Reusable Catalyst For Hydrogen Generation Research Articles

Hydrolytic dehydrogenation of ammonia borane catalyzed by poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets supported Ag0.3Co0.7 nanoparticles

Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets (PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7 nanoparticles in order to obtain an excellent catalyst for ammonia borane (AB) hydrolysis. During the synthetic processes, GO could easily assembled with PAMAM by the electrostatic and hydrogen-bonding interactions. Structural characterization revealed that Ag0.3Co0.7 bimetallic nanoparticles with uniform size distribution of 5nm are well dispersed on PAMAM/rGO composite architecture. Ag0.3Co0.7@PAMAM/rGO was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value (TOF) of 19.79 molH2min–1molM–1 at 25.0±0.1°C and retained 75.4% of their initial activity with a complete release of hydrogen in five runs. The relatively high TOF value and low apparent activation energy (34.21kJmol–1) make these Ag0.3Co0.7@PAMAM/rGO NPs as a high-efficient catalyst for catalytic dehydrogenation of AB facilitating the development of practically applicable energy storage materials.

Nanozirconia supported ruthenium(0) nanoparticles: Highly active and reusable catalyst in hydrolytic dehydrogenation of ammonia borane

Nanozirconia supported ruthenium(0) nanoparticles (Ru0/ZrO2) were prepared by impregnation of ruthenium(III) cations on the surface of zirconia followed by their reduction with sodium borohydride at room temperature. Ru0/ZrO2 was isolated from the reaction solution by centrifugation and characterized by ICP-OES, XRD, TEM, SEM−EDS and XPS techniques. All the results reveal that ruthenium(0) nanoparticles were successfully supported on zirconia and the resulting Ru0/ZrO2 is a highly active and reusable catalyst for hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value of 173 min−1 at 25 °C. The reusability and catalytic lifetime tests reveal that Ru0/ZrO2 is still active in the subsequent runs of hydrolysis of ammonia borane preserving 67% of the initial catalytic activity even after the fifth run and Ru0/ZrO2 provides 72,500 turnovers (mol H2/mol Ru) before deactivation at 25 °C. Our report also includes the results of kinetic studies depending on the catalyst concentration and temperature to determine the activation energy (Ea = 58 ± 2 kJ/mol) for hydrolytic dehydrogenation of AB.

Pt coated Co nanoparticles supported on N-doped mesoporous carbon as highly efficient, magnetically recyclable and reusable catalyst for hydrogen generation from ammonia borane

Ammonia borane (NH3BH3, AB) is considered as an excellent chemical material for the hydrogen storage attribute to its high hydrogen storage capacity. However, developing highly efficient catalysts for continuous hydrogen generation from AB is still a challenge for the future fuel cell applications. Initially, a facile one-pot carbonization method was used for fabrication cobalt nanoparticles (Co NPs) doped fluffy N-doped mesoporous carbon (Co/mCN). Further, the Pt@Co/mCN nanocatalyst was prepared through a facile spontaneous displacement reaction by using the Co/mCN material and H2PtCl6 as the starting materials. Here, the metallic Pt only covered on the surface of the Co NPs in the view of Pt saving. The Pt@Co/mCN nanocatalyst was used in the catalytic hydrogen generation from AB and showed excellent catalytic activity and reusability. The superior catalytic activity of the Pt@Co/mCN nanocatalyst is probably due to the isolated Pt atoms on the surface of the Co NPs and the highly dispersed Pt@Co NPs on the surface of the fluffy mCN support.

Ruthenium nanoparticles immobilized on surfactant-directed polypyrrole as an effective and reusable catalyst for hydrogen generation

An effective catalyst with high activity and stability is required to produce hydrogen from the hydrolysis of sodium borohydride (NaBH4) for the portable fuel cell applications. In this study, the synthesis of highly effective, stable and reusable polypyrrole (PPy) supported ruthenium nanoparticles (NPs) is presented. PPy powders with porous structure were prepared by the chemical oxidative polymerization, followed by the deposition of Ru NPs using the wet impregnation—reduction method. Due to the synergistic effect of Ru NPs with PPy, the as-synthesized catalyst exerts good catalytic activity, with the hydrogen release rate of 22.74 ± 0.84 L min−1 g Ru −1 and activation energy of 39.08 ± 1.69 kJ mol−1, which is lower than most of the reported activation energy values. This novel Ru/PPy catalyst is a promising candidate for small portable hydrogen generators by NaBH4 hydrolysis. Structural, morphological and textural properties of the catalysts were investigated by analytical techniques. Moreover, the effects of reaction temperature, NaOH and NaBH4 concentrations on catalytic activity were also investigated.

Palladium(0) nanoparticles supported on polydopamine coated CoFe2O4 as highly active, magnetically isolable and reusable catalyst for hydrogen generation from the hydrolysis of ammonia borane

Palladium(0) nanoparticles supported on cobalt ferrite (Pd0/CoFe2O4) are found to be highly active catalyst, providing an unprecedented catalytic activity with a turnover frequency of 290min−1 in hydrogen generation from the hydrolysis of ammonia borane at room temperature. However, the initial catalytic activity of Pd0/CoFe2O4 catalyst is not preserved after the reuse of the catalyst in hydrolytic dehydrogenation of ammonia borane. The stability of the catalyst is improved by using the polydopamine (PDA) coated cobalt ferrite as support instead of bare cobalt ferrite. PDA coating of CoFe2O4 nanopowders was achieved by pH-induced self-polymerization of dopamine hydrochloride at room temperature and the thickness of PDA was optimized by changing the amount of dopamine hydrochloride. Palladium(0) nanoparticles supported on PDA coated cobalt ferrite (Pd0/PDA–CoFe2O4) were prepared by two step impregnation-reduction process and characterized by a combination of advanced analytical techniques. The results reveal that palladium nanoparticles with an average size of 1.4±0.3nm are well dispersed on polydopamine layer with a thickness of 8.6±1.0nm on the surface of cobalt ferrite nanopowders. Pd0/PDA–CoFe2O4 with a palladium loading of 1.08wt% was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency of 175min−1 at 25.0±0.1°C. Magnetically isolable Pd0/PDA–CoFe2O4 catalyst preserves its initial catalytic activity even after the tenth use providing the release of 3 equivalent H2 per mole of ammonia borane.

Nanoceria supported cobalt(0) nanoparticles: a magnetically separable and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane

Co0/CeO2 is a magnetically separable and highly reusable catalyst in the hydrolysis of ammonia borane.

Polyacrylonitrile Fibers Anchored Cobalt/Graphene Sheet Nanocomposite: A Low-Cost, High-Performance and Reusable Catalyst for Hydrogen Generation.

Cobalt and its composites are known to be active and inexpensive catalysts in sodium borohydride (NaBH4) hydrolysis to generate clean and renewable hydrogen energy. A novel fiber catalyst, cobalt/graphene sheet nanocomposite anchored on polyacrylonitrile fibers (Co/GRs-PANFs), which can be easily recycled and used in any reactor with different shapes, were synthesized by anchoring cobalt/graphene (Co/GRs) on polyacrylonitrile fibers coated with graphene (GRs-PANFs) at low temperature. The unique structure design effectively prevents the inter-sheet restacking of Co/GRs and fully exploits the large surface area of novel hybrid material for generate hydrogen. And the extra electron transfer path supplied by GRs on the surface of GRs-PANFs can also enhance their catalysis performances. The catalytic activity of the catalyst was investigated by the hydrolysis of NaBH4 in aqueous solution with GRs-PANFs. GRs powders and Co powders were used as control groups. It was found that both GRs and fiber contributed to the hydrogen generation rate of Co/GRs-PANFs (3222 mL x min(-1) x g(-1)), which is much higher than that of cobalt powders (915 mL x min(-1) x g(-1)) and Co/GRs (995 mL x min(-1) x g(-1)). The improved hydrogen generation rate, low cost and uncomplicated recycling make the Co/GRs-PANFs promising candidate as catalysts for hydrogen generation.

Palladium(0) nanoparticles supported on ceria: Highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane

Palladium(0) nanoparticles supported on nanoceria (Pd0/CeO2) were prepared by the impregnation of palladium(II) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. Pd0/CeO2 were isolated from the reaction solution by centrifugation and characterized by ICP-OES, XRD, TEM, SEM-EDS and XPS techniques. All the results reveal that palladium(0) nanoparticles were uniformly dispersed on ceria and the resulting Pd0/CeO2 are highly active and reusable catalysts in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value of 29 min−1 at 25.0 ± 0.1 °C. The catalytic activity of Pd0/CeO2 in hydrogen generation from the hydrolysis of ammonia borane is higher compared to that of other palladium based catalysts such as Pd0/ZrO2, Pd0/SiO2, Pd0/Al2O3, Pd0/TiO2 under the same conditions. The catalytic activity of Pd0/CeO2 samples with various palladium loading in the range of 1.0–5.0% wt Pd was tested in hydrogen generation from the hydrolysis of ammonia borane at 25.0 ± 0.1 °C. The highest catalytic activity was achieved by using 1.18% wt palladium loaded ceria. The reusability tests reveal that Pd0/CeO2 are still active in the subsequent runs of hydrolysis of ammonia borane preserving 47% of the initial catalytic activity even after the fifth run of hydrolysis. Our report also includes the results of kinetic study of the catalytic hydrolysis of ammonia borane depending on the temperature and catalyst concentration.

Palladium(0) nanoparticles supported on polydopamine coated Fe3O4 as magnetically isolable, highly active and reusable catalysts for hydrolytic dehydrogenation of ammonia borane

Palladium(0) nanoparticles supported on polydopamine coated magnetic ferrite nanopowders are highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency of 14.5 min−1 at 25.0 ± 0.1 °C.

Ruthenium(0) nanoparticles supported on magnetic silica coated cobalt ferrite: Reusable catalyst in hydrogen generation from the hydrolysis of ammonia-borane

Ruthenium(0) nanoparticles supported on magnetic silica-coated cobalt ferrite (Ru(0)/SiO2-CoFe2O4) were in situ generated from the reduction of Ru3+/SiO2-CoFe2O4 during the catalytic hydrolysis of ammonia-borane (AB). Ruthenium(III) ions were impregnated on SiO2-CoFe2O4 from the aqueous solution of ruthenium(III) chloride and then reduced by AB at room temperature yielding Ru(0)/SiO2-CoFe2O4 which were isolated from the reaction solution by using a permanent magnet and characterized by ICP-OES, XRD, TEM, TEM-EDX and XPS techniques. The resulting magnetically isolable Ru(0)/SiO2-CoFe2O4 were found to be highly reusable catalyst in hydrolysis of AB retaining 94% of their initial catalytic activity even after tenth run. Ru(0)/SiO2-CoFe2O4 provide the highest catalytic activity after the tenth use in hydrolysis of AB as compared to the other ruthenium catalysts. The work reported here also includes the formation kinetics of ruthenium(0) nanoparticles. The evaluation of rate constants for the nucleation and autocatalytic surface growth of ruthenium(0) nanoparticles at various temperatures provides the estimation of activation energy for both reactions; Ea=116±7kJ/mol for the nucleation and Ea=51±2kJ/mol for the autocatalytic surface growth of ruthenium(0) nanoparticles. The report also includes the activation energy of the catalytic hydrogen generation from the hydrolysis of AB (Ea=45±2kJ/mol) determined from the evaluation of temperature dependent kinetic data and the effect of catalyst concentration on the rate of hydrolysis of AB.

Ruthenium(0) nanoparticles supported on nanotitania as highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane

Ruthenium(0) nanoparticles supported on the surface of titania nanospheres (Ru(0)/TiO2) were in situ generated from the reduction of ruthenium(III) ions impregnated on nanotitania during the hydrolysis of ammonia borane. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The results reveal that highly dispersed ruthenium(0) nanoparticles of size in the range 1.5–3.3 nm were formed on the surface of titania nanospheres. Ru(0)/TiO2 show high catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value up to 241 min−1 at 25.0 ± 0.1 °C. They provide unprecedented catalytic lifetime measured by total turnover number (TTO = 71,500) in hydrogen generation from the hydrolysis of ammonia borane at 25.0 ± 0.1 °C. The report also includes the results of kinetic study on the catalytic hydrolysis of ammonia borane depending on the temperature to determine the activation energy of the reaction (Ea = 70 ± 2 kJ/mol) and the catalyst concentration to establish the rate law of the reaction.

Cobalt–nickel–phosphorus supported on Pd-activated TiO 2 (Co–Ni–P/Pd-TiO 2) as cost-effective and reusable catalyst for hydrogen generation from hydrolysis of alkaline sodium borohydride solution

Catalytically active, low-cost, and reusable transition metal catalysts are desired to develop on-demand hydrogen generation system for practical onboard applications. Electrolessly deposited Pd-activated TiO 2-supported Co–Ni–P ternary alloy catalyst (Co–Ni–P/Pd-TiO 2) is employed as catalyst in the hydrolysis of alkaline sodium borohydride solution. The catalyst is found to be isolable, redispersible, and reusable in the hydrolysis of alkaline NaBH 4. 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 = 57.0 kJ/mol) and effects of the amount of catalyst, amount of substrate, and temperature on the rate for the catalytic hydrolysis of NaBH 4. Maximum H 2 generation rate of ∼460 mL H 2 min −1 (g catalyst) −1 and ∼3780 mL H 2 min −1 (g catalyst) −1 was measured by the hydrolysis of NaBH 4 at 25 °C and 55 °C, respectively.

Hydroxyapatite-supported palladium(0) nanoclusters as effective and reusable catalyst for hydrogen generation from the hydrolysis of ammonia-borane

Herein we report the preparation, characterization and catalytic use of hydroxyapatite-supported palladium(0) nanoclusters in the hydrolysis of ammonia-borane. Palladium(0) nanoclusters were formed in situ from the reduction of palladium(II) ion exchanged hydroxyapatite during the hydrolysis of ammonia-borane and supported on hydroxyapatite. The hydroxyapatite-supported palladium(0) nanoclusters are stable enough to be isolated as solid materials and characterized by using a combination of advanced analytical techniques. They are isolable, redispersible and reusable as an active catalyst in the hydrolysis of ammonia-borane even at low concentration and temperature. They provide a maximum hydrogen generation rate of ∼1425 mL H 2 min −1 (g Pd) −1 and 12300 turnovers in the hydrolysis of ammonia-borane at 25 ± 0.1 °C before deactivation. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy ( E a = 54.8 ± 2.2 kJ/mol) and the effect of catalyst concentration on the rate for the catalytic hydrolysis of ammonia-borane.

Polymer-immobilized palladium supported on TiO 2 (Pd–PVB–TiO 2) as highly active and reusable catalyst for hydrogen generation from the hydrolysis of unstirred ammonia–borane solution

Herein we report the preparation, characterization and the catalytic use of the polymer-immobilized palladium catalyst supported on TiO 2 (Pd–PVB–TiO 2) in the hydrolysis of unstirred ammonia–borane solution. The polymer-immobilized palladium catalyst is stable enough to be isolated as solid materials and characterized by XRD, SEM, and EDX. The immobilized palladium catalyst supported on TiO 2 is found highly active, isolable, and reusable in the hydrolysis of unstirred ammonia–borane even at low concentrations and temperature. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy ( E a = 55.9 kJ/mol) and the effects of catalyst and substrate concentration on the rate for the hydrolysis of unstirred ammonia–borane solution. Maximum H 2 generation rate of ∼642 mL H 2 min −1 (g Pd) −1 and ∼4367 mL H 2 min −1 (g Pd) −1 was measured by the hydrolysis of AB at 25 °C and 55 ± 0.5 °C, respectively.

Zeolite confined palladium(0) nanoclusters as effective and reusable catalyst for hydrogen generation from the hydrolysis of ammonia-borane

Zeolite confined palladium(0) nanoclusters were prepared by a two step procedure: incorporation of Pd 2+ ions into the zeolite-Y by ion-exchange followed by the reduction of Pd 2+ ions in the supercages of zeolite-Y with sodium borohydride at room temperature. Zeolite confined palladium(0) nanoclusters are stable enough to be isolated as solid materials and characterized by ICP-OES, XRD, HRTEM, SEM, X-ray photoelectron spectroscopy and N 2 adsorption technique. These nanoclusters are isolable, redispersible and reusable as an active catalyst in the hydrolysis of ammonia-borane solution. Zeolite confined palladium(0) nanoclusters provide 15,600 turnovers in hydrogen generation from the hydrolysis of ammonia-borane at 25.0 ± 0.1 °C.

Zeolite confined copper(0) nanoclusters as cost-effective and reusable catalyst in hydrogen generation from the hydrolysis of ammonia-borane

Herein we report the development of a cost-effective nanocluster catalyst for the hydrolytic dehydrogenation of ammonia-borane which is considered to be one among the new hydrogen storage materials. Zeolite confined copper(0) nanoclusters were prepared by the ion-exchange of Cu 2+ ions with the extra framework Na + ions in zeolite-Y followed by reduction of the Cu 2+ ions within the cavities of zeolite with sodium borohydride in aqueous solution and characterized by HR-TEM, XRD, XPS, SEM, EDX, ICP-OES, Raman spectroscopy and N 2 adsorption–desorption technique. Zeolite confined copper(0) nanoclusters are found to be active catalysts in the hydrolysis of ammonia-borane even at low temperatures (≤15 °C) and stable enough for being isolated as solid materials. They provide 1300 turnovers in hydrogen generation from the hydrolysis of ammonia–borane at room temperature. The average value of turnover frequency is 46.5 h −1 for the same reaction. More importantly, zeolite confined copper(0) nanoclusters were found to be isolable, bottleable and reusable catalysts in the hydrolytic dehydrogenation of ammonia-borane; even at fifth run the complete release of hydrogen from the hydrolysis of ammonia-borane at room temperature is achieved. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy and the effect of catalyst concentration on the rate for the catalytic hydrolysis of ammonia–borane.

Intrazeolite cobalt(0) nanoclusters as low-cost and reusable catalyst for hydrogen generation from the hydrolysis of sodium borohydride

Intrazeolite cobalt(0) nanoclusters were prepared by ion-exchange of Co2+ ions with the extraframework Na+ ions in the zeolite-Y followed by the reduction of Co2+ ions in the supercages of zeolite-Y with sodium borohydride at room temperature. The intrazeolite cobalt(0) nanoclusters were isolated as solid materials and characterized by ICP-OES, XRD, HRTEM, SEM, XPS, Raman spectroscopy and N2 adsorption technique. The catalytic activities of intrazeolite cobalt(0) nanoclusters in the hydrolysis reaction of sodium borohydride solution in the absence or presence of added base were studied. They are found to be more active in basic solution than in aqueous solution without added base. They provide 36,000 total turnovers and a turnover frequency up to 880molH2(molCo)−1h−1 in the hydrolysis of basic sodium borohydride solution at 25.0±0.1°C. The improved hydrogen generation rate, hydrogen generation efficiency, lower activation energy and the low cost make the intrazeolite cobalt(0) nanoclusters promising candidate as catalyst for the hydrogen generation from basic sodium borohydride solution.