Sodium Borohydride Hydrolysis as Hydrogen Generator: Issues, State of the Art and Applicability Upstream from a Fuel Cell

Abstract

Today there is a consensus regarding the potential of NaBH4 as a good candidate for hydrogen storage and release via hydrolysis reaction, especially for mobile, portable and niche applications. However as gone through in the present paper two main issues, which are the most investigated throughout the open literature, still avoid NaBH4 to be competitive. The first one is water handling. The second one is the catalytic material used to accelerate the hydrolysis reaction. Both issues are objects of great attentions as it can be noticed throughout the open literature. This review presents and discusses the various strategies which were considered until now by many studies to manage water and to improve catalysts performances (reactivity and durability). Published studies show real improvements and much more efforts might lead to significant overhangs. Nevertheless, the results show that we are still far from envisaging short‐term commercialisation.

Hydrogen generation from NaBH4 hydrolysis using Co-B/AlPO4 and Co-B/bentonite catalysts

“…Noble metals (Pt, Rh, Ru etc.) are found to be the most effective catalysts towards NaBH 4 hydrolysis but their high cost limits their wider use [7,8]. Cobalt-based catalysts, especially cobalt boride alloy (Co-B), have potential catalytic activity to replace noble metals in NaBH 4 hydrolysis [9,10].…”

Dual Role of a Ricinoleic Acid Derivative in the Aqueous Synthesis of Silver Nanoparticles

“…Sodium borohydride [12] is the most widely used reagent for the reduction of metallic ions, despite the fact that most reactions involving it require further safety precautions due to their extreme exothermic nature [13,14]. Additionally, NaBH 4 has to be used in large excess because it undergoes hydrolysis when brought into contact with water and metallic surfaces [15]. N,N-dimethylformamide [16] and hydrazine [17] have also been applied as reducing agents for the production of AgNPs.…”

High volume hydrogen production from the hydrolysis of sodium borohydride using a cobalt catalyst supported on a honeycomb matrix

“…Catalysts employed include noble metal salts (Pt, Rh, Ir, Ru) [1,5,6], non-noble metal salts (Mn, Fe, Co, Ni, Cu) [7e9], and metal borides such as cobalt-boride (CoB), cobaltecobalt boride (CoeCoB) and nickelecobalt boride (NieCoB) which combine excellent catalytic activity with low cost [4,10e14]. The main drawback of the use of such cobalt based catalysts consists in the dramatic loss of activity after only a few operative cycles [10,12,13]. This decrease in activity is believed to be due to the formation of a hydrated salt of sodium metaborate which precipitates and blocks catalytic sites.…”

“…The solubility of sodium metaborate (28 g in 100 g of H 2 O at 25 C) is lower than that of NaBH 4 (55 g in 100 g of H 2 O). In order to avoid this deactivation process an initial NaBH 4 concentration lower than 16 g in 100 g of water is generally used [10,15]. A number of studies have been published dealing with both the catalytic activity and long-term stability of Co 2 eB catalysts doped with either Cr or W [1,4,5,7,13,16,17].…”

“…12 min and is due to the formation of active a Co x B phase from the Co 3 O 4 ; the second phase shows a fast growth of HGR, due to the catalytic activity of the Co x B phase, which reaches a maximum and, finally, during a third period a decrease of HGR is observed due to the depletion of the SBH in the solution. It has also been proposed that in this third phase, the alkaline pH due to the formation of sodium borate, can also lead to the oxidization of the catalyst Co x B to hydrated cobalt hydroxide species [10,18,56,57]. This would justify why the induction period remains in the following cycles.…”