Compósitos de poli(éter imida) com partículas nanoestruturadas de LaNi₅ para armazenamento de hidrogênio

Abstract

Hydrogen is a promising energy vector for decarbonizing the energy matrix, but its widespread use requires safe and efficient storage systems. This study aimed to produce microparticles of polyetherimide with LaNi5 through the process of spray drying for hydrogen storage. The LaNi5 ball-milling conditions were optimized, the effects of the polyetherimide layer on H2 sorption were evaluated, microparticles were produced by spray drying with different LaNi5 contents (60, 70, and 80 wt%), and the H2 sorption properties were improved through chemical modification of polyetherimide. Stable and efficient nanostructured composites for hydrogen storage at room temperature were also produced. The results indicated that LaNi5 milling conditions with a weight ratio of milling sphere:particle of 40:1 for 1 hour and rotation of 250 or 350 RPM led to particles with good sorption and morphological properties without amorphization. Polyetherimide was efficient in accommodating LaNi5 particles during hydrogenation cycles without surface defects or metal particle detachment. The microparticles with 70 wt% LaNi5 achieved a maximum capacity of 0.7 %m during activation and about 0.5 %m after activation, requiring 43 s to reach 80% of their maximum capacity. A significant improvement in the H2 sorption kinetics was observed for the composite with 70% LaNi5 and 11.2% degree of sulfonation of polyetherimide, which also showed the best stability in air, reducing the harmful effects observed for the uncoated particle. While the intermetallic compound did not absorb H2 during the first 40 min of the analysis after 7 days of exposure to air, the composite samples reached their maximum capacity in less than 30 min. The microparticles produced by spray drying showed great potential, allowing the manufacture of microparticles with controlled size distribution, possibly kept constant in different cycles.