Journal of the Chemical Society, Faraday Transactions最新文献_第5页

Spin-coupled description of fluorocyclophosphazenes (NPF2)3, (NPF2)4, (NPF2)5 氟环磷腈(NPF2)3、(NPF2)4、(NPF2)5的自旋耦合描述

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A708127H

M. Raimondi, M. Sironi, J. Gerratt, D. L. Cooper, P. Karadakov

引用次数: 1

H–D Exchange between methane and deuteriated potassium amide supported on alumina 氧化铝负载的甲烷与氘化钾酰胺之间的H-D交换

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A706059I

H. Handa, T. Baba, Y. Ono

引用次数: 11

A reduced model for complex oscillatory responses in the mesosphere 中间层复杂振荡响应的简化模型

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A804150D

Barry R. Johnson, S. Scott, M. Tinsley

引用次数: 9

XAFS study of zirconia-supported copper catalysts for the NO–CO reaction: Deactivation, rejuvenation and stabilization of Cu species 氧化锆负载铜催化剂在NO-CO反应中的XAFS研究:Cu的失活、再生和稳定

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A807152G

Y. Okamoto, T. Kubota, Hideki Gotoh, Yoshiharu Ohto, H. Aritani, Tsunehiro Tanaka, S. Yoshida

{"title":"XAFS study of zirconia-supported copper catalysts for the NO–CO reaction: Deactivation, rejuvenation and stabilization of Cu species","authors":"Y. Okamoto, T. Kubota, Hideki Gotoh, Yoshiharu Ohto, H. Aritani, Tsunehiro Tanaka, S. Yoshida","doi":"10.1039/A807152G","DOIUrl":"https://doi.org/10.1039/A807152G","url":null,"abstract":"A Cu/ZrO2 (1 wt.% Cu) catalyst shows high activity for the NO–CO reaction, even at low temperature (100–200 °C). However, the low-temperature activity is easily lost during prolonged reaction at 250 °C. The activity of the deactivated Cu/ZrO2 catalyst is completely restored by NO treatment (1% in He) at >250 °C or O2 treatment (5% in He) at 500 °C. The addition of iron (2 wt.%) to Cu/ZrO2 causes not only a dramatic increase in the low-temperature activity but also high stability against deactivation. An X-ray absorption fine structure (XAFS) study has been conducted to reveal the local structure and chemical state of the Cu species in Cu/ZrO2 and Cu–Fe/ZrO2 during the reaction and rejuvenation. X-ray absorption near-edge structure (XANES) spectra and, in particular, their first derivatives are shown to be very effective for characterization of the Cu species. It is revealed that the deactivation of Cu/ZrO2 is a consequence of reduction and sintering of highly dispersed Cu+ species, derived from Cu2+(Oct) species in an octahedral symmetry, to Cu metal particles. The Cu metal particles in a deactivated Cu/ZrO2 catalyst are transformed into the original Cu2+(Oct) species by the NO treatment at 250 °C via highly dispersed Cu+ species. On the other hand, O2 treatments bring about successive formation of Cu2O at 150 °C and CuO at 250 °C. The Cu2+(Oct) species are reformed at >400 °C. The XAFS study of Cu–Fe/ZrO2 suggests that the high stability of highly dispersed Cu+ species is a consequence of direct interaction of Cu species with iron oxide clusters. On the basis of kinetics and XAFS results, the catalytic synergies between Cu and Fe are inferred to be two-fold: stabilization of highly dispersed and catalytically active Cu+ species during the reaction and simultaneous participation of both Cu and Fe in the reaction.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86429113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 48

Ceria lattice oxygen ion substitution by Cl− during the reduction of Rh(Cl)/CeO2 catalysts. Formation and stability of CeOCl Rh(Cl)/CeO2催化剂还原过程中铈晶格氧离子被Cl−取代。CeOCl的形成和稳定性

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A805625K

F. Fajardie, ois Tempere, J. Manoli, G. Djéga-Mariadassou, G. Blanchard

{"title":"Ceria lattice oxygen ion substitution by Cl− during the reduction of Rh(Cl)/CeO2 catalysts. Formation and stability of CeOCl","authors":"F. Fajardie, ois Tempere, J. Manoli, G. Djéga-Mariadassou, G. Blanchard","doi":"10.1039/A805625K","DOIUrl":"https://doi.org/10.1039/A805625K","url":null,"abstract":"Rh/CeO2 systems prepared by anionic exchange of anionic rhodium chloro complexes contain significant amounts of chloride. They are referred to as Rh(Cl)/CeO2 catalysts. Reduction at 1173 K does not decrease the chloride content of these catalysts but calcination in air at the same temperature leads to total elimination of Cl− ions. A temperature-programmed reduction (TPR) study evidenced the promoting effect of rhodium on the reducibility of CeO2 and showed that quasi-stoichiometric incorporation of chloride ions into ceria occurred at a relatively low reduction temperature (323–523 K), simultaneously with rhodium reduction to Rh(0). It is proposed that chloride incorporation occurs through the migration of surface Cl− ions into oxygen vacancies of CeO2 resulting from the reduction of surface oxygen by dissociated hydrogen spilled over from Rh(0) to the CeO2 surface. The incorporation of chloride was found to inhibit progressively the process of hydrogen spillover below 773 K. No CeOCl phase could be detected at the corresponding low reduction temperatures. However, catalysts containing higher chloride loadings were used to show that CeOCl was formed at higher reduction temperatures than that necessary for chloride incorporation into CeO2, supporting the hypothesis that Cl− ions are incorporated into the ceria lattice at low temperatures. CeOCl was found to be unstable in air but the phase could be restored upon additional reducing treatment, thus showing the reversibility of the Cl− ion migration into the oxygen vacancies of ceria.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83989153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 56

Excess proton hydrate structures with large proton polarizability in the channel of trioxaalkyl phosphate 三氧烷基磷酸盐通道中具有大极化率的多余质子水合物结构

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A708928G

B. Brzeziński, Bartosz Różalski, G. Schroeder, F. Bartl, G. Zundel

引用次数: 24

The deconvolution of nucleation and growth rates from electrochemical current–time transients 电化学电流时间瞬态的成核和生长速率的反卷积

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A806348F

R. Deutscher, S. Fletcher

{"title":"The deconvolution of nucleation and growth rates from electrochemical current–time transients","authors":"R. Deutscher, S. Fletcher","doi":"10.1039/A806348F","DOIUrl":"https://doi.org/10.1039/A806348F","url":null,"abstract":"Two new algorithms have been developed for the deconvolution of nucleation and growth rates from electrochemical current–time transients. The first is called Bootstrap, and is based on the method of successive approximations. The second is called Simplefit, and utilizes a curve-fitting procedure based on the simplex method. Both are able to provide numerical estimates of the number of crystals as a function of time, to better than 2% accuracy, in the presence of significant noise. The advantage of the algorithms is that they produce accurate output under conditions where standard methods fail. In particular, the number of crystals versus time can be determined even when crystal growth switches from interfacial control to diffusion control on the timescale of measurements. The efficacy of the algorithms is demonstrated on two real systems, namely the nucleation of zinc on carbon, and the nucleation of lead on carbon. In both cases non-steady states of nucleation are readily observed in the presence of time-varying crystal growth rates. In addition, a new phenomenon is seen for which the name ''nucleation persistence'' is suggested. This is the transient continuation of a high rate of nucleation after a rapid decrease in overpotential. The phenomenon is attributed to the slow readjustment of the size distribution of microscopic nuclei on the electrode surface. Interestingly, the existence of nucleation persistence invalidates the double potential step technique, which has previously been regarded as the standard method for observing electrochemical nucleation and growth. Finally, the mathematical theory of nucleation persistence is briefly sketched.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90353463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 20

Comprehensive structural and spectroscopic study of intrazeolite anchoring of ruthenium carbonyl clusters 羰基钌团簇在沸石内锚定的结构和光谱综合研究

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A707777G

G. Shen, A. Liu, M. Ichikawa

{"title":"Comprehensive structural and spectroscopic study of intrazeolite anchoring of ruthenium carbonyl clusters","authors":"G. Shen, A. Liu, M. Ichikawa","doi":"10.1039/A707777G","DOIUrl":"https://doi.org/10.1039/A707777G","url":null,"abstract":"[Ru3(CO)12] guests in Na56Y were thermally activated from 298 to 363 K, in a hydrogen atmosphere, generating intrazeolitic [H4Ru4(CO)12]. Hexaammineruthenium(III) complexes in Na56X have been thermally activated progressively from 298 to 393 K, in CO and H2 atmospheres. The generation process is via conversion of the intermediate [Ru(NH3)5(CO)]2+, RuI(CO)3 to [Ru6(CO)18]2−. The characterization of the structure and properties of these samples used a multi-analytical approach based on FTIR, UV-VIS, EXAFS spectroscopies and CO and H2 gas chemisorption. The research encompassed several key points as follows: (i) kinetics of the intrazeolitic diffusion of [Ru3(CO)12] clusters; (ii) oxidation fragmentation under O2 atmosphere and reductive regeneration under CO and H2 chemisorption with temperature-programmed heating for the intrazeolite anchoring of [Ru6(CO)18]2−; (iii) internal vs. external confinement of ruthenium carbonyl clusters; (iv) intrazeolite anchoring of ruthenium carbonyl clusters shows a strong reaction with the extraframework Na+ α-cage cations, through involvement of the oxygen end of the bridging or equatorial terminal carbonyl ligands; (v) comparison of orbitally degenerate ground-state for free Ru carbonyl clusters vs. the intrazeolitic anchoring site provides a theoretical indication of the symmetry distortion.These multi-analytical spectroscopic methods should motivate both new and established scientists to study further the anchoring of metal carbonyl clusters with other types of zeolite (such as ZSM-5 or MCM-41). Faujasite mediated synthesis of metal carbonyl clusters can provide routes to compounds which are not accessible by conventional solution techniques. Further, higher yield clusters, as well as a better understanding of the nucleation process of cluster formation and of the resulting chemical properties can be expected.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79589508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

13 C NMR estimation of preferential solvation of lithium ions in non-aqueous mixed solvents 锂离子在非水混合溶剂中优先溶剂化的13c核磁共振估计

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A807010E

K. Matsubara, Rie Kaneuchi, Noriko Maekita

引用次数: 44

Laser flash photolysis studies of the interaction of Rose Bengal with an iron arene complex 激光闪光光解孟加拉玫瑰与铁芳烃配合物相互作用的研究

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A801981I

D. Burget, J. Fouassier

引用次数: 28