Structural Changes of Bimetallic PdX/Cu (1-X) Nanocatalysts Developed for Nitrate Reduction of Drinking Water
- PDF / 623,325 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 161 Views
R4.8.1
Structural Changes of Bimetallic PdX/Cu (1-X) Nanocatalysts Developed for Nitrate Reduction of Drinking Water Huiping Xu1,2, Ray Twesten3, Kathryn Guy4, John Shapley4, Charles Werth5, Anatoly Frenkel6, Duane Johnson7 and Judith Yang1 1
Department of Materials Science and Engineering, University of Pittsburgh, Pittsburgh, PA 15261. 2 R.J.Lee Group, Inc., Monroeville, PA 15146 3 Center for Microscopy and Microanalysis, University of Illinois at Urbana-Champaign, Urbana, IL 61801. 4 Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801. 5 Department of Civil and Environmental Engineering, University of Illinois at UrbanaChampaign, Urbana, IL 618015. 6 Department of Physics, Yeshiva University, New York, NY 10016. 7 Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 618014. ABSTRACT Reductive removal by hydrogeneration using supported Pd/M (M= Cu, Pt, Ag, Co, Fe, Mo, Ni, Rh, Ir, Mn and Cr) bimetallic catalysts has emerged as a promising alternative for nitrate removal in drinking water [1]. Fundamental understanding how the atomic arrangement of Pd and a second element, such as Cu, affect the activity nitrite reduction and selectivity of dinitrogen will be accomplished by coordinated synthesis (Shapley), activity/selectivity/efficiency measurements (Werth) and nanostructure determination (Yang & Xu). In this paper, we report a systematic study of novel polyvinylpyrrolidone (PVP) stabilized nanoscale Pd-Cu colloids, with homogeneous and narrow size distribution, with Pd: Cu ratios varying from 50:50 to 90:10. Initial measurements on catalytic activity for nitrate reduction demonstrated a dependence on the relative composition. Electron microscopy studies, including Z-contrast imaging [2], energy-dispersive X-ray emission (EDX), electron diffraction and highresolution electron microscopy (HREM), revealed a surprising change in structure at the 80:20 Pd-Cu composition, where, with less than 80% Pd ,the nanoparticle forms a core-shell structure but for nanoparticles containing 80% or more Pd, it is homogeneous. We are at the pivotal point of directly correlating these nano-structures with the catalytic activity. Such an understanding is essential for the efficient development of catalysts for the purification of drinking water. INTRODUCTION Presently nitrate in drinking water is either not removed, or it is removed using ion exchange resins. The former presents health risks [3]; the latter is expensive because waste streams must still be treated when the resins are regenerated [4]. Nitrate is a stable and highly soluble ion with a low potential for co-precipitation or adsorption, so that removal of nitrates using conventional water treatment is difficult. An exciting and recently emerging approach involves hydrogenation of oxidized contaminants using supported bimetallic metal catalysts, such as Pd-Cu bimetallic catalysts [5-10]. However, these promising catalysts exhibit inadequate
R4.8.2
selectively toward nitrogen production,
Data Loading...
