为了解决釜式反应器制备双酚A环氧丙烯酸树脂(EA)过程中存在温度控制难、反应周期长和稳定性差等问题,采用具有高效传热和传质能力的微结构反应器来合成EA。研究了反应温度、流速、停留时间、催化剂种类及用量、管径对反应的影响,优化...为了解决釜式反应器制备双酚A环氧丙烯酸树脂(EA)过程中存在温度控制难、反应周期长和稳定性差等问题,采用具有高效传热和传质能力的微结构反应器来合成EA。研究了反应温度、流速、停留时间、催化剂种类及用量、管径对反应的影响,优化出最佳制备工艺。采用傅里叶红外光谱(FT-IR)对产物EA结构进行了表征。结果表明:应用微结构反应器可以成功制备EA。最佳制备条件如下:反应温度140℃,流速3.05 m L/min,停留时间4 min,管径1 mm,催化剂选用三苯基膦且用量为双酚A环氧树脂(EP)质量的2%。在最佳制备条件下,丙烯酸和环氧基的转化率分别为99.1%和96.3%。固化涂膜的附着力、铅笔硬度和耐磨性等,均达到了使用要求。展开更多
The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an ap...The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).展开更多
OX_(2)(X=halogen)molecules was studied theoretically.Calculation results show that delocalizedπ_(3)^(6) bonds exist in their electronic structures and O atoms adopt the sp^(2) type of hybridization,which violates the...OX_(2)(X=halogen)molecules was studied theoretically.Calculation results show that delocalizedπ_(3)^(6) bonds exist in their electronic structures and O atoms adopt the sp^(2) type of hybridization,which violates the prediction of the valence shell electron pair repulsion theory of sp^(3) type.Delocalization stabilization energy is proposed to measure the contribution of delocalizedπ_(3)^(6) bond to energy decrease and proves to bring extra-stability to the molecule.These phenomena can be summarized as a kind of coordinating effect.展开更多
文摘为了解决釜式反应器制备双酚A环氧丙烯酸树脂(EA)过程中存在温度控制难、反应周期长和稳定性差等问题,采用具有高效传热和传质能力的微结构反应器来合成EA。研究了反应温度、流速、停留时间、催化剂种类及用量、管径对反应的影响,优化出最佳制备工艺。采用傅里叶红外光谱(FT-IR)对产物EA结构进行了表征。结果表明:应用微结构反应器可以成功制备EA。最佳制备条件如下:反应温度140℃,流速3.05 m L/min,停留时间4 min,管径1 mm,催化剂选用三苯基膦且用量为双酚A环氧树脂(EP)质量的2%。在最佳制备条件下,丙烯酸和环氧基的转化率分别为99.1%和96.3%。固化涂膜的附着力、铅笔硬度和耐磨性等,均达到了使用要求。
文摘The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).
基金supported by the Provincial Innovation and Entrepreneurship Training Program of Jiangsu Province(No.201910319079Y)。
文摘OX_(2)(X=halogen)molecules was studied theoretically.Calculation results show that delocalizedπ_(3)^(6) bonds exist in their electronic structures and O atoms adopt the sp^(2) type of hybridization,which violates the prediction of the valence shell electron pair repulsion theory of sp^(3) type.Delocalization stabilization energy is proposed to measure the contribution of delocalizedπ_(3)^(6) bond to energy decrease and proves to bring extra-stability to the molecule.These phenomena can be summarized as a kind of coordinating effect.
