SK280951B6 - Process for selective hydration of organic nitriles - Google Patents

Abstract

Selective hydration of organic nitriles (acrylonitrile, methacrylonitrile, acetonitrile etc.) to corresponding amides is carried out at 50 - 200 C, at water-to-nitrile mole ratio ranging from 3 to 40 : 1, on a heterogeneous catalyst containing from 1 to 50 wt.% of copper or the mixture thereof with at least one oxide element that is selected from a group containing calcium, magnesium, manganese, zinc, chrome, sodium, and the residue up to 100 % contains a carrier based on silicate or alumosilicate, optionally free oxides of silicium or magnesium which are prepared by precipitating initial copper compounds (nitrates) and other elements with the content of water-glass alk.solution at pH 9 - 13, or, by ion exchange of an alk. metal or earth of copper ion zeolites followed by the treatment thereof including forming, baking and reduction. The catalyst is regenerated by oxidation prior to reduction when the decrease in its activity occurs. The amides obtained by hydration are isolated and unconverted nitriles are recycled.

Description

Technical field

The invention relates to a process for the selective hydration of organic nitriles to the corresponding amides, such as acrylonitrile to acrylamide, methacrylonitrile to methacrylamide and the like, on a specially prepared and activated heterogeneous catalyst.

BACKGROUND OF THE INVENTION

Currently, there are already technically outdated methods of hydrating organic nitriles to the corresponding amides under the catalytic effect of strong mineral acids or cation exchangers in the H-form. In addition to the considerable consumption of acid catalyst, these production processes have problems with catalyst regeneration, waste water and, last but not least, low selectivity of hydration.

However, significant technical progress has been achieved by discovering the catalytic properties of copper and other metals and their compounds for hydrating acrylonitrile to acrylamide.

The hydration of acrylonitrile to acrylamide on copper-chromium catalysts is known (US 3,597,481,

962 333 and 3 994 973), on copper-zinc-aluminum (USSR 829 621) as well as on a combined catalyst based on copper, nickel, chromium, manganese, zinc and molybdenum, as well as on other metal oxides (CA 930 377 and US

322 532). Similarly, methacrylonitrile can be hydrolyzed to methacrylamide (Zilberman EN: Uspechi chim. 1984, 53, p. 1548, however, the disadvantage is lower hydration selectivity or catalyst life. But from this point of view, the methods of hydrating acrylonitrile to Raney copper alone or with an admixture of iron, at a temperature of 70 to 200 ° C and a mole ratio of acrylonitrile: water = 60 to: 40 to 95, acrylamide is obtained in a yield of 10 to 98% (US 4,543,423 and 4,593,123; EP 175,581 and 196,099) Optionally, 3.1 O * ⁴ to 1% acetone is added to acrylonitrile (DE 3 123 037; JP 86-040 218). However, the disadvantage is the high weight of such catalysts, which increases the equipment requirements and more difficult maintains the hydration stability of nitriles when used.

Also of interest is the process of hydration of acrylonitrile to acrylamide carried out on a solid catalyst containing 30% copper, the compounds of which are dispersed in magnesium silicate (DE 2 320 060; U.S. Pat. No. 4,076,747; Mokrivsky TM et al., Chimicheskaya technologija (Kiev) 1987, 8). No. 2, p. 26). However, the rate and selectivity of hydration on catalysts of similar composition is not sufficiently reproducible, since their effectiveness depends to a large extent on the process of their preparation.

SUMMARY OF THE INVENTION

The present invention provides a process for the selective hydration of organic nitriles to the corresponding amides by treatment with water and / or water vapor at a molar ratio of H ₂ O: nitrile = 3 to 40: 1, a temperature of 50 to 200 ° C and a pressure of 0.1 to 5 MPa per copper % containing a heterogeneous catalyst, optionally with the addition of radical reaction inhibitors and / or acetone, which is carried out by passing the nitrile or nitrile mixture with water and / or steam to a heterogeneous shaped and reduced catalyst consisting of 1 to 50 wt. copper or copper mixtures with at least one oxide of an element of the group calcium, magnesium, manganese, zinc, chromium, sodium and the remainder up to 100% being a carrier based on silicate and / or alumosilicate and / or free silicon and / or magnesium oxides, prepared by ion exchange alkali metal and / or zeolite zeolite by copper ion or precipitation of multicomponent aqueous solutions at pH 9-13 and 20-70 ° C, one of which is a mixture of copper nitrate, magnesium nitrate and at least one alternating group of calcium, manganese, zinc, chromium and second sodium hydroxide carbonate alkaline water glass solution, separating, washing, drying, forming, heat treatment in an air atmosphere at 350 to 550 ° C and reducing at 150 to 300 ° C, wherein the amide is separated from the crude hydration product and the unconverted nitrile is recycled and if the catalyst activity decreases by at least 10%, this reactivates m aqueous solution of a polyvalent aliphatic alcohol, and / or by burning carbonaceous deposits with a mixture of oxygen in nitrogen with an oxygen content of 0.5 to 7.5% at 260 to 450 ° C.

The advantages of the process according to the invention are the reproducible high nitrile hydration rate and high selectivity to the corresponding amides, the stability and long life of the catalyst and its low-tech reactivation. Furthermore, the possibility of utilizing a wider range of catalysts for carrying out the process can also find use in processes other than the hydrogenation of aldehydes and carboxylic acids to the corresponding alkanols, in the hydrogenation of organic nitro compounds to the corresponding amines, and the like. Furthermore, the stabilizing effect observed on both the starting nitrile and the final amide such that it clearly does not require the addition of inhibitors. Last but not least, there is no contamination of the raw product in the process.

Injection of organic nitrile and water, resp. water vapor is most often performed separately, but especially in cases of higher water solubility of nitriles, it may be technically easier to inject them together. A higher molar excess of water is preferable to achieve a high hydration rate.

Although the hydrolysis may be carried out in a temperature range of 50 to 200 ° C, a range of 80 to 130 ° C is most suitable. At a lower temperature, the rate of hydration is clearly lower and at a higher temperature the selectivity decreases.

Possible inhibitors of the free radical reactions are mainly copper salts, polyvalent phenols and their alkyl derivatives, amines, phenothiazine, organic nitro compounds, nitrons or elemental sulfur and its compounds.

The applied catalyst for carrying out the process according to the invention is reduced with hydrogen, the most suitable nitrogen-hydrogen mixture, to avoid uncontrolled overheating of the catalyst. Useful but less suitable is reduction with hydrogen containing carbon monoxide, methane and carbon dioxide. Care should be taken that the gas applied to the reduction is as free of sulfur compounds as possible.

The catalyst can also be reduced by hydrazine or hydrogen. hydrazine hydrate. However, such a reduction is more technically and materially demanding on an industrial scale.

The copper content of the catalyst may be in the range of 1 to 50% by weight, but in the range of 8 to 38% by weight.

The heat treatment of the already dried and formed catalyst is carried out in an air atmosphere at a temperature of 350 to 550 ° C. The atmosphere may also be represented by a substantially inert gas with at least small amounts of oxygen. Temperatures greater than 550 ° C are also useful, but energy consumption is already higher and does not outweigh the improvement in catalyst quality.

Since incomplete conversion of nitriles is often used, recycling is desirable. According to the method of the present invention, with virtually complete conversion of nitriles into one catalyst passage, of course, nitrile recirculation is omitted.

Activation of the catalyst is accomplished with polyhydric alcohols such as monosaccharides, ethylene glycol, aqueous pentaerythritol, and the like. However, it is more efficient to burn carbonaceous deposits on the catalyst with a nitrogen-oxygen mixture at a temperature of 260 to 460 ° C. The oxygen content may also be higher, especially towards the end of firing, but the defined range is suitable from a safety point of view.

The process according to the invention is preferably carried out continuously; however, it can also be carried out semi-continuously and continuously, especially in the case of higher molecular nitriles or organic substances containing more nitrile groups in the molecules. In such a case, however, it is usually also convenient to use a solvent, in particular aprotic.

Further data on carrying out the process of the invention as well as other advantages are apparent from the examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Precipitating solutions are prepared in two beakers, namely solution (a) containing 266 g of crystalline copper nitrate, 264 g of crystalline magnesium nitrate and either 46.3 g of crystalline calcium nitrate or 46.3 g of crystalline manganese nitrate or 64.3 g of crystalline nitrate chromium. In a second beaker solution (b), which is an alkalized aqueous water glass solution containing 310.7 g of aqueous sodium glass having a concentration of 25% by weight of silica, 150 g of sodium hydroxide and 80 g of sodium carbonate (anhydrous).

Weigh 700 g of distilled water, made alkaline with sodium hydroxide to a pH = 11.5, into a 2 dm ³ beaker. Precipitating solutions (a, b) are then simultaneously added to the vigorously stirred water from the two beakers. The precipitation takes place at a pH of approximately 11. A precipitate - suspension of catalyst mass is withdrawn semi-continuously from the precipitation vessel so that the total volume of the suspension during precipitation is approximately constant. The precipitate thus obtained is then separated from the mother liquor on the filter and washed thoroughly with demineralized water at a temperature of 65 to 85 ° C. The filter cake is dried at 115-120 ° C for 12 h, ground and mixed with 2 wt. graphite and stablet. The obtained 5 x 5 mm tablets are further calcined at 500-520 ° C for 4 h.

Thus, 2 samples of a tableted catalyst of hydration of organic nitriles to the corresponding amides are obtained. Thus, catalyst K is 35 wt. Cu, Mn, Ca, Na and the remainder to 100 = SiO ₂ and K ₂ , also containing 35 wt. Cu, but chromium trioxide is present instead of manganese oxide.

The mechanical strength of the granules of catalyst] = 34.5 MPa, and K ₂ = 30.1 MPa.

The reaction conditions and the achieved hydration results of the various nitriles on the above catalysts at a water / nitrile molar ratio = 8 are given in Table 1.

Table 1

Τ * υΠα1

KatoipteM lUtUai tspun rci THK [MF. | Ztťkbw · (W / F) nitrile Kea «trú nilnb t% l The -R- IJ 1.1 koíoimM ¹ «.i K. well 0 » M NMM I9O K 190 M U KMUL 1 » K 110 IN U iMtakryi » WJ K. 100 0.7 at MTNL 9 3 * K 10 » 0 » at lisylaailril 07,9 K. 100 0.7 1.1 OMtokyt »Kym • 23 *

^{a) The} selectivity to acetamide is 70 to 78%. In other hydrations, the selectivity to amides is 98-100%.

Example 2

Weigh 39.8 g of crystalline copper nitrate, 36.8 g of crystalline magnesium nitrate and 5.2 g of crystalline calcium nitrate into a 2 dm ³ beaker and add 530 g of distilled water. To this solution is added, with stirring, an 8% w / w alkalized waterglass solution containing 43.7 g of 25% w / w sodium waterglass. and 24.4 g of sodium hydroxide. Precipitation resulted in a light-white, finely dispersed precipitate, with the mother liquor having a pH of 10.95 at the end of the precipitation. After standing for 2.5 h, the precipitate-suspension was filtered off, washed well with distilled water at 65-85 ° C. The filter cake is then dried for 12 h in an oven at 107-120 ° C. The mass thus obtained is ground, homogenized with 2 wt. graphite and then tableted. The tablets are further calcined at 350 to 365 ° C for 3.5 h and further at 490 to 520 ° C for 1 h. The tablets obtained contained 35.1 wt. Cu, mainly in the form of oxide, Mg, Ca and partly Na also in the form of oxides, the rest being SiO ₂ . The mechanical strength of the tablet changes 5x5 mm to 29.1 MPa. This catalyst is effective in catalysing the hydration of organic nitriles to the corresponding amides (K ₃ catalyst).

Example 3

By the ion exchange method [Sodesawa T .: React. Kinet. and Catal. Lett. 1986, 32, no. 1, p. 51-56, 63-69 (1986)] are prepared on supported SiO ₂ , ZrO ₂ and TiO ₂ copper catalysts containing 1.5 wt. Cu. Thus, the catalyst Cu - SiO ₂ (K i), Cu - ZrO ₂ (K _s ) and Cu - TiO ₂ (K s).

Example 4

The procedure is analogous to Example 2, except that the weight changes. component ratios. The obtained tableted Cu-silicalite component contains (in weight%): 39.4 CuO, 10.9 MgO, admixtures of chromium compounds (on the order of 10 ' ³ %), iron (on the order of 10' ² %), chromium (on the order of 10 ' ³⁾ %), nickel and cobalt (of the order of 10 ' ³ %). Catalyst (K ₇ ) effectively catalyzes the hydration of organic nitriles to the corresponding amides.

Following a procedure the produced catalyst (C _8), but with an increased content of a medium containing 49.1% by weight.

Example 5

A 25 cm diameter, 600 mm long glass jacket reactor equipped with a heating mantle, temperature measurement and gas metering is charged with 75 cm ^{3 of the} tableted catalyst K 1 specified in Example 1. A 1: 1 hydrogen / nitrogen mixture is charged into the reactor. in an amount of 230 cm ³ .min ^-1 and the reactor was slowly heated to 150 ° C. Under these conditions, the reduction of the catalyst takes place for 8 hours and is then metered in at 350 cm ^{3 /} min. ¹ for 13 h. In the last phase, for 3 hours, 350 cm ^{3 of} hydrogen are still added. ¹ and the catalyst is reduced at 200 ° C. 9.5 g of water are condensed from the gas phase at the reactor outlet. The reactor is then allowed to cool to room temperature in a stream of hydrogen or a nitrogen-hydrogen mixture and is flooded with demineralized water. It is thus stored to prevent oxidation of the catalyst. The catalyst is ready for use in the hydration of organic nitriles to the corresponding amides in liquid or vapor phase.

Similarly, the other catalysts of Examples 1 to 4 are activated.

Example 6

A tube reactor made of stainless steel, equipped with temperature control jacket and temperature, pressure control, condenser, storage of raw materials and the product, the diameter of the tube 29 mm and a length of 1 000 mm was poured 80 g of tablet of copper silicate catalyst of _B prepared as described in Example 1 and activated according to the procedure of Example 5. The catalyst was quenched with demineralized water and the reactor pressure was adjusted to 60 psi with nitrogen pressure. A piston pump, the dose will acrylonitrile, stabilized with 1.10 ^"3% by weight. a polymerization inhibitor. Acrylonitrile is dosed at 8.4 g / h and demineralized water at a rate of 31.6 g / h through the second pump, so that a total of 40 g / h acrylonitrile / water (W / F = 2) containing 21% by weight is added to the catalyst. . acrylonitrile. The catalyst reactor is heated to 100 ° C. Samples shall be taken from the container at specified time intervals and weighed and analyzed. They determine the content of acrylonitrile, acrylamide, by-products and optionally polymers.

During the 8 h experiment, the conversion of acrylonitrile reached 99%, but was not present in the crude hydrolyzate in an amount above 0.1% by weight. neither ethylene cyanohydrin nor acrylic acid as potential by-products. The polymer content also did not exceed 0.1%. After 100 h steady state, the conversion of acrylonitrile was 90-91%.

After reactivation of the catalyst with an aqueous solution of a sorbitol / glucose mixture at 4 wt. for 40 min. the conversion of acrylonitrile reaches 94-97% in 40 h. However, if, in addition, the catalyst is reactivated by burning in air at 380 to 440 ° C followed by reduction with hydrogen with impurities (3,4% CO, 0,5% CO ₂ and 2% CH ₄ ) at temperature 200 to 250 ° C for 40 min., When used for the hydrolysis of acrylonitrile for at least 200 h, the conversion of acrylonitrile is 99% and the selectivity to acrylamide is 97 to 99%.

Similar results are also obtained on activated catalysts K ₂ , K ₃ and K ₇ .

Example 7

The procedure is similar to that of Example 6, but K ₃ and K ₇ activated by the procedure of Example 5 are applied as catalysts. In addition, the effect of temperature and initial acrylonitrile concentration in water on its hydration on acrylamide is investigated. The results are summarized in Table 2.

Table 2

Tibulk> 2

catalyst Temperature * Reactor » [° C] Pressure (MPa) W / F Concentration of acrylonitriles in mixture with water [wt.%] conversion K 80 0.6 2.0 7.0 K BO 0.6 2.0 7.0 99.5 90 0.6 2.0 14.0 89.5 K 90 0.6 2.0 14.0 89.9 Κ » 100 0.6 2.0 21.0 92.7 K 100 0.6 2.0 21.0 92.5 K 100 0.6 2.0 21.0 96.3 k, well 0.6 2.0 21.0 99.7 K. 120 0 ,? 2.0 21.0 100.0

Example 8

The procedure is as in Examples 6 and 7, except that the catalysts K ₄ , K ₅ and K _{6, as} described in Example 3, are activated as described in Example 5. The results obtained are summarized in Table 3.

Table 3

T * uľkí3

catalyst Reaction temperature ± 2 (° C] pressure [MPa] W / F Initial dance and jay [% w / w] Koo version of acryiotite (H) K. 100 M (U 14.0 9U K well 0.1 0.2 14.0 92.6 K. HO of 8 0.2 14.0 91.6

Example 9

Activated catalyst K _{3 is} charged into the reactor described in Example 6. The reactor is flooded with distilled water and doses was 75 cm ^"3 .h" ¹ demineralizovatiej of water and 39 cm @ ¹ .h methacrylonitrile containing 10.1 ^"3% by weight. inhibitor. The temperature is raised up to 120 ° C, the nitrogen pressure is maintained at 0.8 MPa. At steady state, the conversion is 65 ± 2% at virtually complete selectivity to methacrylamide.

Example 10

Into a continuous reactor, characterized in Example 6 were seeded 80 g of activated copper-silicate catalyst to _7th Injection of acrylonitrile in water containing 14 wt. The acrylonitrile is 40 g / h (W / F = 2) at 80 ° C and 0.8 MPa.

At steady state, the conversion of acrylonitrile is 92% after 20 hours and 90% after 100 hours. The presence of by-products including polymers <0.1 wt.

Example 11

A mixture of 40 g / h of water and nicotinitrile (each separately) is injected at 120 ° C and 0.9 MPa into a continuous reactor, as described in Example 6, with activated copper-silicate catalyst K ₂ , at an acid nitrile content of 40 g / h. % of the nicotine in the mixture is 15 wt. The conversion reached 88% and the selectivity to nicotinic amide 97%.

Example 12

A mixture of 40 g / h of water and acetonitrile (each component separately) is injected into the continuous reactor described in Example 6 and with activated copper-silicate catalyst K ₃ at 110 ° C and 0.8 MPa, the acetonitrile content of the mixture being 14 wt. The acetonitrile conversion was 99% and the acetamide selectivity was 97%.

Example 13

The procedure is as in Example 12, but as the acetonitrile conversion decreases to 84%, the catalyst is reactivated by rinsing with an aqueous solution of sorbitol at a concentration of 6% by weight. for 20 min. and then fired in a stream of nitrogen containing 3.7% by volume. of oxygen at 320 to 340 ° C for 30 min. and then reduced with a nitrogen-hydrogen mixture at 190 to 210 ° C for 3 h.

Upon re-injection of acetonitrile, its conversion is 99%.

A similar 8 wt% aqueous glucose solution and a 2 wt% aqueous solution have a similar reactivating effect. mixtures of pentaerythritol and dipentaerythritol. After reactivation, the acetonitrile conversion is 94-100% and the acetamide selectivity is 97-100%. The acetonitrile conversion decreases below 94% after 100 h of hydration. However, when reactivated with an aqueous solution of one of the above-mentioned polyhydric alcohols, followed by firing of the catalyst with a mixture of 94 vol. nitrogen and 6% vol. of oxygen at a temperature of 350 + 100 ° C for 1 h, followed by reduction with hydrogen containing 4.3% v / v as components. CO and 1.2 vol. CO ₂ at 200 ± 30 ° C for 90 min. or at 270 ± 30 ° C for 45 min., the need for further reactivation of the catalyst is at least 250 h in operationIndustrial availability

The process of the present invention is particularly useful in the chemical and pharmaceutical industries in the production of amides by selective hydration of nitriles.

Claims (2)

A process for the selective hydration of organic nitriles to the corresponding amides by treatment with water and / or water vapor at a molar ratio of H ₂ O: nitrile = 3 to 40: 1, a temperature of 50 to 200 ° C and a pressure of 0.1 to 5 MPa on copper containing heterogeneous % of a catalyst, optionally with the addition of radical reaction inhibitors and / or acetone, characterized in that the nitrile or mixture of nitriles is fed with water and / or steam to a heterogeneously shaped and reduced catalyst consisting of 1 to 50 wt. copper or copper mixtures with at least one oxide of an element of the group calcium, magnesium, manganese, zinc, chromium, sodium and the remainder up to 100% being a carrier based on silicate and / or aluminosilicate and / or free silicon and / or magnesium oxides, prepared by ion exchange alkali metal and / or earth from zeolite by copper ion or by precipitation of multicomponent aqueous solutions at pH 9-13 and 20-70 ° C, one of which is a mixture of copper nitrate, magnesium nitrate and at least one alternating group of calcium, manganese, zinc, chromium and second sodium hydroxide carbonate alkaline water glass solution, separating, washing, drying, forming, heat treatment in an air atmosphere at 350 to 550 ° C and reducing at 150 to 300 ° C, wherein the amide is separated from the crude hydration product and the unconverted nitrile is recycled and reactivates when the catalyst activity decreases by at least 10% m of an aqueous solution of a polyhydric aliphatic alcohol and / or by burning the carbonaceous deposits with an oxygen-nitrogen mixture having an oxygen content of 0.5 to 7.5% at a temperature of 260 to 450 ° C. Process according to claim 1, characterized in that the reduction of the fresh heterogeneous catalyst or after reactivation with a polyhydric alcohol and / or by burning of carbonaceous deposits is carried out by reduction with hydrogen or hydrogen-containing gas at a temperature of 150 to 300 ° C, preferably at 175 to 300 ° C. 230 DEG.