Characteristics of Al Alloy as a Material for Hydrolysis Reactor of NaBH₄

Abstract

요 약NaBH 4 가수 분해용 경량반응기의 재질로서 알루미늄 합금을 검토하였다. 알루미늄은 알칼리에 용해되는데, NaBH 4 반응 용액중에 안정화제로 NaOH가 포함되어 있다. 알루미늄의 부식 속도를 낮추기 위해서 NaOH 농도를 낮추면 저 장중에 NaBH 4 가 손실된다. 그래서 최적의 NaOH 농도를 결정할 때 알루미늄 부식과 NaBH 4 안정화를 모두 고려해야 한다. NaBH 4 안정화와 알루미늄 부식속도는 수소발생속도에 의해 측정하였다. Abstract − Aluminum alloy was examined as a material of low weight reactor for hydrolysis of NaBH 4. Aluminum is dissolved with alkali, but there is NaOH as a stabilizer in NaBH 4 solution. To decrease corrosion rate of aluminum, decrease NaOH concentration and this result in loss of NaBH 4 during storage of NaBH 4 solution. Therefore stability of NaBH 4 and corrosion of aluminum should be considered in determining the optimum NaOH concentration. NaBH 4 stability and corrosion rate of aluminum were measured by hydrogen evolution rate. NaBH 4 stability was tested at 20~50 o C and aluminum corrosion was measured at 60~90 o C. The optimum concentration of NaOH was 0.3 wt%, considering both NaBH 4 stability and aluminun corrosion.

Exploring the technological maturity of hydrogen production by hydrolysis of sodium borohydride

“…Nevertheless, it must be admitted that the Lapena-Rey et al's study clearly underlines how critical the issues are when SB is used at the gram-to-kilogram scale. Other issues were reported elsewhere (Table 2) [100,108,111,112]. One of them is specific to the aircraft applications as it is about the importance of keeping stable the center of gravity of the plane even when the SB tank is depleted [100].…”

“…Another issue is related to the alkaline pH values (up to 12) that are reached upon hydrolysis of SB and/or when the solution is stabilized with NaOH. Corrosion is likely to occur with stainless steel [108] and is unavoidable with aluminum alloys [111]. Coating of the internal walls of reactors will thus be required for long-term utilizations.…”

“…One of the main challenges is just to make the system lighter without compromising security. Unavoidable degradation of the reactor [111] Stainless-steel mini-reactor Use of stainless steel Negative impact on the gravimetric hydrogen storage capacities [112] There are few other articles including simulation works that are worth being briefly mentioned. Tomoda et al [113] used a reactor simulation model to simulate hydrolysis of an aqueous alkaline solution of SB at 90 °C.…”

“…Other issues to be encountered by H 2 production systems and reactors, as reported in references[100,108,111,112].…”