Coupling of In Situ STEM-EDS and In Situ X-ray Absorption Spectroscopy for Bimetallic Industrial Catalysis

Event Sponsor: 
Integrated Imaging Initiative Seminar
Start Date: 
May 15 2017 - 4:00pm
Building/Room: 
Building 241/Room C-201
Location: 
Argonne National Laboratory
Speaker(s): 
Paul J. Dietrich
Speaker(s) Title: 
BP Group Technology

Catalysts are important materials in industrial chemistry that speed up chemical reactions and make the production of fuels, chemicals, and consumer products economically feasible.  Typically, academic catalysis studies use model materials under well-controlled conditions that are designed specifically for understanding the fundamentals of surfaces and chemistry.  However, most industrial catalysts are complex materials with varied nanostructures and non-ideal supports that operate under harsh, high pressure, high temperature environments that allow for productivity on a large commercial scale.  As the nanostructures are related to productivity, understanding and controlling the formation of the appropriate nanostructures and their stability under industrially relevant conditions is critical for the design and application of industrial catalysts. We have developed and implemented a state-of-the-art high pressure in situ STEM-EDS cell that allows for studies of the nanoscale structures of industrially-relevant materials under conditions more typical of their operating environments.  Here, we will detail a case study of in situ hydrogen activation of a bimetallic PdCu catalyst on a porous, irregular TiO2 support.  The nanostructure, particle size, elemental distribution and oxidation state of the constituent metals of this catalyst are all critical to its performance.  The evolution of the nanostructures and chemical information was tracked on both the nanoscale and bulk scale through a combination of STEM-EDS and X-ray absorption spectroscopy to achieve a more complete picture of the active catalyst state. We will detail the importance of this combined spectroscopy/microscopy approach and why it is relevant for studies of industrial-grade materials.