Preparation of the Reactive Silica RSi Samples

Morterra and Low [14,15] have demonstrated that the methoxy groups (=Si-OCH3) can be fully substituted for the surface hydroxyl groups (=Si-OH) after treating silica surface in a methanol vapor at 700 K. They found that, upon the subsequent high-temperature pyrolysis of such samples (T 1050 K), a series of chemical reactions proceed, with the following key reaction  

The structure of the centers responsible for the chemisorptions activity of the RSi samples is analyzed in Refs. [18,19] and is discussed in detail in the next sections of this chapter. 

The use of the molecules of other (ethyl and heavier) alcohols with this object allows the replacement of the surface hydroxyl groups by the alcohol groups, although the pyrolysis of the latter does not remove oxygen atom. For the groups with a more complicated structure, new transformation channels arise with a higher transformation rate. For example, the thermal decomposition of the surface ethoxy groups follows the scheme 

Structure and Concentration of Paramagnetic and Diamagnetic Point Defects on Activated Silica Surface 

The structures and concentrations of paramagnetic and diamagnetic sites on the surface of TSi, MSi, and thermo chemically activated (RSi) silica is presented in Table 7.1. The data for the RSi sample subjected to the thermo oxidative treatment (see Section 11.3), resulting in an increase in the 

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