Search results for "catalyst"

Possibility of using NiCO2O4 alloy as catalyst for fuel electrode of hydrazine fuel cell

2016

The work presents a possibility of the use of NiCo2O4 alloys as catalysts for electrooxidation of hydrazine. The research was done by the method of polarizing cuvers of electrooxidation of hydrazine in glass vessel in aqueous solution of KOH, on electrode with NiCo2O4 alloy as a catalyst. Conducted measurements show that there is a possibility of electrooxidation of hydrazine on NiCo2O4 electrode. The current density is low, but the price of the catalyst is much lower than platinum.

Possibility of using NiCo2O4 alloy as catalyst for fuel electrode of hydrazine fuel cell

2017

Szerokie stosowanie ogniw paliwowych ograniczone jest głównie wykorzystywaniem drogich katalizatorów. Wyeliminowanie platyny umożliwiłoby szeroką komercjalizację tych ogniw. Artykuł przedstawia analizę elektroutleniania hydrazyny na katalizatorze NiCo2O4. Jako elektrolit wykorzystano wodny roztwór KOH. Pomiarów dokonano potencjostatem. Wykazano możliwość elektroutleniania hydrazyny na katalizatorze NiCo2O4. W każdym przypadku (dla wszystkich stężeń hydrazyny i udziałów Co) proces elektroutleniania zachodził. Gęstość prądu wynosiła 15–35 mA/cm2 dla wszystkich koncentracji hydrazyny i elektrolitu. Gęstość prądu jest niewielka, jednak koszt uzyskania katalizatora jest znacznie niższy od kosztó…

Stop Ni - Co jako katalizator anody ogniwa paliwowego zasilanego alkoholem metylowym

2016

Kompleksy metali przejściowych z zasadami Lewisa jako prekursory katalizatorów polimeryzacji olefin. Cz. I. Postęp w komputerowym modelowaniu procesu…

2001

A review with 35 references covering molecular modeling in coordination polymerization over homogeneous and heterogeneous Ziegler-Natta catalysts. The study includes supports, cocatalysts, Lewis bases and solvents. Recent progress in elucidating the mechanisrn of elementary polymerization steps is presented against the background of rapidly deveIoping computational methods and available computational power. Theoretical studies on polymerization mcchanisms and structure of active centers are described (egns. 1-4). Authors own calculations are used to compare [MtC14(THF)2] complex-based (Mt = Ti, Hf or Zr) heterogeneous catalysts. The geometrical characteristics of precursors is presented (Ta…

Halloysite Nanotubes as Support for Metal-Based Catalysts

Halloysite nanotubes (HNTs) are a natural, biocompatible, environmental friendly and cheap double-layered aluminosilicate mineral that has a predominantly hollow tubular structure. The general stoichiometry of halloysite is Al2Si2O5·4(H2O). The layer units consist of a tetrahedral SiOH sheet stacked with an edge shared octahedral AlO6 sheet with an internal aluminol group AlOH. A water layer exists between the adjacent two layers. Thanks to their structural features, HNTs are suitable for a potential application as support for catalytic composites. Recently, we reported the synthesis of novel palladium-based catalytic systems using halloysite nanotubes modified with imidazolium or triazoliu…

GREEN CONDITIONS FOR THE SUZUKI REACTIONS BY USING MICROWAVE IRRADIATION AND MODIFIED HALLOYSITE/Pd CATALYST

2014

Halloysite nanotube (HNT) is an emerging biocompatible material with appealing perspective for technological applications, such as in catalysis1 and in pharmaceutical research.2 Halloysite is a double-layered aluminosilicate mineral that has a predominantly hollow tubular structure. The functionalization of HNTs is a good strategy to introduce an organic moiety onto the external surface and, therefore, to obtain innovative catalyst supports.3 We have modified the external surface of halloysite nanotube with octylimidazolium moieties (HNT-IL) by microwave irradiation in solvent-free conditions and we have have employed this material as support catalyst of Pd nanoparticles. The new HNT/Pd cat…

SYNTHESIS AND EVALUATION OF CATALYTIC ACTIVITY IN WATER AND MICROWAVE IRRADIATION OF A NEW SUPPORT BASED ON HNT TRIAZOLIUM SALTS

2014

In the last years SILLP (supported ionic liquid-like phase)-based materials prepared by covalent attachment have been synthesized [1]. Recently, we have synthesized a palladium-based catalytic system using halloysite nanotubes modified with octylimidazolium moieties and we have tested it in the Suzuki cross-coupling reaction under traditional heating, microwave irradiation and a very small amount of Pd catalyst [2,3]. It is known that support based on triazole motif showed superior activity to the analogous imidazole molecules [4] so, we have focused our attention to develop a new SILLP system with triazolium moiety. Herein we report the synthesis of an original Pd-dicationic triazolium sup…

Mechanistic Origins of the pH Dependency in Au-Catalyzed Glycerol Electro-oxidation: Insight from First-Principles Calculations

2021

Electrocatalytic oxidation of glycerol (EOG) is an attractive approach to convert surplus glycerol to value-added products. Experiments have shown that EOG activity and selectivity depend not only on the electrocatalyst but also on the electrode potential, the pH, and the electrolyte. For broadly employed gold (Au) electrocatalysts, experiments have demonstrated high EOG activity under alkaline conditions with glyceric acid as a primary product, whereas under acidic and neutral conditions Au is almost inactive producing only small amounts of dihydroxyacetone. In the present computational work, we have performed an extensive mechanistic study to understand the pH and potential dependency of …

Heterogeneous Photocatalysis for Selective Formation of High-Value-Added Molecules: Some Chemical and Engineering Aspects

2018

This review deals with the parameters that influence heterogeneous photocatalysis (PC) for selective synthesis of high-value chemicals by itself or in combination with other technologies. In particular, the parameters related to the photocatalysts, such as crystallinity degree, type of polymorph, surface acid-base properties, exposure of particular crystalline facets, coupling of different semiconductors, position of the valence and conduction band edge, addition of doping agents, and those related to the reaction system, such as setup configuration and reactor geometry, type of solvent, type and amount of photocatalyst, affecting the selectivity toward specific products are described and d…

Influence of a Cu–zirconia interface structure on CO2 adsorption and activation

2021

CO2 adsorption and activation on a catalyst are key elementary steps for CO2 conversion to various valuable products. In the present computational study, we screened different Cu–ZrO2 interface structures and analyzed the influence of the interface structure on CO2 binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favors one position on both tetragonal and monoclinic ZrO2 surfaces, where the bottom Cu atoms are placed close to the lattice oxygens. In agreement with previous calculations, we find that CO2 prefers a bent bidentate configuration at the Cu–ZrO2 interface and the molecule is clearly activated being negatively charged. Strain…