Bimetallic Pt–Pd/silica–alumina hydrotreating catalysts – Part I: Physicochemical characterization

Effect of catalyst precursor and its pretreatment on the amount of β-Pd hydride phase and HDS activity of Pd-Pt/silica-alumina

“…As to the other PdA-PtO and PdA-PtC catalysts, their higher PdH x contents point out to much smaller alloy amounts than in PdC-PtC. This result is in a good accordance with the earlier observations that showed that Pd and Pt compounds other than chlorides usually gave no alloy [3] or the less alloy accompanied by monometallic Pd particles [5,31].…”

“…On the other hand, both alloy and monometallic Pd particles were formed when Pd and Pt tetraamine carbonates and tetraamine nitrates were employed. The formation of monometallic Pd particles on Y zeolite obviously occurs at the higher Pd:Pt ratio [31], and the fraction of the monometallic Pd aggregates on a silica-alumina approaches 41% [5]. These data suggest that the presence of Pd-Pt alloy can almost certainly be expected when metal chlorides are used as precursors, while the isolated Pd and Pt particles or Pd particles coexisting with the alloy can be formed when different or chlorine-free metal compounds are used.…”

“…This is an interesting quantitative result concerning Pd-Pt/MSA catalyst. Quite recently, Yu with coworkers [6] proposed that sulfur tolerance of Pd-Pt catalysts should increase at higher reaction temperatures. One of the reasons in an easier removal of sulfur deposited on the metallic phase by hydrogen reduction.…”

“…Bimetallic catalysts containing Pd and Pt have primarily been studied for the purposes of hydrodearomatization of industrial feeds and hydrogenation (HYD) of aromatic model compounds in the presence of sulfur [1][2][3][4][5][6]. Parallel to this research, some studies have also been devoted to their evaluation in hydrodesulfurization (HDS) reactions of simple model compounds such as thiophene or dibenzothiophene [7,8] and for the deep HDS of substituted dibenzothiophenes [4,8,9].…”

Supported nanometric platinum–nickel catalysts for solvent-free hydrogenation of tetralin

“…A large concentration of aromatics in diesel oil decreases its quality such as cetane value, and increases the particle emissions from diesel engines [3,4]. Furthermore, the existing environmental legislations have brought more stringent requirements in terms of the aromatic content in diesel fuels [5][6][7]. This triggers extensive researches on highly active catalytic systems for hydrotreating processes in refinery industry.…”