氢含量对Al-P中间合金变质效果的影响

利用测氢仪等测试手段研究了 ZL1 0 9熔体中氢含量对 Al- P中间合金变质效果的影响。结果表明 ,在相同的铸造条件下 ,变质后合金中熔体氢含量越高 ,初晶 Si晶粒的平均晶粒尺寸和最大晶粒尺寸越大。保温时间过长合金熔体有吸氢倾向 ,初晶 Si尺寸有增大趋势。在精炼处理充分的条件下 ,Al- P中间合金的变质效果可保持 3 0小时不失效     

吸氢合合蓄电池

吸氢合金在适当的温度和压力条件下与氢反应,形成氢化物。一般说来,加热或减压,氢化物就分解,放出氢来。这种吸氢的原理是这样的:(1)在合金表面分子氢分解成原子氢;(2)这种原子氢向合金内部扩散,产生固溶;(3)形成氢化物。这种反应的驱动力是热或氢的压力。利用这种热或压力引起的氢的吸放过程可以实现热——化学能转换,热——机械能转换,以氢的形式储能和输送能量,用于制作化学热泵、驱动器以及氢压缩机。近年来,在这些方面进行的研究很多。另外,不利用温度和压力的变化,而利用电作为驱动力,也能造成吸氢合金对氢的吸放。也就是说,把吸氢合金浸在电解液(浓碱溶液)中,把它作为负电极加上电压,就能将水电解,合金表面产生原子氢,     

镀铂电极在硫化氢间接电解法中的应用

利用间接电解法从硫化氢中制取氢气和硫磺是一种充分利用硫化氢资源的新方法,该文论述了镀铂电极在硫化氢间接电解法中的应用,一种新的固体电解质电极制作方法,对电极析氢性能的测试,电解液的改变对电解性能的影响,实验表明：镀铂电极的表面负载的PTFE乳液具有为阳极柏氢提供疏水孔道和阻碍电极导电性能的双重作用,其含量有一个最佳值,大约为25％－40％,Nafion溶液在Pt电极上的负载有利于Ｈ^ 在阳,极阴间的传递,且镀铂电极的表面负载的Ｎafion溶液的含量升高,电极的析氢性能愈好,电解液的酸度愈大,交换电流密度愈大,电极的析氢性能愈好,在实验范围内,Ｆe^ 2 ,Fe^3 ,|H^ |H2电解受氢离子扩散控制,阳极电解液的种类及其浓度的改变对电极性能的影响并不显著。     

纯铜、纯钴电极和铜钴合金电极在碱性介质中的光电化学研究

用动电位伏安法对纯铜电极、纯钴电极以及含钴量5.1%、9.7%、15%、25%和40%的铜钴合金电极在硼砂—硼酸缓冲溶液(pH8.5)中的光电化学行为进行了研究。纯铜电极、纯钴电极和铜钴合金电极均显示P-型光响应,纯铜电极的光响应来自Cu2O,纯钴电极的光响应主要来自Co3O4,铜钴合金电极的光响应来自Cu2O和Co3O4的共同作用。纯铜电极在阳极氧化过程中存在着Cu的阳极溶解和电极表面生成Cu2O膜的反应,温度升高有利于Cu2O膜的生成,除氧与否影响纯铜电极的成膜反应。纯钴电极电位正向扫描时不显示光响应,负向扫描时显示阴极光电流。铜钴合金电极的光响应随含钴量而变化。     

利用金属氢化物回收废热发生蒸汽的系统

日本化学技术公司、积水化学工业公司、中央电气工业公司和工学院大学联合开发了利用金属氢化物有效回收废热的实用化系统。经过1983～1985年三年的研究开发,1986年3月建成20冷冻吨的热泵热回收系统。 该系统利用贮氢合金技术,贮氢合金是具有可贮藏和释放大量氢气的有可逆功能的合金。吸氢时放热,反之,释氢时吸热,利用吸氢、释氢时的放热、吸热作用进行能量转换。表1是几种典型的吸氢合金的性能。     

微生物电解池处理PTA废水及同步产氢的研究

将微生物电解池应用于PTA废水的处理,系统研究PTA降解程度及同步产氢情况,并通过伏安曲线对电子传递机制进行研究。实验结果表明,微生物电解池可实现PTA废水的同步处理及产氢,当底物COD浓度为1000mg/L时,在外加电压0.900V的条件下,微生物电解池运行43h后,TA降解率和COD去除率分别为92.0%和80.3%,氢气产率为0.04m3/(m3·d),库仑效率为29%。     

生物制氢反应系统的启动负荷与乙醇型发酵

采用连续流搅拌槽式反应器(CSTR),以糖蜜废水为底物,研究了COD容积负荷对生物制氢反应系统启动过程中形成的乙醇型发酵产氢能力的影响。研究表明,在污泥接种量不小于6.24 gVSS/L、启动负荷为7.0 kgCOD/m3.d、水力停留时间(HRT)为6 h、系统pH、氧化还原电位(ORP)分别在4.0~4.3、-440~-470mV之间等条件下,可在30 d内完成乙醇型发酵菌群的驯化,实现生物制氢反应系统的快速启动。由不同启动负荷(3.0、7.0、10.0 kgCOD/m3.d)条件下形成的乙醇型发酵菌群,在相同的运行条件下其产氢能力存在着差异。当系统容积负荷为30 kgCOD/m3.d时,由启动负荷为7.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群比由启动负荷为3.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群产氢能力高56%。     

纯铜、纯然电极和铜钴合金电极在碱性介质中的光电化学研究

用动电位伏安法对纯铜电极,纯钴电极以及含钴量5.1%,9.7%,15%,25%和40％的铜钴合金电极在硼砂－硼酸缓冲溶液（pH8.5)中的光电化学行为进行了研究,纯铜电极,纯钴电极和铜钴合金电极均显示P－型光响应,纯铜电极的光响应来自Cu2O,纯钴电极的光响应主要来自Co3O4,铜钴合金电极的光响应来自Cu2O和Co3O4的共同作用,纯铜电极在阳极氧化过程中存在着Cu的阳极溶解和电极表面生成Cu2O膜的反应,温度升高有利于Cu2O膜的生成,除氧与否影响纯铜电极的成膜反应,纯钴电极电位正向扫描时不湿示光响应,负向扫描时显示阴极光电流,铜钴合金是极的光响应随含钴量而变化。     

金属氢化物复合式高压储氢器的研究

为提高高压储氢容器的体积储氢密度,采用具有高体积储氢密度的储氢合金与轻质高压容器复合组成高压金属氢化物复合式储氢器.为获得高压氢源,研究了Mm-Ml-Ni-Al(Mm为富铈混合稀土,Ml为富镧混合稀土)的储氢特性,并试制了化学热压缩器.采用研制的高压氢源,对具有高吸放氢平台压力的Ce-Ni系合金的高压储氢特性进行了研究.实验结果表明:以Ml或Ca部分取代Mm以及Al对Ni的部分置换后合金活化性能和吸放氢压力滞后明显改善,(Mm-Ml)0.8Ca0.2(Ni-Al)多元合金具有较好的储氢性能,适合于作为化学热压缩合金.CeNi5基多元合金在40MPa氢压条件下,合金具有较好的活化性能和吸放氢动力学性能,合金最大储氢容量分别达到1.6wt%.将优化的储氢合金与自制的轻质高压储氢容器复合组成的金属氢化物复合式高压储氢器,当储氢合金的填充量达到0.2(体积分数)时,其体积储氢密度提高50%.     

基于UASB反应器的厨余厌氧发酵产氢研究

针对目前厨余连续流发酵产氢处理负荷不高、产氢率较低的难题,采用UASB反应器进行厨余发酵产氢研究。在温度为30℃,进水COD浓度为2 000~10 000 mg/L,水力停留时间为2~6 h条件下,产氢速率最大达到17.04 L/(L.d)。反应器内有颗粒污泥的形成,平均生物量达到6.17 g/L,为氢气的产生提供了有利保障。当出水pH为4.2~4.4,碱度为260~340 mg/L的条件下,乙醇和乙酸占挥发酸总量的89.2%,形成稳定的乙醇型发酵类型,反应器最高处理负荷COD达到60 kg/(m3.d)。试验结果表明,UASB反应器具有更高的产氢效能和更加稳定的产氢效果,能够为厨余发酵产氢提供有利的保障。     

Energy and exergy analysis of hydrogen production from ammonia decomposition systems using non-thermal plasma

In the current study, the energy and exergy efficiencies of three hydrogen production systems from ammonia decomposition using dielectric barrier discharge plasma (DBD) were comparatively evaluated. The hydrogen gas was separated in a cylindrical plasma membrane reactor (PMR) using the Pd–Cu40% membrane with a thickness of 20 μm. The pre-catalytic reactor (CR) is added to the second system (CR-PMR), additionally, the CR is filled with the catalytic material type of 2%Ru/Al₂O₃ and the CR temperature is raised to 450 °C. Furthermore, the zeolite material type of SA-600 A was added to the PMR in the third H₂ production system (PMR) to enhance the hydrogen permeation through the Pd–Cu membrane. The hydrogen production rate was enhanced by combining the plasma and zeolite material in the third system (CR-CPMR). Moreover, the maximum obtained hydrogen production rates were 2.66, 81.6, and 96.6% in PMR, CR-PMR, and CR-CPMR or catalytic PMR, respectively. Also, it was observed that the energy efficiency increased by adding the CR to the system, while, the exergy efficiency values of all ammonia decomposition systems were still low due to the effect of system irreversibility. Additionally, the maximum energy efficiencies values were 0.8, 16.1, 44.1%, while the maximum exergy efficiencies values were 0.156, 4.91, and 6.344% for PMR, CR-PMR, and CR-CPMR, respectively. The exergy destruction rate of all NH₃ decomposition systems was still high although using the modified systems. The depletion factor is enhanced with the feeding ammonia flow rate increased while the sustainability index decreased at the same flow rates. Moreover, it was seen that the depletion factor results of PMR only were higher than other systems due to the exergy destruction rate was high.     

Hydrogen generation from sodium borohydride with Ni and Co based catalysts supported on Co3O4

Hydrogen is an alternative and clean energy carrier, but there are still some production related problems. In this aspect, it is crucial to efficiently generate hydrogen from hydrogen rich materials such as sodium borohydride. In this study, Co₃O₄ supported Ni and Co catalysts are synthesized via microwave irradiation technique for hydrogen generation from sodium borohydride. In this context, firstly, Co₃O₄ support material is synthesized by chemical method. Then, Ni and Co catalysts are decorated onto Co₃O₄ support material by microwave irradiation-polyol method. Prepared catalysts and support material are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-mass spectrometer (ICP/MS). A new system is designed by our group in order to determine the activity of the prepared catalysts for hydrogen generation. The effects of different initial NaOH concentrations on hydrogen generation rate are investigated. It is observed that the rate of hydrogen generation increased with an increase in initial NaOH concentration. Co-Co₃O₄ catalyst at 10% NaOH initial concentration shows the highest hydrogen generation rate as 2823 ml/g_cat.min. In summary, Co-based catalysts are exhibited more activity than Ni-based catalysts in terms of hydrogen generation.     

Improvement of hydrogen production with Rhodopseudomonas palustris CQK-01 by Ar gas sparging

For improving photo-biohydrogen production, a novel gas bubble column photobioreactor with Ar gas sparging was developed for biohydrogen production by purple non-sulfur phototrophic bacteria, Rhodoseudomonas palustris CQK-01. The dissolved hydrogen concentration was in-situ measured by a hydrogen microsensor. Experimental results demonstrated that Ar gas sparging dramatically decreased the dissolved hydrogen concentration, resulting in an improvement in the photo-biohydrogen production performance. Furthermore, effects of the gas flow rate and the time interval of gas sparging were investigated. The results showed that with an increase in the gas flow rate, the hydrogen production performance increased initially due to the reduced dissolved hydrogen concentration and enhanced mass transport, and then it decreased as a result of an increased shear stress. Meanwhile, the short sparging time interval resulted in a low accumulation of dissolved hydrogen in the bioreactor, hence high hydrogen production performance. The optimal hydrogen production rate (5.86 mmol/l/h) and hydrogen yield (3.38 mol H₂/mol glucose) were obtained at the gas flow rate of 10 ml/min, respectively.     

Hydrogen production from solid sodium borohydride with hydrogen peroxide decomposition reaction

This study investigates hydrogen production from solid sodium borohydride with hydrogen peroxide decomposition reaction for a fuel cell based air-independent propulsion system in space and underwater applications. Sodium borohydride in the solid state was used as a hydrogen source in the present study. Pure hydrogen could be generated by a catalytic hydrolysis reaction in which the water source was obtained from the hydrogen peroxide decomposition. Hydrogen peroxide was selected as an oxidizer, being decomposed catalytically to generate oxygen and water. The pure oxygen was provided to a fuel cell and the water was stored separately for the hydrolysis reaction. A fuel cell system was fabricated to validate the fuel cell based air-independent power system proposed in the present study. Two catalytic reactors were prepared; one for the solid sodium borohydride hydrolysis reaction and the other for the hydrogen peroxide decomposition reaction. The hydrogen and oxygen generation rate were measured based on the various conditions. The performance evaluation of a fuel cell system proposed in the present study was carried out.     

Preparation, testing and modelling of a hydrogen selective Pd/YSZ/SS composite membrane

A palladium selective tubular membrane has been prepared to separate and purify hydrogen. The membrane consists of a composite material, formed by different layers: a stainless steel support (thickness of 1.9 mm), an yttria-stabilized zirconia interphase (thickness of 50 μm) prepared by Atmospheric Plasma Spraying and a palladium layer (thickness of 27.7 μm) prepared by Electroless Plating. The permeation properties of the membrane have been tested at different operating conditions: retentate pressure (1-5 bar), temperature (350-450 °C) and hydrogen molar fraction of feed gas (0.7-1). At 400 °C, a permeability of 1.1 × 10⁻⁸ mol/(s m Pa^0.5) and a complete selectivity to hydrogen were obtained. The complete retention of nitrogen was maintained for all tested experiment conditions, with both single and mixtures of gases, ensuring 100% purity in the hydrogen permeate flux.A rigorous model considering all the resistances involved in the hydrogen transport has been applied for evaluating the relative importance of the different resistances, concluding that the transport through the palladium layer is the controlling one. In the same way, a model considering the axial variations of hydrogen concentration because of the cylindrical geometry of the experimental device has been applied to the fitting of the experimental data. The best fitting results have been obtained considering Sieverts’-law dependences of the permeation on the hydrogen partial pressure.     

Cost analysis of wind-electrolyzer-fuel cell system for energy demand in Pınarbaşı-Kayseri

In this study, the hydrogen production potential and costs by using wind/electrolysis system in P?narba??-Kayseri were considered. In order to evaluate costs and quantities of produced hydrogen, for three different hub heights (50 m, 80 m and 100 m) and two different electrolyzer cases, such as one electrolyzer with rated power of 120 kW (Case-I) and three electrolyzers with rated power of 40 kW (Case-II) were investigated. Levelised cost of electricity method was used in order to determine the cost analysis of wind energy and hydrogen production. The results of calculations brought out that the electricity costs of the wind turbines and hydrogen production costs of the electrolyzers are decreased with the increase of turbine hub height. The maximum hydrogen production quantity was obtained 14192 kgH₂/year and minimum hydrogen cost was obtained 8.5 $/kgH₂ at 100 m hub height in the Case-II.     

Enhancement of batch biohydrogen production from prehydrolysate of acid treated oil palm empty fruit bunch

Carbohydrates from hydrolyzed biomass has been a potential feedstock for fermentative hydrogen production. In this study, oil palm empty fruit bunch (OPEFB) was treated by sulfuric acid in different concentrations at 120 °C for 15 min in the autoclave. The optimal condition for pretreatment was obtained when OPEFB was hydrolyzing at 6% (w/v) sulfuric acid concentration, which gave the highest total sugar of 26.89 g/L and 78.51% of sugar production yield. However, the best conversion efficiency of OPEFB pretreatment was 39.47 at sulfuric acid concentration of 4%. A series of batch fermentation were performed to determine the effect of pH in fermentation media and the potential of this prehydrolysate was used as a substrate for fermentative hydrogen production under optimum pretreatment conditions. The prehydrolysate of OPEFB was efficiently converted to hydrogen via fermentation by acclimatized mixed consortia. The maximum hydrogen production was 690 mL H₂ L⁻¹ medium, which corresponded to the yield of 1.98 molH₂/mol_xylose achieved at pH 5.5 with initial total sugar concentration of 5 g/L. Therefore, the results implied that OPEFB prehydrolysate is prospective substrate for efficient fermentative hydrogen conducted at low controlled pH. No methane gas was detected throughout the fermentation.     

Effect of the initial total solids concentration and initial pH on the bio-hydrogen production from cafeteria food waste

In this paper, the influence of the initial pH and the total solids (TS) concentration on hydrogen production from the organic fraction of cafeteria food waste at mesophilic conditions in batch reactors was determined. It was found that the yield and specific hydrogen production rate were influenced by the initial pH and the initial total solids concentration. The highest hydrogen production rate, 2.90 mmolH₂/d, was obtained at 90 gTS/L and a pH of 5.5. Under this condition, the TS and chemical oxygen demand (COD) removal were the lowest (10% as TS and 14% as COD). However, considering the specific values, the highest specific degradation rate (192.2 mLH₂/gVS_removed/d) was obtained with the lowest TS concentration and an initial pH of 7.0. It was found that the influence of the TS concentration on hydrogen production was more significant than that of the initial pH for this type of residues.     

Utilization of excess corn kernels for hydrogen gas biofuel production

Corn kernels are good candidates for production of various value-added products such as gas biofuel, hydrogen due to the carbohydrate-rich composition. In this study, widely grown corn, field corn kernels were dissolved in subcritical water at different temperatures to determine optimal thermal hydrolysis condition. Organic-rich hydrolysate obtained from hydrolysis process was gasified by aqueous-phase reforming (APR) for hydrogen gas production.Since hydrolysis at 200 °C resulted in significantly more total organic carbon release than other temperatures and the lowest amount of insolubilized solid residue. Different concentrations of this hydrolysate (diluted with water at different ratios) were evaluated for high yielding hydrogen gas production. Gasification performance of corn kernels was also compared with lignocellulosic biomass using corn stover as a representative biomass material.The hydrolysate with 2486 mg/L TOC concentration showed the best performance for hydrogen gas production (130 mL H₂/g corn) and left less amount of ungasified solid residue. Corn kernels produced 2.3 times more hydrogen gas compared to corn stover biomass. Thus, corn kernels are promising feed materials for APR process, and excess production of corn can be utilized for hydrogen gas production in higher yield and richer composition.