Catalytic Oxidation of Toluene with Ozone Over the Ru-Mn/Desilicated Nanoporous H-Zeolite Socony Mobil-5 at Room Temperature

In this study, the effect of Ru-Mn bimetallic catalysts in combination with a zeolite support on the removal of toluene in the presence of ozone at room temperature was investigated. Desili-cated HZSM-5 (DZSM) was fabricated and applied as a Ru-Mn support for the removal of toluene (100 ppm) in the presence of ozone (1000 ppm) at room temperature. The surface area, pore volume, and average pore size of Ru-Mn with a DZSM support (RuMn/DZSM) were measured and compared with those of Ru-Mn/HZSM-5 (RuMn/HZSM). The pore size of RuMn/DZSM (69 Å) was much larger than that of RuMn/HZSM-5 (5.5 Å). In addition, the pore volumes of RuMn/DZSM and RuMn/HZSM were 0.64 and 0.25 cm3/g, respectively. Furthermore, the ratios of Mn3+/Mn4+ and Ovacancy/Olattice of RuMn/DZSM were larger than those of RuMn/HZSM-5. The removal efficiency of toluene of RuMn/DZSM was higher than that of RuMn/HZSM due to its larger pore volume, pore size, and the increased ratios of Mn3+/Mn4+ and Ovacancy/Olattice.

One-Pot Synthesis of Ultra-Small Pt Dispersed on Hierarchical Zeolite Nanosheet Surfaces for Mild Hydrodeoxygenation of 4-Propylphenol

The rational design of ultra-small metal clusters dispersed on a solid is of crucial importance in modern nanotechnology and catalysis. In this contribution, the concept of catalyst fabrication with a very ultra-small size of platinum nanoparticles supported on a hierarchical zeolite surface via a one-pot hydrothermal system was demonstrated. Combining the zeolite gel with ethylenediaminetetraacetic acid (EDTA) as a ligand precursor during the crystallization process, it allows significant improvement of the metal dispersion on a zeolite support. To illustrate the beneficial effect of ultra-small metal nanoparticles on a hierarchical zeolite surface as a bifunctional catalyst, a very high catalytic performance of almost 100% of cycloalkane product yield can be achieved in the consecutive mild hydrodeoxygenation of 4-propylphenol, which is a lignin-derived model molecule. This instance opens up perspectives to improve the efficiency of a catalyst for the sustainable conversion of biomass-derived compounds to fuels.

Effect of a modified 13X zeolite support in Pd-based catalysts for hydrogen oxidation at room temperature

This study investigated the effect of a modified 13X zeolite to Pd/zeolite catalyst on the oxidation of hydrogen to ensure safety from hydrogen leakage.

Lights and Shadows of Gold Introduction into Beta Zeolite

Four different methods for gold deposition on Beta zeolite, namely impregnation, ion-exchange, deposition-reduction, and grafting on (3-aminopropyl)trimethoxysilane functionalized support, were applied to investigate their influence on textural/structural changes in the zeolite support and its surface acidity. The as-prepared materials were fully characterized by XRD, N2 physisorption, ICP-OES, XPS, TEM, and pyridine adsorption. The obtained results indicated that bifunctional redox–acidic materials prepared within this work were characterized not only by different gold loading and gold particle size, but also different textural parameters and acidity. All these features were strongly affected by the procedure applied for gold deposition. The introduction of Au into Beta zeolite by ion exchange caused a significant decrease in the Si/Al ratio in the zeolite framework. The size of Au particles determined the textural parameters of the zeolite and the number of Lewis acid sites (LAS). The Brønsted acid sites (BAS) number was decreased if (3-aminopropyl)trimethoxysilane or NaBH4 were used in the procedure of gold deposition. The highest BAS/LAS ratio was achieved for the sample prepared by ion exchange in the ammonium form of Beta zeolite. The presented results permit making a proper choice of the gold modification procedure for the preparation of bifunctional (redox–acidic) materials, addressed to a desired application.

Outstanding Performance of Highly-Dispersed Zinc Species on Zeolites for the Continuous and Selective Dehydrogenation of Ethane with CO2 as Soft Oxidant

<div> <div> <div> <p>We report herein the preparation, characterization, and outstanding catalytic performance of a series of heterogeneous catalysts featuring highly-dispersed zinc sites on zeolitic SSZ-13 and ZSM-5 frameworks. The materials were evaluated in the oxidative dehydrogenation of ethane with CO2 as a soft oxidant, a very important reaction for the synthesis of platform chemicals. In particular, we found that Zn2.92/NaS50 exhibits high ethane conversion ability, excellent CO2 transformation ability, and good selectivity. In line with the experimental results, we show that the highly-selective character is due to the characteristic compositional structure of the zeolite support and its topology that can effectively confine CO2. An in-depth molecular analysis via operando studies and DFT calculation showed that the rate-limiting step of reaction with CO2 was the second C-H bond dissociation to give ethene. The addition of CO2 effectively reduced the energy barrier of this step, favoring desorption and limiting byproduct formation. Overall, this work demonstrates the breakthrough potential of novel heterogeneous catalysts made of highly-dispersed zinc species on zeolites in relevant transformations. </p> </div> </div> </div>

Outstanding Performance of Highly-Dispersed Zinc Species on Zeolites for the Continuous and Selective Dehydrogenation of Ethane with CO2 as Soft Oxidant

<div> <div> <div> <p>We report herein the preparation, characterization, and outstanding catalytic performance of a series of heterogeneous catalysts featuring highly-dispersed zinc sites on zeolitic SSZ-13 and ZSM-5 frameworks. The materials were evaluated in the oxidative dehydrogenation of ethane with CO2 as a soft oxidant, a very important reaction for the synthesis of platform chemicals. In particular, we found that Zn2.92/NaS50 exhibits high ethane conversion ability, excellent CO2 transformation ability, and good selectivity. In line with the experimental results, we show that the highly-selective character is due to the characteristic compositional structure of the zeolite support and its topology that can effectively confine CO2. An in-depth molecular analysis via operando studies and DFT calculation showed that the rate-limiting step of reaction with CO2 was the second C-H bond dissociation to give ethene. The addition of CO2 effectively reduced the energy barrier of this step, favoring desorption and limiting byproduct formation. Overall, this work demonstrates the breakthrough potential of novel heterogeneous catalysts made of highly-dispersed zinc species on zeolites in relevant transformations. </p> </div> </div> </div>