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  • Author or Editor: Rong Shao x
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Abstract

The catalytic hydrogenation of p-nitrophenol to produce p-aminophenol (PAP) was carried out over the catalyst nickel supported on active carbon (AC). The calcination temperature was one of the most important technical conditions: temperature higher than 450 °C would result in the reduction of NiO to Ni phase by AC and the loss of support. The surface area and nickel dispersion over catalyst decreased obviously after 450 °C calcination temperature because of the loss of support and the Ni phase sintering. Addition of K2O enhanced the alkalinity of the Ni/AC catalyst, and the p-nitrophenol stuff performed rather stronger acidity. Therefore, the level of p-nitrophenol adsorption over Ni/AC catalyst was improved, and the reaction efficiency was enhanced consequently. The p-nitrophenol conversion and PAP selectivity reached 97.7 and 99.3% over Ni–K2O/AC catalyst, respectively. During the process of catalytic hydrogenation, higher PAP selectivity was kept successively. It indicated that no side reactions happened during the catalytic hydrogenation of p-nitrophenol.

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Abstract

The dehydrogenation of isobutane to produce isobutene coupled with reverse water gas shift (RWGS) reaction in the presence of carbon dioxide was investigated over a NiO/γ-Al2O3 catalyst. The results illustrated that the coupling dehydrogenation of isobutane in carbon dioxide over NiO/γ-Al2O3 catalyst is effective, and the NiO/Al2O3 catalyst was modified with deposited carbon by impregnation of alumina with an aqueous solution of Ni(H2NCH2CH2NH2)x (NO3)2. Carbon modification can decrease the total acidity of the NiO/γ-Al2O3 catalyst and enhance the dispersion of NiO active phase. Furthermore, carbon has low acidity and anti-coking performance, so the carbon modification is effective in suppressing the coke formation and side reactions occurrence. Therefore, the catalyst stability and the isobutene selectivity are improved significantly by the carbon modification.

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Abstract  

N,N,N′,N′-tetrahexylsuccinylamide (THSA) was used for the extraction of U(VI) and Th(IV) ions from nitric acid media into n-dodecane. Extraction distribution ratios of U(VI) and Th(IV) as a function of nitric acid concentration, extractant concentration and temperature have been studied. It was found that THSA as a new extractant is superior in some aspects to TBP for extraction of U(VI) and Th(IV). The extraction of nitric acid was also investigated. At low acidity, the main adduct of THSA and HNO3 is THSA·HNO3. THSA·(HNO3)2 and THSA·(HNO3)3 also formed at high acidity. The composition of the species, equilibrium constants and enthalpies of the extraction reactions have also been calculated. The suggested formation of the 1:2:1 ratio of uranyl(VI) ion and the 1:4:2 ratio of thorium(IV) ion, nitrate ion and THSA as the extracted species was further confirmed by the IR spectra of U(VI) and Th(IV) extracts.

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Abstract  

A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium (VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO3). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species.

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Abstract  

The influence of the concentration of nitric, hydrochloric and phosphoric acids, petroleum sulfoxides (PSO), salting-out agent, kind of diluent and temperature on the distribution ratio of U(VI) and Th(IV) has been systematically studied. It is found that the extraction regularity of PSO is similar to that of TBP. The distribution ratio in phosphoric acid is lower, but it increases with the increase of hydrochloric acid concentration and reaches a high value. The U(VI) exhibits the maximum distribution ratio at 3–4 mol/l HNO3. The distribution ratio of U(VI) and Th(IV) increases rapidly in the presence of a salting out agent. The extracted compounds are determined to be UO2(NO3)22PSO and Th(NO3)42PSO. The extraction enthalpies of U(VI) and Th(IV) with PSO were also calculated.

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Abstract  

The extraction of uranium(VI) from nitric acid by N-octanoylpiperidine (OPPD) in toluene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures. The mechanism of extraction is discussed in the light of the results obtained. The extracted species have also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated.

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Abstract  

N,N,N,N-tetrabutylsuccinylamide (TBSA) in a diluent composed of 50% trimethylbenzene (TMB) and 50% kerosene (OK) can extract uranyl (II) ion from nitric acid solution. The results of extraction study suggested the formation of the 121 uranyl (II) ion, nitrate ion and N,N,N,N-tetrabutylsuccinylamide complex as extracted specis. The values of thermodynamic functions have been calculated.

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Abstract  

The extraction of U(VI) from nitric acid solutions with di-(1-methylheptyl) phosphoric acid has been investigated. The dependence on nitric acid concentration, DMHPA concentration and temperature has been considered and the infra-red spectra of extracted species and extractant were recorded. The mechanism of extraction is discussed in the light of the results obtained.

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Abstract  

The partition of uranium(VI) between nitric acid and N,N-dibutyldecanamide (DBDEA) in kerosene has been investigated at various concentrations of nitric acid, extractant and salting-out agent LiNO3. The mechanism of extraction is discussed in the light of the results obtained. The effect of TBP on the extraction of uranium(VI) with DBDEA has also been considered. There is an apparent synergistic effect with these two extractants at low concentration of TBP, however, one sees a decrease in extraction distribution at higher concentration. IR spectra show that there is no apparent interaction between the two kinds of extractants. The stoichiometry of the synergistic extracted species has been determined.

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Abstract  

A new extractant, N-octanoyl-2-methylpiperidine (OMPPD) has been synthesized. The extraction of U(VI) with N-octanoyl-2-methylpiperidine (OMPPD) in nitric acid has been studied. The dependence of the partition reaction of U(VI) on the concentrations of nitric acid, extractant, salting-out agent LiNO3, and temperature has been studied. In the light of the results, the extraction mechanism is discussed. The synergistic extracted complexes may be presented as UO2(NO3)2(OMPPD)2 . The related thermodynamic functions were calculated.

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