Pierre Fouilloux

Homogeneous and Heterogeneous Hydrogenation of Nitriles in a Liquid Phase: Chemical, Mechanistic, and Catalytic Aspects

Abstract Primary or alkylated amines are important chemicals and intermedi-ates. N-Alkylamines are used without further transformation as surface-active agents. Aliphatic primary diamines polymerize with aliphatic diacids to give linear polyamides which have conquered a large place in textile and mechanical industry [11. Mono- and polyamines are produced by catalytic hydrogenation of the corresponding nitriles [2]. In particular this pathway to hexamethylenediamine has been made easier since the synthesis of adi-ponitrile by hydrocyanation of butadiene was made possible [3]. The spec-ifications for production of amines are often very drastic from the point of view of purity, in particular for the diamines used in the textile industry. Thus the stress is put on selectivity of the reaction and most of industrial processes have a yield approaching stoichiometry. It exists few reviews on reduction of nitriles [4, 51, the literature dealing with this type of reaction being mostly published in patents [6–91, an...

Monometallic Ni, Co and Ru, and bimetallic NiCr, NiTi and CoFe Ziegler-Sloan-Lapporte catalysts for the hydrogenation of adiponitrile into hexamethylenediamine: Effect of water and dopants

Abstract The catalytic hydrogenation of adiponitrile into hexamethylenediamine (HMD) under mild conditions (20 bar H2, 120 to 180°C) using monometallic Ni, Co and Ru and bimetallic NiCr, NiTi, NiCo and CoFe Ziegler-type catalysts is reported. It is found that water exerts a strong negative influence on the selectivity to the primary amine HMD whereas it has a spectacular beneficial effect on the catalyst activity, especially for Ni based catalysts. Adding a second metal (Cr, Ti) as a dopant for nickel has a beneficial effect on the selectivity in HMD but results in lower activities. The ratio Ni/M (M Cr, Ti) does not appear to be a key parameter in these systems as the doping effect on the HMD selectivity already appears at low dopant loading (atom.-%: 3% for Cr, 10% for Ti) and is constant up to 60%. The temperature has an influence on the HMD selectivity: the NiCr and NiTi catalysts show a peculiar behaviour, maintaining a high selectivity level (ca. 90%) over all the temperature range. This is not the case for the Co based catalysts.

Electrode potential of a dispersed Raney nickel electrode during acetone hydrogenation: Influence of the promoters

Abstract The hydrogenation of acetone was investigated in basic aqueous solution with (Co, Cr, Cu, Mo, Ti) doped and undoped Raney nickel catalysts. The reaction was carried out under pressure in an autoclave equipped with a reference electrode. The hydrogen consumption and the electrode potential were measured during the course of the reaction. Addition of Cr, Mo or Ti improves the activity in acetone hydrogenation while the activity of Co or Cu promoted catalysts remains similar to that of the undoped nickel. The kinetics obeys a Langmuir-Hinshelwood mechanism. A mathematical model was applied which fits well the experimental kinetic data. It allows the computation of the rate constant and the adsorption equilibrium constants. The metallic catalyst particles behave like a dispersed electrode and an electrochemical double layer is formed at their surface. In the presence of hydrogen alone, the metal potential is determined by the Nernst law for the hydrogen electrode. In the presence of acetone, the measured potential goes to the positive region for several tenths millivolts. The extent of the initial potential shift measured when acetone is introduced in the reactor is experimentally correlated with the physicochemical characteristics of the catalysts and their activities for acetone hydrogenation in the liquid phase.

Selective Hydrogenation of Adiponitrile (ADN) to Hexamethylenediamine (HMD) in the Liquid Phase on Raney Catalysts: Synergetic Effect Between the Base in the Solution and the Iron Dope on the Catalyst

Abstract This paper is devoted to the fundamental study of the doping effect of iron metal added to Ni-Al alloy precursor of Raney nickel catalysts. Their activities and selectivities in the liquid phase were determined taking into account the effect of the basicity of the solvent. The experiments were performed on catalysts coming from homogeneous NiAl 3 and Ni 2 Al 3 phases. A synergetic effect between the base in the solution and the iron dope in the catalyst was demonstrated.