KR102080950B1 - Process for the continuous preparation of hydroxyamine - Google Patents

Abstract

A process for producing hydroxylammonium in a reaction zone in a continuous process, optionally comprising direct introduction of nitric acid containing less than 0.1 ppm to the reaction zone, comprising: a vessel comprising the introduced nitric acid in steel and Transport, store and deliver to pipes; Conducting the reaction in a vessel wherein the walls of the vessel and the connecting pipe comprise steel; Wherein the steel comprises 0 to 0.08 wt% C and 0 to 0.03 wt% Mo.

Description

Continuous production method of hydroxylamine {PROCESS FOR THE CONTINUOUS PREPARATION OF HYDROXYAMINE}

The present invention relates to a process for preparing hydroxylammonium in a reaction zone in a continuous process, comprising the steps of: i) introducing nitric acid, optionally comprising less than 0.1 ppm Mo, directly into the reaction zone, ii) The wall of the vessel carries, stores and delivers nitric acid to a vessel consisting essentially of Mo-free and preferably carbon-free steel, and iii) the reaction zone is Mo-free and preferably Is carried out in a vessel consisting essentially of carbon-free steel.

An important use of the hydroxylammonium salts is in the preparation of oximes from ketones or aldehydes, in particular in the preparation of cyclohexanone oximes from cyclohexanone. For this oxime preparation method, a circulation process is known in which the aqueous acid-buffered reaction medium continues to circulate through the hydroxylammonium salt synthesis zone and the oxime synthesis zone. The reaction medium is acid-buffered, for example, by phosphoric acid and / or sulfuric acid and buffer salts derived from these acids, such as alkali and / or ammonium salts. In the hydroxylammonium salt synthesis zone, hydrogen is used to convert nitrate ions or nitrogen oxides to hydroxylamine. The hydroxylamine is reacted with the free buffered acid to produce the corresponding hydroxylammonium salt, which is then passed to the oxime synthesis zone where it is reacted with the ketone to produce the corresponding oxime while releasing the acid. After the oxime is separated from the reaction medium, the reaction medium is recycled to the hydroxylammonium salt synthesis zone and fresh nitrate ions or nitrogen oxides are added to the reaction medium.

When the hydroxylammonium salt synthesis starts from a solution of phosphoric acid and nitrates, the above-mentioned chemical reactions appear as follows:

Reaction 1) Preparation of hydroxylammonium in the hydroxylammonium salt synthesis zone:

_{2 H 3 PO 4 + NO 3} - + 3 H 2 -> NH 3 OH + + 2 H 2 PO 4 - + 2 H 2 O

Reaction 2) Preparation of oxime in oxime synthesis zone:

Reaction 3) After removing the formed oxime, HNO ₃ is fed to compensate for the consumption of nitrate ion source:

H ₃ PO _{4 ^{+ H 2 PO 4 - + HNO}} 3 + 3 H 2 O -> 2 H 3 PO 4 + NO 3 - + 3 H 2 O

The first reaction is heterogeneously catalyzed. Preferably, the catalyst is present as finely divided solids as a dispersed phase in the liquid reaction mixture.

The resulting mixture of the first reaction is an aqueous inorganic process liquid comprising a suspension of solid catalyst particles in a hydroxylammonium salt solution.

Before the aqueous inorganic process liquid is transferred to the oxime synthesis zone (reaction 2), the solid catalyst particles are preferably separated from the aqueous inorganic process liquid. After filtration, the inorganic process liquid is a hydroxylammonium salt solution filtrate.

CN101058410, CN1547552, CN101218171 and CN1418809 describe a number of general methods for preparing hydroxylammonium salts.

Another process (eg, the process described in US5364609) uses an additional step in which ammonia is combusted to form NO, NO ₂ and water, which are introduced into the reactor to form nitric acid together. Nitric acid is then reacted with hydrogen to form hydroxylammonium. During the formation of hydroxylammonium, N ₂ O and N ₂ are formed as gaseous by-products, and further ammonia is formed and dissolved in the aqueous inorganic process solution. Ammonia then reacts with NO and NO ₂ from the combustion process and forms N ₂ gas (Piria reaction).

It is also possible in this process to add nitric acid directly (instead of being formed in the same reaction system), but this can lead to a harmful accumulation of ammonia since there is no dissolved NO and NO ₂ to react. Thus, there is a limitation on how much nitric acid can be added directly in a short time without the presence of NO and NO ₂ .

The limit is the production concentration of ammonia that needs to be low to avoid crystallization .

However, in order to increase the production of hydroxylammonium and give time to stop the ammonia combustion unit for repair, for example, it is desirable to be able to add nitric acid directly. The problem with adding nitric acid directly is that it is a liquid and not a gas and tends to dissolve the steel vessels that transport and use it. Most of the rivers contain some molybdenum. It is known that molybdenum is detrimental to the selectivity of the hydroxylammonium reaction, for example 1 ppm of Mo in the reaction medium can cause a more than 2% reduction in hydroxylammonium selectivity.

Selectivity is defined as the molar ratio of hydroxylammonium production to proton (H ⁺ ) consumption where one hydroxylammonium requires two protons (H ⁺ ). As used herein, to obtain 100% conversion, the "hydroxyl aluminum selectivity" (selectivity for the production of hydroxylammonium) is defined as the amount of hydroxylammonium produced in the reaction zone divided by the amount of H ⁺ consumed in the reaction zone. It is defined as the molar ratio of twice the amount. Low selectivity means that more undesirable byproducts are produced.

US4340575 discloses a hydroxylammonium salt prepared by a process comprising the catalytic reduction of nitrogen monoxide with hydrogen in a dilute aqueous inorganic acid at elevated temperature in the presence of a suspended platinum catalyst, wherein the reaction is a wall-conventional Phosphorus copper-free molybdenum-containing austenitic chromium-nickel steel (16 to 28 wt% (wt%) of chromium, 20 to 50 wt% nickel, 1 to 4 wt% molybdenum and up to 0.1 wt% carbon) And titanium in an amount of at least 5 times and at most 1.0 weight percent of carbon, or niobium or tantalum in an amount of at least 8 times and at most 1.5 weight percent of carbon. do.

EP1901994 discloses a process and equipment in which it is also possible to continuously produce hydroxylammonium by reducing nitrate ions or nitrogen oxides to hydrogen in the presence of a catalyst, wherein it is also possible to provide nitric acid directly instead of producing nitric acid. EP1451100 also discloses that the hydroxylammonium synthesis zone can concentrate nitrate ions by forming nitric acid in situ by adding nitric acid or absorbing a nitrogen containing gas into the aqueous medium.

It is also known in the art to treat and remove Mo from the reaction zone.

US4062927 describes a method for removing dissolved molybdenum from a nitrate / nitrogen monoxide solution by co-precipitation with complex iron-ammonium phosphate.

US7399885 describes a method for removing dissolved molybdenum from an acid buffer solution (after pretreatment) by selective absorption onto a specific resin / polymer.

US3767758 describes that Mo lowers the selectivity for hydroxylamine, leading to the production of more ammonia.

It is therefore an object of the present invention to provide a process that exhibits improved selectivity while still allowing direct addition of nitric acid as needed.

Thus, according to the present invention, there is provided a process for producing hydroxylammonium in a reaction zone in a continuous process, the process comprising

I) combusting ammonia to form NO, NO ₂ and water;

II) a NO, NO _2, and by introducing the water as NO, NO ₂ absorption zone to form nitric acid and nitric acid from step I) in a reaction zone by reduction with hydrogen, thereby forming a hydroxyl ammonium; And / or

III) introducing nitric acid containing less than 0.1 ppm Mo directly into the reaction zone and reducing nitric acid to hydrogen to form aqueous hydroxylammonium

Including,

Wherein the nitric acid is transported, stored and delivered in vessels and pipes comprising steel;

Conducting the reaction in a vessel wherein the walls of the vessel and the connecting pipe comprise steel;

The steel comprises 0 to 0.08 wt% C and 0 to 0.03 wt% Mo.

Preferably the steel consists essentially of a steel selected from the group consisting of:

0-0.08 wt% C, 0-2.0 wt% Mn, 0-2.0 wt% Si, 0-0.045 wt% P, 0-0.03 wt% S, 17-21 wt% Cr, 0-0.03 wt% Mo, 8.0 Quench annealed steel A, including from 13 wt% Ni;

0-0.03 wt% C, 0-2.0 wt% Mn, 0-1.0 wt% Si, 0-0.045 wt% P, 0-0.03 wt% S, 17-21 wt% Cr, 0-0.03 wt% Mo, 8.0 Low carbon steel B, including 1 to 13.0 wt% Ni;

0 to 0.08 wt% C, 0 to 2.0 wt% Mn, 0 to 2.0 wt% Si, 0 to 0.045 wt% P, 0 to 0.04 wt% S, 17 to 21 wt% Cr, 0 to 0.03 wt% Mo, 9.0 Stabilized steel C comprising from 13.0 wt% Ni, and Ti (minimum, 5 times to 0.8 wt% of carbon) or Nb + Ta (minimum, 8 times to 1.1 wt% of carbon).

Preferably the resulting aqueous hydroxylammonium comprises less than 3 ppm Mo, more preferably less than 2.5 ppm Mo, most preferably less than 2.0 ppm Mo and in particular less than 1.5 ppm ppm. 3 ppm Mo in aqueous hydroxylammonium corresponds to 0.0003 wt%.

NO, NO ₂ The absorption zone is in a different vessel than the vessel in which the reaction zone is located, but may be in the same vessel.

During normal preparation, the ratio of nitric acid produced in step II) to nitric acid added in step III) is preferably in the range of 100: 0 to 10:90.

If the ammonia combustion device is stopped during production, for example for maintenance of the ammonia combustion device, the ratio of nitric acid produced in step II) to nitric acid added in step III) is 0: 100.

Preferably, the ammonia combustion device is stopped for 100 hours or less.

Step III (without step II) is preferably carried out continuously up to 100 hours. If step III (without step II) is carried out continuously for more than 100 hours, the ammonia concentration may be too high, the salt in the inorganic process liquid may crystallize, and the resulting precipitate may block pipes, valves, filters, heat exchangers, etc. Can be.

Preferably step III (without step II) is carried out continuously for up to 80 hours, most preferably for up to 60 hours. Preferably, the time period between continuously performing step III (without step II) and subsequent step III) without step II) is at least 100 hours.

The ratio of nitric acid produced in step II) to nitric acid added in step III) during 100 hours of normal operation is from 100: 0 to 20:80.

Various steels for the production of vessels, pipes and reactors for the production of hydroxylammonium are well known. This includes steels known as 304, 316, 304L or 316L. Different grades have different levels of molybdenum and other metals. In addition, the level of carbon and other elements can also affect the corrosion resistance.

The carbon range is up to 0.08 wt% for grades 304 and 316, and up to 0.030 wt% for grades 304L and 316L.

All other elements are in essentially the same range (for example, the range for nickel is 8.00 to 10.50 wt% and the range for 304L is 8.00 to 12.00 wt%).

To overcome the risk of inter-crystal corrosion (weld decay), which was recognized as a problem in the early days of applying these steels, low-carbon 'variants' (as a substitute for the 'standard' (316) carbon range grade) ( 316L) has been established. The corrosion may occur when the steel is maintained for several minutes depending on the temperature in the temperature range of 450 to 850 ° C. and then exposed to aggressive corrosion environments. The corrosion then occurs near grain boundaries.

Preferably the carbon level of the steel is 0 to 0.03 wt% C. If the carbon level is less than 0.030 wt%, this intercrystallization corrosion does not occur after this temperature exposure, especially during the short periods of time normally encountered in areas where the welds are heat affected in the 'thick' part of the steel. Low carbon types can also be welded more easily than standard carbon types.

The steel can also be annealed. Annealing is a heat treatment in which a material changes to change its properties such as strength and hardness. This is a process that creates a state by heating above the recrystallization temperature, maintaining a suitable temperature and then cooling. In the case of steel, this process is carried out by heating the material considerably for a while (generally until glowing) and cooling. Annealing does not reduce the carbon content, but makes the distribution of the elements more homogeneous, thus improving the corrosion resistance.

More preferably austenitic steels are used in the present invention. Austenitic, also known as gamma phase iron, is a metallic non-magnetic allotrope with solid alloying elements or a solid solution of iron. In ordinary carbon steels, austenite is present at temperatures above the critical or eutectic temperature of 1,000 K (1340 Pa) and the other alloys of the steel have different eutectic temperatures.

The catalysts applied in the preparation of the hydroxylammonium salts consist mostly of platinum group metals, for example Pd or (Pd + Pt), as active ingredients on carrier materials such as carbon. The catalyst can be activated by the presence of one or more catalyst activators. The catalyst activator may be an element selected from the group comprising Cu, Ag, Cd, Hg, Ga, In, Ti, Ge, Sn, Pb, As, Sb and Bi. Most preferably the catalyst activator is Ge. Compounds containing the elements in question may be used as catalyst activators, for example oxides, nitrates, phosphates, sulfates, halides, and acetates. The elements or compounds thereof can be applied directly to the catalyst as described in US3767758 or added to the reaction medium.

The catalyst used in the preparation of the hydroxylammonium salt solution (reaction 1) preferably comprises a noble metal on a support, preferably platinum (Pt), palladium (Pd), or a combination of palladium and platinum on a support.

Pure Pd is generally preferred, but the Pd: Pt weight ratio can vary. Pure Pd may contain some Pt impurities. Preferably Pd comprises less than 25 wt%, more preferably less than 5 wt%, even more preferably less than 2 wt% and especially less than 1 wt% Pt.

Preferably, the support comprises carbon (eg graphite, carbon black, or activated carbon) or alumina support, most preferably graphite or activated carbon. The catalyst used in the hydroxylammonium salt synthesis zone preferably comprises 1 to 25 wt%, more preferably 5 to 15 wt% of the precious metal relative to the total weight of the support and the catalyst.

Generally, the catalyst is present in the hydroxylammonium salt synthesis zone in an amount of 0.05 to 25 wt%, preferably 0.2 to 15 wt%, more preferably 0.5 to 5 wt% relative to the total weight of the inorganic process liquid. do.

The catalyst particles generally have an average size of 1 to 150 μm, more preferably 5 to 100 μm, more preferably 5 to 60 μm and most preferably 5 to 40 μm. "Average particle size" means that 50% by volume of the particles are larger than the specified diameter.

Preferably, the catalyst activator is 0.01 to 100 mg / g catalyst, preferably 0.05 to 50 mg / g catalyst, more preferably 0.1 to 10 mg / g catalyst, most preferably 1 to 7 mg / g Present in an amount of catalyst.

The production apparatus for producing hydroxylammonium may be any suitable reactor, such as a machine having a mechanical stirrer or column, most preferably a bubble column. Examples of suitable bubble columns are described in NL6908934.

A typical reactor form for preparing an aqueous hydroxylammonium salt solution and for separating solid catalyst particles is a hydrogenated bubble column reactor with cooling compartments. The reactor form usually includes a plurality of sets of gas separation vessels and filtration vessels.

The inorganic process liquid from the bubble column reactor is transferred through a gas separation vessel to a filtration vessel containing a filter for the first filtration step.

Subsequently, some (usually about 3-10%) hydroxylammonium salt solution filtrate is transferred from the filtration vessel to the filtrate vessel, from there into the filtrate buffer vessel, and from there into the oxime synthesis zone. The remaining (usually about 97-90%) hydroxylammonium salt solution filtrate is transferred back to the hydrogenation column and cooled in the cooling zone. The pipe between the filtration vessel and the cooling zone may also comprise cooling means.

The invention will be further illustrated by the following examples, which are not intended to be limiting.

Example  One

In a hydroxylamine phosphate oxime plant process according to DSM HPO ^® technology, operating in a continuous manner, an inorganic process liquid comprising a hydroxylammonium salt solution was prepared. The average particle size of the catalyst particles (10 wt% palladium / activated carbon) was approximately 15 μm.

NO, NO ₂ and water were produced in the ammonia combustion plant, which were then introduced into the absorption zone to form nitric acid, which was then transferred to the reaction zone, followed by reduction of nitric acid with hydrogen to form hydroxylammonium.

After 200 hours, food grade nitric acid (60-65% concentration) was introduced directly into the reaction zone and reduced with hydrogen to form aqueous hydroxylammonium.

The food grade nitric acid was transported, stored and delivered to vessels and pipes, the reaction comprising a steel consisting essentially of low carbon steel B (including 0 to 0.03 wt% C and 0 to 0.03 wt% Mo) of the walls of the vessel and pipe. Was carried out in a vessel.

Mo in food grade nitric acid and resulting hydroxylammonium using atomic absorption spectroscopy using a Thermo Scientific iCAP6500 (ICP-AES) spectrometer or a Perkin Elmer DRC-e (ICP-MS) spectrometer Measurement of the concentration was performed.

The nitric acid or hydroxylammonium ammonium solution can be diluted with water to prevent crystallization at lower temperatures in the spectrometer.

The Mo content of the feedstock solutions such as food grade nitric acid (HNO ₃ ) and H ₃ PO ₄ was measured, which was found to be less than 0.1 ppm. The Mo content of the resulting aqueous inorganic process liquid containing hydroxylammonium was measured and found to be less than 1 ppm.

compare Example  2:

In Comparative Example 2, Example 1 was repeated except that the vessel and the wall of the pipe were made of a vessel comprising a steel consisting essentially of 316 steel with more than 0.03 wt% Mo.

The Mo content of the resulting aqueous inorganic process liquid comprising hydroxylammonium was measured, which was found to increase to 3-4 ppm Mo, and lower hydroxylammonium selectivity was observed.

Claims (11)

A process for preparing hydroxylammonium in the reaction zone in a continuous process,
The above method
I) combusting ammonia to form NO, NO ₂ and water;
II) step by introducing a NO, NO ₂ and water from I) as NO, NO ₂ absorption zone was reduced by hydrogen to form an acid, and the nitric acid in the reaction zone, to form a hydroxyl ammonium; And
III) introducing nitric acid containing less than 0.1 ppm Mo directly into the reaction zone and reducing the nitric acid with hydrogen to form aqueous hydroxylammonium
Or
The above method
III) introducing nitric acid containing less than 0.1 ppm Mo directly into the reaction zone and reducing the nitric acid with hydrogen to form aqueous hydroxylammonium
Including,
At this time,
Conveying, storing and delivering nitric acid introduced in step III) to vessels and pipes comprising steel;
In steps II) and III) a reaction of reducing nitric acid with hydrogen to form hydroxylammonium is carried out in a vessel wherein the walls of the vessel and the connecting pipe comprise steel;
Wherein the steel comprises 0 to 0.08 wt% C and 0 to 0.03 wt% Mo. The method of claim 1,
Wherein the steel comprises 0 to 0.03 wt% C. The method of claim 1,
Wherein said steel consists of a steel selected from the group consisting of:
0-0.08 wt% C, 0-2.0 wt% Mn, 0-2.0 wt% Si, 0-0.045 wt% P, 0-0.03 wt% S, 17-21 wt% Cr, 0-0.03 wt% Mo, 8.0 Quench annealed steel A, including from 13 wt% Ni;
0-0.03 wt% C, 0-2.0 wt% Mn, 0-1.0 wt% Si, 0-0.045 wt% P, 0-0.03 wt% S, 17-21 wt% Cr, 0-0.03 wt% Mo, 8.0 Low carbon steel B, including 1 to 13.0 wt% Ni;
0 to 0.08 wt% C, 0 to 2.0 wt% Mn, 0 to 2.0 wt% Si, 0 to 0.045 wt% P, 0 to 0.04 wt% S, 17 to 21 wt% Cr, 0 to 0.03 wt% Mo, 9.0 Stabilized steel C comprising from 13.0 wt% Ni, and Ti (minimum, 5 times to 0.8 wt% of carbon) or Nb + Ta (minimum, 8 times to 1.1 wt% of carbon). The method of claim 1,
The resulting aqueous inorganic process liquid comprising hydroxylammonium comprises less than 3 ppm Mo. The method of claim 1,
The nitric acid added in step III) comprises less than 0.05 ppm Mo. The method of claim 1,
During normal operation, the ratio of nitric acid produced in step II) to nitric acid added in step III) is in the range of 100: 0 to 10:90. The method of claim 1,
Wherein step III) is carried out continuously for no more than 100 hours without step II). The method of claim 1,
Wherein the time period between performing step III) continuously without step II) and performing step III) without step II) the next time is at least 2 days. The method of claim 1,
For more than 100 hours of normal operation,
a) the ratio of nitric acid produced in step II) to nitric acid added in step III) is from 100: 0 to 20:80;
b) the time to perform step III) continuously without step II) Method, which is up to 100 hours. The method of claim 1,
The steel is 0 to 0.03 wt% C, 0 to 2.0 wt% Mn, 0 to 1.0 wt% Si, 0 to 0.045 wt% P, 0 to 0.03 wt% S, 17 to 21 wt% Cr, 0 to 0.03 wt And a low carbon steel B comprising% Mo and 8.0 to 13.0 wt% Ni. The method of claim 1,
Wherein the steel is an austenite steel.