Description:

Thursday November 14, 2019
Albert Gili de Villasante, Technical University Berlin, Materials Science and Technology - Ceramic materials

Title: In situ XRD of a nickel supported catalyst using synchrotron radiation: implications for the dry reforming of methane and for carbon nanotubes growth by chemical vapor deposition.

Abstract: application of in situ x-Ray diffraction using synchrotron radiation has been done to a 5%Ni/MnO catalyst during dry reforming of methane under different reaction conditions. Combination with catalytic tests in a fixed-bed plug-flow reactor enabled to identify the deactivation mechanisms, optimize reaction conditions and suggest the mechanism of reaction on this catalyst. Expansion and contraction of the nickel lattice parameter upon interaction with methane reveals the growth mechanism of multiwalled carbon nanotubes during the chemical vapour deposition process. To accept carbon into the octahedral interstitials of the cubic nickel nanoparticles, the lattice needs to expand. This expansion continues to occur until the limit of solubility of carbon in nickel is achieved: subsequently, the lattice contracts due to the precipitation of graphitic nanotubes. The still expanded lattice of nickel after precipitation points to the dominance of surface diffusion as the main mechanism of carbon transport, supported by DFT and NEB calculations. These observations and the elucidation of the growth mechanism has strong implications for the dry reforming of methane process.

The Center for Catalysis and Surface Science (CCSS) is a strategic research center within the Institute for Sustainability and Energy at Northwestern (ISEN). CCSS promotes interdisciplinary research fundamental to the discovery and atomistically-controlled synthesis of catalysts that optimize the sustainability of industrial and consumer goods.