The novel approach based on 33 S isotope tracing is proposed for the elucidation of hydrodesulfurization (HDS) mechanisms and characterization of molybdenum sulfide catalysts. The technique involves sulfidation of the catalyst with 33 S-isotope-labeled dihydrogen sulfide, followed by monitoring the fate of the 33 S isotope in the course of the hydrodesulfurization reaction by online mass spectrometry and characterization of the catalyst after the reaction by temperature-programmed oxidation with mass spectrometry (TPO-MS). The results point to different pathways of thiophene transformation over Co or Ni-promoted and unpromoted molybdenum sulfide catalysts, provide information on the role of promoter and give a key for the design of new efficient HDS catalysts.
Keywords: heterogeneous catalysis; hydrodesulfurization; isotope tracing; mass spectrometry; sulfur.
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