262564 In Situ FTIR Identification of the Reactive Sites of a Ni/TiO2 Steam Reforming Catalyst

Thursday, November 1, 2012: 8:50 AM
317 (Convention Center )
Yishan Zhang1, Juan Cruz1, John Rabalais2 and Tracy J. Benson1, (1)Chemical Engineering, Lamar University, Beaumont, TX, (2)Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX

CO2 accumulation in the atmosphere, which is a major concern in global warming, has caught more and more attention all over the world. Tri-reforming is one of the potential processes for CO2 mitigation, which reacts steam methane reforming (SMR) effluents with natural gas and O2 to produce syngas (CO and H2).  Industrial SMR catalysts contain nickel supported on metal oxide, such as TiO2, MgO, CeO2, ZrO2, or a combination of them.  It is generally thought that Ni is responsible for the dissociation of H atoms while CO2 is activated on the oxygen vacancy support to form CO and O atom. However, little is known about the different surface species within the support for oxygen dissociation from CO2 at reaction conditions.

The synergistic interaction between the support and metallic sites responsible for the adsorption of CO and CO2 has been investigated in our work.  Ni/TiO2, which was synthesized by incipient wetness, was the selected catalyst, since TiO2 has an abundance of oxygen vacancies within its lattice structure.  These oxygen vacancies lend themselves to accept donor oxygen atoms from CO2, H2O, or O2In situ FTIR was used to investigate surfacing reacting species while using CO and CO2 as probe molecules.  The in situ reactor was temperature programmed (25 - 350°C) at 3°C/min while taking IR spectra throughout the temperature range.  The results indicate a multiplicative of reacting surface species (including lattice TiO2 lattice vibrations, Ti3+ and Ti4+) that can form at elevated reaction temperature conditions. This dynamic behavior explains the oxygen transport reaction mechanism necessary for tri-reforming reactions. In addition, a surface site mechanism has been proposed and is supported by reaction coordinate calculations.

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See more of this Session: In Situ and Operando Spectroscopy of Catalysts I
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