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Catalytic hydrodechlorination and hydrodearomatisation of 13 different mono-, di-, tri-, tetra- and pentachlorophenols were carried out simultaneously under mild reaction conditions (298–353 K, 0.3–0.5 MPa). Experimental conditions suitable for complete conversion of the pollutants into nontoxic cyclohexanol and sodium chloride were first determined using a commercial Ru/C catalyst. A new supported ruthenium catalyst was then designed that possesses a carbonaceous support suitable to concentrate chlorophenol through adsorption. Using parachlorophenol as a model molecule, the influence of the base concentration in solution and the kinetics of the reaction under chemical regime were studied. A p-chlorophenol→phenol→cyclohexanol consecutive kinetic scheme was considered that drove to numerous possible kinetic models. A dynamic simulation software was used both for helping in model discrimination and for kinetic parameter estimation. The estimated activation energy values amount to ca. 45.0±2.7 and 33.2±2.4 kJ mol−1 for the hydrodechloration and the hydrodearomatisation steps, respectively.

The hydrogenation of acetophenone in a slurry airlift reactor was conducted over a wide range of operating conditions. An important deactivation of the catalyst was experimentally observed and an empirical deactivation law was optimized. The deactivation rate constant increases with the inlet concentration and gas flow rate and decreases with the catalyst loading. The product selectivity measured in the slurry airlift reactor did not fit well with the computed one. The computation was performed using the results of the kinetic and hydrodynamic studies. A sensitivity analysis pointed out that the mass transfer is not limited. To perform a good fit with the experiments it was necessary to change some rate constants. This readjustment was justified by the difference in catalyst pretreatment between the continuous and the semi-batch reactor where significant catalyst pretreatment effects were shown.

In a first step the intrinsic kinetics of acetophenone hydrogenation on a Rh/C catalyst was studied in a semi-batch reactor. Tiny catalyst grains of 17 μm in average diameter were used in order to avoid any intraparticle diffusion limitation. Experiments were performed over a wide range of operating conditions and various Langmuir–Hinshelwood kinetic equations were discriminated over the complete conversion range. The model based on nondissociative adsorption of hydrogen and noncompetitive adsorption of the organic species with the gas molecules was found to fit better all the experimental data. The relevance of its optimized parameters was then discussed. In a second step the intraparticle diffusion limitations were also studied in a semi-batch reactor by varying the particle size. Two models based on the complex kinetics previously established were developed, taking into account the catalyst grain size and shape. After an additional adjustment of one of the adsorption constants ratios, they were found to provide a good representation of the data in terms of activity and selectivity.

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.

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.

The hydrogenation of acetone was investigated in basic aqueous solutions with undoped and chromium-doped catalysts. The reaction was carried out under pressure in an autoclave equipped with a reference electrode. The consumption of hydrogen and the electrode potential were measured during the course of the reaction. A mathematical model was applied which fits the experimental kinetic data well. It allows the computation of the rate constant and the adsorption equilibrium constants. The kinetics obey a Langmuir-Hinshelwood mechanism with competitive adsorption. 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 obeys the Nernst law for the hydrogen electrode. During acetone hydrogenation, the double layer is modified and the measured potential goes to the positive region for several tens of millivolts, depending on whether the catalyst is doped or not. In all cases an experimental correlation was found between this experimental potential rise and the reaction rate.

We prepared chromium promoted Raney nickel by two methods: catalysts of type I, by alkali leaching of Ni40-xCrx Al60 alloys (0.5 ⩽x ⩽ 2.2 ) and by soaking the catalyst obtained from Ni40Al60 alloy in an aqueous chromium chloride solution, catalysts of type II. The structure of these catalysts was investigated by measuring the total and metallic surface area, by micro-analysis at fine scale with analytical transmission electron microscopy, X-ray diffraction and Auger spectroscopy. For all the catalysts the STEM/EDX analysis showed essentially two types of agglomerates, one of them being detected more frequently. This component presented itself very similar whether the dope was introduced by a metallurgical process or by a chemical way, but the more rarely observed agglomerates were different. From Auger spectroscopy it appeared that the surface Cr/Ni atomic ratios were higher in the catalysts of type II than in the catalysts of type I.

The hydrogenation of acetophenone has been investigated in cyclohexane, with chromium promoted Raney nickel. The preparation and the physico-chemical properties of these catalysts have been described in part I. The reaction was carried out in a static reactor and its progress was followed by measuring the concentration of the components in the liquid phase. The ratios kibM/kjbN where ki, kj are the rate constants and bM, bN are the adsorption equilibrium constants for two competitive parallel reactions or two consecutive reactions, have been computed and used as selectivity criteria. These selectivity criteria allow to compare the activity of the different sites of hydrogenation. In the presence of chromium the hydrogenation of the C O bond is favoured with respect to the two side reactions: the hydrogenation of the aromatic ring and the hydrogenolysis of the C-OH bond. Catalysts prepared by soaking Raney nickel in an aqueous chromium chloride solution gave the highest selectivity in 1- phenylethanol.

IR emission spectra obtained with a Fourier transform spectrometer at 110/sup 0/C revealed that pyridine adsorbed on platinum Y zeolite by coordination to the Na ion and by formation of pyridinium ions with bands at 755 and 685 cm/sup -//sup 1/; the formation of pyridinium ions suggested the presence of acidic OH groups formed during platinum reduction with hydrogen. Bands observed at 465 and 2070 cm/sup -//sup 1/ in the spectra of adsorbed carbon monoxide were attributed to linearly adsorbed species, and a band at 1850 cm/sup -//sup 1/ to carbon monoxide bonded to two platinum atoms. The experimental technique and its scope are discussed.