PROCESS FOR PREPARING ANILINE OR AN ANILINE DERIVATIVE

Abstract

The present invention relates to a process for preparing aniline or an aniline derivative, comprising the steps of (I) providing aminobenzoic acid, (II) decarboxylating the aminobenzoic acid to aniline in the presence of an inorganic heterogeneous metal oxide catalyst containing, in relation to the total mass of metal oxides, a mass fraction of Al.sub.2O.sub.3 of 40.0% to 100%, preferably 50.0% to 100%, particularly preferably 60.0% to 100%, the mass fraction of Al.sub.2O.sub.3, in relation to the total mass of the inorganic heterogeneous metal oxide catalyst, being 25% to 100%, and (III) optionally reacting the aniline to form an aniline derivative.

Claims

1. A process for preparing aniline or an aniline conversion product, comprising: (I) providing aminobenzoic acid; (II) decarboxylating the aminobenzoic acid to aniline in the presence of an inorganic heterogeneous metal oxide catalyst containing a proportion by mass of Al.sub.2O.sub.3, based on the total mass of metal oxide, of 40.0% to 100%, and a proportion by mass of Al.sub.2O.sub.3, based on the total mass of the inorganic heterogeneous metal oxide catalyst, of 25% to 100%; and (III) optionally converting the aniline to an aniline conversion product.

2. The process as claimed in claim 1, in which the inorganic heterogeneous metal oxide catalyst contains MgO in a proportion by mass, based on the total mass of metal oxide, of 1.0% to 60.0%.

3. The process as claimed in claim 1, in which the inorganic heterogeneous metal oxide catalyst contains SiO.sub.2 in a proportion by mass, based on the total mass of the inorganic heterogeneous metal oxide catalyst of 1.0% to 30.0%.

4. The process as claimed in claim 1, in which the Al.sub.2O.sub.3 comprises ?-Al.sub.2O.sub.3 or ?-Al.sub.2O.sub.3.

5. The process as claimed in claim 1, in which the decarboxylation of the aminobenzoic acid is performed at a temperature of 150? C. to 300? C.

6. The process as claimed in claim 5, in which the decarboxylation of the aminobenzoic acid is performed at an absolute pressure of 0.05 bar to 300 bar.

7. The process as claimed in claim 1, in which the decarboxylation of the aminobenzoic acid is performed in the presence of aniline.

8. The process as claimed in claim 7, in which the decarboxylation of the aminobenzoic acid is performed batchwise and a proportion by mass of aniline, based on the total mass of aniline and aminobenzoic acid, of 0.1% to 90% is established before the start of the decarboxylation.

9. The process as claimed in claim 7, in which the decarboxylation of the aminobenzoic acid is performed continuously and a proportion by mass of aniline, based on the total mass of aniline and aminobenzoic acid, of 0.1% to 90% is always established during the decarboxylation.

10. The process as claimed in claim 1, in which the decarboxylation of the aminobenzoic acid is performed in the liquid or gas phase in a reactor with an integrated fixed bed of the inorganic heterogeneous metal oxide catalyst, in the liquid or gas phase in a fluidized bed reactor or in the liquid phase in a stirred tank with a suspension of the inorganic heterogeneous metal oxide catalyst contained therein.

11. The process as claimed in claim 10, in which the decarboxylation of the aminobenzoic acid is performed in the liquid or gas phase in a reactor with an integrated fixed bed of the inorganic heterogeneous metal oxide catalyst containing a bed of the catalyst as shaped bodies or a configuration of the catalyst as a monolithic structure, the inorganic heterogeneous metal oxide catalyst being regenerated and reused after decarboxylation.

12. The process as claimed in claim 1, in which step (I) comprises fermenting a raw material containing a fermentable carbon-containing compound and a nitrogen-containing compound in the presence of microorganisms.

13. The process as claimed in claim 12, in which the microorganisms comprise Escherichia coli, Pseudomonas putida, Corynebacterium glutamicum, Ashbya gossypii, Pichia pastoris, Hansenula polymorpha, Yarrowia lipolytica, Zygosaccharomyces bailii or Saccharomyces cerevisiae.

14. The process as claimed in claim 1, in which step (III) is performed and comprises: (1) acid-catalyzed reaction of the aniline with formaldehyde to form di- and polyamines of the diphenylmethane series; (2) acid-catalyzed reaction of the aniline with formaldehyde to form di- and polyamines of the diphenylmethane series, followed by reaction thereof with phosgene to form di- and polyisocyanates of the diphenylmethane series; or (3) conversion of the aniline to an azo compound.

15. The process as claimed in claim 1, in which the aminobenzoic acid provided in step (A) comprises ortho-aminobenzoic acid.

Description

EXAMPLES

Compounds Used:

Reactants:

[0074] Anthranilic acid (AA, petrochemical): C.sub.7H.sub.7NO.sub.2, purity ?98%, Acros Organics [0075] Anthranilic acid (AA, biogenic): C.sub.7H.sub.7NO.sub.2, purity: 98%, Covestro Deutschland AG [0076] Aniline (ANL): C.sub.6H.sub.7N, purity ?99.5%, Sigma-Aldrich [0077] 2-Aminobenzanilide (AMD): C.sub.13H.sub.12N.sub.2O, purity 95%, abcr GmbH [0078] Demineralized water: deionized

Catalysts:

[0079] TiO.sub.2 (Anatas, ST61120), Saint-Gobain [0080] SiO.sub.2 (SS61138), Saint-Gobain [0081] Mesostructured SiO.sub.2 (MCM-41, ?1000 m.sup.2/g BET-SA, Sigma-Aldrich) [0082] ZrO.sub.2 (tetragonal, SZ61152), Saint-Gobain [0083] W-doped ZrO.sub.2 (SZ61143), Saint-Gobain [0084] ZnO (?99%), Sigma-Aldrich [0085] Pural Zn44 (44% Zn in Al.sub.2O.sub.3), Sasol [0086] MgO (purity ?98%), Acros Organics [0087] Pural MG5 (mixed oxide, MgO:Al.sub.2O.sub.3 mass ratio of 5:95), Sasol [0088] Pural MG20 (MgO:Al.sub.2O.sub.3 mass ratio of 20:80), Sasol [0089] Pural MG30 (spinel-type structure, MgO:Al.sub.2O.sub.3 mass ratio of 30:70), Sasol [0090] Al.sub.2O.sub.3 (AI 4126 E), BASF [0091] ?-Al.sub.2O.sub.3(SA6175), Saint-Gobain [0092] Silylated ?-Al.sub.2O.sub.3(SA6175), Saint-Gobain [0093] Pural TH100-AlO(OH), Sasol [0094] ?-Al.sub.2O.sub.3(Eta-Alox V1900) [0095] Siralox 5 (SiO.sub.2:Al.sub.2O.sub.3 mass ratio of 5:95), Sasol [0096] Siralox10 (SiO.sub.2:Al.sub.2O.sub.3 mass ratio of 10:90), Sasol [0097] Siralox30 (SiO.sub.2:Al.sub.2O.sub.3 mass ratio of 30:70), Sasol [0098] Zeolite CBV600 (Na.sub.2O.Math.Al.sub.2O.sub.3.Math.SiO.sub.2, SiO.sub.2/Al.sub.2O.sub.3 mass ratio=5.2; containing 0.2% by mass of Na.sub.2O), Zeolyst International. [0099] Puralox SCFa-160/Ce20, 160 m.sup.2/g BET-SA, Sasol [0100] Puralox SCFa-190/Zr20, 190 m.sup.2/g BET-SA, Sasol [0101] Puralox TH100-150/Ti10, 150 m.sup.2/g BET-SA, Sasol [0102] Puralox TH100/150/L4, 150 m.sup.2/g BET-SA, Sasol

Catalyst Preparation:

[0103] All catalysts for reactions under slurry conditions were sieved (45-90 ?m) and dried for 3 h at 10 mbar and 200? C. before they were used. The catalysts were then stored under an Ar atmosphere until they were used.

Method Description:

[0104] HPLC: For HPLC analysis, a setup from Agilent with UV detection (DAD, measured at 254 nm) was used. For separation, a column from Agilent (Eclipse XDB-C18; 5 ?m; 4.6?150 mm) was used. The flow agent used was a mixture of MeOH and buffer (MeOH:buffer volume ratio=40:60, buffer: 0.7 ml of 85% p.a. H.sub.3PO.sub.4 is diluted to a final volume of 1 I with HPLC water, where the pH of 3.0 is to be set with aqueous sodium hydroxide solution before final filling). The flow rate was 0.7 ml/min. The temperature of the column oven was adjusted to 40? C. The injection volume was 1 ?l. The retention times of the individual components aniline (ANL), anthranilic acid (AA) and 2-aminobenzanilide (ABD) were: ANL=3.2 min; AA=5.2 min; amide=15.7 min.

[0105] The peak areas are converted to area percent (A %). The quantification of the individual components in percent by mass (wt. %), based on the reaction mixture, was enabled by calibration with pure substances beforehand. In addition to the mass composition, the values are used to determine the conversion of anthranilic acid, the yield of aniline formed, the selectivity of the aniline formation and the selectivity for the formation of 2-aminobenzanilide.

General Procedure 1: Decarboxylation of Anthranilic Acid (Slurry; Ex. 1 to 62)

[0106] The decarboxylation of anthranilic acid is performed in a steel reactor charged with 1.6 g of anthranilic acid, aniline (optional, see Table 1 for amount), pulverulent catalyst (optional, see Table 2 for amount) and demineralized water (optional, see Table 1 for amount). The steel reactor is then closed and purged with Ar. The reaction mixture is then stirred for a defined reaction time at a defined temperature and 360 rpm. This increasingly builds up pressure due to the release of CO.sub.2. Subsequently, the reaction mixture is cooled in an ice bath, the pressure is released and the mixture is diluted with 4.0 g of methanol. The diluted mixture is filtered and characterized by means of HPLC analysis.

General Procedure 2: Decarboxylation of Anthranilic Acid (Extrudates; Ex. 63 to 74)

[0107] To decarboxylate anthranilic acid with extrudates, Al.sub.2O.sub.3 extrudates (BASF; AI 4126 E) in cylindrical form (cross section diameter=3 mm, length?4.5 mm) are used and the recyclability over 6 catalyst recycling cycles is investigated. For this purpose, 1.6 g of anthranilic acid is added into an autoclave with a stainless steel cage containing 0.2 g of Al.sub.2O.sub.3 extrudates. 0.25 g of distilled water (13.5% by weight) is then added. After reducing the pressure to 100 mbar and purging the reactor with Ar gas, the reaction mixture is heated to 225? C. and stirred for 1 h (360 rpm). This increasingly builds up pressure due to the release of CO.sub.2. Subsequently, the reaction mixture is cooled in an ice bath, the pressure is released and the mixture is diluted with approx. 4.0 g of methanol. The diluted mixture is characterized by means of HPLC analysis. The used extrudates are then used for the next reaction cycle.

[0108] The experiments are summarized in the tables below. The following abbreviations are used therein: [0109] C=Comparative example [0110] Cat.=Catalyst [0111] ANL=Aniline [0112] AA=Anthranilic acid [0113] AMD=2-Aminobenzanilide

TABLE-US-00001 TABLE 1 Metal oxide compositions of the tested catalysts Catalyst Al.sub.2O.sub.3 MgO SiO.sub.2 TiO.sub.2 ZnO ZrO.sub.2 CeO.sub.2 La.sub.2O.sub.3 Proportion by mass in %, based on the total mass of all metal No. Name oxides present in the material K1 TiO.sub.2 (Anatas) 0 0 0 100 0 0 0 0 K2 SiO.sub.2 0 0 100 0 0 0 0 0 K3 MCM41/SiO.sub.2 0 0 100 0 0 0 0 0 K4 ZrO.sub.2 0 0 0 0 0 100 0 0 K5 W-doped ZrO.sub.2 0 0 0 0 0 ?90 0 0 K6 ZnO 0 0 0 0 100 0 0 0 K7 MgO 0 100 0 0 0 0 0 0 K8 Zeolite CBV 600 24.6 0 75.4 0 0 0 0 0 K9 ?-Al.sub.2O.sub.3 100 0 0 0 0 0 0 0 K10 ?-Al.sub.2O.sub.3 100 0 0 0 0 0 0 0 K11 ?-Al.sub.2O.sub.3; silylated 100 0 0 0 0 0 0 0 K12 Al.sub.2O.sub.3 (BASF, Al 100 0 0 0 0 0 0 0 4126 E) K13 TH100-AIO(OH) 100 0 0 0 0 0 0 0 (boehmite) K14 Pural? ZN44 56 0 0 0 44 0 0 0 K15 Pural? MG5 95 5 0 0 0 0 0 0 K16 Pural? MG20 80 20 0 0 0 0 0 0 K17 Pural? MG30 70 30 0 0 0 0 0 0 K19 Siralox? 5 95 0 5 0 0 0 0 0 K20 Siralox? 10 90 0 10 0 0 0 0 0 K21 Siralox? 30 70 0 30 0 0 0 0 0 K22 Puralox? SCFa- 79.7 0 0 0 0 0 20.3 0 160/Ce20 K23 Puralox? SCFa- 79.6 0 0 0 0 20.4 0 0 190/Zr20 K24 Puralox?TH100- 89.6 0 0 10.4 0 0 0 0 150/Ti10 K25 Puralox? 96.0 0 0 0 0 0 0 4.0 TH100/150/L4

TABLE-US-00002 TABLE 2 Decarboxylation of anthranilic acid to aniline. Reaction temperature T = 185? C.; reaction time t.sub.R = 20 min. Varying catalysts. AA.sub.t=t0 ANL.sub.t=t0 H.sub.2O ANL.sub.t=tR AA.sub.t=tR AMD.sub.t=tR A.sub.ANL X.sub.AA S.sub.ANL S.sub.AMD Ex. Cat. [a] [b] [b] [b] [c] [c] [c] [d] [e] [f] [f] 1 (C) 0 50.0 50.0 0 57.5 41.7 0.8 17.1 19.0 90.0 5.0 2 (C) K1 5.9 50.0 50.0 0 58.1 41.0 0.9 18.2 20.4 89.4 5.3 3 (C) K2 5.9 50.0 50.0 0 59.4 39.6 1.0 21.3 23.7 89.7 5.1 4 (C) K3 5.9 50.0 50.0 0 61.4 37.5 1.1 25.3 28.0 90.4 4.8 5 (C) K4 5.9 50.0 50.0 0 59.8 39.3 0.8 21.8 23.9 91.4 4.3 6 (C) K5 5.9 50.0 50.0 0 65.1 34.1 0.8 32.9 34.9 94.1 3.0 7 (C) K6 5.9 50.0 50.0 0 67.2 32.3 0.4 38.1 39.2 97.2 1.4 8 (C) K7 5.9 50.0 50.0 0 70.3 29.2 0.6 44.4 45.8 97.1 1.5 9 (C) K8 5.9 50.0 50.0 0 71.2 28.1 0.7 46.2 47.8 96.6 1.7 10 K9 5.9 50.0 50.0 0 94.7 5.0 0.3 90.8 91.5 99.2 0.4 11 K10 5.9 50.0 50.0 0 94.3 5.2 0.5 90.0 91.1 98.8 0.6 12 K11 5.9 50.0 50.0 0 95.5 4.1 0.4 92.1 93.0 99.1 0.5 13 K12 5.9 50.0 50.0 0 88.4 11.1 0.5 79.5 80.5 98.6 0.7 13a K12 5.9 50.0 50.0 0 92.5 7.2 0.3 86.8 87.5 99.2 0.4 [g] 14 K13 5.9 50.0 50.0 0 89.0 10.4 0.6 80.5 81.9 98.3 0.9 15 K14 5.9 50.0 50.0 0 73.7 25.8 0.6 51.2 52.6 97.4 1.3 16 K15 5.9 50.0 50.0 0 95.6 4.2 0.1 92.5 92.8 99.7 0.2 17 K16 5.9 50.0 50.0 0 96.8 3.1 0.1 94.6 95.0 99.8 0.1 18 K17 5.9 50.0 50.0 0 96.5 3.4 0.1 94.0 94.2 99.7 0.1 18a K17 5.9 50.0 50.0 0 97.0 2.9 0.1 94.9 95.1 99.8 0.1 [g] 20 K19 5.9 50.0 50.0 0 95.7 4.0 0.3 92.5 93.1 99.4 0.3 21 K20 5.9 50.0 50.0 0 95.4 4.3 0.3 92.0 92.7 99.3 0.4 22 K21 5.9 50.0 50.0 0 77.8 21.4 0.9 59.3 61.3 96.8 1.6 23 K22 5.9 50.0 50.0 0 82.6 16.9 0.6 68.7 70.0 98.1 1.0 24 K23 5.9 50.0 50.0 0 74.0 25.3 0.7 51.6 53.3 96.8 1.6 25 K24 5.9 50.0 50.0 0 76.2 23.2 0.6 56.4 57.9 97.5 1.3 26 K25 5.9 50.0 50.0 0 74.5 24.9 0.6 52.9 54.3 97.4 1.3

TABLE-US-00003 TABLE 3 Decarboxylation of anthranilic acid to aniline. Reaction temperature T = 185? C. Varying reactant mixture compositions. AA.sub.t=t0 ANL.sub.t=t0 H.sub.2O t.sub.R/ ANL.sub.t=tR AA.sub.t=tR AMD.sub.t=tR A.sub.ANL X.sub.AA S.sub.ANL S.sub.AMD Ex. Cat. [a] [b] [b] [b] min [c] [c] [c] [d] [e] [f] [f] 27 0 50.0 50.0 0 60 75.2 22.8 1.9 53.9 58.5 92.2 3.9 28 K17 5.9 50.0 50.0 0 60 98.4 1.5 0.1 97.2 97.4 99.7 0.1 29 0 60.0 40.0 0 60 75.0 23.0 2.2 61.8 66.0 94.0 3.1 (C) 30 K17 6.9 60.0 40.0 0 60 98.2 1.7 0.1 97.5 97.7 99.7 0.1 31 0 72.0 28.0 0 60 72.8 24.7 2.5 67.7 71.4 94.8 2.6 (C) 32 K17 8.3 72.0 28.0 0 60 97.1 2.7 0.2 96.9 97.1 99.7 0.1 33 0 88.0 12.0 0 60 70.4 26.9 2.7 72.9 76.0 95.9 2.1 (C) 34 K17 10 88.0 12.0 0 60 91.0 8.6 0.4 92.5 92.9 99.5 0.2 35 0 100 0 0 60 70.0 27.1 3.0 77.0 80.0 96.4 1.8 (C) 36 K17 11 100 0 0 60 85.2 14.0 0.8 89.3 90.0 99.2 0.4 37 K12 20 100 0 0 180 98.1 1.0 0.9 98.5 99.3 99.2 0.4 38 K12 5.9 100 0 0 180 97.2 0.6 2.2 97.6 99.6 98.0 1.0

TABLE-US-00004 TABLE 4 Decarboxylation of anthranilic acid to aniline. Reaction temperature T = 185? C.; reaction time t.sub.R = 20 min. Varying water contents. AA.sub.t=t0 ANL.sub.t=t0 H.sub.2O ANL.sub.t=tR AA.sub.t=tR AMD.sub.t=tR A.sub.ANL X.sub.AA S.sub.ANL S.sub.AMD Ex. Cat. [a] [b] [b] [b] [c] [c] [c] [d] [e] [f] [f] 39 (C) 0 48.0 48.0 5.0 58.6 40.7 0.7 18.9 20.7 91.2 4.4 40 (C) 0 45.0 45.0 10.0 61.1 38.3 0.6 25.1 26.5 94.6 2.7 41 (C) 0 43.0 43.0 13.0 63.4 36.2 0.4 30.1 31.1 96.6 1.7 42 K12 5.6 48.0 48.0 5.0 94.5 5.3 0.2 90.5 90.9 99.5 0.2 43 K12 5.4 45.0 45.0 10.0 94.0 5.9 0.1 89.5 89.8 99.6 0.2 44 K12 5.2 43.0 43.0 13.0 94.8 5.1 0.1 90.9 91.2 99.7 0.1 45 K10 5.6 48.0 48.0 5.0 94.5 5.4 0.1 90.4 90.7 99.7 0.2 46 K10 5.4 45.0 45.0 10.0 95.3 4.7 0.1 91.8 92.0 99.8 0.1 47 K10 5.2 43.0 43.0 13.0 95.6 4.3 0.1 92.5 92.7 99.8 0.1 48 K17 5.6 48.0 48.0 5.0 96.7 3.2 0.05 94.4 94.6 99.9 0.06 49 K17 5.4 45.0 45.0 10.0 96.0 4.0 0.04 93.1 93.2 99.9 0.05 50 K17 5.2 43 43 13 93.6 6.4 0.02 89.0 89.1 99.9 0.03

TABLE-US-00005 TABLE 5 Decarboxylation of anthranilic acid to aniline. Varying water contents, reaction temperatures and times, and different anthranilic acid sources with K17 and K12. AA.sub.t=t0 ANL.sub.t=t0 H.sub.2O T/ t.sub.R/ ANL.sub.t=tR AA.sub.t=tR AMD.sub.t=tR A.sub.ANL X.sub.AA S.sub.ANL S.sub.AMD Ex. Cat. [a] [b] [b] [b] ? C. min [c] [c] [c] [d] [e] [f] [f] 51 K17 5.9 50 50 0 185 60 98.9 1.0 0.1 98.1 98.3 99.8 0.1 52 K17 5.6 48 48 5.0 185 60 98.9 1.1 0.04 98.1 98.2 99.9 0.05 53 K17 5.9 50 50 0 200 20 98.7 1.2 0.1 97.8 97.9 99.8 0.1 54 K17 5.9 50 50 0 200 60 99.1 0.8 0.1 98.4 98.7 99.8 0.1 55 K17 5.6 48 48 5.0 200 60 99.3 0.6 0.1 98.8 98.9 99.9 0.06 56 K17 5.9 50 50 0 225 20 98.7 1.2 0.1 97.8 98.0 99.8 0.1 57 K17 5.9 50 50 0 225 60 99.2 0.7 0.1 98.6 98.9 99.7 0.1 57a K17 5.9 50 [g] 50 0 225 60 97.9 1.9 0.2 96.4 96.8 99.6 0.2 58 K17 5.6 48 48 5.0 225 60 99.2 0.7 0.1 98.6 98.8 99.8 0.1 59 K17 5.9 50 50 0 230 20 98.8 1.1 0.1 98.0 98.2 99.8 0.1 60 K17 5.9 50 50 0 230 60 99.2 0.7 0.1 98.6 98.9 99.7 0.1 61 K17 5.6 48 48 5.0 230 60 99.0 0.9 0.1 98.4 98.5 99.8 0.1 62 K12 9.7 86.5 0 13.5 225 60 99.5 0.2 0.3 99.6 99.9 99.7 0.1 62a K12 9.7 86.5 [g] 0 13.5 225 60 98.9 0.6 0.5 99.2 99.6 99.5 0.2

TABLE-US-00006 TABLE 6 Decarboxylation of anthranilic acid to aniline without dilution with ANL. Use of the catalyst as extrudate and reuse thereof. AA.sub.t=t0 ANL.sub.t=t0 H.sub.2O T/ t.sub.R/ ANL.sub.t=tR AA.sub.t=tR AMD.sub.t=tR A.sub.ANL X.sub.AA S.sub.ANL S.sub.AMD Ex. Cat. [h] [b] [b] [b] ? C. min [c] [c] [c] [d] [e] [f] [f] 63 K12 9.7 86.5 0 13.5 225 60 98.3 0.5 1.2 98.6 99.6 98.9 0.5 64 K12 9.7 86.5 0 13.5 225 60 98.2 0.7 1.1 98.6 99.5 99.0 0.5 65 K12 9.7 86.5 0 13.5 225 60 98.8 0.1 1.1 98.9 99.9 99.1 0.5 66 K12 9.7 86.5 0 13.5 225 60 98.7 0.4 0.9 98.9 99.7 99.2 0.4 67 K12 9.7 86.5 0 13.5 225 60 98.7 0.4 0.9 98.9 99.7 99.2 0.4 68 K12 9.7 86.5 0 13.5 225 60 99.0 0.2 0.7 99.2 99.8 99.4 0.3 69 K12 9.7 86.5 0 13.5 225 60 99.0 0.1 0.9 99.1 99.9 99.2 0.4 70 K12 9.7 86.5 0 13.5 225 60 98.8 0.3 0.9 99.0 99.8 99.2 0.4 71 K12 9.7 86.5 0 13.5 225 60 98.7 0.5 0.9 98.9 99.7 99.2 0.4 72 K12 9.7 86.5 0 13.5 225 60 98.9 0.3 0.8 99.1 99.8 99.3 0.3 73 K12 9.7 86.5 0 13.5 225 60 98.6 0.4 1.0 98.9 99.7 99.1 0.4 74 K12 9.7 86.5 0 13.5 225 60 99.1 0.3 0.6 99.2 99.8 99.5 0.3

Explanatory Notes for the Tables:

[0114] [a] Proportion by mass in % based on the sum total of AA, ANL, H.sub.2O and cat.; catalyst is used as a powder (slurry); [0115] [b] Proportion by mass in % in the reactant mixture, based on the total mass of AA, ANL and H.sub.2O; [0116] [c] Proportion by mass in % in the product mixture, based on the total mass of AA, ANL and 2-aminobenzanilide; [0117] [d] Chemical yield of aniline in %; [0118] [e] Chemical conversion of anthranilic acid in %; [0119] [f] Selectivity for aniline or 2-aminobenzanilide in %; [0120] [g] Fermentatively prepared anthranilic acid; [0121] [h] Proportion by mass in % based on the sum total of AA, ANL, H.sub.2O and cat.; catalyst is used as an extrudate. In each of Examples 63 to 74, the catalyst from the preceding example was reused. Example 74 therefore represents the twelfth use cycle in the context of catalyst recycling over multiple experiments.

[0122] As shown by the examples, the process according to the invention enables the conversion of aminobenzoic acid with high conversions and low by-product formation, leading to a high yield of aniline. The catalysts according to the invention enable the formation of aniline in very high yields with a variable composition of the ANL/AA substrate mixture, the water content and a variable process window in relation to the reaction time and temperature. The technical effect in relation to increased aniline yield with the catalysts according to the invention with respect to the prior art was shown. It is possible to use the catalyst as a slurry or extruded solid. Long-term stability of the catalyst was demonstrated without any noticeable drop in the aniline yield over 12 cycles. The catalysts according to the invention are suitable for decarboxylating petrochemically prepared anthranilic acid and biogenically based anthranilic acid.