Surface protolysis reactions

The acidity constants for the surface protolysis reactions provide a measure of the extent to which the reaction will proceed. For the iron oxides the values of the pJC,s usually fall between 5 and 10, but there is considerable variation in the values for dif... 

Model Adjustable Parameters Protolysis Reaction Surface Complexation Reaction Surface Mass Balance... 

Spectroscopic data for Sr(II) were consistent with the selection of outer-sphere reactions to describe adsorption. Two outer-sphere reactions were employed to describe the trends in pH, ionic strength and surface coverage. One of the significant components of the modeling approach was that the TLM parameters used for Cd(II) and Sr(II) were constrained to employ the same model constants derived previously for Co(II). In both cases, it was possible to describe the adsorption behavior of these solutes using the same values of the surface hydroxyl site density, surface protolysis equilibrium constants, and electrolyte binding equilibrium constants. 

Volatile products derived from cracking PE with solid acid catalysts can be rationalized by carbenium ion mechanisms. Under steady-state conditions, hydrocarbon cracking processes that yield volatile prodncts can be represented by initiation, disproportionation, P-scission, and termination reactions [72, 73]. Initiation involves the protolysis of PE with Bronsted acid sites (H+ S ) to yield paraffins and surface carbenium ions ... 

For 2-methylpentane cracking the assumed reaction mechanism was based on that proposed by Zhao et al [8], Reactions are initiated by adsorption of 2-methylpentane feed on to Bronsted acid sites. Subsequent protolysis produces a carbenium ion on the surface of the catalyst (an adsorbed olefin) and a smaller gas phase paraffin molecule. Propagation reactions can then occur by hydride transfer between carbenium ions on the surface of the catalyst and gas phase feed molecules. Zhao experimentally determined certain bimolecular reactions to be more significant than others, the most significant were implemented in our model. Reactions are terminated by desorption of carbenium ions to yield a gas phase olefin molecule... 

Fig. 4.7 Scheme of the processes while phase transferring. Indices oo far from interface, 0 beginning of diffusion layer, ads outer surface, aq inner surface and aqueous phase, diss -dissolved, prot - protolyzed form, k reactions rate coefficients in gas phase (g), at surface ads) and in aqueous phase aq). Dg diffusion coefficient gas phase, sorption equilibrium coefficient, Dag diffusion coefficient aqueous phase, Kag equilibrium coefficient of protolysis, H Henry coefficent, Hgff effective Henry coefficient, a accommodation coefficient, /uptake coefficient. 

Figure 6.9. Periodic trends in the reaction energy for the protolysis of water to form surface-adsorbed hydroxyl intermediates and hydronium ions in solution.

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