Despite tremendous potential to transform manufacturing, conversion of light hydrocarbons, especially methane, to value-added products faces both kinetic and thermodynamic challenges. Since conventional gas-to-liquid (GTL) technologies encounter economy-of-scale issues at emerging sources of light hydrocarbon gases, new technologies are needed. Our group has achieved enhanced methane conversion performances by modifying a typical methane reforming (Ni-Mg/(Ce0.6Zr0.4)O2) catalyst by two methods. First, a zeolite shell was layered around the reforming catalyst core to achieve size selective steam reforming of various size hydrocarbons. In addition to improved stability due to blocking of large aromatics that are known to cause carbon deposition, increased activity was also surprisingly obtained for thin shells. When the shell thickness increased, methane conversion decreased due to mass transfer limitations. A number of control experiments with various layered catalysts and physical mixtures of components indicated that both the presence of Al and microporous structure of the zeolite were integral to the enhanced activity. Second, very low loadings (0.07 to 0.64 wt. %) of precious metals (Pt and Pd) were added to the Ni-Mg/Ce0.6Zr0.4O2 reforming catalyst. Even low precious metal loadings substantially changed the reducibility of the support, the surface basic sites, and the activity for dry reforming of methane. Reduction temperature and surface basicity were identified as the two key parameters to achieve active low temperature reforming catalysts. The roles of oxidant composition beyond dry reforming and of the catalyst components are also evaluated. The results of these efforts may enable a number of intensified processes involving light hydrocarbons including hydrogen production, fuel cells, and solar fuels.

Methane activation and conversion via reforming using nonconventional catalysts and conditions

255th National Meeting (2018)

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