EXAFS study on the sulfidation behavior of Pd, Pt and Pd–Pt catalysts supported on amorphous silica and high-silica USY zeolite

X-Ray Photoelectron Spectroscopy Investigation of Pd-Beta Zeolite Catalysts with Different Acidities

“…On the contrary to the fresh samples, comparability of the Pd 3d /Si 2p ratio with the fraction of the AlPd x O crystallites in the samples is very good (Fig. 9) referring to expected formation of larger AlPd x O species (Table 3) and their larger variance after reduction [50].…”

Hydrodesulfurization of 4,6-dimethyldibenzothiophene over Pt, Pd, and Pt–Pd catalysts supported on amorphous silica–alumina

“…All Pd-containing catalysts converted 4,6-DM-DBT almost exclusively through the HYD route (99%). The Pt-Pd/ ASA catalyst behaved very similarly to Pd/ASA, which indicates that its surface properties are very close to those of Pd/ ASA [27], most probably due to Pd segregation on the catalyst surface [28]. The initial TOF DDS and TOF HYD for the DDS and HYD reaction pathways, respectively, calculated from the initial selectivities of these two pathways and the turnover frequencies TOF, show that Pt/ASA is 55 times faster and PtPd/ASA 10 times faster than Pd/ASA in the DDS pathway.…”

“…Therefore, the metal-support interaction remains strong, the agglomeration of the noble metal particles is prevented, and the dispersion and catalytic activity remain high. Very small Pt particles have a higher sulfur resistance because of their better contact with the acidic support, leading to a more pronounced electrondeficient character [13,27,45]. An increase in the particle size decreases the sulfur tolerance of Pt and Pd supported on highsilica zeolite [58].…”

Effect of the coexistence of nitrogen compounds on the sulfur tolerance and catalytic activity of Pd and Pt monometallic catalysts supported on high-silica USY zeolite and amorphous silica

“…In our previous measurements, highly dispersed Pd-Pt bimetallic particles supported on a high-silica USY zeolite and silica with small mesopores (pore diameter = 30 Å ) showed high sulfur tolerance on the part of the Pd-Pt bimetallic particles and high aromatic hydrogenation activity, although these supports were less acidic [6]. This suggests that electronic interaction between the noble metal particles and www.elsevier.com/locate/apcata Applied Catalysis A: General 293 (2005) 137-144 supports via multiple contacts of the metal particles with the mesopore walls might result in better sulfur tolerance on the part of noble metals [7]. In addition to the sulfur tolerance of noble metal catalysts, their tolerance to nitrogen is an important issue because most petroleum feedstocks contain nitrogenous compounds.…”