Analysis of sulfur-induced selectivity changes for anhydrous methanol dehydrogenation on Ni(100) surfaces

The absorption of sulfur on the Ni(100) surface has been reported to influence its product selectivity for methanol dehydrogenation. While dehydrogenation on the clean Ni(100) surface primarily produces a mixture of carbon monoxide and hydrogen, preadsorption of 0.25–0.33 monolayers of sulfur shifts the selectivity to mainly formaldehyde and hydrogen. Density functional theory calculations of clean and sulfur-modified Ni(100) surfaces demonstrate that sulfur destabilizes methanol dehydrogenation reaction intermediates in a manner consistent with this shift in selectivity. Microkinetic modeling of the reaction system further indicates that these changes alter the reaction selectivities from CO to CH2O production in the steady state. The reaction selectivities of metal alloy surfaces, which also have heterogeneous surface morphologies, are hypothesized to be influenced in a similar manner as these S/Ni(100) surfaces.