Video Experimental Relacionado
Updated: Jul 30, 2025
10:39
Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
Published on: August 23, 2018
7.9K
Fomento de la renovación del sitio activo en catalizadores de metástasis de olefinas heterogéneas
Terry Z H Gani1,2, Zachariah J Berkson2, Ran Zhu1
1Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
Nature
|May 17, 2023
Resumen
Los investigadores descubrieron un nuevo ciclo dinámico en la metástasis de olefinas sobre los catalizadores de óxido de tungsteno. La manipulación de este ciclo con olefinas promotoras aumenta significativamente las tasas de producción de propileno, mejorando la viabilidad industrial.
Área de la Ciencia:
- Catálisis
- Ingeniería Química
- Ciencias de los materiales
Sus antecedentes:
- La metátesis de olefinas catalizada de manera heterogénea es vital para las industrias químicas.
- La producción de propileno a través de la metástasis cruzada de etileno y 2-butenos aborda la escasez de materias primas.
- Las ambigüedades en los mecanismos de metástasis impiden el desarrollo de procesos industriales.
Objetivo del estudio:
- Para aclarar los detalles mecánicos de la metatesis de propileno sobre los catalizadores de WOx/SiO2.
- Identificar los factores que limitan la actividad del catalizador y la eficiencia del proceso.
- Desarrollar estrategias para mejorar las tasas de metástasis de olefinas para aplicaciones industriales.
Principales métodos:
- Medidas cinéticas rigurosas de la metástasis del propileno.
- Estudios espectroscópicos con modelos y catalizadores industriales de WOx/SiO2.
- Investigación del comportamiento del catalizador en condiciones variables y con olefinas promotoras.
Principales resultados:
- Identificación de un nuevo ciclo dinámico de renovación y decaimiento del sitio que implica transferencias de protones.
- Demostrar que este ciclo funciona simultáneamente con el ciclo clásico de Chauvin.
- Aumento de hasta 30 veces en las tasas de metástasis de propileno en estado estacionario a 250 °C mediante la manipulación del ciclo con olefinas promotoras.
- Mejoras observadas en la actividad y reducción de los requisitos de temperatura para los catalizadores MoOx/SiO2.
Conclusiones:
- El ciclo dinámico recién identificado es un factor clave en la metátesis de olefinas sobre WOx/SiO2.
- La manipulación estratégica de este ciclo ofrece una vía para mejorar significativamente los procesos de metástasis industrial.
- Este enfoque muestra potencial para una aplicación más amplia en la catálisis, abordando los principales obstáculos industriales.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:13Olefin Metathesis Polymerization: Overview
2.2K
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists...
2.2K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.4K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.4K
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
2.0K
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
2.0K
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
2.7K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
2.7K
02:50Catalysis
27.1K
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.
27.1K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.2K
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...
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...
12.2K