毕赤酵母提取液还原制备银纳米颗粒

采用毕赤酵母的提取液与银氨溶液反应制备银纳米颗粒(AgNPs),并考察了pH值对AgNPs的影响.结果表明:酸性条件下,反应速率缓慢,且生成的AgNPs呈多分散性;在一定范围内(pH值小于12.50),碱性条件有利于提高反应速率,且随着pH值的提高,AgNPs粒径分布变窄;当pH值继续提高(pH值为12.80),AgNPs发生团聚沉淀.     

纳米贵金属催化剂制备的研究进展

介绍了化学还原法、电化学法、化学气相沉积法、微波辅助法和模板法等纳米贵金属催化剂的制备方法,论述了各种方法的制备过程和研究进展,指出纳米贵金属催化剂现有的制备技术还不够成熟,较难实现工业化;纳米催化剂性能稳定控制技术尚未掌握,在空气中极易被氧化、吸湿和团聚,性能不够稳定等问题。需要在提高催化反应效率、优化反应途径和提高反应速率等方面进行广泛深入研究和探讨,尽早使纳米贵金属催化剂实用化。     

毕赤酵母干粉吸附还原氯金酸制备金纳米颗粒

采用毕赤酵母干粉吸附还原氯金酸(HAu Cl4)溶液制备金纳米颗粒,考察了还原条件(时间、p H值、温度、HAu Cl4浓度)对毕赤酵母干粉吸附[Au Cl4]-吸附量的影响。结果表明,在毕赤酵母干粉浓度为4 g/L,HAu Cl4为浓度1.00 mmol/L,溶液p H值为4、温度为30℃、吸附时间为40 min条件下,吸附量达到最大,49.75 mg/g。利用紫外-可见光谱、X射线粉末衍射、透射电镜对毕赤酵母干粉吸附还原氯金酸产物进行表征,证实产物为纳米金颗粒。通过毕赤酵母干粉吸附还原HAu Cl4前后的红外光谱图变化,发现毕赤酵母菌上的—COO-、多糖化合物的—OH和蛋白质的酰胺成分可能参与了[Au Cl4]-的生物吸附还原过程。     

毕赤酵母干粉吸附还原氯金酸制备金纳米颗粒

采用毕赤酵母干粉吸附还原氯金酸(HAu Cl4)溶液制备金纳米颗粒,考察了还原条件(时间、p H值、温度、HAu Cl4浓度)对毕赤酵母干粉吸附[Au Cl4]-吸附量的影响。结果表明,在毕赤酵母干粉浓度为4 g/L,HAu Cl4为浓度1.00 mmol/L,溶液p H值为4、温度为30℃、吸附时间为40 min条件下,吸附量达到最大,49.75 mg/g。利用紫外-可见光谱、X射线粉末衍射、透射电镜对毕赤酵母干粉吸附还原氯金酸产物进行表征,证实产物为纳米金颗粒。通过毕赤酵母干粉吸附还原HAu Cl4前后的红外光谱图变化,发现毕赤酵母菌上的—COO-、多糖化合物的—OH和蛋白质的酰胺成分可能参与了[Au Cl4]-的生物吸附还原过程。     

一种基于纳米碳纤维的贵金属电催化剂及其制备方法

本发明公开了一种基于纳米碳纤维的贵金属电催化剂及其制备方法。本发明基于纳米碳纤维的独特物理化学性能,利用电化学沉积和化学沉积方法的优点,摒弃电化学沉积和化学沉积方法     

制备钯金属纳米颗粒的还原方法及还原机理

对于燃煤的IGCC系统中,通过水煤气(CO+H2)的转换来分离H2/CO2,已成为捕集分离CO2主要手段,而对于具有独特透氢性能钯因素则是分离氢气的主要介质,钯掺杂的氢气分离膜则越来越被研究所关注。然而钯纳米颗粒粒径大小及钯的团聚问题已成为钯功能发挥的最大障碍,因此发展和完善钯纳米颗粒的合成和钯盐的还原则显得越来越重要。介绍钯还原方法和各还原剂的还原机理,特别是对现在最被研究者广泛应用的化学还原法做了较为详细的说明,为制备钯纳米颗粒提供一些参考,同时为实现钯掺杂的氢气分离膜的最大氢气透过率和分离性能,研究出一种低成本、高效率气体分离膜。     

磁纳米贵金属催化剂的制备及加氢性能

以有机分子聚乙烯亚胺为交联剂,四氧化三铁为载体,制备了贵金属催化剂用于催化硝基苯化合物加氢反应,采用FT - IR、XRD和TEM对催化剂进行表征.结果表明,制取的磁纳米贵金属催化剂催化对氯硝基苯加氢反应转化率高,稳定性较好,较容易回收.     

贵金属纳米核壳材料的研究进展及其应用

从单金属、双金属和多金属核壳体系3个方面系统综述了几种典型的贵金属金、铂、钯、铑等纳米核壳材料的研究进展及其在催化领域的相关应用,同时指出了目前该领域存在的问题,并对其发展方向进行了预测。     

非贵金属氧还原电极催化剂研究进展

质子交换膜燃料电池(PEMFC)中普遍使用Pt作为阴极电催化剂,但由于Pt价格昂贵、储量稀少,PEMFC中使用大量的Pt,必然导致PEMFC制造成本的上升。因此,寻找一种能够部分或者完全达到Pt催化效果的非贵金属催化剂,成为一种可行的方法。本文对近年来非贵金属氧还原电极催化剂的研究进行了总结,特别是不同催化剂的制备方法、反应机理及活性中心进行了梳理,并对非贵金属氧还原电极催化剂的发展进行了展望。     

低温燃料电池用非贵金属氧还原催化剂研究进展

非贵金属氧还原催化剂是近年来低温燃料电池最受关注的研究热点之一。本文回顾了作者课题组在低温燃料电池用非贵金属氧还原催化剂方面的研究进展,总结了提高催化活性和稳定性、降低催化剂制备成本、催化剂制备工艺和新型非贵金属氧还原催化剂设计等方面所取得的研究结果。对非贵金属氧还原催化剂亟待解决的问题和发展趋势提出自己的看法。     

贵金属硫化物催化剂的制备及其在催化加氢反应中的应用

贵金属硫化物催化剂对含硫化合物加氢、加氢脱硫、加氢脱氮和卤代硝基化合物加氢等方面有特殊应用,选择性高,不易失活.总结了国内外贵金属硫化物制备方法,综述了各类贵金属硫化物在催化加氢方面的应用,并对贵金属特别是Pd的不同种硫化物种间相互转变条件进行了探讨.     

State of arts on the bio-synthesis of noble metal nanoparticles and their biological application

Nanomaterials are materials in which at least one of the dimensions of the particles is 100 nm and below. There are many types of nanomaterials, but noble metal nanoparticles are of interest due to their uniquely large surface-to-volume ratio, high surface area, optical and electronic properties, high stability, easy synthesis, and tunable surface functionalization. More importantly, noble metal nanoparticles are known to have excellent compatibility with bio-materials, which is why they are widely used in biological applications. The synthesis method of noble metal nanoparticles conventionally involves the reduction of the noble metal salt precursor by toxic reaction agents such as NaBH₄, hydrazine, and formaldehyde. This is a major drawback for researchers involved in biological application researches. Hence, the bio-synthesis of noble metal nanoparticles (NPs) by bio-materials via bio-reduction provides an alternative method to synthesize noble metal nanoparticles which are potentially non-toxic and safer for biological application. In this review, the bio-synthesis of noble metal nanoparticle including gold nanoparticle (AuNPs), silver nanoparticle (AgNPs), platinum nanoparticle (PtNPs), and palladium nanoparticle (PdNPs) are first discussed. This is followed by a discussion of these biosynthesized noble metal in biological applications including antimicrobial, wound healing, anticancer drug, and bioimaging. Based on these, it can be concluded that the study on bio-synthesized noble metal nanoparticles will expand further involving bio-reduction by unexplored bio-materials. However, many questions remain on the feasibility of bio-synthesized noble metal nanoparticles to replace existing methods on various biological applications. Nevertheless, the current development of the biological application by bio-synthesized noble metal NPs is still intensively ongoing, and will eventually reach the goal of full commercialization.     

纳米氧化锌的生物法合成及固定脂肪酶的研究

采用植物乳杆菌合成了纳米氧化锌粒子并成功用于脂肪酶的固定化。将筛选得到的高耐硫酸锌的植物乳杆菌株LP4用于纳米氧化锌的合成,采用扫描电镜、透射电镜和X射线衍射等一系列分析测试手段对得到的产物进行了表征。结果显示合成的材料为直径9～35 nm球形颗粒,在359 nm处有最大吸收峰,晶体呈六方体纤锌矿结构,X射线衍射峰与标准纳米氧化锌对比结果一致,这些结果表明植物乳杆菌株LP4成功合成了纳米氧化锌。然后将合成得到的纳米氧化锌粒子用于固定假丝酵母(Candida sp.)脂肪酶,与普通氧化锌以及传统法合成的纳米氧化锌粒子相比,生物法合成的纳米氧化锌固定效果最好,固定化酶的酶活收率分别比普通氧化锌和传统纳米氧化锌提高114.2%和20.5%。论文还对该生物纳米固定化酶的pH和热稳定性以及重复使用性能进行了测定,结果表明酶固定化后稳定性明显提高,而且具有较好的重复使用性能。     

硫化铂族金属加氢催化剂的研究进展

硫化铂族金属催化剂为可提高有机液相加氢反应选择性的高效催化剂,能提高含羰基、羟基和卤素等官能团化合物催化加氢反应的选择性,应用广泛。综述了国内外负载型Pt和Pd等硫化贵金属催化剂的制备方法,包括采用H_2S和Na_2S无机硫化以及Ph_2S和DMSO(二甲基亚砜)等有机硫化剂进行硫化;综述了Pt和Pd硫化贵金属催化剂在有机液相催化加氢体系中的应用;并对硫化Pt族金属催化剂的硫化机理和催化机理进行探讨,展望了硫化贵金属催化剂的应用前景。     

Hydrodeoxygenation of guaiacol on noble metal catalysts

Hydrodeoxygenation (HDO) performed at high temperatures and pressures is one alternative for upgrading of pyrolysis oils from biomass. Studies on zirconia-supported mono- and bimetallic noble metal (Rh, Pd, Pt) catalysts showed these catalysts to be active and selective in the hydrogenation of guaiacol (GUA) at 100 °C and in the HDO of GUA at 300 °C. GUA was used as model compound for wood-based pyrolysis oil. At the temperatures tested, the performance of the noble metal catalysts, especially the Rh-containing catalysts was similar or better than that of the conventional sulfided CoMo/Al₂O₃ catalyst. The carbon deposition on the noble metal catalysts was lower than that on the sulfided CoMo/Al₂O₃ catalyst. The performance of the Rh-containing catalysts in the reactions of GUA at the tested conditions demonstrates their potential in the upgrading of wood-based pyrolysis oils.     

负载贵金属催化剂在挥发性有机物氧化反应中的应用

挥发性有机物(VOCs)是大气污染的主要来源,危害人体健康。催化氧化法是消除挥发性有机物的有效手段,其核心是高效催化剂,新型、高活性、高稳定性催化剂的研发具有重要意义。简要综述近年来负载Au、Pd和Pt贵金属催化剂对VOCs氧化消除的催化性能,分析VOCs氧化在典型催化剂表面形成的活性物种及其对催化活性的影响,并展望VOCs催化氧化的未来发展趋势。     

Dibenzothiophene hydrodesulfurization by noble metal supported catalysts

The hydrodesulfurization of dibenzothiophene (DBT) is investigated at 240°C, under one atmosphere pressure of H₂ + DBT, in a DBT conversion range giving rise to a H₂S concentration between 30 and 200 ppm. The turnover number (TN) of platinum slightly decreases as the dispersion of platinum (Ptins) to Pt ratio = D (Pt)) increases from 0.01 to 0.7, whatever support (α-Al₂0₃, SiO₂, chlorinated γ-Al₂O₃, SiO₂-Al₂O₃, montmorillonite) was used. Furthermore, the TN is much lower for highly dispersed Pt/γ-Al₂O₃-C1 (D(Pt) = 0.9; ø (Pt) = 1.0 nm). Pt/TiO₂ (D(Pt) = 0.06 or D(Pt) = 0.34) reduced or re-reduced at 240°C has a higher TN than the preceding catalysts. Reduction or re-reduction of Pt/TiO₂, at 500°C results in only a relatively small decrease in the catalytic activity, in spite of the appearance of a strong metal-support interaction observed by several workers. For different supported metals on Al₂O₃, the TN follows the sequence: Pt > Ir > Ru > Re. Alloying Ir or Ru (25 to 30 at %) with Platinum results in a relatively small decrease in the TN (per one (Pt_s + Ir_s or Ru_s ) atom).The activity, per unit weight of catalyst, of an industrial Co-Mo/γ-Al₂O₃ sulfided catalyst (HR 306) is equivalent to that of 1 % Pt/γ-Al₃0₃ (D(Pt) = 0.7). The present platinum supported catalysts have a very low selectivity in hydrogenation (production of phenylcyclohexane, PCH < 1 %), except when supported by silica, SiO₂-Al₂O₃ or montmorillonite; the Co-Mo/γ-Al₂0₃ catalyst has a selectivity which is intermediate between Pt/γ-Al₂O₃ and Pt/SiO₂-Al₂O₃ or montmorillonite. The deactivation (decrease in activity versus the time en-stream) is lower for Co-Moγ-Al₃0₃ than for Pt/γ-Al₃O₃, but the addition of Ge to Pt/γ-Al₂O₃ gives rise to a more stable catalyst.     

Hydrotreatment of jatropha oil over noble metal catalysts

Jatropha oil is a promising nonedible feedstock for producing renewable diesel. In this work, the hydrotreatment processing of jatropha oil was investigated. Instead of using conventional alumina-supported Co–Mo, Ni–Mo, and Ni–W catalysts that need sulfidation pretreatment, noble metals such as Pd and Ru were chosen. Trials were performed in an isothermal trickle-bed reactor and the reaction conditions were as follows: temperature 603–663?K, weight hourly space velocity (WHSV) 1 to 4/h, pressure 1.5–3?MPa, and H₂/oil ratio 200–800 (v/v). Yield of n-C₁₅ to n-C₁₈ hydrocarbons was maximized (70.3 and 43.8% for Pd/Al₂O₃ and Ru/Al₂O₃, respectively) at the following conditions: T?=?663 K, WHSV?=?2/h, P?=?3?MPa, and H₂/oil ratio?=?600 (v/v). Since Ru favored cracking reactions to a larger extent than Pd, the yield of C₁₅ to C₁₈ hydrocarbons over Ru/Al₂O₃ was lowered. Using simple first-order plots for oil conversion, activation energies for the hydrotreating process over Pd/Al₂O₃ and Ru/Al₂O₃ were found and they were equal to 109 and 121?kJ/mol, correspondingly.