Structure Studies on Chromium—Aluminum Oxide and Related Catalyst Systems

1947 ◽  
Vol 69 (11) ◽  
pp. 2698-2702 ◽  
Author(s):  
Robert P. Eischens ◽  
P. W. Selwood
Keyword(s):  
Aluminum Oxide ◽  
Catalyst Systems

Advances of Chromium(III)-Based Catalysts with Multidentate Heteroatomic Ligands for 1-Hexene Production

2011 ◽  
Vol 317-319 ◽  
pp. 1797-1800 ◽  
Author(s):  
Ya Zhen Wang ◽  
Chuan Feng Yang ◽  
Jie Chen
Keyword(s):  
Aluminum Oxide ◽  
High Activity ◽  
Commercial Application ◽  
Ligand Structure ◽  
Ethylene Trimerization ◽  
Commercial Process ◽  
Catalyst Systems ◽  
Heteroatomic Ligands ◽  
Nitrogen Phosphorus

According to the various multidentate heteroatomic ligands(based oxygen,nitrogen, phosphorus,mixed N and P,mixed N and S donors, composition, activity and overall selectivity to 1-hexene of chromium-based trimerization catalysts were reviewed. Commercial application foreground of these catalyst systems was also expected.It was found that effect of ligand structure on activity and selectivity for ethylene trimerization was the most predominant.The PNP （(Ph2P)2N(cyclopentyl)）ligands were prepared using inexpensive reagents and gave the corresponding complexes in high yields.Due to the inexpensive ligands coupled with low MAO （methyl aluminum oxide）requirements and high activity and selectivity of these systems, this has positive implication for a commercial process to 1-hexene.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

A New Computational Interface for Catalysis

2019 ◽  
Author(s):  
Pavlo Kravchenko ◽  
Craig Plaisance ◽  
David Hibbitts
Keyword(s):  
Zeolite Catalyst ◽  
Metal Ceramic ◽  
Catalyst Systems ◽  
Computational Catalysis

This manuscript outlines the utility and power of our computational catalysis interface. This interface has been developed by our group and used extensively to study metal, ceramic, and zeolite catalyst systems.

Employing Exfoliated Graphite as Novel Support Material for Heterogeneous Model Catalysts

2019 ◽  
Author(s):  
Moritz Wolf ◽  
Nico Fischer ◽  
Michael Claeys
Keyword(s):  
Surface Area ◽  
Graphite Powder ◽  
Model Catalysts ◽  
Model Systems ◽  
Exfoliated Graphite ◽  
Support Material ◽  
Heterogeneous Model ◽  
Support Materials ◽  
Metal Support Interaction ◽  
Catalyst Systems

<p>The inert nature of graphitic samples allows for characterisation of rather isolated supported nanoparticles in model catalysts, as long as sufficiently large inter-particle distances are obtained. However, the low surface area of graphite and the little interaction with nanoparticles result in a challenging application of conventional preparation routes in practice. In the present study, a set of graphitic carbon materials was characterised in order to identify potential support materials for the preparation of model catalyst systems. Various sizes of well-defined Co<sub>3</sub>O<sub>4</sub> nanoparticles were synthesised separately and supported onto exfoliated graphite powder, that is graphite after solvent-assisted exfoliation <i>via</i> ultrasonication resulting in thinner flakes with increased specific surface area. The developed model catalysts are ideally suited for sintering studies of isolated nano-sized cobaltous particles as the graphitic support material does not provide distinct metal-support interaction. Furthermore, the differently sized cobaltous particles in the various model systems render possible studies on structural dependencies of activity, selectivity, and deactivation in cobalt oxide or cobalt catalysed reactions.</p>

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