CH3S自由基H迁移异构化及脱H2反应的直接动力学研究

采用密度泛函方法(MPW1PW91)在6-311G(d,p)基组水平上研究了CH₃S自由基H迁移反应CH₃S→CH₂SH (R1), 脱H₂反应CH₃S→HCS＋H₂ (R2)以及脱H₂产物HCS异构化反应HCS→CSH (R3)的微观动力学机理. 在QCISD(t)/6- 311＋＋G(d,p)//MPW1PW91/6-311G(d,p)＋ZPE水平上进行了单点能校正. 利用经典过渡态理论(TST)与变分过渡态理论(CVT)分别计算了各反应在200～2000 K温度区间内的速率常数k^TST和k^CVT, 同时获得了经小曲率隧道效应模型(SCT)校正后的速率常数k^CVT/SCT. 结果表明, 反应 R1, R2 和R3的势垒△E^≠分别为160.69, 266.61和241.63 kJ/mol, R1为反应的主通道. 低温下CH₃S比CH₂SH稳定, 高温时CH₂SH比CH₃S更稳定. 另外, 速率常数计算结果显示, 量子力学隧道效应在低温段对速率常数的计算有显著影响, 而变分效应在计算温度段内对速率常数的影响可以忽略.     

Laser induced chemiluminescence of BCl3/H2S mixtures

Visible chemiluminescence has been observed from mixtures of BCl₃ and H₂S when subjected to intense 10.6 μm radiation from a CO₂ laser. The spectrum of the emission is found to contain a molecular band structure superimposed on an underlying continuum. The visible fluorescence displays a strong dependence on the incident CO₂ laser power and a temporal component that is faster than gas collision times. The implications of this with regard to laser isotope separation are discussed.     

LaCoO3对H2S选择氧化性能的影响

使用溶胶-凝胶法制备了LaCoO₃催化剂,采用XRD、BET和XPS等方式对催化剂进行了表征,考察了该催化剂制备过程中煅烧温度、表面活性剂PEG-6000和PEG-20000含量对其H₂S选择氧化制硫磺反应催化活性的影响。结果表明,表面活性剂PEG-6000及PEG-20000的添加能明显提高LaCoO₃的催化活性。0.02 mol La（NO₃）₃+0.02mol Co（NO₃）₂溶液中添加0.30 g PEG-20000、煅烧温度为650℃时所制备的LaCoO₃催化活性最好;在最佳反应温度260℃下,H₂S的转化率达到96.10%,硫选择性为93.77%。     

Reaction of dodecanol-1 with H2S on acid catalysts

The reaction of dodecanol-1 with H₂S has been studied at 275°C and 0.1 MPa on acid catalysts. Catalysts having only strong proton sites accelerate alcohol dehydration, whereas catalysts with Lewis acid sites support dodecanethiol-1 formation as well. The catalytic activity per one Lewis acid site rises with the increase of the site strength.     

Comparison of the sulfurization of CoMoK/Al2O3 catalyst with H2S and CS2

Only H₂S consumption and H₂O formation was found in the sulfurization of CoMoK/Al₂O₃ water gas shift catalyst with H₂S/H₂, but CO₂ was formed first, then CH₄, H₂O and H₂S appeared in the later part of TPS with CS₂/H₂. Carbon deposition on the catalyst during the sulfurization with CS₂/H₂ caused a lower activity than the catalyst sulfurized with H₂S but could be removed in the run of WGS reaction.

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, CoMoK/Al₂O₃, H₂S/H₂ H₂S H₂O, CS₂/H₂ CO₂ CH₄, H₂O H₂S. CS₂/H₂ H₂S, , .

     

Infrared spectroscopic studies of H2S adsorption on γ-Al2O3

IR spectra of H₂S adsorbed in various quantities on -Al₂O₃ have been studied. The method of spectral probes has been used to determine the extent of H₂S blocking of Lewis acid and basic centers.

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- , -Al₂O₃. .

     

利用H2与金属氧化物的选择性反应从CO中除H2

研究了一些氧化物的H2－TPR及CO－TPR行为,结果发现,Co3O4／Al2O3,NiO／SiO2,NiO和Pd／NiO的H2－TPR温度要低于它们的CO－TPR温度,特别是Pd／NiO样品,它的H2－TPR温度为598K,而其CO－TPR温度高达949K,差别为351K,因此有可能利用Pd／NiO在一定温度下选择性地与CO中的H2反应而将其除去. 实验结果表明,Pd／NiO可在603K及4000h-1的条件下从H2（0.34％）,CO（50％）和N2（余）的混合气中选择性地除去90％以上的H2,吸氢容量为每克样品55mL标准态H2.     

H2S/H2硫化温度对MoP/SiO2催化剂硫醚化性能的影响

以负载磷酸钼为前驱体,采用程序升温还原法制备了MoP/SiO₂催化剂,以体积分数3%H₂S/H₂对其进行了硫化处理,利用XRD、CO化学吸附、NH₃-TPD、HRTEM-EDX、ICP-AES以及XPS等手段对催化剂进行了表征,研究了硫化温度对MoP/SiO₂催化剂结构和异戊二烯与正丁硫醇硫醚化性能的影响。结果表明,即使在400℃硫化处理也未改变MoP/SiO₂催化剂中MoP体相结构;随着硫化温度提高,催化剂表面酸量增加、金属位数量减少,降低了催化剂C-S键氢解及异戊二烯深度加氢活性,但同时也提高了催化剂烯烃聚合活性。经120℃硫化处理的MoP/SiO₂兼具较佳硫醚化及异戊二烯选择加氢性能。     

Molecular predissociation dynamics revealed through multiphoton ionisation spectroscopy. III. New 1A2 and 1B1 rydberg states in H2S D2S

Two new Rydberg series in H₂S and D₂S habe been characterized as three-photon resonances in four-photon ionisation spectrometry. Members of the two series exhibit sufficient rotational structure to permit characterisation of their electronic symmetries as, respectively. A₂ and B₁. The first Rydberg series is identified with the (one-photon forbidden) excitations npb₂ ← 2b₁ (¹A₂ ← $\text{X}$¹A₁) on the basis of the observed quantum defects. Geometry considerations indicate that second series, of ¹B₁ states, also arises as a result of electronic promotion from the highest occupied 2b₁ orbital. The acceptor (a₁) Rydberg orbitals possess substanial s character, but the polarisation dependence of the various ¹B₁-$\text{X}$¹A₁ three-photon transition probabilities their hybrid I character, d (and quite possibly p) functions contribute also. The results provide further clear demonstration of the way in which multiphoton excitations, and MPI techniques in particular, can complement conventional one-photon absorption techniques. Members of both series are predissociated. Vibronic predissociation rates are found generally to decline with increasing n and to be slower in D₂S than in H₂S. The lowest (n = 4) member of the ¹A₂ series in both isotopic species appears immune from rovibronic predissociation but higher members show evidence of a ($\text{J}$_a²)-dependent rotationally-induced predissociation, the severity of which increases dramatically with n. This observation is explained in terms of electronic-rotational Coriolis coupling to a dissociated ¹B₂ state is presumed to be responsible for the observed ($\text{J}$_b²)-dependent heterogeneous predissociation of the ¹B₁ (n = 6) member in H₂S. However, the dominant rotationally-induced predissociation mechanism that affects the counterpart in D₂S scales with ($\text{J}$_a²). Wherever possible comparisons are drawn with the known spectroscopy and photophysics of the isovalent molecules H₂O and D₂O.     

Deactivation of vibrationally excited N2 by H2O

The VV exchange rate for the N₂H₂O system is determined using a hard-core repulsive potential. It is found that the rapid deactivation rate arises from near-resonant VR exchanges involving non-dipole changes in the rotational states. Furthermore, a classical-path approximation is used and the resulting rate found to be critically dependent on the path chosen.     

Assembly of Pt nanoparticles on electrospun In2O3 nanofibers for H2S detection

In this paper, we presented a simple and effective solution route to deposit Pt nanoparticles on electrospun In₂O₃ nanofibers for H₂S gas detection. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed that large quantities of In₂O₃ nanofibers with diameters about from 60 to 100 nm were obtained and the surface of them was decorated with Pt nanoparticles (5–10 nm in size). The In₂O₃ nanofibers decorated by Pt nanoparticles exhibited excellent gas sensing properties to H₂S, such as high sensitivity, good selectivity and fast response at relatively low temperature.     

Dipole moment derivatives of H2O and H2S

The dipole and quadrupole derivatives of H₂O and H₂S are calculated analytically, using the coupled Hartree—Fock method first proposed by Gerratt and Mills. The greater efficiency, of this method allows SCF wave functions very, close to the Hartree—Fock limit to be used. Agreement, with experimental data is good.     

Catalytic reaction of tetrahydrofuran with H2S

The reaction of tetrahydrofuran with H₂S catalyzed by acid-base catalysts has been studied. Catalysts containing an acid-base pair, i.e. a Lewis acid center and a base center, are the most active and selective towards thiolane. Proton donor catalysts and those containing only basic centers are of low activity and selectivity.

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H₂S - . , - : - , . , , .

     

XPS- und AES-Untersuchungen an Eisen-Kupfer-Legierungen nach kathodischer Polarisation in H2SO4/H2S

Ohne Zusammenfassung

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XPS- and AES-studies of iron-copper alloys after cathodic polarization in H₂SO₄/H₂S

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Eine ausführliche Veröffentlichung unter stärkerer Berücksichtigung der elektrochemischen Untersuchungen findet sich in Corrosion Science (1984) 24:591–611: C. Kato, H. J. Grabke, B. Egert und G. Panzner, Electrochemical and Surface Analytical Studies on Hydrogen Permeation with Fe-Cu Alloys in Sulfuric acid with and without H₂S.     

程序升温表面反应技术研究氧化铈上H2S的吸附和转化

采用程序升温表面反应技术研究了H2S在CeO2,TiO2和Al2O3三种载体上的吸附和反应行为.结果表明,CeO2具有最强的脱硫能力.系统研究了预处理气氛对H2S在CeO2上吸附和反应行为.发现CeO2的脱硫能力在惰性气氛、还原性气氛、氧化性气氛中依次增强.H2S首先吸附在经预处理的CeO2表面,进一步在Ar氛围下升温脱附时,一部分H2S在673 K以下脱附,部分则与CeO2表面氧反应,在473 K下产生硫和水,而在473～673 K温度范围内,生成SO2.在673 K以上,所生成的SO2进一步与晶格氧反应,转化成硫酸盐.后者在873 K再次分解为SO2.因此,CeO2表面脱硫过程应控制在67     

High-temperature FeS-FeS2 solid-state transitions: Reactions of solid mackinawite with gaseous H2S

Phase transitions and reactions of non-oxidized and surface-oxidized mackinawite (FeS) in helium and H₂S gas were investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). DFT was used to obtain optimized structures of the iron-sulfur phases mackinawite, hexagonal pyrrhotite, greigite, marcasite and pyrite and to determine the thermochemical properties of reactions of mackinawite with H₂S to these phases. The phase transitions of mackinawite to hexagonal pyrrhotite are endothermic, while reactions to greigite, marcasite and pyrite are exothermic. The experiments show that non-oxidized mackinawite converts into hexagonal pyrrhotite (Fe₉S₁₀ first and then Fe₇S₈) in He and also in H₂S but at a lower temperature. No further reactions can be observed under these conditions. In the case of surface-oxidized mackinawite, the extent of surface oxidation determines the course and the final product of the reaction with H₂S. If the extent of surface oxidation is low, only Fe²⁺ is oxidized to Fe³⁺. Under these conditions mackinawite converts into the mixed-valence thiospinel compound greigite. In case of pronounced surface oxidation all surface Fe centers are oxidized to the Fe³⁺ state and S²⁻ is oxidized to SO₄²⁻. Oxidation of sulfur is a prerequisite for the formation of pyrite.     

H2O2-鲁米诺-荧光素钠-K2CO3高灵敏化学发光法测定二氧化碳

在碱性介质中, CO₃^2－对H₂O₂氧化鲁米诺化学发光反应具有重要作用, 荧光素钠对该反应具有很强的增敏作用. 据此, 建立了化学发光法测定二氧化碳的新方法. 方法的线性范围为1.0×10^－10～5.0×10^－6 mol•L^－1 CO₃^2－, 检出限为 1.2×10^－11 mol•L^－1 CO₃^2－ (相当于5.3×10^－10 g•L^－1 CO₂). 该方法用于室内外空气中二氧化碳含量的测定, 相对标准偏差1.8%～2.1% (n＝11), 加标实验回收率97.6%～101.4%. 论文还探讨了反应的发光机理, 发光反应很可能是由溶液中的CO₃^2－与H₂O₂作用而产生的活性自由基引发, 荧光素钠对发光的增敏作用为化学能量转移过程.     

CH3S与HO2气相反应机理的理论研究

采用密度泛函理论的B3LYP方法, 在6-311＋＋G(d,p)基组水平上研究了CH3S自由基与HO2自由基的微观反应机理, 全参数优化了反应势能面上各驻点的几何构型, 振动分析和内禀反应坐标(IRC)分析结果证实了中间体和过渡态的真实性, 计算所得的键鞍点电荷密度的变化情况也确认了反应过程. 找到了五条可能的反应通道, 对结果的分析表明: 单线态反应通道(5) CH3S＋HO2→CH3SOOH (1P), 是所有通道中的主要反应通道. 该通道不需要克服过渡态能垒, 属于放热反应, 在动力学和热力学上都是最为有利的. 对于三线态反应通道来说, 通道(1)CH3S＋HO2→COM11→TS1→COM12→CH3SH＋O2 (3P)为主要反应通道, 控制步骤的活化能为53.5 kJ/mol, 能垒最低, 属于放热反应, 在动力学和热力学上都是有利的.