Impact of molecular structure on the hydrogenation and oligomerization of diolefins over a Ni-Mo-S/γ-Al2O3 catalyst

Inhibition of Diolefin Hydrogenation by Quinoline

“…42 Even at 96% conversion of 2,5-dimethyl-2,4hexadiene, its hydrogenation products at 180 °C over a spent commercial NiMo catalyst were the alkene (24% yield) and alkane (70% yield). 2 For the same 2,5-dimethyl-2,4-hexadiene hydrogenation but over Pd catalysts, Karakhanov et al 10 suggested that the formation of 2,5-dimethyl-2-hexene and trans-2,5-dimethyl-3-hexene occur via hydrogenation−isomerization reactions involving the rotation of a tri-substituted cation around the double bond. The relatively large Ni nanoparticles used in this work allow the flat-lying πadsorption mode during hydrogenation and isomerization, which is especially important for the branched dienes with internal double bonds.…”

“…3,6 Olefinic hydrocarbons with conjugated double bonds have a higher tendency to form dimers, which increases with diolefin concentration in the feed. 2 Olefins with internal double bonds are also more resistant to saturation than those with terminal double bonds. 5 The reactivity of olefins and diolefins depends strongly on their structure.…”

“…12 In industry, hydrotreating NiMo catalysts are typically used to hydrogenate the olefin-containing feed 3 and thus are addressed in academic literature. 2,4,5 Earlier studies compared the performance of Mo, CoMo, and NiMo catalysts for olefin hydrogenations. 22,23 At 150 °C, the NiMo catalyst was found to be 20 times more active than Mo, but the comparison with Ni-only catalyst was not performed.…”

“…4 The same group evaluated the impact of the diolefin structure on their hydrogenation and oligomerization and concluded that olefins with conjugated double bonds gave higher dimer yields, which were also affected by the steric hindrance. 2 When hydrodesulfurization (HDS) occurs concomitantly with olefin hydrogenation at increased temperatures (220−260 °C), the formed H 2 S reacts with olefins to form thiols that are further desulfurized and produced saturated hydrocarbons; conversions of C 6 olefins thus increased with the increment of sulfur content from 62 to 1983 ppm in the feed. 7 At the temperatures of desulfurization, sulfur addition to the feed is essential to preserve the activity and selectivity of metal sulfide catalysts.…”

Effect of Carbon Number and Molecular Structure of Olefin on HDO Activity and Hydrogenation Pathway

“…From here, the hydrogenation of olefins and the main influence factors have been well studied. However, the conclusions obtained in these studies were based on the olefins with small carbon number (such as C5 and C6 olefins) in FCC gasoline or model feed. − The olefins hydrogenated in the HDS unite of FCC gasoline were C7–C9 olefins in the refinery. , In addition, the hydrogenation of olefins has a great relationship with its carbon number . The conclusions obtained above were not well applied to the hydrogenation of C7–C9 olefins in FCC gasoline. ,,− It is necessary to investigate the effect of carbon number and molecular structure of olefin on its hydrogenation activity.…”