Authors:Nilgün Yener, Müşerref Önal, Gökçe Üstünışık, and Y. Sarıkaya
An industrial raw material taken from Beypazarı (Ankara, Turkey) region was heated at different temperatures in the 100–1100�C
interval for 2 h. The volumetric percentage of particles having diameter below 2 μm in an aqueous suspension of the material
held 24 h were determined as 85% by the particle size distribution analysis. The mineralogical composition of the material
was obtained as mass% of 81% sepiolite, 15% dolomite, and 4% interparticle water by using the X-ray diffraction (XRD) and
thermal analysis (TG, DTA) data. The temperature ranges were determined for the dehydrations of the interparticle water and
the zeolitic water as 25–340�C, for the dehydration of the bound water as 340–580�C, and for the dehydroxylation of the hydroxyls
as 800–833�C in the sepiolite. The zig-zag changes in the specific surface area (S/m2 g−1) and specific micro-and mesopore volume (V/cm3 g−1) with the temperature increases were discussed according to the dehydrations and dehydroxylation of the sepiolite.
Authors:V. Balek, L. Pérez-Maqueda, J. Poyato, Z. Černý, V. Ramírez-Valle, I. Buntseva, and J. Pérez-Rodríguez
The effect of grinding
on thermal behavior of pyrophyllite and talc as commonly used ceramic clay
minerals was investigated by DTA, TG, emanation thermal analysis (ETA), B.E.T.
surface area (s.a.) measurements, X-ray diffraction (XRD) and scanning electron
A vibratory mill was used in this study, grinding
time was 5 min. It was found that the grinding caused an increase in surface
area and a grain size reduction of the samples. From TG and DTA results it
followed that grinding caused a decrease of the temperature at which the structure
bound OH groups released. The formation of high temperature phases was enhanced
with the ground samples. For the ground talc sample the crystallization of
non-crystalline phase into orthorhombic enstatite was observed in the range
of 800°C. For ground pyrophyllite a certain agglomeration of grains was
observed in the range above 950°C. Moreover, for both clays the ETA characterized
a closing up of subsurface irregularities caused by grinding as a decrease
of the emanation rate in the range 250–400°C. The comparison of
thermal analysis results with the results of other methods made it possible
to better understand the effect of grinding on the ceramic clays.
Authors:V. Balek, N. Todorova, C. Trapalis, V. Štengl, E. Večerníková, J. Šubrt, Z. Malek, and G. Kordas
Summary Titania-based photocatalytic materials were prepared by sol-gel method using Fe3+ and polyethyleneglycol (PEG600) as additives. Thermogravimetry (TG), differential thermal analysis (DTA) and evolved gas analysis (EGA) with MS detection were used to elucidate processes that take place during heating of Fe3+ containing titania gels. The microstructure development of the Fe2O3/TiO2 gel samples with and without PEG600 admixtures was characterized by emanation thermal analysis (ETA) under in situ heating in air. A mathematical model was used for the evaluation of ETA results. Surface area and porosity measurements of the samples dried at 120°C and the samples preheated for 1 h to 300 and 500°C were compared. From the XRD measurements it was confirmed that the crystallization of anatase took place after thermal heating up to 600°C.
Properties of limestone related to SO2/SO3 reactivity were investigated. Limestone calcined under different conditions (temperature, time and with/without additives)
yield calcines of distinctly different physical structures. The amount of pores and the size of the pores formed during calcination
The main purpose of the present work was to gain a better understanding and more reliable explanation of the temperature regime
for gas desulphurization using Ca-based sorbents in atmospheric fluidized-bed combustors.
Pore size, surface area and pore volume of each calcine were determined by mercury porosimetry and BET methods. At higher
calcination temperature and during longer time, sintering became significant and the obtained calcine had a smaller internal
surface area and thereby the average pore radius increased. The additives such as NaCl also accelerated sintering thus increasing
the pore size. The measurements of porosity were supplemented by scanning electron microscopic observations employed for qualitative
description of the pore structure. SEM micrographs are presented.
Authors:Xue-Gang Chen, Shuang-Shuang Lv, Ping-Ping Zhang, Lu Zhang, and Ying Ye
rice hull-based adsorbent and composites for water purification. Two major factors: the amount of adsorption sites associated with surfacearea and pore volume, and the adsorption force associated with pore size and chemical compositions, determine the
Authors:Lingli Peng, Xiangyu Xu, Zhi Lv, Jiaqing Song, Mingyuan He, Qian Wang, Lijun Yan, Yang Li, and Zhaofei Li
catalysts [ 4 , 5 ] in refining [ 6 – 12 ], petrochemicals and fine chemicals processes [ 13 ]. The usefulness of a specific alumina in each of these processes requires a favorable combination of textural properties, including surfacearea, pore volume, and
Authors:A. Usherov-Marshak, V. Sopov, and W. Kurdowski
The capillary porosity of clinker phases, i.e. 3CaOSiO2, β2CaOSiO2, 3CaOAl2O3 and 4CaOAl2O3Fe2O3, at the early stages of hydration has been studied by the methods of Differential Scanning Calorimetry and nitrogen adsorption
It was established that pores of 3–70 nm were formed during the hydration of 3CaOSiO2 and the maximum of their distribution was found at about 10 nm. The hydration of 2CaOSiO2 is much slower and the porosity is one order of magnitude lower. During the hydration of 3CaOAl2O3 the content of crystalline hexagonal hydrates prevailed and the porosity was in the range 5–90 nm with the average pore diameter
of about 16 nm. This average pore diameter was much smaller for thermoporosimetry and lay at about 7 nm. The hydrated 4CaOAl2O3Fe2O3 sample had the porosity in the range 3–90 nm with the maximum of the pores distribution at about 4 nm. There are some differences
between the porosities measured by BET and thermoporosimetry. Principally thermoporosimetry gives no information about larger
capillary pores in the range 30–50 nm.