Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electro...Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electrocatalytic oxidations of saturated alcohols(C_(1)-C_(6))to selectively form formate using Ni Co hydroxide(Ni Co-OH)derived Ni Co_(2)O_(4)solid-acid electrocatalysts with balanced Lewis acid(LASs)and Brønsted acid sites(BASs).Thermal treatment transforms BASs-rich(89.6%)Ni Co-OH into Ni Co_(2)O_(4)with nearly equal distribution of LASs(53.1%)and BASs(46.9%)which synergistically promote adsorption and activation of OH-and alcohol molecules for enhanced oxidation activity.In contrast,BASs-enriched Ni Co-OH facilitates formation of higher valence metal sites,beneficial for water oxidation.The combined experimental studies and theoretical calculation imply the oxidation ability of C1-C6alcohols increases as increased number of hydroxyl groups and decreased HOMO-LUMO gaps:methanol(C_(1))<ethylene glycol(C_(2))<glycerol(C3)<meso-erythritol(C4)<xylitol(C5)<sorbitol(C6),while the formate selectivity shows the opposite trend from 100 to 80%.This study unveils synergistic roles of LASs and BASs,as well as hydroxyl group effect in electro-upgrading of alcohols using solid-acid electrocatalysts.展开更多
采用热力学和动力学方法研究了轴承钢GCr15凝固过程中溶质元素偏析、钛夹杂析出规律及影响钛夹杂长大的因素。研究表明:1)GCr15钢在凝固过程中Ti(C_(x)N_(1-x))先于TiN在凝固前沿的固液两相区析出,降低钢液初始Ti、N含量均能推迟Ti(C_(x...采用热力学和动力学方法研究了轴承钢GCr15凝固过程中溶质元素偏析、钛夹杂析出规律及影响钛夹杂长大的因素。研究表明:1)GCr15钢在凝固过程中Ti(C_(x)N_(1-x))先于TiN在凝固前沿的固液两相区析出,降低钢液初始Ti、N含量均能推迟Ti(C_(x)N_(1-x))在凝固前沿的析出。Ti(C_(x)N_(1-x))夹杂中的x值随w(Ti)_(0)下降而下降,但随w(N)_(0)下降而升高。2)凝固冷却速率对GCr15钢中Ti、N元素的凝固偏析影响不大,但对钛夹杂的长大影响显著。随着钢液初始Ti、N含量下降,钛夹杂凝固析出推迟,尺寸变小。采用70 t EAF→EBT→LF→RH→IC(模铸)工艺生产轴承钢GCr15大钢锭,从30 t GCr15钢锭经热锻/轧成的Ф75 mm圆棒上取样,w(T.O)、w(Ti)和w(N)分别为0.0007%、0.0010%、0.0019%。光学显微镜下检测到的钛夹杂是呈土红色的碳氮化钛夹杂;扫描电镜下观察到钢中钛夹杂形状不规则,钛夹杂最大尺寸17.4μm,平均尺寸为9.2μm,这与大吨位模铸锭冷却速率小有关。对大钢锭模铸而言,严格控制各工序钢水增Ti量和增N量,降低钢液中Ti、N含量,推迟钛夹杂在凝固过程中的析出是控制盾构机主轴承圆柱滚子用轴承钢GCr15产品钛夹杂尺寸的有效措施。展开更多
基金the financial support from the National Natural Science Foundation of China(52172110,52472231,52311530113)Shanghai"Science and Technology Innovation Action Plan"intergovernmental international science and technology cooperation project(23520710600)+1 种基金Science and Technology Commission of Shanghai Municipality(22DZ1205600)the Central Guidance on Science and Technology Development Fund of Zhejiang Province(2024ZY01011)。
文摘Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electrocatalytic oxidations of saturated alcohols(C_(1)-C_(6))to selectively form formate using Ni Co hydroxide(Ni Co-OH)derived Ni Co_(2)O_(4)solid-acid electrocatalysts with balanced Lewis acid(LASs)and Brønsted acid sites(BASs).Thermal treatment transforms BASs-rich(89.6%)Ni Co-OH into Ni Co_(2)O_(4)with nearly equal distribution of LASs(53.1%)and BASs(46.9%)which synergistically promote adsorption and activation of OH-and alcohol molecules for enhanced oxidation activity.In contrast,BASs-enriched Ni Co-OH facilitates formation of higher valence metal sites,beneficial for water oxidation.The combined experimental studies and theoretical calculation imply the oxidation ability of C1-C6alcohols increases as increased number of hydroxyl groups and decreased HOMO-LUMO gaps:methanol(C_(1))<ethylene glycol(C_(2))<glycerol(C3)<meso-erythritol(C4)<xylitol(C5)<sorbitol(C6),while the formate selectivity shows the opposite trend from 100 to 80%.This study unveils synergistic roles of LASs and BASs,as well as hydroxyl group effect in electro-upgrading of alcohols using solid-acid electrocatalysts.
文摘采用热力学和动力学方法研究了轴承钢GCr15凝固过程中溶质元素偏析、钛夹杂析出规律及影响钛夹杂长大的因素。研究表明:1)GCr15钢在凝固过程中Ti(C_(x)N_(1-x))先于TiN在凝固前沿的固液两相区析出,降低钢液初始Ti、N含量均能推迟Ti(C_(x)N_(1-x))在凝固前沿的析出。Ti(C_(x)N_(1-x))夹杂中的x值随w(Ti)_(0)下降而下降,但随w(N)_(0)下降而升高。2)凝固冷却速率对GCr15钢中Ti、N元素的凝固偏析影响不大,但对钛夹杂的长大影响显著。随着钢液初始Ti、N含量下降,钛夹杂凝固析出推迟,尺寸变小。采用70 t EAF→EBT→LF→RH→IC(模铸)工艺生产轴承钢GCr15大钢锭,从30 t GCr15钢锭经热锻/轧成的Ф75 mm圆棒上取样,w(T.O)、w(Ti)和w(N)分别为0.0007%、0.0010%、0.0019%。光学显微镜下检测到的钛夹杂是呈土红色的碳氮化钛夹杂;扫描电镜下观察到钢中钛夹杂形状不规则,钛夹杂最大尺寸17.4μm,平均尺寸为9.2μm,这与大吨位模铸锭冷却速率小有关。对大钢锭模铸而言,严格控制各工序钢水增Ti量和增N量,降低钢液中Ti、N含量,推迟钛夹杂在凝固过程中的析出是控制盾构机主轴承圆柱滚子用轴承钢GCr15产品钛夹杂尺寸的有效措施。
