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Kantcheva, Margarita; Sayan, Şafak

doi:10.1023/a:1019082218590

Cited by 57 publications

(46 citation statements)

References 67 publications

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“…In addition, the formation of subsurface hydrogen species has been reported [11]. CO gives strongly corrosive chemisorption [12], thus precluding any possibility of using it as probe molecule.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of Ru/C catalysts for ammonia synthesis by oxygen chemisorption

Rossetti

Pernicone

Forni

2003

Applied Catalysis A: General

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A standard chemisorption procedure has been set up for the determination of Ru dispersion in Ru/C catalysts. Pulse chemisorption of oxygen was carried out at 0°C, after having proved that no corrosive chemisorption phenomena are present. An average chemisorption stoichiometry Ru*/O = 1.0 was experimentally determined through measurements on Ru black. The procedure was applied to the investigation of promoted and unpromoted Ru/C catalysts for ammonia synthesis, supported on two different carbon supports. The main factor influencing Ru dispersion showed to be Ru loading, while the addition of even large amounts of Ba-Cs-K promoters has practically no influence. It is also briefly discussed how such results can help in elucidating several aspects of the behaviour of Ru/C as catalyst for ammonia synthesis.

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Section: Introductionmentioning

confidence: 99%

Characterisation of Ru/C catalysts for ammonia synthesis by oxygen chemisorption

Rossetti

Pernicone

Forni

2003

Applied Catalysis A: General

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“…7,8 On unwashed Ru/Al 2 O 3 , HF1 and HF2 were clearly observed, suggesting that the residual Cl retarded the reduction of surface Ru atoms. After washing with aqueous ammonia, the intensities of HF1 and HF2 decreased significantly.…”

Section: ¹1mentioning

confidence: 97%

Effects of Removing Residual Chlorine on the Hydrogenation of Aromatic Hydrocarbons over Supported Ru Catalysts

et al. 2009

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Hydrogenation activity of aromatic hydrocarbons was remarkably increased when the residual chlorine on Ru/Al 2 O 3 and Ru/SiO 2 was removed by washing. On the basis of FT-IR spectra in the CO region, a site active for hydrogenation reactions was created by removal of the residual chlorine.Supported Ru catalysts have been widely studied because they can be used in a variety of practical applications. 1 The effect of residual chlorine has been reported. For instance, Narita et al. 2,3 have reported that the adsorption of CO and H 2 was inhibited by residual Cl, and Mazzieri et al. 4 have reported that residual Cl inhibits the reduction of Ru in Ru/Al 2 O 3 . In this study, we tried to completely remove Cl from Ru/Al 2 O 3 and Ru/SiO 2 and found a remarkable enhancement in the hydrogenation activity of naphthalene and toluene.The catalysts 2 wt % Ru/Al 2 O 3 and 2 wt % Ru/SiO 2 were prepared by using an impregnation method with RuCl 3 ¢ nH 2 O (n = 2.2, Wako Pure Chem.). Al 2 O 3 (Neobead GB-45, Mizusawa Industrial Chem.) and SiO 2 (Silbead, Mizusawa Industrial Chem.) were used as supports. The support granules (<100 mesh) were immersed in a solution of RuCl 3 , and water was removed under vacuum. The granules were then kept at 403 K in air overnight. The catalysts were reduced in flowing hydrogen at 673 K for 5 h and then washed with hot deionized water or aqueous ammonia (0.01 mol L ¹1) using a volume of 500 mL g-cat ¹1. Hydrogenation of naphthalene and toluene was performed in a 100-mL stainless steel autoclave equipped with a stirrer. Because the naphthalene (Kanto Chem.) contained a considerable amount of benzothiophene as an impurity, it was purified using a Ni catalyst (C-28, Süd Chemie Catalyst) in 0.1 MPa of hydrogen at 373 K. The purified naphthalene (1.00 g, 7.8 mmol) or toluene (0.719 g, 7.8 mmol) was dissolved in n-tridecane (40 mL) as a solvent. The catalyst (0.10.2 g) was reduced at 673 K for 1 h in a Pyrex tube and then transferred to the autoclave for the hydrogenation reaction. Hydrogenation reactions were carried out in the temperature range of 273303 K for 1 h with an initial H 2 pressure of 0.98 MPa and agitation at 1000 rpm. The reaction products were analyzed using FID gas chromatography. The amount of metal atoms exposed was estimated by analyzing the amount of adsorbed CO using a pulse adsorption apparatus (BP-1, Ohkura Riken). The amounts of Ru loading and remaining Cl were determined by using X-ray fluorescence (XRF). FT-IR spectra were acquired on a Jasco FT-IR-350 at room temperature after exposing the catalysts to CO (20 Torr) at room temperature for 20 min and then evacuating at room temperature for 30 min.The amounts of Ru loading, remaining Cl, and adsorbed CO before and after washing are listed in Table 1. Before washing, Ru/Al 2 O 3 contained about five times more Cl than Ru/SiO 2 did, suggesting that the alumina support had an affinity toward Cl, which is in agreement with the literature.3,5 Washing with deionized water gradually lowered the amount of Cl. However, a considerable ...

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“…The formation of these partially oxidized Ru species has been related to the presence of OH groups on the Al 2 O 3 support [39]. The presence of residual NO species (of the metal salt precursor) at the surface of these catalysts as stabilizing agents of partially oxidized Ru species, previously suggested for reduced but non-calcined Ru catalysts [42,43], can be neglected, as these samples were calcined at 773 K. The band that appears as a shoulder at a wavenumber of ca. 2045 cm À1 has been ascribed, generally, to linearly adsorbed CO over Ru 0 [24,33,[39][40][41].…”

Section: Co Adsorption Calorimetric Measurementsmentioning

confidence: 97%

Effect of the metal precursor on the surface site distribution of Al2O3-supported Ru catalysts: catalytic effects on the n-butane/H2 test

Maroto-Valiente

Cerro-Alarcón

Guerrero-Ruı́z

et al. 2005

Applied Catalysis A: General

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Untitled

Cited by 57 publications

References 67 publications

Characterisation of Ru/C catalysts for ammonia synthesis by oxygen chemisorption

Characterisation of Ru/C catalysts for ammonia synthesis by oxygen chemisorption

Effects of Removing Residual Chlorine on the Hydrogenation of Aromatic Hydrocarbons over Supported Ru Catalysts

Effect of the metal precursor on the surface site distribution of Al2O3-supported Ru catalysts: catalytic effects on the n-butane/H2 test

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