Cupric oxide （CuO） and copper-cuprous oxide （Cu-Cu2O） nanoparticles were prepared by a simple hydrothermal method for the synthesis of diethyi carbonate （DEC） from ethanol. During these syntheses, varying NaOH a...Cupric oxide （CuO） and copper-cuprous oxide （Cu-Cu2O） nanoparticles were prepared by a simple hydrothermal method for the synthesis of diethyi carbonate （DEC） from ethanol. During these syntheses, varying NaOH and glucose concentrations were applied to explore and pinpoint the active species. It was found that PdCl2/CuO and PdCI2/Cu-Cu2O both catalysts exhibited good thermal stability and morphology. The results of catalytic tests showed that the catalysts prepared with 5 mol/L NaOH show superior catalytic performances because of their lower extent of agglomeration. It is noteworthy that the PdC12/Cu-Cu2O catalysts were the most active, especially the PdCl2/Cu-Cu2O catalyst prepared with 10 mmol glucose and having a higher Cu2O concentration. In Pd（ll）-Cu（II） （PdCl2/CuO） catalysts, there is an induction period, during which Pd（II） is reduced to Pd（0）, that must occur prior to electron transfer between Pd and Cu, and this can slow the catalytic reaction. To further pinpoint the active species, PdCl2/Cu-Cu2O catalysts with different Cu2O contents were prepared by controlling the dosages of glucose. The maximum DEC yield obtained with these catalysts was 151.9 mg.g-1.h-1, corresponding to an ethanol conversion of 7.2% and 97.9% DEC selectivity on an ethanol basis. Therefore, it was concluded that Cu＋ was the active species in this catalytic system, possibly because a higher proportion of Cu＋ reduces the Pd2＋ concentration and limits the CO oxidation side reaction, thus increasing DEC selectivity. In addition, Cu＋ promotes electron transfer between Pd and Cu without an induction period, which could also promote the catalytic activity.展开更多
In order to improve the yield and stability of ferrate in solution, dissolved Fe(Ⅵ) prepared with NaOH and KOH respectively was compared in this study. The results showed that KOH is more suitable than NaOH for the p...In order to improve the yield and stability of ferrate in solution, dissolved Fe(Ⅵ) prepared with NaOH and KOH respectively was compared in this study. The results showed that KOH is more suitable than NaOH for the preparation of dissolved Fe(Ⅵ) at temperature over 50 ℃. It is found that the dissolved Fe(Ⅵ) prepared with KOH increases quickly at first, and then slowly with the increasing concentrations of OH-and ClO-, while it increases rapidly at first and then decreases rapidly with the increasing dosage of Fe(NO3)3·9H2O. These results are different from that prepared with NaOH. It can be explained that solid K2FeO4 salts can be formed in KOH solution, and it will lower the Fe(Ⅵ) concentration, counteract the decomposition of Fe(Ⅵ), and improve the yield of Fe(Ⅵ). The maximum ferrate concentration is 0.163 mol/L obtained by 100 g/L Fe(NO3)3·9H2O and 6.16 mol/L KOH at 65 ℃. The stability of Fe(VI) is greatly improved due to the hypochlorite existed in the dissolved ferrate, and only 24% Fe(Ⅵ) has been decomposed after 16 d for 1 mmol/L Fe(Ⅵ) at 25 ℃.展开更多
基金supported by the National Natural Science Foundation of China(21106054)~~
文摘Cupric oxide （CuO） and copper-cuprous oxide （Cu-Cu2O） nanoparticles were prepared by a simple hydrothermal method for the synthesis of diethyi carbonate （DEC） from ethanol. During these syntheses, varying NaOH and glucose concentrations were applied to explore and pinpoint the active species. It was found that PdCl2/CuO and PdCI2/Cu-Cu2O both catalysts exhibited good thermal stability and morphology. The results of catalytic tests showed that the catalysts prepared with 5 mol/L NaOH show superior catalytic performances because of their lower extent of agglomeration. It is noteworthy that the PdC12/Cu-Cu2O catalysts were the most active, especially the PdCl2/Cu-Cu2O catalyst prepared with 10 mmol glucose and having a higher Cu2O concentration. In Pd（ll）-Cu（II） （PdCl2/CuO） catalysts, there is an induction period, during which Pd（II） is reduced to Pd（0）, that must occur prior to electron transfer between Pd and Cu, and this can slow the catalytic reaction. To further pinpoint the active species, PdCl2/Cu-Cu2O catalysts with different Cu2O contents were prepared by controlling the dosages of glucose. The maximum DEC yield obtained with these catalysts was 151.9 mg.g-1.h-1, corresponding to an ethanol conversion of 7.2% and 97.9% DEC selectivity on an ethanol basis. Therefore, it was concluded that Cu＋ was the active species in this catalytic system, possibly because a higher proportion of Cu＋ reduces the Pd2＋ concentration and limits the CO oxidation side reaction, thus increasing DEC selectivity. In addition, Cu＋ promotes electron transfer between Pd and Cu without an induction period, which could also promote the catalytic activity.
文摘In order to improve the yield and stability of ferrate in solution, dissolved Fe(Ⅵ) prepared with NaOH and KOH respectively was compared in this study. The results showed that KOH is more suitable than NaOH for the preparation of dissolved Fe(Ⅵ) at temperature over 50 ℃. It is found that the dissolved Fe(Ⅵ) prepared with KOH increases quickly at first, and then slowly with the increasing concentrations of OH-and ClO-, while it increases rapidly at first and then decreases rapidly with the increasing dosage of Fe(NO3)3·9H2O. These results are different from that prepared with NaOH. It can be explained that solid K2FeO4 salts can be formed in KOH solution, and it will lower the Fe(Ⅵ) concentration, counteract the decomposition of Fe(Ⅵ), and improve the yield of Fe(Ⅵ). The maximum ferrate concentration is 0.163 mol/L obtained by 100 g/L Fe(NO3)3·9H2O and 6.16 mol/L KOH at 65 ℃. The stability of Fe(VI) is greatly improved due to the hypochlorite existed in the dissolved ferrate, and only 24% Fe(Ⅵ) has been decomposed after 16 d for 1 mmol/L Fe(Ⅵ) at 25 ℃.
