Pd catalysts with varying particle size supported on a high-surface-area (600 m2/g) SiO2 were prepared by wet impregnation. The kinetics of vinyl acetate (VA) synthesis at atmospheric pressure was investigated in a fix-bed microreactor. With transmission electron microscopy (TEM), the average diameter of the Pd particles was estimated to be 4.0 ± 0.2 and 2.5 ± 0.1 nm over the reduced Pd(5.0 wt%...

Mechanistic insight into the semihydrogenation of 1-butyne and 2-butyne on Cu nanoparticles supported on partially dehydroxylated silica (Cu/SiO2-700) was obtained using parahydrogen. Hydrogenation of 1-butyne over Cu/SiO2-700 yielded 1-butene with ≥97% selectivity. The surface modification of this catalyst with tricyclohexylphosphine (PCy3) increased the selectivity to 1-butene up to nearly 10...

p2o5-sio2 (30% w/w) was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles under solvent-less and in solvent conditions from o-phenylenediamine and aldehydes. the products were directly recrystallized from methanol.

A sample of MoOx/SiO2, in which all of the Mo cations are present as isolated mono-oxo molybdate moieties, was prepared and investigated to understand the redox chemistry of such molybdate species and their ability to exchange oxygen with O2 and H2O. Raman spectroscopy was used to monitor the exchange of 18O for 16O in the Mo=O bond of isolated molybdate species, whereas mass spectrometry was u...

in this work, zno/sio2 nanoparticles were prepared using sol-gel method, and platinum particles were loaded on zno/sio2 nanoparticles by photoreductive method. samples were characterized by x-ray diffraction (xrd), scanning electron microscopy (sem) and fourier transform infrared spectroscopy (ft-ir). the xrd patterns showed that the zinc oxide samples have a wurtzite structure (hexagonal phase...

The depolymerization of lignin to bioaromatics usually requires a hydrodeoxygenation (HDO) step to lower the oxygen content. A mixed Cu-Mg-Al oxide (CuMgAlO x ) is an effective catalyst for the depolymerization of lignin in supercritical ethanol. We explored the use of Ni-based cocatalysts, i.e. Ni/SiO2, Ni2P/SiO2, and Ni/ASA (ASA = amorphous silica alumina), with the aim of combining lignin de...

The aromatic rings of polystyrene (PS) were hydrogenated in decahydronaphthalene (DHN) expanded with supercritical carbon dioxide (scCO2). Conducting the hydrogenation in scCO2-DHN offers the benefits of improved transport properties, specifically lower solution viscosity and a higher PS diffusion coefficient. Various Pd catalysts are effective for hydrogenating the aromatic rings of PS at temp...

the use of a recyclable phase transfer catalyst, sio2-peg-imbr, is demonstrated in a simple and highly efficient synthesis of phenacyl derivatives by nucleophilic substitution reaction of phenacyl halides with different anions in water. advantages of this system are easy work-up, moderate to good yields, and recyclable catalyst. the catalyst can be recycled and reused several times with no loss...

A triethylaluminium(TEAl)-modified Phillips ethylene polymerisation Cr/Ti/SiO2 catalyst has been developed with two distinct active regions positioned respectively in the inner core and outer shell of the catalyst particle. DRIFTS, EPR, UV-Vis-NIR DRS, STXM, SEM-EDX and GPC-IR studies revealed that the catalyst produces simultaneously two different polymers, i.e., low molecular weight linear-ch...

Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.