New approach to the preparation of highly dispersed transition metals sulfides and nitrides
•Addition of CCl4 strongly increases reactivity for gas-phase sulfidation and nitridation of oxides.•CCl4 acts as oxygen scavenger by an acid-base mechanism.•Mesoporous molybdenum and tungsten nitrides obtained at 500 °C.•Titanium sulfide obtained from oxide at 600 °C.•Semiconducting nitrides and oxynitrides obtained at low temperature.
Gas–solid reactions leading to bulk or supported nitride and sulfide catalysts conventionally involve interaction of oxide precursors with NH3 or H2S flow. Addition of gaseous oxygen acceptors, such as carbon tetrachloride, to the treatment gas flow changes the reaction pathway and opens new possibilities for the preparation of highly divided sulfides and nitrides. Thus, sulfidation or nitridation of the electropositive transition metals oxides becomes possible under relatively soft conditions. Otherwise, novel original 2D and hollow morphologies become available. Latest achievements using this approach are reviewed and original results are presented for the preparation of sulfides and nitrides. A critical analysis of the possibilities and limitations of the new approach is provided with emphasis on the preparation of highly divided catalytic materials.
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Journal: Catalysis Today - Volume 250, 15 July 2015, Pages 134–144