Diffusion Measurements of Hydrocarbons in Zeolites with Pulse-Field Gradient Nuclear Magnetic Resonance Spectroscopy

Pulse field gradient NMR technique was used to determine self-diffusivity of heptane and pentadecane at room temperature for microporous catalysts, used both as powders and shaped with a binder extrudates. The results showed that diffusivities increased with increasing specific surface area, micro- and mesopore volume of the studied catalysts. The presence of Bindzil binder together with H-Beta-25 decreased hydrocarbon diffusivities. Self-diffusivities of heptane and pentadecane were smaller for extrudates than for the powder catalysts. The detailed information about mass transfer limitations is needed to further process optimization since effective diffusivity is directly correlated with self-diffusion coefficients. The estimates of the ratio of porosity and tortuosity were also determined. The diffusion measurements with relatively long observation times Delta (20 up to 1000 ms) and catalysts fully immersed in pentadecane revealed that a small portion of sites exhibits very small diffusivities in H-Beta-25-Bindzil extrudates, which is correlated with a low ratio of mesopore to micropore volumes of this material

Determination of acid sites in porous aluminosilicate solid catalysts for aqueous phase reactions using potentiometric titration method

A potentiometric acid base titration method was developed to characterize the acid base properties of H-Beta-25, H-Beta-300, H-Ferrierite-20 and Si-MCM-48 zeolites in aqueous solutions. The method is based on linearization of the titration curve. The zeolite powders were dispersed in a sodium nitrate solution which was then titrated with a standard solution of sodium hydroxide. Various acid sites were found in the studied zeolites, and both the protonation constants and the concentrations of these acid sites were determined. The chemical composition (aluminum and silicon), distribution of the aluminum sites, crystallinity as well as the acidic properties of the titrated zeolites were compared with those of the pristine zeolites by using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), X-ray Diffraction (XRD), Al-27 NMR spectroscopy and the commonly used gas phase Fourier Transform Infrared spectroscopy (FTIR) of pyridine adsorption method. (C) 2015 Elsevier Inc. All rights reserved.</p

Hydrodeoxygenation of Isoeugenol over Ni- and Co-Supported Catalysts

Hydrodeoxygenation (HDO) of isoeugenol was investigated over several Ni (Ni/SiO2, Ni/graphite) and Co (Co/SBA-15, Co/SiO2, Co/TiO2, Co/Al2O3) catalysts at 200 and 300 degrees C under 30 bar hydrogen pressure in a batch reactor. The catalysts were prepared by an impregnation method and systematically characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and energy dispersive analysis, organic elemental, and thermogravimetrical analysis before and after the reaction. Analysis of the liquid, solid, and gaseous products was performed to identify isoeugenol transformation pathways. The maximum yield of the desired propylcyclohexane (PCH) (63%) and the highest sum of masses of reactants and products in the liquid phase based on GC results (GCLPA) (79%) were obtained over 10 wt % Co/SBA-15. HDO of isoeugenol over 11 wt % Co/SiO2 resulted in 50% PCH yield with a rather similar GCLPA of 73%. Low yields of PCH and the liquid phase mass balance closure were obtained over highly dispersed 15 wt % Co/Al2O3 and 15 wt % Co/TiO2. PCH yield was 60% over Ni/graphite and 44% over Ni/SiO2 after 4 h with GCLPA values of 73 and 70%, correspondingly. Overall PCH yields increased in the following order: Co/TiO2 < Co/Al2O3 < Ni/SiO2 < Co/SiO2 < Ni/graphite < Co/SBA-15. Regeneration and reuse of industrially relevant 11 wt % Co/SiO2 was succesfully demonstrated

Hydrodeoxygenation of Isoeugenol over Alumina-Supported Ir, Pt, and Re Catalysts

Hydrodeoxygenation (HDO) of isoeugenol (IE) was investigated using bimetallic iridium rhenium and platinum rhenium catalysts supported on alumina in the temperature and pressure ranges of 200-250 degrees C and 17-40 bar in nonpolar dodecane as a solvent. The main parameters were catalyst type, hydrogen pressure, and initial concentration. Nearly quantitative yield of the desired product, propylcyclohexane (PCH), at complete conversion in 240 min was obtained with Ir-Re/Al2O3 prepared by the deposition-precipitation method using 0.1 mol/L IE initial concentration. High iridium dispersion together with a modification effect of rhenium provided in situ formation of the IrRe active component with reproducible catalytic activity for selective HDO of IE to PCH. The reaction rate was shown to increase with the increasing initial IE concentration promoting also HDO and giving a higher liquid phase mass balance. Increasing hydrogen pressure benefits the PCH yield

Search for neutral MSSM Higgs bosons decaying to a pair of tau leptons in pp collisions

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Measurement of top quark–antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV

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Searches for electroweak production of charginos, neutralinos, and sleptons decaying to leptons and W, Z, and Higgs bosons in pp collisions at 8 TeV

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Measurement of prompt J/ψ pair production in pp collisions at √s = 7 Tev

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Study of hadronic event-shape variables in multijet final states in pp collisions at √s=7 TeV

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