Catalysis of radical decomposition of hydroperoxides on the surface of modified montmorillonite

Abstract

4 Hydroxy 3 methyl 4' benzeneazo(azobenzene) is used as an inhibitor to study the kinetics of radical generation upon cumyl hydroperoxide or tert butyl hydroperoxide decomposition in microemulsions formed in the presence of cationic surfactants in organic solvents and on the surface of montmorillonite par ticles modified with cationic surfactants. It is demonstrated that, in contrast to microemulsions, at compara ble surfactant contents, modified montmorillonite has almost no effect on the decomposition rate of hydro peroxides. A considerable catalytic effect is only detected after Cu(2+) ions (≤0.1 wt %) are additionally applied onto the surface of its nanoparticles. The addition of polar solvents dramatically decelerates the decomposition of hydroperoxides. The activation energies of the reaction are determined for the dispersions of modified montmorillonite in toluene (56 kJ/mol) and toluene-ethanol mixture (69 kJ/mol).

Spectral and photochemical properties of tetraphenylporphyrin tetrasulfonate supported on modified montmorillonite nanoparticles

“…As noted in [5,6], a fairly high transparency of MMCS dispersions with a deposited catalyst in the near UV and visible range makes it possible to analyze the processes involving them using the spectrophoto metric technique. In this case, the ATPPS/MMCS spectral features can be quantitatively characterized.…”

“…In this case, the nanoparticle provides com bination of the thermodynamically incompatible catalytic center with the substrate at the molecular level or close to it, and at the same time allows easy separation of the catalyst from the reaction products. This method, for example, was used to fabricate nano catalysts on the basis of montmorillonite modified with a cationic surfactant (MMCS) [5,6]. These nanocatalysts containing copper [5] or other metal salts or phthalocyanines [6] as an active component exhibit high activity in toluene and other organic sol vents, in which the copper salts or phthalocyanines are insoluble.…”