Synthesis of Aluminum hydroxide and its application on the Hydrogen Generation of Al/water reaction

• Main Authors: Mei-Hung Chen, 陳美宏
• Other Authors: Hong-Wen Wang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5ujqw9

碩士 === 中原大學 === 化學研究所 === 106 === The thesis reports the synthesis of aluminum hydroxide using different chemical solutions. The most effective catalyst synthesized in this study is S4 series. The particles of S5 series are around 30~100 nm under SEM observation. When these catalysts are used in hydrogen generation using Al:Al(OH)3:H2O = 1:1:200 system, the reaction is completed within 90 mins. It would be wise to recycle the used Al(OH)3 due to the consideration of cost and environment. The commercial Al(OH)3 with gibbsite phase (1-5 μm) was dissolved in NaOH and re-precipitated in HCl to catalyze the reaction of Al/water for hydrogen generation. The reprecipitated Al(OH)3 is less than 200 nm. The hydrogen generation is 100% within 2 h using such reprecipiated Al(OH)3 in Al : Al(OH)3:H2O =1:1:200 system. Then, use hydrochloric acid to produce the new aluminum hydroxide (<200nm), and 100% hydrogen generation in two hours in a system of Al : Al(OH)3:H2O =1:1:200. The recycled reaction product, Al(OH)3 (different particle sizes), after hydrogen generation was also redissolved and reprecipitated using above method. The new reprecipitated Al(OH)3 was around 100~800 nm and generated 100% hydrogen in 7 hours in Al : Al(OH)3:H2O =1:1:200 system. We have also tested different Al sources for hydrogen generation. These are aluminum scrap (1-4 mm), aluminum powder (12m), and aluminum blocks (2*2*2 cm3). Both 1:1:200 and 1:3:10 systems for Al:Al(OH)3:H2O were tested. It was found that aluminum scrap with aluminum hydroxide can generate 100% hydrogen in 10 minutes. Strong base solution is required to generate hydrogen efficiently when Al blocks were used. The Al powders stored for more than 10 years can not generation 100% hydrogen in a reasonable time due to thick oxide layer.