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Nanosized NiO, CeO and NiO-CeO mixed oxides with different Ni/Ce molar ratios were prepared by the soft template method. All the samples were characterized by different techniques as to their chemical composition, structure, morphology and texture. On the catalysts submitted to the same reduction pretreatment adopted for the activity tests the surface basic properties and specific metal surface area were also determined. NiO and CeO nanocrystals of about 4 nm in size were obtained, regardless of the Ni/Ce molar ratio. The Raman and X-ray photoelectron spectroscopy results proved the formation of defective sites at the NiO-CeO interface, where Ni species are in strong interaction with the support. The microcalorimetric and Fourier transform infrared analyses of the reduced samples highlighted that, unlike metallic nickel, CeO is able to effectively adsorb CO , forming carbonates and hydrogen carbonates. After reduction in H at 400 °C for 1 h, the catalytic performance was studied in the CO and CO co-methanation reaction. Catalytic tests were performed at atmospheric pressure and 300 °C, using CO/CO /H molar compositions of 1/1/7 or 1/1/5, and space velocities equal to 72000 or 450000 cm ∙h ∙g . Whereas CO was almost completely hydrogenated in any investigated experimental conditions, CO conversion was strongly affected by both the CO/CO /H ratio and the space velocity. The faster and definitely preferred CO hydrogenation was explained in the light of the different mechanisms of CO and CO methanation. On a selected sample, the influence of the reaction temperature and of a higher number of space velocity values, as well as the stability, were also studied. Provided that the Ni content is optimized, the NiCe system investigated was very promising, being highly active for the CO co-methanation reaction in a wide range of operating conditions and stable (up to 50 h) also when submitted to thermal stress.

Graphene oxide (GO) has been increasingly utilized in the fields of food, biomedicine, environment and other fields because of its benign biocompatible. We encapsulated two kinds of GO with different sizes on yeast cells with the assistance of polyelectrolytes poly (styrene sulfonic acid) sodium salt (PSS) and polyglutamic acid (PGA) (termed as Y@GO). The result does not show a significant difference between the properties of the two types of Y@GO (namely Y@GO1 and Y@GO2). The encapsulation layers are optimized as Yeast/PGA/PSS/PGA/GO/PGA/PSS based on the morphology, dispersity, colony-forming unit, and zeta potential. The encapsulation of GO increases the roughness of the yeast. It is proved that the Y@GO increases the survival time and enhance the activity of yeast cells. The GO shell improves the resistance of yeast cells against pH and salt stresses and extends the storage time of yeast cells.

Luanying He ,   Yulin Chang   et al.
A mixture of Pingdingshan lean coal and acid-treated Huadian oil shale was co-pyrolyzed in a drop-tube fixed-bed reactor in the temperature range of 300 °C–450 °C. To reveal the formation mechanism of the solid co-pyrolysis product, changes in some physicochemical properties were investigated, using analysis by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, pore analysis, thermogravimetry, and electron spin resonance. X-ray diffraction showed that the lattice plane spacing for the co-pyrolyzed mixture decreased from 0.357 nm to 0.346 nm and the average stacking height increased from 1.509 nm to 1.980 nm in the temperature range of 300 °C–450 °C, suggesting that pyrolysis treatment increased its degree of metamorphism. The amount of oxygen-containing functional groups and pore volume decreased with increasing temperature. Thermogravimetry and electron spin resonance results showed that synergistic effects occurred during the co-pyrolysis process. A formation mechanism for the solid product was proposed. Hydrogen-rich radicals generated from the pyrolysis of the oil shale were trapped by hydrogen-poor macromolecular radicals of the intermediate metaplast produced from coal pyrolysis, thereby increasing the yield of solid product.

Xiangchun Liu ,   Jun Hu   et al.

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