2022-11-102024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/649719由於其催化性能，鉑（platinum，Pt）和鈀（palladium，Pd）為汽車催化轉化器中的重要鉑族元素（platinum group metals，PGMs），主要用於將有害排放物（如碳氫化物、一氧化碳和氮氧化物）轉化為危害較小的排放物（如二氧化碳、水蒸氣和氮氣）排出。由於其稀貴性及開採短缺，導致Pt和Pd的價格大幅上漲，如此凸顯了汽車催化轉化器中Pt和Pd回收的重要性。因Pt和Pd特性相似，現有文獻大多同時吸附之，而本計畫以「選擇性吸附」及「選擇性脫附」為主要策略進行Pt和Pd的捕捉、分離及純化。聚醯胺6（polyamide 6，PA6）又稱尼龍6，其聚合物富含大量的氮元素，對Pt及Pd的親和性相當高，惟其比表面積及多孔性不足；有鑑於此，本計畫將藉由發泡程序製備多孔性較高的發泡PA6（FPA6），並在其發泡過程中添加活性碳以製備PA6/活性碳複合材料（FPA6/AC），使材料的比表面積達到最大化。 第一年計畫旨在測試市售PA6顆粒對模擬溶出液中Pt(IV)與Pd(II)之吸附能力並探討其吸附路徑，首要工作為分析市售PA6顆粒物化特性並以批次吸附實驗在不同操作參數下測試該顆粒於模擬溶出液中對Pt(IV)與Pd(II)之吸附能力。藉由表面分析結果、吸附動力模擬、等溫吸附曲線擬合及吸附熱計算探討可能吸附機制。第二年計畫之目的在於測試不同合成參數（Na2CO3濃度及活性碳劑量）下所製備的FPA6及FPA6/AC於模擬溶出液中對Pt(IV)與Pd(II)之吸附能力並探討其吸附路徑，觀察合成參數對該複合材料物化特性之影響，並以批次吸附實驗在不同操作參數下測試該顆粒於模擬溶出液中對Pt(IV)與Pd(II)之吸附能力，最終彙整兩年研究成果並提出整體吸附機制。第三年計畫之目的在於探討不同脫附劑（HCl、thiourea及HCl/thiourea）及脫附劑濃度對吸附劑上Pt(IV)與Pd(II)之選擇性脫附影響。主要以吸附飽和之吸附劑進行批次脫附實驗，探討不同脫附劑濃度比及時間序列對Pt(IV)與Pd(II)之脫附先後順序及速率。最終整合三年研究成果，提出全面性的「吸/脫附路徑」及完整的「Pt與Pd純化/分離策略」。 PA6、FPA6及FPA6/AC吸附材的成功開發可降低廢觸媒轉換器上PGMs的回收難度與成本，建立更多商機，促使更多業者投入觸媒轉換器的回收工作，減緩當前Pt與Pd資源短缺之困境。本三年期計畫成果預期可提升整體PGMs吸附/脫附知識與技術水平，整體貢獻領域包含「化學工程」、「材料科學」、「環境工程」及「循環經濟」等領域。 Due to their catalytic properties, platinum group metals (PGMs) platinum (Pt) and palladium (Pd) are often installed in car catalytic converters to convert harmful emissions (i.e., HC, CO, and NOx) into less harmful emissions (i. e., CO2, H2O, and N2). However, due to their scarcity and resource shortage, prices of Pt and Pd have been markedly increasing, highlighting the importance of Pt and Pd recovery. Due to the similar characteristics of Pt and Pd, they are extremely difficult to be separated/purified from a solution; as such, previous works have mainly focused on the adsorption of both metals simultaneously from an eluted catalyst solution. In this project, the combination of “selective adsorption” and “selective desorption” are the major strategies for the capture, separation, and purification of Pt and Pd. Polyamide 6 (PA6), also called nylon 6, is a polymer containing numerous nitrogenous groups with a high affinity towards Pt and Pd, but poor specific surface area and porosity. This project aims to improve the porosity of the PA6 structure via a foaming process to prepare foamed PA6 (FPA6), and maximize specific surface area through addition of activated carbon (AC) during the foaming process, creating an FPA6/AC composite. In the first year of the project, the commercial PA6 will be physically/chemically characterized and examined for its Pt(IV)/Pd(II) adsorption capability at various conditions; adsorption kinetics, isotherms, and thermodynamics studies are further conducted to investigate the possible adsorption mechanism. In the second year of this project, the various FPA6 and FPA6/AC samples will be synthesized per different affecting parameters (i.e., Na2CO3 concentration and AC dosage). In addition, these samples will also be characterized, and their Pt(IV)/Pd(II) adsorption capabilities examined at various conditions for understanding the effects of synthetic parameters. The adsorption data will be used to fit the adsorption kinetic equations and isothermal models, and calculate thermodynamic parameters. The entire adsorption mechanism can be proposed from the findings of these two years’ work. The third year of the project aims to understand the effects of various desorption agents (i.e., HCl, thiourea, and HCl/thiourea) and agent concentrations on selective Pt(IV)/Pd(II) desorption. Batch desorption experiments will be conducted with Pt(IV)/Pd(II)-saturated adsorbents to test desorption efficiency, desorption sequence, and desorption rate. The completed “adsorption/desorption mechanism” and comprehensive “Pt/Pd separation/purification strategy” can ultimately be provided according to the summarized findings from the three years’ experimental results. PA6, FPA6, and FPA6/AC developments are significant because they can save costs in PGMs extraction, and alleviate difficulty in PGMs recovery. Overall, outcomes of this project will contribute to fields of chemical engineering, materials science, environmental engineering, and circular economy, providing new knowledge regarding adsorption/desorption processes and applications for capturing Pt(IV) and Pd(II) in realistic settings.鉑;汽車觸媒轉化器;吸附;脫附;platinum; palladium; car catalyst converter; adsorption; desorption