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Reactions of NO in a Positive Streamer Corona Plasma 总被引:2,自引:0,他引:2
Tas Marnix A. van Hardeveld R. van Veldhuizen E. M. 《Plasma Chemistry and Plasma Processing》1997,17(4):371-391
The reaction of NO in a streamer corona plasma is studied systematically as a function of the composition of the gas mixture, the initial concentration of NO, and the discharge repetition rate. The experimental results show that the reactions of NO depend strongly on the composition of the gas mixture. Reduction is observed in the absence of oxidants such as oxygen and water, but at very high energy cost (>200 eV/NO). In the presence of both these oxidants, more than 90% of the NO conversion is oxidation. The lowest energy costs, 24 eV/NO for He mixtures and 45 eV/NO for N
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mixtures, are obtained at water and oxygen concentration above 3% and at low discharge repetition rates (<10 Hz). Chemical kinetics calculations of the production of radicals in the plasma show a good agreement with the value derived from the experiments. 相似文献
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Tetsu Hanmura Masahiko Ichihashi Ryuji Okawa Tamotsu Kondow 《International journal of mass spectrometry》2009,280(1-3):184
Reactions of NO molecules on cobalt cluster ions were studied in a beam-gas geometry by using a tandem mass spectrometer. Single-particle collision reactions of ComNO+ (m = 3–10) with NO were found to proceed in such a manner that NO decomposition dominates at m = 4–6 with the maximum reaction cross section at m = 5 and chemisorption dominates in m ≥ 7. On the other hand, in two-particle collision reactions of Con+ (n = 2–10) with NO, NO decomposition at n ≥ 5 and chemisorption of two NO molecules with Co atoms loss at n ≥ 8 were found to proceed. These results indicate that the size-dependency of the multiple collision reactions originates from secondary attacking of an NO molecule to primary products of the initial single collision reactions. The DFT calculation supports the scheme that both the decomposition and chemisorption of two-particle collision reactions proceed via a common intermediate, ComN2O2+, in which the two NO molecules are dissociatively chemisorbed on the cobalt cluster ion, and the size-dependency of the two-particle collision reactions is explained in terms of the structure of this reaction intermediate. 相似文献
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综述了本研究小组利用量子化学簇模型方法研究金属氧化物表面化学吸附和反应的工作.提出了选簇的三个原则,即电中性原则、化学配比原则和配位原则.发现在符合前两个原则的基础上,一个具有最饱和配位、或最少悬空键的簇往往是一个用于化学吸附研究的好的簇模型.与此同时,探讨了如何恰当地考虑大块固体本底的长程影响,提出了用球电荷模拟簇模型的环境、环境与簇体进行电荷自洽的SPC簇模型方法.利用该模型研究了一系列具有催化背景的重要体系,包括H2/ZnO、O/MgO、NO/MgO、N2O/MgO、N2O/Li/MgO、CO/MgO、CO/NiO等. 相似文献
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Vandna Luthra Keith F.E. Pratt Robert G. Palgrave David E. Williams R.P. Tandon Ivan P. Parkin 《Polyhedron》2010
As part of a systematic study of mechanisms of response of semiconducting oxides as trace gas sensors, we have explored the behaviour of iron–titanium oxide solid solutions Fe2−xTixO3 (x = 0.1–1.4). The materials were single-phase for x = 0.1 with increasing proportions of a pseudobrookite second phase at higher degree of substitution. Unmodified, pure iron oxide does not show sensitivity to CO. A significant signal was developed for x = 0.1, that then diminished with increasing x and was lost for x = 1.4. Three effects have been deduced important for the gas response: significant surface segregation of Ti at low Ti content; grain growth inhibition and agglomeration into more massive, non-porous lumps as Ti content increased; and the appearance of a band-gap state associated with Fe(II) at higher Ti content. The effects of microstructure change have been analyzed by fitting the data to a simple 2-resistor model of gas-insensitive ‘grains’ in series with gas-sensitive ‘grain boundaries’. A Mars–van Krevelen type model for the response is presented, based on reactions at surface-segregated defect clusters, to develop and remove electrically-active surface trap states. 相似文献
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Hydrogenation reaction is one of the pillars of the chemical industry for the synthesis of drugs and fine chemicals. To achieve high catalytic performance, it is still highly desirable for constructing novel supported metal catalysts. Different from conventional supports like metal oxides, zeolites and carbon materials, metal-organic frameworks(MOFs) as the emerging porous materials have Hexhibited great potential to host metal nanoparticles (NPs) for achieving hydrogenation reactions with high catalytic efficiency, due to their unique porous structures. Recently, many progresses have been made, and thus, it is necessary to summarize the recent progresses on confining metal NPs inside MOFs for hydrogenation reactions. In this review, we first introduced the general synthesis methods for confining noble metal NPs inside MOFs. Then, the applications of noble metal NPs/MOFs catalysts in hydrogenation reactions were summarized, and the synergistic catalytic performances among noble metal NPs, metal nodes, functional groups, and pore channels in MOFs were illustrated. Subsequently, the hydrogen spillover effect involved in the hydrogenation reactions was discussed. Finally, we provide an outlook on the future research directions and challenges of confining noble metal NPs inside MOFs for hydrogenation reactions. 相似文献
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分子筛笼内铂羰基簇合物在CO+NO反应中的催化研究 总被引:1,自引:1,他引:1
研究了NaY分子筛超笼内包容的Pt羰基簇合物催化剂在CO+NO反应中的催化性能。「Pt12(CO)24」^2-/NaY和「Pt9(CO)13」^2-/NaY在此反应中表现出比较高的活性。N2O被认为是CO+NO反应的中间产物,同时笼内羰基簇合物还表现了比SiO2负载的簇合物好的热稳定性,动力学研究表明,在「Pt12(CO)24」^2-/NaY上,NO被还原和N2O生成的反应级数,相对于CO分压为小 相似文献
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用高温气-固相置换法对ZK-4、NaA和NaHS3种沸石进行铝化。组成分析、尾气分析、X射线衍射、晶体形貌分析、红外光谱和29Si高分辨魔角固体核磁结果表明,3种低硅铝比沸石铝化后骨架可能存在Al-O-Al键。 相似文献
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Functionalizing Single Crystals: Incorporation of Nanoparticles Inside Gel‐Grown Calcite Crystals
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Yujing Liu Wentao Yuan Ye Shi Xiaoqiang Chen Prof. Yong Wang Prof. Hongzheng Chen Prof. Hanying Li 《Angewandte Chemie (International ed. in English)》2014,53(16):4127-4131
Synthetic single crystals are usually homogeneous solids. Biogenic single crystals, however, can incorporate biomacromolecules and become inhomogeneous solids so that their properties are also extrinsically regulated by the incorporated materials. The discrepancy between the properties of synthetic and biogenic single crystals leads to the idea to modify the internal structure of synthetic crystals to achieve nonintrinsic properties by incorporation of foreign material. Intrinsically colorless and diamagnetic calcite single crystals are turned into colored and paramagnetic solids, through incorporation of Au and Fe3O4 nanoparticles without significantly disrupting the crystalline lattice of calcite. The crystals incorporate the nanoparticles and gel fibers when grown in agarose gel media containing the nanoparticles, whereas the solution‐grown crystals do not. As such, our work extends the long‐history gel method for crystallization into a platform to functionalize single‐crystalline materials. 相似文献
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Dr. Yanan Tang Dr. Weiguang Chen Dr. Gao Zhao Dr. Da Teng Dr. Yingqi Cui Dr. Zhaohan Li Dr. Zhen Feng Prof. Xianqi Dai 《Chemphyschem》2021,22(6):606-618
Noble metal single-atom catalysts (NM-SACs) anchored at novel graphene-like supports has attracted enormous interests. Gas sensitivity, catalytic activity, and d-band centers of single NM (Pt and Pd) atoms at graphenylene (graphenylene-NM) are investigated using first-principle calculations. The adsorption geometries of gas reactants on graphenylene-NM sheets are analyzed. It is found that the adsorption energies of reactant species on graphenylene-Pt are larger than those on graphenylene-Pd, because the d-band center of the Pt atom is closeser to the Fermi level. The NO and CO oxidation reactions on graphenylene-NM are investigated via four catalytic mechanisms, including Langmuir-Hinshelwood (LH), Eley-Rideal (ER), New ER (NER), and termolecular ER (TER). The results show that the NO and CO oxidations via LH and TER mechanisms can occur owing to the relatively small energy barriers. Moreover, the interaction of 2NO+2CO via ER mechanism is the energetically more favorable reaction. Although the NO oxidation via the NER mechanism has rather low energy barriers, the reaction is unlikely to occur due to the low adsorption energy of O2 compared with CO and NO. This research may provide guidance for exploring the catalytic performance of SACs on graphene-like materials to remove toxic gas molecules. 相似文献
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G. N. Schrauzer 《Angewandte Chemie (International ed. in English)》1975,14(8):514-522
The development of biologically relevant model systems of nitrogenase permitted the simulation of virtually all known reactions of the nitrogen reducing enzymes under nonenzymatic conditions. On the basis of these experiments, a mechanism of biological nitrogen fixation is formulated which is in accord with the available enzymological evidence. The key reactions of the substrates of nitrogenase occur at a molybdenum active site. The non-heme iron, which is bound to sulfur and protein-S? groups, mediates the transport of electrons to the molybdenum active site but does not participate directly in the reduction of the substrates. ATP is required for the acceleration of the reduction and activation of the molybdenum site and is hydrolyzed to ADP and inorganic phosphate. Diimine and hydrazine were detected as intermediates in the reduction of molecular nitrogen under nonenzymatic conditions. 相似文献
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在 CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)+ZPE 水平上对反应C2H+NO2 进行了计算, 建立了反应势能面并得到了3种产物. 利用RRKM理论估算了反应的总速率和分支比. 总速率为1.427×10-12×T0.556×exp(190.547/T) cm3*molecule-1*s-1, 其中主要产物P1(HCCO+NO)比例大于96%, 次要产物P2(HCNO+CO)和P3(HCN+CO2)小于4%. 相似文献
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随着绿色化学的逐渐推广,碳材料作为最有前途的绿色无金属催化剂而备受关注。通过对石墨烯引入杂原子进行化学掺杂是目前最常用于改良碳材料催化活性的有效方法。从结构上看,掺杂石墨烯内特定活性物种在催化过程中起到活性位点的作用,且催化剂的催化活性随活性位点含量增加而增强。且其内部活性位点含量可通过改变制备方法中制备条件实现调控,这有助于开发具有高催化活性的掺杂石墨烯催化剂。本文综述了氮掺杂石墨烯和硼掺杂石墨烯内可作为活性位点的官能团,提出制备方法对活性位点含量的影响,并讨论了内部活性位点在氧化反应中的作用。最后对未来研究方向提出了建议和展望,为开发更高效掺杂石墨烯催化剂提供了思路。 相似文献
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Hui Zheng Ziwei Ma Yunxia Liu Yizhe Zhang Jinyu Ye Elke Debroye Longsheng Zhang Tianxi Liu Yi Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(1):e202316097
Electrocatalytic nitrogen oxidation reaction (NOR) offers an efficient and sustainable approach for conversion of widespread nitrogen (N2) into high-value-added nitrate (NO3−) under mild conditions, representing a promising alternative to the traditional approach that involves harsh Haber–Bosch and Ostwald oxidation processes. Unfortunately, due to the weak absorption/activation of N2 and the competitive oxygen evolution reaction, the kinetics of NOR process is extremely sluggish accompanied with low Faradaic efficiencies and NO3− yield rates. In this work, an oxygen-vacancy-enriched perovskite oxide with nonstoichiometric ratio of strontium and ruthenium (denoted as Sr0.9RuO3) was synthesized and explored as NOR electrocatalyst, which can exhibit a high Faradaic efficiency (38.6 %) with a high NO3− yield rate (17.9 μmol mg−1 h−1). The experimental results show that the amount of oxygen vacancies in Sr0.9RuO3 is greatly higher than that of SrRuO3, following the same trend as their NOR performance. Theoretical simulations unravel that the presence of oxygen vacancies in the Sr0.9RuO3 can render a decreased thermodynamic barrier toward the oxidation of *N2 to *N2OH at the rate-determining step, leading to its enhanced NOR performance. 相似文献
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