Montmorillonites modified with carbonaceous deposits - I. Formation mechanism and acidity

The mechanism of-formation of carbonaceous deposits on montmorillonites was studied for systems prepared by sorption of polymers on pillared-montmoril lonites and subsequent carbonization. Temperature-programmed desorption of ammonia and X-ray photoelectron spectroscopy showed that polymer was attach ed to Al-OH acidic sites of smectite layers. Pillars were not influenced to a greater extent. Islands of carbonaceous material were formed, but the am ount of deposited carbon depended strongly upon carbonization conditions. T he hydrophylic and acidic properties of carbon-covered silica aluminas diff ered strongly from those of the Starting material. (C) 2000 Academic Press.