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电沉积NiHCF薄膜在碱土金属溶液中的电控离子分离性能 总被引:4,自引:0,他引:4
采用电沉积方法在铂基体上制备出电活性NiHCF(Nickel Hexacyanoferrate)薄膜,在碱土金属溶液中考察了薄膜电极对碱土金属离子的电控离子分离性能.通过循环伏安法在0.1mol·L-1Mg(NO3)2、Ca(NO3)2、Sr(NO3)2和Ba(NO3)2溶液中可逆置入和释放碱土金属离子,比较了不同溶液中NiHCF膜电极的电活性、电化学行为和离子的置入机制;在0.1mol·L-1[Mg(NO3)z Ba(NO3)2]混合溶液中结合电化学石英晶体微天平(EQCM)原位检测了不同浓度下膜电极氧化还原过程中的伏安特性曲线和频率响应,分析了薄膜对Mg/Ba离子的选择性;并通过XPS测定了氧化还原状态下NiHCF膜的化学组成及元素价态.结果表明,NiHCF膜在二价碱土金属溶液中具有可逆的离子交换行为,对Ba2 离子的选择性大于Mg2 离子,通过电控离子分离方法可以实现碱土金属离子的有效分离. 相似文献
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液-固流化床中液速分布与颗粒循环流动 总被引:4,自引:0,他引:4
通过理论分析和实验研究考察了液一固平板流化床中颗粒流和液流的运动规律,提出了将分散的颗粒流连续介质化的假设和基于容积通量的流休力学表达方式,建立了液体流动和颗粒循环流动的数学模型并定义了颗粒流与液流的有效粘度。理论计算表明,液体通量的径向分布为抛物线,液流有效粘度和液含率与表观液速有关:颗粒通量的径向分布也为抛物线且颗粒上流区与回流区的分界点在0.577D,循环流动强度取决于液含率和液体密度,但颗粒循环分界点的位置与颗粒类型和操作液速无关。实验观察支持模型预测结果。 相似文献
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Polarization data of BH-4 oxidation on Cu anode in alkaline solution were measured at steady state by a self-made experimental cell. The experimental polarization curve showed three regions:the region at lower over-potential η(below 0.4 V approximately),the region at higher η(above 0.6 V approximately)and the transitional region at medium η. It was found that the limiting current density is caused by the limiting elemental step rather than the external mass transport. The apparent reaction order with respect to BH-4 changes from 0 to 1. The active energy is about 40 kJ·mol-1 in both regions with lower and higher η,and is higher than 40 kJ·mol-1 in the transitional region. With the experimental temperatures and NaOH concentration,the hydrogen production rates released by the electrode reaction were measured at [BH-4]/[OH-]ratios of 1∶40,1∶20,1∶6. 7 and 1∶4,which is strongly dependent on the over-potential. The apparent number of released electron n by the reaction was calculated by using the measured amounts of hydrogen and coulomb. Higher value of n was obtained at lower [BH-4]/[OH-]ratio,higher temperature as well as higher over-potential. Under the experimental conditions,the value of n varies from 0 to 7,while in the transitional region it is just in the range of 3 to 5. The experimental results indicate that the limiting current density or n value will increase by virtue of proper experimental conditions. However,to considerably increase the current density at lower over-potential requires a modified anode with higher activity. 相似文献
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Two types of Sb-doped SnO2 films on titanium substrate were prepared by the combination of electro-deposition and dip-coating (Ti/SnO2-Sb2O4/SnO2-Sb2O4) and single dip-coating (Ti/SnO2-Sb2O4), respectively. The surface morphology and crystalline structure of both film electrodes were characterized using X-ray diffractometry(XRD) and scanning electron microscopy(SEM). XRD spectra indicate that the rutile SnO2 forms in two films and a TiO2 crystallite exists only in Ti/SnO2-Sb2O4 electrode. SEM images show that the surface morphology of two films is typically cracked-mud structure. The photooxidation experiment was proceeded to further confirm the two electrode activity. The results show that the photoelectrocatalytic degradation efficiency of Ti/SnO2-Sb2O4 electrode with sub-layer is higher than that of simple Ti/SnO2-Sb2O4 electrode using phenol as a model organic pollutant. The Ti/SnO2-Sb2O4/SnO2-Sb2O4 photoanode has a better photoelectrochemical performance than Ti/SnO2-Sb2O4 photoanode for the removal of organic pollutants from water. 相似文献
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本文简述了高温催化燃烧的原理, 概括了燃烧速率与温度的关系, 并详述了高温催化燃烧用催化剂的基体、载体和活性组分材料科研与开发近况, 指出筛选和制备出一种以氧化铝或氧化镁或其它耐高温、比表面大的氧化物为基体, 在其上引入高温下具较强活性组分的复合型氧化物涂层, 使其获得较大的比表面积及较佳的热稳定性, 并具有一定活性的催化剂是高温催化燃烧催化剂发展趋势。 相似文献
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ADM机械化求解反应工程数模中非线性常微分方程边值问题 总被引:6,自引:4,他引:2
对于反应工程中非线性常微分方程边值问题,本文应用MATHEMATICA软件实现了任意阶逼近解析的机械化,并给出了该类方程求解的普遍化程序。文中简明扼要地介绍了基于“参数化分解”的ADM(adomian decomposition method)机械化程序的原理、框图和求解过程。以多孔催化剂内扩散-反应耦联的非线性方程为例,给出了催化剂颗粒内浓度分布的逼近解析前八项表达式和效率因子η曲线,并将该逼近解析方法与有限差分法BAND(J)进行了对比,结果表明:ADM容易收敛,且计算结果与数值方法高度一致。文中还从应用的角度出发,分析了与设计和操作有关的参数,即反应级数n、Thiele模数φ和催化剂的几何形状α,在非线性情况下与催化剂效率因子η的函数关系,并着重讨论了这些参数取值变化对ADM求解过程的影响。本文不但为求解化工数模中的非线性常微分方程提供了新思路,也为化学工程师们提供了一个理论分析和计算的简便工具。 相似文献
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从一般工程理论的基本衡算概念出发,用累积项、散度和化学源(反应项)的概念解释了反应工程理论数模的普遍微分形式,并指出,反应系统中与化学动力学相关的物理量分布,即质量场和能量场,决定了表观的反应结果。作者认为,具有电化学源及传荷过程是电化学反应系统的特点,据此,经合理简化可导出多孔电极稳态操作的普遍化理论数模,其形式为量纲1的非线性二阶微分方程组的边值问题,以描述多孔电极内浓差极化、欧姆极化和活化极化耦联的非线性理论关系;所归纳出的4个量纲1参数s、μ、α和γ,可给出系统动力学和传递过程相似的依据。扼要介绍了非线性数模逼近解析的Adomian分解法,以及自编的符号运算自动执行程序PAMC(parameterized ADM mathematica code),并例举了柱状和环状多孔电极理论极化曲线的计算结果。总之,非线性和复杂性研究将成为反应工程理论深入探索的方向之一。 相似文献
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