几种脱砷吸收剂的比较研究

利用模拟烟气,在自行设计的小型鼓泡反应器内,对几种脱砷吸收剂的性能进行了比较实验研究.结果表明:H_2O_2、NaClO、NaClO_2、Ca(ClO)_2以及复合吸收剂A(M/H2O_2)、F(N/NaClO_2)等脱砷剂脱砷效果明显.其中,复合吸收剂A、F脱除效率基本都能达到100%.复合吸收剂A成本较低,具有很好的工业应用前景.     

阳极氧化铝模板高有序孔的形成机理综述

阳极氧化铝模板法是合成纳米阵列材料的最常用的方法,然而有关氧化铝纳米孔的形成机理却没有达到统一的认识.利用26篇文献综述了氧化铝膜的理想结构和电场辅助的溶解模型、体积膨胀的应力模型、稳态孔的生长模型、临界电流的密度模型和梅花结构模型等5种不同的氧化铝纳米孔形成机理,最后对氧化铝模板的应用和发展前景提出了展望.     

高钛球团焙烧行为及其强化技术

研究了高钛球团的焙烧特征和固结行为.随着TiO2含量的增加,球团焙烧难度增大,当TiO2质量分数由10%增加至21%时,高钛球团所需预热时间由12 min延长至26 min以上,焙烧球强度由每个2486 N降低至每个1728 N.高钛球团由于FeTiO3含量高,导致氧化速度慢、预热球氧化程度低,不利于焙烧固结时钛赤铁矿固溶体晶粒的长大,使得球团固结强度差.通过添加NaOH结合润磨工艺增大颗粒表面能和反应活性,促进了固相扩散,并生成少量低熔点化合物,有利于再结晶过程的扩散迁移,使Ti富集在Fe2 TiO5中并促进钛赤铁矿晶粒长大,强化了高钛球团焙烧固结,可使预热时间缩短至16 min,球团强度提高至每个2141 N.     

Effect of Mg substitution for La on microstructure, hydrogen storage and electrochemical properties of La1−xMgxNi3.5 (x=0.20, 0.23, 0.25 at%) alloys

The effect of Mg substitution for La on microstructure, hydrogen storage and electrochemical properties of the annealed La_(1-x) Mg_x Ni_3.5(x=0.20, 0.23, 0.25 at%) alloys have been studied. All the samples were mainly composed of(LaMg)_2Ni_7,(LaMg)Ni_3, and LaNi_5 phases. Mg substitution for La changed the phase abundance, but did not change the constitution of all phases, which is con fi rmed by the results of backscattered SEM images and EDS analysis. The P–C isotherms indicated that the La_(1-x) Mg_x Ni_3.5alloys reversibly absorbed and desorbed hydrogen smoothly at 298 K. The hydrogen absorption cyclic stabilities of La_(1-x) Mg_x Ni_3.5alloy after 5 hydrogen absorption/desorption cycles reached the maximum values of91.9% and 96.0% at 298 K and 323 K, respectively. The hydrogen desorption capacity and plateau pressure for the La_(1-x) Mg_x Ni_3.5alloy reached the maximum values of 1.055 H/M and 0.074 MPa, respectively. The desorption capacities of La_(1-x) Mg_x Ni_3.5reached 0.193 H/M and 0.565 H/M in the fi rst minute at 298 K and 323 K, respectively. Electrochemical property measurement indicated that La_(1-x) Mg_x Ni_3.5(x=0.20,0.23, 0.25 at%) alloys possessed excellent activation capability and were completely activated within3 cycles. Discharge capacities of La_(1-x) Mg_x Ni_3.5alloys reached 378.2 m A h/g(x = 0.20 at%), 342.7 m A h/g(x = 0.23 at%), and 369.6 m A h/g(x = 0.25 at%), respectively. Moreover, energy density of La_(1-x) Mg_x Ni_3.5alloy was much larger than that of La_0.80Mg_0.20Ni_3.5 alloy and nearly approaches the maximum value of La0.75Mg0.25Ni3.5. Thus, the La_(1-x) Mg_x Ni_3.5alloy exhibits optimum comprehensive properties of hydrogen storage and electrochemistry.     

NiO nanosheet assembles for supercapacitor electrode materials

In this paper, large scale hierarchically assembled Ni O nanosheets have been favorably fabricated through a facile hydrothermal route. The as-prepared Ni O nanosheet assembles were characterized in detail by various analytical techniques. The results showed these nanosheets present the thickness of about 30 nm and the surface area is 116.9 m~2 g~(-1). These NiO nanosheet assembles were used as the working electrode materials in electrochemical tests, which demonstrated a specific capacitance value of 81.67 Fg ~(-1)at the current density of 0.5 Ag~(-1)and excellent long cycle-life stability with 78.5% of its discharge specific capacitance retention after 3000 cycles at the current density of 0.5 Ag~(-1), revealing the as-synthesized NiO nanosheet assembles might be a promising electrode material for supercapacitor applications.     

Atomic layer deposition on Pd nanocrystals for forming Pd-TiO2 interface toward enhanced CO oxidation

Pd typically exhibits relatively low catalytic activity in CO oxidation, as CO is apt to be adsorbed on Pd to poison the surface for O2 activation. In this Letter, we report that this limitation can be overcome by integrating Pd with TiO2. The TiO2 was coated on Pd nanocubes with a controllable thickness using atomic layer deposition (ALD) method. Given the different work functions of TiO2 and Pd, the electrons in TiO2 semiconductor will flow toward Pd. With the electron density increased on Pd, the adsorption of CO to Pd will be weakened while the oxygen activation can be facilitated. Meanwhile, the interface-confined sites at Pd-TiO2 may further enhance the oxygen activation. As the species adsorption and activation are strongly correlated with electron density, the performance of Pd-TiO2 in CO oxidation turns out to depend on the TiO2 thickness, which determines the number of transferred electrons, within a certain range (<1.8 nm). This work provides a new strategy for enhancing catalytic performance through tailoring charge densities in hybrid catalysts.     

电催化氧化处理垃圾渗滤液

以复极性固定床电解槽为反应器,利用CuO-CeO₂/γ-Al₂O₃多相催化剂取代传统反应器的绝缘填料,构建电催化氧化体系。采用XRD、SEM对CuO-CeO₂/γ-Al₂O₃进行表征,考察了槽电压、pH、气体流量和极间距等因素对垃圾渗滤液降解的影响。结果表明,该体系对渗滤液具有较好的催化降解效果。当槽电压为15.0V、pH为中性、气体流量为0.08m³/h、极间距为3.0cm时,垃圾渗滤液COD和NH⁺₄-N的去除率分别达到93.7%和100%。在处理垃圾渗滤液的过程中,体系运行稳定,经过20次反复实验,降解效果仍能维持在70%以上。在电催化氧化体系的作用下,垃圾渗滤液中的难降解有机污染物被直接矿化或降解为小分子有机物;而NH⁺₄-N则主要被氧化为氮气和水。     

SNCR应用于水泥窑氮氧化物控制的氨氧化

为了对水泥窑应用SNCR控制技术时CaO催化NH3氧化问题进行研究,该文采用固定床反应器,研究温度(650～950℃)、NH3体积分数(100×10-6～1500×10-6)和O2体积分数(0～4%)对于CaO催化NH3氧化作用的影响。采用Fourier变换红外光谱仪(FTIR)测量NH3和NO组分的体积分数。实验结果表明:CaO催化NH3氧化反应的转化率和产物NO的选择性随NH3体积分数增加而下降,随温度和O2体积分数增加而增加。基于NH3转化率和产物NO选择性随NH3体积分数的变化规律,提出CaO催化NH3氧化的首要途径是NH3和O2的吸附,吸附态NH3会与O2反应生成NO,而非前人提出的NH3与CaO反应生成CaN。采用该机理可以较好地解释实验规律。     

Mn/MgO催化剂的表征及其对苯甲醇氧化的催化性能

以硝酸锰为前躯物,采用传统浸溃法合成了一系列不同锰含量的Mn/MgO催化剂.通过X射线衍射(XRD),N2物理吸附、Raman光谱、X射线吸收光谱(XAS)及程序升温还原(H2-TPR)对负载锰氧化物的分散度、氧化态、配位环境进行了表征.结果发现,Mn负载量是控制负载锰氧化物分散度和配位环境的重要因素.当Mn负载量小于...     

电解液中Ce(NO_3)_3/Ce_2(SO_4)_3的含量对Ti6Al4V合金微弧氧化膜层特性的影响

在硅酸钠-氢氧化钠电解液中以Na5P3O10作为稳定剂,通过改变Ce(NO3)3/Ce2(SO4)3的含量对Ti6Al4V合金进行微弧氧化,用XRD、SEM、EDS对试样表面所获得的氧化膜进行表征,并研究电解液中不同Ce(NO3)3/Ce2(SO4)3含量对氧化膜表面形貌的影响.结果表明,随着电解液中Ce3+的加入量增加到0.3 g/L,氧化膜表面的致密性减小,在此基础上加入0.5 g/L的Na5P3O10时,氧化膜致密性增加.EDS分析结果显示,膜层含有Ti、Na、Al、Si、P、O及Ce等元素;XRD分析结果表明,氧化膜的相组成为Ti、锐钛矿以及金红石.