José M. López Nieto

Promoted NiO Catalysts for the Oxidative Dehydrogenation of Ethane

Metal oxide promoted NiO catalysts with a Ni/(Mexa0+xa0Ni) atomic ratio 0.92xa0have been investigated for the oxidative dehydrogenation of ethane. These materials have been characterized by several techniques (N2-adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy of adsorbed CO and ethylene). The nature of surface sites is strongly influenced by the valence and the acid/base characteristics of the metal oxide promoters, which have a great impact on the selectivity to ethylene. Accordingly, a clear correlation between selectivity to ethylene and the valence of the promoter has been observed in the present work. Additionally, the acidity of the catalyst also enhances the selectivity to ethylene.

Silica supported copper and cerium oxide catalysts for ethyl acetate oxidation

The formation of active sites in the silica supported copper and cerium oxide bi-component catalysts for total oxidation of ethyl acetate was studied by Nitrogen physisorption, XRD, XPS, UV-Vis, Raman, FTIR of adsorbed CO spectroscopies and TPR. It was found that the interaction between the copper oxide nanoparticles and the supported on the silica ceria ones is realized with the formation of interface layer of penetrated into ceria lattice copper ions in different oxidative state. This type of interaction improves the dispersion of copper oxide particles and provides higher accessibility of the reactants to the copper active sites even at low copper amount.

The hydrothermal synthesis of tetragonal tungsten bronze-based catalysts for the selective oxidation of hydrocarbons

Mixed metal oxides with tetragonal tungsten bronze (TTB) structure, showing high activity and selectivity for the gas phase partial oxidation of olefins, have been prepared by hydrothermal synthesis from Keggin-type heteropolyacids.

Gas phase heterogeneous partial oxidation reactions

Abstract Mixed metal oxides are used as catalysts in the gas phase partial oxidation of hydrocarbons. This paper will present the principles of catalyst choice for selective oxidation reactions as well as the structural features of metal oxide catalysts. The nature of active sites in selective oxidation reactions will also be briefly discussed. We will pay special attention to several representative reactions: (1) ODH of short chain alkanes (from C1 to C4), (2) propene partial oxidation/ammoxidation on bismuth molybdate based catalysts, (3) n-butane direct oxidation to maleic anhydride on VPO type catalysts, and (4) propane direct oxidation/ammoxidation on mixed MoVTe(Sb)Nb–O catalysts. Finally, the future trends in partial oxidation processes especially focusing on the use of biomass as a raw material will be presented.

Mesoporous Phosphate Heterostructures: Synthesis and Application on Adsorption and Catalysis

Porous phosphate heterostructures (PPHs) are solids formed by a layered metal(IV) phosphate expanded with silica galleries obtained by combining the two main strategies for obtaining mesoporous materials [pillared layered structures (PLS’) and MCM-41]. The different synthetic pathways for obtaining mesoporous phosphate structures with silica galleries with Zr- or Ti-doped silica, the study of their structural, textural and acid properties, its functionalisation with different organic substances such as propionitrile, 3-aminopropyl triethoxysilane, (3-mercaptopropyl)trimethoxysilane, vinyltrimethoxysilane, phenyltriethoxysilane and 3-(triethoxysilyl)propionitrile are discussed. The preparation of metal-supported catalysts and their application in gas separation, adsorption and catalysis are reviewed. Specifically, the use of Cu- and Fe-exchanged PPH for the adsorption of benzothiophene and the separation of propane/propene is the main application as adsorbent. The hydrotreating of aromatic hydrocarbons using ruthenium-impregnated catalysts via hydrogenation and hydrogenolysis/hydrocracking for the production of clean diesel fuels, the selective catalytic reduction of NO from stationary and mobile sources by using Cu–PPH with 1, 3 and 7 wt% of Cu and the selective oxidation of hydrogen sulphide to sulphur with vanadium-containing PPH are the three catalytic reactions of environmental interest studied.