Video Experimental Relacionado

Updated: Apr 27, 2026

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Published on: June 24, 2022

Cinética y mecanismo dramáticamente diferentes en las interfaces sólido / líquido y sólido / gas para la oxidación

Hailiang Wang¹, Andras Sapi, Christopher M Thompson

¹Department of Chemistry, University of California , Berkeley, California 94720, United States.

Journal of the American Chemical Society

|July 4, 2014

Resumen

Los catalizadores de nanopartículas de platino muestran una mayor actividad para la oxidación del isopropanol con partículas de mayor tamaño en las fases líquida y gaseosa. Los mecanismos de reacción difieren significativamente entre las dos fases.

Área de la Ciencia:

La catálisis heterogénea.
Ciencia de los nanomateriales ciencia de los nanomateriales.
Química de las superficies.

Sus antecedentes:

Las nanopartículas de platino (Pt NPs) son catalizadores cruciales.
Comprender la actividad catalítica dependiente del tamaño es clave.
La oxidación del isopropanol es una reacción modelo para el estudio de los mecanismos catalíticos.

Objetivo del estudio:

Para investigar la influencia del tamaño de las nanopartículas de platino en la oxidación del isopropanol.
Para comparar el rendimiento catalítico en las fases de líquido y gas.
Para dilucidar los mecanismos de reacción utilizando métodos cinéticos y espectroscópicos.

Principales métodos:

Síntesis de nanopartículas de platino con tamaños controlados (2-8 nm).
Estudios de la reacción de oxidación del isopropanol en las fases líquida y gaseosa a 60 °C.
Espectroscopia vibratoria de generación de frecuencia de suma (SFG-VS) y cálculos computacionales.

Principales resultados:

La actividad catalítica aumenta con el tamaño de Pt NP en ambas fases.
La reacción en fase gaseosa es ~100 veces más rápida que la en fase líquida.
La energía de activación de la fase gaseosa disminuye con el tamaño de NP; la fase líquida es insensible al tamaño.
El agua promueve la fase líquida pero inhibe las reacciones de la fase gaseosa.

Conclusiones:

Existen mecanismos de reacción distintos para las fases líquida y gaseosa.
Los mecanismos se correlacionan con diferentes orientaciones del isopropanol adsorbido.
El tamaño y la fase de Pt NP afectan significativamente la eficiencia y el mecanismo de oxidación del isopropanol.

Más Videos Relacionados

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

Published on: July 18, 2017

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

Published on: April 10, 2019

Videos de Conceptos Relacionados

Heterogeneous Catalysis

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...

Catalysis

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.

Introduction to Mechanisms of Enzyme Catalysis

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes...

Introduction to Mechanisms of Enzyme Catalysis

Introduction to Mechanisms of Enzyme Catalysis

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

Reduction of Alkenes: Catalytic Hydrogenation

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...