To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular me...To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular mechanism of the antioxidant reaction of hindered phenol,diphenylamine,and alkyl sulfide are studied via molecular simulations.Calculation results show that the strong electron-donating ability and high hydrogen-donating activity of the antioxidant molecule and the low hydrogen-abstracting activity of free radicals formed after dehydrogenation are the internal molecular causes of the shielding of phenol and diphenylamine from scavenging peroxy free radicals,and the strong electron-donating ability is the internal molecular cause of the high activity of thioether in decomposing alkyl hydrogen peroxide.Based on this antioxidant molecular mechanism,a molecular design rule of antioxidant is proposed,namely“high EHOMO,large Q(S),low bond dissociation energy BDE(O—H)and BDE(N—H)”.Two new antioxidants,PAS-I and PAS-II,are designed and prepared by chemical bonding of hindered phenol,diphenylamine,and sulfur atoms.Experimental results show that these antioxidants both have excellent antioxidant effects in lubricating oil,and that PAS-II is the superior antioxidant,consistent with theoretical predictions.展开更多
The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show ...The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show that(BF_(3))_(2)·n-C_(4)H_(9)OH catalyzes the 1-decene oligomerization reaction with higher activity compared to BF_(3)·n-C_(4)H_(9)OH,which is the most catalytically active substance in the BF_(3)/n-C_(4)H_(9)OH catalyst system.The reaction energy barriers and heats of reaction of chain initiation,chain growth,and chain termination in BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization are calculated to reveal the product distribution.The calculation results show that the contents of the oligomerization reaction products in descending order are trimer,tetramer,pentamer,and dimer.The calculated results were consistent with the experimentally obtained product distribution.展开更多
电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄...电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄像机拍摄实验图像.引入电场强度、气泡体积与溶液介电常数作为变量,探究其对于气泡动力学特性的影响.观测了竖直与水平均匀电场中气泡的上升过程,分析了不同变量下气泡变形状况与上升速度的变化.引入气泡长宽比L/D用于表示气泡拉伸变形程度,截取单个气泡上升过程分时段图像展示形态变化过程.研究结果表明,气泡沿电场方向伸长,且电场强度越大,变形越明显;竖直电场中气泡伸长导致上升速度增大,而水平电场中气泡上升速度减小.气泡尺寸增大,浮升力作用增强,气泡上升速度增大.溶液介电常数增加,电场力作用明显增加,气泡变形更加明显.展开更多
文摘To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular mechanism of the antioxidant reaction of hindered phenol,diphenylamine,and alkyl sulfide are studied via molecular simulations.Calculation results show that the strong electron-donating ability and high hydrogen-donating activity of the antioxidant molecule and the low hydrogen-abstracting activity of free radicals formed after dehydrogenation are the internal molecular causes of the shielding of phenol and diphenylamine from scavenging peroxy free radicals,and the strong electron-donating ability is the internal molecular cause of the high activity of thioether in decomposing alkyl hydrogen peroxide.Based on this antioxidant molecular mechanism,a molecular design rule of antioxidant is proposed,namely“high EHOMO,large Q(S),low bond dissociation energy BDE(O—H)and BDE(N—H)”.Two new antioxidants,PAS-I and PAS-II,are designed and prepared by chemical bonding of hindered phenol,diphenylamine,and sulfur atoms.Experimental results show that these antioxidants both have excellent antioxidant effects in lubricating oil,and that PAS-II is the superior antioxidant,consistent with theoretical predictions.
基金This work was financially supported by China Petrochemical Corporation Project(120055).
文摘The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show that(BF_(3))_(2)·n-C_(4)H_(9)OH catalyzes the 1-decene oligomerization reaction with higher activity compared to BF_(3)·n-C_(4)H_(9)OH,which is the most catalytically active substance in the BF_(3)/n-C_(4)H_(9)OH catalyst system.The reaction energy barriers and heats of reaction of chain initiation,chain growth,and chain termination in BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization are calculated to reveal the product distribution.The calculation results show that the contents of the oligomerization reaction products in descending order are trimer,tetramer,pentamer,and dimer.The calculated results were consistent with the experimentally obtained product distribution.
文摘电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄像机拍摄实验图像.引入电场强度、气泡体积与溶液介电常数作为变量,探究其对于气泡动力学特性的影响.观测了竖直与水平均匀电场中气泡的上升过程,分析了不同变量下气泡变形状况与上升速度的变化.引入气泡长宽比L/D用于表示气泡拉伸变形程度,截取单个气泡上升过程分时段图像展示形态变化过程.研究结果表明,气泡沿电场方向伸长,且电场强度越大,变形越明显;竖直电场中气泡伸长导致上升速度增大,而水平电场中气泡上升速度减小.气泡尺寸增大,浮升力作用增强,气泡上升速度增大.溶液介电常数增加,电场力作用明显增加,气泡变形更加明显.
