Chenxi Wu,Huajun Lai,Feng Wang,Dianhui Wang,Weijiang Gan,Yulai She,Zhongmin Wang
V-based alloy membranes have huge potential for hydrogen separation and purification due to their higher hydrogen permeability , but suffer from hydrogen embrittlement . To address this matter, Pd and Fe have been chosen as alloying additions in V-based membranes to inhibit hydrogen embrittlement and maintain high hydrogen permeation performance based on the lattice-matching strategy. The phase structure, composition, microstructure and hydrogen permeation properties of V-Pd-Fe ternary alloy are investigated systematically, and the V-Fe and V-Pd binary alloys are presented for comparison. The results show that the prepared V-Pd-Fe ternary can match almost perfectly with pure V in lattice constants . Attributing to the lattice-matching strategy, the V-Pd-Fe ternary alloy exhibits more excellent hydrogen permeable properties than that of V-Fe and V-Pd binary alloys . The reduction of hydrogen embrittlement is ascribed to the lower hydrogen solubility that induced by the lattice distortion and electronegativity of Fe and Pd. Meanwhile, the manipulated lattice constant that parallel to pure V maintains high hydrogen permeation performance. Additionally, the designed ternary V 87.8 Pd 8 Fe 4.2 alloy exhibits exceptional long-term hydrogen permeation stability at 573 and 623 K, and hydrogen flux gradually decreases at 673 and 723 K is observed due to the interdiffusion between Pd film and V 87.8 Pd 8 Fe 4.2 substrate and defects in the Pd coating. This study offers new scenario and method for optimized hydrogen permeable properties and restrains hydrogen embrittlement in the alloy membrane.
The density and viscosity of ferric chloride/trioctylmethylammonium chloride ionic liquid ( r FeCl 3 /[A336]Cl) with different molar ratios ( r = 0.1–0.8) of FeCl 3 to [A336]Cl were measured at temperatures from 313.15 to 358.15 K and atmospheric pressure. The density and viscosity data were fitted by the relevant temperature variation equations, respectively. The variation of density and viscosity with temperature and r was obtained. The solubility of r FeCl 3 /[A336]Cl to H 2 S was measured at temperatures from 318.15 to 348.15 K and pressures from 0 to 150 kPa. The effects of temperature, pressure, and r on the solubility of H 2 S were discussed. The reaction equilibrium thermodynamic model (RETM) was used to fit the H 2 S solubility data, and the average relative error was less than 1.3%, indicating that the model can relate the solubility data well. And Henry's constant and chemical reaction equilibrium constant were obtained by the RETM fitting. The relationships of Henry's constant and chemical reaction equilibrium constant with temperature and r were analyzed.
The density, viscosity, and hydrogen sulfide solubility of the triethylamine hydrochloride ferric chloride ionic liquid (rFeCl3/Et3NHCl) were measured at temperatures of 303.15 to 348.15 K, pressures up to 200 kPa, and iron–amine ratios (r, molar ratio of anhydrous FeCl3 to Et3NHCl) of 0.4 to 1.0 mol·mol–1. Density and viscosity data were respectively fitted with empirical correlations for temperature. The H2S solubility in rFeCl3/Et3NHCl was measured by the isochoric pressure drop method. The absorption of H2S in FeCl3/Et3NHCl contains the physical process and chemical process. The decrease in temperature and iron–amine ratio and the increase in pressure are beneficial to improve the total solubility of H2S. Using the reaction equilibrium thermodynamic model (RETM) to correlate the solubility data, the chemical reaction equilibrium constant and Henry’s constant were obtained. Affected by the molecular molar volume and acidity, Henry’s constant first decreases and then increases with the increase in iron–amine ratio and has a minimum value at 0.6 molar ratio. The reaction equilibrium constant decreases with the rise of iron–amine ratio and the reduction of temperature. The total solubility at low pressure is dominated by chemical absorption. As the pressure increases, the proportion of physical absorption increases.
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