In situ IR study for elucidating reaction mechanism of toluene steam reforming over Ni/La_0.7Sr_0.3AlO_3-δ catalyst

Steam reforming of toluene as a model compound of biomass tar was conducted on supported Ni catalysts. The Ni catalyst supported on perovskite oxide (La_0.7Sr_0.3AlO_3-δ: LSAO) showed the highest toluene conversion (58%) and lowest coke formation (57 mg g-cat ^-1) at 873 K thanks to the smaller Ni particle size and larger perimeter between Ni and perovskite support, confirmed by XRD, BET, STEM and XAFS. In this paper, adsorption of toluene on Ni/LSAO catalyst was investigated using FT-IR method to estimate the reaction mechanism. IR spectra during temperature programmed desorption revealed that strong adsorption of toluene was observed only on LSAO and Ni/LSAO. The decomposition of adsorbate to CO or CO₂ was promoted by supported Ni metal. Lattice oxygen of perovskite support contributed to the oxidation of the intermediate at the interface of Ni and perovskite. In addition, the oxidation of intermediate was promoted by introducing steam. Investigating adsorptions of various probe molecules (benzene, n-heptane, ethylene and benzaldeyde) revealed that decomposition of aromatic ring proceeded on Ni/LSAO.