Alkaline hydroxide activation precursors

From this example of space cryocoolers, as well as previous examples of other applications, the importance of the development of narrow microporosity during the preparation of AC has been demonstrated. In this chapter, the way to tailor this type of porosity has been shown this is by chemical alkaline hydroxide activation of carbon precursors with careful control and thorough understanding of the variables affecting the carbon activation process. 

During the last 15 years our group has been researching carbon activation by alkaline hydroxides, analyzing its different aspects. Thus, we have compared both NaOH and KOH with other chemical agents [23], we have analyzed several variables of this activation process [21,23,42,43,70-72,77,88,98], we have studied the reactions taking place [99-101], we have worked on their porosity characterization [12,13,70,102-106], and, finally, we have studied these ACs in several applications [71,107-114]. From all these studies, which cover most of the aspects of carbon activation by alkaline hydroxides, we have been able to identify additional advantages to those mentioned earlier (1) the precursor ash content has no... 

As discussed in Section I, in this chapter we strive to simplify the study of reactions occurring during chemical activation with alkaline hydroxides by limiting our analysis to the activation of carbon materials. In other words, carbonaceous precursors that are not carbons are excluded. To identify the reaction products, to understand the types of reactions occurring, and to propose a main global reaction for hydroxide activation, a combination of different techniques has been used FTIR, in situ XRD, analysis of activation products followed by mass spectrometry, as well as thermodynamic data [99-101]. 

The most general methodology followed to prepare alkaline earth metal oxides as basic catalysts consists of the thermal decomposition of the corresponding hydroxides or carbonates in air or under vacuum. BaO and SrO are prepared from the corresponding carbonates as precursor salts, whereas decomposition of hydroxides is frequently used to prepare MgO and CaO. Preparation of alkaline earth metal oxides with high surface areas is especially important when the oxide will be used as a basic catalyst, because the catalytic activity will depend on the number and strength of the basic sites accessible to the reactant molecules, which is dependent on the accessible surface area. 

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