Effect of phosphoric acid and acetic acid addition on the hydrogen evolution using Ni based catalyst prepared in ethanol,methanol, and water solvents

Ni-based catalysts were synthesized in water, methanol and ethanol solvents by chemical reduction with sodium borohydride (NaBH₄). The obtained catalyst for the first time was used to catalyze the NaBH₄ hydrolysis reaction with phosphoric acid and acetic acid including different concentrations. The maximum hydrogen production rates obtained in the hydrolysis reaction including 0.5 M phosphoric acid and 0.1 M acetic acid of the Ni-based catalyst prepared in ethanol solvent were 5214 and 3650 ml g^?1 min^?1, respectively.     

Semi-methanolysis reaction of potassium borohydride with phosphoric acid for effective hydrogen production

The methanol and water solvents were used for the production of hydrogen from potassium borohydride. In addition, phosphoric acid was selected as the green catalyst so that this semi-methanolysis reaction would be more effective for the first time. The semi-methanolysis of potassium borohydride is investigated depend on potassium borohydride, phosphoric acid concentrations and temperatures. The maximum normalized hydrogen production rate obtained from this semi-methanolysis reaction with 1 M phosphoric acid as a catalyst was 5779 ml min ^?1 g^?1. In addition, this semi-methanolysis reaction was completed in 5 s. Kinetic studies have been carried out with the power law kinetic model. The activation energy obtained for this semi-methanolysis reaction is 1.45 kJ mol^?1.     

Controllable hydrogen production from NaBH4 hydrolysis promoted by acetic acid

Numerous catalysts have been widely investigated for accelerating hydrogen production from NaBH₄ hydrolysis. However, these catalysts are usually complicated in structures, costly in fabrication, and hazardous for environment. In this work, cheap and environment-friendly acetic acid, CH₃COOH, is employed to promote NaBH₄ hydrolysis to produce hydrogen in a considerable rate. The experimental results demonstrate that the addition of suitable amount of CH₃COOH into NaBH₄ solutions stabilized with NaOH could dramatically accelerate the hydrolysis reaction. Additionally, the start/stop of NaBH₄ hydrolysis could be controlled by adding acid or base into the solution to realize “go-as-you-please” on-site hydrogen production.     

Apricot Kernel shell waste treated with phosphoric acid used as a green,metal-free catalyst for hydrogen generation from hydrolysis of sodium borohydride

In this study, grinded apricot kernel shell (GAKS) biobased waste was used for the first time as a cost-effective, efficient, green and metal-free catalyst for hydrogen generation from the hydrolysis reaction of sodium borohydride (NaBH₄). For the hydrogen production by NaBH₄ hydrolysis reaction, GAKS was treated with various acids (HCl, HNO₃, CH₃COOH, H₃PO₄), salt (ZnCl₂) and base (KOH). As a result, the phosphoric acid (H₃PO₄) demonstrated better catalytic activity than other chemical agents. The hydrolysis of NaBH₄ with the GAKS-catalyst (GAKS_cat) was studied depending on different parameters such as acid concentration, furnace burning temperature and time, catalyst amount, NaBH₄ concentration and hydrolysis reaction temperature. The obtained GAKS_cat was characterized by ICP-MS, elemental analysis, TGA, XRD, FT-IR, Boehm, TEM and SEM analyses and was evaluated for its catalytic activity in the hydrogen production from the hydrolysis reaction of NaBH₄. According to the results, the optimal H₃PO₄ percentage was found as 15%. The maximum hydrogen generation rate from the hydrolysis of NaBH₄ with the GAKS_cat was calculated as 20,199 mL min⁻¹ g_cat⁻¹. As a result, it can be said that GAKS treated with 15% H₃PO₄ as a catalyst for hydrogen production is an effective alternative due to its high hydrogen production rate.     

Preparation of hollow poly(vinylidene fluoride) capsules containing nickel catalyst for hydrogen storage and production

Hollow polymer capsules offer an approach for storage of hydrogen. Thus, in this paper, hollow poly(vinylidene fluoride) capsules were prepared by phase inversion of a polyvinylidene fluoride solution containing sodium borohydride that reacts with water to produce hydrogen during the phase separation. The effects of additives on the structure of the capsules were observed by scanning electronic microscopy and on the adsorption property were investigated by adsorbing sodium borohydride. The effects of the amount of capsules, concentration of sodium borohydride, and temperature on hydrogen production were studied via catalytic hydrolysis of sodium borohydride in aqueous solution. It was noticed that the capsules have good catalytic activity for hydrolysis of sodium borohydride with an activation energy of 49.3 kJ mol^?1. And the capsules can be used for adsorption of sodium borohydride in tetrahydrofuran before catalytic hydrolysis of sodium borohydride in water. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimisation of sepiolite clay with phosphoric acid treatment as support material for CoB catalyst and application to produce hydrogen from the NaBH4 hydrolysis

Herein, the CoB catalyst supported on the sepiolite clay treated with phosphoric acid was utilized to produce hydrogen from the NaBH₄ hydrolysis. In order to analyse the performance of the phosphoric acid treated sepiolite clay supported-CoB catalyst, the NaBH₄ concentration effect, phosphoric acid concentration effect, phosphoric acid impregnation time effect, CoB catalyst percentage effect, and temperature effect were studied. In addition, XRD, XPS, SEM, TEM, BET, and FTIR analysis were performed for characterization of Co–B catalyst supported on the acid-treated sepiolite. The completion time of this hydrolysis reaction with Co–B (20%) catalyst supported on the sepiolite treated by 5 M phosphoric acid was approximately 80 min, whereas the completion time of this hydrolysis reaction with acid-free sepiolite-supported Co–B (20%) catalyst was approximately 260 min. There is a five-fold increase in the maximum production rate. The maximum hydrogen production rates of this hydrolysis reaction at 30 and 60 °C were found as 1486 and 5025 ml min⁻¹g⁻¹_catalyst, respectively. Activation energy was found as 21.4 kJ/mol. This result indicates that the acid treatment on sepiolite is quite successful. The re-usability of NaBH₄ hydrolysis reaction by CoB catalyst supported on sepiolite treated phosphoric acid for successive five cycles of NaBH₄ at 30 °C was investigated.     

Metal-free catalyst fabrication by incorporating oxygen groups on the surface of the carbonaceous sample and efficient hydrogen production from NaBH4 methanolysis

In the present study, metal-free catalysts for efficient H₂ generation from NaBH₄ methanolysis was produced for the first time from apricot kernel shells with two-step activation. The first stage of the two-stage activation includes the production of activated carbon with the KOH agent (AKOH), and the second stage includes hydrothermally HNO₃ activation with oxygen doping (O doped AKOH + N). The hydrogen production rate (HGR) and the activation energy (Ea) of the reaction with the obtained metal-free catalyst (10 mg) were determined as 14,444 ml min^?1 g^?1 and 7.86 kJ mol^?1, respectively. The structural and physical-chemical properties of these catalysts were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), elemental CHNS analysis, FT-IR (Fourier transform infrared spectroscopy), and nitrogen adsorption analysis. Also, the reusability results of this metal-free catalyst for H₂ production are promising.     

A novel cost-effective catalyst from orange peel waste protonated with phosphoric acid for hydrogen generation from methanolysis of NaBH4

In this study, orange peel (OP), one of the organic wastes, was first used as a metal-free catalyst for the production of hydrogen from sodium boron hydride (NaBH₄). In order to prepare an orange peel catalyst (OP–H₃PO₄-Cat) with the best catalytic activity, experiments were carried out on pure orange peel with different acid types, different burning temperatures and different burning times. As a result of these experiments, it was determined that OP-H₃PO₄-Cat treated with 30% H₃PO₄ and burned at 400 °C for 45 min had the best catalytic activity. The OP-H₃PO₄-Cat material was characterised by several techniques such as FTIR, XRD and SEM. As a result, the hydrogen generation rates (HGR) at 30 °C and 60 °C in the methanolysis reaction of 2.5% NaBH₄ catalysed by OP-H₃PO₄-Cat were found as 45,244 and 61,892 mLmin^?1g.cat^?1, respectively. The activation energy of OP-H₃PO₄-Cat catalyst was calculated as 12.47 kJmol^-1.     

Fe doped-CoB catalysts with phosphoric acid-activated montmorillonite as support for efficient hydrogen production via NaBH4 hydrolysis

In this study, montmorillonite (MMT) clay was modified with different acids to be used as support material. The modified MMT clay was used to obtain hydrogen in the hydrolysis reactions of NaBH₄ (NaBH₄-HR) as a support material for the Co–B and Co–Fe–B catalyst. During the activation of MMT clay, the effects of different acids, phosphoric acid (H₃PO₄) concentration, and impregnation time with H₃PO₄ were investigated. During the hydrogen generation from the NaBH₄-HR, effects of Co loading, Fe loading, NaBH₄ concentration, temperature and, catalyst durability were investigated. The maximum HGRs for MMT-H₃PO₄–CoB and MMT-H₃PO₄–Co–Fe–B treated with 5 M H₃PO₄ for 7 days were 1869 and 4536 mL/min/g_catalyst, respectively. The activation energies for MMT-H₃PO₄–CoB and MMT-H₃PO₄–Co–Fe–B catalyst samples were 49.5 and 38.90 kJ/mol.     

Effect of microwave irritated Co-B-Cr catalyst on the hydrolysis of sodium borohydride

In this work, Co-B-Cr catalysts were synthesized from CoCl₂.6H₂O and Cr(NO₃)₂ 9H₂O compounds by using NaBH₄ as chemical reducing agent at temperature range of 5–8°C. The microwave irradiation method utilized depends on different gas medium (N₂, Ar, CO₂), microwave power (0–1,000 W), and microwave applying time (0–20 min) to increase the catalytic activity of Co-B-Cr catalysis used in the hydrolysis of NaBH₄. It was found that the Co-B-Cr catalyst with best catalytic activity for NaBH₄ hydrolysis was produced under microwave conditions of N₂ gases for 15 min treatment time and 500 W applying power. Hydrolysis of NaBH₄ is completed in 500 s by using Co-B-Cr catalysis treatment optimum irradiation microwave conditions and it is completed in 1,200 s in the case of non-microwave treatment of Co-B-Cr catalyst. The effect of microwave irradiation on Co-B-Cr surface was investigated by using scanning electron microscopy analysis.     

CeO2 supported multimetallic nano materials as an efficient catalyst for hydrogen generation from the hydrolysis of NaBH4

Nowadays, there is still no suitable method to store large amounts of energy. Hydrogen can be stored physically in carbon nanotubes or chemically in the form of hydride. In this study, sodium borohydride (NaBH₄) was used as the source of hydrogen. However, an inexpensive and useful catalyst (Co–Cr–B/CeO₂) was synthesized using the NaBH₄ reduction method and its property was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), x-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) measurements. The optimized Co–Cr–B/CeO₂ catalyst exhibited an excellent hydrogen generation rate (9182 mLg_metal⁻¹min⁻¹) and low activation energy (35.52 kJ mol⁻¹). The strong catalytic performance of the Co–Cr–B/CeO₂ catalyst is thought to be based on the synergistic effect between multimetallic nanoparticles and the effective charge transfer interactions between the metal and the support material.     

A study on hydrogen generation from NaBH4 solution using Co-loaded resin catalysts

Hydrogen production via chemical processes has gained great attention in recent years. In this study, Co-based complex catalyst obtained by adsorption of Co metal to Amberlite IRC-748 resin and Diaion CR11 were tested for hydrogen production from alkaline NaBH₄ via hydrolysis process. Their catalytic activity and microstructure were investigated. Process parameters affecting the catalytic activity, such as NaOH concentration, Co percentage and catalyst amount, as well as NaBH₄ concentration and temperature were investigated. Furthermore, characteristics of these catalysts were carried out via SEM, XRD and FT-IR analysis. Hydrogen production rates equal to 211 and 221 ml min⁻¹ g_cat⁻¹ could be obtained with Amberlite IRC-748 resin and Diaion CR11 Co based complex catalysts, respectively. The activation energies of the catalytic hydrolysis reaction of NaBH₄ were calculated as 46.9 and 59.42 kJ mol⁻¹ for Amberlite IRC-748 resin and Diaion CR11 based catalysts respectively kJ mol⁻¹ from the system consisting of 3% Co, 10 wt% NaBH₄ and 7 wt% NaOH as well as 50 mg catalyst dosage. It can be concluded that Co-based resins as catalysts for hydrogen production is an effective alternative to other catalysts having higher rate.     

Ethylene glycol as an alternative solvent approach for very efficient hydrogen production from sodium borohydride with phosphoric acid and acetic acid catalysts

For the first time, phosphoric acid (H₃PO₄) and acetic acid (CH₃COOH) catalysts were used for efficient hydrogen (H₂) production from sodium borohydride (NaBH₄) ethylene glycolysis reaction. In this experimental study, the effects of ethylene glycol/water ratio, ethylene glycol/acid ratio, NaBH₄ concentration, acid concentration, and temperature were investigated. These ethylene glycol/water ratio experiments showed that the use of water alongside ethylene glycol negatively affects H₂ production. The hydrogen generation rate (HGR) values obtained for this ethylene glycolysis reaction with 1 M H₃PO₄ and 1 M CH₃COOH catalysts are 5800 and 4542 mLmin^-1, respectively. Also, the completion times of ethylene glycolysis reactions with these acids are 8 and 10 s, respectively. The n value obtained for ethylene glycolysis reactions according to the power-law kinetic model was 0.50. The activation energies obtained with H₃PO₄ and CH₃COOH catalysts were 24.45 kJ mol^?1and 33.23 kJ mol^?1, respectively.     

Magnetic dendritic KCC-1 nanosphere-supported cobalt composite as a separable catalyst for hydrogen generation from NaBH4 hydrolysis

The introduction of magnetism into a catalyst can greatly optimize its separation performance. In the present work, a kind of magnetically separable catalysts for promoting NaBH₄ hydrolysis have been fabricated by anchoring cobalt nanoparticles on magnetic dendritic KCC-1 nanospheres composed of magnetic Fe₃O₄ core and fibrous shell. The fabricated catalysts were characterized with various characterization methods, including absorption spectroscopy (AAS), scanning electron microscopy (SEM), high-resolution transmission electronic microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), and Fourier transform infrared (FT-IR), etc. This kind of catalysts exhibit high catalytic activity for promoting the hydrolysis of NaBH₄ under alkaline conditions, giving a hydrogen generation rate and activation energy of 3.83 L min⁻¹ g_Co⁻¹ (30 °C) and 53.63 kJ mol⁻¹, respectively. After used for 5 cycles, the catalyst showed 36.5% catalytic activity reserved. Most importantly, the magnetism of the catalyst made it easily separated and recycled from the solution after the reaction completed. The development of this kind of catalysts could provide a promising option for catalyzing NaBH₄ hydrolysis for portable hydrogen production from.     

Conversion of hydrogen/carbon dioxide into formic acid and methanol over Cu/CuCr2O4 catalyst

Cu/CuCr₂O₄ catalysts were prepared by impregnation method at various calcination temperatures (300, 400, and 500 °C) and then reduced in H₂ stream. The aggregated particles and decreasing surface area/pore volumes of the deactivated catalysts during HCOOH and CH₃OH formations were also observed. Particularly, the EXAFS data showed that first shells of Cu atoms transforms from Cu–O to Cu–Cu after catalytic reactions, their bond distances and coordination numbers are quite different, respectively. It revealed that metallic Cu atoms are one of the important active species over catalyst surface at different reaction temperatures having many unoccupied binding sites for HCOOH and CH₃OH formations. Additionally, the optimal calcination temperature for Cu/CuCr₂O₄ catalysts was demonstrated at 400 °C that attributed to its strongest acidity and basicity. The catalytic reactions in the duration of HCOOH and CH₃OH preparation were proposed that were composed of HCOOH formation, CH₃OH formation, and CH₃OH decomposition happening at CuCr₂O₄, Cu, and CuO active sites, respectively. The highest CO₂ conversion (14.6%), HCOOH selectivity/yield (87.8/12.8%), and TON/TOF values (4.19/0.84) were obtained at 140 °C and 30 bar in 5 h, respectively. Optimal rate constant (2.57 × 10^?2 min^?1) and activation energy (16.24 kJ mol^?1) of HCOOH formation were evaluated by pseudo first-order model and Arrhenius equation, respectively.     

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.     

Effect of iron content on the hydrogen production kinetics of electroless-deposited CoNiFeP alloy catalysts from the hydrolysis of sodium borohydride,and a study of its feasibility in a new hydrolysis using magnesium and calcium borohydrides

The effect of Fe content in electroless-deposited CoNi-Fe_x-P alloy catalysts (x = 5.5–11.8 at.%) from the hydrolysis of NaBH₄ is investigated in alkaline sodium borohydride solution. The electroless-deposited CoNiFe_5.5-P and CoNiFe_7.6-P alloy catalysts are composed of flake-like micron particles; however, with an increase in Fe content to 11.8 at.%, the flake-like morphology is changed to a spherical shape and the crystal structure of the electroless-deposited CoNiFeP catalyst is transformed from FCC to BCC. Among all the CoNi-Fe_x-P alloy catalysts, the CoNi-Fe_x-P (x = 7.6 at.%) catalyst has the highest hydrogen production rate of 1128 ml min⁻¹ g⁻¹_catalyst in alkaline solution containing 1 wt% NaOH + 10 wt% NaBH₄ at 303 K. For the optimized catalyst, the activation energy of the hydrolysis of NaBH₄ is calculated to be 54.26 kJ mol⁻¹. Additionally, in this work, we report a new hydrolysis using Mg(BH₄)₂ and Ca(BH₄)₂. As a result, the Mg(BH₄)₂ is stored unstably in an alkaline solution, whereas the Ca(BH₄)₂ is stored stably. When optimizing the hydrogen production kinetics from the hydrolysis of Ca(BH₄)₂, the rate is 784 ml min⁻¹ g⁻¹_catalyst in 10 wt% NaOH + 3 wt% Ca(BH₄)₂ solution.     

Salicylaldimine-Ni complex supported on Al2O3: Highly efficient catalyst for hydrogen production from hydrolysis of sodium borohydride

In this study, the Ni-based complex catalyst containing nickel of 1% supported on Al₂O₃ is used as for the hydrogen production from NaBH₄ hydrolysis. The maximum hydrogen production rate from hydrolysis of NaBH₄ with Ni-based complex catalyst supported on Al₂O₃ containing nickel of 1% is 62535 ml min^?1 g^?1 (complex catalyst containing 1 wt% Ni). The resulting complex catalyst is characterised by XRD, XPS, SEM, FT-IR, UV, and BET surface area analyses. The Arrhenius activation energy is found to be 27.29 kJ mol^?1 for the nickel-based complex catalyst supported on Al₂O₃. The reusability of the catalyst used in this study has also been investigated. The Ni-based complex catalyst supported on Al₂O₃ containing nickel of 1% is maintained the activity of 100% after the fifth use, compared to the first catalytic use. The n value for the reaction rate order of NaBH₄ is found to be about 0.33.     

Effect of Al2O3-supported Cu-Schiff base complex as a catalyst for hydrogen generation in NaBH4 hydrolysis

Cu-Schiff base complex which we previously synthesized (Kilinc et al., 2012) is supported on Al₂O₃. The prepared catalyst is characterized by using SEM, XRD, BET, and FT-IR methods. And Al₂O₃-supported complex is used as a catalyst in NaBH₄ hydrolysis reaction for hydrogen generation. NaBH₄ hydrolysis reactions are investigated depending on the concentration of NaBH₄ and NaOH, temperature, percentage of Cu complex, and amount of catalyst. Maximum reaction rates are 44,453.33 and 57,410.00 mL H₂/g.cat.min at 30°C and 50°C, respectively. The activation energy of NaBH₄ hydrolysis reaction is found as 225,775 kJ^.mol^?1. All the experimental results and literature comparisons show that Al₂O₃-supported Cu-Schiff base complex is a very effective catalyst in NaBH₄ hydrolysis for H₂ generation.     

Catalytic hydrolysis of sodium borohydride on Co catalysts

The addition of NaBH₄ to Co–ethylenediaminetetraacetate (Co–EDTA) and Co–citrate solutions at 25 °C does not lead to generation of hydrogen. However, in the presence of Co‐based catalysts synthesized via chemical reduction of Co–EDTA and Co–citrate complexes with NaBH₄ at elevated temperature, an intensive generation of H₂ took place. In this study, the reduction mechanism of both complexes was elucidated by using various techniques. From the results of attenuated total reflection and mass spectrometry analysis, it was suggested that NaBH₄ was oxidized to NaBO₂ and that organic ligands of Co complexes were decomposed to gaseous hydrocarbons, such as C₂H₄, C₃H₄, and/or C₂H₃N. Structural characterizations of X‐ray diffraction, scanning transmission electron microscopy, transmission electron microscope, energy‐dispersive spectroscopy, and X‐ray photoelectron spectra on the catalysts revealed that Co(OH)₂, metallic cobalt, and cobalt borate were obtained in both cases. The morphology of Co(OH)₂ and the dispersion of metallic cobalt and cobalt borate nanoparticles were significantly different. In the case of the catalyst prepared from Co–EDTA, the nanoparticles of Co species aggregated with diameters from 100 to several hundred nanometers on Co(OH)₂ slabs. On the catalyst prepared from Co–citrate, the Co(OH)₂ formed sheets, and the nanoparticles of Co species formed clusters of 5–10 nm in diameter, which are dispersed well on the Co(OH)₂ sheet. The catalyst obtained from Co–citrate showed higher catalytic activity on hydrolysis reaction of NaBH₄ than that from Co–EDTA. Copyright © 2016 John Wiley & Sons, Ltd.