The synthesis of a large number of fine chemicals, particularly in the field of flavor and fragrance chemistry [1,2] and pharmaceuticals [3], involves the selective hydrogenation of unsaturated carbonyl intermediates as a critical step. The hydrogenation of α,β-unsaturated carbonyls into saturated carbonyls is comparatively easy to achieve because thermodynamics favor the hydro-genation of the C═C bonds; therefore, research efforts were more directed at improving the selectivity to unsaturated alcohols. When a substituent is present on the carbon atom of the carbonyl group (i.e. with ketones), there is no chance to hydrogenate selectively the C═O bond, and saturated ketones are obtained with a high yield. This review is thus mostly restricted to the hydrogenation of α, β-unsaturated aldehydes into the corresponding unsaturated alcohols.

Selective Hydrogenation of α,β-Unsaturated Aldehydes

High aromatic content in diesel fuel has been recognized both to lower the fuel quality and to contribute significantly to the formation of undesired emissions in exhaust gases [1, 2]. Because of the health hazards associated with these emissions, environmental regulations governing the composition of diesel fuels are being tightened in both Europe and the United States, leading to limitations on aromatics [3, 4].

Aromatic Hydrogenation Catalysis: A Review

Removal of nitrogen monoxide from exhaust gases through novel catalytic processes

The reforming of methane with carbon dioxide was studied over nickel supported on MgO, TiO2, SiO2, and activated carbon. The influence of the support on catalyst activity and carbon deposition resistivity was markedly different ineach case. Although considerable formation of filamentous carbon was observed over Ni/SiO2 (confirmed by TEM and TPO), there was negligible initial loss of catalytic activity. The catalytic activity of Ni/C was very similar to that of Ni/SiO2, but no filamentous carbon appeared to be formed. In contrast to Ni/SiO2, substantially less coking was observed over either the Ni/TiO2 or the Ni/MgO catalysts. Evidence of strong metal-support interaction (SMSI) in the Ni/TiO2 catalyst indicated that large ensembles of nickel atoms, active for carbon deposition, are deactivated or removed by the presence of mobile TiOx species. The identification of two TiOx phases and a Ni5TiO7 phase was made possible by direct measurement of crystalline d spacings with TEM. The Ni/MgO catalyst was both active and very stable for up to 44 h time on stream. Chemisorption, XRD and TEM results indicate the formation of a partially reducible NiO—MgO solid solution, which appears to stabilize the reduced nickel surfaces and provide resistance to carbon deposition.

Catalytic reforming of methane with carbon dioxide over nickel catalysts I. Catalyst characterization and activity

Copper-based catalysts are active in a wide range reactions of transformation of nitrogen oxides and represent an useful model system to better understand the fundamental aspects of the chemistry and mechanism of reaction of catalytic transformation of these pollutants. After an introduction on the reactivity of copper-based catalysts (supported and unsupported copper oxide, Cu-zeolites, cuprates and other copper compounds) in various reactions of conversion of nitrogen oxides, four main sub-topics are discussed in detail: (i) nature of copper species, (ii) chemisorption and surface transformations of NO, (iii) relationship between copper species and activity in the conversion of nitrogen oxides and (iv) mechanism of reduction of nitrogen oxides to N 2 . Five reactions of transformation of nitrogen oxides are discussed in detail: (i) decomposition of NO, (ii) reduction of NO with ammonia in the presence or not of oxygen, (iii) reduction of NO with hydrocarbons in the presence of oxygen, (iv) reduction of NO with CO and (v) decomposition of N 2 O. The mechanism of reduction of nitrite and N 2 O by copper enzymes is also discussed, with a view to provide some useful insights on the chemistry of transformation. In this review particular attention is directed towards controversial points in the literature, underestimated questions, and hypothesis and theories which do not allow interpretation of all sets of experimental data. Discussion is also focused on the presence of multiple and competitive pathways of transformation, the relative roles of which depend on reaction conditions.

Nature of active species in copper-based catalysts and their chemistry of transformation of nitrogen oxides

Location and dispersion of platinum in PtY zeolites

Introduction B. Imelik, J.C. Vendrine. Infrared Spectroscopy G. Coudurier, F. Lefebvre. Raman Spectroscopy E. Garbowski, G. Coudurier. Electronic Spectroscopy E. Garbowski, H. Praliaud. Nuclear Magnetic Resonance in Homogeneous and Heterogeneous Catalysis Y. Ben Taarit, J. Fraissard. Electron Paramagnetic Resonance M. Che, E. Giamello. Ferromagnetic Resonance L. Bonneviot, D. Olivier. Mossbauer Spectroscopy P. Bussiere. Auger Electron Spectroscopy J.C. Bertolini. Secondary Ion Mass Spectroscopy J. Grimblot, Abon. Ion Scattering Spectroscopy J. Grimblot, M. Abon. Applications of Neutron Scattering to Catalysis H. Jobic. X-Ray Absorption Spectroscopy B. Moraweck. Determination of the Atomic Structure of Solid Catalysis by X-Ray Diffraction G. Bergeret, P. Gallezot. Small Angle X-Ray Scattering A.J. Renouprez. Photo-Electron Spectroscopies J.C. Vendrine. Photo-Electron Diffraction and Surface Crystallography Y. Jugnet. 7 additional articles. Index.

Boris Imelik

Papers

Location and dispersion of platinum in PtY zeolites

Catalyst Characterization: Physical Techniques For Solid Materials

X-ray diffraction study of cupric ion migrations in two Y-type zeolites containing adsorbed reagents

PtMo bimetallic catalysts supported on Y-zeolite: I. Characterization of the catalysts

Location of nickel ions in Y zeolites. II. Influence of various reagents adsorption on nickel positions