China
Africa
Explore chapters and articles related to this topic
Microporous and Mesoporous Solids
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Elaine A. Moore, Lesley E. Smart
Sodalite is a good example of a small-pore zeolite. A cavity in sodalite (the β-cage) is bounded by a 4-ring with a diameter of 260 pm (Figure 7.5); although this is a very small opening, it can admit water molecules and can be used to dry gas streams.
Solid-State NMR Studies of Zeolites and Related Systems
Published in Alexis T. Bell, Alexander Pines, NMR Techniques in Catalysis, 2020
C. A. Fyfe, Κ. T. Mueller, G. T. Kokotailo
Figures 1d and e show two other zeolites made up from the same basic building block. When two units share a four-membered ring (Fig. 1d), the sodalite lattice is formed. In this case the structure is completely space filling (the central cavity being identical to the building unit), and this system shows no catalytic or molecular sieving properties. As opposed to zeolite A, sodalite occurs naturally. Figure le shows the lattice structure of faujasite, a very rare mineral species, whose synthetic counterpart is known as zeolite X or zeolite Y (depending on the Si/Al ratio). The synthetic versions are widely used in petroleum refining. There is again a large central cavity, but in this case the channels are no longer straight. There are four openings to each large cavity, giving a three-dimensional channel system.
Other Phases of Matter
Published in Mary Anne White, Physical Properties of Materials, 2018
Figure 11.8 shows two zeolite structures, sodalite and zeolite A, that can be considered in terms of building on the four-membered rings on the sodalite cage. Another zeolitic form could be built up by adding hexagonal prisms onto the six-membered rings on the sodalite cage and then adding another sodalite cage at the end of the hexagonal prisms. This mechanism forms the zeolite known as faujasite. How would you expect faujasite to differ from sodalite and zeolite A in terms of the molecules that can be included inside the structure? Explain.
Modified zeolite from metakaolin and fly ash as efficient adsorbent for cationic methylene blue dye removal
Published in Chemical Engineering Communications, 2023
Naruemon Setthaya, Kedsarin Pimraksa, Nattapong Damrongwiriyanupap, Dimitrios Panias, Pagasukon Mekrattanachai, Chakkresit Chindawong
The XRD patterns of the TiO2-containing zeolite with an MK-to-FA weight ratio of 4:1, shown in Figure 3, reveal that the zeolite type changed when the zeolite was combined with TiO2. Some of the zeolite A of the starting material was transformed to sodalite; therefore, the main phases of the TiO2-containing zeolite were sodalite and zeolite A. The high temperature during the calcination step likely had a considerable effect on the zeolite phase transformation. The zeolite A crystallization process resulted in a decrease in density, whereas the sodalite nucleated with a higher density than that of zeolite A, in accordance with the findings of Greer et al. (2009). The high temperature induced a zeolite phase transformation from low to high density. However, the XRD results reveal that zeolite A and sodalite peaks appeared inside the zeolite synthesized with an MK-to-FA weight ratio of 4:1 (Figure 3a); thus, calcination of the TiO2-containing zeolite at 500 °C (Figure 3b,c) led to the growth of sodalite crystals and destruction of zeolite A crystals. Finally, the zeolite A crystals were consumed through an Ostwald ripening process (Greer et al. 2009; Rios et al. 2009).
Substrates and preparation layers under the wall paintings of the St George’s Cathedral (1119 CE) at Veliki Novgorod
Published in Surface Engineering, 2023
Alessandra R. G. Giumlia-Mair, Vladimir V. Sedov, Olga Etinhof
The SEM-EDS analysis of a twelfth century fragment sample with a blue colour (Figure 14) showed instead that under the actual blue pigment, consisting of lazurite i.e. ground lapis lazuli, a layer of greyish-blue clay was used on top of the reft layer (Figure 15), a technique very different from the one just described above that was employed in later times. Lazurite was the most expensive pigment, both in antiquity and until today, because not many deposits of lapis lazuli are known, and this mineral is also used as precious stone. The underpaint with blue clay improved the coverage, deepened the colour, and helped to economise because a lesser quantity of the expensive lazurite pigment could be employed. The SEM examination showed that the blue lazurite was applied on blue clay, which was itself applied on a layer of reft. The intonachino and intonaco are the well refined, very white plaster mixtures with only straw and a very small amount of sand, known from the twelfth century. The EDS analysis showed the typical lazurite peaks and following results: Na2O 9.7; MgO 1.8; Al2O3 19.3; SiO2 30.8; SO3 7.4; Cl2O 0.6; K2O 2.8; CaO 21.8; Fe2O3 5.3. The EDS analysis of granules present in the lazurite identified some sodalite, tourmaline and phlogopites, which are typical components of lazurite.
Material balance evaluation of pyroprocessing for minor actinide transmutation nitride fuel
Published in Journal of Nuclear Science and Technology, 2020
Haruka Tateno, Takumi Sato, Yasuhiro Tsubata, Hirokazu Hayashi
The salt-loaded zeolite must be immobilized for disposal in a geological repository. A glass-bonded sodalite has been proposed as the final waste form of spent zeolite [38]. A low capacity of chlorides in the glass matrix requires the sodalite to completely incorporate the chlorides. Transforming the salt-loaded zeolite 4A to sodalite produces free chlorides, because the chloride capacity of sodalite is much smaller than that of zeolite 4A. Only up to 3.8 Cl− ions per unit cell of zeolite 4A is acceptable [39], while the salt-loaded zeolite 4A will often contain 15 Cl− ions per unit cell. Therefore, in the waste form process, the salt-loaded zeolite is mixed with a large amount of fresh zeolite, and is then heated to produce sodalite. The borosilicate glass, which constitutes 25% of the total mass, is added to produce the final glass-bonded sodalite waste form [40].