Maximum Hydrogen Generation Research Articles

Biohydrogen production from industrial wastewaters.

The feasibility of producing hydrogen from various industrial wastes, such as vinasses (sugar and tequila industries), and raw and physicochemical-treated wastewater from the plastic industry and toilet aircraft wastewater, was evaluated. The results showed that the tequila vinasses presented the maximum hydrogen generation potential, followed by the raw plastic industry wastewater, aircraft wastewater, and physicochemical-treated wastewater from the plastic industry and sugar vinasses, respectively. The hydrogen production from the aircraft wastewater was increased by the adaptation of the microorganisms in the anaerobic sequencing batch reactor.

Carbon nanotubes/aluminum composite as a hydrogen source for PEMFC

Al matrix composites reinforced with 0–5 vol. % carbon nanotubes (CNTs) were fabricated by spark plasma sintering (SPS) to examine their hydrogen generation properties from the hydrolysis of Al in 10 wt. % NaOH solution at room temperature. The 5 vol. % CNTs/Al composite exhibits a maximum hydrogen generation rate of 120 ml/min g, which is about 6 times higher than that of Al without CNTs due to the synergetic effects of the porous Al matrix, which has a large reaction area and galvanic corrosion between the Al matrix and the CNTs. The hydrogen gas generated from the hydrolysis of the CNTs/Al composite has high purity without any production of undesirable CO. PEMFC produced electricity at 10 A and 0.73 V for 13 min, with hydrogen generated from the hydrolysis of 3.5 g–5 vol. % CNTs/Al composite. The CNTs/Al composite was effectively used as a hydrogen source for PEMFC.

The highest catalytic activity in the hydrolysis of ammonia borane by poly(N-vinyl-2-pyrrolidone)-protected palladium–rhodium nanoparticles for hydrogen generation

The use of poly(N-vinyl-2-pyrrolidone)-protected palladium–rhodium nanoparticles (2.5±1.1nm) as highly efficient catalysts providing a record catalytic activity in the hydrolysis of ammonia borane for hydrogen generation is reported. They are prepared by co-reduction of palladium and rhodium metal ions in ethanol/water mixture by an alcohol reduction method and characterized by TEM-EDX analysis, UV–Vis spectroscopy, and X-ray photoelectron spectroscopy. They are recyclable and highly efficient catalysts for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing record average turnover frequency (1333mol H2 (mol cat)−1min−1), maximum hydrogen generation rate (36,414 L H2 min−1 (molcat)−1), and total turnovers (171,000). Poly(N-vinyl-2-pyrrolidone)-protected palladium-rhodium nanoparticles also provide activation energy of 46.1±2kJ/mol for the hydrolysis of ammonia borane.

Hydrogen Generation from Hydrolysis of Ball‐Milled Al/C Composite Materials: Effects of Processing Parameters

AbstractIn the present work a parametric investigation on hydrogen evolution by hydrolysis of ball‐milled Al/graphite composite materials with water is reported. The results showed that the addition of NaCl produced some favorable effects on the completeness of the Al hydrolysis reaction with water, particularly at low NaCl weight percentage levels, but deteriorated the Al reactivity due to large size agglomerates formed during milling process. Using a fine aluminum powder could improve the aluminum hydrolysis reactivity and increase hydrogen generation rate. The hydrogen evolution measurements showed that Al in pellet form exhibited poor hydrolysis reactivity, and increasing the aging time significantly degraded the Al reactivity. The hydrogen evolution rate of the Al/graphite composite materials is also dependent on reaction temperature, and the maximum hydrogen generation rate of 52.4 cm3 min−1 g−1 Al was obtained if the reaction temperature was increased to 75 °C.

Hydrogen generation by the hydrolysis of magnesium–aluminum–iron material in aqueous solutions

Abstract Highly activated Mg–Al–Fe materials are prepared from powder by mechanical ball milling method for hydrogen generation. The hydrolysis characteristics of Mg–Al–Fe materials in aqueous solutions under different experimental conditions are carefully investigated. The results show that the hydrolysis reactivity of Mg–Al–Fe material can be significantly improved by increasing the ball milling time and Fe content. The increase of NaCl solution concentration and initial temperature is also found to promote the hydrogen generation reaction. At 25 °C, the Mg60–Al30–Fe10 (wt%) material ball-milled for 4 h shows the best performance in 0.6 mol L−1 NaCl solution, and the reaction can produce 1013.33 ml g−1 hydrogen with a maximum hydrogen generation rate of 499.50 ml min−1 g−1. In comparison to NaCl solution, natural seawater is found to have an inhibiting effect on the hydrolysis of Mg–Al–Fe material. Especially, the presence of Mg2+ and Ca2+ in seawater can greatly reduce the hydrogen conversion yield, and the SO42− can decrease the hydrogen generation rate.

Al–Li3AlH6: A novel composite with high activity for hydrogen generation

Abstract A novel material for hydrogen generation with high capacity of H2 generation has been successfully prepared by ball milling the mixture of Al and home-made fresh Li3AlH6 powder. Its theoretical capacity of hydrogen released is higher than that of pure Al. Results obtained have shown conversion efficiency of Al–Li3AlH6 composite can be close to 100% by increasing the content of Li3AlH6. When the content of Li3AlH6 is 20 wt%, the maximum hydrogen generation rate and hydrogen yield are 2737.6 mL g−1 min−1 and 1513.1 mL g−1, respectively, at room temperature. By XRD, SEM analyses and reaction heat measurements, it demonstrates that the additive Li3AlH6 can provide an additional source of H2 and an alkaline environment (LiOH) as well as additional heat to promote the Al/H2O reaction. Therefore, the Al–Li3AlH6 composite has a very high activity and high capacity of hydrogen released.

Hydrogen generation from the hydrolytic dehydrogenation of ammonia borane using electrolessly deposited cobalt–phosphorus as reusable and cost-effective catalyst

The development of catalytically active, low-cost, and reusable catalysts is very vital for on-demand hydrogen generation systems for practical onboard applications. Titanium dioxide supported-cobalt–phosphorus (Co–P/TiO2) catalyst prepared by electroless deposition has been shown to effectively promote the release of hydrogen from the hydrolytic dehydrogenation of ammonia borane. The catalyst is very stable to be isolated as solid material and characterized by XRD, SEM-EDX, and XPS. It is redispersible and reusable as an active catalyst in the hydrolytic dehydrogenation of AB. The activation energy (Ea) for the hydrolytic dehydrogenation of ammonia borane catalyzed by Co–P/TiO2 catalyst is 48.1 ± 2 kJ mol−1. Maximum hydrogen generation rate in the hydrolytic dehydrogenation of ammonia borane catalyzed by Co–P/TiO2 catalyst is 2002 mL H2 min−1 (g catalyst)−1.

Hydrolysis of Sodium Borohydride and Ammonia Borane for Hydrogen Generation Using Highly Efficient Poly(N-Vinyl-2-Pyrrolidone)-Stabilized Ru–Pd Nanoparticles as Catalysts

The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized Ru–Pd nanoparticles (3.2 ± 1.0 nm) in the hydrolysis of sodium borohydride and ammonia borane is reported. These were prepared by the co-reduction of two metal ions in ethanol/water mixture by the alcohol reduction method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. These are recyclable and highly active for hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane even at very low concentrations and temperature, providing a record number of average turnover frequency values (762 mol H2/mol cat.min−1 and 308 mol H2/mol cat.min−1) and maximum hydrogen generation rates (22,889 L H2 min−1 (mol cat)−1 and 9364 L H2 min−1 (mol cat)−1) for sodium borohydride and ammonia borane, respectively. Poly(N-vinyl-2-pyrrolidone)-stabilized Ru–Pd nanoparticles provide activation energies of 52.4 ± 2 and 54.5 ± 2 kJ/mol for the hydrolysis of sodium borohydride and ammonia borane, respectively.

Hydrogen generation from hydrolysis of ammonia borane in the presence of highly efficient poly(N-vinyl-2-pyrrolidone)-protected platinum-ruthenium nanoparticles

Herein, the employment of PVP-protected Pt–Ru bimetallic nanoparticles (3.2±1.4nm) as highly efficient catalysts in the hydrolysis of ammonia borane for hydrogen generation is reported. They were prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by TEM–EDX analysis, UV–vis spectroscopy, and X-ray photoelectron spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing a record numbers of average TOF value (308molH2molcat−1min−1) and maximum hydrogen generation rate (9884LH2min−1(molcat)−1) for ammonia borane. PVP-protected Pt–Ru bimetallic nanoparticles provide activation energy of 56.3±2kJmol−1 for the hydrolysis of ammonia borane.

Hydrogen generation from Mg–LiBH4 hydrolysis improved by AlCl3 addition

On-site on-demand hydrogen generation from a new Mg–LiBH4–AlCl3 system has been established. The hydrogen yield, mHGR (maximum hydrogen generation rate) and reaction stability can be adjusted by changing the samples' compositions, milling time and water/mixture ratios. The Mg-9 wt.%LiBH4-1 wt.%AlCl3 composite reaches a conversion yield of 87%, corresponding to 1083.5 ml H2 g−1 (composite), and the mHGR is 1256.9 ml min−1 g−1 in 60 min at 298 K. The synergistic effect between Mg and LiBH4 as well as the catalytic effects of LiBH4–AlCl3 additives both contribute to the improved hydrolytic performances. Compared with the hydrolysis of single Mg or Mg–LiBH4 system, the Mg–LiBH4–AlCl3 mixture has greatly improved its hydrogen yield and mHGR. This mixture is promising for its application as portable hydrogen sources.

Shape-related optical and catalytic properties of wurtzite-type CoO nanoplates and nanorods

In this paper, we report the anisotropic optical and catalytic properties of wurtzite-type hexagonal CoO (h-CoO) nanocrystals, an unusual nanosized indirect semiconductor material. h-CoO nanoplates and nanorods with a divided morphology have been synthesized via facile solution methods. The employment of flash-heating and surfactant tri-n-octylphosphine favors the formation of plate-like morphology, whereas the utilization of cobalt stearate as a precursor is critical for the synthesis of nanorods. Structural analyses indicate that the basal plane of the nanoplates is (001) face and the growth direction of the nanorods is along the c axis. Moreover, the UV–vis absorption spectra, the corresponding energy gap and the catalytic properties are found to vary with the crystal shape and the dimensions of the as-prepared h-CoO nanocrystals. Furthermore, remarkable catalytic activities for H2 generation from the hydrolysis of alkaline NaBH4 solutions have been observed for the as-prepared h-CoO nanocrystals. The calculated Arrhenius activation energies show a decreasing trend with increasing extension degree along the 〈001〉 direction, which is in agreement with the variation of the charge-transfer energy gap. Finally the maximum hydrogen generation rate of the h-CoO nanoplates exceeds most of the reported values of transition metal or noble metal containing catalysts performing in the same reaction system, which makes them a low-cost alternative to commonly used noble metal catalysts in H2 generation from the hydrolysis of borohydrides, and might find potential applications in the field of green energy.

Exploration of hydrogen generation from an Mg–LiBH4 system improved by NiCl2 addition

A novel method to promote the Mg–H2O hydrolysis reaction is proposed. Among the hydrides tested, LiBH4 offers the best performance. By ball-milling Mg powder with LiBH4, the maximum hydrogen generation rate (mHGR) and yield are significantly increased. More importantly, the hydrolysis properties are further improved when NiCl2 is added. The newly formed Mg–LiBH4–NiCl2 system reaches an mHGR of 1655 ml min−1 g−1 and yield of 96.1%. The factors influencing the hydrogen generation performance of this system, such as sample composition and milling time, are investigated. Different methods of characterization, such as X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy are used for the preliminary mechanistic study. The milling conditions and the in situ deposition of metallic Ni are both believed to be important factors that benefit the overall hydrolysis process.

Synthesis, structural characterization, and hydrolysis of Ammonia Borane (NH3BH3) as a hydrogen storage carrier

In the present study, synthesis, structural characterization, and hydrolysis of the promising hydrogen storage carrier ammonia borane (NH3BH3), were investigated. NH3BH3 was prepared by one-pot chemical reaction between sodium borohydride (NaBH4) and different ammonia salts [NH4X, X: SO4, CO3, Cl] in the presence of solvent, tetrahydrofurane (THF). Synthesizes with different temperatures (20–40 °C), reaction times (30–130 min), amount of added THF volume (50–200 ml) and NaBH4/(NH4)2SO4 input molar ratios (0.47–0.75) were performed in order to find the optimum reaction conditions for obtaining maximum product yield. The characterization of NH3BH3 products was carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), elemental analysis (C, H, N, O) and NMR spectroscopy. Characterization results indicated that NH3BH3 as a crystalline powder at 98% purity was achieved with 92.18% production yield. Additionally, hydrolysis of product NH3BH3 in the presence of amorphous Co–B catalyst at 22–80 °C under magnetic stirring (700 rpm) was performed. The maximum hydrogen generation rate was 5447.80 ml min−1 g cat−1 and the hydrolysis reaction kinetics were clarified based on zero-order, first-order and Langmuir–Hinshelwood kinetic models.

Dehydrogenation characteristics of ammonia borane via boron-based catalysts (Co–B, Ni–B, Cu–B) under different hydrolysis conditions

In the present study, dehydrogenation characteristics of ammonia borane (NH3BH3) catalyzed via boron-based catalysts under different hydrolysis conditions were investigated. A series of boron-based catalysts (Co1−x–Bx, Ni1−x–Bx, and Cu1−x–Bx, x: 0.25, 0.50, 0.75) were prepared by sol–gel method. Gels were calcinated at different temperatures (250 °C, 350 °C, and 450 °C) in order to obtain the boron-based catalysts. XRD characterizations revealed that Co–B, Ni–B, and Cu–B crystalline structures were formed during calcination at 450 °C. Hydrogen generation measurements were performed in order to determine the optimum composition of the boron-based catalyst. The maximum hydrogen generation rates were 7607 ml min−1 gcat−1, 3869 ml min−1 gcat−1 and 1178 ml min−1 gcat−1 for Co0.75B0.25, Ni0.75B0.25 and Cu0.75B0.25, respectively. Furthermore, the hydrolysis of NH3BH3 was performed at 20 °C, 40 °C, 60 °C and 80 °C under magnetic stirring (750 rpm), ultrasonic irradiation and non-stirring in order to determine how these parameters effect hydrolysis. Activation energies (Ea) were calculated by evaluation of the kinetic data. Under ultrasonic irradiation, the Ea in the presence of Co0.75B0.25, Ni0.75B0.25 and Cu0.75B0.25 were 40.85 kJ mol−1, 43.19 kJ mol−1 and 48.74 kJ mol−1, respectively, which compares favorably with results reported in the literature. Thus, the catalytic activities of the boron-based catalysts were found to be Cu < Ni < Co and the best reaction condition for the catalytic hydrolysis of NH3BH3 was determined to be non-stirring < magnetic stirring < ultrasonic irradiation.

An effective synthesis route for improving the catalytic activity of carbon-supported Co–B catalyst for hydrogen generation through hydrolysis of NaBH4

A novel method for synthesis of carbon-supported cobalt boride catalyst was developed for hydrogen generation from catalytic hydrolysis of NaBH4 solution. The activated carbon and carbon black supported catalysts prepared by “reduction–precipitation” method were found to be much more active than those prepared by conventional “impregnation–reduction” method inspite of the same Co content. A maximum hydrogen generation was achieved using carbon black supported Co–B, which lowers the activation energy to 56.7kJmol−1. The effects of NaOH concentration (1–15 wt.%), NaBH4 concentration (5–20 wt.%) and reaction temperature (25–40°C) on the performance of the most active catalyst (Co–B/CB) were investigated in detail. The results indicated that this catalyst can be used in a hydrogen generator for mobile applications such as PEMFC systems due to its high catalytic activity and simple preparation method.

Solid state preparation and reaction kinetics for Co/B as a catalytic/acidic accelerator for NaBH4 hydrolysis

In this study, the solid state synthesis and reaction kinetics for Co/B as a catalytic/acidic accelerator for sodium borohydride (NaBH4) hydrolysis were investigated. The Co/B a catalytic/acidic accelerator was synthesized from cobalt(II) chloride hexahydride (CoCI2·6H2O) and boron oxide (B2O3) by a procedure based on solid state synthesis. Differential thermal analyses (DTA) were performed on mixtures of CoCI2·6H2O and B2O3 at four different heating rates (5, 10, 15 and 20 °C min−1) in order to determine the solid state reaction temperatures. Kissinger and Doyle kinetic models were applied to the reaction kinetics data for the solid state preparation. The ideal temperature for the solid-state synthesis of Co/B catalytic/acidic accelerator was 196 °C. Additionally, the catalytic behavior of solid state synthesized Co/B as an catalytic/acidic accelerator for NaBH4 hydrolysis was investigated. The hydrolysis reactions were performed at temperatures of 22, 40, and 60 °C and the experimental data were fitted to zeroth, first, and second order kinetic models. The maximum hydrogen generation rate was 5,470 ml H2 min−1 g−1 cat and Ea was only 48.07 kJ mol−1.

화학수소화합물을 이용한 소형 무인항공기용 연료전지 시스템 연구 - I. 경량 수소 발생 및 제어 장치

소형 무인항공기의 동력장치로 연료전지 시스템을 적용하기 위해 화학수소화합물 수소 저장방법을 이용한 소형 수소 발생 제어장치를 설계하였다. 효율이 높은 소형/경량 수소 발생 제어장치를 설계하기 위하여 <TEX>$NaBH_4$</TEX> 수용액 공급 유량에 따른 Co-B 촉매의 수소 전환율을 확인하였고, 100W 스택의 최대 수소 발생량에 적합한 Co-B 촉매양을 제안하였다. 효율적인 연료 소모를 위해 Dead-end 방식의 스택을 선택하였고, 수소 발생 제어장치 내부 압력을 이용한 펌프 on/off 제어로 수소 생성량을 제어하였다. 소형 수소 발생 제어장치를 이용한 연료전지 시스템의 각 작동구간에서 안정된 운전을 확인하였다. 장시간 운전 실험을 통하여 최대 7시간 운전이 가능하며, 임의의 비행 프로화일에 요구되는 추력 프로화일은 최소 4시간 이상 조정 가능함을 확인하였다. A compact hydrogen generation device of fuel cell system using chemical hydride storage technique was designed to fit the propulsion device requirement of a small unmanned aerial vehicle(SUAV). For high efficient, compact, and lightweight hydrogen generation control device, the Co-B catalyst hydrogen conversion rate by <TEX>$NaBH_4$</TEX> aqueous solution flux is measured so that the proper amount of Co-B catalyst for maximum hydrogen generation of 100W stack was proposed. A compact hydrogen generation device is controlled by pump's on/off using its own internal pressure and consumes fuel in high efficiency through a dead-end type fuel cell. The fuel cell system has stable operation for a planed flight profile. The system operates up to maximum 7 hours and at least 4 hours for tough flight profiles.

In situ synthesized Fe–Co/C nano-alloys as catalysts for the hydrolysis of ammonia borane

Composite catalysts Fe0.3Co0.7-doped carbon aerogel have been in situ synthesized by chemical reduction method and successfully employed in the hydrolysis of NH3BH3 (AB) at room temperature. The mass percent of the doped Fe0.3Co0.7 alloys can reach to the maximum value of 40 wt%. The prepared catalysts exhibit excellent catalytic activity, especially for the specimen of 40 wt% Fe0.3Co0.7/C, which shows high catalytic activity and long durability. Its maximum hydrogen generation rate is as high as 13,695.6 ml min−1 g−1 at 298 K and the activation energy is only 20.83 kJ mol−1. Besides, this catalyst possesses preferable cycling stability at room temperature. The low cost, high catalytic activity and enhanced cycling stability can make it have a bright future in the application field of fuel chemistry.

Kinetics of sodium borohydride hydrolysis catalyzed via carbon nanosheets supported Zr/Co

Porous sheet-like activated carbon was prepared in a fluidized bed using peanut shell as carbon precursor. Cobalt and zirconium were impregnated onto the carbon by impregnation-chemical reduction method to obtain carbon nanosheets supported Co and Zr/Co catalysts. The samples were characterized using field emission scanning electron microscopy, X-ray diffraction, H2-temperature-programmed reduction, and nitrogen adsorption measurements. It was found that the introduction of zirconium to the carbon-supported cobalt led to an intensified interaction between cobalt and the support. With the activation energy of 34.84 kJ mol−1 and maximum hydrogen generation rate of 1708 mL min−1 g−1, this novel carbon-supported Zr/Co catalyst exhibited superior catalytic activity for the hydrolysis of NaBH4 in alkaline medium. Furthermore, the effects of temperature, catalyst amount, and concentration of NaOH and NaBH4 on the hydrolysis process were systematically studied, and an overall kinetic rate equation was described as r = Ae−34840/(RT)[catalyst]1.53[NaOH]−0.54[NaBH4]0.43.

A novel perspective for hydrogen generation from ammonia borane (NH3BH3) with Co–B catalysts: “Ultrasonic Hydrolysis”

In this study, a novel perspective has been proposed as “Ultrasonic Hydrolysis” for hydrogen generation from ammonia borane (NH3BH3) with cobalt–boron (Co–B) catalysts. The Co–B catalysts are prepared by the sol–gel reaction of boron oxide (B2O3) with cobalt(II) chloride hexahydrate (CoCI2.6H2O) in the presence of citric acid (C6H8O7). Two types of Co–B catalysts, amorphous and crystalline, are obtained after calcination at 500 and 700 °C respectively. The hydrolysis reactions are carried out in a batch reactor under ultrasonic conditions (frequency of irradiation of 35 kHz) at temperatures of 22, 40, 60 and 80 °C using 0.12 M NH3BH3 solution with amorphous and crystalline Co–B catalysts. The experimental data is fitted to zero-, first-, and second-order kinetic models and zero model gives good behavior description of the hydrogen generation rate. The maximum hydrogen generation rate is observed with amorphous Co–B catalyst (9157.20 ml.min−1 .g cat−1) and amount optimization, reusability and recyclability test are performed; TOF values for catalytic reactions were calculated. The corresponding activation energy (Ea) is only 47.50 kJ.mol−1 under ultrasonic conditions. In conclusion, the hydrogen generation rate has been increased by 37.79, 21.99, and 21.85% under ultrasonic conditions when the results are compared with 500, 750, and 1000 rpm magnetic stirring hydrolysis, respectively.