Hydrogen generation by sodium borohydride hydrolysis on nanosized CoB catalysts supported on TiO2, Al2O3 and CeO2

A series of nanosized CoB catalysts supported on TiO₂, Al₂O₃, and CeO₂ were prepared. The catalysts were prepared by incipient-wetness impregnation. The sample was dried at 100 °C and then dispersed in water and reduced by an aqueous solution of sodium borohydrate at room temperature. An unsupported CoB cluster was used for comparison. The activities of the supported CoB catalysts were higher than that of unsupported one. The reaction rates of these supported CoB catalysts decreased in the order: CoB/TiO₂ > CoB/Al₂O₃ > CoB/CeO₂ > unsupported CoB. The reaction kinetics on various catalysts was also investigated.     

Highly efficient acid-treated cobalt catalyst for hydrogen generation from NaBH4 hydrolysis

The effect of cobalt-based catalysts, i.e. CoCl₂(20 wt% Co)/Al₂O₃ treated by different acids, on NaBH₄ hydrolysis was investigated. Five acids were used: oxalic acid, citric acid, acetic acid, sulfuric acid and hydrochloric acid. Two ways of acid treatment were considered: (i) ex-situ addition of acid to CoCl₂(20 wt% Co)/Al₂O₃ at room temperature and (ii) in-situ addition by mixing CoCl₂, Al₂O₃ and acid (one-step process). Both ways showed that adding an acid to the catalyst contributed to an important increase of the catalytic activity towards the NaBH₄ hydrolysis. The best performances were obtained with the catalysts treated with either HCl or CH₃COOH as the global activity of CoCl₂(20 wt% Co)/Al₂O₃ was increased up to 50%.     

Investigation on salisylaldimine-Ni complex catalyst as an alternative to increasing the performance of catalytic hydrolysis of sodium borohydride

In this study, 5-amino-2, 4-dichlorophenol-3, 5-ditertbutylsalisylaldimine-Ni complex catalyst is synthesised and used as an alternative to previous studies to produce hydrogen from hydrolysis of sodium borohydride. The resulting complex catalyst is characterised by XRD, XPS, SEM, FT-IR and BET surface area analyses. Experimental works are carried out at 30 °C with 2% NaBH₄, 7% NaOH and 5 mg of catalyst. The maximum hydrogen production rate from hydrolysis of sodium borohydride with nickel-based complex catalyst compared to the pure nickel catalyst is increased from 772 ml min^?1g^?1 to 2240 ml min^?1g^?1 by an increase of 190%. At the same time, the hydrolysis reaction with pure nickel catalyst is completed in 145 min while the hydrolysis reaction with nickel-based complex catalyst is completed in 50 min. The activation energy of this hydrolysis reaction was calculated as 18.16 kJ mol^?1. This work also includes kinetic information for the hydrolysis of NaBH₄.The reusability of the nickel-based complex catalyst used in this study has also been studied. The nickel-based complex catalyst is maintained the activity of 72% after the sixth use, compared to the first catalytic use.     

Electrospun carbon nanofiber-encapsulated NiS nanoparticles as an efficient catalyst for hydrogen production from hydrolysis of sodium borohydride

Carbon nanofibers (CNFs) incorporating NiS nanoparticles (NPs), namely NiS@CNFs were prepared by one-step electrospinning and successfully employed as a catalyst for hydrogen production from hydrolytic dehydrogenation of sodium borohydride (SBH). As-prepared NiS@CNFs, composed of polyacrylonitrile (PAN), nickel acetate, and ammonium sulfide, was calcined at 900 °C in argon atmosphere, and characterized using standard surface science techniques. The combined results revealed the growth of NiS NPs inside the CNFs, hence confirmed the presence of elemental Ni, S, and C. The as-prepared NiS@CNFs catalyst has a significantly higher surface area (650.92 m²/g) than the reported value of 376 m²/g. Importantly, this catalyst exhibited a much higher catalytic performance, for H₂ production from SBH, than that of Ni@CNFs, as evidenced by its low activation energy (∼25.11576 kJ/mol) and their R_max values of 2962 vs. 1770 mL/g·min. Recyclability tests on using NiS@CNFs catalyst showed quantitatively production (∼100% conversion) of H₂ from SBH and retained up to 70% of its initial catalytic activity after five successive cycles. The low cost and high catalytic performance of the designed NiS@CNFs catalyst enable facile H₂ production from readily available hydrogen storage materials.     

Exploring the technological maturity of hydrogen production by hydrolysis of sodium borohydride

Sodium borohydride NaBH₄ (SB) has been rediscovered in the late 1990s and been presented as a promising hydrogen storage material owing to its high gravimetric hydrogen density of 10.8 wt% and ability to produce H₂ by hydrolysis at ambient conditions. This looked promising, but soon hydrolysis of SB encountered numerous obstacles. In 2015, a progress report (Int J Hydrogen Energy 2015; 40:2673–91) showed that the 2000–2014 research did not overcome all of the obstacles, making SB far from being technologically mature. Eight years have passed since 2015. Have we put more effort into all aspects relating to hydrolysis of SB? If so, do we have produced scaled-up technologies and prototypes, of which we would have a better knowledge? Have we been able to gain in technological readiness level? Answering these questions is the main objective of this article. A secondary objective is to summarize the newly acquired knowledge. Five main observations stand out. First, the 2015–2022 period is regrettably similar to the 2000–2014 since, again, catalysts have dominated the field and the other aspects (e.g. recycling of the by-product to regenerate SB, scale-up and implementation) have received little attention. Second, hydrolysis of SB still runs into numerous obstacles, some of the obstacles being known since a long time and other ones being relatively new and unknown. Third, there has been little gain in terms of technological readiness level while few research groups have shown that there is room for new ideas and innovation. Fourth, energy, exergy and economic analyses are needed to evaluate the overall cost of H₂ from SB. Fifth, SB has not effectively thought from the end user perspective. In conclusion, many obstacles remain to be overcome before hydrolysis of SB can be a commercial solution for carrying and producing H₂. However, all efforts should be dedicated to (i) construct, operate and optimize H₂ production systems (i.e. prototypes and demonstrators), (ii) handle SB at the gram-to-kilogram scale, (iii) make production of SB even more efficient, and (iv) overcome all obstacles while thinking from the end user perspective.     

Co3O4 hollow fiber: An efficient catalyst precursor for hydrolysis of sodium borohydride to generate hydrogen

Sodium borohydride (NaBH₄) is one of promising hydrogen storage materials for practical application, and the development of high-efficient catalysts for NaBH₄ hydrolysis to generate hydrogen is of critical importance. In this communication, Co₃O₄ hollow fiber composed of nanoparticles array was served as catalyst precursor and facilely prepared by combustion method with template of the absorbent cotton. For characterization, FE-SEM, HRTEM, EDS, XRD, FTIR and ICP were applied, respectively, and typical water-displacement method was performed to evaluate the catalytic activity. Using a solution composed of 10 wt% NaBH₄ and 2 wt% NaOH, hydrogen generation rate was up to 11.12 L min^?1 g^?1 (25 °C), which is much higher than that of the commercial cobalt oxides and similar catalyst precursors reported in literature.     

A highly active Co-B catalyst for hydrogen generation from sodium borohydride hydrolysis

Co-B catalysts were prepared by the chemical reduction of CoCl₂ with NaBH₄ for hydrogen generation from borohydride hydrolysis. The catalytic properties of the Co-B catalysts were found to be sensitive to the preparation conditions including pH of the NaBH₄ solution and mixing manner of the precursors. A Co-B catalyst with a very high catalytic activity was obtained through the formation of a colloidal Co(OH)₂ intermediate. The ultra-fine particle size of 10 nm accounted for its super activity for hydrogen generation with a maximum rate of 26 L min⁻¹ g⁻¹ at 30 °C. The catalyst also changed the hydrolysis kinetics from zero-order to first-order.     

Synthesis of Ni/TiO2 catalyst by sol-gel method for hydrogen production from sodium borohydride

Hydrogen is a sustainable, renewable and clean energy carrier that meets the increasing energy demand. Pure hydrogen is produced by the hydrolysis of sodium borohydride (NaBH₄) using a catalyst. In this study, Ni/TiO₂ catalysts were synthesized by the sol-gel technique and characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) methods. The effects of Ni loading ratio (20–40%), catalyst amount (75–200 mg), the concentration of sodium hydroxide (NaOH, 0.25–1 M), initial amount of NaBH₄ (75–125 mg) and the reaction temperature (20–60 °C) on hydrogen production performance were examined. The hydrogen yield (100%) and hydrogen production rate (110.87 mL/g_cat.min) were determined at the reaction conditions of 5 mL of 0.25 M NaOH, 100 mg NaBH₄, 100 mg Ni/TiO₂, 60 °C. Reaction order and activation energy were calculated as 0.08 and 25.11 kJ/mol, respectively.     

Sustainable hydrogen production by catalytic hydrolysis of alkaline sodium borohydride solution using recyclable Co-Co2B and Ni-Ni3B nanocomposites

In this article, we report Co-Co₂B and Ni-Ni₃B nanocomposites as catalyst for hydrogen generation from alkaline sodium borohydride. Kinetic studies of the hydrolysis of sodium borohydride with Co-Co₂B and Ni-Ni₃B nanocomposites reveal that the concentration of NaBH₄ has no effect on the rate of hydrogen generation. Hydrolysis was found to be first order with respect to the concentration of catalyst. The catalytic activity of Co-Co₂B was found to be much higher than that of Ni-Ni₃B as inferred from the activation energies 35.245 KJ/mol and 55.810 kJ/mol, respectively. Co-Co₂B nanocomposites were found to be more magnetic than Ni-Ni₃B. These catalysts showed superior recyclability with almost the similar catalytic activities for several hydrolytic cycles supporting the principles of sustainability. Co-Co₂B catalyst showed hydrogen generation rate of about 4300 mL/min/g which is comparable to most of the reported good catalysts till date.     

Thermo-economic analysis of a hydrogen production system by sodium borohydride (NaBH4)

In the spectrum of current energy possibilities, hydrogen represents a solution of great interest toward a future sustainable energy system. No single technology can sustain the energy needs of the whole society, but integration and hybridization are two key strategic features for viable energy production based in hydrogen economy.In the present work, a hydrogen energy model is analyzed. In this model hydrogen is produced through the electrolysis of water, taking advantage of the electrical energy produced by a renewable generator (photovoltaic panels). The produced hydrogen is chemically stored by the synthesis of sodium borohydride (NaBH₄). NaBH₄ promising features in terms of safety and high volumetric density are exploited for transportation to a remote site where hydrogen is released from NaBH₄ hydrolysis and used for energy production.This model is compared from an economic standpoint with the traditional hydrogen storage and transportation technology (compressed hydrogen in tanks).This paper presents a thermodynamic and economic analysis of the process in order to determine its economic feasibility. Data employed for the realization of the model have been gathered from recent important progresses made on the subject.The innovative plant including NaBH₄ synthesis and transportation is compared from an economic standpoint with the traditional hydrogen storage and transportation technology (compressed hydrogen in tanks). As a final point, the best technology and the components' optimal sizes are evaluated for both cases in order to minimize production costs.     

Hydrogen generation by hydrolysis of sodium borohydride on CoB/SiO2 catalyst

Generation of hydrogen by hydrolysis of alkali metal hydrides has attracted attention. Unsupported CoB catalyst demonstrated high activity for the catalytic hydrolysis of NaBH₄ solution. However, unsupported CoB nanoparticles were easy to aggregate and difficult to reuse. To overcome these drawbacks, CoB/SiO₂ was prepared and tested for this reaction. Cobalt (II) acetate precursor was loaded onto the SiO₂ support by incipient-wetness impregnation method. After drying at 100 °C, Co cations were deposited on the support. The dried sample was then dispersed in methanol/water solution and then fully reduced by NaBH₄ at room temperature. The catalyst was characterized by N₂ sorption, XRD and XPS. The results indicated that the CoB on SiO₂ possessed amorphous structure. B and Co existed both in elemental and oxidized states. SiO₂ not only affected the surface compositions of CoB, but also affected the electronic states of Co and B. B⁰ could donate partial electron to Co⁰. The structure effect caused by the SiO₂ support helped to prevent CoB nanocluster from aggregation and therefore the activity increased significantly on hydrolysis of alkaline NaBH₄ solution. The CoB/SiO₂ catalyst showed much higher activity than the unsupported CoB catalyst. At 298 K, the hydrogen generation rate on CoB/SiO₂ catalyst was 4 times more than that on the unsupported CoB catalyst. The hydrogen generation rate was as high as 10,586 mL min⁻¹ g⁻¹ catalyst at 298 K. CoB/SiO₂ is a very promising catalyst for this reaction.     

Research progress on catalysts for hydrogen generation through sodium borohydride alcoholysis

Hydrogen is a promising energy carrier for realizing the transition from fossil fuels to renewable energy sources. Nowadays, the development of the hydrogen economy faces many challenges connected with its efficient production, storage, distribution, and end-use. During the past decade, the alcoholysis, particularly methanolysis, of sodium borohydride (NaBH₄) has attracted much attention due to the nonflammability, nontoxicity, potential for utilization in cold conditions of the reaction system. Highly efficient catalysts are of great significance to guarantee the efficiency of the reaction and control the hydrogen release. In this review, we summarize recent advances in both metallic and nonmetallic catalysts for the alcoholysis of NaBH₄. This review also summarizes the advantages and disadvantages of various catalysts in the investigations to assess the potential opportunities and challenges for their application in NaBH₄ methanolysis. The catalytic mechanisms related to NaBH₄ methanolysis were also discussed.     

Anchored cobalt film as stable supported catalyst for hydrolysis of sodium borohydride for chemical hydrogen storage

Electrodeposition was used to deposit cobalt over polycarbonate membrane (PCM), which was used as stable supported catalyst in hydrolysis of sodium borohydride NaBH₄. We selected PCM as support owing to its lightness, easy handling, stability, and porous structure with nanosized channels. Our primary objective was to obtain a catalytic film resistant to both physical degradation and delamination while H₂ bubbled on its surface. A thin film consisting of mushroom-like cobalt nanoarchitectures were prepared. By SEM, we observed that it is strongly embedded into the PCM thickness, with the anchoring occurring through the channels. This shaped catalyst was mechanically stable and did not show degradation during the reaction. The main results are reported and discussed in details herein.     

Effects of crystallinity and morphology of solution combustion synthesized Co3O4 as a catalyst precursor in hydrolysis of sodium borohydride

Solution combustion synthesized (SCS) cobalt oxide (Co₃O₄) powder has been studied as a catalyst precursor for the hydrolysis of sodium borohydride (NaBH₄). Synthesis is completed in less than two minutes and results indicate SCS is capable of reproducibly synthesizing 98.5–99.5% pure Co₃O₄ nano-foam materials. SCS materials demonstrate an as-synthesized specific surface area of 24 m² g⁻¹, a crystallite size of 15.5 nm, and fine surface structures on the order of 4 nm. Despite having similar initial surface areas and sample purities, SCS-Co₃O₄ outperforms commercially available Co₃O₄ and elemental cobalt (Co) nano powders when used as a catalyst precursor for NaBH₄ hydrolysis. Hydrogen generation rates (HGR) using 0.6 wt% NaBH₄ in aqueous solution at 20 °C were observed to be 1.24 ± 0.2 L min⁻¹ g_cat⁻¹ for SCS nano-foam Co₃O₄ compared to 0.90 ± 0.09 and 0.43 ± 0.04 L min⁻¹ g_cat⁻¹ for commercially available Co₃O₄ and Co, respectively. The high catalytic activity of SCS-Co₃O₄ is attributed to its nano-foam morphology and crystallinity. During the hydrolysis of NaBH₄, the SCS-Co₃O₄ converts in-situ to an amorphous active catalyst with a specific surface area of 92 m² g⁻¹ and exhibits a honeycomb type morphology.     

Hydrogen generation utilizing alkaline sodium borohydride solution and supported cobalt catalyst

Supported Co catalysts with different supports were prepared for hydrogen generation (HG) from catalytic hydrolysis of alkaline sodium borohydride solution. As a result, we found that a γ-Al₂O₃ supported Co catalyst was very effective because of its special structure. A maximum HG rate of 220 mL min⁻¹ g⁻¹ catalyst and approximately 100% efficiency at 303 K were achieved using a Co/γ-Al₂O₃ catalyst containing 9 wt.% Co. The catalyst has quick response and good durability to the hydrolysis of alkaline NaBH₄ solution. It is feasible to use this catalyst in hydrogen generators with stabilized NaBH₄ solutions to provide on-site hydrogen with desired rate for mobile applications, such as proton exchange membrane fuel cell (PEMFC) systems.     

Hydrogen generation from sodium borohydride solution using a ruthenium supported on graphite catalyst

The catalyst with high activity and durability plays a crucial role in the hydrogen generation systems for the portable fuel cell generators. In the present study, a ruthenium supported on graphite catalyst (Ru/G) for hydrogen generation from sodium borohydride (NaBH₄) solution is prepared by a modified impregnation method. This is done by surface pretreatment with NH₂ functionalization via silanization, followed by adsorption of Ru (III) ion onto the surface, and then reduced by a reducing agent. The obtained catalyst is characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Very uniform Ru nanoparticles with sizes of about 10 nm are chemically bonded on the graphite surface. The hydrolysis kinetics measurements show that the concentrations of NaBH₄ and NaOH all exert considerable influence on the catalytic activity of Ru/G catalyst towards the hydrolysis reaction of NaBH₄. A hydrogen generation rate of 32.3 L min⁻¹ g⁻¹ (Ru) in a 10 wt.% NaBH₄ + 5 wt.% NaOH solution has been achieved, which is comparable to other noble catalysts that have been reported.     

Kinetics of hydrolysis of sodium borohydride for hydrogen production in fuel cell applications: A review

Hydrogen generation from the hydrolysis of sodium borohydride (NaBH₄) solution has drawn much attention since early 2000s, due to its high theoretical hydrogen storage capacity (10.8 wt%) and potentially safe operation. However, hydrolysis of NaBH₄ for hydrogen generation is a complex process, which is influenced by factors such as catalyst performance, NaBH₄ concentration, stabilizer concentration, reaction temperature, complex kinetics and excess water requirement. All of these limit the hydrogen storage capacities of NaBH₄, whose practical application, however, has not yet reached a scientific and technical maturity. Despite extensive efforts, the kinetics of NaBH₄ hydrolysis reaction is not fully understood. Therefore, better understanding of the kinetics of hydrolysis reaction and development of a reliable kinetic model is a field of great importance in the study of NaBH₄ based hydrogen generation system. This review summarizes in detail the extensive literature on kinetics of hydrolysis of aqueous NaBH₄ solution.     

Highly active heteropolyanions supported Co catalysts for fast hydrogen generation in NaBH4 hydrolysis

This paper reports on the use of Co supported catalyst for the hydrolysis of NaBH₄. Various materials with different acid/base surface properties have been chosen as supports (hydrotalcites, KF/Al₂O₃, heteropolyanions). The supports and the Co-containing catalysts were characterized by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, nitrogen adsorption. The NaBH₄ hydrolysis reaction was studied in a liquid phase calorimeter coupled with a gas counter in order to follow at the same time the kinetics and the heat of reaction. Co supported on heteropolyanions showed great results in terms of reaction rate. Cobalt dispersed on heteropolyanions is a real promising catalytic system for the development of hydrogen generation in PEM fuel cells for portable devices.     

The effects of operating conditions on hydrogen production from sodium borohydride using Box-Wilson optimization technique

Sodium borohydride is the most investigated boron compound among hydrogen-carrier materials by researchers because of its stable structure, relatively high hydrogen storage capacity (NaBH₄, 10.8% hydrogen by weighing), comparatively cost-efficiency, and non-flammability. This study aims to produce hydrogen from sodium borohydride solution whose hydrolysis was carried out both in the absence of any catalysts at above 100 °C. In order to increase the rate of hydrogen production using NaBH₄ solution, the initial concentration of HCl and temperature were optimized using the Box- Wilson method. The field of the highest dehydrogenation yield was shown by drawing contour plot for the second order model. As a result of the experiments, the highest dehydrogenation yield (100%) of this solution was achieved in 3.76 M HCl concentration and at 157 °C; besides, the reaction time was the least under these conditions.