層狀雙氫氧化物/酚甲醛樹脂複合物之製備及其衍生物在氫氣吸附應用之研究

Synthesis and Characterization of LDH/PF composite and Its Application in Hydrogen Adsorption

謝惠雯(Huei-Wen Hsieh)

指導教授 ： 鄭淑芬

國立臺灣大學/理學院/化學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02402

摘要

本研究將層狀雙氫氧化物 (LDH) 與酚甲醛樹脂 (PF) 進行複合，以酚甲醛樹脂作為碳源，於高溫碳化下，製備出具有高表面積多孔洞材料以進行氫氣吸附之應用。首先比較利用一鍋法及後修飾法 (I) 兩種不同的合成方式形成之複合材料，其中，以XRD結果發現，以鋅鋁層狀雙氫氧化物為前驅物，複合材料在大於900oC碳化溫度時，氧化鋅會被還原成金屬鋅並大量揮發，使材料之表面積及孔洞體積皆會大幅提升，其中又以後修飾法比一鍋法所得之碳材，具有較高表面積以及微孔體積，並在77K, 1atm下具有2.4 wt% 的氫氣吸附量。但因後修飾法 (I) 重複性不高，因此改進成後修飾法 (II)，並改變不同層間陰離子、碳化溫度、鹼催化劑含量、層本身之鋅鋁比等參數，以期得到氫氣吸附量最高之複合材料。最後再藉由改變層本身之金屬離子之組成，探討具有過渡金屬均勻分散之碳材與儲氫效果之關係。本篇所得材料，皆以XRD確認晶型結構， 以TGA測量熱分解溫度及有機物含量，及以BET量測材料的比表面積、孔洞體積。氫氣吸附量則在77 K, 1atm及 298 K, 1*104 kPa下分別量測。結果顯示，當LDH層間為親水性之對氨基苯甲酸根陰離子時，其PF聚合物可部分嵌入層間；以不同鋅鋁比之LDH為前驅物時，則可發現，材料之微孔體積及表面積皆有隨著鋅鋁比值上升而上升之趨勢，顯示金屬鋅在高溫碳化過程中揮發是複合材料產生微孔之重要貢獻。本研究最優化之結果為，以Zn/Al莫爾比為4、對氨基苯甲酸根為陰離子所得之層狀雙氫氧化物為前驅物，在NaOH/phenol莫爾比例為0.1，900oC碳化溫度下所得之複合碳材，具有 663 m2g-1之表面積以及0.31 cm3g-1之微孔體積，於 77 K, 1atm下之氫氣吸附量可達2.0 wt%，相當於每單位面積之氫氣吸附量為3.0*10-3 wt% m-2g-1，高於Park 等人於2012年1，利用鋅為中心金屬簇之IRMOF-8，經碳化後所得之MDC-8之1.39*10-3 wt% m-2g-1。

關鍵字

層狀雙氫氧化物 ； 酚甲醛樹脂 ； 碳材 ； 儲氫材料 ； 金屬有機骨架化合物

並列摘要

n this study, a composite of layer double hydroxide (LDH) and phenolic resol (PF) was prepared, and PF was served as the carbon source through high temperature carbonization to form new carbon composite materials for hydrogen sorption. The LDH/PF composite was prepared by two different routes: one-pot and post-synthesis (I) methods. XRD patterns showed phase transition from zinc oxide to zinc metal with apparent increases in BET surface area and micropore volume of the composite materials after carbonization at temperatures higher than 900oC. In comparison of materials prepared by the two different routes, the carbon composite prepared by post-synthesis (I) gave higher hydrogen uptake of 2.4 wt% under 77 K, 1 atm than that prepared by one-pot method of 1.4 wt%. However, the reproducibility of materials prepared by post-synthesis (I) method was low. An improved method of post-synthesis (II) was developed. Different synthesis parameters in affecting the hydrogen adsorption capabilities of resultant carbon composite materials were examined, including interlayer anions, NaOH/phenol molar ratio, Zn/Al ratio, and partial substitution of Zn by Ni on LDH layer. The composite materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric Analysis (TGA). Hydrogen uptakes were carried out at 77 K, 1 atm as well as 298 K, 1*104 kPa. The results showed that among different interlayer anions only the LDH with p-amino benzoate could have a portion of polymer interchelated in between layers. On the other hand, the micropore volume was found to increase with Zn/Al ratio. The evaporation of metallic zinc during high temperature carbonization was considered the important contribution of production of materials with high surface areas and pore volumes. The material Zn4Al-2pABA-LDH-PF-0.1B-C900 with a surface area of 663 m2g-1 and micropore volume of 0.31 cm3g-1 could uptake 2.0 wt% hydrogen under 77 K, 1 atm. That is equivalent to 3.0*10-3 wt%m-2g-1. The value is higher than that of carbonized MOF-8 (1.39*10-3 m-2g-1) reported by Park and coworkers in the literature1. These results demonstrate that carbon-LDH composite materials have the potential to be promising hydrogen storage material.

並列關鍵字

layered double hydroxide ； phenolic resol ； porous carbon materials ； hydrogen storage ； metal-organic framework (MOF)

參考文獻

47. 劉政樺. 利用層狀雙氫氧化物移除水中的砷酸鹽. 國立台灣大學農業化學碩士論文, 1993.

67. 許哲倫. 鋅鋁層狀雙氫氧化物的合成與鑑定以及其應用於氫氣吸附之探討. 國立台灣大學化學碩士論文, 2011.

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