Strategy for stabilizing noble metal nanoparticles without sacrificing active sites

We report a facile surface fluorination strategy for restricting Pt nanoparticle sintering through providing anchoring sites on the TiO2 support and enhancing metal–support interaction via improved electronic interaction without sacrificing the active sites.

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Noble metal enhanced photocatalytic activity of heterostructured TiO2 spheres with tunable interiors and shells

Functional Materials Letters ◽

10.1142/s1793604720500393 ◽

2020 ◽

Vol 13 (08) ◽

pp. 2050039

Author(s):

Bo Qiu ◽

Xin Xiao ◽

Min Zhang ◽

Yue Mao ◽

Xiaoheng Liu

Keyword(s):

Metal Nanoparticles ◽

Noble Metal ◽

Precious Metal ◽

Active Sites ◽

Inner Core ◽

Catalytic Performance ◽

Noble Metal Nanoparticles ◽

Oxide Support ◽

Metal Support Interaction ◽

Metal Support

Heterostructured TiO2 spheres with tunable interiors and shells were prepared by self-template technology. This structure is composed of a hollow shell and an inner core which can enhance light scattering in the hollow space and provide a large surface to generate sufficient active sites. Besides, the nanosheets grown on the shell layer not only increased their specific surface area, but also exposed more surface-active sites. The performance of photocatalysts was estimated by the RhB decolorization, and experimental results show that the photoactivity can be greatly improved by depositing noble metal nanoparticles. It improves the efficiency of charge utilization and enhances the overall catalytic performance from the three stages of charge carrier generation, separation and surface reaction. The strong metal–support interaction (SMSI) between the noble metal nanoparticles and the oxide support has been proven to inhibit the supported precious metal, one strategy for nanoparticle aggregation and growth. On the one hand, the nanoshells isolate the precious metal nanoparticles from each other, preventing the aggregation of metal nanoparticles.

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Co-processing of hydrodeoxygenation and hydrodesulfurization of phenol and dibenzothiophene with NiMo/Al2O3–ZrO2 and NiMo/TiO2–ZrO2 catalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0148 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jesús Andrés Tavizón Pozos ◽

Gerardo Chávez Esquivel ◽

Ignacio Cervantes Arista ◽

José Antonio de los Reyes Heredia ◽

Víctor Alejandro Suárez Toriello

Keyword(s):

Active Sites ◽

Reaction Rate ◽

Supported Catalysts ◽

Initial Reaction Rate ◽

Initial Reaction ◽

Competition Effect ◽

Support Interaction ◽

Highly Active ◽

Metal Support Interaction ◽

Metal Support

Abstract The influence of Al2O3–ZrO2 and TiO2–ZrO2 supports on NiMo-supported catalysts at a different sulfur concentration in a model hydrodeoxygenation (HDO)-hydrodesulfurization (HDS) co-processing reaction has been studied in this work. A competition effect between phenol and dibenzothiophene (DBT) for active sites was evidenced. The competence for the active sites between phenol and DBT was measured by comparison of the initial reaction rate and selectivity at two sulfur concentrations (200 and 500 ppm S). NiMo/TiO2–ZrO2 was almost four-fold more active in phenol HDO co-processed with DBT than NiMo/Al2O3–ZrO2 catalyst. Consequently, more labile active sites are present on NiMo/TiO2–ZrO2 than in NiMo/Al2O3–ZrO2 confirmed by the decrease in co-processing competition for the active sites between phenol and DBT. DBT molecules react at hydrogenolysis sites (edge and rim) preferentially so that phenol reacts at hydrogenation sites (edge and edge). However, the hydrogenated capacity would be lost when the sulfur content was increased. In general, both catalysts showed similar functionalities but different degrees of competition according to the highly active NiMoS phase availability. TiO2–ZrO2 as the support provided weaker metal-support interaction than Al2O3–ZrO2, generating a larger fraction of easily reducible octahedrally coordinated Mo- and Ni-oxide species, causing that NiMo/TiO2–ZrO2 generated precursors of MoS2 crystallites with a longer length and stacking but with a higher degree of Ni-promotion than NiMo/Al2O3–ZrO2 catalyst.

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