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1.
Active carbon supported copper oxides were used in NO reduction. The conversions of NO reduction depends strongly on surface oxygen-containing groups on the active carbons, among them the carboxyls and lactones favored remarkably the NO reduction. However, hydrochloric acid treatment led to the decomposition of the carboxyls and lactones on C2 and C3, decreasing their reactivities for NO reduction. Concentrated HNO3 treatment of active carbon produced higher conversions of NO reduction at relatively low temperatures due to the marked increase in the amounts of the carboxyls and lactones. 相似文献
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Ferenc Ungváry 《Coordination chemistry reviews》1998,170(1):245-281
Hydroformylation in homogeneous and heterogeneous systems and hydroformylation related reactions of carbon monoxide are reviewed. 相似文献
3.
TiO2负载型催化剂及光催化还原CO2反应的表面光电压谱研究 总被引:5,自引:0,他引:5
半导体TiO2作为光催化剂,已被广泛应用于光催化废水处理及光催化储能[1,2]等方面的研究.人们不断开发高活性的新型光催化剂并对其反应机理进行了探索性研究[3],希望通过表面负载Pd、Ru、Pt或Rh等贵金属的小岛式颗粒以传递光生电子(或光生空穴). 相似文献
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活性炭酸处理对CuO/C催化剂上NO还原反应的影响 总被引:3,自引:0,他引:3
4种国产活性炭被用于NO还原反应,其中,山楂核炭和山桃核炭具有较高的NO还原转化率。实验发现,表面含氧基团-COO-对活性炭自身的还原性和对NO的还原活性有很重要的影响。对表面富-COO-基团的活性炭,稀盐酸处理使表面-COO-显著分解。 相似文献
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1870年,Royer使用Zn电极将CO2还原为HCOOH。近年来,人们对CO2在几十种金属电极上的电化学还原进行了深入的研究。但普遍存在的问题是CO2在金属电极上还原的过电位较大,导致耗电较多。 相似文献
6.
活性碳纤维对银离子还原吸附能力的改进 总被引:8,自引:0,他引:8
活性碳纤维不仅对有机物有高的吸附容量,对贵金属离子也具有强的还原吸附能力,可将Pd(Ⅱ),Ag(Ⅰ),Au(Ⅲ)等离子还原为金属单质。因而可用于提取矿液或加收废液中的贵金属。由此,提高或改善贵金属在活性碳纤维上的还原吸附容量或分布形成,显得非常重要。本文研究了活性碳纤维制备条件、表面氧化改性、以有负载有机物等对活性碳纤维还原能力的影响。结果表明,(1)制备条件对剑麻基活性碳纤维的还原能力有很大的影响。用H3PO4或ZnCl2活化的活性碳纤维对银离子具有更高的还原吸附容量,分别可达250和700mg/g,约为水蒸汽活化剑麻基活性碳纤维对银离子还原吸附容量的2倍和5倍。(2)过氧化氢、高锰酸钾、或硝酸等无机氧化剂对活性碳纤维进行表面改性,也能提高活性碳纤维的还原能力。结果表明,虽然改性活性碳纤维的比表面积和孔体积下降10-20%左右,但基表面含氧量及含氧基团的种类发生了改变。这些改性活性碳纤维对Ag(NH3)2^ 的还原吸附量大幅度提高,可达550mg/g以上。推断表面改性在活性碳纤维表面创造了更多有利于碱性条件下发生氧化还原的活性点。(3)在活性碳纤维表面负载适当的有机物如亚甲基蓝、苯胺或对硝基苯酚,也能显著提高活性碳纤维对Ag(NH3)2^ 的还原吸附能力。 相似文献
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CHEN Shuixia XU Ruimei ZHANG Xiaoping ZENG Hanmin Materials Science Institute Zhongshan University Guangzhou China . Department of Environmental Science Engineering South China University of Technology Guangzhou China 《Chinese Journal of Reactive Polymers》2002,(2)
1. INTRODUCTION The discharge of effluent containing precious metal ions, which comes from electroplating, mining, smelting, and other industries, not only contaminate the environment where people live, but also cause the waste of natural resources. From… 相似文献
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The reduction adsorption of silver diamminonitrate on different kinds of activated carbonfibers (ACF) has been studied in this paper. The effect of different parameters, including adsorptiontemperature, concentrations of activation agents, and activation time on the silver adsorptioncapacities of activated carbon fibers has been investigated The results show that higher temperaturein which the silver complex interacts with ACF. or higher concentration of activation agent, will makehigher reduction adsorption capacities of ACFs. More over, ACFs activated with phosphoric acidhave higher reduction capacities than those activated with zinc chloride or steam. 相似文献
9.
化学蚀刻玻璃球,表面产生纳米孔缝,再通过溶剂热法在孔缝内制备了非晶态有机钛聚合物。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、电感耦合等离子体原子发射光谱(ICP-AES)、紫外-可见漫反射光谱(UV-Vis)、荧光光谱(PL)、有机元素分析(OEA)、紫外光电子能谱(UPS)和傅里叶变换红外光谱(FT-IR)等表征了材料的结构及光电性能。结果表明,负载的非晶态有机钛聚合物对可见光有明显的吸收,且荧光强度较NH2-MIL-125(Ti)大幅度降低,光生电子-空穴对更加稳定。玻璃球负载的非晶态有机钛聚合物为催化剂,300 W氙灯为光源催化还原CO2,反应4 h后,甲醇的产量达941.6 μmol,相应的转换频率(TOF)值为46.4 h-1。使用具有相同有机配体及金属离子的NH2-MIL-125(Ti)及P25为对比催化剂,在相同的光催化条件下,其相应的TOF分别为0.28和0.019 h-1。催化剂热处理实验表明玻璃球载体对有机钛聚合物的化学稳定性有明显的保护作用,经过300 ℃处理,负载的有机钛聚合物光催化性能仍然稳定,而NH2-MIL-125(Ti)的光催化活性衰减了54%,这是由于其化学结构及晶体结构被破坏。 相似文献
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Reduction kinetics of magnesia with carbon powder was studied using the thermal gravimetric technic in the temperature range of 1743–1883 K. The reduction ratio was determined as a function of time. The effects of compact-forming pressure, composition, partial pressure of CO, sample height, and temperature on reduction ratio were investigated. Experimental results revealed that the gas diffusion including Mg vapor, CO and CO2 through the porous medium was the rate-determining step of the overall reduction process. Activation energy of the gas diffusion was estimated to be about 30.59 kJ mol−1. 相似文献
11.
As one of the most appealing and attractive technologies, photocatalysis is widely used as a promising method to circumvent the environmental and energy problems. Due to its chemical stability and unique physicochemical, graphitic carbon nitride (g-C3N4) has become research hotspots in the community. However, g-C3N4 photocatalyst still suffers from many problems, resulting in unsatisfactory photocatalytic activity such as low specific surface area, high charge recombination and insufficient visible light utilization. Since 2009, g-C3N4-based heterostructures have attracted the attention of scientists worldwide for their greatly enhanced photocatalytic performance. Overall, this review summarizes the recent advances of g-C3N4-based nanocomposites modified with transition metal sulfide (TMS), including (1) preparation of pristine g-C3N4, (2) modification strategies of g-C3N4, (3) design principles of TMS-modified g-C3N4 heterostructured photocatalysts, and (4) applications in energy conversion. What is more, the characteristics and transfer mechanisms of each classification of the metal sulfide heterojunction system will be critically reviewed, spanning from the following categories: (1) Type I heterojunction, (2) Type II heterojunction, (3) p-n heterojunction, (4) Schottky junction and (5) Z-scheme heterojunction. Apart from that, the application of g-C3N4-based heterostructured photocatalysts in H2 evolution, CO2 reduction, N2 fixation and pollutant degradation will also be systematically presented. Last but not least, this review will conclude with invigorating perspectives, limitations and prospects for further advancing g-C3N4-based heterostructured photocatalysts toward practical benefits for a sustainable future. 相似文献
12.
采用XRD、BET、TPR手段,研究了焙烧和还原温度对超细CuO-ZnO-SiO2催化剂的性质及其CO2加氢反应催化活性的影响.胶体在573-773K范围内焙烧生成CuO、Cu2O、ZnO晶相,随着焙烧温度继续升高,CuO和ZnO晶粒逐渐变大,但催化剂的比表面积和孔容变化很小.在973K焙烧后出现Zn2SiO4晶相,使催化剂比表积和孔容变小,导致催化剂活性降低.焙烧温度对催化剂活性的影响大于对CO2加氢产物分布的影响.在548-648K范围内,催化剂还原温度对其催化活性影响不大.703K高温还原后,可能由于Cu0晶粒的出现,使得催化剂的活性下降.TPR研究结果进一步表明,焙烧温度影响CuO同ZnO、SiO2之间的相互作用和催化剂的还原行为. 相似文献
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1 Introduction
Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry. 相似文献
Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry. 相似文献
17.
Ferenc Ungváry 《Coordination chemistry reviews》2005,249(24):2946-2961
Hydroformylation in homogeneous and heterogeneous systems, and hydroformylation related reactions of carbon monoxide reported in 2004 are reviewed. 相似文献
18.
实验证明,第1步还原E_(1/2)=-0.96V(文中所有的电位均相对于Ag参比电极);第2步E_(1/2)=-1.56V。该体系的特征是伴随的均相反应具有较低的速率常数,在一般的循环伏安法扫描时间内很难觉察到均相反应的进行。若采取时间窗较长的实验方法,将有利于观察伴随均相反应的动力学效应。恒电位库仑法时间域约为100~ 相似文献
19.
As a strong reducing radical, carbon dioxide anion radical(CO2·-) can be generated by initiating sulfate radical(SO4·-) in the presence of formate anions(FA) for Cr(VI) reduction. Moreover, activated carbon(AC)-catalyzed persulfate(PS) oxidation is an economically justifiable, environmentally friendly, and easy-to-scale-up method to produce SO4·-. The complete removal of Cr(VI) was achieved within 280 min for an initial Cr(VI) concentration of 50 mg/L under the optional condition of c(AC)=1 g/L, [PS]0=10 mmol/L, [FA]0=10 mmol/L, T=30℃, and unadjusted pH. When the molar ratio of FA to PS was greater than or equal to 1, the system maintained a strong reduction state. The mechanism investigation confirmed that FA was converted to carboxyl anion radical(CO2·-) as the predominant radical for Cr(VI) reduction. This novel system may offer a potential platform technology for Cr(VI) wastewater treatment. 相似文献
20.
Jerzy Zakrzewski 《Monatshefte für Chemie / Chemical Monthly》1990,121(10):803-808
Summary The mild reduction of the nitroxides1 a–j to the corresponding sterically hindered amines2 a–j by means of ethyl mercaptane is reported. The reaction mixtures of1 a, b, g were analyzed by glc/ms.
Die Reaktion von Nitroxiden mit Ethylmercaptan: Eine milde Methode für die Umsetzung von Nitroxiden zu den entsprechenden Aminen
Zusammenfassung Es wird über die milde Reduktion der Nitroxide1 a–j zu den entsprechenden sterisch gehinderten Aminen2 a–j mittels Ethylmerkaptan berichtet. Die Reaktionsmischungen von1 a, b, g wurden mittels GLC/MS analysiert.相似文献