scholarly journals Titanosilicate zeolite precursors for highly efficient oxidation reactions

2020 ◽  
Vol 11 (45) ◽  
pp. 12341-12349
Author(s):  
Risheng Bai ◽  
M. Teresa Navarro ◽  
Yue Song ◽  
Tianjun Zhang ◽  
Yongcun Zou ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Oxidation Reactions ◽  
Highly Efficient ◽  
Oxidative Reactions ◽  
Open Structures ◽  
Catalytically Active ◽  
Zeolite Precursors

Titanosilicate zeolite precursors, with open structures of zeolite units and high amounts of catalytically active Ti species, show superior catalytic performance in the oxidative reactions.

Synthesis and oxidation catalysis of a Ti-substituted phosphotungstate, and identification of the active oxygen species

2015 ◽  
Vol 5 (10) ◽  
pp. 4778-4789 ◽  
Author(s):  
Eri Takahashi ◽  
Keigo Kamata ◽  
Yuji Kikukawa ◽  
Sota Sato ◽  
Kosuke Suzuki ◽  
...  
Keyword(s):  
Active Oxygen Species ◽  
Catalytic Performance ◽  
Active Species ◽  
Active Oxygen ◽  
Oxidation Catalysis ◽  
Oxygen Species ◽  
Oxidation Reactions ◽  
Catalytically Active

A Ti-substituted phosphotungstate (I) showed high catalytic performance for several oxidation reactions. The truly catalytically active species was successfully isolated, and its anion structure was determined.

scholarly journals Stable Non-Covalent Co(Salphen)-Based Polymeric Catalyst for Highly Efficient and Selective Oxidation of 2,3,6-Trimethylphenol

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1076
Author(s):  
Weijie Zhang ◽  
Lingling Hu ◽  
He Zhang ◽  
Chunyue Pan ◽  
Juntao Tang
Keyword(s):  
Cost Effective ◽  
Catalytic Performance ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
Efficient Catalyst ◽  
Highly Efficient ◽  
Catalyst Systems ◽  
Polymeric Catalyst ◽  
Substantial Decline ◽  
Excellent Stability

Developing highly efficient catalyst systems for phenol–quinone transformation is of great significance in the chemical/biological industries. Herein, we reported a novel heterogenous catalytic system based on Co(Salphen) supramolecular polymers (CSP), which delivered an excellent catalytic performance in the oxidation of 2,3,6-trimethylphenol (TMP) under mild conditions. The CSP were constructed through a simple self-assembled process between BiCo(Salphen) complex and 4,4-dipyridine. By applying BiCo-BiPy1:1 CSP as the catalyst, 2,3,5-trimethyl-1,4-benzoquinone (TMBQ) could be obtained with an excellent conversion (>99%) and selectivity over 99% under mild reaction conditions (30 °C, 0.1 MPa). In addition, it can be recycled at least five times without substantial decline in catalytic activities (conversion and selectivity), suggesting its excellent stability and recyclability. This work may provide guidance on designing and building valuable catalysts for environmentally friendly and cost-effective oxidation reactions.

scholarly journals Nickel Phosphide Catalysts as Efficient Systems for CO2 Upgrading via Dry Reforming of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 446
Author(s):  
Miriam González-Castaño ◽  
Estelle le Saché ◽  
Cameron Berry ◽  
Laura Pastor-Pérez ◽  
Harvey Arellano-García ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Lower Surface ◽  
Catalytic Performance ◽  
Dry Reforming Of Methane ◽  
Oxidation Reactions ◽  
Surface Areas ◽  
Ceo2 Sample ◽  
Conversion Rates ◽  
Ni Oxidation ◽  
Catalytic Behaviour

This work establishes the primordial role played by the support’s nature when aimed at the constitution of Ni2P active phases for supported catalysts. Thus, carbon dioxide reforming of methane was studied over three novel Ni2P catalysts supported on Al2O3, CeO2 and SiO2-Al2O3 oxides. The catalytic performance, shown by the catalysts’ series, decreased according to the sequence: Ni2P/Al2O3 > Ni2P/CeO2 > Ni2P/SiO2-Al2O3. The depleted CO2 conversion rates discerned for the Ni2P/SiO2-Al2O3 sample were associated to the high sintering rates, large amounts of coke deposits and lower fractions of Ni2P constituted in the catalyst surface. The strong deactivation issues found for the Ni2P/CeO2 catalyst, which also exhibited small amounts of Ni2P species, were majorly associated to Ni oxidation issues. Along with lower surface areas, oxidation reactions might also affect the catalytic behaviour exhibited by the Ni2P/CeO2 sample. With the highest conversion rate and optimal stabilities, the excellent performance depicted by the Ni2P/Al2O3 catalyst was mostly related to the noticeable larger fractions of Ni2P species established.

scholarly journals First of Its Kind Automotive Catalyst Prepared by Recycled PGMs-Catalytic Performance

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 942
Author(s):  
Anastasia Maria Moschovi ◽  
Mattia Giuliano ◽  
Marios Kourtelesis ◽  
Giovanna Nicol ◽  
Ekaterini Polyzou ◽  
...  
Keyword(s):  
Oxygen Storage Capacity ◽  
Catalytic Performance ◽  
Platinum Group Metals ◽  
Oxygen Storage ◽  
Small Scale ◽  
Gas Mixture ◽  
Oxidation Reactions ◽  
Fresh Catalyst ◽  
Metal Precursors ◽  
Automotive Catalytic Converters

The production of new automotive catalytic converters requires the increase of the quantity of Platinum Group Metals in order to deal with the strict emission standards that are imposed for vehicles. The use of PGMs coming from the recycling of spent autocatalysts could greatly reduce the cost of catalyst production for the automotive industry. This paper presents the synthesis of novel automotive Three-Way Catalysts (PLTWC, Pd/Rh = 55/5, 60 gPGMs/ft3) and diesel oxidation catalysts (PLDOC, Pt/Pd = 3/1, 110 gPGMs/ft3) from recovered PGMs, without further refinement steps. The catalysts were characterized and evaluated in terms of activity in comparison with benchmark catalysts produced using commercial metal precursors. The small-scale catalytic monoliths were successfully synthesized as evidenced by the characterization of the samples with XRF analysis, optical microscopy, and N2 physisorption. Hydrothermal ageing of the catalysts was performed and led to a significant decrease of the specific surface area of all catalysts (recycled and benchmarks) due to sintering of the support material and metal particles. The TWCs were studied for their activity in CO and unburned hydrocarbon oxidation reactions under a slightly lean environment of the gas mixture (λ > 1) as well as for their ability to reduce NOx under a slightly rich gas mixture (λ < 1). Recycled TWC fresh catalyst presented the best performance amongst the catalysts studied for the abatement of all pollutant gases, and they also showed the highest Oxygen Storage Capacity value. Moreover, comparing the aged samples, the catalyst produced from recycled PGMs presented higher activity than the one synthesized with the use of commercial PGM metal precursors. The results obtained for the DOC catalysts showed that the aged PLDOC catalyst outperformed both the fresh catalyst and the aged DOC catalyst prepared with the use of commercial metal precursors for the oxidation of CO, hydrocarbons, and NO. The latter reveals the effect of the presence of several impurities in the recovered PGMs solutions.

scholarly journals Exploiting the Potential of Biosilica from Rice Husk as Porous Support for Catalytically Active Iron Oxide Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1259
Author(s):  
Ana Franco ◽  
Rafael Luque ◽  
Carolina Carrillo-Carrión
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Rice Husk ◽  
Heterogeneous Catalysts ◽  
Catalytic Performance ◽  
Added Value ◽  
Oxide Nanoparticles ◽  
Porous Support ◽  
Green Materials ◽  
Catalytically Active

Biomass-derived materials are put forward as eco-friendly alternatives to design heterogeneous catalysts. To contribute in this field, we explored the potential of mesoporous biogenic silica (RH-Silica) obtained from lignocellulosic waste, in particular from rice husk, as an inorganic support to prepare heterogenized iron oxide-based catalysts. Mechanochemistry, considered as a green and sustainable technique, was employed to synthetize iron oxide nanoparticles in pure hematite phase onto the biosilica (α-Fe2O3/RH-Silica), making this material a good candidate to perform catalyzed organic reactions. The obtained material was characterized by different techniques, and its catalytic activity was tested in the selective oxidation of styrene under microwave irradiation. α-Fe2O3/RH-Silica displayed a good catalytic performance, achieving a conversion of 45% under optimized conditions, and more importantly, with a total selectivity to benzaldehyde. Furthermore, a good reusability was achieved without decreasing its activity after multiple catalytic cycles. This work represents a good example of using sustainable approaches and green materials as alternatives to conventional methods in the production of high-added value products.

Catalytic activity of Co-åkermanite and Co-pyroxene in oxidation reactions

2011 ◽  
Vol 89 (8) ◽  
pp. 939-947 ◽  
Author(s):  
Irena Mihailova ◽  
Dimitar Mehandjiev
Keyword(s):  
Catalytic Activity ◽  
Solid Phase ◽  
Sol Gel ◽  
Cobalt Content ◽  
Octahedral Coordination ◽  
Tetrahedral Coordination ◽  
Oxidation Reactions ◽  
Oxidation Of Co ◽  
Phase Synthesis ◽  
Catalytically Active

Two calcium–cobalt silicates were synthesized in which cobalt occupies different structural positions. The crystal phases belong to two main structural silicate types. In the Co-åkermanite structure (Ca2CoSi2O7), cobalt cations take tetrahedral coordination toward oxygen atoms. In the Co-pyroxene structure of CaCoSi2O6, cobalt displays octahedral coordination. Ca2CoSi2O7 was prepared by solid-phase synthesis and CaCoSi2O6 was prepared by sol–gel method. The synthesis of the phases was confirmed by XRD, FTIR, and EPR data. On the basis of the XPS analysis, it can be concluded that Co2+ cations exist in the studied silicates. Thus, it is possible to study the catalytic activity of two silicate phases containing Co2+ cations in different coordinations: tetrahedral and octahedral. It was found that cobalt silicates with crystal structures corresponding to pyroxene and åkermanite possess catalytic activity in the reactions of complete oxidation of CO and toluene. Co-pyroxene exhibits higher catalytic activity than Co-åkermanite, but the higher cobalt content on the surface of Co-pyroxene should also be taken into account. Then, it turns out that catalytically active complexes with Со2+ ions in tetrahedral coordination are more efficient than those with such ions in octahedral coordination when equal concentrations of cobalt were used on the surface of the catalysts.

Efficient Modulation of Catalytic Performance of Electrocatalytic Nitrogen Reduction with Transition Metal Anchored N/O-codoped Graphene by Coordination Engineering

2021 ◽  
Author(s):  
Xiaolin Wang ◽  
Li-Ming Yang
Keyword(s):  
Nitrogen Fixation ◽  
Transition Metal ◽  
High Throughput ◽  
First Principles ◽  
High Throughput Screening ◽  
Catalytic Performance ◽  
Nitrogen Reduction ◽  
Highly Efficient ◽  
First Time

We for the first time report the discovery of a series of highly efficient electrocatalysts, i.e., transition metal anchored N/O-codoped graphene, for nitrogen fixation via high-throughput screening combined with first-principles...

scholarly journals Catalytic synergy effect of MoS2/reduced graphene oxide hybrids for a highly efficient hydrogen evolution reaction

RSC Advances ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. 5480-5487 ◽  
Author(s):  
Jung Eun Lee ◽  
Jaemin Jung ◽  
Taeg Yeoung Ko ◽  
Sujin Kim ◽  
Seong-Il Kim ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electronic Transition ◽  
Catalytic Performance ◽  
Synergy Effect ◽  
Tafel Slope ◽  
Reduced Graphene ◽  
Catalytically Active

GO content tuning gradually enhanced the HER catalytic performance of the MoS2/rGO hybrids, decreasing the Tafel slope from 82 to 48 mV per decade owing to an increase of catalytically active areas and an electronic transition of MoS2.

One-Step Synthesis of Rod-Shaped NiFe-MOF as a Highly Efficient Oxygen Evolution Catalyst

NANO ◽  
2019 ◽  
Vol 14 (08) ◽  
pp. 1950101 ◽  
Author(s):  
Dandan Zhang ◽  
Renxing Huang ◽  
Huaming Xie ◽  
Xingyong Liu ◽  
Ying Lei ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Low Cost ◽  
Metal Organic Framework ◽  
Electrochemical Techniques ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Highly Efficient ◽  
Transmission Electron

Development of low-cost, highly active catalyst for efficient oxygen evolution reaction based on earth-abundant metals is still a great challenge. Here, we report that a rod-like bimetallic NiFe metal-organic framework (NiFe-MOF) can directly act as a highly efficient oxygen evolution reaction (OER) catalyst synthesized by a convenient-to-operate hydrothermal method. The rod-like NiFe-MOF can derive 10[Formula: see text]mA[Formula: see text]cm[Formula: see text] with a low overpotential of only 26[Formula: see text]mV, and its Tafel slope is 40.82[Formula: see text]mV[Formula: see text]dec[Formula: see text], which is superior to that of monometallic Ni-MOF or Fe-MOF, and even can be comparable to that of RuO2. To identify the origin of enhancing OER activity, we resorted to X-ray diffraction, scanning electron microscope, transmission electron microscope, high resolution transmission electron microscopy image and nitrogen adsorption–desorption techniques and various electrochemical techniques to probe it gingerly. The results indicate that its high electrochemically active area and the synergistic effect of bimetallic node could be responsible for the surprisingly high catalytic performance of the NiFe-MOF. These results suggest that this kind of bimetallic MOF (NiFe-MOF) could be a promising electrocatalyst for oxygen evolution reaction.

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