Catalyst for the alkylation of aromatic amines

Abstract: A catalyst suitable for use in the alkylation of aromatic amines which comprises attapulgite together with iron oxide and one or more transition metal oxides.

Description: The present invention relates to a catalyst and a process for the preparation of the said catalyst useful for the preparation of alkylated aromatic amines. This invention particularly relates to a process for preparation of attapulgite impregnated with a combination of iron oxide and oxides selected from transition metals of the periodic table. Attapulgite used in the catalyst is fibrous clay. The chemical analysis of attapulgite clay shows the presence of oxides such as SiO 2 , Al 2 O 3 , MgO, Na 2 O, Fe 2 O 3 and water along with traces of nickel, chromium, zinc, copper, lead, tin, vanadium and silver and the composition of Attalpulgite in form of mole percent is as follows: SiO 2 55.03% Al 2 O 3 10.24% Fe 2 O 3 03.53% MgO 10.49% K 2 O 00.47% H 2 O - 09.73% H 2 O + 10.13% BACKGROUND OF THE INVENTION: Attapulgite is used as a polymerisation catalyst, in refining vegetable oils and fats, as a carrier for granular and powdered agricultural chemicals (insecticides and herbicides), in petroleum refining, decolourising, neutralising, brightening and for desulphurisation. It is also used as an oil base and water base foundry sand binders, latex paint thickener, gelling agent, polishing-suspending agent for abrasives and as a wax emulsion stabilizer. BRIEF DESCRIPTION OF THE INVENTION: We have carried out extensive research in respect of the use of attapulgite for catalysing chemical reactions. We have observed during our research that attapulgite can be used as catalyst for alkylation reaction. On our continued work developing attapulgite as a catalyst for selective alkylation of aromatic amines we have observed that when attapulgite is impregnated with a combination of iron oxide and oxides selected from transition metals of the periodie table, the effect of alkylation is greatly enhanced. The catalysing activity of the resultant catalyst for the alkylation reaction, in particular for ortho and N-alkylation is found to be enhanced. Alkylated aromatic amines arc useful in a broad range of applications. Particularly ortho- alkylated aromatic amines are used as intermediated for producing dyes, resin stabilisers, rubber compounding ingredients and the like. N-Alkylatcd aromatic amines are useful in a broad range of applications. They are used as raw materials for synthesis of organic chemicals, and as intermediates for producing dyes, in agrochemical industries like fertilizers, as resin stabilisers, rubber compounding ingredients and the like. Several combinations of the catalyst have been reported, in particular alumina promoted with different metal oxides appears to have been widely employed. Zeolites have been used extensively as catalysts for the production of N-alkylated anilines. Bauxite is also proved to be a good catalyst for this reaction. In our copending EPO. application No. EP-A-1002789 (agent's ref 33.69288 ) we have described a process for the preparation of alkylated aromatic amines which comprises reacting an aromatic amine such as aniline, toludine, xylidine, N-methyl aniline , N-ethyl aniline, m-ethyl aniline, p-ethyl aniline, o-ethyl aniline with a primary or secondary alcohol such as ethanol, methanol,isopropyl alcohol in the presence of attalpulgite impregnated with combination of iron oxide and oxides selected from transition metals of the periodic table as a catalyst prepared at a temperature in the range of 300-400 °C and recovering the desired amine by conventional methods. Here, we have described a process for the preparation of alkylated aromatic amines employing the catalyst of the present invention. The main object of the present invention is to provide a catalyst and a process for the preparation of the said catalyst consisting of attapulgite impregnated with iron oxide and oxides selected from transition metals of the periodic table. This invention is based on the findings that when attapulgite is impregnated with a combination of iron oxide and oxides selected from transition metals of the periodic table the activity of the resultant catalyst is enhanced for selective alkylation of the aromatic amines. DETAILED DESCRIPTION OF THE INVENTION: Accordingly, the present invention provides a catalyst suitable for use in the alkylation of aromatic amines which comprises attapulgite together with iron oxide and one or more metal oxide selected from transition metal oxides, or oxides of germanium, tin, zinc, magnesium or aluminium. In particular, the present invention provides a catalyst comprising 1-75% of iron oxide, 1-10% of transition metal oxide and the balance being attapulgite useful for the preparation of alkylated aromatic amines and a process for the preparation of the said catalyst useful for the preparation of alkylated aromatic amines. In another embodiment of the present invention, it provides a process for the preparation of the catalyst which comprises impregnating attapulgite with a combination of iron oxide and oxides selected from transition metals of the periodic table, converting the resultant catalyst to the desired form, drying the catalyst and calcining by known methods. The oxides of the transition metals used for impregnation may be selected from copper oxide, titanium oxide, zirconium oxide, chromium oxide and the like. The amount of iron oxide used ranges from 1-75% and the amount of transition metal oxide used may range from 1-10%. The resulting catalyst may be dried at a temperature in the range of 90 to 100° C. The catalys may be calcined at a temperature in the range of 400 to 450° C. The invention is described in detail in the examples which are provided by way of illustration only and should not be construed to limit the scope of the invention. EXAMPLES Example 1: 76 gms of ferric nitrate 9 hydrates is dissolved in 200 ml of distilled water. Attapulgite, 170 gms is taken to which vacuum is applied. Ferric nitrate solution is added to attapulgite with constant stirring. Excess water in the mixture is evaporated. When the mixture is slightly wet 2.0 gms of germanium dioxide is added with constant mixing. The resultant catalyst is then extruded and pelletized. The pellets are dried at a temperature of 90-100°C for a period of 24 hours and then calcined at 450°C for a period of 5 hours. Example 2: 305 gms of ferric nitrate 9 hydrates is dissolved in 200 ml of distilled water. Attapulgite, 80 gms is taken to which vacuum is applied. Ferric nitrate solution is added to attapulgite with constant stirring. Excess water in the mixture is evaporated. When the mixture is slightly wet 4 gms of tin oxide is added with constant mixing. The resultant catalyst is then extruded and pelletized. The pellets are dried at a temperature of 90-100°C for a period of 24 hours and then calcined at 450°C for a period of 5 hours. Example 3: 128 gms of ferric nitrate 9 hydrates is dissolved in 200 ml of distilled water. Attapulgite, 150 gms is taken to which vacuum is applied. Ferric nitrate solution is added to attapulgite with constant stirring. Excess water in the mixture is evaporated. When the mixture is slightly wet 5 gms of zinc oxide is added with constant mixing. The resultant catalyst is then extruded and pelletized. the pellets are dried at a temperature of 90-100°C for a period of 24 hours and then calcined at 450°C for a period of 5 hours. EPA 1002789 (agent's ref 33.69288) mentioned above includes further Examples of catalysts of this invention.

Claims: A catalyst suitable for use in the alkylation of aromatic amines which comprises attapulgite together with iron oxide and one or more metal oxide selected from transition metal oxides, or oxides of germanium, tin, zinc, magnesium or aluminium. A catalyst according to claim 1 in which the transition metal oxide is an oxide of copper, titanium, zirconium, chromium, germanium, tin, zinc, magnesium or aluminium. A catalyst according to claim 1 or claim 2 which contains 1-75% by weight iron oxide and 1-10% by weight transition metal oxide. A process for the preparation of the catalyst according to any preceding claim, which comprises impregnating or intimately mixing attapulgite with the iron oxide and the transition metal oxide, converting the resultant catalyst to the desired form, and drying and calcining the catalyst by known methods. A process according to claim 4, wherein the drying of the catalyst is effected at a temperature in the range of 90 to 100°C. A process according to claim 4 or claim 5, wherein the catalyst is calcined at a temperature in the range of 400 to 450°C.

Inventors: BHALERAO UDAY T, PATWARI AKASH N R, SATYAVATHI BANKUPALLI, BHALERAO, UDAY T., PATWARI, AKASH N.R., SATYAVATHI, BANKUPALLI
Applicants: COUNCIL SCIENT IND RES, COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH
Application year: 1998
Main classification: B01J21
IPC codes: B01J23, B01J21