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Related Concept Videos

Catalysis02:50

Catalysis

The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
Catalysis01:27

Catalysis

Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
Heterogeneous Catalysis01:22

Heterogeneous Catalysis

Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
Free Energy Changes for Nonstandard States03:25

Free Energy Changes for Nonstandard States

The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:
Preparation of Amines: Alkylation of Ammonia and Amines01:30

Preparation of Amines: Alkylation of Ammonia and Amines

Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Reduction of Alkenes: Catalytic Hydrogenation02:13

Reduction of Alkenes: Catalytic Hydrogenation

Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...

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Related Experiment Video

Updated: Jun 5, 2026

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
08:40

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

Published on: December 6, 2021

High-temperature stable, iron-based core-shell catalysts for ammonia decomposition.

Mathias Feyen1, Claudia Weidenthaler, Robert Güttel

  • 1Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, 45470 Mülheim an der Ruhr, Germany.

Chemistry (Weinheim an Der Bergstrasse, Germany)
|January 6, 2011
PubMed
Summary
This summary is machine-generated.

Stable core-shell catalysts featuring iron oxide nanoparticles within porous silica shells demonstrate high activity and durability for ammonia decomposition. These advanced materials offer excellent performance at high temperatures, making them promising for industrial applications.

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Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
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Published on: June 24, 2022

Area of Science:

  • Materials Science
  • Chemical Engineering
  • Catalysis

Background:

  • Ammonia decomposition is crucial for hydrogen production and nitrogen fixation.
  • Development of stable, high-temperature catalysts is essential for efficient ammonia decomposition.
  • Core-shell nanostructures offer unique properties for catalytic applications.

Purpose of the Study:

  • To synthesize and characterize novel core-shell catalysts for high-temperature ammonia decomposition.
  • To investigate the influence of core size and reaction conditions on catalyst performance.
  • To evaluate the long-term stability and active phases of the catalysts under reaction conditions.

Main Methods:

  • Hydrothermal synthesis of α-Fe(2)O(3) nanoparticles (hematite) with controlled sizes.
  • Coating of hematite nanoparticles with porous silica shells using tetraethylorthosilicate (TEOS) and cetyltetramethylammonium bromide (CTABr).
  • Characterization using TEM, HR-SEM, EDX, XRD, and nitrogen sorption.
  • Ammonia decomposition testing at high temperatures (up to 800°C) with varying parameters.
  • In situ XRD analysis to identify crystalline phases under reaction conditions.

Main Results:

  • Successfully synthesized core-shell catalysts with hematite nanoparticles encapsulated in porous silica shells (20 nm thickness).
  • Achieved high surface areas (~380 m²/g) and stable iron content (10.5–12.2 wt%).
  • Demonstrated high catalytic activity and stability, maintaining ~80% ammonia conversion at 750°C for 33 hours.
  • Identified body-centered iron and FeN(x) as crystalline phases under reaction conditions above 650°C.

Conclusions:

  • The synthesized α-Fe(2)O(3)@SiO(2) core-shell catalysts are highly effective and stable for high-temperature ammonia decomposition.
  • Catalyst performance is influenced by core size and reaction parameters, with optimized structures showing excellent durability.
  • The core-shell design provides a robust platform for fundamental studies of catalytic mechanisms at extreme conditions.