硼氫化鈉產氫之奈米白金/氧化物載體觸媒合成與 特性研究

Synthesis and Investigation of Nano-sized Platinum/Metal Oxide Catalyst in Hydrogen Generation from Sodium-borohydride Solution Hydrolysis

郭恆嘉(Heng-Chia Kuo)

指導教授 ： 劉如熹

國立臺灣大學/理學院/化學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01184

摘要

對於氫能經濟而言，目標之ㄧ即是用以取代汽油，成為運輸工具之最佳燃
料。其中氫氣來源與貯氫材料開發乃為將氫能應用於運輸工具之關鍵技術。硼氫
化鈉乃為氫能經濟重要之材料，其可穩定存在鹼性水溶液二至三個月，氫氣重量
密度高達10.8 wt.%，可克服貯氫材料單位重量中氫氣含量過低之問題；亦可藉
由觸媒水解即時產生氫氣，克服氫氣輸出之問題，且可藉由特定觸媒提升氫氣生
成速率，故乃為極重要氫能經濟之材料。
本研究乃著重於硼氫化鈉產氫之奈米金屬/氧化物載體觸媒之合成與特性研
究，探討白金與各類金屬氧化物為載體合成觸媒對於硼氫化鈉產生氫氣速率之影
響。其中白金扮演傳導電子之角色；載體方面，易接受電子能力將大幅影響觸媒
活性；能力高者，如鈷之氧化物，觸媒活性極佳；能力低者，觸媒活性差。以鈷
之氧化物為載體之觸媒活性極高，然而經一次產氫後觸媒結構崩解，導致觸媒活
性大幅下降。而研究結果亦顯示可以鈷金屬為硼氫化鈉產氫觸媒，此舉將有助於
開發更經濟之硼氫化鈉燃料電池系統。
本研究藉由多種分析技術探討硼氫化鈉水解產氫反應特性與觸媒結構探
討。分析方法包括：以X光粉末繞射法(X-ray diffraction；XRD) 鑑定觸媒晶體結
構；以穿透式電子顯微鏡(transmission electron microscopy；TEM)進行樣品形貌
與粒徑大小分布分析；以X光吸收光譜(X-ray absorption spectroscopy；XAS)之X
光吸收邊緣結構(X-ray absorption near edge structure；XANES)鑑定樣品元素之價
數與電子結構； 以感應耦合電漿原子發射光譜儀(inductively coupled
plasma-atomic emission spectrometer；ICP-AES)鑑定白金含量。

關鍵字

硼氫化鈉 ； 產氫系統 ； 鉑-四氧化三鈷

並列摘要

Hydrogen energy is being considered as an alternative energy source of the future
because of its advantages in overcoming the ongoing energy crisis. A hydrogen
economy is proposed to solve the growing shortage of easily obtainable fossil fuel,
and global warming due to the emission of greenhouse gases to the atmosphere. The
most common challenge for hydrogen fuel economy is the storage of hydrogen and
chemical hydrides are the best substitute of hydrogen storage system. One of the most
commonly used metal hydride is sodium borohydride, which has a storage density of
10.8 wt % for hydrogen and can be used in combination to yield practical generation
system with proper engineering. The alkaline hydrolysis of sodium borohydride is
accelerated by using a suitable catalyst such as platinum or ruthenium for achieving
higher efficiencies for hydrogen generation. The objective of the present dissertation
is to study the role of different heterogeneous catalysts to produce hydrogen from
alkaline solutions of sodium borohydride and to understand the kinetics of hydrogen
generation. The Pt supported on Co3O4 (Pt/Co3O4) was synthesized by impregnation
method using H2PtCl6 as precursor for Pt and different ratio of Co3O4/CoO as
precursors for support. During the synthesis process, the polyol reduction was used to
confirm the oxidation of cobalt (II) oxide by H2PtCl6. It was observed that different
Pt/Co3O4 catalysts show better hydrogen generation efficiencies than the well known
Pt/LiCoO2 catalyst since platinum in Pt/Co3O4 has more 5d band vacancies. The
hydrogen generation activity by using Pt/Co3O4 was decayed after first cycle,
however, it become stable after repeated cycles and can release hydrogen for longer
period. Among the different metal oxides used as a support, the cobalt oxide catalyst
has shown the best hydrogen generation activity since the catalyst has high electron
accepting activity from sodium borohydride. These results are also supported by XRD
measurements of catalysts before and after the hydrogen generation.

並列關鍵字

sodium borohydride ； hydrogen generation ； catalyst

參考文獻

transportation vehicles. Mrs Bulletin 2008, 33, (4), 439-444.

Physics Today 2004, 57, (12), 39-44.

Hayashi, H., Hydrogen generation using sodium borohydride solution and metal catalyst

coated on metal oxide. International Journal of Hydrogen Energy 2002, 27, (10),

5. Kojima, Y.; Suzuki, K.; Kawai, Y., Hydrogen generation from lithium borohydride