HDN of o-toluidine

Mesoporous alumino silicate molecular sieves with MCM-41 type structure synthesized using various A1 sources (i.e. aluminum sulphate, aluminum isopropoxide, pseudo boehomite and sodium aluminate) have been used as supports for Ni - Mo catalysts. The HDN of o-toluidine tmd cyclohexylamine was studied in a fixed bed flow reactor at 450°C and PH2 = 1 atm. The activity per unit of weight of the MCM - 41 supported catalysts was evaluated and compared to that of supported catalysts preptu ed by sequential impregnation method. The XRD and DRS data have been used to explain the observed trend in catalytic activity towards HDN reaction... 

Influence of fluorination on the kinetics of the HDN of o-toluidine over tungsten sulfide catalysts ex ammonium tetrathiotungstate... 

The kinetics of the hydrodenitrogenation (HDN) of o-toluidine was studied over alumina-supported sulfided timgsten catalysts prepared from tetrathiotungstate. The Langmuir-Hinshelwood kinetic model was used to fit the data. The kinetic parameters were obtained by varying the initial reactant partial pressure and the reaction temperature. Fluorination of alumina increased the HDN rate constant, decreased the adsorption constant of o-toluidine, and increased the activation energies and the preexponential factors. 

The catalysts used in the present study were prepared from anunonium tetrathiotungstate (ATT), containing 10 wt% tungsten. The content of fluorine in the fluorinated catalyst was 1 wt%. Details of the catalyst preparation can be found elsewhere [2]. The HDN reactions were carried out in a continuous-flow microreactor. 0.4 to 1.2 g of the catalyst sample diluted with 8 g SiC was sulfided in situ with a mixture of H2S (10 mol%) and H2 (90 mol%) at 400°C and 1.5 MPa for 4 h. After sulfidation the temperature was cooled to 370°C, the pressure was increased to 3.0 MPa, and the liquid feed was introduced to the reactor by means of a high-pressure pump, with n-octane as the solvent and n-hqjtane as internal standard. Dimethyldisulfide was added to the feed to generate H2S (6 kPa) in the reaction stream. The partial pressure of o-toluidine varied fipom 1 to 9 kPa. 

It can be seen that the HDN conversion of o-toluidine is dependent of the initial partial pressure of o-toluidine. At the same weight time, the feed with a higher initial partial pressure gives a lower conversion because of the self-inhibition effect. This indicates that the reaction order of o-toluidine is between 0 and 1. A similar result was obtained for the F-ffee catalyst (ATT/AI2O3). 

The Langmuir-Hinshelwood model has been applied in the study of the kinetics of the HDN of o-propylaniline, decahydroquinoline, and quinoline over NiMo(P)/Al203 catalysts by Jian and Prins [5-7]. It has been reported that direct C(5p )-N bond cleavage takes place on a different catalytic site than hydrogenation reactions [8]. Nevertheless, Jian and Prins assumed that o-propylaniline has the same adsorption constant on the catalytic sites used in hydrogenation and in C(sp yN bond cleavage [5]. The fact that changes in the initial partial pressure of o-toluidine do not affect the ratio of the product of path 1 to the product... 

To simplify the quinoline network reaction, we studied the HDN of o-propylaniline and o-toluidine, the latter has chemical properties similar to those of o-propylaniline. o-Toluidine has many advantages as a model reactant. Due to its molecular structure, all reactions which take place in an industrial HDN process also occur in the HDN network of o-toluidine these include hydrogenation of the aromatic ring, C-N bond cleavage (be it C(sp2)-N or C(sp )-N bond cleavage), and alkene hydrogenation [5,6]. However, it is too comphcated... 

Nevertheless, even under conditions for which diffusion limitations could be excluded, MCHA was still converted directly to MCH. By adding substantial partial pressures of H2S, it was shown that the formation of MCH resulted from the nucleophilic substitution of MCHA to give 2-methylcyclo-hexylthiol and subsequent fast hydrogenolysis to give MCH. These results mean that the network of the HDN of anilines is quite complex the network of o-methylaniline (o-toluidine) is shown in Scheme 19. 

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