Papers by Keyword: Rhodium

Abstract: It was found that the surfaces of rhodium and platinum electrodes with polarization by direct current in 12 M hydrochloric acid solution are completely covered with oxygen atoms at a potential of +0.68 V (relative to the reference hydrogen electrode), and its increase rate is 10–90 mV/s.

Abstract: In the present work, the impact of the rhodium deposition on the thermal stability of ceria-based catalysts was studied. The samples were prepared by an incipient wetness impregnation of the support with aqueous solution of rhodium nitrate. The loading of Rh was 0.1 and 1 wt.%. The textural characteristics of the samples were examined by a low-temperature nitrogen adsorption. It was shown that the addition of rhodium intensifies the process of ceria agglomeration, which leads to the lower values of specific surface area along with increased average pore diameter after the aging at 1000 °C. Stability of the catalysts was investigated by means of a prompt thermal aging procedure. The high-loaded catalyst (1 wt.% Rh/CeO₂) was more active than the 0.1 wt.% Rh/CeO₂ sample, while the stability of both the catalysts was excellent. It should be emphasized that the alumina-based reference samples with the similar rhodium loading were significantly less active and poorly stable.

Abstract: In this article, the electrochemical properties of elemental sulfur dissolved in alkaline solution has been studied for the first time using the method of removing the anodic and anodic-cathodic potentiodynamic polarization curves on rhodium electrodes. The influences of different parameters for oxidation process of elemental sulfur, namely sulfur component in electrolyte concentration, scan rate and temperature were investigated. The resulting polarogram presented in oxidation reaction of polysulfide ions to elemental sulfur process. This shows that polysulfide-ions in electrolyte at cathodic polarization was restored to monosulfide, and monosulfide –ions oxidized to elemental sulfur. The effective activation energy was calculated which equals 13,67 Kj/mol, indicating the oxidation reaction of sulfur occurred in diffusion mode.

Abstract: A novel method for the determination of rhodium in waste thiourea rhodium samples was established by inductively coupled plasma optical emission spectrometry after samples digested by Teflon pressure digestion vessel with aqua regia. Such experiment conditions were investigated as the influence of sample dissolution methods, digestion time, digestion temperature and interfering ions on the determination. Under the optimized conditions, the limit of detection (LODs) of Rh for tested solution was 9 ng mL^-1. The relative standard deviations (RSDs) for Rh was 1.98 % (C_Rh = 1 mg L^-1, n = 7). The linear range of calibration graph for Rh was 0 ~ 150.00 mg L^-1. The proposed method was applied to determine the practical samples with good recoveries and satisfactory results.

Abstract: A novel method for the determination of rhodium in rhodium-loaded carbon catalyst samples was established by inductively coupled plasma atomic emission spectrometry after samples digested by microwave oven with aqua regia. Such experiment conditions were investigated as the influence of sample digestion methods, digestion time, digestion temperature and interfering ions on the determination. Under the optimized conditions, the limits of detection (LODs) of Rh for tested solutions were 9 ng mL^-1. The relative standard deviations (RSDs) for Rh were 2.11 (C_Rh = 1 mg L^-1, n = 7). The linear ranges of calibration graphs for Rh were 0 ~ 150.00 mg L^-1. The proposed method was applied to determine the practical samples with good recoveries and satisfactory results.

Abstract: A novel method for the determination of rhodium in rhodium octanoate organic waste liquid samples was established by inductively coupled plasma atomic emission spectrometry after samples digested by Teflon pressure digestion vessel with aqua regia. Such experiment conditions were investigated as the influence of sample dissolution methods, digestion time, digestion temperature and interfering ions on the determination. Under the optimized conditions, the linear range of calibration graph for Rh was 0 ~ 150.00 mg L^-1, and the recovery was 96.20% ~ 102.36%. The relative standard deviation (RSDs) for Rh was 1.75 %. The proposed method was applied to determine the same samples with atomic absorption spectrometry with the results consistently, which is suitable for the determination of rhodium in rhodium octanoate organic waste liquid samples.

Abstract: A novel method for the determination of rhodium in waste rhodium-loaded carbon catalyst samples was established by inductively coupled plasma atomic emission spectrometry after samples digested by Teflon pressure digestion vessel with aqua regia. Such experiment conditions were investigated as the influence of sample dissolution methods, digestion time, digestion temperature and interfering ions on the determination. The results indicated that the digestion effect was optimum with samples digested 8 hour at 180 ^°C. Al, Fe, Mg, Ca and Si in samples had no effect on the determination of rhodium. Experiment indicated rhodium concentration within the range of 0 ~ 150 mg L^-1 had a linear relation with emission intensity. The recovery was 99.20% ~ 100.73 %, and the relative standard deviation was 1.8 %. A satisfactory result was obtained when applying the proposed method in the practical sample.

Abstract: The catalytic hydrodechlorination of 4-chlorophenol promoted by different hydrophilic catalysts based on Pt and Rh on aluminum oxy-hydroxide (AlO(OH)) was carried out in water at 30 °C under atmospheric pressure. Among these catalysts, Rh/AlO(OH) was effective in the removal of 4-chlorophenol, with phenol, cyclohexanone, and cyclohexanol identified as reaction products. The Rh/AlO(OH) catalyst showed excellent hydrodechlorination performance in water than organic solvents, 4-cholophenol was completely dechlorinated within 60 min in water in contrast to less than 26 % in organic solvents. Furthermore, the Rh/AlO(OH) catalyst can be recycled four times without any inorganic and organic additives.