Ketonic/quinonic C=O groups on the surface of a carbon matrix are capable of abstracting hydrogen in C=H bonds from hydrocarbons and enable them to selectively convert into corresponding unsaturated hydrocarbons; this process is the oxidative dehydrogenation (ODH) reaction. However, a variety of inevitable defects or graphene edges and other oxygen-containing groups on the carbon matrix are detrimental to the selective production of alkenes due to their high activity towards overoxidation. Herein, we show that phosphate can not only impede the total oxidation but also cover the selective C=O groups, hence allowing its use as a modulator to defects and oxygen-containing functional groups on the multiwalled carbon nanotubes, regulating the distribution of active sites and related catalytic targets.

A novel, rapidly quenched skeletal Fe catalyst (RQ Fe) has been prepared by alkali leaching of the Fe 50 Al 50 alloy solidified by the rapid quenching technique and tested in gas phase Fischer-Tropsch synthesis (FTS). Characterizations demonstrate that the RQ Fe catalyst has larger specific surface area, smaller crystallite size, and higher population of the Fe(111) surface than the conventional Raney Fe catalyst prepared from the naturally solidified Fe 50 Al 50 alloy. As compared to Raney Fe, which has FTS activity equivalent to the precipitated Fe catalyst while higher than the fused Fe catalyst, RQ Fe is 25% more active. Promotion of the RQ Fe catalyst with Mn or K further improves the FTS activity, selectivities to alkenes and higher alkanes, as well as the catalytic stability, showing that the rapid quenching technique is promising in the preparation of skeletal Fe-based catalysts with improved FTS performance.

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