自廢觸媒中分離與純化鈀之研究

A Study on the Separation and Purification of Palladium from Spent Pd/C Catalyst

楊福泉(Fu-Chang Yung)

指導教授 ： 蔡德華

國立臺北科技大學/工程學院/化學工程研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00456

摘要

本研究以廢鈀觸媒做為實驗對象，從中分離並純化出金屬鈀。實驗主要分為三部分來探討，而一開始的廢鈀觸媒需先經過通氧鍛燒以去除活性碳和有機物。第一部分為浸出實驗，用簡單且對環境無污染的實驗流程來溶解廢鈀/活性碳觸媒。實驗結果顯示，在90℃、液固比20、加熱2小時下，20% HCl +35% H2O2浸出廢鈀觸媒，鈀的浸出率可達98.4%。
第二部分為分離實驗，利用溶劑萃取法來作為分離方法，將Aliquat336溶於煤油中來萃取浸出液中的鈀。實驗中發現，萃取過程中會產生第三相的問題，影響萃取的效果，但當加入正辛醇時，可消除第三相的產生。最後實驗結果顯示，以0.05M Aliquat336+10%1-Octanol為載體，油水相比為1，在H2O2+HCl的系統下，可有效的萃取鈀金屬，萃取率高達99%以上；以0.5molL-1HCl+0.5molL-1 thiourea水溶液進行反萃，反萃率可達100%。實驗最後藉由圖解分析法可得知萃合物組成為PdCl4(R4N)2，其萃取平衡常數分別為K20=3178.04
第三部分為還原實驗，實驗結果顯示，在pH值在1-9之間 、90℃、反應時間1小時下，0.1mL的甲酸可還原0.0108M鈀水溶液達99%以上。然而溫度和pH值對還原鈀粉的影響甚大，在較高的溫度和pH值下，不僅能提高回收率，更能大幅的減少甲酸的用量。最後，本研究提供了一有效的回收流程，可使鈀從廢鈀觸媒中有效的分離出來，其鈀純度可達99.96%。

關鍵字

鈀 ； 廢觸媒 ； 分離 ； 萃取 ； 反萃取 ； 氯化三辛基甲基銨(Aliquat336)

並列摘要

In this research, We used spent catalyst to separate and purification for palladium, The experiment was divided into three parts. Spent catalyst were initially pre-oxidized (800℃,2hr) in order to eliminate active carbon and organic matter.The first part is leaching process, A simple and environmentally friendly process was propose for the recovery of palladium from spent catalyst based on carbon carrier. It’s about 98.4% dissolution of palladium was achieved by leaching with a solution contains 20%HCl and 35%H2O2 at 90 ℃ for 2.5 hr with a liquid/solid ratio of 20/1 .
The second part is separation process, Liquid-Liquid extraction(LLE) of palladium(II) in H2O2+HCl solution has been investigated, using Aliquat336 in kerosene at 25℃. The result show that the third phase formed when extracting palladium in H2O2+HCl solution with Aliquat336.But if the modifier (1-Octanol) was added in the extractant, this phenomenon will be eliminated. The results indicate that,0.05M Aliquat 336+10% 1-Octanol extracted more than 99% of palladium in one stage at 25℃ with an A/O phase ratio equal to 1 (v/v) , 0.5molL-1+0.5molL-1thiourea systyem is better for the palladium stripping, it was stripped about 100% in one stage at 25℃ with an A/O phase ratio equal to 1 (v/v). In the extraction process, there have about two Aliquat336 molecules involved in the aqueous solution. Based on graphical and numberical analysis.The compositions of Pd/Aliquat336 complex formed in the organic phase were found to be PdCl4(R4N)2, and the respective correspomding equilibrium constant were K20=3178.04
The third part is reduction process, the results show that, at pH 1-9 and temperature 90 ℃, reaction time 1hour, 0.0108 M Pd2+, simply use 0.1 mL formic acid, will can be more than 99% recovery ratio. The temperature and pH value on the recovery of palladium powder has great impact, at higher pH and temperature, not only can increase the recovery efficiency and reaction rate, more significantly reduce the amount of formic acid.Finally, We provide an efficient and complete separation of palladium process, this recovery process can achieve about 99.96% purity of palladium from spent Pd/C catalyst.

並列關鍵字

Palladium ； Spent Catalyst ； Separation ； Extraction ； Stripping ； trioctylmethylammonium Chloride(Aliquat336)

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