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Influence of Synthesis Gas Components on Hydrogen Storage Properties of Sodium Aluminium Hexahydride


A systematic study of different ratios of CO, CO2, N2 gas components on the hydrogen storage properties of the Na3AlH6 complex hydride with 4 mol% TiCl3, 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO2in Hand CO, CO2, N2 in Hmixture were investigated. Both CO and CO2gas react with the complex hydride forming Al oxy-compounds, NaOH and Na2CO3 that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus, after 10 cycles with 0.1 vol % CO + 99.9 vol %H2 and 1 vol % CO + 99 vol %H2, the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3%, respectively. In the case of investigation of 10 cycles with 1 vol % CO2 + 99 vol % Hgas mixture, the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H, full degradation was observed, whereas after 6 cycles with 10 vol % CO2+ 90 vol % H2, degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO2+ 27 vol % H+ 61.5 vol % N2, the degradation of 94% after 6 cycles was shown. According to these results, it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.

Funding source: MOST Scientific Project (2018YFE0100700), Guangdong Scientific Project (No. 2017B030314081); GDAS Project of Science and Technology Development (No. 2017GDASCX-0506, 2019GDASYL-0503005); EFRE NRW project funding Nr. EFRE-0800055.

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