N methylaniline

In order to monitor the volatile intermediates and by-products (mainly, the most concerning aromatic amines), the samples were injected in a Shimadzu GC-2010 gas chromatograph provided with flame ionization detector (FID) and split injection mode; 5.0 mL of sample were analyzed in this case. Three successive extractions were conducted with 3.0 mL portions of ethyl acetate (Panreac, 99.5%); the sample was concentrated in a Heidolph rotaevaporator at 40°C up to 2.0 mL, and then measured. Separations were made under a temperature program by using an PTA-5 Fused Silica capillary column (30 m × 0.53 mm × 1.5 μm from SUPELCO). The GC conditions of separation were: Detector and injector temperature: 220°C, carrier gas He, make up gas N₂ (40 mL/min), oven temperature program: 130–150°C under a ramp of 1.0°C/min, then 150–180°C under a ramp of 10°C/min, and finally 1 min at 180°C. Following standards were used to calculate response factors: Phenylamine (Mallinckrodt, 99.99%), N-methylaniline (Sigma-Aldrich, ≥99%), N,N-dimethylaniline (Sigma-Aldrich, 99.57%), N,N-dimethyl-p-phenylenediamine (Alfa Aesar, 96%), 3-Dimethylaminophenol (Alfa Aesar, 97%).

Anhydrous dichloromethane (DCM, spectroscopic grade ≥ 99.8%), aniline (99.5%), N-methylaniline (98%), N,N-dimethylaniline (99%), benzylamine (99%), and toluene (anhydrous, 99.8%) were purchased from Sigma-Aldrich and used without further purification.

The cobalt ferrite and nickel ferrite catalyst supports were synthetized from the following precursors: cobalt(II) nitrate hexahydrate, Co(NO₃)₂∙6H₂O, MW: 291.03 g/mol (Sigma-Aldrich, Saint Louis, MO 63103, USA); nickel(II) nitrate hexahydrate, Ni(NO₃)₂∙6H₂O, MW: 290.79 g/mol (Thermo Fisher GmbH, D-76870 Kandel, Germany); iron(III) nitrate nonahydrate, Fe(NO₃)₃∙9H₂O (VWR International, Leuven, Belgium); ethylene glycol, HOCH₂CH₂OH, (VWR Int. Ltd., F-94126 Fontenay-sous-Bois, France); monoethanolamine, NH₂CH₂CH₂OH (Merck KGaA, D-64271 Darmstadt, Germany); and sodium acetate, CH₃COONa (ThermoFisher GmbH, D-76870 Kandel, Germany). Palladium(II) nitrate dihydrate, Pd(NO₃)₂·2H₂O (Alfa Aesar Ltd., Ward Hill, MA 01835, USA) was used to deposit Pd onto the ferrite catalyst supports. Nitrogen (purity 4.0, Messer) and hydrogen (purity 4.0, Messer) were used during the experiments. Nitrobenzene (NB, Acros Organics, Morris Plains, NJ 07950, USA) was used as reactant during the catalytic hydrogenation tests. The analytical standards applied (azobenzene, nitrosobenzene, N-methylaniline) were purchased from Sigma-Aldrich Co. (St. Louis, MO 63118, USA).