Adsorbed layer, organic transformations

If the catalyst is in the same phase as the reactant (e.g., dissolved metals catalyzing transformation of dissolved organic substances), the catalysis is called homogeneous. When the catalytic process is determined by a catalyst in a different phase than the reactant (e.g., solid metal oxides catalyzing transformation of dissolved organic or inorganic substances), the catalysis is called heterogeneous. In this case, the catalyzed reaction steps occur very close to the solid surface the reactions may be between the molecules adsorbed on the catalyst surface or may involve the top-most atomic layer of the catalyst. 

Among all layered silicate clays, the smectite family of 2 1 layer lattice structures are preeminent in their ability to adsorb organic molecules and to catalyze their chemical transformations. All metal oxides in the soil environment may exhibit some degree of surface reactivity. However, the adsorptivity and reactivity of typical smectites are facilitated by their relatively high internal surface areas 700 m2/g) and external surface areas (10-50 m2/g). 

The features of the adsorbed complex of the Cambrian argillites were intensely transformed by diagenetic reactions, making them unsuitable for any interpretations. The complex composition of the clays which consist of kaolinite, illite, chlorite and mixed-layer minerals, together with the absence of organic matter leads to the conclusion that the areas of denudation must have been of a local nature. At the same time, we may reconstruct a temperate to humid climate interrupted at times by periods of relative aridity. This explains the lack of laterites on the eruptive and metamorphic rocks. 

The formation and transformation of electroinactive 2D condensed organic mono-layers adsorbed at the electrode-electrolyte interface are predominantly controlled by electrocapiUary forces and yield [16], instead of Eq. (11) ... 

The general picture given here applies only to the simplest kinds of molecules. Often other factors, in particular steric effects, influence the adsorption behavior of organic molecules. In that case, there is no simple correlation between the electron density at the functional group and the inhibition efficiency. The same is true if the inhibitor forms surface films of more fhan one atomic layer, or if it undergoes an oxidation or reduction reaction at the surface. An even more complicated situation arises if the inhibitor undergoes a chemical transformation and the reaction product adsorbs on the metal, a mechanism referred to as secondary inhibition. 

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