide product stream is purified to form additional nitrous oxide. The method of claim 7, wherein the recycle stream comprises a portion of the nitrous oxide product stream, water, air, molecular oxygen, molecular nitrogen, nitrous oxide, NO _x or an inert gas. 9 9 ·· ·· · «·· ·· · ···· 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9999 99 99 99 99 999 The method of claim 7, wherein the recycle stream is separated from the nitrous oxide product stream at a temperature above the condensation temperature of water. The method of claim 7, wherein air, water, molecular oxygen, molecular nitrogen, nitrous oxide, ammonia or an inert gas are added to the recycle stream. 11. A process for producing nitrous oxide by reacting a gas stream containing NO _x, characterized by supplying to the reactor a reaction mixture consisting of ammonia and a gas stream comprising _NOx, whereby _NOx is reduced to produce a product stream of nitrous oxide. The method of claim 11, wherein at least a portion of the nitrous oxide product stream is separated to form a separate recycle stream that is fed to the reactor and that nitrous oxide is separated from the nitrous product stream. The process of claim 11, wherein the reaction mixture comprises a diluent comprising at least a portion of the nitrous oxide product stream, water, air, molecular oxygen, molecular nitrogen, nitrous oxide, ammonia, or an inert gas. 14. The process of claim 11 wherein air, water, molecular oxygen, molecular nitrogen, nitrous oxide, ammonia, or inert gas are added to the recycle stream. 15. A process for producing nitrous oxide by oxidizing ammonia, comprising introducing into the reactor a reaction mixture comprising ammonia and an oxidizing agent, oxidizing ammonia to produce a stream of nitrous oxide product as the primary component, and at least a portion of the stream of nitrous oxide product. separated at a temperature above the condensation temperature of the water to form a separate recycle stream which is fed to the reactor and the nitrous oxide is separated from the nitrous oxide product stream. The method of claim 15, wherein the reaction mixture comprises a diluent comprising a portion of the nitrous oxide product stream, water, air, molecular oxygen, molecular nitrogen, nitrous oxide or an inert gas. 00 0 · » ···· 00 · • • • • • 0 0 0 0 0 • • • 0 0 0 • • 0 * • 4 0 0 0 • · • » 0 0 0 « 0 0 17. The method of claim 15 wherein air, water, molecular oxygen, molecular nitrogen, nitrous oxide, ammonia, or an inert gas are added to the recycle stream. The method of claim 15, wherein the oxidizing agent comprises oxygen, NO _X , oxygen, ozone or HNO ₃ . 19. A process for producing nitrous oxide, characterized in that the reaction mixture comprising ammonia and an oxidizing agent introduced into the reactor where oxidation occurs ammonia to form dinitrogen monoxide and _NOx, which is reduced to nitrous oxide to form a product stream of nitrous oxide. 20. The process of claim 19 wherein part of the nitrous oxide product stream is recycled to the reactor. 21. The process of claim 19 wherein the oxidation is carried out in a first reactor to form a first nitrous oxide product stream, and the reduction is carried out in a second reactor to form a second nitrous oxide product stream. 22. The process of claim 21 wherein the first and second reactors are charged with different catalysts. 23. The process of claim 21 wherein a portion of the second nitrous oxide product stream is recycled to the first or second reactor. 24. The method of claim 21 wherein the amount of nitrous oxide present in the second product stream is greater than the amount of nitrous oxide present in the first product stream. The method of claim 19, wherein the oxidizing agent comprises oxygen, NO _x , oxygen, ozone or HNO ₃ .