HDS of 4,6-dimethyldibenzothiophene over CoMoS supported mesoporous SiO2-TiO2 materials

TiO2 supported SBA-15 (xTi@SBA-15) materials with various high TiO2 loadings (x = 25, 50 and 70 wt%) have been used as support for impregnation of CoMo active phase for the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (46DMDBT) as model molecule representative of gazole cuts. Compared to CoMoS supported over pure commercial TiO2 and conventional Al2O3, a higher total activity was measured corresponding to the presence of isomerization and dismutation reactions due to Brönsted acidity of TiO2. However, the HDS activity remains higher using alumina as support. Moreover, the DDS pathway was found favored to the HYD one with sulfided CoMo supported over xTi@SBA-15 catalysts contrary with alumina as support

Adsorption and Desorption of a Model Hydrocarbon Mixture Over HY Zeolite Under Dry and Wet Conditions

International audienceAdsorption behavior of a hydrocarbon mixture (propene, toluene, decane) mimicking Diesel cold-start was investigated under dry and wet conditions for commercial HY zeolites with a Si/Al ratio ranging from 2.5 to 100. Textural and structural characterizations were carried out using N-2 adsorption at 77 K and X-ray diffraction. In situ FTIR spectroscopy of adsorbed pyridine was exploited to probe acidic sites. The methodology used in this study consisted of adsorption phase at 35 degrees C with several kinds of mixtures followed by a Temperature-Programmed Desorption (TPD) at 10 degrees C/min. At high Si/Al ratio, a competitive thermodynamic adsorption between toluene and decane was demonstrated. To the opposite, propene is substantially not adsorbed whatever the Si/Al ratio of the zeolite. By decreasing the Si/Al ratio, the presence of large amounts of acidic sites enhances adsorption of unsaturated hydrocarbons. Water adsorption was found to be detrimental for HC storage due to hydrophilic nature

Influence of acid-base properties of the support on the catalytic performances of Pt-based catalysts in a gas-phase hydrogenation of acetonitrile

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HDS of 4,6-dimethyldibenzothiophene over CoMoS supported mesoporous SiO2-TiO2 materials

International audienc

Acidity study of X zeolites modified by nickel and/or chromium cations in the case of binary and ternary exchanges

International audienceA series of Ni(x)-, Cr(x) and CrNi(x)-exchanged X zeolites (x being the ion-exchange degree) was prepared and characterised by nitrogen adsorption, XRD. DTA/TGA and pyridine adsorption-desorption followed by IR spectroscopy. The objective is mainly to estimate quantitatively the number, strength and nature of acid sites and their dependence on the type of cation and its exchange level. A comparison between the binary and ternary exchanges was also established. The crystallinity and micropore volume losses were more significant for Cr(x)X and CrNi(x)X. The concentration of Lewis acid sites decreases with increasing the exchange degree for Cr(x)X and Ni(x)X, while it increases up to 39% for CrNi(x)X. An increase of the concentration of Bronsted sites was obtained. The fact that both the Lewis and Bronsted acidities markedly decrease between 423 and 623 K, proves that the available acid sites are overall weak. The pyridine desorption from the protonic sites is easier with CrNi(39)X than with Cr(39)X and Ni(40)X at 623 K, indicating a decrease in the strength in the case of ternary exchange. (C) 2012 Elsevier Inc. All rights reserved

Effect of gradual reduction of graphene oxide on the CO tolerance of supported platinum nanoparticles

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