In-situ Growth of Phosphorus-doped Boron Nitride on Commercial Alumina as a Robust Catalyst for Direct Dehydrogenation of Ethylbenzene

Direct dehydrogenation of ethylbenzene to styrene catalyzed by metal-free materials is one of the most challenging topics in the chemical industry currently. Here, PBN@Al2O3(N) synthesized by in-situ growth of phosphorus-doped...

Alumina-Toughened-Zirconia with Low Wear Rate in Ball-on-Flat Tribological Tests at Temperatures to 500 °C

An alumina-toughened zirconia (ATZ) material, fabricated using a procedure consisting of the common sintering of two different zirconia powders, was tested using the ball-on-disc method in a temperature range between room temperature and 500 °C. Corundum balls were used as a counterpart. The ATZ composite behaviour during tests was compared with that of commonly used α-alumina and tetragonal zirconia sintered samples. At temperatures over 350 °C, a drastic decrease in the wear rate of the material was detected. SEM analyses proved that, in such conditions, nearly the whole surface of the sliding material was covered with a layer of deformed submicrometric grains, which limited contact with the part of material that was not deformed. The mentioned layer was relatively strongly connected with the material, increased its resistance, and decreased its coefficient of friction. As a reference, commonly used materials, namely commercial alumina and tetragonal zirconia, were tested. The wear parameters of the composite were significantly better than those registered for the materials prepared of commercial powders.

Catalysis, Kinetic and Mechanistical Studies for the Transformation of Ethylene Glycol by Alumina and Silica Gel under Autogenous Pressure and Solvent-free Conditions

A kinetic and mechanistical studies of the new pathway for competitive transformation of ethylene glycol by alumina and silica gel have been described. Commercial alumina (Al com), synthetic alumina (Al syn), commercial silica gel (Si com) and synthetic silica gel (Si syn) were used for the transformation of ethylene glycol to a mixture of diethylene glycol, 1,4-dioxane and 2-methyl-1,3-dioxolane via acetaldehyde by heating at 150 °C under autogenous pressure without solvent. The results show that the yield of these three products strongly depends on the nature of the used catalyst and the reaction time.

The Way of Utilization of Fused Corundum Dust Waste for the High-Alumina Chamotte Production

High-alumina chamotte with an Al2O3 content of more than 62% is a desirable raw material to produce high-alumina refractories. The production of high-alumina aggregate (chamotte) is carried out in various ways, using plastic or semi-dry technology for briquetting from commercial alumina and refractory clay. When grinding fused corundum, the dust containing 93–95% Al2O3 is formed; it is currently a substandard material. It is of interest to involve this waste product in the production of high-alumina chamotte. The developed technology allows obtaining the desirable material and utilizing production waste. In this project the briquetting parameters to produce high-alumina chamotte using corundum waste and refractory enriched kaolin were determined.

Hydrocracking of Light Diesel Oil over Catalysts with Industrially Modified Y Zeolites

Three industrially modified Y zeolites with a hierarchical structure were characterized by XRD, N2 adsorption–desorption, SEM, TEM, 27Al-/29Si-NMR, in situ pyridine-FTIR, and NH3-TPD techniques. The industrial hydrocracking catalyst of light diesel oil was prepared by kneading and extruding the mixture of 10 wt.% industrially modified zeolite, commercial alumina, nickel nitrate, and molybdenum oxide. The small amount of hierarchical Y zeolite in the hydrocracking catalyst plays a key role, resulting in selective hydrogenation of naphthalene and further ring-opening activity. The mesoporous structure of the zeolites provided an effective interface and improved the accessibility of acid sites to bulky reactants.

New Trends in Automotive Exhaust Gas Purification Materials: Improvement of the Support against Stability of the Active Components

Lanthanum and zirconium oxides are well known to be applied as an additive to improve the properties of the commercial alumina. Such modified aluminas are widely used in different catalytic fields including three-way catalysis. In the present research we have paid attention to the possible effects of the doping on the catalytic performance and stability of bimetallic Pd-Rh catalysts. The samples were prepared via an incipient wetness impregnation of the commercial supports, tested in CO oxidation under prompt thermal aging regime and characterized by physicochemical methods.

Microstructural and Mechanical Properties of Al2O3/HAp Composites for Use as Bone Substitute Material

This work involved the development of alumina/hydroxyapatite (Al2O3/HAp) composites for use as bone graft material in maxillofacial reconstruction. The effect of introducing 20 and 30 wt% of hydroxyapatite into the alumina matrix was also investigated. The composites were produced from hydroxyapatite synthesized by the precipitation method, using commercial alumina as a matrix. Samples of the composite material were compacted under 260 MPa of isostatic pressure, followed by sintering at 1200°C/2h and characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diametral compression. The XRD results confirmed the presence of Al2O3 and Ca10(PO4)6(OH)2 – HAp crystalline phases in all composites. The addition of HAp to the alumina matrix inhibited alumina grain growth, reducing intergranular porosity and thus promoting greater densification and mechanical strength of the composites.