3927968

Interpreting heterogeneous catalytic reaction mechanisms through relationships between adsorbate and near-surface gas phase compositions

Date
August 15, 2023
Explore related products in the following collection:

The investigation of chemical processes on surfaces at operating temperatures and pressures has yielded extraordinary insights into the role of adsorbates and the importance of specific active sites on heterogeneous catalytic reaction outcomes. However, there is mounting evidence that for many reactions, unique information on reaction pathways can be obtained through the additional study of chemical events in the near-surface gas phase – and that this information complements that obtained through use of surface-sensitive probes.

Here, we present results from recent investigations involving analysis of the gas phase above catalyst surfaces in operating conditions. In our work, the near-surface region (defined as a region hundreds of microns to millimeters above a surface) is interrogated through a novel combination of optical spectroscopy, Raman spectroscopy, and molecular-beam mass spectrometry with universal species detection capability. These techniques are supplemented by diffuse reflectance FTIR spectroscopy, which selectively probes adsorbate compositions during reactions. Efforts focus on understanding oxidative conversion of hydrocarbons and alcohols, which in relevant operating conditions can be influenced by chemical events occurring both on the surface and in the gas phase. The presented results primarily involve study of reactions over supported metal and metal alloy catalysts surfaces (eg, Ag, Pd, Pt, AuPd). This approach is also extended to include well-defined, site-isolated supported metal catalysts. In these materials, the metals are often atomically dispersed, with cationic character, with the local environments of metals analyzed through X-ray absorption spectroscopy. The ultimate goal of this research is to relate local composition/structure of well-defined active sites to the local gas-phase composition (including unstable or reactive species, such as radicals).

Related Products

Thumbnail for CATL Open Source Software Workshop A: Molecular Scale
CATL Open Source Software Workshop A: Molecular Scale
DIVISION/COMMITTEE: [CATL] Division of Catalysis Science & Technology
Thumbnail for Influence of CO2 on ethane dehydrogenation over chromium sites stabilized by highly siliceous MFI zeolite
Influence of CO2 on ethane dehydrogenation over chromium sites stabilized by highly siliceous MFI zeolite
Ethylene is one of the most important products of the chemical manufacturing industry. Its synthesis is gradually shifting from traditional steam cracking of petroleum feedstocks to catalytic dehydrogenation of ethane from natural gas…
Thumbnail for Synthesis and characterization of zeolite-supported platinum catalysts with controlled platinum nanoparticle locations
Synthesis and characterization of zeolite-supported platinum catalysts with controlled platinum nanoparticle locations
Pt/HZSM-5 is widely used in hydrocarbon conversion, undergoing cycles of operation under reductive conditions followed by regeneration to remove coke. The redox cycling leads to changes in the size and location of platinum nanoparticles in the catalysts…