Catalytic Hydrolysis Of Sodium Borohydride Research Articles

Hydrogen production through hydrolysis of sodium borohydride: Oleic acid stabilized Co–La–Zr–B nanoparticle as a novel catalyst

OL (Oleic acid)–Cobalt–Lanthanum–Zirconium–Boron nanoparticle was synthesized by chemical reduction of chloride salts of metals in the presence of oleic acid as stabilizing agent. The obtained materials were characterized by XRD (X-ray diffraction), TEM (Transmission electron microscopy), ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), BET (Brunauer–Emmett–Teller) and UV–vis (Ultraviolet–visible) techniques. XRD pattern declares that under Argon atmosphere only metal boride phase has been crystallized and it is not seen any oxide phase of metals. TEM image depicts there are not form any agglomerated nanoparticle. Particle size distribution was prepared and average size particle is about 25 nm. OL stabilized Co–La–Zr–B nanoparticle is active for hydrogen generation from the hydrolysis of sodium borohydride. The reported work also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (Ea = 51.24 kJ mol−1) and effects of the catalyst dosage, amount of substrate, and temperature on the rate for the catalytic hydrolysis of sodium borohydride. Catalytic hydrolysis of NaBH4 is first order with respect to the catalyst concentration and also first order to the NaBH4 concentration in the case of OL stabilized Co–La–Zr–B nanoparticles.

Hydrogen generation from hydrolysis of sodium borohydride by cubic Co–La–Zr–B nano particles as novel catalyst

Cubic Co–La–Zr–B nano particles were prepared in situ for the first time from the reduction of Co(II), La(III) and Zr(IV) chloride by sodium borohydride in methanol under reflux condition. Poly N-vinyl-2-pyrrolidone (PVP) as stabilizing agent was used for preparation of Co–La–Zr–B nano particles. Obtained powders were characterized by XRD, BET, ICP, SEM, TEM and UV–vis techniques. XRD patterns declare that under argon atmosphere only metalboride phase has been crystallized and it was not seen any oxide phase of metals. TEM image depicts that PVP stabilized nano particles are square shaped particles that containing many nanoclusters. Cubic Co–La–Zr–B nano particles were also confirmed by SEM image. Co–La–Zr–B is highly active catalysts for hydrogen generation from the hydrolysis of sodium borohydride. The reported work also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (Ea = 53 kJ mol−1) and effects of the catalyst dosage, amount of NaBH4, and temperature on the rate of the catalytic hydrolysis of sodium borohydride. Catalytic hydrolysis of NaBH4 is first order with respect to the catalyst concentration and also first order to the NaBH4 concentration in the case of cubic Co–La–Zr–B nano particles.

Synthesis and characterization of Co–La–Zr–B quaternary amorphous nano alloy: Kinetic study for hydrogen generation from hydrolysis of sodium borohydride

Abstract Co–La–Zr–B quaternary amorphous nano alloy was for the first time prepared in situ ultrasound-assisted reduction of Co(II), La(III) and Zr(IV) chloride by sodium borohydride aqueous solution. Obtained powder was characterized by XRD, BET, ICP, FE-SEM and TEM techniques. No distinct peak could be observed in XRD pattern of the obtained alloy indicating that the Co–La–Zr–B possessed amorphous structure. Regarding to the size, SEM and TEM images depict that the most of particles are lower than 10 nm and there is no significant aggregation. Co–La–Zr–B nano alloy is highly active catalysts for hydrogen generation from the hydrolysis of sodium borohydride. The reported work also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy ( E a = 60.06 kJ mol −1 ) and effects of the catalyst dosage, amount of substrate, and temperature on the rate for the catalytic hydrolysis of sodium borohydride. Catalytic hydrolysis of NaBH 4 is first order with respect to the catalyst concentration and zero order respect to the NaBH 4 concentration in the case of Co–La–Zr–B quaternary amorphous nano alloy.

Hydrogen Generation from the Catalytic Hydrolysis of Sodium Borohydride Using Nanostructured Pt-Ni, Pt-Cu and Pt-Co Catalysts Supported on the Titanium Surface

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Kinetics of hydrogen generation from hydrolysis of sodium borohydride on Pt/C catalyst in a flow reactor

SUMMARY Here, we report the results of a kinetic study on the hydrogen generation from the catalytic hydrolysis of sodium borohydride in a differential flow reactor. As catalyst platinum supported on carbon (Pt/C) was used in two forms: either as powder or coated on carbon cloth. For optimization of the system several parameters such as sodium hydroxide concentration, sodium borohydride concentration and the flow rate of the feed solution were varied. It was found that the H2 generation rate increases with an increase in NaBH4 concentration whereas it shows a slight decrease with variation in NaOH concentration. As an important parameter, an increase in the flow rate of feed solution enhances the hydrogen generation rate. This is an important result as it provides an easy control of reaction or hydrogen generation on demand. Copyright © 2013 John Wiley & Sons, Ltd.

Simulation of a stand-alone residential PEMFC power system with sodium borohydride as hydrogen source

Catalytic hydrolysis of sodium borohydride (NaBH4) has been investigated as a method to generate hydrogen for fuel cell applications. The high purity of the generated hydrogen makes this process a potential source of hydrogen for polymer electrolyte membrane fuel cells (PEMFCs). In this paper, a PEMFC power system employing a NaBH4 hydrogen generator is designed to supply continuous power to residential power applications as stand-alone loads and simulated using Matlab/Simulink software package. The overall system is sized to meet a real end-use load, representative of standard European domestic medium electric energy consumption, over a 1-week period. Supervisory control strategies are proposed to manage the hydrogen generation and storage, and the power flow. Simulation results show that the proposed supervisory control strategies are effective and the NaBH4–PEMFC power system is a technologically feasible solution for stand-alone residential applications.

Hydrogen generation from catalytic hydrolysis of sodium borohydride by a novel Co(II)–Cu(II) based complex catalyst

In the present work, Co(II)–Cu(II) supported salicylaldimine derivatives complex catalysts and their mixtures are tested for hydrogen generation from the hydrolysis reaction of sodium borohydride (NaBH4). The hydrolysis of NaBH4 with Co(II)–Cu(II) supported complex catalysts is investigated depending on the Co(II)–Cu(II) ratio, NaBH4 concentration, NaOH concentration, temperature and catalyst amount. The results suggested that the optimal mixture percentage of Co(II)–Cu(II) catalyst is 40:60. The obtained complex catalysts are characterized by XRD, FT-IR and SEM techniques and evaluated for their activity for the hydrogen generation from the hydrolysis reaction of NaBH4.

Novel homogeneous catalyst comprising ruthenium and trimethylphosphite for the hydrolysis of sodium borohydride

Homogeneous catalytic hydrolysis of sodium borohydride starting with Ru(acac) 3 (acac = acetylacetonate) and P(OMe) 3 was followed by monitoring the hydrogen evolution and the UV–vis electronic absorption spectra which shows the conversion of all ruthenium(III) to a ruthenium(II) species, most likely acting as catalyst. This active catalyst is alive only under reducing conditions and converted mainly to Ru(acac) 3 along with other minor complexes when the catalytic reaction is over. A ruthenium(II) complex was isolated from the reaction solution after the complete catalytic hydrolysis of sodium borohydride and characterized to be [Ru{P(OMe) 3} 4H 2] by single crystal XRD, MS, UV–vis, FTIR, 1H, 13C and 31P NMR spectroscopy. [Ru{P(OMe) 3} 4H 2] complex crystallizes in the triclinic space group P-1 with a = 10.066(2) Å, b = 19.108(3) Å, c = 20.938(4) Å, α = 78.839(14)°, β = 87.308(16)° and γ = 79.506(14)°. This ruthenium(II) complex was found not to be the active catalyst in the hydrolysis of sodium borohydride, rather one of its conversion products after catalysis. Although the active catalyst could not be isolated from the reaction solution, it could be stabilized by adding chelating 2,2′-bipyridine into the solution during the catalysis. Thus, a stabilized form of the active catalyst, [Ru(acac)(bipy){P(OMe) 3}H], could be isolated and characterized by MS, UV–vis, FTIR, 1H, 13C and 31P NMR spectroscopy. [Ru(acac)(bipy){P(OMe) 3}H] is expectedly not as active as the ruthenium(II) species formed in situ during the catalysis. Taking all the results together reveals that the active catalyst is a ruthenium(II) complex, either [Ru(acac){P(OMe) 3} 3H] or most likely its dissociation product, [Ru(acac){P(OMe) 3} 2H]. Control experiments showed that 2,2′-bipyridine can replace only the trimethylphosphite ligands but not the acetylacetonato ligand in the ruthenium(II) complex.

Stability, durability, and reusability studies on transition metal-doped Co–B alloy catalysts for hydrogen production

In addition to high catalytic efficiency the catalyst must also comprise important features like high stability in severe conditions, ability to be recycled several times and should have high tolerance against deactivation. This work is oriented specifically to study these properties of already developed efficient transition-metal doped Co–B alloy catalyst. Various transition metals, namely Ni, Fe, Cu, Cr, Mo, and W, were singly added as dopants in Co–B catalyst by chemical reduction of the corresponding metal salts. These alloy catalysts were calcinated, in Ar atmosphere, at 673, 773, and 873 K in order to investigate the stability of the powders at elevated temperatures. The catalytic performances of these treated catalyst powders were tested for H 2 generation by catalytic hydrolysis of sodium borohydride (NaBH 4). The alloy powders were exposed to ambient condition for several days to test their tolerance against deactivation and self life. After separation from the reaction course and after rinsing, the catalyst powders were tested for several cycles to evaluate the reusability property. The observed changes in the catalytic activity were discussed on the basis of structural and morphological variations. The Co–B catalyst, when doped with Ni, Mo, and W metals showed high stability and resistance against deterioration, as function of both time and use, as compared to Cr- and Fe-doped alloy powders. A much lower performance with respect to calcination temperature, holding time, and number of cycles was established for Cu doped Co–B catalyst powder.

Effect of stabilizer type on the activity and stability of water-dispersible cobalt(0) nanocluster catalysts in hydrogen generation from the hydrolysis of sodium borohydride

Hydrogen phosphate (HPO4 2−) or poly(acrylic acid) (PAA) stabilized cobalt(0) nanoclusters were in situ generated from the reduction of cobalt(II) chloride during the catalytic hydrolysis of sodium borohydride (NaBH4) in the presence of stabilizers, HPO4 2− or PAA. Cobalt(0) nanoclusters stabilized by HPO4 2− or PAA were characterized by using UV–Visible spectroscopy, TEM, XPS and FT-IR techniques. They were employed as catalysts in the hydrolysis of NaBH4 to examine the effect of stabilizer type on their catalytic activity and stability. Detailed reaction kinetics of the hydrolysis of NaBH4 in the presence of both catalysts was studied depending on catalyst concentration, substrate concentration and temperature. PAA stabilized cobalt(0) nanoclusters provided higher total turnover number (TTON = 6,600) than that of HPO4 2− stabilized cobalt(0) nanoclusters (1,285 turnovers). However, the HPO4 2− stabilized cobalt(0) nanoclusters provided a lower activation energy (E a = 53 ± 2 kJ mol−1) than the PAA stabilized cobalt(0) nanoclusters (E a = 58 ± 2 kJ mol−1) for the hydrolysis of NaBH4. The use of two types of stabilizers in the preparation of the same metal(0) nanoclusters following the same methodology enables us to compare the electrostatic and steric stabilization in terms of the catalytic activity and stability of metal(0) nanoclusters.

Development of a compact hydrogen generator from sodium borohydride

Chemical hydrides can be a simple and safe hydrogen vector for polymer fuel cells. In particular the catalytic hydrolysis of sodium borohydride (NaBH 4) is here envisaged to produce on-demand hydrogen to be supplied to a small solid polymer fuel cell in a portable energy generator. A compact hydrogen generator is designed around a tubular catalytic reactor, whose catalytic powder is held in place by magnetic field. The gas is generated by the exothermic hydrolysis reaction of an aqueous sodium borohydride solution in contact with no-noble catalyst particles inside the reactor. The reaction produces wet hydrogen and borate, which is soluble in water and not harmful to the environment. When hydrogen demand stops, the reactor is emptied and the hydrolysis reaction ceases. A generator was then tested showing a smooth operation and a reasonably good performance. Correct choice of operating conditions and start-up procedures are requested to have a hydrogen production adequate to the fuel cell needs.

Mechanochemical Synthesis of Sodium Borohydride by Recycling Sodium Metaborate

Hydrogen can be easily produced from the catalytic hydrolysis of sodium borohydride (NaBH4), with sodium metaborate (NaBO2) being the co-product. If NaBO2 can be economically recycled in the process, NaBH4 could be considered as a promising hydrogen carrier in fuel cells because of its high hydrogen content. In this paper, we report our investigation into the synthesis of NaBH4 from NaBO2 via ball milling. The starting materials for the synthesis were NaBO2 and magnesium hydride (MgH2). After ball milling at ambient temperature in inert gas, NaBH4 and magnesium oxide (MgO) were produced. The synthesized NaBH4 was extracted from the admixture by isopropylamine. Our results indicated that the yield of NaBH4 from this process was 71 wt % when the MgH2/NaBO2 mole ratio, ball/powder ratio (BPR), inert gas (argon) pressure, and milling time were 2.07:1, 50:1, 200 kPa, and 2 h, respectively. The mole ratio of the reactants (MgH2 and NaBO2), ball-milling time, BPR, and milling atmosphere were found to have significant influence over NaBH4 synthesis. We present the results and discuss the effects of these key parameters in this paper.

Synthesis and characterization of poly( N-vinyl-2-pyrrolidone)-stabilized water-soluble nickel(0) nanoclusters as catalyst for hydrogen generation from the hydrolysis of sodium borohydride

Water-soluble PVP-stabilized nickel(0) nanoclusters in particle size of 3.6 ± 1.6 nm were synthesized by using a modified version of alcohol reduction method and characterized by TEM, XPS and FT-IR. PVP polymer is coordinated to the nanoclusters surface through some of the carbonyl groups as concluded from a comparative FT-IR spectral study. The PVP-stabilized nickel(0) nanoclusters are very stable in solution and yet highly active catalyst providing 8700 turnovers of hydrogen gas generation from the hydrolysis of sodium borohydride over 27 h before deactivation. They can be isolated as stable solid material, which are redispersible in water and show still the same catalytic activity after redispersion. A kinetic study shows that the catalytic hydrolysis of sodium borohydride is first order with respect to nickel concentration and zero order with respect to substrate concentration. The activation energy of the hydrolysis of sodium borohydride catalyzed by PVP-stabilized nickel(0) nanoclusters was determined to be E a = 48 ± 2 kJ mol −1.

Carbon-supported cobalt catalyst for hydrogen generation from alkaline sodium borohydride solution

Low cost transition metal catalysts with high performance are attractive for the development of on-board hydrogen generation systems by catalytic hydrolysis of sodium borohydride (NaBH 4) in fuel cell fields. In this study, hydrogen production from alkaline NaBH 4 via hydrolysis process over carbon-supported cobalt catalysts was studied. The catalytic activity of the supported cobalt catalyst was found to be highly dependent on the calcination temperatures. The hydrogen generation rate increases with calcination temperatures in the range of 200–400 °C, but a high calcination temperature above 500 °C led to markedly decreased activity. X-ray diffraction patterns reveal that the catalysts experience phase transition from amorphous Co–B to crystalline cobalt hydroxide with increase in calcination temperatures. The reaction performance is also dependent on the concentration of NaBH 4, and the hydrogen generation rate increases for lower NaBH 4 concentrations and decreases after reaching a maximum at 10 wt.% of NaBH 4.

Catalytic hydrolysis of sodium borohydride in an integrated reactor for hydrogen generation

Chemical hydrides, such as sodium borohydride ( NaBH 4 ) , offer promising gravimetric and volumetric hydrogen storage densities. The overall system energy density depends on the reactor performance. In this study, a novel intergrated reactor design in which catalyst bed is integrated with a heat exchanger for autothermal operation showed significant improvements in reactor performance. Over 200% enhancement in reactor throughput was achieved with the integrated reactor at 99% fuel conversion with constant reaction temperature profiles over a wide range of fuel flow rates. Impacts of improved performance on system operation and overall energy density of chemical hydride based hydrogen storage system were also discussed.

Catalytic hydrolysis of sodium borohydride by a novel nickel–cobalt–boride catalyst

With the aim of designing an efficient hydrogen generator for portable fuel cell applications nickel–cobalt–boride (Ni–Co–B) catalysts were prepared by a chemical reduction method and their catalytic hydrolysis reaction with alkaline NaBH 4 solution was studied. The performance of the catalysts prepared from NaBH 4 solution with NaOH, and without NaOH show different hydrogen generation kinetics. The rate of hydrogen generation was measured using Ni–Co–B catalyst as a function of the concentrations of NaOH and NaBH 4, as well as the reaction temperature, in the hydrolysis of alkaline NaBH 4 solution. The hydrogen generation rate increases for lower NaOH concentrations in the alkaline NaBH 4 solution and decreases after reaching a maximum at 15 wt.% of NaOH. The hydrogen generation rate is found to be constant with respect to the concentration of NaBH 4 in the alkaline NaBH 4 solution. The activation energy for hydrogen generation is found to be 62 kJ mol −1, which is comparable with that of hydrogen generation by a ruthenium catalyst.

Thin films of Co–B prepared by pulsed laser deposition as efficient catalysts in hydrogen producing reactions

Abstract Hydrogen generation by catalytic hydrolysis of sodium borohydride (NaBH 4 ) is studied by using Co–B-based thin film catalyst synthesized by pulsed laser deposition (PLD) technique. Co–B nanoparticles, produced in the catalyst film after the laser ablation process, act as active centers producing significantly higher H 2 generation rate than Co–B bulk powder. Surface morphology was studied by using scanning electron microscopy and compositional analysis was established by using X-photoelectron and infrared spectroscopies. Films were deposited at different PLD set-up parameters in order to understand the possible role of size and density of the nanoparticles in the catalytic process. Cobalt has been found here to act as an efficient catalyst only when alloyed with boron which partially prevents cobalt oxidation. In particular we report that when used as suitable thin films, Co–B produces H 2 with a maximum generation rate of about 3300 ml/min per gram of catalyst.

06/02687 Catalytic hydrolysis of sodium borohydride in an auto-thermal fixed-bed reactorZhang, Q. et al. International Journal of Hydrogen Energy, 2006, 31, (7), 961–965

06/02687 Catalytic hydrolysis of sodium borohydride in an auto-thermal fixed-bed reactorZhang, Q. et al. International Journal of Hydrogen Energy, 2006, 31, (7), 961–965

06/00049 Hydrogen generation from catalytic hydrolysis ofsodium borohydride for proton exchange membrane fuel cells: Wu, C. et al. Catalysis Today, 2004, 93–95, (1), 477–483

06/00049 Hydrogen generation from catalytic hydrolysis ofsodium borohydride for proton exchange membrane fuel cells: Wu, C. et al. Catalysis Today, 2004, 93–95, (1), 477–483

Catalytic hydrolysis of sodium borohydride in an auto-thermal fixed-bed reactor

Catalytic hydrolysis of sodium borohydride is a promising technology for hydrogen storage. In this study, we report the performance of Millennium Cell Hydrogen on Demand TM ( HOD TM ) hydrogen storage system using a supported catalyst. Dynamic reactor startup and response characteristics were measured using a fixed-bed catalyst reactor at various hydrogen demand conditions. The catalyst reactor was operated without need of fuel preheating. Catalyst durability of more than 700 h was demonstrated with a sodium borohydride conversion over 95% at a liquid feed hourly space velocity (LHSV) of about 15 h - 1 and under a system pressure of 483 kPa.