US-12616960-B2 - Catalyst system for producing aromatic amines

US12616960B2US 12616960 B2US12616960 B2US 12616960B2US-12616960-B2

Abstract

The invention relates to a catalyst system suitable for hydrogenating aromatic nitro compounds (I) to form the corresponding aromatic amines (II), the catalyst system containing, as essential constituents: a component A selected from the group consisting of silicon carbide, corundum (alpha-Al 2 O 3 ) and slightly porous to non-porous zirconium oxide (ZrO 2 ); and a component B, containing B1—a carrier substance selected from the group consisting of silicon dioxide, gamma-, delta- or theta-aluminum oxide Al 2 O 3 , titanium dioxide, zirconium dioxide and graphite, B2—a metal or a plurality of metals selected from the group consisting of copper, nickel, palladium, platinum and cobalt, and optionally B3—an additional metal selected from the group consisting of at least one metal selected from main group I, main group II, main group IV and sub-groups II, V, VI and VIII of the periodic table of the elements, the proportion of component A being in the range of 5 to 60 wt %, in relation to the total weight of the catalyst system, and the aromatic nitro compounds (I) being those of the general formula R—(NO 2 ) n , (I), and the aromatic amines (II) being those of the general formula R—(NH 2 ) n , (II), and the moieties R and indices n in formulas (I) and (II) having the following meaning: R is a substituted or unsubstituted aromatic C 6 -C 10 moiety and n is an integer from 1 to 5.

Inventors

Veronika Wloka
Dominik GARELLA
Michael Reiser
Thomas Heidemann
Hendrik De Winne

Assignees

BASF SE

Dates

Publication Date: 20260505
Application Date: 20200401
Priority Date: 20190412

Claims (6)

1 . A catalyst system suitable for the hydrogenation of aromatic nitro compounds (I) to the corresponding aromatic amines (II), comprising as essential constituents a component A silicon carbide, wherein component A is a constituent of component B1 and a component B comprising B1 a support material selected from the group consisting of silica, gamma-, delta- or theta-alumina Al 2 O 3 , titanium dioxide, zirconium dioxide, and graphite and B2 copper, wherein a cumulative content of the metals in component B2, calculated in elemental form, based on the total mass of the catalyst system is from 5% to 30%, and optionally B3 a further metal selected from the group consisting of at least one metal selected from main group I, main group II, main group IV, and subgroups II, V, VI, and VIII of the periodic table of the elements, wherein component A is within a range from 15% to 35% by weight based on the total weight of the catalyst system and where the aromatic nitro compounds (I) are those of the general formula R—(NO 2 )n (I), the aromatic amines (II) are those of the general formula R—(NO 2 )n (II), and the radicals R and indices n in formulas (I) and (II) are defined as follows: R is a substituted or unsubstituted aromatic C 6 to C 10 radical and n is an integer from 1 to 5 wherein the support material B1 has an average pore volume in the range from 0.6 ml/g to 1.3 ml/g, measured according to DIN 66133.
2 . A process for producing a catalyst system as defined in claim 1 , by i) producing a support material B1 comprising a component selected from the group consisting of silica, gamma-, delta- or theta-alumina Al 2 O 3 , titanium dioxide, zirconium dioxide, and graphite and contacting this support material with copper, and optionally with B3 selected from the group consisting of at least one metal selected from main group I, main group II, main group IV, and subgroups II, V, VI, and VIII of the periodic table of the elements, and combining this with silicon carbide.
3 . A process for producing aromatic amines (II) through catalytic hydrogenation of the corresponding aromatic nitro compound (II), comprising contacting the aromatic nitro compound with the catalyst system as defined in claim 1 .
4 . The process according to claim 3 , wherein the process is executed in the fluidized bed.
5 . The process according to claim 3 , wherein the aromatic amine compound (II) is aniline and the corresponding aromatic nitro compound (I) is nitrobenzene.
6 . The catalyst system according to claim 1 , having a k value from 445 to 500 W/m 2 K.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national stage application (under 35 U.S.C. § 371) of PCT/EP2020/059228, filed Apr. 1, 2020, which claims benefit of European Application No. 19168919.9, filed Apr. 12, 2019, both of which are incorporated herein by reference in their entirety. The invention relates to a catalyst system and to a process for producing a catalyst system that is suitable for the production of aromatic amines (II), in particular aniline, as defined in the claims, and also to the use of the catalyst system for producing aromatic amines (II), in particular aniline, as defined in the claims, and to a process for producing aromatic amines (II), in particular aniline, using this catalyst system, as defined in the claims. Catalysts suitable for the production of aromatic amines, for example aniline, through hydrogenation of the parent nitro compounds, and processes for the production thereof, are known. CN-A 1 657 162 relates for example to a fluidized-bed catalyst for producing aniline through hydrogenation of nitrobenzene. The catalyst comprises silica (SiO2) as support material and also copper, chromium, molybdenum, and a further metal selected from nickel, zinc, barium, vanadium, bismuth, lead or palladium. The abovementioned metals are present in the catalyst as the oxide in a specific weight ratio. Although the abovementioned metals are already introduced into the process in the form of aqueous salt solutions during production of the silica, the metals are not drawn onto the already-formed support. A process for producing aromatic amines such as aniline through hydrogenation of the corresponding nitroaromatics with hydrogen on immobilized catalysts under adiabatic conditions is described in EP-A 1 882 681. All catalysts that can be used for the gas-phase hydrogenation of nitro compounds are in principle suitable as catalysts. The metal component of the catalysts may be present either in the form of an alloy or as a mixed oxide and the catalyst may optionally be produced using an inert support material. Examples of suitable support materials are alumina (α- and γ-modification), silica (SiO2), titanium dioxide (TiO2), red earth, water glass or graphite. The metals used are preferably Pd, Te, V, Nb, Ta, Cr, Mo, W, Pb or Bi. Preference is given to using α-alumina having a BET surface area of less than 10 m2/g as support material. The reaction of aromatic nitro compounds R—(NO2)n (I) with hydrogen on a catalyst usually leads to the corresponding aromatic amines R—(NH2)n, (II). The radicals R and the indices n are as defined below. In addition to the fixed-bed process, a highly suitable process variant for the hydrogenation of aromatic nitro compounds, for example nitrobenzene, to aromatic amines, for example aniline, on solid catalysts is the so-called fluidized-bed process described for example in Ullmann's Encyclopedia of Industrial Chemistry vol. 15, pp. 319-366 and in particular for the production of aniline in DE 1114820 B. Here the particulate supported catalyst forms a fluidized bed. Process requirements for such a solid catalyst, especially for a fluidized-bed catalyst, include for example good fluidity in order that a stable fluidized bed can be formed, good mechanical stability, and—for both the fixed-bed process and the fluidized-bed process—not least good thermal conductivity of the solid catalyst in order to dissipate the relatively high heat of reaction of the hydrogenation reaction from the solid catalyst to the cooling devices of the reaction vessel, for example heat exchangers. The property profile of catalysts of the prior art suitable for the hydrogenation of aromatic nitro compounds to aromatic amines is still in need of further improvement, particularly as regards heat transfer to a cooling device, for example a heat exchanger. The object of the present invention is to provide a catalyst system, a process for producing this catalyst system that is suitable for the production of aromatic amines (II), in particular aniline, and also the use of the catalyst system for producing aromatic amines (II), in particular aniline, and to provide a process for producing aromatic amines (II), in particular aniline, using this catalyst system. The object is achieved by a catalyst system suitable for the hydrogenation of aromatic nitro compounds (I) to the corresponding aromatic amines (II), comprising as essential constituents a component A selected from the group consisting of silicon carbide, corundum (alpha-Al2O3) and low-porosity to non-porous zirconium oxide (ZrO2) and a component B comprising B1 a support material selected from the group consisting of silica, gamma-, delta- or theta-alumina Al2O3, titanium dioxide, zirconium dioxide, and graphite and B2 one or more metals selected from the group consisting of copper, nickel, palladium, platinum, and cobalt, and optionally B3 a further metal selected from the group consisting of at least one metal selected from