乙酸加氢制备乙醇的催化剂(续)

<正>(上接第8期第42页)[084]合适的金属前躯体包括,金属卤化物,可被胺溶解的金属氢氧化物,金属硝酸盐,金属草酸盐。例如,合适的金属钯、铂前驱体就有氯铂酸、氯铂酸按、能被胺溶解的氢氧化铂、硝酸铂、硝酸铂胺、氯化铂、草酸铂、硝酸钯、四面体硝酸钯胺、氯化钯、草酸钯、氯化铂钠、氯化钯钠。通常无论从经济还是环     

从废钯催化剂中提取氯化钯

本文阐述了利用废钯催化剂,经焚烧、王水溶解、氨水除铁、酸析、焙烧等制取氯化钯的工艺流程及其生产方法。该工艺简单,成本低,总回收率>85%,纯度>99%。     

反式-双（三苯基膦）二氯合钯（Ⅱ）的合成及其结构表征

以二氯化钯为原料,以无水乙醇为溶剂,直接与三苯基膦回流反应,制备反式．双（三苯基膦）二氯合钯（Ⅱ）,通过元素分析、红外光谱分析、核磁共振谱表征了其化学结构。本合成方法的产率〉98％,产品质量分数〉99．0％,适合工业化生产要求。     

水／有机两相中氯化钯催化α-蒎烯加氢反应的研究

将氯化钯溶解于水中用于催化α-蒎烯水／有机两相加氢反应。考察了反应温度、反应时间、反应压力、氯化钯用量和水的用量对反应的影响。得到了较佳的工艺条件：α-蒎烯10g、反应温度180℃、反应时间5h、反应压力5MPa、氯化钯3mg、水10g。在此工艺条件下顺式蒎烷的收率为99．7％,而氯化钯所在的水相不经过任何处理重复使用3次催化活性不变。     

粗铂中钯的分离方法

粗铂经王水溶解，赶硝，加入丁二酮肟使大部分钯以沉淀的形式与铂分离，余留的少量钯用溴酸钠水解法处理，可达到铂钯分离的目的，所得纯铂品位高于99．95％。     

化学镀用钯—锡活化剂

本试验是一种评价影响钯—锡活化液性能的定量因素的新试验。在本试验中,比较了溶解的铜、氯化亚锡和活性钯的浓度与活化液的特性。在试验中特意用减小活化液稳定性的办法来加速活化液失效。实验的结果表明,盐基活化液比酸基活化液要好。钯—锡活化液是在化学镀之前用来催化非导体镀件。活性钯具有胶体的性质,用高浓度的二价锡作抗絮凝剂使之稳定。用卤化物,最好是氯化物来防止亚锡水解。浓缩活化液是用氯化亚锡和氯化钯之间的相互的化学作用来制备。实际上,在浓缩液中含有零价的钯、氯     

钯/活性炭催化剂中贵金属钯的回收

研究了废钯/活性炭催化剂中金属钯的回收。将废钯/活性炭催化剂用高温焙烧的方法除去其中大部分炭,钯渣用甲酸还原后用王水浸出。考察了焙烧、还原及浸出条件对钯回收率的影响,得到的氯化钯回收率95%,纯度99%。     

α-Al2O3多孔陶瓷上化学镀Pd膜工艺研究

用浸渍–高温还原法活化和化学镀法在α-Al2O3多孔陶瓷上制备了Pd膜。主要考察了浸渍法的改善、肼加入方式、化学镀温度、氯化钯浓度对钯复合膜微观结构的影响。研究结果表明:超声波的应用可以改善活化;肼的分批加入可以改善钯膜的质量;温度60°C、氯化钯质量浓度2.0g/L较适宜;钯膜的微观结构为竖直或斜方向类柱状沉积层。     

从催化氧化法葡萄糖酸钠废催化剂中回收氯化钯的研究

本文介绍了从催化氧化法葡萄糖酸钠废催化剂中回收氯化钯的原理和步骤 ,试验钯的回收率可达99 0 %以上 ,回收后的氯化钯可以返回再用来制备Pd/C催化剂 ,能减低葡萄糖酸钠产品成本 10 %。     

对胶体钯的实践及认识

胶体钯活化液是美国学者Shipley于1961年首先研究成功的,它的催化活性和由此获得的化学镀层与非金属基体的结合力远优于敏化——活化两步法,取得了极其广泛的应用。胶体钯活化液的组成一般为: 氯化钯氯化亚锡盐酸(37％) 锡酸钠 1g/l 75～80g/l 300ml/l 7g/l Shipley的胶体钯活化液(也叫酸基型胶体钯)含有大量的盐酸,使用时工作条件差又污染了环境,因而提出了用氯化钠代替大部分盐而配制了盐基型胶体钯。这样便大大地改善     

Separation of Palladium and Silver from a Nitric Acid Solution by Liquid Surfactant Membranes

Abstract

The recovery of palladium from a nitric acid solution containing silver has been conducted by application of liquid surfactant membranes (LSMs) containing LIX 860, a β-hydroxyoxime, as a mobile carrier in a stirred tank. The extraction equilibria of palladium and silver using several different extractants were also studied. Palladium was selectively extracted from a silver-containing liquor with LIX 860 while it was also observed that both palladium and silver were extractable with a sulfur-containing extractant. The recovery of palladium with LIX 860 was selectively achieved by using perchloric acid solution as the LSM internal phase dosed with thiourea. In the LSM operation, the effects of several chemical parameters on the selective recovery of palladium were studied. The use of hydrochloric acid as an internal receiving phase prevented the transport of silver into the emulsion due to the formation of silver chloride in the external feed solution. Commercially available Span 80 was found suitable for the selective extraction of palladium as a surfactant in LSM operation. Under optimum conditions, palladium was successfully separated from silver and concentrated into a receiving phase in W/O emulsions.     

Treatment of tissue paper containing radioactive waste and electrochemical recovery of valuables using ionic liquids

Dissolution of tissue paper waste containing valuable contaminants such as uranium and palladium in 1-butyl-3-methylimidazolium chloride (bmimCl) has been studied. Dissolution of 5-7 wt.% tissue paper in bmimCl is complete within 60 min at 373 K and the time required for dissolution increases with increase of loading. It is difficult to dissolve more than 10 wt.% tissue paper in bmimCl and the limiting solubility of tissue paper is 15-17 wt.% at 373 K. Uranium(VI) and Pd(II) in chloride/nitrate form dissolve in bmimCl along with tissue paper. The electrochemical behaviour of uranium(VI) and palladium(II) in the resultant solution in the presence and absence of a co-solvent, DMSO, has been investigated by transient voltammetric techniques at glassy carbon working electrode and the diffusion coefficients have been determined. Electrolysis of a solution of uranium(VI) and palladium(II) loaded tissue paper in bmimCl results in deposition of uranium oxide (UO₂) and metallic palladium, respectively, which were characterized by X-ray diffraction and scanning electron microscopy. The study established the possibility of dissolving tissue paper and other cellulose based materials containing soluble uranium(VI) and Pd(II) compounds in bmimCl, and their recovery from the resultant solution. Cellulose pulp can be regenerated by adding surplus water after the recovery of valuables and the ionic liquid, bmimCl, can be regenerated for further use by vacuum distillation of DMSO and water.     

Studies on the Sorption of Palladium using Cross‐Linked Poly (4‐Vinylpyridine‐Divinylbenzene) Resins in Nitric Acid Medium

Various cross‐linked (4, 8, and 12%) gel‐type weak‐base poly(4‐vinylpyridine) (PVP) resins were studied for palladium recovery from nitric acid medium. The sorption of palladium was found to decrease with an increase in cross‐linkage of the resin. 8 and 12% PVP resins exhibited maximum D _Pd(II) values at 2–6 M HNO₃, whereas 4% PVP resin showed maximum D _Pd(II) values at lower acidities (0.1 M HNO₃). FT‐IR, SEM, and XPS techniques were used for the characterization of palladium‐loaded resins. Detailed studies were carried out with the resin of modest cross‐linkage i.e., 8% PVP resin. The sorption isotherm studies revealed that the maximum palladium loading approaches the theoretical capacity of the resin, presuming the sorption of palladium as divalent anion at 4 M HNO₃. The pseudo‐second order kinetics model yielded the best fit for the experimental data of sorption kinetics. An increase in temperature accelerates the rate of palladium extraction and also the addition of chloride ions increases the palladium uptake. Column studies were performed using 4 and 8% PVP resins in 2 and 4 M nitric acid concentrations. The loaded palladium could be eluted efficiently with acidic thiourea solution.     

镍网上无氰镀银-钯合金工艺

研究了一种氯化物无氰电镀Ag-Pd合金工艺,通过正交试验得出最佳配方及工艺条件:氯化锂520 g/L,氯化钯1.31 g/L,硝酸银3.11 g/L,添加剂为0.05 g/L硫脲和0.2 g/L氯化镍,pH 为2.0,温度60℃,阴极电流密度0.15 A/dm2.测试表明,该镀液性能稳定,分散能力为86.75％,覆盖能...     

Electrowinning of palladium using a modified cyclone reactor

The electrochemical behaviour of palladium in dilute acidic chloride solution was investigated using a rotating disc electrode system and the electrowinning of palladium using a modified electrochemical cyclone cell was also carried out. The effect of several variables such as applied voltage, hydrochloric acid concentration and electrolyte flow rate were studied to obtain the optimum conditions for electrowinning. More than 99% of the palladium in solution was recovered within an hour under the optimum conditions using the cyclone cell and grey powdery deposits were observed at a high applied voltage. The purity of palladium electrowon from the leach liquor was at least 99%.     

The use of a rotating cylinder electrode to selective recover palladium from acid solutions used to manufacture automotive catalytic converters

The reduction of palladium, rhodium and neodymium ions at concentrations of 0.94, 0.97 and 0.69 mol dm⁻³, respectively was studied in 1 mol dm⁻³ HNO₃ or 1 mol dm⁻³ HCl, at a stainless steel and a vitreous carbon electrode, at 25 °C. At a vitreous carbon electrode in a solution containing rhodium and palladium ions in 1 mol dm⁻³ HCl electrolyte, the reduction of metal ions occurred at a similar potential to the formation of hydrogen gas, which impeded the selective separation of the two metals. At a stainless steel cathode in 1 mol dm⁻³ HNO₃, palladium deposition occurred at a potential ≈0.35 V less negative than that of rhodium allowing the selective recovery of palladium. Neodymium ions were not electroactive in acidic chloride or nitrate media at pH 0. Using a solution obtained from a catalytic converter manufacturer containing palladium, rhodium and neodymium ions in 1 mol dm⁻³ HNO₃, palladium ions were preferentially removed at 0.15 V versus SHE at an average cumulative current efficiency of 57%.     

温控钯-膦配合物催化油酸甲酯加氢反应的研究

制备了具有温控功能的膦配体脂肪醇聚氧乙烯醚氯化亚磷酸邻苯二酚酯(OPGPP),用FTIR、1HNMR对其结构进行了表征,将其与氯化钯的配合物用于催化油酸甲酯的加氢反应。考察了反应时间、反应温度、氢气压力、催化剂用量对反应的影响。在反应温度200℃,氢气压力7MPa,PdCl2用量为油酸甲酯质量的0.12%,n(PdCl2)∶n(OPGPP)=1∶10,反应时间4h的较佳反应条件下,加氢产物的羟值为114,碘值为25。对催化剂的重复使用性能进行了考察,该催化体系不经处理重复使用4次后,所得产物的羟值、碘值分别为102和27。