TW201332885A - Process for the continuous preparation of hydroxylamine - Google Patents

Abstract

A method for preparing hydroxylammonium in a reaction zone in a continuous process, comprising optionally directly introducing nitric acid comprising < 0.1 ppm Mo into the reaction zone; wherein the nitric acid introduced is transported, stored, transferred in vessels and pipes comprising steel; wherein the reaction is carried out in vessels of which the walls of the vessels and connecting pipes comprise steel; wherein said steel comprises 0 to 0.08 wt% C and 0 to 0.03 wt% Mo.

Description

Method for continuously producing hydroxylamine

The present invention relates to a process for the preparation of hydroxylamine in a continuous process in a reaction zone comprising i) optionally adding nitric acid containing <0.1 ppm molybdenum to the reaction zone; and ii) wherein the nitric acid is substantially In-container transport, storage and transfer of steel comprising no molybdenum and preferably carbon-free steel; and iii) the reaction zone is substantially free of molybdenum-free and preferably carbon-free steel at the wall It is carried out in a container consisting of steel.

An important use of hydroxylamine salts is in the preparation of hydrazines from ketones or aldehydes, in particular cyclohexanone oxime from cyclohexanone. For the preparation of the hydrazine, in the known recycling process, the aqueous acidic buffered reaction medium is kept in circulation in the hydroxylamine salt synthesis zone and the hydrazine synthesis zone. The reaction medium is buffered with a buffer salt such as phosphoric acid and/or sulfuric acid and these acids, such as a basic salt and/or ammonium hydrochloride. In the hydroxylamine salt synthesis zone, the nitrate ion or nitrogen oxide is converted to hydroxylamine with hydrogen. The hydroxylamine reacts with the free buffer acid to form the corresponding hydroxylamine salt, which is then fed to the hydrazine synthesis zone where it reacts with the ketone to form the corresponding oxime while releasing the acid. After the rhodium is separated from the reaction medium, the reaction medium is recycled to the hydroxylamine salt synthesis zone and new nitrate ions or nitrogen oxides are added to the reaction medium.

In the case of synthesizing a hydroxylamine salt with a phosphoric acid and a nitrate solution, the chemical reaction is expressed as follows: Reaction 1) Preparation of hydroxylamine in a hydroxylamine 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 hydrazine in the hydrazine synthesis zone:

Reaction 3) After separating the formed hydrazine, add new nitrate ions in the form of HNO ₃ : 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 a dispersed phase in the liquid reaction mixture in the form of a uniformly dispersed solid.

The reaction product mixture of the first step is an aqueous inorganic process liquid containing a suspension of solid catalyst particles in a hydroxylamine salt solution.

The solid catalyst particles are preferably separated from the aqueous inorganic process liquid before the aqueous inorganic process liquid is fed to the helium synthesis zone (Reaction 2). After filtration, the inorganic process liquid is a hydroxylamine salt solution filtrate.

Background of the invention

CN101058410, CN1547552, CN101218171 and CN1418809 describe a number of general methods for the preparation of hydroxylamine salts.

Another method (as described in US Pat. No. 5,364,609) utilizes an additional step in which ammonia is combusted to form NO, NO ₂ and water, and NO, NO ₂ and water are introduced into the reactor and co-reacted to form nitric acid, followed by nitric acid and Hydrogen reacts to form hydroxylamine. During the formation of hydroxylamine, the N ₂ O and N ₂ produced are gaseous by-products, and additionally ammonia is formed which is soluble in the aqueous inorganic process liquid. The ammonia is sequentially reacted with NO and NO ₂ produced during the combustion to form nitrogen (Piria reaction).

In the above process, it is also possible to directly add nitric acid (instead of in situ preparation), but this is not conducive to the production of ammonia because no dissolved NO and NO ₂ participate in the reaction. Therefore, there is a limit to how much nitric acid can be directly added in the absence of NO and NO ₂ for a certain period of time. This limitation is the final concentration of ammonia water, which is relatively low in order to avoid crystallization.

However, it is desirable to be able to directly add nitric acid to increase the production of hydroxylamine and to provide a time stop for the ammonia combustion equipment to ensure maintenance. The problem with direct addition of nitric acid is that nitric acid is a steel container that is not a gas and tends to dissolve and transport nitric acid. Most steels contain a certain amount of molybdenum. It is well known that molybdenum impairs the selectivity of the hydroxylamine reaction. For example, 1 ppm of molybdenum in the reaction medium causes a decrease in hydroxylamine selectivity of more than 2%.

The selectivity is defined as the molar ratio of hydroxylamine production to proton (H ⁺ ) consumption, where one hydroxylamine requires two protons (H ⁺ ). To obtain 100% conversion, the 'hydroxylamine selectivity' (selectivity to the hydroxylamine product) used herein is defined as the molar ratio of the amount of hydroxylamine produced in the reaction zone to the amount of H ⁺ consumed in the reaction zone. Low selectivity means more undesirable by-products.

No. 4,340,575 describes a process for the production of hydroxylamine salts which comprises a process for the catalytic reduction of nitrous oxide with hydrogen in the presence of a suspended platinum catalyst in a high temperature environment in a dilute aqueous mineral acid, wherein the reaction is carried out in a vessel, the wall It is composed of a traditional chromium-nickel steel containing no copper-containing austenite, which The steel contains 16-28% by weight of chromium, 20-50% by weight of nickel, 1-4% by weight of molybdenum and up to 0.1% by weight of carbon, and further contains a certain amount of titanium, and the content of titanium is at least 5 The carbon content is not more than 1.0% by weight, or contains a certain amount of cerium, and the content of cerium is at least 8 times the carbon content but not more than 1.5% by weight.

EP 1901994 discloses a process and apparatus for the continuous production of hydroxylamine by reduction of nitrate ions or nitrogen oxides with hydrogen in the presence of a catalyst, in which it is also possible to provide nitric acid directly rather than to produce nitric acid. EP 1 451 100 also discloses a solution for providing nitrate ions to a hydroxylamine synthesis zone by the addition of nitric acid or by in situ preparation of nitric acid in a water-containing medium.

The prior art also provides techniques for adding molybdenum to the reaction zone and removing it from the reaction zone.

No. 4,062,927 describes a process for the removal of dissolved molybdenum from a nitrate/nitric oxide solution by co-precipitation using an iron-ammonium phosphate complex.

US7399885 describes a process for removing dissolved molybdenum from an acidic buffer solution (after pretreatment) using selective adsorption of a resin/polymer.

No. 3,767,758 describes that molybdenum reduces the selectivity to hydroxylamine and results in more ammonia production.

Summary of invention

Accordingly, it is an object of the present invention to provide a process for the preparation of hydroxylamine which can exhibit both improved selectivity and the direct addition of nitric acid as required.

Thus, in accordance with the present invention, there is provided a process for the preparation of hydroxylamine in a continuous process in a reaction zone, the process comprising the steps of: I) burning ammonia to produce NO, NO ₂ and water; II) the NO of step I), NO ₂ and water are introduced into the NO, the NO ₂ absorption zone generates nitric acid, and the nitric acid is reduced by hydrogen in the reaction zone, thereby producing hydroxylamine; and/or III) directly introducing nitric acid containing <0.1 ppm molybdenum into the reaction zone and reducing the nitric acid with hydrogen Thereby producing aqueous hydroxylammonium; wherein the nitric acid is transported, stored and transferred in a steel-containing vessel and pipe; wherein the reaction is carried out in a vessel in which the wall and the connecting pipe comprise steel; wherein the steel contains 0-0.08 wt % carbon and 0-0.03 wt% molybdenum.

Preferably the steel consists essentially of steel selected from the group consisting of: quench-annealed steel A comprising 0-0.08 wt% carbon, 0-2.0 wt% manganese, 0-2.0 wt% bismuth, 0-0.045 wt% Phosphorus, 0-0.03 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% molybdenum, 8.0-13 wt% nickel; low carbon steel B contains 0-0.03 wt% carbon, 0-2.0 wt% manganese, 0-1.0 Wt% 矽, 0-0.045 wt% phosphorus, 0-0.03 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% molybdenum, 8.0-13.0 wt% nickel; stable steel C contains 0-0.08 wt% carbon, 0 - 2.0 wt% manganese, 0-2.0 wt% bismuth, 0-0.045 wt% phosphorus, 0-0.04 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% molybdenum, 9.0-13.0 wt% nickel and or titanium ( Minimum: 5 times wt% carbon - max: 0.8 wt% carbon) or 铌 + 钽 (minimum: 8 times wt% carbon - max: 1.1 wt% carbon).

Preferably, the resulting aqueous hydroxylamine contains <3 ppm molybdenum, more preferably less than <2.5 ppm molybdenum, most preferably <2.0 ppm molybdenum, especially <1.5 ppm molybdenum. Watery 3 ppm of molybdenum in hydroxylamine is equivalent to 0.0003 wt%.

The NO, NO ₂ absorption zone and reaction zone are in separate vessels, but may be in the same vessel.

In conventional production, preferably, the ratio of the nitric acid produced in step II) to the nitric acid added in step III) ranges from 100:0 to 10:90.

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

Preferably, the ammonia combustion apparatus is stopped for no more than 100 hours.

Preferably, step III (without step II) is carried out continuously for no more than 100 hours. If step III (without step II) is carried out continuously for more than 100 hours, the ammonia concentration becomes too high, and the risk of salt crystallization in the inorganic process liquid occurs and the resulting precipitate can clog the pipes, valves, filter heat exchange equipment, and the like.

Preferably, step III (without step II) is carried out continuously for no more than 80 hours, most preferably continuously for no more than 60 hours.

Preferably, there is a period of at least 100 hours between the continuous execution of step III (without step II) and the next continuous step III (without step II).

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

It is well known that a range of steels can be used to produce vessels, pipes and reactors for the preparation of hydroxylamine. This includes steel 304, 316, 304L or 316L. The grades of steel are different, and the content of molybdenum and other metals is also different. In addition, the content of carbon and other elements can also affect the corrosion resistance of the reactor.

Steels 304 and 316 have a carbon content range of up to 0.08 wt%, and steels 304L and 316L have a carbon content range of up to 0.030 wt%.

All other elements have a substantially identical range (for example, for steel 304, nickel ranges from 8.00 to 10.50 wt%, and for steel 304L, nickel ranges from 8.00 to 12.00 wt%).

To overcome the risk of intergranular corrosion at the beginning of the application (weld decay), a lower carbon content &apos;variant&apos; (316L) was developed to replace steel (316) with a "standard" carbon content. The conclusion is whether the steel can withstand temperatures of 450-850 ° C for a few minutes, depending on the temperature and the highly corrosive environment that is subsequently exposed. Corrosion then occurs at the grain boundaries.

Preferably the steel has a carbon content of from 0 to 0.03 wt% carbon. If the carbon content is less than 0.030 wt%, exposure to the above temperatures, especially in the 'thickness' section of the steel, will normally expose the heat affected zone of the solder joint for a period of time, then intergranular corrosion will not occur. Low carbon types are also easier to weld than standard carbon types.

Steel can also be annealed. Annealing is a heat treatment that causes changes in the properties of the material, such as strength and hardness. The annealing condition is produced by heating above the recrystallization temperature described above, maintaining a suitable temperature, and then cooling. For steel, this process is to fully heat the material for a period of time (generally heated to red) and then cool. Annealing does not reduce the carbon content but results in a more uniform distribution of elements, which increases corrosion resistance.

More preferably, the present invention uses austenitic steel.

Austenite, also known as gamma phase iron, is a homomorphic body of a non-magnetic metal iron or iron solid solution and contains alloying elements. In ordinary carbon steel, Austria The celite exists in the above-mentioned critical eutectoid temperature of 1,000 K (1,340 °F); other alloy steels have different eutectoid temperatures.

The catalyst used in the preparation of the hydroxylamine salt consists essentially of a metal selected from the group consisting of platinum, such as a catalyst having palladium or (palladium + platinum) as an active ingredient on, for example, a carbon support. The catalyst can be activated by the presence of one or more catalyst activators. The catalyst activator may be selected from the group consisting of copper, silver, cadmium, mercury, gallium, indium, antimony, bismuth, tin, lead, arsenic, antimony and bismuth. Most preferably, the catalyst activator is hydrazine. Compounds containing the elements, such as oxides, nitrates, phosphates, sulfates, halides and acetates, can also be used as catalyst activators. The elements as described in US Pat. No. 3,767,758 or their compounds may be incorporated directly into the reaction medium or added to the reaction medium.

The catalyst used in the preparation of the hydroxylamine salt solution (Reaction 1) preferably contains a platinum (Pt), palladium (Pd) or platinum and palladium composition on a support heavy metal, preferably on a support.

Although pure palladium is generally preferred, pure palladium may contain certain platinum impurities, and the weight ratio of palladium:platinum in pure palladium may vary. Preferably, the palladium contains less than 25% by weight of platinum, more preferably less than 5% by weight, further preferably less than 2% by weight, particularly preferably less than 1% by weight of platinum.

Preferably, the support comprises carbon (e.g., graphite, carbon black, or activated carbon) or an alumina support, more preferably graphite or activated carbon. The catalyst used in the hydroxylamine salt synthesis zone preferably contains from 1 to 25% by weight of heavy metals, more preferably from 5 to 15% by weight of heavy metals, relative to the total weight of the support and catalyst.

Generally, the amount of catalyst used in the hydroxylamine salt synthesis zone is from 0.05 to 25% by weight, preferably from 0.2 to 15% by weight, more preferably from 0.5 to 5% by weight, relative to the total weight of the inorganic process liquid in the hydroxylamine salt synthesis zone.

The average particle size of the catalyst particles is generally from 1 to 150 μm, preferably from 5 to 100 μm, more preferably from 5 to 60 μm, especially from 5 to 40 μm. By "average particle size" it is meant that 50 vol% of the particles are larger than the nominal diameter.

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

The production equipment for the preparation of hydroxylamine may be any suitable reactor, such as a reactor with a mechanical stirrer or a reactor with a working column, more preferably a reactor with a bubble column. An example of a suitable bubble column is described in NL6908934.

A typical reactor configuration capable of producing an aqueous hydroxylamine salt solution and capable of separating solid catalyst particles is a hydrogenated bubble column reactor having a cooling section. The reactor configuration often includes a plurality of sets of gas separation tubes and filter tubes.

The inorganic process liquid is fed from the hydrogenation bubble column reactor through a gas separation tube to a filter tube containing a filter element for the first step of filtration.

A quantity of the hydroxylamine salt solution filtrate (usually around 3-10%) is fed from the filter tube to the filtrate tube, and then from the filtrate tube to the filtrate buffer tube, and then from the filtrate buffer tube to the hydrazine synthesis zone. The remaining hydroxylamine salt solution filtrate (usually around 97-90%) is returned to the hydrogenation bubble column and cooled in the cooling zone. There is also a cooling device in the tube between the filter tube and the cooling section.

Detailed description of the preferred embodiment

The invention is further illustrated by the following examples, without being limited thereto.

Example 1

In accordance with a hydroxylamine phosphate oxime apparatus DSM HPO ^® technology in continuous operation, an aqueous solution containing an inorganic process liquid hydroxylamine salt solution. The average particle size of the catalyst particles (10 wt% palladium/activated carbon) was about 15 μm.

NO, NO ₂ and water are prepared in an ammonia burning apparatus, and then NO, NO ₂ and water are introduced into the absorption zone to produce nitric acid, followed by transferring the nitric acid into the reaction zone, and then reducing the nitric acid with hydrogen, thereby producing hydroxylamine.

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

Food grade nitric acid is transported, stored, transferred in containers and pipes, and reacts in the walls and walls of the vessel containing steel consisting essentially of low carbon steel B containing 0-0.03 wt% carbon and 0-0.03 wt% molybdenum. Carry out inside the container.

The content of molybdenum in the food-grade nitric acid and the produced hydroxylamine was determined by atomic absorption spectrophotometry using a Thermo Scientific iCAP6500 (ICP-AES) spectrometer or a Perkin Elmer DRC-e (ICP-MS) spectrometer.

In order to prevent the nitric acid or hydroxylamine solution in the spectrometer from crystallizing at a lower temperature, the nitric acid or hydroxylamine solution can be dissolved in water.

The measurement indicates that the content of molybdenum in the raw material solution such as food grade nitric acid (HNO ₃ ) and H ₃ PO ₄ is less than 0.1 ppm.

The measurement indicated that the content of molybdenum in the aqueous inorganic process liquid containing hydroxylamine produced was <1 ppm.

Comparative Example 2:

In Comparative Example 2, except that the wall and the pipe used were basically steel containers composed of 316 steel containing > 0.03 wt% of molybdenum, the other Example 1 was repeated.

The content of molybdenum in the produced aqueous hydroxyl-containing inorganic process liquid was determined to have produced 3-4 ppm of molybdenum and a lower hydroxylamine selectivity was observed.

Claims (11)

A process for the preparation of hydroxylamine in a continuous process in a reaction zone, the process comprising the steps of: I) burning ammonia to produce NO, NO ₂ and water; II) introducing NO, NO ₂ and water of step I) to NO, NO _{2 The} absorption zone generates nitric acid, and the nitric acid is reduced by hydrogen in the reaction zone, thereby producing hydroxylamine; and/or III) directly introducing nitric acid containing <0.1 ppm molybdenum into the reaction zone and reducing the nitric acid with hydrogen, thereby producing aqueous hydroxylammonium. Wherein the nitric acid introduced in step III) is transported, stored and transferred in a steel-containing vessel and piping; wherein the reaction is carried out in a vessel, the vessel wall and the connecting pipe comprising steel; wherein the steel contains 0-0.08 wt% carbon and 0 -0.03 wt% molybdenum. The method of claim 1, wherein the steel contains 0-0.03 wt% carbon. The method of claim 1, wherein the steel consists essentially of steel selected from the group consisting of: quench-annealed steel A comprising 0-0.08 wt% carbon, 0-2.0 wt% manganese, 0-2.0 Wt% 矽, 0-0.045 wt% phosphorus, 0-0.03 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% molybdenum, 8.0-13 wt% nickel; low carbon steel B contains 0-0.03 wt% carbon, 0 - 2.0 wt% manganese, 0-1.0 wt% bismuth, 0-0.045 wt% phosphorus, 0-0.03 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% molybdenum, 8.0-13.0 wt% nickel; Stable steel C comprises 0-0.08 wt% carbon, 0-2.0 wt% manganese, 0-2.0 wt% bismuth, 0-0.045 wt% phosphorus, 0-0.04 wt% sulfur, 17-21 wt% chromium, 0-0.03 wt% Molybdenum, 9.0-13.0 wt% nickel and or titanium (minimum: 5 times wt% carbon - max: 0.8 wt% carbon) or 铌 + 钽 (minimum: 8 times wt% carbon - max: 1.1 wt% carbon). The method of claim 1, wherein the aqueous hydrocarbon process liquid produced contains hydroxylated <3 ppm molybdenum. The method of claim 1, wherein the nitric acid added in step III comprises <0.05 ppm molybdenum. The method of claim 1, wherein in the normal operation, the ratio of the nitric acid produced in the step II) to the nitric acid added in the step III) is in the range of 100:0 to 10:90. The method of claim 1, wherein step III), without step II), continues for no more than 100 hours. The method of claim 1, wherein the step III) is continued, the step II) is not performed, and the step III) is carried out in the next step, and there is at least 2 days between the steps II). The method of claim 1, wherein the normal operation is at least every 100 hours, a) the ratio of the nitric acid produced in the step II) to the nitric acid added in the step III) is 100:0-20:80; and b) Step III) is carried out continuously without step II for a maximum of 100 hours. The method of claim 1, wherein the steel is substantially low Carbon steel B composition, the low carbon steel B comprises 0-0.03 wt% carbon, 0-2.0 wt% manganese, 0-1.0 wt% bismuth, 0-0.045 wt% phosphorus, 0-0.03 wt% sulfur, 17-21 wt% Chromium, 0-0.03 wt% molybdenum, 8.0-13.0 wt% nickel. The method of claim 1, wherein the steel is austenitic steel.