Direct amination of hydrocarbons

Abstract

Process for preparing aminated aromatic hydrocarbons that may be substituted comprising the steps of reacting an aromatic hydrocarbon with ammonia in the presence of a catalyst having a crystalline microporous structure wherein the catalyst comprises vanadium aluminophosphate molecular sieve (VAPO) and/or aluminophosphate molecular sieve (AlPO) and wherein the catalyst is preferably impregnated with nickel and/or copper, and wherein the aromatic hydrocarbon may be substituted.

Claims

1. A process for preparing aminated aromatic hydrocarbons comprising the steps of reacting an aromatic hydrocarbon with ammonia in the presence of a catalyst having a crystalline microporous structure wherein the catalyst comprises vanadium aluminophosphate molecular sieve (VAPO) and wherein the catalyst is impregnated with nickel and copper in amounts such that the nickel content is between 1 wt % and 30 wt % and the copper content is between 1 wt % and 30 wt %, based on the total weight of the catalyst.

2. The process according to claim 1, wherein the catalyst is treated by reduction or calcination.

3. The process according to claim 2, wherein the catalyst is reduced in the presence of molecular hydrogen.

4. The process according to claim 2, wherein the reduction with molecular hydrogen occurs at a temperature between 100 and 300 C.

5. The process according to claims 2, wherein the reduction with molecular hydrogen occurs during between 50 and 100 minutes.

6. The process according to claim 2, wherein the calcination with air occurs at a temperature between 400 and 700 C.

7. The process according to claim 1, wherein the catalyst has a framework type code provided by the International Zeolite Association selected from the group consisting of AFI, AEL, ATO, AEI, AET, AFN, AFO, AFT, ATV, CHA, ERI, LEV, SOD, and VFI.

8. The process according to claim 1, wherein the aromatic hydrocarbon is benzene.

9. The process according to claim 1, wherein the catalysts are treated at a temperature between 350 and 700 C.

10. The process according to claim 1, wherein the amination occurs at a temperature between 400 and 700 C.

11. The process according to claim 1, wherein the amination occurs at a pressure between 50 and 150 bar.

12. The process according to claim 1, wherein the aromatic hydrocarbon is substituted.

Description

EXAMPLES

(1) Reactor Set-Up and Experimental Procedure

(2) A tubular reactor (length=31 cm, inner diameter=0.43 cm) is charged with 600 mg of catalyst in the center of the tube (particle size between 0.2-0.6 mm) and the remained space is filled up with carborundum. The catalyst bed has a length of 6.9 cm. The catalysts have been activated in situ prior to the amination catalytic reaction. The catalyst activation has been performed under air flow (190 ml/min) at 500 C. for 30, 60 or 120 min (examples 1,2,4,6 and 9) or under hydrogen flow (100% H.sub.2, at 60 ml/min) at 450 C. for 90 min (examples 3 and 5) or at 200 C. for 60 or 80 min (examples 7, 8, 10). After that, the reactor is purged with nitrogen during 30 min and the temperature is brought to 450 C. Then ammonia is introduced to the reactor via a syringe pump to reach an internal pressure of 80 bar (10 bar fluctuating during the reaction). After equilibrating the pressure, the reaction is started with a flow of 1.61 ml/h of ammonia (9.2 equiv., Linde 99.98%) and 0.565 ml/h of benzene (1.0 equiv., Aldrich 99.9%) added continuously to the system. The reaction is running 140 or 300 minutes. For each sample the reactor effluent is collected in methanol for 3 min at 2 C. using dodecane as an external GC standard. The sample is then analyzed by gas chromatography (VARIAN CP3800 with FID detector, HP5 column 30 m).

(3) Synthesis of the VAPO Catalysts

(4) The VAPO-5 support is prepared according to the literature (P.Concepcin, J. M. Lpez Nieto, J. Pres-Pariente J. Mol. Catal. A: Chem. 97 (1995) 173). In detail, 13 g of orthophosphoric acid (Aldrich, 85 wt %), 30 g of H.sub.2O miliQ and 6.7 g of pseudoboehmite (CATAPAL 70 wt % Al2O3) was stirred together for 2 h. 7.5 g of triethylamine (Aldrich 99 wt %) was slowly added under stirring and kept for another 2 h under stirring (Solution A). In a separate vessel, 2.5 g of triethylamine, 10 g of H.sub.2O miliQ and 1.2 g of V.sub.2O.sub.5 (Aldrich, 99.6 wt %) was mixed under stirring at 40 C. for 1 h until complete dissolution of the vanadium salt (Solution B). Solution B was slowly added to solution A and kept for another 2 h under stirring. At this point, a homogenous gel is obtained with pH of 5.6. The gel is introduced in 60 ml PTFE-lined stainless steel autoclaves and heated at 200 C. for 16 h. Afterwards, the autoclaves were quenched in cool water, centrifuged at 10,000 rpm, washed and dried at 80 C. The solid is calcined in air at 550 C. for 8 h in air. To reach the calcination temperature, the material is heated up in 2 C./min. The vanadium loading in the prepared VAPO-5 is 0.5 wt %. After this, wet impregnation techniques are applied to introduce the nickel and/or copper on the catalyst. An 7 wt % nickel loading was used in the VAPO-Ni samples (examples 4 and 5 in table 1), in detail, 296 mg (Ni(OAc).sub.2(H.sub.2O).sub.4)(Panreac, 95 wt %) were dissolved in 5 ml water through slightly heating at 40 C. to prepare a salt solution. The solution was dropwise added under stirring on 1 g of VAPO-5 . The final solid was dried at 100 C. for 12 h, followed by air calcination at 500 C./min for 8h with a heating rate of 2 C./min. In the VAPO-Ni,Cu samples (examples 6 to 8 in table 1) 7 wt % nickel and 3.5 wt % copper loading was used. In detail, (296 mg, 1.19 mmol) (Ni(OAc).sub.2(H.sub.2O).sub.4) (Panreac, 95%) and (128 mg, 0.28 mmol) Cu(NO.sub.3).sub.4(H.sub.2O).sub.5 (Aldrich 98%) were dissolved in 1.5 ml water through slightly heating at 40 C. to prepare a salt solution. The salt solution is then further used for impregnation of the VAPO sample. Afterwards the impregnated material is dried over night at 100 C. followed by air calcination at 500 C./min for 8 h with a heating rate of 2 C./min. The subsequent calcination is done in situ in the flow reactor according to the conditions set out in the table with a heating rate of 2 C./min.

(5) Synthesis of the ALPO Catalyst

(6) ALPO-5 was prepared according to the following receipt: 13 g of orthophosphoric acid (Aldrich, 85 wt %), 40 g of H.sub.2O miliQ and 6.7 g of pseudoboehmite (CATAPAL 70 wt % Al.sub.2O.sub.3) was stirred together for 2 h. After that, 10 g of triethylamine (Aldrich 99 wt %) was slowly added under stirring and kept for another 2 h under stirring. The gel is introduced in 60 ml PTFE-lined stainless steel autoclaves and heated for 200 C. for 16 h. After this, the autoclaves were quenched in cool water, centrifuged at 10,000rpm, washed and dried at 80 C. The solid is calcined in air at 550 C. for 8 h in air with a heating rate of 2 C./min. After this, wet impregnation techniques are applied to introduce the nickel and copper on the ALPO-5 sample. The synthetic procedure is the same as described above in the VAPO-5-NiCu samples using instead of VAPO-5, ALPO-5.

Comparative Example 1

(7) The catalyst was prepared by coprecipitation techniques and includes Ni, Cu, Zr, and Mo as metal oxides. The catalyst was synthesized according to example 1 of US 2009/0292144 A1. The amination reaction of benzene occurred in the above described reaction set up. At 350 C. and 80 bar there was no aniline formed. However, by increasing the reaction temperature to 450 C. an average yield of 0.43% was obtained (see example 1 in table 1). The side products that are formed are toluene, benzonitrile, biphenyl and carbazole.

Comparative Examples 2-5

(8) VAPO-5 prepared as described above was used in the reaction set up and procedure as described above.

(9) The amination reaction occurred as described above in the experimental procedure of the patent.

(10) VAPO-5 showed activity of the direct amination of benzene and aniline was formed (see example 2-5 in table 1). The activation of the catalyst in situ in the reactor with air or hydrogen did not change the results.

(11) Also, VAPO-5 impregnated with nickel (prepared as described above) was used to aminate benzene in the reaction set up as describe above. The reaction occurred as described above in the experimental procedure of the patent.

(12) It was found that by introducing nickel in VAPO, the maximum yield did not change but the average yield increased (see example 4 of table 1).

Examples 6-8

According to the Invention

(13) Ni,Cu-VAPO-5 prepared as described above was used in the reaction set up and procedure as described above.

(14) It is found that by impregnation of VAPO-5 with Ni and Cu, the activity of the catalyst increased, especially when the catalyst is reduced with hydrogen at 200 C. Reducing at 200 C. for 60 min, the yield reached was 1% at 140 minutes reaction time (see 7). Increasing the reduction time, from 60 min to 80 min, at the same temperature of 200 C., a maximum yield of 3.3% was formed at 160 minutes reaction time and an average yield of 1% was obtained. In addition, the selectivity of the reaction was very high. Carbazole, benzonitrile, biphenyl, toluene and diphenylamine are observed only in traces during the reaction. The calculation of the selectivity does not include the loss of benzene inside the reactor through coking or simple adsorption.

(15) The catalyst has been regenerated by heating in-situ in air at 500 C. for 2 hours, then reducing in hydrogen at 200 C. for 80 minutes. After each cycle the catalyst was tested again using the procedure outlined above. It has been found that 9 regeneration cycles were completed successfully with no decrease in catalyst performance.

Example 9 and 10

According to the Invention

(16) Common aluminophosphate impregnated with nickel and copper (see above) was used in the reaction set-up. The synthesis procedure and reaction set-up are as described above.

(17) The AlPO material provided almost the same result with both hydrogen and air activation. Also the ALPO catalyst that was impregnated with Ni and Cu showed good results.

(18) TABLE-US-00001 TABLE 1 results of experiments in examples 1-10 treatment of reaction average yield, Sample catalyst WHSV catalyst condition highest yield selectivity 1* Ni, CU, 0.83 h.sup.1 Air at 500 C. 450 C., 80 bar 0.43%, 0.88% 90% Zr, Mo 2** VAPO-5 0.83 h.sup.1 Air at 500 C., 450 C., 80 bar 0.05%, 0.15% 69% 2 h 3** VAPO-5 0.83 h.sup.1 H.sub.2 at 450 C., 450 C., 80 bar 0.06%, 0.15% 63% 1.5 h 4** VAPO- 0.83 h.sup.1 Air at 500 C. 450 C., 80 bar 0.09%, 0.14% 67% Ni 30 min 5** VAPO- 0.83 h.sup.1 H.sub.2 at 450 C. 450 C., 80 bar <0.01%, 0.03% 67% Ni 1.5 h 6 VAPO- 0.83 h.sup.1 Air at 500 C. 450 C., 80 bar 0.06%, 0.11% 56% Ni, Cu 60 min 7 VAPO- 0.83 h.sup.1 H.sub.2 at 200 C. 450 C., 80 bar 0.66%, 1.01% 89% Ni, Cu 60 min 8 VAPO- 0.83 h.sup.1 H.sub.2 at 200 C. 450 C., 80 bar 0.98%, 3.31% 92% Ni, Cu 80 min 9 AlPO- 0.83 h.sup. Air at 500 C. 450 C., 80 bar 0.85%, 1.52% 88% Ni, Cu 60 min 10 AlPO- 0.83 h.sup. H.sub.2 at 200 C. 450 C., 80 bar 0.52%, 1.47% 87% Ni, Cu 80 min *comparative example. Catalyst prepared according to example 1 of US 2009/0292144 A1; **comparative examples; WHSV is the weight hourly space velocity