Synthesis and Investigation of Nano-sized Platinum/Metal Oxide Catalystn Hydrogen Generation from Sodium-borohydride Solution Hydrolysis
Date Issued
2008
Date
2008
Author(s)
Kuo, Heng-Chia
Abstract
Hydrogen energy is being considered as an alternative energy source of the futureecause of its advantages in overcoming the ongoing energy crisis. A hydrogenconomy is proposed to solve the growing shortage of easily obtainable fossil fuel,nd global warming due to the emission of greenhouse gases to the atmosphere. Theost common challenge for hydrogen fuel economy is the storage of hydrogen andhemical hydrides are the best substitute of hydrogen storage system. One of the mostommonly used metal hydride is sodium borohydride, which has a storage density of0.8 wt % for hydrogen and can be used in combination to yield practical generationystem with proper engineering. The alkaline hydrolysis of sodium borohydride isccelerated by using a suitable catalyst such as platinum or ruthenium for achievingigher efficiencies for hydrogen generation. The objective of the present dissertations to study the role of different heterogeneous catalysts to produce hydrogen fromlkaline solutions of sodium borohydride and to understand the kinetics of hydrogeneneration. The Pt supported on Co3O4 (Pt/Co3O4) was synthesized by impregnationethod using H2PtCl6 as precursor for Pt and different ratio of Co3O4/CoO asrecursors for support. During the synthesis process, the polyol reduction was used toonfirm the oxidation of cobalt (II) oxide by H2PtCl6. It was observed that differentt/Co3O4 catalysts show better hydrogen generation efficiencies than the well knownt/LiCoO2 catalyst since platinum in Pt/Co3O4 has more 5d band vacancies. Theydrogen generation activity by using Pt/Co3O4 was decayed after first cycle,owever, it become stable after repeated cycles and can release hydrogen for longereriod. Among the different metal oxides used as a support, the cobalt oxide catalystas shown the best hydrogen generation activity since the catalyst has high electronccepting activity from sodium borohydride. These results are also supported by XRDeasurements of catalysts before and after the hydrogen generation.
Subjects
sodium borohydride
hydrogen generation
catalyst
Type
thesis
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