Effect of structural ordering of the carbon support on the behavior of Pd catalysts in aqueous-phase hydrodechlorination

Catalysts consisting of Pd supported on virgin and heat-treated carbon blacks (homemade and commercial), graphites (natural and synthetic) and commercial carbon nanofibers were prepared and tested in the aqueous phase hydrodechlorinaton (HDC) of 4-chlorophenol (4-CP) under near ambient conditions (30 °C, 1 atm) in order to explore the effect of the support on the catalytic behavior. The homemade graphitized supports were prepared from commercial carbon black (CB) and from a carbon black-like material (CBPE) obtained from pyrolysis of low-density polyethylene. All the catalysts prepared yielded complete 4-CP conversion, although a wide range of activity was observed (10.7–173.5 mmol gPd−1 min−1). The graphitized carbon black provided the most active catalysts, showing Pd nanoparticles around 3 nm in size and a well-balanced contribution of Pd species (Pdn+/Pd0 = 0.9). Substantial differences of activity were found between the graphitized and not graphitized supports, even for catalysts with similar Pd nanoparticle size. The higher activity of the catalysts with graphitized supports can be partly associated to a more balanced initial Pdn+ to Pd0 ratio. Moreover, higher selectivity to hydrogenation products (cyclohexanone) was also achieved with those catalysts due to a higher contribution of the Pd0 speciesThe authors greatly appreciate financial support from the Spanish MINECO (CTQ2012-32821

Nalaz tetratiridija u peritonealnoj šupljini sijamske mačke.

Peritoneal tetrathyridiosis in a 6-year-old male Siamese cat is described. Abdominal distension and mass were determined at clinical examination. Parasitic materials, which were free in the peritoneum and attached to the inner body wall and viscera, were viewed macroscopically. Microscopically chronic multiple pyogranulomatous peritonitis, hepatitis and splenitis were observed. Parasites were identified as tetrathyridia of Mesocestoides sp., probably Mesocestoides lineatus.Opisana je peritonealna tetratiridioza u šestogodišnje sijamske mačke. Kod kliničke pretrage ustanovljena je abdominalna distenzija i povećana masa. Makroskopski su utvrđeni slobodni parazitski elementi u trbušnoj šupljini te priljubljeni na unutarnju stranu trbušne stijenke i na crijeva. Mikroskopski je ustanovljen kronični multipli piogranulomatozni peritonitis, hepatitis i splenitis. Identificiran je tetratiridij Mesocestoides, vjerojatno Mesocestoides lineatus

Characterization of deposits formed on diesel injectors in field test and from thermal oxidative degradation of n-hexadecane in a laboratory reactor

Solid deposits from commercially available high-pressure diesel injectors (HPDI) were analyzed to study the solid deposition from diesel fuel during engine operation. The structural and chemical properties of injector deposits were compared to those formed from the thermal oxidative stressing of a diesel fuel range model compound, n-hexadecane at 160°C and 450 psi for 2.5 h in a flow reactor. Both deposits consist of polyaromatic compounds (PAH) with oxygen moieties. The similarities in structure and composition of the injector deposits and n-hexadecane deposits suggest that laboratory experiments can simulate thermal oxidative degradation of diesel in commercial injectors. The formation of PAH from n-hexadecane showed that aromatization of straight chain alkanes and polycondensation of aromatic rings was possible at temperatures as low as 160°C in the presence of oxygen. A mechanism for an oxygen-assisted aromatization of cylcoalkanes is proposed