Sulfonated hydrothermal carbons show high activity for esterification of palmitic acid with alcohols. However, the catalyst is significantly deactivated upon recovery. Leaching of sulfonated species does not account for this deactivation, which is observed even by pretreatment only with the alcohol under reflux. Solid state NMR shows the presence of chemically bound alkyl groups coming from the alcohol, clearly different from strongly physisorbed species obtained by pretreatment at room temperature. The formation of sulfonate esters accounts for the deactivation behavior in reactions taking place in alcohols as solvents, mainly with methanol due to its higher reactivity.

No abstract

No abstract

N-doped carbon nanofibers with various nitrogen contents and chemistries have been grown on cordierite monoliths by varying the synthesis conditions. Ru has been impregnated on the N-doped CNFs, on undoped CNFs, H2O2-treated CNFs, and alumina coated monoliths. These catalysts have been characterized (XPS, TPR, STEM, CO chemisorption) after several preparation stages and they have been tested in ammonia decomposition. It has been found that nitrogen doping contributes to stabilize Ru to a small particle size and in a reduced state. The strong interaction of the precursor with the nitrogen groups enables the preparation of small Ru nanoparticles, uniformly distributed throughout all the CNFs coating the monolith. Catalysts supported on N-doped CNFs have exhibited NH3 decomposition activities higher than catalyst on N-free CNFs. It has been evidenced that the catalyst with the highest amount of nitrogen facilitates keeping Ru in reduced state upon air exposure. This enhanced reducibility correlates with substantially higher TOF in ammonia decomposition than for the other catalysts supported on CNFs with various functionalizations.

No abstract

No abstract

a b s t r a c tTitanium centers grafted on hydrophobic silica bearing long chain silanes (octadecyl or octyl) are able to oxidize dibenzothiophene (DBT), as well as simpler sulfides and 2,6-dimethyldibenzothiophene, to the corresponding sulfone in hydrocarbon solution with aqueous hydrogen peroxide in only a slight excess over the stoichiometric amount, without using any surfactant or cosolvent. The productivity per gram of catalyst or per Ti site can be optimized by tuning the silanization of the silica (or using a commercially available silanized silica) and the Ti loading of the catalyst. The catalyst preparation and the oxidation reaction are compatible with the use of an industrial grade aromatic solvent.

Ru nanoparticles were supported on monoliths that were coated with variously functionalized carbon nanofibers (CNFs), that is, un‐doped CNFs, CNFs that had been post‐treated with H2O2, and CNFs that had been doped with nitrogen during their growth. The Ru uptake (by equilibrium adsorption) onto N‐doped CNFs was larger compared to that on their un‐doped and O‐doped counterparts. The functionalization of the CNF support did not play a significant role in determining the size of the deposited Ru nanoparticles, but it substantially impacted on the sintering under the reaction conditions and on the electron density of the reduced metal. Among the catalysts on the different CNF supports, Ru on N‐CNF exhibited the highest H2 productivity from ammonia decomposition, which pointed to electronic effects that were induced by functionalization of the support.