Showing papers in "Catalysis Today in 1988"

TL;DR: In this article, a synthese sur les argiles colonnaires qui aborde les problemes suivants: realisation de la structure colonnaire a l'aide d'hydroxy-polymeres d'Al, Zr ou Ti, stabilisation des piliers and des feuillets, applications au craquage catalytique fluide.

TL;DR: In this paper, the authors discuss the modes of preparation of catalyseurs sulfures (par precipitation a partir de solutions aqueuses ou sulfuration de metal ou d'oxyde).

TL;DR: In this article, the source d'acidite and des sites acides ainsi que de l'influence de la structure colonnaire sur l' acidite and la stabilite des argiles.

TL;DR: In this paper, the sulphidation of a nickel-tungsten catalyst has been studied by XPS and electron microscopy and it was observed that for a sulphidation temperature of 400°C, only 70% of the tungsten atoms are in a WS 2 -like form; this proportion increases to 95% at 650°C.

TL;DR: In this article, active sites are created on the surface of a Li/MgO catalyst used for the selective oxidation of methane, by the gradual loss of CO 2 from surface lithium carbonate species in the presence of oxygen.

TL;DR: In this paper, a Mars-van Krevelen type mechanism was proposed in which methyl radicals were formed at surface metal oxide sites and subsequently dimerize or react with other hydrocarbons in the gas phase.

TL;DR: In this article, the authors studied the catalytic properties of nitrogen-containing model compounds such as pyridine, quinoline, acridine, pyrrole and carbazole and found that saturation of the heteroaromatic rings always occurs prior to any cleavage of C-N bonds.

TL;DR: In this article, the authors proposed a recirculating solids riser reactor for the oxidation of butane to maleic anhydride, where the organic is oxidized in a reiser reactor zone using oxidized catalyst and reduced catalyst is reoxidized to its optimum state in a separate fluidized bed regenerator zone.

TL;DR: Delaminated clays are solid supports and catalysts characterized by a house-of-card like structure containing mesopores and macropores characteristic of mixed oxides, aluminas and silicas.

TL;DR: In this paper, the effects of the number of active sites and the pore volume of the zeolites on the initial rate of coke formation and the final coke level are studied.

TL;DR: In this article, a review of MAS NMR studies of unpillared and pillared clays with Al13-Oligomer Oligomer is presented, and it is shown that the pillaring agent is either the Al13 Keggin-like cation or a polymer of Al13.

TL;DR: In this paper, it was shown that by knowing the reactivity of individual solids, including the catalyst precursors, and their crystal chemistry, a better understanding of the catalytic system in the structure-sensitive oxidation of linear C4-hydrocarbons is expected.

TL;DR: In this paper, solid-state ion exchange of protons of acidic and non-acidic OH groups for alkaline earth cations in mordenite-type zeolites was investigated by means of TGA, temperature-programmed evolution of gases, IR and in-situ IR/GC measurements.

TL;DR: In this article, in-situ IR spectroscopy using dealkylation/disproportionation of ethylbenzene as a model reaction was used to investigate coke formation over a series of dealuminated mordenites.

TL;DR: In this article, the authors compared the reactivities of linear, branched and cyclic alkanes with vanadyl pyrophosphate catalyst in the heterogeneous oxidation of C1-C7 alkane series and concluded that the driving force is the formation of corresponding olefins and the rate determining step is the contemporaneous removal of two H atoms by a concerted mechanism.

TL;DR: In this paper, a comparison of the methacrolein yields in isobutene oxidation over identical weights of mixtures of different compositions is presented, showing a dramatic synergy: for adequate proportions (Sb{sub 2}O{sub 4}/(Sb ∆ O ∆ + Sno ∆ = 0.3-0.6) the yield is multiplied by a factor of ten, compared to the added yields which would be reached with the corresponding weights of the simple oxides, if isolated.

TL;DR: In this article, it was shown that not only hydroxyl ions but also sodium ions played an important role in the nucleation of ZSM-23, which was synthesized in the presence of pyrrolidine.

TL;DR: In this article, low temperature adsorption of molecular hydrogen with IR examination of its perturbation was used as a molecular probe in the study of dehydroxylation of decationized high-silica zeolites.

TL;DR: In this article, the authors report on the characterisation of several ceria supported rhodium catalysts and show that at 773 K the adsorption capability of these catalysts is significantly reduced.

TL;DR: In this article, an approach of selectivity issues combining surface structure with kinetic concepts is presented, in an attempt to develop a generalized dynamic understanding of oxide-based catalysts, in particular, the model considers the effect of reaction conditions (composition of reactants and reaction temperature) on catalyst selectivity and offers a key to the interpretation of the catalytic behavior of mixed metal oxides of modified redox properties.

TL;DR: In this article, the variation of initial rates with partial pressures of oxygen, toluene and ammonia was determined for the formation of carbon oxides in ammoxidation of toluenes over a V2O5 catalyst.

TL;DR: In this paper, the authors discuss the catalytic catalytique d'argiles colonnaires, au Cours de l'hydrocraquage de gasoil sous vide, lorsqu'elles sont parties constituantes du catalyseur ou de son support

TL;DR: In this article, the vibrational spectra (LRS and FTIR) were modified by introducing different bases (CH3)2O, NH3, C5H5N) which react with unsaturated sites on the W atom.

TL;DR: In this paper, 1-and 2-methylnaphthalene were reacted over acid zeolites with different pore widths, viz. HZSM-5, HY and HY-12, in a flow-type i.r. cell.