Studies on certain physical properties of modified smectite nanocatalysts

Most volatile organic compounds (VOCs) are toxic to humans in some manner. Generally, transitional metal catalysts have better conversion rates for controlling VOCs. However, catalyst activity will decay at high temperature, though the oxidizing catalyst is cheap. This study used smectite as the carrier to exchange with Ag+, Zn2+ and Ti4+ to modify the surface and form smectite catalysts. In addition, the transmission electron microscopy (TEM), FT-IR spectrum, and DSC-TGA instrument were applied to characterize their physical properties. After the FT-IR analysis of the modified smectite catalyst (smectite-Ag, smectite-Zn and smectite-Ti), both smectite and smectite catalyst had significant and complicated wave crests between the fingerprint area with the wave numbers of 415-600cm(-1) and 750-1170cm(-1), that indicated the existence of a strong bond between impure silicates (Si-O) and silicates (O-Si-O). TEM observation proved that sintering at 350 degrees C results in the distribution of catalyst ions on clay carrier with a nanoscale. As thermal analysis reveals, the smectite reached endothermic peaks at the temperatures of 920 degrees C and 1057 degrees C, respectively, and shows the decomposition in a non-crystal form. Besides, the disappearance of the endothermic peak of smectite-Ag occurs at 920.5 degrees C and the exothermic peak occurs at 950 degrees C. The results indicating crystals formed of smectite-Ag are more comprehensive and stable than the other smectite or modified smectite catalysts at high temperature. (C) 2011 Elsevier B. V. All rights reserved.