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103.
Dapeng Liu Yifan Wang Daming Shi Xinli Jia Xin Wang Armando Borgna Raymond Lau Yanhui Yang 《International Journal of Hydrogen Energy》2012
Carbon dioxide reforming of methane to synthesis gas was studied over Ni/ZrO2–SiO2 catalyst under different pretreatment atmospheres. Characterization using powder X-ray diffraction, H2 temperature-programmed reduction, H2 temperature-programmed hydrogenation, TG/DTA, XPS, Raman spectra and transmission electron microscopy techniques revealed that gas atmospheres employed in the catalyst pretreatment have a significant influence on the catalytic performance. The helium-pretreated catalyst was found to be the most suitable catalyst for this application, showing the improved catalytic performance. More specifically, helium pretreatment facilitated the generation of well-distributed active metal sites while the heterogeneity of Ni components upon H2 pretreatment degraded catalytic activity of metal sites considerably. Pretreatment under CO atmosphere resulted in the formation of carbon encapsulated metal species thus causing catalyst deactivation severely. Inefficient reduction under CH4 activation and the presence of a great amount of carbonaceous species, disfavor the production of synthesis gas during the dry reforming. 相似文献
104.
战场条件下装备战损零部件表面清洗与预处理是装备战场应急维修或再制造过程中的重要工序,本文通过喷砂实验,采用单纯CaCO2、棕刚玉及石英砂磨料,对45钢及7A52型装甲铝合金进行喷砂处理,借助X射线应力测定仪、扫描电子显微镜(SEM)、划痕测试仪等检测设备对一定喷砂条件下喷砂后试件表面形貌、粗糙度变化及应力状态等进行测试分析。研究结果表明采用纯CaCO2磨料在试样表面喷砂后的粗糙度值较低,纯棕刚玉磨料的粗糙度值较高,采用经过混合后的磨料喷射后的表面粗糙度介于两者之间,并且经过喷砂后被喷射表面应力为压应力,对喷砂后应力状态影响的重要性次序依次是:粒径、流量、压强和距离。 相似文献
105.
Ken-Lin ChangJitladda Thitikorn-amorn Jung-Feng HsiehBay-Ming Ou Shan-He ChenKhanok Ratanakhanokchai Po-Jung HuangShui-Tein Chen 《Biomass & bioenergy》2011,35(1):90-95
Production of bioethanol by the conversion of lignocellulosic waste has attracted much interest in recent years, because of its low cost and great potential availability. The pretreatment process is important for increasing the enzymatic digestibility of lignocellulosic materials. Enzymatic conversion with freeze pretreatment of rice straw was evaluated in this study. The freeze pretreatment was found to significantly increase the enzyme digestibility of rice straw from 48% to 84%. According to the results, enzymatic hydrolysis of unpretreated rice straw with 150 U cellulase and 100 U xylanase for 48 h yielded 226.77 g kg−1 and 93.84 g kg−1 substrate-reducing sugars respectively. However, the reducing sugar yields from freeze pretreatment under the same conditions were 417.27 g kg−1 and 138.77 g kg−1 substrate, respectively. In addition, hydrolyzates analysis showed that the highest glucose yield obtained during the enzymatic hydrolysis step in the present study was 371.91 g kg−1 of dry rice straw, following pretreatment. Therefore, the enhanced enzymatic conversion with freeze pretreatment of rice straw was observed in this study. This indicated that freeze pretreatment was highly effective for enzymatic hydrolysis and low environmental impact. 相似文献
106.
The effect of zinc immersion pretreatment on the quality and properties of Ni deposited layer on the AZ91D Mg alloy has been studied. The evolution of surface morphology, composition and microstructure of the AZ91D Mg alloy in the process of pretreatment was characterized by scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX) and X-ray diffraction (XRD). The results showed that the activation step results in the deposition of some composite membranes consisted of fluoride and phosphate or pyrophosphate formed preferentially in the α phase region of the Mg alloy surface, while zinc immersion leads to the deposition of a network-like Zn layer formed preferentially in the β phase region of the Mg alloy surface. Cyclic voltammogram, dynamic potential scanning polarization technique and chronopotentionmetry measurements showed that the deposited Zn layer can markedly improve the anti-corrosion ability of the Mg alloy substrate in the Ni-plating solution and improve the nucleation and growth of Ni onto the surface of the Mg alloy substrate. With the proper Zn immersion pretreatment, a compact Ni layer can be electro-deposited on the magnesium alloy. The deposited Ni layer shows good adhesion to the Mg alloy substrate. The Mg alloy specimens after deposition of Ni have good anti-corrosion properties in a neutral 3.5 wt.% NaCl solution. 相似文献
107.
Yong-Hun Cho Jinho Kim Tae-Yeol Jeon Namgee Jung Ju Wan Lim Won-Sub Yoon Yung-Eun Sung 《Journal of power sources》2010,195(18):5952-9515
A catalyst-coated membrane (CCM) as used in the membrane electrode assembly (MEA) of a polymer electrolyte membrane fuel cell is treated by dilute sulfuric acid solution (0.5 M) at boiling temperature for 1 h. This treatment improves the single-cell performance of the CCM without further addition of Pt catalyst. The changed microstructure and electrochemical properties of the catalyst layer are investigated by field emission scanning electron microscopy with energy dispersive X-ray, mercury intrusion porosimetry, waterdrop contact angle measurement, Fourier transform-infrared spectrometry in attenuated total reflection mode, electrochemical impedance spectroscopy, and cyclic voltammetry. The results indicate that this pretreatment enhances MEA performance by changing the microstructure of the catalyst layer and thus changing the degree of hydration, and by modifying the Pt surface, thus enhancing the oxygen reduction reaction. 相似文献
108.
A constructed microbial consortium was formulated from three facultative H2-producing anaerobic bacteria, Enterobacter cloacae IIT-BT 08, Citrobacter freundii IIT-BT L139 and Bacillus coagulans IIT-BT S1. This consortium was tested as the seed culture for H2 production. In the initial studies with defined medium (MYG), E. cloacae produced more H2 than the other two strains and it also was found to be the dominant member when consortium was used. On the other hand, B. coagulans as a pure culture gave better H2 yield (37.16 ml H2/g CODconsumed) than the other two strains using sewage sludge as substrate. The pretreatment of sludge included sterilization (15% v/v), dilution and supplementation with 0.5% w/v glucose, which was found to be essential to screen out the H2 consuming bacteria and ameliorate the H2 production. Considering (1:1:1) defined consortium as inoculum, COD reduction was higher and yield of H2 was recorded to be 41.23 ml H2/g CODreduced. Microbial profiling of the spent sludge showed that B. coagulans was the dominant member in the constructed consortium contributing towards H2 production. Increase in H2 yield indicated that in consortium, the substrate utilization was significantly higher. The H2 yield from pretreated sludge (35.54 ml H2/g sludge) was comparatively higher than that reported in literature (8.1–16.9 ml H2/g sludge). Employing formulated microbial consortium for biohydrogen production is a successful attempt to augment the H2 yield from sewage sludge. 相似文献
109.
在锌精矿的沸腾焙烧过程中,温度高于650℃时,生成的氧化锌及氧化铁结合成铁酸锌,是一种难溶于稀硫酸的铁氧体,全部留在浸出渣中。高温高酸浸出条件控制愈好,铁酸锌被溶解的愈多,硫化锌被破坏的就愈彻底,渣含锌就愈低,金属回收率就愈高,而且有利于银的浮选。针对某冶炼厂湿法炼锌渣,采用高温高酸浸出和浮选的方法回收锌、银,高温高酸浸出液经过除铁得到的溶液返回锌系统回收锌,高温高酸浸出渣经过一次粗选两次精选三次扫选的试验流程,得到了品位达到了2017.45g/t,回收率达到78.44%的银精矿。 相似文献
110.
Effects of pretreatment methods on solubilization of beet-pulp and bio-hydrogen production yield 总被引:1,自引:0,他引:1
Leyla OzkanTuba H. Erguder Goksel N. Demirer 《International Journal of Hydrogen Energy》2011,36(1):382-389
Sugar processing wastewater and beet-pulp are two major waste streams of sugar-beet processing plants. Contrary to wastewater, beet-pulp is generally used as animal feed in cattle-raising industry. However, it can serve as a substrate for bio-hydrogen production which corresponds to a higher valorization of beet-pulp. Moreover, pretreatment of lignocellulosic materials like beet-pulp is needed in order to improve overall energy efficiency and enable economic feasibility of bio-hydrogen production. Therefore, the effect pretreatment methods (alkaline, thermal, microwave, thermal-alkaline and microwave-alkaline) on bio-hydrogen production from sugar beet-pulp through dark fermentation were investigated in this study. Reactors pretreated with alkaline, microwave-alkaline and thermal-alkaline methods yielded significant solubilization of beet-pulp compared to others. Therefore, in the second phase of the study, they were used to pretreat the beet-pulp which was then subjected to dark fermentation for bio-hydrogen production. Maximum bio-hydrogen production yield of 115.6 mL H2/g COD was observed in reactor which contained alkaline pretreated beet-pulp. 相似文献