Aromatic hydrogenation is an important refining technology that typically uses supported noble metal or alloy catalysts.  Sulfur is present in most feeds that require hydrogenation and it can titrate nearly all of the active noble metal surface sites, leaving only a fraction accessible for reaction.  Nonetheless, for feeds with sulfur levels of ~250ppm or less, the noble metals still provide the most effective aromatic saturation activity, with the transition metal sulfides becoming more active at higher sulfur levels.  In the absence of sulfur, Pt is much more active than Pd for hydrogenation and there are many literature citations illustrating that Pt-Pd bimetallic catalysts are tolerant to a higher level of sulfur making these mixed metal catalysts more active than independent metals.  The fundamental basis for the sulfur tolerance imparted by the bimetallic was explored in a systematic study by synthesizing a series of catalysts with Pt-Pd ratios between 1:0 and 0:1 (with a constant mole loading of total metal) on a silica support prepared using previously reported techniques. Toluene hydrogenation was used as a model reaction and dipropyldisulfide and dibenzothiophene were used as the sources of sulfur.<br/>This study used carefully prepared materials to establish reactivity trends along with spectroscopy to identify the catalyst sites responsible for highest activity in toluene hydrogenation at different concentrations of sulfur.  It establishes that a bimetallic nanoparticle does not provide increased catalytic activity during toluene hydrogenation.<br/>

Investigation of sulfur tolerance in supported Pt-Pd catalysts for aromatic saturation

254th National Meeting (2017)

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