Hydrolysis Of Alkaline NaBH4 Solution Research Articles

Hydrogen generation by hydrolysis of alkaline NaBH4 solution doped with amorphous catalyst Co–Y2O3–B/CNTs

This investigation enhances the catalytic efficiency of Co–B/CNTs for hydrogen production via sodium borohydride hydrolysis by doping with 5%Y2O3. Such doping significantly boosts hydrogen evolution rates, with Co–Y2O3–B/CNTs achieving a production rate of 1083.43 ml g−1·min−1—surpassing Co–B/CNTs by 1.5 times and tripling that of Co–B catalysts. SEM and XRD analyses show Y2O3 doping reduces particle aggregation and maintains the catalyst's amorphous state, thereby increasing the active surface area. Furthermore, XPS analysis demonstrates that introducing yttrium into Co–B/CNTs catalysts improves their surface elemental composition and valence states. This improvement boosts catalyst performance and stability by enhancing electron transfer and particle size optimization. Optimal hydrolysis is achieved at an NaOH concentration of 2.5 mol/L, with higher concentrations diminishing hydrogen production due to increased viscosity from by-product formation. Additionally, Co–Y2O3–B/CNTs catalysts exhibit commendable durability, maintaining more than two-thirds of their initial activity after five reuse cycles, outperforming comparable catalysts to a moderate extent. These findings underscore the beneficial role of Y2O3 in the Co–B/CNTs framework, promoting Y2O3-doped catalysts for their enhanced efficiency, sustainability, and hydrogen production capabilities.

Surface tailored Ru catalyst on magadiite for efficient hydrogen generation

In the present study, a uniformly dispersed, highly durable and efficient ruthenium (Ru) catalyst for hydrogen production was successfully prepared by a facile template method induced by surface-tailored magadiite. The catalyst was systematically characterized and the results revealed that the uniformly dispersed Ru particles with showing an average size of 1.2 nm preferred to anchor on the surface of magadiite, rather than intercalated into the support. Catalytic activity and reutilization of the catalysts were evaluated by evaluating the H2 generation rate (HGR) from an alkaline NaBH4 solution. The maximum HGR at 25 °C reached 59276 ± 500 mL·min−1·g−1 (Ru) with the presence of 3 wt% NaOH and 1 wt% NaBH4. More importantly, the catalytic activity of the reused catalyst still remained 95.7% of the initial HGR after 20 runs. Thus, the catalyst shows high durability and excellent reutilization towards the hydrolysis of alkaline NaBH4 solution. The uniform decoration of Ru particles on magaditte surface is responsible for the high efficiency of the catalyst. This work has revealed that tailoring the distribution of Ru particles on magadiite surface via a simple template method is a promising route for fabricating high-performance hydrogen production catalysts.

Hydrogen Generation from Hydrolysis of Sodium Borohydride Using Nanosized NiB Amorphous Alloy Catalysts

Generation of hydrogen by sodium borohydride solution had attracted lots of attention. A serial of nanosized NiB catalysts were prepared using the chemical reduction method through introducing AlCl3 into the preparation. Catalytic performance of NiB catalysts were investigated in the hydrolysis of alkaline NaBH4 solution. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that NiB catalysts possessed amorphous alloy structure, and the particle size could be adjusted by the AlCl3 amount. Catalytic performance showed that NiB catalyst with smaller particle size had much higher activity. The NiB catalyst also displayed high stability, the catalytic activity could retain about 84% of its initial value after four cycles.

Hydrogen generation from alkaline NaBH4 solution using a dandelion-like Co–Mo–B catalyst supported on carbon cloth

In this study, a dandelion-like Co–Mo–B catalyst was prepared on carbon cloth (CC) by two-step electrodeposition method for the first time. The composition and microscopy are characterized by XRD and SEM technology. The results revealed that the as-synthesized Co–Mo–B catalyst exhibited high hydrogen generation rate (1280.80 mL min−1 g−1) and low activation energy (51.0 kJ mol−1) for the hydrolysis of alkaline NaBH4 solution. The results reveal that the reason might be due to high specific surface of the novel dandelion-like nanostructure and the synergistic effect of Co, Mo and B. Moreover, the catalytic activity was closely related to NaOH concentration, and OH– anions were competitive with BH4– anions in alkaline NaBH4 solution to transfer to the catalyst surface.

Properties of Cu[sbnd]Co[sbnd]P/γ-Al2O3 catalysts for efficient hydrogen generation by hydrolysis of alkaline NaBH4 solution

The catalytic properties of CuCoP/γ-Al2O3 in hydrogen production via sodium borohydride hydrolysis were investigated on aspects of the surface morphology, structure and chemical composition. The characterization methods employed are X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma-atomic emission spectrometer (ICP-AES) and energy dispersive spectroscopy (EDS). The amorphous CuCoP/γ-Al2O3 alloy catalyst was synthesized by electroless deposition. It was found that the as-prepared catalysts exhibited low activation energy (Ea = 47.8 kJ mol−1) and good cycle properties in catalytic hydrolysis of NaBH4 solution. The influences of NaOH and NaBH4 concentration and temperature on hydrogen generation rate (HRG) were also investigated in this paper.

Hydrogen generation from alkaline NaBH4 solution using Co–Ni–Mo–P/γ-Al2O3 catalysts

Co–Ni–Mo–P catalysts were synthesized on the γ-Al2O3 by electroless deposition. The as-prepared Co–Ni–Mo–P/γ-Al2O3 catalysts were characterized by inductively coupled plasma atomic emission spectrometer (ICP-AES), field emission scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption isotherm. The hydrogen generation activity of Co–Ni–Mo–P/γ-Al2O3 catalysts was tested through hydrolysis of sodium borohydride alkaline solution. The concentrations of Na2MoO4, NaOH and NaBH4, electroless deposition time as well as solution temperature were found to have considerable influences on the hydrogen generation rate of hydrolysis of alkaline NaBH4 solution. The results show that the obtained Co–Ni–Mo–P/γ-Al2O3 catalysts exhibit excellent catalytic activity. The hydrogen generation rate increases apparently from 10.125 L min−1 g catalyst−1 to 13.842 L min−1 g catalyst−1 with the concentration of Na2MoO4 increasing from 0.5 g L−1 to 0.8 g L−1 at 45 °C. The catalysts also exhibit favorable cycling performance and lower activation energy (52.43 kJ mol−1) in comparison with that of other reported catalysts.

CoB supported on Ag-activated TiO2 as a highly active catalyst for hydrolysis of alkaline NaBH4 solution

In this study, a series of TiO2 (activated by Ag) supported CoB catalysts were synthesized using electroless deposition method. Compared to the unsupported CoB catalyst, the CoB/Ag–TiO2 catalysts showed much better catalytic activity and higher stability on hydrolysis of NaBH4 in alkaline aqueous solution and the catalysts were insensitive to air oxidation. The optimistic loading amount of CoB was 2.8 wt% and its hydrogen generation rate reached 6294 mL min−1 (g Co)−1 in 1 wt% NaBH4 + 5 wt% NaOH solution at 293 K. The catalytic activity was comparable to some noble catalysts and could retain nearly 70% after 5 cycles. The catalysts were studied by varies techniques and the results revealed that the dispersion of CoB was improved and the CoB/Ag–TiO2 catalysts possessed distinct porous structure which could promote the diffusion of reactants/products. The surface composition and the electron transfer effects between the Co0 with B0 and Ag0 could also affect the catalytic activity. Under the current experimental conditions, the specific activation energy of 2.8CoB/Ag–TiO2 catalyst was determined as 44 kJ mol−1 and the kinetic equation was also deduced.

Preparation of polyvinylidene fluoride–nickel hollow fiber catalytic membranes for hydrogen generation from sodium borohydride

Polyvinylidene fluoride hollow fiber catalytic membranes (CMs) are prepared by in situ reduction of nickel salt with sodium borohydride (NaBH4). The CMs and their membrane modules are both used for hydrogen generation from alkaline NaBH4 solution. Characterization of this nickel-based catalytic membrane is carried out by using various techniques, such as scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The rate of hydrogen generation from catalytic hydrolysis of alkaline NaBH4 solution is determined by varying the temperature, concentration of NaBH4 and sodium hydroxide (NaOH), and content of catalyst. In general, the rate of hydrogen generation is about 388.8mLmin−1m−2 CMs in 20mL of 1.0wt.% NaBH4 and 0.5wt.% NaOH aqueous solution at 30°C. It can be efficiently cycled and reused more than six times without significant loss of the catalytic activity. The optimum treated conditions for CMs are 20wt.% NaOH, 0.2M NiCl2, and 1M NaBH4 aqueous solution. The activation energy of NaBH4 hydrolysis reaction is noticed about 55.3kJmol−1.

Electroless Deposition of Low-Cost Reusable Transition Metal Active Catalyst on Oxide Supports for Hydrogen Generation from Hydrides

Catalytic hydrolysis of alkaline NaBH4 solution and ammonia borane using electroless-based transition metal catalysts have been studied. The transition metal catalysts were synthesized by Pd catalyzation and activation of Al2O3 or TiO2 substrates and subsequent electroless plating of the transition metals. Results will be presented on the effect of Pd loading, annealing temperature of the catalyst, electroless plating time on the catalyst activity for hydrogen generations. Kinetic data of the hydrolysis reaction will also be discussed.

Promoted Mo incorporated Co–Ru–B catalyst for fast hydrolysis of NaBH4 in alkaline solutions

Quaternary alloyed catalyst of Mo incorporated Co–Ru–B has been synthesized with chemical reduction method using ethylene glycol solution. The effect of doped-Mo and the solvent in preparation process on morphology features which look like irregular nanoflowers and fish scales was observed. The performance of catalyst towards hydrolysis of alkaline NaBH4 solution for hydrogen generation depends on the Mo concentration. When the molar ratio χMo is up to 30%, the Mo incorporated Co–Ru–B catalyst synthesized in ethylene glycol have the highest catalytic activity of 8075 mL min−1 g−1, which is higher than that by some binary or ternary alloy catalysts in previous reports. The effects of NaOH and NaBH4 concentration as well as the reaction temperature on hydrolysis of NaBH4 by optimal Mo incorporated Co–Ru–B catalyst have also been studied. The activity energy was measured to be 48.8 kJ mol−1, which is lower than 64.87 kJ mol−1 obtained from pure Co–B catalyst.

Optimizing preparation of carbon supported cobalt catalyst for hydrogen generation from NaBH4 hydrolysis

Modified carbon-supported cobalt catalysts have been synthesized by optimization of the preparation conditions including ball-milling pretreatment of the carbon and screening the solvents used for synthesis of the catalysts. Ball-milling treatment on carbon can not only reduce its particle size but also functionalize the surface with oxygen-containing groups, resulting in good affinity to Co2+ ions. The non-aqueous solvent N,N-dimethylformamide (DMF) is beneficial to improve the immersional wetting and adsorption of the cobalt salt solution on the surface of carbon, leading to uniform deposition of cobalt nanoparticles upon chemical reduction. The carbon-supported cobalt catalyst with the Co loading of 13.20wt% obtained under optimum conditions exhibits excellent catalytic activity toward NaBH4 hydrolysis and the average hydrogen generation rate at 27°C is 10.29LH2min-1g(cobalt)-1 corresponding to a turnover frequency of 1473.4molH2(molcobalt)−1h−1, which is higher than the most reported data. Furthermore, the effects of the cobalt loading, catalyst dosage, concentration of NaOH and NaBH4, and reaction temperature on the hydrogen generation have been investigated by hydrolysis of alkaline NaBH4 solution, and the corresponding rate equation can be described as r=Aexp(-42190/RT)[cobalt]0.16[NaOH]0.23[NaBH4]0.30.

Hydrogen generation by hydrolysis of alkaline NaBH4 solution on Co–Mo–Pd–B amorphous catalyst with efficient catalytic properties

Mo-modified Co–Pd–B (Co–Mo–Pd–B) and Pd-modified Co–B (Co–Pd–B) catalyst powders are synthesized by chemical reduction of cobalt and molybdenum salt at ambient conditions. The resulting catalyst powders are characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-photoelectron spectroscopy (XPS) and BET surface area measurement. The study on the catalytic efficiency of amorphous Co–Mo–Pd–B catalyst powders is performed in hydrogen generation by hydrolysis of alkaline sodium borohydride (NaBH4). The Co–Mo–Pd–B powders show the highest hydrogen generation rate as compared to Co–B, Co–Mo–B, and Co–Pd–B catalyst powders. Kinetic studies on the hydrolysis reaction of NaBH4 with Co–Mo–Pd–B catalyst reveal that the concentrations of both NaBH4 and NaOH have essentially no evident effects on hydrogen generation rate. The promoting effect of Mo in Co–Mo–Pd–B catalyst results in lower activation energy for hydrogen production, which is 36.36kJmol−1 compared to 64.87kJmol−1 obtained with pure Co–B powder.

Hydrogen generation by hydrolysis of alkaline NaBH4 solution with Cr-promoted Co–B amorphous catalyst

Cr-modified Co–B (Co–Cr–B) catalyst alloy powders have been synthesized by chemical reduction of cobalt and chromium salt at room temperature to study the hydrogen production by catalytic hydrolysis of NaBH4. The Cr/Co molar ratio was varied in the catalyst in order to study the effect of Cr doping on surface modification and catalytic efficiency of Co–B catalyst. The resulting catalyst powders were characterized by scanning electron microscopy, X-ray diffraction, X-photoelectron spectroscopy, and BET surface area measurement. When the molar ratio χCr=Cr/(Cr+Co) exceeds 9% the BET surface area of the Co–Cr–B catalyst increases by one order of magnitude as compared to that of Co–B catalyst. The catalytic activity of the Co–Cr–B for hydrogen production depends on Cr concentration: specifically, the activity increases by increasing χCr up to about 4% and then it gradually decreases by further increasing χCr. We established that the increased catalytic activity is related to the formation of chromium oxide on the catalyst surface, with the oxide favoring the dispersion of Co–B particles resulting in high catalyst surface area. However as χCr exceeds 4%, Cr starts to cover the Co active sites and the corresponding catalytic activity decreases. The highest catalytic activity was obtained at the optimum Cr-content, χCr=4%, in Co–Cr–B catalyst, showing nearly 4 times higher H2 generation rate than that of pure Co–B catalyst. Kinetic studies on the hydrolysis reaction of NaBH4 with Co–Cr–B catalyst reveal that the concentrations of both NaBH4 and NaOH have essentially no effects on hydrogen generation rate. The promoting effect of Cr in Co–Cr–B catalyst results in lower activation energy for hydrogen production, which is 37kJmol−1 as compared to 45kJmol−1 obtained with pure Co–B powder. Finally, the possible role of Cr3+ species in the electron exchange mechanisms involved in NaBH4 hydrolysis with the Co–Cr–B catalyst has been discussed.

Preparation of magnetic cobalt-based catalyst for hydrogen generation from alkaline NaBH4 solution

A fast and simple fabrication process, viz. a wet-chemical reduction process, was utilized for preparation of a cobalt-based catalyst to be used for hydrogen generation from alkaline NaBH4 solution. Characteristics of this cobalt-based catalyst were carried out by using various instruments, such as SEM/EDS, XPS, ICP, VSM, BET and TGA. The surface chemistry of the obtained catalyst is mainly cobalt oxides, not cobalt borides. Ferromagnetic property of the cobalt-based catalyst makes it convenient for being recycled from spent NaBH4 solution. The rate of hydrogen generation from catalyzed hydrolysis of alkaline NaBH4 solution was determined as a function of temperature, NaBH4 concentration, and NaOH concentration in the presence of prepared catalysts. In general, stable generation rate of highly pure hydrogen near 200mLmin−1g−1 was achieved in 100mL of 5wt% NaBH4 solution containing 5wt% NaOH solution and 200mg of Co/IR-120 catalyst, in which no temperature runoff was observed during the course of hydrogen production. The activation energy of NaBH4 hydrolysis reaction was found at 66.67kJmol−1, which was comparable with others reported in the open literatures.

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 -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/-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. © 2006 Elsevier B.V. All rights reserved.

Effects of Electroless Deposited Co-P Catalysts on the Hydrogen Generation Properties from Hydrolysis of Alkaline NaBH4 Solution

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