DE102004042947A1 - Continuous production of xylylenediamine comprises mixing phthalonitrile melt stream with liquid ammonia stream and hydrogenating the liquid mixture - Google Patents

Abstract

Continuous production of xylylenediamine comprises mixing a phthalonitrile melt stream with a liquid ammonia stream and feeding the liquid mixture into a hydrogenation reactor containing a heterogeneous catalyst.

Description

The The present invention relates to a process for the preparation of Xylylenediamine by continuous hydrogenation of liquid phthalonitrile on a heterogeneous catalyst in the presence of liquid ammonia in a reactor.

xylylenediamine (Bis (aminomethyl) benzene) is a useful starting material, e.g. for the Synthesis of polyamides, epoxy hardeners or as an intermediate for the preparation of isocyanates.

The Name "xylylenediamine" (XDA) includes the three isomers ortho-xylylenediamine, meta-xylylenediamine (MXDA) and para-xylylenediamine.

Of the Term "phthalonitrile" (PDN) includes the three isomers of 1,2-dicyanobenzene = o-phthalodinitrile, 1,3-dicyanobenzene logo CNRS logo INIST Isophthalonitrile = IPDN and 1,4-dicyanobenzene = terephthalodinitrile.

The Phthalonitriles are solids (e.g., isophthalonitrile melts (IPN) at 161 ° C) and have relatively poor solubilities in organic solvents on.

The two-step synthesis of xylylenediamine by ammoxidation of Xylene and subsequent Hydrogenation of the resulting phthalonitrile is known. unreacted Dinitriles are very difficult to separate from the XDA by distillation.

US Patent No. 4,482,741 (UOP Inc.) describes the hydrogenation of PDN in the presence of ammonia, a specific catalyst and XDA as solvent.

In MXDA is the solubility of IPDN at 70 ° C about 20 wt .-%.

EP-A2-1 193,247 and EP-A1-1 279 661 (both to Mitsubishi Gas Chem. Comp.) a process for the purification of isophthalonitrile (IPDN) or a Process for the preparation of pure XDA.

EP-A2-1 193 244 (Mitsubishi Gas Chem. Comp.) Describes a process for Production of XDA by hydrogenation of phthalonitrile, which synthesized in a previous stage by ammoxidation of xylene is, where the vapor Product of the ammoxidation stage directly with a liquid organic solvent is brought into contact (quench) and the resulting quench solution or suspension fed to the hydrogenation becomes.

Preferred organic solvents are C ₆ -C ₁₂ aromatic hydrocarbons, such as xylene and pseudocumene (column 6, paragraphs [0027] and [0028]).

US-A-3,069,469 (California Research Corp.) teaches as a hydrogenation solvent of aromatic nitriles, such as PDN, aromatic hydrocarbons, Xylene, dioxane and aliphatic alcohols.

DE-A-21 64 169 (Mitsubishi Gas Chemical Co., Inc.) describes on page 6, last paragraph, the hydrogenation of IPDN to meta-XDA in the presence a Ni and / or co-catalyst in ammonia as a solvent.

GB-A-852.972 (Equivalent to: DE-A-11 19 285) (BASF AG) discloses the use of ammonia and XDA as a solvent in the hydrogenation of PDN. The preparation of the educt solution starting from solid PDN is carried out in an extra step in a separate vessel (cf. Page 2, lines 119-120).

JP-A-2003-327563 (Mitsubishi Gas Chem. Co., Inc.) relates to a process for the fixed bed hydrogenation of aromatic Dinitriles, which are used as 1-10 wt .-% solutions.

The six German patent applications with file number 10341615.3, 10341632.3, 10341614.5, 10341633.1, 10341612.9 and 10341613.7 (BASF AG) from 10.09.03 relate to each method for the production of XDA.

A parallel German patent application with the same filing date (BASF AG) relates to a process for the production of XDA by continuous hydrogenation from liquid Phthalonitrile on a heterogeneous catalyst in the presence of liquid ammonia in a reactor where part of the reactor effluent is a liquid recycle stream is continuously fed back to the reactor inlet (circulation mode), in which by means of a mixer, a stream of a Phthalodinitrilschmelze liquid is fed into the circulation stream around the hydrogenation reactor, wherein the phthalonitrile conversion in the reactor in single pass greater than 99% is, and the recycle flow to greater than 93 wt .-% from liquid Ammonia and xylylenediamine and no other solvent for phthalonitrile contains.

In the various processes for the preparation of phthalonitrile, this precipitates as a solid or dissolved in a solvent, for example pseudocumene, or as a melt. The handling of solids is usually difficult and cumbersome. The further processing in a solvent requires because of the low solubility of phthalonitrile in solvents such as o-xylene, m-xylene, p-xylene, pseudocumene, mesitylene, ethylbenzene or methylpyridine very large amounts of solvent which must be separated by distillation tion usually by distillation , which - corresponding to the large flow rates - requires large equipment and a high energy consumption. Alternatively, an ex traction of the PDN with water followed by distillation. Again, the energy consumption is great because the water distilled off and the solvent - at least in the partial flow - must be regenerated.

Of the Present invention was based on the object, an improved economical process for the preparation of xylylenediamine, in particular meta-xylylenediamine, with high selectivity, Yield and space-time yield (RZA) to find, which in with Prior art methods due to comparable throughputs reduced material flows, in particular solvent streams, including recycle streams, reduced and / or fewer apparatus and machines.

Accordingly, became a process for the preparation of xylylenediamine by continuous Hydrogenation of liquid Phthalonitrile on a heterogeneous catalyst in the presence of liquid ammonia found in a reactor, which is characterized in that by means of a mixing device, a stream of a Phthalodinitrilschmelze liquid into a stream of liquid Ammonia is fed in and the liquid mixture in the hydrogenation reactor is driven.

Prefers finds the method according to the invention Use for the production of meta-xylylenediamine (MXDA) by hydrogenation of isophthalonitrile (IPN), which in particular in a previous Stage was synthesized by ammoxidation of meta-xylene.

The molten phthalonitrile may, for example, one of a Ammonoxidation downstream quench, an evaporation stage or a distillation column, the phthalonitrile being e.g. each as a melt over Bottom of these thermal separation apparatus is separated, such. in German Patent Application No. 10341633.1 of 10.09.03 (BASF AG).

alternative can in the process according to the invention also used molten, previously present as a solid PDN become. The melting can e.g. done by means of an extruder.

advantage The dosing of the PDN as a melt in the liquid ammonia is that the phthalonitrile already diluted immediately after mixing and at significantly reduced Temperature is present before using xylylenediamine (from the optional Circulating or formed in the hydrogenation reactor) comes into contact, whereby an unwanted reaction between nitrite and product can be largely suppressed. In addition, can the melt dosage is carried out at a pressure which is less than the reactor pressure, creating a more cost-effective melt pump used can be. The solution can then follow to the desired reactor pressure be compressed.

The Drive and release the phthalonitrile melt in liquid ammonia requires a mixing device, preferably a mixing nozzle, which realized in the simplest case by a pipe tee can be. Preferably, the nozzle mouth has a taper.

The streams are fed separately and in the subsequent Pipe mixed and homogenized due to the prevailing turbulence. Advantageously, in addition be followed by a static mixer. It will not be additional Apparatus, such as a stirred tank to release of (solid or liquid) Phthalonitrile in a solvent needed.

Prefers is the mixing device at the place of phthalonitrile feed into the Stream of liquid ammonia to a temperature in the range of 1 to 40 ° C, especially in the range of 5 to 25 ° C, heated above the melting point of the phthalonitrile used.

Prefers the PDN supply occurs practically at an absolute pressure between 15 bar and the reactor pressure. The minimum pressure results from the particular preferred boundary condition that in the mixing and the adjusting mixing temperature no evaporation occurs, but the mixture is liquid remains. He is thus on the starting temperature and the ratio of dependent on mixing components. Mixing at low pressure, e.g. 40 bar, offers the advantage that the melt pump is not for the much higher Reactor pressure must be designed. The PDN solution in ammonia must be in this Case, however, still by means of a - constructive simpler - high pressure pump be compressed to the reactor pressure. The latter can be omitted if the mixing already takes place at reactor pressure. Which variant is preferable depends on availability the apparatus and machines as well as economic aspects.

Especially is preferred by means of a mixing nozzle as a mixing device that liquid Phthalonitrile is injected into the stream of liquid ammonia.

A preferred embodiment of the mixing nozzle is in 2 shown in the appendix. The heating of the mixing nozzle can be done for example with steam, heat transfer oil or electric.

The inlet of the liquid ammonia can be carried out via one or more radially or tangentially mounted nozzle, eg as in the 3 shown.

Important is the locally high flow rate (high pulse current and turbulence), allowing fast mixing (Homogenization) occurs. With laminar flow of mass transfer ranges to homogenize and the currents are insufficient mixed (streaking).

suitable mixing nozzles are e.g. in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. B4, pp 565-569.

In a preferred embodiment the method according to the invention Part of the reactor discharge is continuous as a liquid recycle stream returned to the reactor inlet (circulation mode) and the liquid Mixture of ammonia and phthalonitrile in the recycle stream to fed to the hydrogenation reactor, wherein the recycle stream to greater than 93 wt .-% from liquid Ammonia and xylylenediamine exists.

By Applying a circulation stream, the phthalodinitrile solution can continue dilute or the amount of fresh ammonia can be reduced. In any case In the reactor, a high ammonia concentration is reached, resulting in turn cheap on the selectivity effect.

The inventive method is in an advantageous embodiment further characterized in that the reactor mixture no further solvent for phthalonitrile contains.

The phthalonitrile conversion in the hydrogenation reactor in a single pass is preferably greater than 99%, especially greater than 99.5%, very particularly greater than 99.9%, in particular greater than 99.95%, very particularly greater than 99.97%. In the hydrogenation reactor is thus driven by appropriate adjustment of the reaction conditions (pressure, temperature, molar ratios of PDN, NH ₃ and H ₂ , catalyst, flow rates, residence time in the reactor) virtually full conversion.

Prefers is the liquid one Circulating flow (according to the process variant with circulation mode) to greater than 94 wt .-%, in particular greater than 95% by weight, especially greater than 96% by weight, from liquid Ammonia and xylylenediamine; the rest are secondary components.

In addition to components in the liquid Circulating flow (circulating stream) can By-products formed in the reaction and dissolved gases and secondary components added to the phthalonitrile, however no further solvent, e.g. organic solvent, for phthalonitrile be.

Of the Circulating flow (according to the process variant with circulation mode) contains preferably in the range from 25 to 90% by weight, especially from 30 to 70% by weight, in particular 45 to 60 wt .-%, liquid ammonia.

Of the Part of the liquid Reaktoraustrags, the (according to the process variant with circulation mode) as a circulation stream continuously to the reactor inlet is attributed preferably accounts for 20 to 95 wt .-%, especially 50 to 92 wt .-%, in particular 75 to 90% by weight, of the total liquid Reaktoraustrags from.

The weight ratio of phthalonitrile / ammonia feed stream to recycle stream (according to the process variant with circulation mode) is preferably in the range of 0.05 to 5, especially in the range of 0.1 to 2.0, especially in the range from 0.15 to 1.0.

The Reaction temperature is preferably in the range of 40 to 150 ° C, especially preferably 60 to 135 ° C, in particular 70 to 130 ° C.

The Amount of ammonia, the amount of optionally available circulation stream (according to the process variant with Kreislauffahrweise) and the reactor inlet temperature are so set the reactor outlet temperature to the desired maximum value (e.g., 130 ° C) does not exceed because with increasing temperature reinforced by-products formed become. The reactor feed temperature is adjusted (e.g. An additional Heat exchanger or, preferably, by suitably adjusting the temperature of to be mixed streams) that the reaction proceeds sufficiently fast and reaches full turnover becomes. By variation of circulating flow rate or fresh flow rate with ammonia it is thus possible set both inlet and outlet temperature of the reactor and optimally adapted to the ongoing reactions and thus the XDA yield to optimize.

The Hydrogenation is preferred at an absolute pressure in the range of 100 to 300 bar, in particular 120 to 220 bar, especially 150 up to 200 bar, performed.

For the hydrogenation can known in the art catalysts and reactors (in particular Tube reactors or tube bundle reactors; Fixed bed or suspension mode).

In the fixed catalyst bed mode, both the sump and the trickle mode are possible Lich. Preferred is a trickle way.

Prefers the reactor is operated adiabatically, while the resulting heat of reaction via a recirculating cooler installed and optionally with the verwen Deten circulating gas is discharged. This elevated additionally the selectivity the reaction by the further suppression of by-products.

alternative but is also a cooled Reactor, for example, a tube bundle reactor used.

Prefers are catalysts, the cobalt and / or nickel and / or iron, as Full catalyst or on an inert support.

Especially The hydrogenation is preferably carried out on a manganese-doped cobalt unsupported catalyst.

Suitable catalysts are, for example, Raney nickel, Raney cobalt, Co full contact, titanium-doped cobalt supported (JP-A-2002 205980), Ni supported on SiO ₂ (WO-A-2000/046179), Co / Ti / Pd on SiO _{2 support} (CN-A-1 285 343, CN-A-1 285 236) and nickel and / or cobalt on zirconia support (EP-A1-1 262 232).

Examples for further suitable catalysts are found e.g. in applications GB-A-852,972 (equivalent: DE-A-11 19 285) (BASF AG), DE-A-12 59 899 (BASF AG) and the US patents No. 3,069,469 (California Research Corp.) and 4,482,741 (UOP Inc.).

Especially preferred catalysts are those disclosed in EP-A1-742 045 (BASF AG) Cobalt full contacts doped with Mn, P, and alkali metal (Li, Na, K, Rb, Cs). The catalytically active composition of these catalysts before reduction with hydrogen from 55 to 98 wt .-%, in particular 75 to 95 wt .-%, cobalt, 0.2 to 15 wt .-% phosphorus, 0.2 to 15 Wt .-% manganese and 0.05 to 5 wt .-% alkali metal, in particular sodium, each calculated as oxide.

Further suitable catalysts are the catalysts disclosed in EP-A-963 975 (BASF AG), whose catalytically active composition before treatment with hydrogen contains from 22 to 40% by weight ZrO ₂ ,
1 to 30% by weight of oxygen-containing compounds of copper, calculated as CuO, 15 to 50% by weight of oxygen-containing compounds of nickel, calculated as NiO, the molar Ni: Cu ratio being greater than 1,
15 to 50% by weight of oxygen-containing compounds of cobalt, calculated as CoO, 0 to 10% by weight of oxygen-containing compounds of aluminum and / or manganese, calculated as Al ₂ O ₃ or MnO ₂ ,
and contains no oxygen-containing compounds of molybdenum,
for example, the one in loc. cit., page 17, disclosed catalyst A having the composition 33 wt% Zr, calculated as ZrO ₂ , 28 wt% Ni, calculated as NiO, 11 wt% Cu, calculated as CuO and 28 wt%. % Co, calculated as CoO,
the
in EP-A-696 572 (BASF AG) disclosed catalysts whose catalytically active material prior to reduction with hydrogen from 20 to 85 wt .-% ZrO ₂ , 1 to 30 wt .-% of acid-containing compounds of copper, calculated as CuO, 30 to 70 wt .-% oxygen-containing compounds of nickel, calculated as NiO, 0.1 to 5 wt .-% oxygen-containing compounds of molybdenum, calculated as MoO ₃ , and 0 to 10 wt .-% oxygen-containing compounds of aluminum and / or Manganese, calculated as Al ₂ O ₃ or MnO ₂ , contains, for example, in loc. cit., page 8, disclosed catalyst having the composition 31.5 wt .-% ZrO ₂ , 50 wt .-% NiO, 17 wt .-% CuO and 1.5 wt .-% MoO ₃ ,
and the catalysts described in WO-A-99/44984 (BASF AG) comprising (a) iron or a compound based on iron or mixtures thereof, (b) from 0.001 to 0.3% by weight, based on (a ) of a promoter on the basis of 2, 3, 4 or 5 elements selected from the group Al, Si, Zr, Ti, V, (c) from 0 to 0.3 wt .-% based on (a) of a compound the base of an alkali and / or alkaline earth metal, and (d) from 0.001 to 1 wt .-% based on (a) manganese.

The process according to the invention can be carried out, for example, as follows:
In 1 a possible arrangement of the hydrogenation reactor including the optional circulation circuit and a heat exchanger is shown. The phthalonitrile melt is used as stream [ 1 ] and with the liquid ammonia [ 2 ] mixed. The mixture is mixed either with the optionally available circulation circuit [ 4 ] mixed or fed directly to the reactor. For better mixing with the circulation circuit, for example, a static mixer can be used.

Hydrogen and possibly recycle gas can be heated to the desired reactor inlet temperature by means of an optional heat exchanger. Gas and liquid can be fed together or - preferably - separated to the reactor. Preferably, the temperature of the streams to be mixed is adjusted by means of heat exchangers so that no heat exchanger is required behind the mixing point. In the reactor, the hydrogenation is virtually quantitative, so that virtually no phthalonitrile is present in the reaction. The reaction can then be cooled, and gas and liquid are pressurized in a High pressure separator separated. In the case of the circulation liquid method, a part of the liquid from the reaction discharge is circulated without work-up (stream [ 4 ]). Otherwise, the reaction output of the work-up (stream [ 9 ]). Part of the gas is discharged to avoid accumulation of inerts (CO, N ₂ , CH ₄ , noble gases, etc.). Most of the gas is returned via a compressor to the reactor inlet. If the pressure drop in the reactor is not too high, an ejector jet nozzle ("water jet pump") can be used for this purpose.The total quantity of circulating gas can be varied within wide ranges, for example from several times the amount of fresh gas to zero (operating mode without cycle gas) in order to charge the reactor sufficiently on the gas side for a good mass transfer and to provide a sufficient drag flow for inert gases in order to be able to discharge them at the reactor outlet In addition, a portion of the heat of reaction can be removed with the gas stream Amount of ammonia, which further enhances the cooling effect of the recycle gas. 9 ]) is then first fed to a pressure distillation, in which liquid ammonia overhead (stream [ 10 ]) and largely ammonia-free, crude xylylenediamine via sump (stream [ 11 ]), wherein the ammonia can be fed in condensed form back to the hydrogenation stage. The crude xylylenediamine is further purified, for example by distillation.

In the process according to the invention, the weight ratio of the fresh feeds of dinitrile and ammonia (for example, according to. 1 the ratio of current [ 1 ] to current [ 2 ]), the larger the circulation flow (according to the process variant with circulation mode of operation), the greater the chosen. The ammonia flow is limited downwards by the solubility of PDN in liquid ammonia at the given temperature (eg, the solubility of IPN in NH ₃ at 40 ° C is about 45% by weight.). The starting material weight ratio of dinitrile to ammonia is preferably 1: 0.5 to 1:10, preferably 1: 0.6 to 1: 5, more preferably 1: 0.9 to 1: 3.5.

at the driving style without circulating fluid is the feed weight ratio from dinitrile to ammonia preferably 1: 2.5 to 1: 100, preferably 1: 4 to 1:13, more preferably 1: 5 to 1:10.

Isolation of the XDA:

To In the hydrogenation, the ammonia used is separated off, e.g. distilled off.

Prefers Purification of xylylenediamine by distilling off lower-boiling by-products (at the same pressure) over Head and distillative removal of heavy-boiling impurities via bottom.

Especially preferred is the driving style, in which after hydrogenation the Ammonia and possibly overheads by low-boiling by-products distilled off and then heavy-boiling impurities of xylylenediamine distillatively over swamp separates.

In a particular embodiment can the separation of light and heavy-boiling by-products also take place in a Seitenabzugs- or dividing wall column, wherein pure xylylenediamine over a liquid or gaseous Side take is won.

ever according to the desired Purity is the product (XDA) in addition to an organic Solvent, preferably an aliphatic hydrocarbon, in particular a cycloaliphatic hydrocarbon, especially cyclohexane or Methylcyclohexane, extracted.

These Purification by extraction may e.g. according to DE-A-1 074 592 (BASF AG) respectively.

Examples

Example 1:

90 g / h of molten IPDN (commercial, scaled IPDN, which by heating to about 170 ° C was melted) were by means of a pipe tee with 90 g / h of fresh ammonia dissolved. This corresponds to the solubility at 45 ° C. The calculated mixing temperature with ideal mixing is 74 ° C, if ammonia at 25 ° C is added. The boiling pressure is 32.3 bar (abs.), I. above At this pressure, the mixture remains liquid and there is no evaporation held by ammonia. The solution was in a circulation stream (about 1000 g / h) consisting of the liquid recycle stream the reactor discharge drove. The resulting reaction mixture was continuously in a tubular reactor on a cobalt full contact at 90 ° C and 200 hydrogenated bar. The withdrawn part of the reactor effluent was in a Ammonia column of the majority The amount of ammonia released and analyzed by GC. At full conversion of the IPDN used (i.e., greater than 99.95 %; By GC, no starting material detectable), the selectivity was 93%.

In subsequent distillation steps, residual ammonia and low-boiling secondary components were first separated off. After removal of the high-boiling impurities via bottom MXDA was the top product of a distillation column in a purity of more than 99.9 wt .-% obtained.

Example 2:

90 g / h of molten IPDN (commercial, scaled IPDN, which by heating to about 170 ° C was melted) were by means of a pipe tee with 270 g / h of fresh ammonia dissolved. The calculated mixing temperature with ideal mixing is 52 ° C, if ammonia at 25 ° C is added. The boiling pressure is 20.5 bar (abs.), I. above At this pressure, the mixture remains liquid and there is no evaporation held by ammonia. The solution was in a circulation stream (about 900 g / h) consisting of the liquid recycle stream the reactor discharge drove. The resulting reaction mixture was continuously in a tubular reactor on a cobalt full contact at 90 ° C and 200 hydrogenated bar. The withdrawn part of the reactor effluent was in a Ammonia column of the majority The amount of ammonia released and analyzed by GC. At full conversion of the IPDN used, the selectivity was 95 %.

In subsequent Distillation steps were first residual ammonia and low boiling Separate secondary components. After removal of the high-boiling impurities via the bottom was MXDA as the top product of a distillation column in a purity of more than 99.9% by weight.

Example 3:

90 g / h of molten IPDN (commercial, scaled IPDN, which by heating to about 170 ° C was melted) were by means of a pipe tee with 600 g / h of fresh ammonia dissolved. The calculated mixing temperature with ideal mixing is 41 ° C, if ammonia at 25 ° C is added. The boiling pressure is 16 bar (abs.), I. above At this pressure, the mixture remains liquid and there is no evaporation held by ammonia. The obtained reaction mixture became continuous in a tubular reactor on a cobalt full contact at 90 ° C and 200 hydrogenated bar. The withdrawn part of the reactor effluent was in an ammonia column from the majority the amount of ammonia freed and over GC-examined. At full conversion of the IPDN used, the selectivity was 93 %.

In subsequent Distillation steps were first residual ammonia and low boiling Separate secondary components. After removal of the high-boiling impurities via the bottom was MXDA as the top product of a distillation column in a purity of more than 99.9% by weight.

Claims (23)

A process for the preparation of xylylenediamine by continuous hydrogenation of liquid phthalonitrile on a heterogeneous catalyst in the presence of liquid ammonia in a reactor, characterized in that by means of a mixer, a stream of a Phthalodinitrilschmelze liquid is fed into a stream of liquid ammonia and the liquid mixture in the hydrogenation reactor is driven. Process according to claim 1 for the preparation of meta-xylylenediamine by hydrogenation of isophthalonitrile. Process according to claims 1 or 2, characterized that the mixing device at the place of phthalonitrile in the Stream of liquid Ammonia to a temperature in the range of 1 to 40 ° C above the melting point of the phthalonitrile used is heated. Method according to one of the preceding claims, characterized characterized in that by means of a mixing nozzle as mixing means the liquid phthalonitrile into the stream of liquid Injected ammonia becomes. Method according to one of the preceding claims, characterized characterized in that a part of the reactor discharge as a liquid circulating stream is continuously fed back to the reactor inlet (circulation mode) and the liquid Mixture of ammonia and phthalonitrile in the recycle stream around the Hydrogenation reactor is fed, wherein the recycle stream to greater than 93 wt .-% from liquid Ammonia and xylylenediamine exists. Method according to one of the preceding claims, characterized characterized in that the reactor mixture no further solvent for phthalonitrile contains. Method according to one of the preceding claims, characterized characterized in that the phthalonitrile conversion in the hydrogenation reactor with a single pass greater than 99% is. Method according to one of claims 1 to 6, characterized that the phthalonitrile conversion in the hydrogenation reactor with a simple Passage greater than 99.5 is. Method according to one of claims 5 to 8, characterized that the recycle stream to greater than 94 wt .-% from liquid Ammonia and xylylenediamine exists. Method according to one of claims 5 to 9, characterized that the recycle stream in the range of 25 to 90 wt .-% liquid ammonia. Method according to one of claims 5 to 10, characterized that part of the liquid Reaktoraustrags, as a recycle stream continuously to the reactor inlet is attributed 20 to 95 wt .-% of the total liquid Make reactor output. Method according to one of claims 5 to 11, characterized that the weight ratio from phthalonitrile / ammonia feed stream to recycle stream in the range from 0.05 to 5 lies. Method according to one of the preceding claims, characterized characterized in that the hydrogenation is at a temperature in the range from 40 to 150 ° C carried out becomes. Method according to one of the preceding claims, characterized characterized in that the hydrogenation at an absolute pressure in the range carried out from 100 to 300 bar becomes. Method according to one of the preceding claims, characterized in that the hydrogenation is carried out on a catalyst Ni, Co and / or Fe, as a full catalyst or on an inert support. Method according to one of the preceding claims, characterized characterized in that the hydrogenation on a manganese-doped cobalt full catalyst carried out becomes. Method according to one of the preceding claims, characterized in that the catalyst is used in a tubular reactor or tube bundle reactor as Fixed bed is arranged. Method according to the preceding claim, characterized characterized in that the reactor is operated in trickle mode. Method according to one of the preceding claims, characterized characterized in that the reactor is operated adiabatically. Method according to one of claims 5 to 19, characterized that the circulation stream in a cooler Heat deprived becomes. Method according to one of the preceding claims, characterized characterized in that after the hydrogenation, a purification of xylylenediamine by distilling off the ammonia and optionally lower-boiling By-products over Head and distillative removal of heavy-boiling impurities via bottom he follows. Method according to the preceding claim, characterized characterized in that the xylylenediamine after distillation for further purification with an organic solvent is extracted. Method according to the preceding claim, characterized characterized in that for the extraction cyclohexane or methylcyclohexane used.