Kinetic Modeling of Reductive Alkylation of Aniline with Acetone Using Pd/Al₂O₃ Catalyst in a Batch Slurry Reactor

Abstract

The kinetics of reductive alkylation of aniline with acetone was studied in a slurry reactor under isothermal conditions in a temperature range of 378-408 K using 3% Pd/Al 2 O 3 catalyst. Experimental data on concentration-time as well as hydrogen consumption-time profiles were obtained to study the effect of concentration of aniline, catalyst loading, and partial pressure of hydrogen. Separate controlled experiments were performed to understand the nature of the condensation reaction between aniline and acetone, which forms the Shiff's base intermediate. From the concentration-time profiles and the effect of reaction conditions, it was found that the noncatalytic equilibrium formation of the Shiff base intermediate was the slowest step in the multistep reaction sequence. Several rate equations were considered to fit the batch slurry reactor data, and rate models based on competitive dissociative adsorption of hydrogen and the reactive substrates in the rate-limiting catalytic steps were found to represent the experimental data. The kinetic parameters were evaluated by fitting the integral batch reactor data at different temperatures. The activation energies, heat of adsorption, and entropy of adsorption of all the reactant species were also evaluated.

Kinetics of Reductive Alkylation of p-Phenylenediamine with Methyl Ethyl Ketone Using 3% Pt/Al2O3 Catalyst in a Slurry Reactor

“…All the reductive alkylation reactions were carried out in a 3 × 10 -4 m 3 capacity high-pressure stirred autoclave supplied by Parr Instrument Co., Moline, IL, the schematic of which is described elsewhere. 27 The autoclave having a diameter of 6.4 × 10 -2 m (impeller diameter of 4 × 10 -2 m) was equipped with an electrically heated jacket, a turbine agitator, and a variable speed magnetic drive. The temperature and the speed of agitation were controlled by means of a Parr 4842 controller.…”

“…A more detailed kinetic study was reported from our group for reductive alkylation of aniline with acetone (a ketone) using Pd/Al 2 O 3 catalyst, in which the impact of homogeneous and heterogeneous catalyzed reactions on overall reaction kinetics was addressed. 27 In this paper, we are extending our approach to a more complex reaction system with p-phenylenediamine (PPDA, I) as the amine substrate, wherein two amine functionalities are available for the alkylation reaction and, hence, the complexities in the reaction network. A detailed reaction scheme for reductive alkylation of PPDA with methyl ethyl ketone (MEK) is shown in Figure 2.…”

Tailoring supported palladium sulfide catalysts through H2-assisted sulfidation with H2S

“…The main by-products were N-(1,3-dimethylbutyl)-N 0 -cyclohexane-p-phenylenediamine, 4-methylpentan-2-ol and 2-methylpentane, which were derived from the hydrogenation of 6PPD and MIBK and the hydrogenolysis of ketimine, respectively. 19,20,37 In contrast, a higher selectivity ($94.6%) could be obtained over activated carbon supported palladium sulde catalysts under the same reaction conditions but with a longer reaction time (5-6 h). Furthermore, Fig.…”

“…It is well known that the adsorption behaviour of substrates, which is highly dependent on the electronic structure of the surface of catalysts, plays an important role in the yield of products. 37 Side-on via s-donation and p-backdonation (i.e. s/p-adsorbed imine) are the most possible coordination states for the adsorption of the C]N bond and the C]O bond of ketimine and MIBK, respectively.…”

Modeling of bubble column slurry reactor for reductive alkylation of p-phenylenediamine

“…Lehtonen et al (1998) followed by Salmi et al (1999), developed a semi-batch slurry reactor model and loop reactor model for reductive alkylation of aromatic amines with short chain aldehydes (carbon chain length less than 3) using Pt/C catalyst. More detailed kinetic studies were reported from our group for reductive alkylation of aniline with acetone to N-isopropylaniline using Pd/Al 2 O 3 catalyst (Roy et al, 2005), and the more complex reductive alkylation of p-phenylenediamine (PPDA) with methyl ethyl ketone (MEK) to N, N -di-sec-alkyl-p-phenylenediamine, using Pt/Al 2 O 3 catalyst (Patil et al, 2007), wherein two amine functionalities are available for the alkylation reaction. A schematic of the reaction scheme considered in this work is shown in Fig.…”