Mercaptosilane-assisted synthesis of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials and their enhanced hydrogenation properties

Hydrogen Diffusion Guided Design of Pt-Based Alloys for Inhibition of Butadiene Over-Hydrogenation

Alloying Pt with other metals is an effective strategy to tune its performance towards selective hydrogenation reactions. Herein, we have demonstrated a process to screen Pt-based alloys for inhibition of butadiene over-hydrogenation with a model comprising isolated single atoms (ISA) embedded into Pt(111). DFT calculations reveal that the diffusion energy barrier of H co-adsorbed with 1-butene is a key parameter for the screening. The output from the ISA model was validated by testing several typical Pt-based alloys towards butadiene hydrogenation. Furthermore, an unexpected higher selectivity to cis-2-butene compared to the trans isomer and 1-butene over the PtZn alloy was explored employing the ISA model.

Engineering of Transition Metal Catalysts Confined in Zeolites

Transition metal-zeolite composites are versatile catalytic materials for a wide range of industrial and lab-scale processes. Significant advances in fabrication and characterization of well-defined metal centers confined in zeolite matrixes have greatly expanded the library of available materials and, accordingly, their catalytic utility. In this review, we summarize recent developments in the field from the perspective of materials chemistry, focusing on synthesis, postsynthesis modification, (operando) spectroscopy characterization, and computational modeling of transition metal-zeolite catalysts.

Internal defects-oriented dissolution: controllable evolution of hollow ZSM-5 nano-structures

A hollow ZSM-5 nanostructure with a shell thickness of ca. 40 nm is successfully formed in 40 min via ammonia leaching under mild conditions.

Synthesis of micro-mesoporous materials ZSM-5/FDU-12 and the performance of dibenzothiophene hydrodesulfurization

The micro-mesoporous materials ZF-x (ZSM-5-FDU-12, x = SiO₂/Al₂O₃) with different molar ratios of SiO₂/Al₂O₃ were synthesized by an in situ nano-assembly method with the ZSM-5 precursor serving as the silica source.

An iron-based micropore-enriched silica catalyst: in situ confining of Fe2O3 in the mesopores and its improved catalytic properties

With a novel anionic micelle templating method, Fe₂O₃ species were in situ formed and highly-dispersed and the pore size tailored to the microporous level (<2 nm). The catalyst exhibited high selectivity for dihydroxybenzene in phenol hydroxylation.

Synthesis of sub-nanosized Pt particles on mesoporous SBA-15 material and its application to the CO oxidation reaction

In this work, we show that the size and shape of Pt nanoparticles in SBA-15 can be controlled through vacuum and air calcination. The vacuum-calcination/H2-reduction process is used to thermally treat a 0.2 wt% Pt(4+)/SBA-15 sample to obtain small 2D clusters and single atoms that can significantly increase Pt dispersion in SBA-15. Compared with thermal treatments involving air-calcination/H2-reduction, which result in ∼4.6 nm rod-like Pt particles, vacuum-calcination/H2-reduction can dramatically reduce the size of the Pt species to approximately 0.5-0.8 nm. The Pt particles undergoing air-calcination/H2-reduction have poor conversion efficiency because the fraction of terrace sites, the major sites for CO oxidation, on the rod-like Pt particles is small. In contrast, a large amount of low-coordinated Pt sites associated with 2D Pt species and single Pt atoms in SBA-15 is effectively generated through the vacuum-calcination/H2-reduction process, which may facilitate CO adsorption and induce strong reactivity toward CO oxidation. We investigated the effect of vacuum-calcination/H2-reduction on the formation of tiny 2D clusters and single atoms by characterizing the particles, elucidating the mechanism of formation, determining the active sites for CO oxidation and measuring the heat of CO adsorption.