镓锗铜萃余液综合利用研究与应用

本文针对镓锗铜综合回收系统产出的萃余液,设计通过中和氧化除杂、锌粉置换除铜镉、有机试剂除钴镍、纯碱法生产碱式碳酸锌、高温煅烧生产活性氧化锌和一步法生产元明粉的生产工艺流程,有效的将镓锗铜萃余液分类分离富集,产出具有价值的富集渣和工业产品,进一步提升综合回收经济效益。     

OMS-2催化剂成型工艺研究及其在印染废水处理中的应用

以OMS-2粉体催化剂为基础,对催化剂进行挤出成型,考察粘结剂种类、粘结剂用量、润滑剂和孔结构改进剂用量、焙烧温度对成型催化剂机械强度的影响。得到最佳成型工艺条件为,粘结剂硅溶胶用量为OMS-2粉体催化剂质量的105%～110%、辅助粘结剂纳米ZrO_2用量为OMS-2粉体催化剂质量的30%～35%、润滑剂田菁粉用量为OMS-2粉体催化剂质量的2. 5%～3. 0%、孔结构改进剂柠檬酸用量为OMS-2粉体催化剂质量的5%～6%,焙烧温度450℃。成型后催化剂机械强度可达150 N·cm~(-1),满足工业化应用对催化剂强度的要求。将成型催化剂应用于催化湿式氧化印染废水处理,经过432 h活性评价时间,COD平均去除率约91. 6%,反应结束后催化剂结构完整,平均机械强度约144 N·cm~(-1),表现出良好的水热稳定性。     

光伏废料制备Si3N4-SiC材料的抗氧化性和抗侵蚀性

将光伏废料经酸洗除杂后,与硅粉按85∶15的质量比配料,以聚乙二醇做结合剂,成型为10 mm×10 mm×20 mm的生坯后,在1380℃保温2 h氮化制成Si3N4-SiC材料,然后研究了该Si3N4-SiC材料的抗氧化性和抗侵蚀性。结果表明:1)制备的Si3N4-SiC材料在空气气氛中抗氧化性较好,主要是由于其氧化产物Si2N2O和SiO2填充气孔,促进烧结,提高了试样的致密度。2)在静态熔盐(Na3AlF6)中的抗侵蚀性能较好,主要是由于Na3AlF6渗入气孔中,使其显气孔率降低。3)在动态熔盐中的抗侵蚀性相对变差,主要是由于CO2气体的搅拌和对Si3N4、SiC的氧化二者共同作用的结果。     

Phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts for efficient hydrazine oxidation reaction

In this study, a series of phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts has been obtained for efficient hydrazine oxidation reaction (HzOR). These (Ni@Pt–P/C) electrocatalysts were prepared by a primary replacement method followed by subsequent phosphating process. Among all Ni@Pt–P/C electrocatalysts, as-prepared Ni@Pt–P/C-400 electrocatalyst shows the highest HzOR performance (515 mA mg⁻¹_Pt), best stability, durability and lowest activation energy (12.60 kJ mol⁻¹). The satisfactory HzOR performance is mainly resulted from the unique design of phosphating effect on core-shell structure which producing good synergistic effect between Ni, P and Pt. This work would pave a way for developing other low-Pt catalysts in the future.     

Contribution of the Internal and External Oxygen to the Oxidation of Microencapsulated Fish Oil

Microencapsulation aims to protect polyunsaturated fatty acids against oxidation by embedding oil droplets in a solid matrix. In such a system the internal (dissolved and entrapped) and external (in the environment) oxygen can be differentiated. The study aims to quantify the impact of both oxygen sources on the oxidation of microencapsulated fish oil. The impact of the solubilized oxygen in bulk fish oil is investigated by saturating the oil with nitrogen, synthetic air, and pure oxygen. Even though more dissolved oxygen results in more oxidation products, the difference between the oxidation of the nitrogen and air saturated oil is significant but low. For encapsulated fish oil powders, the internal oxygen is modified by preparing oil‐in‐water emulsions under atmospheric and inert conditions. The feed is atomized and spray dried with either nitrogen or air. Powders are stored under vacuum and in vials and the hydroperoxides and anisidine value are determined in the total‐ and encapsulated oil. The internal oxygen has a minor impact, whereas the external oxygen is the main determinant for autoxidation. Apart from oxidizing the non‐encapsulated oil, the external O₂ penetrates into the particle and reacts with the encapsulated oil. Practical Applications: Comparing the contribution of the internal and external oxygen to the oxidative stability shows that the internal O₂ plays a minor role and can be neglected. This means that the emulsion preparation as well as the spray drying process can be conducted under ambient conditions. An inert production is not extending the shelf life significantly as long as the external O₂ determines oxidation. The focus should be on optimizing the diffusion barrier properties of the wall matrix to reduce the penetration of the external oxygen into the particle system. Alternatively, packaging solution reducing the external O₂ will extend the shelf life of the microencapsulated oil.     

Investigation of flame spray synthesized La1-xSrxCoO3 perovskites with promotional catalytic performances on CO oxidation

To enhance the activity of catalysts for CO removal, the perovskite-type catalysts La_1-xSr_xCoO₃ (x = 0, 0.2, 0.4, 0.6, and 0.8) with different Sr²⁺ doping amount were synthesized by flame spray synthesis (FSS) method. The perovskite-type catalyst synthesized by FSS has a much larger specific surface area (SSA) than that prepared by other conventional methods. The SSA of catalyst increases with the increase of Sr²⁺ doping amount and the SSA of La_0.2Sr_0.8CoO₃ reaches 31.65 m²/g. Compared with other conventional methods, FSS method significantly improves the activity of catalyst and makes it close to the performances of catalysts with surface modification. The substitution of La³⁺ by Sr²⁺ promotes the generation of secondary phase Co₃O₄ and SrCO₃. The catalytic activity of La_1-xSr_xCoO₃ increases with the addition of Sr²⁺, which results from the increasing active sites and oxygen vacancies. Interestingly, La_0.4Sr_0.6CoO₃ performs the highest activity for CO oxidation and the CO conversion reaches 50% at 148.6 °C and 90% at 165.9 °C. The oxidation of CO over La_1-xSr_xCoO₃ catalyst may follow a combination of MvK and L-H mechanisms according to the experimental results of H₂-TPR. Moreover, the catalyst exhibits good catalytic activity in consecutive oxidation cycles. In consecutive oxidation experiments with La_0.4Sr_0.6CoO₃, the CO conversion reaches 50% at 168.8 °C and 90% at 197.8 °C in the eighth oxidation cycle. These results prove that FSS method can further improve the activity of catalysts and is suitable for the preparation of efficient catalysts.     

红阳二矿12号煤层标志性气体实验研究

针对红阳二矿12号煤层遗煤氧化的规律与特点，有效地进行防灭火工作，掌握采空区中遗煤氧化的速度，对红阳二矿12号煤层进行了煤样升温氧化实验，在温度不断升高的过程中检测出CO与多种烯烃气体，并且在不同温度下煤体析出气体的速度不同，最终选择CO、C₂H₄、C₂H₂作为标志性气体，产生的临界温度分别为59、176、403 ℃。在采空区检测出CO气体，说明采空区遗煤进入快速氧化阶段；检测出C₂H₄气体时，遗煤进入剧烈氧化状态；检测出C₂H₂气体时，说明采空区中已经产生明火，井下人员需要迅速撤离。通过煤体标志性气体的确定，建立12号煤层自燃预警系统，保证井下工作人员的生命安全与能源的充分利用。     

微弧氧化Mg-3Al-1Zn镁合金应力腐蚀和腐蚀疲劳行为研究

本文主要对微弧氧化Mg-3Al-1Zn镁合金在空气和3.5 wt.%硫酸钠溶液两种环境下的应力腐蚀和腐蚀疲劳行为进行研究，并讨论其相互关系。微弧氧化处理后，Mg-3Al-1Zn镁合金的耐蚀性能得到明显改善。与Mg-3Al-1Zn镁合金基体相比，在空气中，微弧氧化后合金的应力腐蚀和腐蚀疲劳强度均下降了大约10 MPa。在3.5 wt.%硫酸钠溶液环境中，微弧氧化后合金的腐蚀疲劳性能仍然是恶化的，但是应力腐蚀强度却得到了显著改善，从58.24 MPa提高至202.08 MPa。这表明材料的力学性能（应力腐蚀和腐蚀疲劳）并不是与其腐蚀性能完全保持线性关系的。微弧氧化处理后镁合金在空气中的应力腐蚀断口为韧性断裂，在硫酸钠溶液环境中为解理断裂。而其腐蚀疲劳断口不论是在空气中还是在腐蚀环境中均为解理断裂。这主要是由于腐蚀环境和变换循环载荷的影响，两者共同作用将会加速裂纹扩展。这表明，周围环境和加载类型对材料断裂机理有重要影响。     

Anodic process on Cu−Al alloy in KF−AlF3−Al2O3 melts and suspensions

Anodic processes on Cu−10Al electrode in molten KF−AlF₃−Al₂O₃ (saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio (CR= x(KF)/x(AlF₃)), temperature and particle volume fraction (ϕ) on the electrochemical behaviour of the anode were demonstrated. Initially, the anode was polarised in the galvanostatic mode in melt and suspensions (ϕ=0.12, 0.15) at 750 °C with 0.4 A/cm² current density. The anode potential in melt varied between 2.5 and 3.2 V and in suspensions (ϕ= 0.12) between 3.3 and 3.4 V. XRD analysis was conducted to study the oxide phases on the anode surface. Anode limiting current densities and mass transfer coefficients drastically decreased with the increase of ϕ in the suspension. The results suggest that the Cu−10Al electrode works better in suspensions with CR of 1.4 and particle volume fraction of 0.09 at 800 °C.     

High-performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

With an increase in awareness about the need for green chemistry, there is a shift in focus towards identifying eco-compatible technologies that can improve product yield and eliminate the use or generation of hazardous compounds. An immediate practical example of such an approach is the development of sustainable methods for alcohol oxidation as alternatives to the current processes that are energy intensive and rely on ecotoxic chemicals. In this regard, heterogeneous photocatalysis has been identified as a robust technique to catalyze reactions under benign conditions, which would otherwise require harsh synthesis routes. With the advent of materials sciences and nanotechnology, there has been a tremendous increase in the scope of applicability of photocatalysis in fine chemicals synthesis. Though an attractive choice, much of the fundamental information pertaining to catalyst activity, selectivity and reaction conditions for optimum conversion are still to be investigated for most of these systems. To this end, this review will encompass recent achievements in the selective photocatalytic oxidation of alcohols by harnessing solar radiation as a viable source of energy. The discussion will be arranged based on common types of photocatalysts reported in literature, namely metal oxides (eg, TiO₂ and ZnO, Nb₂O₅), sulphides (eg, CdS, CuS, and Bi₂S₃), and carbonaceous photocatalysts (eg, g-C₃N₄). Several such candidates for photocatalysts will be discussed critically with the aim of providing useful insight into developing selective photocatalysts that can oxidize alcohols via eco-friendly pathways along with high yields.