Exceptionally thermally stable, hydrocarbon soluble Ziegler-type Ir(0)(n) nanoparticle catalysts made from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3: Tests of key hypotheses for their unusual stabilization

Date

2013-11-01

Author

Hamdemir, Isil K.
Özkar, Saim
Finke, Richard G.

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

185
views

0
downloads

In recent work we showed that Ziegler-type nanoparticles made from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3 are an unusually thermally stable (>= 30 min at 200 degrees C), hydrocarbon-solvent soluble, high catalytic activity nanoparticle catalyst (I.K. Hamdemir, S. Ozkar, K.-H. Yih, J.E. Mondloch, R.G. Finke, ACS Catal. 2 (2012) 632-641). As such, they are analogous to-and currently the cleanest and best characterized model system for-Ziegler-type nanoparticles made from Co or Ni precatalysts plus AlEt3 which are used industrially to hydrogenate similar to 1.7 x 10(5) metric tons of styrenic block copolymers per year (for a review of the area, see W.M. Alley, I.K. Hamdemir, K.A. Johnson, R.G. Finke, J. Mol. Catal.: A Chem. 315 (2010) 1-27). The key question addressed in the present paper is "What is the nature of the AlEt3-derived stabilizer species?" for the unusually stable and active Ziegler-nanoparticles formed from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3. Specifically tested herein are four primary hypotheses for the AlEt3-derived stabilizer(s) in the Ir(0)(n) Ziegler-nanoparticle system: (i) that the key stabilizer is neutral (i.e., uncharged) aluminum alkyl carboxylates following precedent from the work of Shmidt and Bonnemann; (ii) that the key stabilizer is anionic [AlEt3(O2C8H15)](-); (iii) that a key stabilizer is the AlEt3 (or its derivatives) reacting with the Ir(0)(n) nanoparticle surface; or (iv) that an important AlEt3-derived stabilizer is Al-O-Al containing alkylalumoxanes formed from any water present. The results obtained rule out (ii), but provide strong evidence for (iii), as well as evidence consistent with (i) and (iv), as stabilizers in Ziegler-nanoparticles. A pictorial scheme (Scheme 2) is provided as a working hypothesis for the stabilization mode(s) of Ziegler-nanoparticles and as a way to focus and expedite the needed additional composition and structural studies of Ziegler-nanoparticle stabilizers.

Subject Keywords

Physical and Theoretical Chemistry, Process Chemistry and Technology, Catalysis

URI

https://hdl.handle.net/11511/40428

Journal

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL

DOI

https://doi.org/10.1016/j.molcata.2013.07.005

Collections

Department of Chemistry, Article

Suggestions

OpenMETU
Core

Inverse relation between the catalytic activity and catalyst concentration for the ruthenium(0) nanoparticles supported on xonotlite nanowire in hydrogen generation from the hydrolysis of sodium borohydride Akbayrak, Serdar; Özkar, Saim (Elsevier BV, 2016-12-01) Ruthenium(0) nanoparticles supported on xonotlite nanowire (Ru(0)/X-NW) were prepared by the ion exchange of Rua* ions with Ca2+ ions in the lattice of xonotlite nanowire followed by their reduction with sodium borohydride in aqueous solution at room temperature. Ru(0)/X-NW show high catalytic activity and long life time in hydrogen generation from the hydrolysis of sodium borohydride with a turnover frequency value up to 305 min(-1) and a total turnover number of 63,100 mol H-2/mol Ru in hydrogen generatio...
Novel neutral phosphinite bridged dinuclear ruthenium(II) arene complexes and their catalytic use in transfer hydrogenation of aromatic ketones: X-ray structure of a new Schiff base, N3,N3 '-di-2-hydroxybenzylidene-[2,2 ']bipyridinyl-3,3 '-diamine AYDEMİR, MURAT; DURAP, FEYYAZ; BAYSAL, AKIN; MERİÇ, NERMİN; Buldag, Ayseguel; Guemguem, Bahattin; Özkar, Saim; Yildirim, Leyla Tatar (Elsevier BV, 2010-07-01) A novel Schiff base N3,N3'-di-2-hydroxybenzylidene-[2,2']bipyridinyl-3,3'-diamine, 1 was synthesized from condensation of salicylaldehyde with 3,3'-diamino-2,2'-bipyridine. Reaction of 1 with two equivalents of PPh(2)Cl in the presence of Et(3)N proceeds in toluene to give N3,N3'-di-2-(diphenylphosphino)benzylidene-[2,2']bipyridinyl-3,3'-diamine, 2 in quantitative yield. Ruthenium(II) dimers [Ru(eta(6)-arene)(mu-Cl)]Cl](2) readily react with phosphinite ligand [(Ph(2)PO)(2)-C(24)H(16)N(4)], 2 in toluene at ...
Self-sustained oscillatory behavior of NO+CH4+O-2 reaction over titania-supported Pd catalysts OZKAN, UMIT; KUMTHEKAR, MAHESH; Karakaş, Gürkan (Elsevier BV, 1997-10-01) Self-sustained, regular oscillations were observed in NO + CH4 + O-2 reaction over Pd/TiO2 catalysts at specific temperatures and oxygen concentrations. The oscillatory behavior was investigated combining NO reduction and methane combustion reaction studies with additional catalyst characterization experiments performed under controlled atmospheres. The catalyst was prepared using a wet impregnation technique with Pd-acetate as the precursor for palladium. A fixed-bed, flow reactor system was used to perfor...
Nanoceria supported palladium(0) nanoparticles: Superb catalyst in dehydrogenation of formic acid at room temperature Akbayrak, Serdar; TONBUL, YALÇIN; Özkar, Saim (Elsevier BV, 2017-06-05) Highly efficient dehydrogenation of formic acid (FA) at room temperature was achieved using palladium(0) nanoparticles supported on nanoceria (Pd-0/CeO2) as catalysts. Pd-0/CeO2 was prepared by impregnation of palladium(II) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. Pd((0)/CeO2 was isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The catalytic activity of ...
Palladium(0) nanoparticles supported on polydopamine coated CoFe2O4 as highly active, magnetically isolable and reusable catalyst for hydrogen generation from the hydrolysis of ammonia borane Manna, Joydev; Akbayrak, Serdar; Özkar, Saim (Elsevier BV, 2017-07-05) Palladium(0) nanoparticles supported on cobalt ferrite (Pd degrees/CoFe2O4) are found to be highly active catalyst, providing an unprecedented catalytic activity with a turnover frequency of 290 min(-1) in hydrogen generation from the hydrolysis of ammonia borane at room temperature. However, the initial catalytic activity of Pd degrees/CoFe2O4 catalyst is not preserved after the reuse of the catalyst in hydrolytic dehydrogenation of ammonia borane. The stability of the catalyst is improved by using the pol...

Citation Formats

I. K. Hamdemir, S. Özkar, and R. G. Finke, “Exceptionally thermally stable, hydrocarbon soluble Ziegler-type Ir(0)(n) nanoparticle catalysts made from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3: Tests of key hypotheses for their unusual stabilization,” JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, pp. 333–343, 2013, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/40428.