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The mechanism of hydrogen abstraction by high valence transition metal oxo compounds

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Journal of Energy Chemistry 2016年第6期25卷 1045-1050页

作者： Gang Fu Ruming Yuan Huilin Wan Xin Xu Department of Chemistry State Key Laboratory for Physical Chemistry of Solid Surfaces College of Chemistry & Chemical Engineering Xiamen University Department of Chemistry MOE Laboratory for Computational Physical Science Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsFudan University

We present here a systematic theoretical study to explore the underlying mechanisms of the H abstraction reaction from methane. Various abstracting agents have been modeled, using oxygen radicals and a set of high valence metal oxo compounds. Our calculations demonstrate that although H abstraction from CH3-H by metal oxoes can be satisfactorily fitted into the Polanyi correlation on the basis of oxygen radicals, the mechanisms behind are significantly different. The frontier orbital analyses show that there are three electrons and three active orbitals (3e, 3o) involved in H abstraction by oxygen radicals; whereas an additional orbital of pi(M-O)* is involved in H abstraction by M = O, resulting in a (4e, 4o) interaction. In terms of valence bond state correlation diagram, we find that H abstraction by a metal oxo may benefit from the contribution of ionic resonance structures, which could compensate the penalty of opening the M-O pbond. We believe that these findings can help to design more effective catalysts for the activation of light alkanes. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B. V. and Science Press. All rights reserved.

关键词： C-H bond activation Polanyi relationship Oxygen radical Valence bond state correlation diagram DFT calculation

Synergetic effect of TeMo_5O_(16) and MoO_3 phases in MoTeO_x catalysts used for the partial oxidation of propylene

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Journal of Natural Gas Chemistry 2011年第3期20卷 249-255页

作者： Yiming He Ying Wu Weizheng Weng Huilin Wan Department of Materials Physics Zhejiang Normal University Jinhua 321004 Zhejiang China State Key Laboratory for Physical Chemistry of the Solid Surfaces Xiamen University Xiamen 361005 Fujian China Institute of Physical Chemistry Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces Zhejiang Normal University Jinhua 321004 Zhejiang China

Abstract A detailed study on the synergetic effect of TeMo 5 O 16 and MoO 3 phases in the MoTeO x catalysts for the partial oxidation of propylene to acrolein has been reported in this work. It was found that both propylene conversion and acrolein selectivity increased with the addition of MoO 3 to TeMo 5 O 16 . Based on the results of N 2 adsorption-desorption, XRD, XPS, in-situ XRD, O 2 -TPO, and 2-propanol decomposition reaction, the higher catalytic performance and synergetic effect could be attributed to the enhancement of acidity and the oxygen transfer from TeMo 5 O 16 to MoO 3 phase.

关键词： synergy TeMO5O16 MoO3 acidity oxygen transfer

Stress value in 2003 Dayao Ms6.1 earthquake source region

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Earthquake Science 2011年第4期24卷 343-350页

作者： Xiaofeng Xu Yongge wan Huilin Wang Earthquake Administration of Hainan Province Haikou 570203 China Institute of Disaster Prevention of Science and Technology Hebei 065201 China

The Ms6.2 Dayao, Yunnan, earthquake occurred on July 21, 2003, followed by a major Ms6.1 earthquake about 88 days later in the same region. Hypocenters of the two earthquakes are almost in the same place. Based on the P wave first motion polarities of the two aftershock sequences recorded by temporary stations, we have studied the stress field in the aftershock zone and obtained the two stress field directions in Dayao region using the new version of PKU_Grid^Test Software provided by Chunquan Yu. Assuming that the rotation of the stress field is caused by the second main shock, we estimated the crustal stress value in the focal region by using the stress value calculation method proposed by Yongge wan. The estimated maximum, intermediate and minimum principal stresses are 166.3 MPa, 158.7 MPa and 151 MPa, respectively, before the second main shock. The normal and shear stresses projected on the fault plane of the second main shock before it occurred are 157.3 MPa, 7.4 MPa, and are 158.8 MPa, 0.2 MPa after it occurred, respectively. The perturbed input parameters experiments attest the stability of the solution. The result shows that the preseismic shear stress is larger than the post-seismic one, and their difference corresponds to the stress drop approximately. The estimated compressive stress level is very high, but the differential stress is low. The result is helpful for friction coefficient estimation, plate motion simulation and related studies.

关键词： composite fault plane solution stress field stress magnitude 2003 Dayao twin earthquake

The origin of the site preference of H adsorption on Pd(100)

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Science China Chemistry 2015年第1期58卷 156-161页

作者： Lingyun Zhou Yun Zhao Zhening Chen Gang Fu Huilin Wan State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University

Spin-polarized density functional theory(DFT)calculations are carried out to determine the site preference of H adsorption on Pd(100)surface and subsurface.We carefully scrutinize the energy difference between different patterns at=0.50 ML and confirm the LEED observation that surface adsorption can form c(2×2)ordering structure.On the contrary,we disclose that p(2×1)structure become more favorable than c(2×2)for subsurface adsorption.These site preferences are rationalized via an analysis of the layer and orbital resolved density of states.Furthermore,we propose that the interstitial charge as a key factor determining the preferred H adsorbed site.

关键词：表面吸附偏好部位密度泛函理论起源自旋极化 LEED 钯

Active site of praseodymium orthovanadate catalyst in oxidative dehydrogenation of propane

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Chinese Science Bulletin 1998年第3期43卷 217-220页

作者： Weide Zhang Chaktong Au Huilin Wan Xiamen Univ Dept Chem Xiamen 361005 Peoples R China Xiamen Univ State Key Lab Phys Chem Solid Surface Xiamen 361005 Peoples R China Hong Kong Baptist Univ Dept Chem Hong Kong Hong Kong

The pure phase of praseodymium orthovanadate (PrVO\-4) has been prepared by the citrate method. The active site of PrVO\-4 was studied by ESR, NO_TPD, O\-2_TPD and 18 O\-2_isotope exchange methods. The results of ESR and NO_TPD confirmed the presence of V 4+ in the catalyst. 18 O\-2_isotope exchange was through a single exchange procedure. From the result of O\-2+TPD and the kinetic study of 18 O\-2_isotope exchange, one can reach a conclusion that the V 4+ species associated with oxygen vacancies are the site for O\-2 activation. The adsorbed O\-2 or O\+- are the active oxygen species in propane oxidative dehydrogenation.

关键词： praseodymium orthovanadate active site propane oxidative dehydrogenation catalyst.

In-Situ FT-IR Investigation Methane to Syngas over of Partial Oxidation of Rh/SiO2 Catalyst

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Journal of Natural Gas Chemistry 2007年第3期16卷 316-321页

作者： Tinghua Wu Dongmin Lin Ying Wu Xiaoping Zhou Qiangu Yan Weizheng Weng Huilin Wan Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces Institute of Physical Chemistry Zhejiang Normal University Jinhua 321004 Zhejiang China State Key Laboratory for Physical Chemistry of Solid Surfaces Xiamen University Xiamen 361005 Fujian China Center for Advanced Vehicular Systems Box 5405 Mississippi State University Starkville MS39762 USA

Partial oxidation of methane to syngas （POM） over Rh/SiO2 catalyst was investigated using in-situ FT-IR. When methane interacted with 1.0wt%Rh/SiO2 catalyst, it was dissociated to adsorbed hydrogen and CHx species. The adsorbed hydrogen atoms were transferred to SiO2 surface by ＂spill-over＂ and reacted with lattice oxygen to form surface -OH species. POM mechanism was investigated over Rh/SiO2 catalyst using in-situ FT-IR. It was found that CO2 was formed before CO could be detected when CH4 and O2 were introduced over the preoxidized Rh/SiO2 catalyst, whereas CO was detected before CO2 was formed over the prereduced Rh/SiO2 catalyst.

关键词： partial oxidation syngas Rh/SiO2 catalyst in-situ FT-IR

Oscillations during partial oxidation of methane to synthesis gas over Ru/Al_2O_3 catalyst

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Journal of Natural Gas Chemistry 2009年第3期18卷 300-305页

作者： Meiliu wang Weizheng Weng Haozhuan Zheng Xiaodong Yi Chuanjing Huang Huilin Wan State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols Ethers and Esters and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen UniversiO Xiamen 361005 Fujian China

Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al2O3 in the temperature range of 600 to 850℃. XRD, H2-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species, i.e. the ruthenium species weakly interacted with Al2O3 and that strongly interacted with the support, were identified by H2-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations, in turn, were the result of temperature variations caused by the varying levels of the strongly exothermic CH4 combustion and the highly endothermic CH4 reforming （with H2O and CO2） reactions （or the less exothermic direct partial oxidation of methane to CO and H2）, which were favored by the oxidized and the metallic sites, respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism.

关键词： Ru/Al2O3 methane partial oxidation synthesis gas oscillation

Ultrafiltration Membrane Performance in Treatment for Dyeing Effluent from Hairwork Industry on High Filtrate Recovery

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Ultrafiltration Membrane Performance in Treatment for Dyeing...

河南省化学会2018年学术年会

作者： Qihua Hu Tiemei Li Yuefei Song Wenbo Qin Yueke Sun Huilin Wan Jing Fan School of Environment Henan Key Laboratory for Environmental Pollution ControlKey Laboratory of Yellow River and Huai River Water Environmental and Pollution ControlMinistry of EducationHenan Normal University

High water consumption and large amounts of discharged pollutants are the two critical environmental problems in hairwork industry[1]. Dying effluent, as a primary contributor of the hairwork wastewater, contains a high concentration of color, COD and NH-N. In order to test and verify the feasibility of ultrafiltration(UF) treatment for dying effluent, sedimentation-microfiltration pretreatment and UF treatment experiment was performed. The influence of UF system recovery, which ranges from 50% to 90%, on membrane performance and removal rates of multiple pollutants were investigated to determine an ideal system recovery. The results showed that both UF flux and removal rate declined with the increase of system recovery. UF flux remains a relatively high level until 10.7% of the total decrease occurred when recovery reaches 68%. The removal rates of pollutants peaked at 52% of system recovery, and then significantly declined at 64% of system recovery. UF treatment showed a good removal for colority, UV254 and COD, but an inadequate rejection for electrical conductivity and ammonia nitrogen even at low system recovery. Removal of particle matters had a higher tendency for large particles(>15 um) than small particles(4-15 um), and this tendency became more and more evident with the increase of system recovery(seen in Fig.1). Based on the results, 64% was selected as the optimal system recovery to balance the operating efficiency and pollutant removal of UF treatment.

关键词： Membrane performance Dyeing effluent Water reuse Filtrate recovery

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O2和CO在Ni(111)表面的吸附活化

物理化学学报 2018年第12期34卷 1358-1365页

作者：段园陈明树万惠霖厦门大学化学化工学院固体表面物理化学国家重点实验室醇醚酯化工清洁生产国家工程实验室福建厦门361005

采用高分辨电子能量损失谱(HREELS)、俄歇电子能谱(AES)和低能电子衍射(LEED)研究镍单晶表面氧物种及CO与O_2的共吸附。实验结果表明,Ni(111)表面氧化后存在两种氧物种,位于54me V能量损失峰的表面化学吸附氧物种和位于69 meV能量损失... 详细信息

采用高分辨电子能量损失谱(HREELS)、俄歇电子能谱(AES)和低能电子衍射(LEED)研究镍单晶表面氧物种及CO与O_2的共吸附。实验结果表明,Ni(111)表面氧化后存在两种氧物种,位于54me V能量损失峰的表面化学吸附氧物种和位于69 meV能量损失峰的表面氧化镍。首先,随着暴露氧量的增加,表面化学吸附氧物种的能量损失峰蓝移至58 meV;其次,通过真空退火及与CO相互作用考察,发现表面化学吸附氧物种较不稳定。在室温条件下,表面预吸附形成的表面化学吸附氧物种与CO共吸附,导致端位吸附CO增多,表明氧优先吸附在穴位上,随着CO暴露量的增加化学吸附氧物种与CO反应脱去;而表面氧化镍需在较高温度和较高CO分压下才能被CO还原。预吸附CO可被氧逐渐移去。

关键词： Ni(111) 高分辨电子能量损失谱表面O2和CO活化表面氧物种 CO吸附 CO和O2共吸附