Hydrotalcite-like compounds

Ding, Y., Xu, L., Chen, C., Shen, X. and Suib, S.L. (2008) Syntheses of nanostructures of cobalt hydrotalcite like compounds and Co304 via a microwave-assisted reflux method. Journal of Physical Chemistry C, 112, 8177-8183. 

Table 1. Chemical composition of the fresh hydrotalcite-like compounds.

Table 2. Results of self-condensation of acetone over various calcined hydrotalcite-like compounds.

Abdelouas, A., Crovisier, J. L., Lutze, W., Fritz, B., Mosser, A. Muller R. 1994. Formation of hydrotalcite-like compounds during R7T7 nuclear waste glass and basaltic glass alteration. Clays and Clay Minerals, 42, 526-533. 

In previous papers, we reported surfactant adsorption onto hydrotalcite-like compounds, i.e. Mg-AI-C03-LDHs [10, 11]. We showed that LDH efficiency in removing anionic surfactant from aqueous solution by adsorption was greater than that of alumina. We also showed that it is possible to use LDH in the calcined form to remove surfactants from aqueous solution, which in turn involves two processes, intercalation by regeneration of the LDH structure and adsorption on the regenerated material. The whole surfactant removal process is designed in this case as sorption. These results emphasised the recyclability of LDHs and their potential use as surfactant removers. 

Structural and textural properties of zinc(II)-chromium(III) spinel oxides prepared using a hydrotalcite-like compound... 

The PXRD patterns for both the LDH and MH are shown in Figure 1. The LDH showed a PXRD pattern with very intense and sharp peaks, characteristic of a very well ordered hydrotalcite-like compound. The basal spacing obtained was 7.68 A, very close to the reported data [17,20,21] for carbonate containing LDH. From the chemical analysis we obtain the following molecular formula Zn2 9Cr(OH)7 8(C03)o5-2,3H20 (normalized to Cr = 1). The Zn Cr ratio obtained, 2.9, was slightly lower than the one expected, 3, indicating a preferential solubilisation of Zn(II) cations, a feature widely reported in the synthesis of LDHs [11]. 

New developments in the use of silicates to improve flame retardancy have arisen from the use of synthetic anionic clays that correspond to the family of lamellar mixed metal hydroxides, commonly named layered double hydroxides (LDH) or hydrotalcite-like compounds.17... 

Miyata, S. (1983). Anion-exchange properties of hydrotalcite-like compounds. 

Sato, T., Fujita, H., Endo, T., Shimada, M. and Tsunashima, A. (1988). Synthesis of hydrotalcite-like compounds and their physicochemical properties. React. Solids 5, 219. 

Costantino, U., Marmottini, F., Nocchetti, M. and Vivani, R. (1998). New synthetic routes to hydrotalcite-like compounds - characterisation and properties of the obtained materials. Eur. J. Inorg. Chem., 1439. 

Rives, V., Labajos, F. M., Ulibarri, M. A. and Malet, R (1993). Anew hydrotalcite-like compound containing V3+ ions in the layers. Inorg. Chem. 32, 5000. 

New hydrotalcite-like compounds containing yttrium. Chem. Mater. 9, 312. 

Miyata, S. and Kumura, T. (1973). Synthesis of new hydrotalcite-like compounds and their physico-chemical properties. Chem. Lett., 843. 

Ikeda, T., Amoh, H. and Yasunaga, T. (1984). Stereoselective exchange kinetics of L-histidine and D-histidine for Cl- in the interlayer of a hydrotalcite-like compound by the chemical relaxation method. J. Am. Chem. Soc. 106, 5772. 

Hibino, T. and Tsunashima, A. (1997). Formation of spinel from a hydrotalcite-like compound at low temperature reaction between edges of crystallites. Clays Clay Miner. 45, 842. 

Hibino, T. (1995). Decarbonation behavior of Mg-Al-C03 hydrotalcite-like compounds during heat treatment. Clays Clay Miner. 43, 427. 

Dumitriu, E., Hulea, V., Chelaru, C., Catrinescu, C., Tichit, D. and Durand, R. (1999). Influence of the acid-base properties of solid catalysts derived from hydrotalcite-like compounds on the condensation of formaldehyde and acetaldehyde. Appl. Catal. A 178, 145. 

Kannan, S. (1998). Decomposition of nitrous oxide over the catalysts derived from hydrotalcite-like compounds. Appl. Clay Sci. 13, 347. 

Perez Ramirez, J., Overeijnder, J., Kapteijn, F. and Moulijn, J. A. (1999). Structural promotion and stabilizing effect of Mg in the catalytic decomposition of nitrous oxide over calcined hydrotalcite-like compounds. 

Oi, J., Obuchi, A., Ogata, A., Bamwenda, G. R., Tanaka, R., Hibino, T. and Kushiyama, S. (1997). Zn, Al, Rh-mixed oxides derived from hydrotalcite-like compound and their catalytic properties for N20 decomposition. Appl. Catal. B 13, 197. 

Ulibarri, M. A., Pavlovic, I., Hermosin, M. C. and Cornejo, J. (1995). Hydrotalcite-like compounds as potential sorbents of phenols from water. 

Yong Z., Meta V. and Rodrigues A E., Adsorption of carbon dioxide onto hydrotalcite-like compounds (HTis) at high temperatures. Ind. Eng. Chem. Res. 40 (2001) pp. 204-209. 

Layered double hydroxides (LDHs) are a unique type of clay with anion exchange capacity. In nature, they are found in the carbonated hydrotalcite-like compounds... 

Physical sorbents for carbon dioxide separation and removal were extensively studied by industrial gas companies. Zeolite 13X, activated alumina, and their improved versions are typically used for removing carbon dioxide and moisture from air in either a TSA or a PSA process. The sorption temperatures for these applications are usually close to ambient temperature. There are a few studies on adsorption of carbon dioxide at high temperatures. The carbon dioxide adsorption isotherms on two commercial sorbents hydrotalcite-like compounds, EXM911 and activated alumina made by LaRoche Industries, are displayed in Fig. 8.F23,i24] shown in Fig. 8, LaRoche activated alumina has a higher carbon dioxide capacity than the EXM911 at 300° C. However, the adsorption capacities on both sorbents are too low for any practical applications in carbon dioxide sorption at high temperature. Conventional physical sorbents are basically not effective for carbon dioxide capture at flue gas temperature (> 400°C). There is a need to develop effective sorbents that can adsorb carbon dioxide at flue gas temperature to significantly reduce the gas volume to be treated for carbon sequestration. 

Fig. 8 Adsorption isotherms of carbon dioxide on commercial sorbents. (A) Hydrotalcite-like compound, EXM911 (B) LaRoche Industries activated alumina at 20, 200, and 300°C. (From Refs. -i l)...

Scavetta, E., Berrettoni, M., Nobili, F., and Tonelli, D. 2005. Electrochemical characterisation of electrodes modified with a Co/Al hydrotalcite-like compound. Electrochimica Acta 50, 3305-3311. 

Jiao, Y.N. and Hou, W.G.. Effects of structural charges on points of zero charge and intrinsic siuface reaction equilibrium constants of Zn-Al and Zn-Al-Fe hydrotalcite-like compounds. Colloids Surf. A, 296, 62, 2007. 

Hou, W.-G. et al.. Studies on zero point of charge and permanent charge density of Mg-Fe hydrotalcite-like compounds. Langmuir, 17, 1885, 2001. 

Hou, W.-G. and Ren, C., Evaluation of intrinsic ionization and complexation constants of TiO2 and Mg-Fe hydrotalcite-like compounds. Chinese J. Chem., 24, 1336,... 

Li, D.X. et al., The isoelectric points and the points of zero charge of Fe-Al-Mg hydrotalcite-like compounds, Chinese Chem. Lett., 15, 224, 2004. 

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