An ESR study of zeolite-supported ruthenium hydrodenitrogenation catalyst

Oliver, Stuart W.; Smith, Thomas D.; Pilbrow, John R.; Harvey, T. G.; Matheson, Trevor W.; Pratt, Kerry C.

doi:10.1016/s0020-1693(00)88052-4

Cited by 7 publications

(3 citation statements)

References 5 publications

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“…The 14 N hyperfine coupling used here is in line with what was used to simulate ligand radical contributions for the Fe2a* and Fe4a EPR spectra. The g values used to model the background are not fit well in this simulation because contributions are only clearly resolved at the high- and low-field edges of the spectrum, but they are commensurate with values reported for octahedral Ru(III) complexes isolated in zeolites . The spectrum shown in Figure a represents the opposite extreme with 90% of the amplitude coming from a Ru(III)-centered S = 1/2 paramagnetic center with g values of 2.06, 2.01, and 1.97.…”

Section: Resultsmentioning

confidence: 50%

“…The g values used to model the background are not fit well in this simulation because contributions are only clearly resolved at the high-and low-field edges of the spectrum, but they are commensurate with values reported for octahedral Ru(III) complexes isolated in zeolites. 69 The spectrum shown in Figure 8a represents the opposite extreme with 90% of the amplitude coming from a Ru(III)-centered S = 1/2 paramagnetic center with g values of 2.06, 2.01, and 1.97. The remaining 10% is assigned to an imide radical characterized by g = 2.007 and an 14 N hyperfine coupling of A iso = 4.0 MHz and A dip = 80.6 MHz.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

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Electronic and Structural Comparisons between Iron(II/III) and Ruthenium(II/III) Imide Analogs

et al. 2019

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To examine structural and electronic differences between iron and ruthenium imido complexes, a series of compounds was prepared with different phosphine basal sets. The starting material for the ruthenium complexes was Ru(NAr/Ar*)(PMe 3 ) 3 (Ru1/Ru1*), where Ar = 2,6-( i Pr) 2 C 6 H 3 and Ar* = 2,4,6-( i Pr) 3 C 6 H 2 , which were prepared from cis-RuCl 2 (PMe 3 ) 4 and 2 equiv of LiNHAr/Ar*. The starting materials for the iron complexes were the analogous Fe(NAr/Ar*)(PMe 3 ) 3 species (Fe1/Fe1*), which were not isolated but could be generated in situ from FeCl 2 , PMe 3 , and LiNHAr/Ar*. With both iron and ruthenium, the PMe 3 starting materials underwent phosphine replacement with chelating ligands to give new group 8 imido complexes in the +2 oxidation state. Addition of 1,2-bis(diphenylphosphino)ethane (dppe) to M1/M1* gave Ru(NAr/Ar*)(PMe 3 )(dppe) and Fe(NAr/ Ar*)(PMe 3 )(dppe). Addition of 1,2-bis(dimethylphosphino)ethane (dmpe) provided Ru(NAr/Ar*)(dmpe) 2 . A triphos ligand, {P(Me) 2 CH 2 } 3 Si t Bu ( t P 3 ), was also examined. Addition of t P 3 to Fe1 provided Fe(NAr)( t P 3 ) (Fe4), but a similar reaction with Ru1 only gave intractable materials. Oxidation of Fe4 with AgSbF 6 gave {Fe(NAr)( t P 3 )} + SbF 6 − (Fe4a). Oxidation of Ru2 with AgSbF 6 gave the unstable cation {Ru(NAr)(PMe 3 )(dppe)} + , which dimerized in the presence of acetonitrile via C−C bond formation at the aryl group C4 positions, affording {Ru(NAr)(PMe 3 )(NCMe)(dppe)} 2 + . This suggested that there was substantial radical character in the imide π system on oxidation and that an aromatic group substituted at the 4-position might provide greater stability. The cations {Fe(NAr*)(PMe 3 )(dppe)} + (Fe2a*), {Ru(NAr*)(PMe 3 )(dppe)} + (Ru2a*), and Fe4a were examined by EPR spectroscopy, which suggested differences in electronic structure depending on the metal and ligand set. CASPT2 calculations on model systems for Ru2a* and Fe2a* suggested that the large differences in electronic structure are related to the energy gap between the π-antibonding HOMO and the π-bonding HOMO-1. Both the geometry of the phosphines, which is slightly different between the iron and ruthenium analogs, and the metal center seem to contribute to this energetic difference.

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Section: Resultsmentioning

confidence: 50%

Section: Inorganic Chemistrymentioning

confidence: 99%

Electronic and Structural Comparisons between Iron(II/III) and Ruthenium(II/III) Imide Analogs

et al. 2019

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“…The ESR technique was used to characterize, ruthenium clusters on mesoporous supports [21], zeolite supported ruthenium [22] and Ru/silica and Ru/graphite catalysts [23].…”

Section: Introductionmentioning

confidence: 99%

ESR Investigation of Active Sites in Ru/CeO2 Solids

et al. 2016

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Two Ru/CeO 2 catalysts with Ru loadings of 1.65 and 5 wt% were prepared by wet impregnation. The adsorption of propylene or toluene led to two different ESR signals corresponding to two different catalytic sites. These two sites are present among the well dispersed ruthenium oxide species that reduce at *74°C. One site is un-reactive unless activated to remove adsorbed water while the second site is reactive at room temperature. Both sites are easily regenerated under oxidative atmosphere at 200°C. These two sites are optimally obtained for calcination temperatures in the 500-600°C interval and a Ru loading of 1.65 wt%. For Ru5Ce, the same reactive sites are present along with agglomerated ruthenium oxide species that are less reactive in oxidation reactions. Graphical Abstract2500 2750 3000 3250 3500 3750 4000 S 3

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Selectivity of Y‐Zeolite and Alumina Supported Ruthenium Sulphide in Hydrodesulfurization of Thiophene

Gőbölös

Lacroix

Decamp

et al. 1991

Bulletin des Soc Chimique

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INTRODUCTIONIt has been found that ruthenium sulphide, either unsupported [I, 21 or supported by carbon [3, 61, is one of the most effective systems for the hydrodesulphurization (HDS) of thiophene [3-51, benzothiophene [6] and dibenzothiophene [I] and hydrogenation of biphenyl [2]. In addition, ruthenium sulphide showed outstanding activity in the hydrodenitrogenation (HDN) of quinoline [7-91, decahydroquinoline [lo] and pyridine [5, 8, 111. However, there is a large discrepancy within the literature concerning the performance of alumina supported ruthenium in hydrotreating reactions. It has been observed that alumina-supported ruthenium samples exhibited lower activity as HDS or as HDN catalysts than molybdenum-based sample [7,12, 131. Nevertheless, Kuo et al. [13, 141 and De Los Reyes et al. [15, 161 demonstrated the importance of the sulphidation process in such systems, and that efficient Ru/Al2O3 sulphide catalysts could be obtained after an activation using H2S or a H2S/N2 gas mixture, respectively. It is noteworthy, that alumina-supported Ru-Mo catalyst has also been investigated in HDS [17, 181, HDN [18, 191 and hydrodeoxygenation [20] reactions.Despite the numerous studies performed on ruthenium-containing hydrotreatment catalysts, little is known about the hydrodesulphurization activity and selectivity of Y-zeolite and alumina-supported sulphided ruthenium species. In view of the earlier studies it was of interest to investigate the role of the support, the type of ruthenium precursor compound and the sulphidation step in determining the catalyst performance. In this papel. the results of the HDS of thiophene on Nay-, HY-and KY-zeolite and alumina supported ruthenium catalysts will be given. The selectivities of the catalysts towards butenes, n-butane, CI-C3 and iC4 hydrocarbons will be interpreted in relation to the sulphidation procedure and the acid strength of the support. The activities, the selectivities and the deactivation properties of the ruthenium-containing catalysts will be compared with those of Mo/Al2O3 and commercial NiMo/A1203.

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An ESR study of zeolite-supported ruthenium hydrodenitrogenation catalyst

Cited by 7 publications

References 5 publications

Electronic and Structural Comparisons between Iron(II/III) and Ruthenium(II/III) Imide Analogs

Electronic and Structural Comparisons between Iron(II/III) and Ruthenium(II/III) Imide Analogs

ESR Investigation of Active Sites in Ru/CeO2 Solids

Selectivity of Y‐Zeolite and Alumina Supported Ruthenium Sulphide in Hydrodesulfurization of Thiophene

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