scholarly journals Hierarchical Structure and Catalytic Activity of Flower-Like CeO2 Spheres Prepared Via a Hydrothermal Method

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 773 ◽  
Author(s):  
Genli Shen ◽  
Mi Liu ◽  
Zhen Wang ◽  
Qi Wang
Keyword(s):  
Catalytic Activity ◽  
Pore Size Distribution ◽  
Co Oxidation ◽  
Pore Size ◽  
Hydrothermal Method ◽  
Pore Volume ◽  
Average Diameter ◽  
Ceo2 Nanoparticles ◽  
Narrow Pore Size Distribution ◽  
Large Pore Volume

Hierarchical CeO2 particles were synthesized by a hydrothermal method based on the reaction between CeCl3·7H2O and PVP at 270 °C. The flower-like CeO2 with an average diameter of about 1 μm is composed of compact nanosheets with thicknesses of about 15 nm and have a surface area of 36.8 m2/g, a large pore volume of 0.109 cm3/g, and a narrow pore size distribution (14.9 nm in diameter). The possible formation mechanism of the hierarchical CeO2 nanoparticles has been illustrated. The 3D hierarchical structured CeO2 exhibited a higher catalytic activity toward CO oxidation compared with commercial CeO2.

scholarly journals Alumina/silica aerogel with zinc chloride as an alkylation catalyst

2001 ◽  
Vol 66 (10) ◽  
pp. 685-695 ◽  
Author(s):  
Aleksandar Orlovic ◽  
Djordje Janackovic ◽  
Sasa Drmanic ◽  
Zorica Marinkovic ◽  
Dejan Skala
Keyword(s):  
Catalytic Activity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Zinc Chloride ◽  
Pore Volume ◽  
Total Pore Volume ◽  
Chloride Content ◽  
Alkylation Catalyst

The alumina/silica with zinc chloride aerogel alkylation catalyst was obtained using a one step sol-gel synthesis, and subsequent drying with supercritical carbon dioxide. The aerogel catalyst activity was found to be higher compared to the corresponding xerogel catalyst, as a result of the higher aerogel surface area, total pore volume and favourable pore size distribution. Mixed Al-O-Si bonds were present in both gel catalyst types. Activation by thermal treatment in air was needed prior to catalytic alkylation, due to the presence of residual organic groups on the aerogel surface. The optimal activation temperature was found to be in the range 185-225 ?C, while higher temperatures resulted in the removal of zinc chloride from the surface of the aerogel catalyst with a consequential decrease in the catalytic activity. On varying the zinc chloride content, the catalytic activity of the aerogel catalyst exhibited a maximum. High zinc chloride contents decreased the catalytic activity of the aerogel catalyst as the result of the pores of the catalyst being plugged with this compound, and the separation of the alumina/silica support into Al-rich and Si-rich phases. The surface area, total pore volume, pore size distribution and zinc chloride content had a similar influence on the activity of the aerogel catalyst as was the case of xerogel catalyst and supported zinc chloride catalysts.

The relationship between geotechnical index properties and the pore-size distribution of compacted clayey silts

2015 ◽  
Vol 22 (6) ◽  
Author(s):  
Nazile Ural
Keyword(s):  
Specific Surface ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Correlation Coefficients ◽  
Liquid Limit ◽  
Index Properties

AbstractIn this study, the relationships between geotechnical index properties and the pore-size distribution of compacted natural silt and artificial soil mixtures, namely, silt with two different clays and three different clay percentages (10%, 20%, and 40%), were examined and compared. Atterberg’s limit tests, standard compaction tests, mercury intrusion porosimetry, X-ray diffraction, scanning electron microscopy (SEM) analysis, and Brunauer-Emmett-Teller specific surface analysis were conducted. The results show that the liquid limit, the cumulative pore volume, and specific surface area of artificially mixed soils increase with an increase in the percentage of clay. The cumulative pore volume and specific surface area with geotechnical index properties were compared. High correlation coefficients were observed between the specific areas and both the liquid limit and the plasticity index, as well as between the cumulative pore volume and both the clay percentage and the

Equilibrium moisture content in wet pressing of paper

TAPPI Journal ◽  
2020 ◽  
Vol 19 (7) ◽  
pp. 330-340
Author(s):  
RICHARD KEREKES ◽  
DAVID MCDONALD
Keyword(s):  
Energy Expenditure ◽  
Moisture Content ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Pore Volume ◽  
Limiting Factor ◽  
High Solids ◽  
Solute Exclusion ◽  
Chemical Pulping ◽  
Pulp Strength

Equilibrium moisture is a limiting factor in achieving high solids in the later stages of pressing or pressing low basis weight grades. We have developed a model that relates equilibrium moisture directly to the pore size distribution of fibers as measured by the solute exclusion technique. The model shows that chemical pulping and refining increase equilibrium moisture by increasing pore volume at given pore sizes in fibers, which leads to lower pressed solids and greater energy expenditure in the dryer section. Means to increase equilibrium moisture without compromising pulp strength are briefly discussed.

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