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由于制备液体燃料的费托合成工艺在合成过程中排放的费托反应生成水通常含有水溶性含氧化合物,例如醇、醛、酮和羧酸.费托反应生成水酸性强、成分复杂、种类繁多,因此需处理后才能排放.本文以核磁共振(NMR)为主要技术手段,以正丁醇和丙酸作为费托反应生成水中水溶性有机成分的模型化合物,研究了腐殖酸(HA)对费托反应生成水的吸附作用.1H NMR滴定实验和1H弛豫时间测定结果显示:随HA浓度增大,正丁醇质子信号变宽,但化学位移未变;丙酸质子信号变宽,且化学位移向高场移动;正丁醇和丙酸的1H自旋-晶格和自旋-自旋弛豫时间均降低,分子相关时间增大.HA与正丁醇、丙酸的结合百分比表明HA对正丁醇的吸附作用大于丙酸.增加HA浓度有利于HA与正丁醇相互作用,但溶液pH值对HA(20 mg/mL)与正丁醇相互作用影响较小;另一方面,增加HA浓度、降低溶液pH值均有利于HA与丙酸相互作用,且HA浓度对相互作用的影响高于溶液pH值.本研究表明HA用于吸附处理费托反应生成水有效,且过程简单、价格低廉,在工业应用中具有潜力. 相似文献
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Impact of oxygen in electrical properties and hot-carrier stress-induced degradation of GaN high electron mobility transistors
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Lixiang Chen 《中国物理 B》2021,30(10):108502-108502
The role of the oxygen in AlGaN/GaN high electron mobility transistors (HEMTs) before and after semi-on state stress was discussed. Comparing with the electrical characteristics of the devices in vacuum, air, and oxygen atmosphere, it is revealed that the oxygen has significant influence on the electric characteristics and the hot-carrier-stress-induced degradation of the device. Comparing with the situation in vacuum, the gate leakage increased an order of magnitude in oxygen and air atmosphere. Double gate structure was used to separate the barrier leakage and surface leakage of AlGaN/GaN HEMT it is found that surface leakage is the major influencing factor in gate leakage of SiN-passivated devices before and after semi-on state stress. During semi-on state stress in the oxygen atmosphere, the electric-field-driven oxidation process promoted the oxidation of the nitride layer, and the oxidation layer in the SiN/AlGaN interface leads to the decreasing of the surface leakage. 相似文献
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本文研究了更新过程中的几个随机比较结果.通过对不同时刻之前的最后一次更新发生时刻变量在失效率序、反向失效率序和似然比序意义下的随机比较,获得了若底分布F是IFR,则t之前最后一次更新的发生时刻变量SN(t)在失效率序和反向失效率序意义下关于t单调递增;若底分布F是IFR且绝对连续,则SN(t)在似然比序意义下关于t单调递增. 相似文献
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