从废钒催化剂中回收五氧化二钒

详细介绍了从废钒催化剂中回收Ｖ２Ｏ５的原理、工艺流程及适宜条件。     

钒渣提取五氧化二钒的研究

研究了从玉钢钒渣中提取五氧化二钒工艺。采用X荧光光谱分析和化学滴定法,系统地研究了添加剂用量、焙烧温度、沉钒温度和pH等因素对玉钢钒渣中五氧化二钒回收率的影响,并制定了合理的提钒流程参数。通过实验发现,在最佳流程参数条件下(添加剂与钒渣质量比为22:100,焙烧温度为850℃保温2h,沉钒时水浴温度为95℃,沉钒pH为2.2),五氧化二钒的回收率达到了85.4%,且五氧化二钒的纯度大于99%。     

分段溶解法从废钒催化剂中回收五氧化二钒

应用反浮选原理去除废钒催化剂中的大部分硅后，先在弱酸性介质中溶解出低价钒，然后对未溶物料进行高温焙烧，再在弱碱性介质中进行第二次溶解，使高价钒亦转入溶液中。浸出液轻氧化、中和处理，并用离子交换法净化料液，一次沉钒即可获得纯度达９９．５％的Ｖ２Ｏ５产品。钒回收率在９０％以上。     

从废钒催化剂中回收精制五氧化二钒的试验研究

简要介绍几种从废钒催化剂中回收五氧化二钒的工艺流程及特点。对两段逆流碱浸－重结晶－煅烧新工艺进行研究。结果表明,采用新工艺制得的五氧化二钒产品质量达到国家标准。该工艺流程简单,原材料消耗少,设备要求低。     

废钒触媒中回收五氧化二钒的新工艺

一、前言五氧化二钒用于制造钒铁合金、硫酸工业和有机合成工业中的催化剂、ADA法脱硫助催化剂、热钾碱脱碳缓蚀剂。近年来,在织物染色、瓷釉、半导体器件、超导材料和原子能等工业部门也得到广泛应用。     

蜂窝式脱硝催化剂中五氧化二钒的测定

采用磷钨钒酸分光光度法对蜂窝式SCR脱硝催化剂中五氧化二钒进行测定。试样经过氧化钠熔融分解后,热水提取,过滤除去氢氧化物沉淀。溶液用硫酸中和后,加入磷酸和钨酸钠,使钒形成黄色的磷钨钒酸配合物,使用紫外分光光度计进行测定,测定波长为420 nm。校准曲线方程为y=0.000 6x-0.000 5,线性相关系数为0.999 9,相对标准偏差为1.10%,平均回收率为99.3%。结果表明该方法简便可行,灵敏度较高,结果准确稳定,适用于蜂窝式脱硝催化剂中五氧化二钒的测定。     

钒触媒中五氧化二钒含量的测定方法

试样用酸分解,在硫酸介质中用高锰酸钾氧化,在尿素存在下,用亚硝酸钠分解过量的高锰酸钾,以N-苯基邻氨基苯甲酸为指示剂,用硫酸亚铁铵标准溶液滴定。本方法适用于低含量钒的测定。     

从废钒催化剂中回收五氧化二钒工艺研究

本试验采用沉淀法从接触法生产硫酸的废催化剂中回收V_2O_5。经还原酸浸、氧化水解沉钒、碱溶除杂,沉钒、焙烧等工序制得V_2O_5。总收率达90％,产品含量达99％以上。     

Phase equilibrium studies in V2O5-Fe2O3 and V2O5-TiO2 systems

V₂O₅-Fe₂O₃ and V₂O₅-TiO₂ systems represent two important chemical systems with various applications, including energy, catalysts, and high-performance materials. In the present study, high-temperature phase equilibrium experiments were conducted at the temperature range of 670–1000°C in air. Electron probe X-ray micro-analyzer (EPMA) was used to analyze the microstructure and composition of the phases presented in quenched samples. Systematic experiments demonstrated that V₂O₅-containing systems should not be quenched by water-based quenching media. Phase diagrams in both systems were constructed, and the eutectic and peritectic points of the systems were confirmed and compared with previous studies. The present study improved the previous results and could be used as the base for thermodynamic modelings and further applications of the two systems.     

V2O5负载量对V2O5／TiO2催化剂SCR法脱硝的影响

以TiO2载体,采用浸渍法制备了不同V2O5负载量的用于选择性催化还原NOx的V2O5／TiO2催化剂。利用BET,SEM和Ⅺ①,对不同V2O5负载量的催化剂组成、结构、形貌和性能进行了表征,考察不同V2O5负载量对催化剂制备的影响。结果表明制备的催化剂具有较多的中孔和微孔,催化剂中V2O5含量的增加,会降低催化剂的表面积;V2O5含量为2％的V2O5／TiO2催化剂样品比表面积最大,但是其活性非常低;V2O5含量为4％催化剂比表面积较大,NOx脱转化率高;V2O5的负载量小时,V2O5主要以等轴聚合的钒基型式（V3O7和V6O13）存在,这些钒基是催化剂的活性中心;当负载量超过6％,V2O5主要以结晶相存在,占据大量活性位,降低催化效果。     

A Critical Review of Technology for Selective Recovery of Vanadium from Leaching Solution in V2O5 Production

In the V₂O₅ production process, purification of vanadium-bearing solution plays an important role in determining the quality of the final product. The choice of purification method depends on the vanadium species, aqueous media, and associated impurities. In this review, the recent research results for the separation and recovery of vanadium from leaching solution with solvent extraction, ion exchange, and chemical precipitation separation are presented. The effects of the main operational parameters on the efficiency of purification with these three methods are compared and discussed respectively, and several problems existing in these processes are proposed.     

工业V2O5直接制备纳米颗粒溶胶凝胶

以片状工业V2O5晶体为原料，采用无机途径的溶胶－凝胶法成功地制取了V2O5溶胶和凝胶，测试了V2O5溶胶中颗粒大小，并研究了其粘度和PH值的变化。结果表明：溶胶中V2O5颗粒呈针状，其径向尺寸为50nm-60nm，当V2O5溶胶质量浓度在20g/L以上时极易形成凝胶，其粘度随放置时间增大较快，约10天以后即失去流动性，其PH值也同时发生类似的变化。     

从废钒触媒中回收钒氧化物

介绍了对废钒催化剂采用稀NH4HCO3溶液浸出法获得V2O5和NH4VO3的实验原理及工艺流程，产品纯度可达98%，钒回收率达91%，研究了回收化学反应的规律性及过程特性，为推广工业化生产提供了适宜的工艺参数。     

Semiconducting properties of cold sintered V2O5 ceramics and Co-sintered V2O5-PEDOT:PSS composites

Recently we established a sintering approach, namely Cold Sintering Process (CSP), to densify ceramics and ceramic-polymer composites at extraordinarily low temperatures. In this work, the microstructures and semiconducting properties of V₂O₅ ceramic and (1-x)V₂O₅-xPEDOT:PSS composites cold sintered at 120 °C were investigated. The electrical conductivity (25 °C), activation energy (25 °C), and Seebeck coefficient (50 °C) of V₂O₅ are 4.8 × 10⁻⁴ S/cm, 0.25 eV, and −990 μV/K, respectively. The conduction mechanism was studied using a hopping model. A reversible metal-insulator transition (MIT) was observed with V₂O₅ samples exposed to a N₂ atmosphere, whereas in a vacuum atmosphere, no obvious MIT could be detected. With the addition of 1–2 Vol% PEDOT:PSS, the electrical conductivity (50 °C) dramatically increases from 10⁻⁴ to 10⁻³ ∼ 10⁻² S/cm, and the Seebeck coefficient (50 °C) shifts from −990 to −(600 ∼ 250) μV/K. All the results indicate that CSP may offer a new processing route for the semiconductor electroceramic development without a compromise to the all-important electrical properties.     

Hot corrosion behavior of NdYbZr2O7 exposed to V2O5 and Na2SO4 + V2O5 molten salts

In order to evaluate the application prospects of NdYbZr₂O₇ as a novel TBC material, NdYbZr₂O₇ ceramic was synthesized via a solid-state reaction sintering method, and its hot corrosion behavior exposed to V₂O₅ and Na₂SO₄ + V₂O₅ molten salts at 900 °C, 1000 °C, and 1100 °C was comparatively investigated. For the V₂O₅ salt, the primary corrosion products were granular (Nd,Yb)VO₄ as well as cube-like m-ZrO₂. The corrosion layer consisted of two distinct layers, one of which was Zr-rich layer and another was V-rich layer. In the case of Na₂SO₄ + V₂O₅, NaVO₃, as an intermediate product, played an important role in dissolving the NdYbZr₂O₇ ceramic. Herein, the (Nd,Yb)VO₄ exhibited a rod/plate-like morphology, which could be attributed to the synergistic effect of low driving force and low nucleation rate. Since the molten salt infiltration rate was superior to the pore filling rate throughout the hot corrosion, the thickness of corrosion layer increased with the rise of temperature. The hot corrosion mechanisms of NdYbZr₂O₇ ceramic in various molten salts were discussed based on the phase diagram, Lewis acid-base rule and chemical thermodynamics. On this basis, the NdYbZr₂O₇ coating was prepared by atmospheric plasma spray (APS) and it exhibits a higher corrosion resistance compared to YSZ coating.     

Influence of V2O5 content on ammoxidation of 3-picoline over V2O5/AlF3 catalysts

V₂O₅/AlF₃ catalysts with V₂O₅ loadings ranging from 2 to 15 wt% were prepared by the conventional wet impregnation method, using nonporous AlF₃·3H₂O sample as the support for impregnating NH₄VO₃. It was found that the catalysts evolve porous structures upon calcination at 723 K. The influence of V₂O₅ content was studied on ammoxidation of 3-picoline on the reduced catalysts. The catalyst with 15 wt% V₂O₅ exhibited the highest selective ammoxidation acitivity towards nicotinonitrile. The XRD and oxygen chemisorption studies revealed that vanadia is in a highly dispersed state in the catalysts.     

V2O5-O pacified White Enamels

Whiteness and opacity were developed in lead borosilicate enamels by additions of 3 to 8 weight % of V²O⁵. These enamels were characterized by their fusibility, maturing at 1125° to 1200°F. Compositions were adjusted to provide fit and adherence to both glass and aluminum. Normal methods of preparing, applying, and firing were employed. Some of the experimental enamels for glass had marginal resistance to hot alkali solutions. Others appeared to be suitable for general-purpose enamels, for which the chemical requirements are not so stringent. The enamels for aluminum, for which acid and weather resistance are desirable, were rated as having class A acid resistance, according to the classification system of the Porcelain Enamel Institute.