Primary pore structure analysis

Cases 3-D sizes [nm X nm x nm] Number of component units in different cases  

Cases Solvents Symbol Dielectric permittivity Agglomerate size [nm ]  

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Wozniak, R. W., Bartnik, E., and Blobel, G. (1989). Primary structure analysis of an integral membrane glycoprotein of the nuclear pore. J. Cell BioL 108,2083-2092... 

To confirm that the sphericai silica gei comprises of primary nanogeis, the pore structure was analyzed by the BET analysis. Contrary to the expectations, the precursor and aged silica gels have relatively very low specific surftice area. In Table I, the specific surface area of the precursor and aged silica gels was presented. As the addition amount of MH3 increased, the specific surface area increased. 

The water in coal is bound in different forms to its constituents. It can be divided into three types (1) Free moisture, also referred to as external moisture, superficial moisture, or the primary moisture fraction, which is present in large cracks and capillaries. Water bound in this way retains its normal physical properties. (2) Inherent moisture, also referred to as internal moisture or the secondary moisture fraction, whose vapor pressure is lower, since it is absorbed within the pore structure of the coal. (3) Water of constitution, which is mainly combined with mineral matter normally present in coal. This water is generally driven off only at temperatures higher than those normally used for the determination of moisture content. Standard methods do not make use of these terms and define (1) the total moisture content of a coal and (2) the moisture content of the coal analysis sample. Total moisture determination must be made over the sample as received in the laboratory, in an air-proof recipient. The determination consists in drying in an oven at 105 °C till constant weight. Its value is of huge interest both in international and domestic coal trade (ISO 589, ASTM D3173). 

The approaches considered allow modeling of the primary texture of PS and the processes, limited by individual PBUs that mainly correspond to level III and partially to level IV in the hierarchical system of models (see Section 9.6.3). PBUs are identical in regular PSs, and simulation of numerous processes may be reduced to analysis of a process in a single PBU/C or PBU/P. An accurate modeling of the processes in irregular PSs requires the studies of the properties of structure and properties of the ensembles (clusters) of particles and pores (level IV of the system of models) and the lattices of such clusters (levels V to VII of the system of models). Let us consider the composition of clusters on the basis of fractal [127], and the lattices on the basis of percolation [8] theories. 

An analysis of the anode showed that the structure was only 62.9% flooded. The electrolyte which was wetting the pores of the electrode had an approximate composition of 4.8 mole% sulfide and 95.2 mole% carbonate. Examination of the electrode material under x-ray diffraction shows that the primary species are Ni and NiO, with a small amount of Ni,S, present also. X-ray diffraction data is presented in Figure 13. 

Among the characterization techniques, the primary one is particle X-ray diffraction (PXRD) analysis, which is essential to determine if the material retained the crystal structure following the postmodification steps. Nevertheless, this technique suffers from the inability to detect amorphous by-products, if any, and by the sometimes weak response due to the presence of crystalline impurities and/or structural distortions [85]. Measurement of the BET surface area gives evidence whether species, Unked or not, are trapped inside the pores and the accessible volume is reduced. In addition, elemental analysis of the modified MOFs is essential to determine the exact formula of the material. However, the framework often contains an undetermined number of solvent molecules that could lead to difficulty in interpreting the data. 

So, the ethylene production does correlate with coke presence, in particular with aromatics formation as far as the diffusion limitations are not significant. However, it seems that the majority of ethylene is not always formed directly from MeOH [115]. The aromatics and other coke species could be the products of the conversion of primary carbenium ions, which are mobile and could equilibrate each other [28]. This may explain the isotopic distribution in products and retained coke molecules and the coexistence of aromatics and carbenium ions [28], In addition to the coproduction of ethylene with aromatics in olefins interconversion cycle, formation of ethylene via alkylation-dealkylation of methyl aromatics with heavy olefins or with the equivalent carbenium ions like ethyP, propyP, and butyP could be an option. The alkyl aromatics with the side chain length of two carbons or longer are not stable in the pore and dealkylates on the acid sites due to too long residence time and steric hindrances. This may lead to formation of ethylene, other olefins, and alkylaromatics with different structure, namely PMBs [129]. In other words, the ethylene is formed via interaction of the carbenium ions like ethyP, propyP, and butyP formed from MeOH or heavy olefins with aromatics and other coke precursors followed by cracking and in a less extent by a direct alkylation of PMBs with methanol. The speculation is based properly on analysis of the prior arts and is not contradictory with the concept of the aromatic cycle for ethylene formation. 

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