Video Experimental Relacionado
Updated: May 31, 2026
09:05
Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials
Published on: May 15, 2015
El efecto de la presión parcial de H2 sobre la progresión de la reacción y la reversibilidad de los sistemas de
Tobias E C Price1, David M Grant, David Weston
1Energy and Sustainability Research Division, Engineering Faculty, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
Journal of the American Chemical Society
|July 16, 2011
Resumen
La presión parcial del hidrógeno tiene un impacto significativo en el borohidruro de litio:descomposición del hidruro de magnesio. Las bajas presiones hacen que las aleaciones formen LiH y Mg al enfriarse, lo que afecta la reversibilidad y las mediciones de liberación de hidrógeno.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Ingeniería Química Ingeniería Química.
- Almacenamiento de hidrógeno almacenamiento de hidrógeno.
Sus antecedentes:
- Se sabe que la vía de descomposición de los sistemas LiBH(4):MgH(2) difiere en el vacío frente a la presión de hidrógeno.
- Estudios anteriores no han investigado la sensibilidad de este sistema de hidrógeno multicomponente a bajas presiones parciales de hidrógeno.
Objetivo del estudio:
- Para investigar el efecto de las bajas presiones parciales de hidrógeno en la descomposición de los sistemas LiBH(4):MgH(2).
- Comprender la influencia de las condiciones de vacío en los productos de reacción y la reversibilidad.
Principales métodos:
- Difracción de neutrones en polvo in situ (utilizando deutéridos) y difracción de rayos X.
- Variación controlada de las presiones parciales de hidrógeno utilizando diferentes sistemas de vacío.
Principales resultados:
- Todas las muestras se descomponen para formar aleaciones de Li-Mg, independientemente del sistema de vacío o la estequiometría.
- Al enfriarse, estas aleaciones exhibieron inestabilidad de fase y reaccionaron para formar LiH y Mg, excepto bajo las condiciones de vacío de mayor eficiencia (presiones de base más bajas).
- La cantidad aparente de hidrógeno desarrollada en experimentos ex situ se ve afectada por las condiciones dinámicas del vacío.
Conclusiones:
- La descomposición y la posterior estabilidad del producto de LiBH ((4):MgH ((2) son sensibles a bajas presiones parciales de hidrógeno.
- Las condiciones de vacío incoherentes pueden conducir a resultados irreproducibles en estudios de hidruro multicomponente.
- La formación de una capa de hidruro pasivante en muestras ricas en litio dificulta la hidrogenación, lo que explica las diferencias en la reversibilidad reportada.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:19Acid Halides to Alcohols: LiAlH4 Reduction
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
03:12Chemical Stoichiometry and Gases: Using Ideal Gas Law to Determine Moles
Chemical stoichiometry describes the quantitative relationships between reactants and products in chemical reactions.
03:40Hess's Law
There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.
04:02Weak Acid Solutions
Few compounds act as strong acids. A far greater number of compounds behave as weak acids and only partially react with water, leaving a large majority of dissolved molecules in their original form and generating a relatively small amount of hydronium ions. Weak acids are commonly encountered in nature, being the substances partly responsible for the tangy taste of citrus fruits, the stinging sensation of insect bites, and the unpleasant smells associated with body odor. A familiar example of a...
01:29Chain Reactions
Chain reactions involve highly reactive transient species, such as atoms or free radicals, as intermediates. These intermediates facilitate rapid reactions over an extended period. The process includes a series of steps: a reactive intermediate is consumed, reactants are converted to products, and the intermediate is regenerated. This cycle enables continuous repetition, amplifying the production of products with a small amount of intermediate. Chain reactions often utilize free radicals as...
01:17Esters to Alcohols: Hydride Reductions
Esters are reduced to primary alcohols when treated with a strong reducing agent like lithium aluminum hydride. The reaction requires two equivalents of the reducing agent and proceeds via an aldehyde intermediate.
Lithium aluminum hydride is a source of hydride ions and functions as a nucleophile. The mechanism proceeds in three steps. Firstly, the nucleophilic hydride ion attacks the carbonyl carbon of the ester to form a tetrahedral intermediate. Subsequently, the carbonyl group re-forms,...
Lithium aluminum hydride is a source of hydride ions and functions as a nucleophile. The mechanism proceeds in three steps. Firstly, the nucleophilic hydride ion attacks the carbonyl carbon of the ester to form a tetrahedral intermediate. Subsequently, the carbonyl group re-forms,...