Supported Metal Catalysts: Preparation, Characterization, and Function

Palladium Nanoparticle Size Effect in Hydrodesulfurization of 4,6‐Dimethyldibenzothiophene (4,6‐DMDBT)

“…As upport effect on sulfur poisoning of Pt catalysts was suggested to be negligible, apart from providing different metal nanoparticle sizes. [12] However,c omparing Figure 3b and Figure 6, the activity per surfacep alladium during 4,6-DMDBT conversion changed more dramatically on going from Pd "S" to Pd "M" catalysts compared with the sulfur-free hydrogenation. On addition of sulfur (as CS 2 )t ot he 3,3'-DMBP feed, all three catalysts exhibited two orders of magnitude lower hydrogenation rates, but the smallest Pd "S" nanoparticles were poisoned to the largeste xtent and showedt he lowest hydrogenation activity.T he drop in DDS and HYD activity was also reported for thiophene hydrogenation on Pt and Ru for smaller particle sizes and was ascribed to the stronger metal-sulfur bonds and lower activev acancy concentration on corner and edge sites that are prevalent on the smaller clusters.…”

“…As seen from Figure , in the sulfur‐free feed, the hydrogenation TOF increased with the particle size increase, which is in line with our above discussion on the larger particle requirement for the flat reactant adsorption. A support effect on sulfur poisoning of Pt catalysts was suggested to be negligible, apart from providing different metal nanoparticle sizes …”

“…[11] Av igorous investigationo fp latinum catalysts supported on av ariety of supports (alumina, silica, and molybdena) revealed that the observed support effect on the Pt sulfur poisoningc ould be ascribed to surface topography and linked to particle size rather than to ad irect support effect. [12] Ar ecent study on the sizedependents ulfur poisoning of Pt hydrogenation catalysts showedt hat the sulfur-free structure-insensitive hydrogenation becomess ize-dependent upon thiophenea ddition to the feed;i nt he presence of S, the turnover frequency increased approximately four-fold upon 2t o7 nm particles ize increase. [13] The current study aims to investigate the size effect of palladium nanoparticles on hydrodesulfurization of 4,6-DMDBTand understand the contribution of hydrogenation sites through 3,3'-dimethylbiphenyl (3,3'-DMBP) hydrogenation with and withouts ulfur addition.…”

“…Overall, sulfur poisoning is known to affect product distribution, such as by enhancing dehydrogenation over hydrogenolysis or boosting selectivity to methanol in syngas conversion . A vigorous investigation of platinum catalysts supported on a variety of supports (alumina, silica, and molybdena) revealed that the observed support effect on the Pt sulfur poisoning could be ascribed to surface topography and linked to particle size rather than to a direct support effect . A recent study on the size‐dependent sulfur poisoning of Pt hydrogenation catalysts showed that the sulfur‐free structure‐insensitive hydrogenation becomes size‐dependent upon thiophene addition to the feed; in the presence of S, the turnover frequency increased approximately four‐fold upon 2 to 7 nm particle size increase …”

The co-adsorption of carbon monoxide/propyne at 293 K and 573 K over a nickel/alumina catalyst

“…However as was shown in a study of hydrogen sulfide adsorption, [6] adsorption at room temperature followed by thermal desorption to a given temperature is not the same as adsorption at that temperature. However it soon becomes apparent that the main emphasis of the studies is adsorption at or below room temperature.…”