389 Investigation of Non-Thermal RF Plasma Effects On the Surface Properties of TiO2 Supported Pd Catalysts

Friday, November 6, 2009: 9:00 AM
Charolais (Camino Real Hotel)
Yanan Li , Department of Chemistry, Texas A&M University-Commerce, Commerce, TX
Ben W.-L. Jang , Department of Chemistry, Texas A&M University-Commerce, Commerce, TX
Non-thermal plasma treatment has unique modification effects on supported metal catalysts. The unusual property of hydrogen and argon plasmas is that they can reduce the supported metal precursor while oxygen plasma could oxidize and reduce metal precursor simultaneously. TiO2 supported Pd(NO3)2 catalysts were modified by different plasma treatments, including hydrogen, argon and oxygen plasmas, at room temperature and were compared to the catalysts with conventional reduction and calcination procedures. Both XPS and DSC analyses confirm that hydrogen and argon plasma treatments can reduce Pd2+ effectively. The DSC in hydrogen atmosphere (H2-DSC) has been identified as a very sensitive technique for the measurement of small quantity of supported PdO and Pd(NO3)2 via heat involved during hydrogenation.
  Oxygen plasma can possibly replace the thermal calcination procedure and avoid the abrupt decrease of Pd dispersion induced by high calcination temperature such as 500°C. H2 chemisorption results show that Pd dispersion of 1wt%Pd/TiO2 increases with oxygen plasma treatment time. In addition, oxygen plasma treatment is more efficient than calcination in changing the interaction between TiO2 and Pd species. The interaction has been quantified by reduction temperature of PdO and Pd(NO3)2 during DSC. It demonstrates that non-thermal plasma is an effective way to manipulate surface properties and to design supported catalysts with unique metal-/metal precursor-support interaction.