Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and a...Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and atmospheric pressure. The adsorbents were characterized by XRD, XRF and pyridine infrared spectrum （IR）. The adsorption experiments show that the desulfurization performance of Ce（IV）Y is much better than that of NaY. The sulfur removal over both NaY and Ce（IV）Y decreases with the increase of toluene concentration in MG, however, the decline tendency on Ce（IV）Y is smooth, and it is steep on NaY. FT-IR spectra of thiophene adsorption indicate that thiophene molecules are mainly adsorbed on NaY via π electron interaction, but on Ce（IV）Y, in addition to the π electron interaction, both Ce^4＋-S direct interaction and protonation of thiophene also play important roles. Toluene molecules are adsorbed on NaY also via π electron interaction. Although the amount of Bronsted acid sites is increased due to the introduction of Ce^4＋ ions into NaY zeolite, it is not found to influence the adsorption mode of toluene over Ce（IV）Y. Compared with NaY zeolite, the improved desulfurization performance over Ce（IV）Y for removing organic sulfur compounds from MG solution, especially those containing large amount of aromatics, may be ascribed to the direct Ce（IV）-S interaction, which is much resistant to the influence resulted from toluene adsorption.展开更多
研究不同生长期马齿苋茎叶提取物的抗氧化活性。分别用70%乙醇和水浸提不同生长期马齿苋茎、叶部分,用分光光度法测定其醇提物和水提物中多糖和总黄酮的含量,进行体外抗氧化活性实验。盛花期马齿苋茎中的多糖和黄酮含量最高,但水提物高...研究不同生长期马齿苋茎叶提取物的抗氧化活性。分别用70%乙醇和水浸提不同生长期马齿苋茎、叶部分,用分光光度法测定其醇提物和水提物中多糖和总黄酮的含量,进行体外抗氧化活性实验。盛花期马齿苋茎中的多糖和黄酮含量最高,但水提物高于醇提物。不论是水提物还是醇提物,不同生长期马齿苋茎中的多糖含量高于叶,而叶中的黄酮含量高于茎。在实验浓度范围内,两种溶剂提取物均有良好的抗氧化活性,随着提取物浓度的增加对羟基自由基（·OH）的清除能力增强,而对Ce（Ⅳ）的还原能力并不都是随浓度的增加而增强。在添加量为0.10~0.60 m L时,水提物对·OH的清除能力强于Vc,各个生长期马齿苋茎、叶水提物的抗氧化力强于醇提物,同一生长期茎对·OH的清除率都大于叶。添加量为0.50 m L时,水提物对Ce（Ⅳ）还原率最大的是花蕾期茎和盛花期叶达到79.64%。添加量为0.80 m L时,水提物对·OH的清除率最大的是花蕾期茎高达82.81%,醇提物对·OH的清除率最大的也是花蕾期茎为75.86%。展开更多
基金supported by the Fundamental Research Funds for the Key Universities (Grant No. DUT10LK25)the National Natural Science Foundation of China (Grant No. 21106014)
文摘Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and atmospheric pressure. The adsorbents were characterized by XRD, XRF and pyridine infrared spectrum （IR）. The adsorption experiments show that the desulfurization performance of Ce（IV）Y is much better than that of NaY. The sulfur removal over both NaY and Ce（IV）Y decreases with the increase of toluene concentration in MG, however, the decline tendency on Ce（IV）Y is smooth, and it is steep on NaY. FT-IR spectra of thiophene adsorption indicate that thiophene molecules are mainly adsorbed on NaY via π electron interaction, but on Ce（IV）Y, in addition to the π electron interaction, both Ce^4＋-S direct interaction and protonation of thiophene also play important roles. Toluene molecules are adsorbed on NaY also via π electron interaction. Although the amount of Bronsted acid sites is increased due to the introduction of Ce^4＋ ions into NaY zeolite, it is not found to influence the adsorption mode of toluene over Ce（IV）Y. Compared with NaY zeolite, the improved desulfurization performance over Ce（IV）Y for removing organic sulfur compounds from MG solution, especially those containing large amount of aromatics, may be ascribed to the direct Ce（IV）-S interaction, which is much resistant to the influence resulted from toluene adsorption.
文摘A mild and reliable procedure for the preparation of alpha-arylpropanoic acids from arylpropanone by Ce(IV) salt oxidative rearrangement is discribed.
文摘研究不同生长期马齿苋茎叶提取物的抗氧化活性。分别用70%乙醇和水浸提不同生长期马齿苋茎、叶部分,用分光光度法测定其醇提物和水提物中多糖和总黄酮的含量,进行体外抗氧化活性实验。盛花期马齿苋茎中的多糖和黄酮含量最高,但水提物高于醇提物。不论是水提物还是醇提物,不同生长期马齿苋茎中的多糖含量高于叶,而叶中的黄酮含量高于茎。在实验浓度范围内,两种溶剂提取物均有良好的抗氧化活性,随着提取物浓度的增加对羟基自由基（·OH）的清除能力增强,而对Ce（Ⅳ）的还原能力并不都是随浓度的增加而增强。在添加量为0.10~0.60 m L时,水提物对·OH的清除能力强于Vc,各个生长期马齿苋茎、叶水提物的抗氧化力强于醇提物,同一生长期茎对·OH的清除率都大于叶。添加量为0.50 m L时,水提物对Ce（Ⅳ）还原率最大的是花蕾期茎和盛花期叶达到79.64%。添加量为0.80 m L时,水提物对·OH的清除率最大的是花蕾期茎高达82.81%,醇提物对·OH的清除率最大的也是花蕾期茎为75.86%。
