Mechanochemical production of hydrogen carriers
Sodiumborohydride (NaBH4) is regarded as one of the options to store and transport hydrogen safely and at relatively high energy density. Large quantities of hydrogen gas can easily be released when the sodiumborohydride powder is dissolved in water and brought in contact with a catalyst. One of the bottlenecks hampering large scale application is the difficult regeneration of the spent fuel (sodiummetaborate) which remains after this hydroysis reaction. Mechanochemical conversion with magnesium or magnesiumhydride may offer a solution, but until now focus has always been on the chemical component of mechanochemistry.
Together with his supervisors Johan Padding and Dingena Schott, PhD student Santiago Garrido Nuñez has performed for the first time a systematic study of the influence of various mechanical parameters (such as the rotational speed and amplitude of the milling jar, milling time, milling ball diameter, and filling level) on the chemical conversion, finding that a high yield of 90% may be achieved at reduced energy costs compared to previous literature results.
Abstract
In this study we investigate the mechanochemical regeneration of sodium borohydride (NaBH4) from a system comprising hydrated sodium metaborate (NaBO2-4H2O) and magnesium hydride (MgH2). We explore the individual and joint impact of key operational parameters (rotational speed, milling time, ball-to-powder ratio (BPR), and molar ratio) on the regeneration yield. Furthermore, a method for quantifying chemical conversion is introduced relying only on water and thus, offering environmental benefits. This approach additionally facilitates the production and storage of a “ready-to-use” NaBH4 solution with minimal losses at room temperature. Notably, a yield of 90% is achieved, with a 20% reduction in rotational speed compared to prior literature. This research contributes to sustainable hydrogen storage and presents practical advancements in mechanochemical processes.
Santiago Garrido Nuñez
Dingena L. Schott
