*2.6.1. Systems lamellar characterizations*

*2.5.2. Hexacyano-cobaltates synthesis (porous materials)*

54 Advances in Petrochemicals

**Figure 7.** Hexacyano-cobaltates synthesis.

**2.6. Characterization techniques**

finally the material is air-dried to constant weight.

The amount in excess of the metals involved guarantees the formation of a single phase. The resulting precipitate remains for a week in the mixture. Then it is separated by centrifugation. The solid fraction is repeatedly washed with distilled water to remove the excess ions, and

To ensure that the phases that have been obtained during the synthesis are correct, various techniques are used. This chapter will talk about three of them, which allude to the obtaining of the phases. One of them is X-ray diffraction (XRD), which is used under two aspects: to get the diffraction patterns of the synthesized material and to ensure that the crystalline phases of the structures meet the required specifications, which includes synthesis. On the other hand, this technique is used to perform a constant monitoring during the dehydration of materials and thus observe the structural change to drop out of the same water molecules present in the

Figure 7 shows the hexacyano-cobaltates synthesis process.

The family of tetracyano-niquelates (M (H2O) 2 [Ni (CN) 4] ⋅xH2O); M: Mn, Co and Ni, x = 1, 2, and 4 has been studied recently due to its ability to store molecules such as H2, CO2, and N2. It is known that they crystallize in three different ways, that is, phase L1, phase K, and phase L0 [7]. The forms adopted due to the water molecules present in the structure and their interaction with metals assemblers. Figure 8 shows three phases reported.

**Figure 8.** Framework for L1 (a), K (b), and L0 (c) phases. Coordinated water molecules from neighboring layers re‐ mains linked through aquo-bridges (hydrogen bonding interactions).

Thermal analysis is performed in four aspects: (i) analyze how to change kinetic parameters in a same phase for different metals of assembly, (ii) observe the influence of kinetic parameters over the same metal assembly on three different stages, (iii) analyze L0 to L1 phase change during the process of dehydration, and (iv) vary kinetic parameters as the partial pressure of water in the system is changed. All materials are needed to monitor the process of dehydration with the help of XRD to observe when there is a change in the structure or collapse once the material molecules are removed totally or partially.
