Separation of hydrogen from H_2-CO gas mixtures using rare earth hydrogen storage alloy films

稀土储氢合金膜从H_2-CO气体混合物中分离氢气

基本信息

批准号：
01470074
负责人：
ADACHI Gin-ya
金额：
$ 4.99万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01470074/
关键词：
LaNi_5 CaNi_5 Hydrogen separation Amorphous Thin film Hydrogen storage alloy Carbon monoxide LaNi5 EXAFS

项目摘要

The resistance of amorphous LaNi_5 and Ca-Ni alloy films to harmful CO in H_2 gas mixtures has been studied and the H_2-CO gas separation has been performed using these films deposited on a Ni-coated polymer membrane. The hydrogen adsorption capacity of the LaNi_5 films decreased about 30% after exposing to the H_2 gas containing CO. The degree of decrement for the films, however, was much smaller than that reported for a crystalline bulk sample.As the results of separation experiments, hydrogen in the applied gas with a composition of 50 mo1%H_2 - 50 mo1%CO was concentrated to more than 98 mo1% in the permeated gas. The permeation rate for Ni/LaNi_5 films was greater then that for Ni films up to ca. 373 K, but the opposite tendency was observed at above the temperature. The activation energy of hydrogen permeation estimated for the Ni/LaNi_5 film was ca. 30 kJ/mo1H_2 or 14 kJ/mo1H_2 above or below ca. 343 K respectively.CaNi_5 can absorb much hydrogen at low pressures in comparison with LaNi_5. In order to increase the hydrogen permeation rate, the development of hydrogen separation film using the Ca-Ni alloy has been performed. A gas of 50 mo1%H_2 in an applied H_2-CO gas mixtures was concentrated to as high as 99 mo1% in the permeated gas. The permeation rate of the Ni/CaNi_<4.2> film was four times as large as that of the Ni/LaNi_<5.0> film.Thermodynamic data have been evaluated from the hydrogen pressurecomposition isotherms in order to clarify the difference of the local environmental structure around hydrogen atoms in LaNi_<5.0> between the amorphous and crystalline films. The dependence of the relative partial molar enthalpies and entropies of hydrogen on hydrogen concentration in the amorphous film was different from that in the crystalline film. The amorphous film appears to have two types of hydrogen sites. One is influenced by lanthanum, and the other is comprised of more nickel atoms. The hydrogen site in crystalline film is only the former.

研究了非晶LaNi_5和Ca-Ni合金薄膜对H_2气体混合物中有害CO的抵抗力，并利用沉积在镀镍聚合物膜上的这些薄膜进行了H_2-CO气体分离。 LaNi_5薄膜暴露在含CO的H_2气体中后，其氢吸附能力下降了约30%。然而，薄膜的下降程度远小于晶体块状样品的报道。分离实验结果表明，渗透气体中组成为50mo1%H_2-50mo1%CO的施加气体中的氢气浓缩至98mo1%以上。 Ni/LaNi_5 薄膜的渗透速率高于 Ni 薄膜，高达约 100%。 373 K，但在该温度以上观察到相反的趋势。 Ni/LaNi_5 薄膜的氢渗透活化能约为约 30 kJ/mo1H_2 或 14 kJ/mo1H_2 高于或低于分别为343 K。与LaNi_5相比，CaNi_5可以在低压下吸收更多的氢。为了提高氢渗透率，已经进行了使用Ca-Ni合金的氢分离膜的开发。所施加的H_2-CO气体混合物中的50mo1％H_2气体在渗透气体中被浓缩至高达99mo1％。 Ni/CaNi_<4.2>薄膜的渗透速率是Ni/LaNi_<5.0>薄膜的四倍。为了阐明局部环境结构的差异，从氢气压力组成等温线评估了热力学数据。 LaNi_<5.0>中的氢原子周围位于非晶膜和结晶膜之间。非晶膜中氢的相对偏摩尔焓和熵对氢浓度的依赖性与结晶膜中不同。非晶膜似乎具有两种类型的氢位点。一种是受镧的影响，另一种是由更多的镍原子组成。结晶膜中的氢位点只是前者。