Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over Al2O3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.     

Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over AlzO3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.     

Kinetic study on hydrolysis and oxidation of formamidine disulfide in acidic solutions

Hydrolysis and oxidation of formamidine disulfide in acidic medium were investigated using high-performance liquid chromatography(HPLC) and mass spectrometry(MS) at 25 °C.By controlling the slow reaction rate and choosing appropriate mobile phase,HPLC provides the unique advantages over other methods(UV-Vis,chemical separation) in species tracking and kinetic study.In addition to thiourea and formamidine sulfinic acid,two unreported products were also detected in the hydrolysis reaction.Mass spectrometry measurement indicates these two products to be formamidine sulfenic acid and thiocyanogen with mass weights of 92.28 and 116.36,respectively.In the oxidation of formamidine disulfide by hydrogen peroxide,besides thiourea,formamidine sulfenic acid,formamidine sulfinic acid,thiocyanogen and urea,formamidine sulfonic acid and sulfate could be detected.The oxidation reaction was found to be first order in both formamidine disulfide and hydrogen peroxide.The rate constants of hydrolysis and oxidation reactions were determined in the pH range of 1.5-3.0.It was found both rate constants are increased with the increasing of pH.Experimental curves of different species can be effectively simulated via a mechanism scheme for formamidine disulfide oxidation,including hydrolysis equilibrium of formamidine disulfide and irreversible hydrolysis of formamidine sulfenic acid.     

Fe/MCSAC catalysts surface modified with nitrogen DBD non‐thermal plasma for carbonyl sulfide catalytic hydrolysis activity enhancement

The removal of carbonyl sulfide (COS or S=C=O) from gas streams over Fe/microwave coconut‐shell activated carbon (MCSAC) catalysts modified by dielectric barrier discharge non‐thermal plasma (NTP) were investigated. The properties of Fe/MCSAC catalysts modified by NTP in different conditions, included kinds of reactors, treatment times and input voltages. The surface properties were evaluated by means of energy‐dispersive X‐ray spectrometry, Brunauer Emmett Teller, X‐ray photoelectron spectroscopy methods and theoretical calculation, which could help us understand the effects of the plasma treatment. The experiments results showed that the COS hydrolysis activities of Fe/MCSAC catalysts were largely enhanced after NTP modification. And the optimal reactor type, treatment time and input voltage were plate‐plate type, 10 min and 35 V, respectively. The catalytic activity enhanced effectually due to the improvement of active component's dispersion after NTP modification. In addition, the extended oxygen functional groups on NTP‐modified catalyst's surface could contribute to a higher activity for COS catalytic hydrolysis at low temperature. The investigation results indicate that non‐thermal plasma treatment is an effective way to manipulate catalyst surface properties for COS catalytic hydrolysis reaction. Copyright © 2017 John Wiley & Sons, Ltd.     

Theoretical study on the mechanism of the gas-phase reaction of diborane(3) anion with carbon disulfide

The complex potential energy surface of the gas-phase reaction of HB(H)BH- with CS2 to give three low-lying products [B2H3S]- + CS, [BH2CS]- + HBS, and [BH3CS] + BS-, involving nine [B2H3CS2]- isomers and 12 transition states, has been investigated at the CCSD(T)/6-311++G(d,p)/B3LYP/6-311++G(d,p) level. Our calculations are in harmony with the recent experimental and theoretical results, and reveal some new bonding and kinetic features of this reaction system. Our theoretical results may help the further identification of the products [BH2CS]- + HBS and [BH3CS] + BS- and may provide useful information on the chemical behaviors of other electron-deficient boron hydride anions.     

Textural characteristics, surface chemistry and oxidation of activated carbon

Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation. Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its "Textural Characteristics" and "Surface Chemistry". These two terms, coupled with each other, are responsible for behavior of activated carbon in adsorption processes and in catalytic applications. Although as-prepared activated carbons are usually non-selective and their surfaces suffer from lack of enough reactive groups, their different aspects may be improved and developed by diverse types of modifications. Oxidation is one of the most conventional modifications used for activated carbons. It may be used as a final modification or as a pre-modification followed by further treatment. In this paper, methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.     

活性炭的表面处理对二苯并噻吩催化氧化脱除的影响

将一种木质活性炭经过三种表面处理,即高锰酸钾稀硫酸溶液液相氧化、浓硝酸液相氧化和350℃低温气相氧化处理。实验所选活性炭及相应的表面改性炭使用氮气吸附和Boehm滴定分别进行了结构性质和表面化学表征。研究了所选活性炭和相应的表面改性炭催化过氧化氢氧化脱除二苯并噻吩（DBT）。实验结果表明,活性炭表面化学对二苯并噻吩的氧化脱除影响很大;炭表面化学对DBT吸附脱除的影响不同于对DBT氧化脱除的影响,表面酸性越强越有利于DBT的吸附;表面羰基能加速过氧化氢产生自由基,表面羰基量的增加明显有利于DBT的氧化脱除。活性炭经过热处理后,在二苯并噻吩的氧化脱除中催化活性明显增加,正辛烷溶液中硫的体积质量从0.556g·L-1降到0.009g·L-1。     

第一性原理研究C在Fe(111)表面和次表面的积炭机理

使用密度泛函方法对C原子在Fe(111)表面吸附团聚和次表层的吸附扩散进行了研究。在炭覆盖度θ_C <1 ML时,C主要以孤立的原子态存在并导致表面重构;1 ML≤θ_C ≤2 ML,"mC₂+nC"为主要的吸附形式;θ_C≥2 ML时,复杂的吸附形态比如碳链和岛状碳团簇开始生成。这些复杂岛状碳团簇是Fe(111)表面石墨沉积或碳纳米管生长的成核中心。在次表层,C原子在八面体位稳定存在。C在表面的迁移能垒为0.45 eV,由表面迁移到次表面的的能垒为0.73 eV。虽然C₂团簇的生成是热力学有利的,但是C向次表层的迁移动力学上占优。     

First-principles study of the mechanism of carbon deposition on Fe(111) surface and subsurface

使用密度泛函方法对C原子在Fe(111)表面吸附团聚和次表层的吸附扩散进行了研究.在炭覆盖度θc＜1ML时,C主要以孤立的原子态存在并导致表面重构;1ML≤θc≤2ML,“mC2+nC”为主要的吸附形式;θc≥2ML时,复杂的吸附形态比如碳链和岛状碳团簇开始生成.这些复杂岛状碳团簇是Fe(111)表面石墨沉积或碳纳米管生长的成核中心.在次表层,C原子在八面体位稳定存在.C在表面的迁移能垒为0.45eV,由表面迁移到次表面的的能垒为0.73eV.虽然C2团簇的生成是热力学有利的,但是C向次表层的迁移动力学上占优.     

Synthesis of dimeric estradiol enzyme model containing imidazolyl and study on its catalytic efficiency in hydrolysis of carboxylates and phosphates

Dimeric estradiol enzyme model (2) was synthesized by etherification of 2,4-bis(N-imidazolylmethyl)-17β-estradiol (1) with 1,3-dibromopropane in the presence of anhydrous K2CO3. Hydrolysis of carboxylates and phosphates catalyzed by the model showed Michaelis-Menten kinetic behavior. Hydrophobic interaction between the model and ester accelerates the hydrolysis markedly, rate enhancement of up to 65 and 285 fold, relative to imidazole, is observed.     

Influence of surface properties on the interfacial adhesion in carbon fiber/epoxy composites

A polyacrylonitrile‐based carbon fiber was electrochemically oxidized in an aqueous ammonium bicarbonate solution with current density of up to 2.76 A/m² at room temperature. X‐ray photoelectron spectroscopy revealed that the oxygen content increased with increasing current density before approaching saturation. The increase can be divided into two regions, the rapid increase region (0–1.78 A/m²) and a plateau region (1.78–2.76 A/m²). The surface chemistry analysis showed that the interlaminar shear strength (ILSS) value of the carbon fiber/epoxy composite could be improved by 24.7%. The carbon structure was examined using Raman spectroscopy in terms of order/disorder in the graphite structure and the results indicated that the relative percentage of graphite carbon in the form of sp² hybridization increased above a current density of 1.39 A/m². The increasing non‐polar graphite carbon on the carbon fiber surface decreased the surface energy. As a result, both the surface free energy () and its polar component () decreased when current density increased above 1.78 A/m². The ILSS value had no direct relationship with the nature and surface density of the oxygen‐containing functional groups nor with the carbon structure. It is the surface free energy (), especially the polar component (), which played a critical role in affecting the interfacial adhesion of carbon fiber/epoxy composites. The ILSS value changed with increasing current density and could be divided into three distinct regions, as chemical interaction region (I), anchor force region (II) and matrix damage region (III). Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of the thermal decomposition of surface oxygen species on the chemical and catalytic properties of activated carbon supported Pt catalysts

Several carbon supported Pt catalysts were prepared by varying surface properties of support and tested for methylene chloride oxidation. They were investigated by BET, TPD, pH analysis and XPS. The Pt species would stabilize when the surface carbon was pregraphitized due to the π sites of basal plane. This revised version was published online in June 2006 with corrections to the Cover Date.     

Promotional effect of acidic oxide on catalytic activity and N2 selectivity over CeO2 for selective catalytic reduction of NOx by NH3

The CeO₂, CeO₂‐ZrO₂ and CeO₂‐WO₃ catalysts were prepared by hydrothermal method and used to the selective catalytic reduction of NO_x by NH₃. The addition of ZrO₂ or WO₃ into CeO₂ was favorable for pore structure, and then improved the number of active sites. Besides, the introduction of ZrO₂ into CeO₂ could improve the Lewis acid sites while WO₃ could contribute to the generation of Brønsted and Lewis acid sites, which could improve the catalytic performance and N₂ selectivity. The CeO₂‐WO₃ catalyst exhibited optimal catalytic activity with above 90% NO_x conversion performance at 220–425 °C and approximately 100% N₂ selectivity at 150–425 °C.     

活性炭（焦）低温吸附催化脱除H2S的基础研究

以活性炭、活性焦作为脱硫剂,并应用BET、XPS等测试手段对其进行分析表征。结果表明,活性炭（焦）的脱硫能力与其表面酸碱性有着密切的关系,增加表面上起碱性作用的π-π^﹡键,羰基官能团（C-O和醚基官能团（C-O）的浓度,可增加其表面催化作用,特别是C-O官能团;反应温度对活性炭（焦）的脱硫性能有很大的影响,脱硫剂在150℃～180℃活性高,硫容大,副反应少;水蒸气对活性炭（焦）脱除H₂S有促进作用。     

Study on the friction and wear behavior of surface‐modified carbon nanotube filled carbon fabric composites

The functionalization of multi‐walled carbon nanotubes (MWNTs) was achieved by grafting furfuryl amine (FA) onto the surfaces of MWNTs. Furthermore, the functional MWNTs were incorporated into carbon fabric composites and the tribological properties of the resulting composites were investigated systematically on a model ring‐on‐block test rig. Friction and wear tests revealed that the modified MWNTs filled carbon fabric composite has the highest wear resistance under all different sliding conditions. Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) revealed that MWNTs were successfully functionalized and the modification led to an improvement in the dispersion of MWNTs, which played an important role on the enhanced tribological properties of carbon fabric composites. It can also be found that the friction and wear behavior of MWNTs filled carbon fabric composites are closely related with the sliding conditions such as sliding speed, load, and lubrication conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

冠醚Schiff碱金属配合物的合成及其模拟膦酸酯水解酶的动力学研究

合成和表征了两种新的冠醚Sehiff碱锰(Ⅲ)和钴(Ⅱ)配合物,并对其催化膦酸二酯(BNPP)水解的动力学进行了研究。结果表明,这两种冠醚Sehiff碱锰(Ⅲ)和钴(Ⅱ)配合具有较高的催化活性。     

Effect of the graphitic degree of carbon supports on the catalytic performance of ammonia synthesis over Ba-Ru-K/HSGC catalyst

A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.     

Ce掺杂对碳纳米管负载Mn催化剂结构及SCR反应性能的影响

采用等体积浸渍法制备多壁碳纳米管(MWCNTs)负载Ce-Mn的催化剂,考察了Ce掺杂对Mn/MWCNTs催化剂上NH₃选择性催化还原(SCR)NO_x反应活性的影响.并运用透射电镜扫描、N₂吸附-脱附、程序升温还原、X射线光电子能谱、X射线衍射等手段,重点考察了Ce掺杂对Mn/MWCNTs催化剂结构性质的影响.结果表明,Ce掺杂能显著提高催化剂的SCR活性,其活性增量随着Ce含量的增加先增大后减小;当Ce/Mn为0.6时,催化剂活性最佳.表征结果显示,Mn/MWCNTs中添加Ce后,金属氧化物在MWCNTs上的分散程度提高;催化剂的比表面积和孔体积增大,平均孔径减小;氧化能力提高;表面氧含量增加,Mn化合价升高;结晶度降低,Mn主要以无定形或微晶形式存在,Ce主要以CeO₂物相存在.     

Influence of hydrothermal exposure on surface characteristics and corrosion behaviors of anodized titanium

Titanium surface was modified by anodization in phosphoric acid solution at the voltages of 100 and 250 V, respectively. Surface characteristics and corrosion behaviors of anodized titanium were investigated before and after hydrothermal exposure in 3.5 wt.% NaCl solution at 160 °C for 24 h. It was found that anodization at 100 and 250 V resulted in the formation of a dense and a porous TiO₂ layer, respectively. The existence of anatase in the oxide layers of the 250‐V samples was confirmed by X‐ray diffraction analysis but not in the oxide layers of the 100‐V samples. After the hydrothermal exposure, the surface morphology of the 100‐V sample changed significantly, and discrete nanorods were formed on the surface. In contrast, the 250‐V sample basically preserved their original surface structures after the exposure except that numerous closely packed nanoparticles emerged on the surface. X‐ray diffraction analysis indicated that the exposure transformed the amorphous oxides into crystalline anatase. The corrosion behavior investigation of anodized titanium showed that the hydrothermal exposure had slight influence on the corrosion resistance of the 100‐V samples but decreased the corrosion resistance of the 250‐V samples significantly. Copyright © 2014 John Wiley & Sons, Ltd.     

Adsorption of water vapor on a non-porous carbon surface and evaluation of the mesopore surfaces of active carbons

Adsorption of water vapor on non-porous carbon adsorbents (blacks) with different specific surfaces and a sufficiently high concentration of primary centers was studied. The maximum value of the adsorption is proportional to the surface and corresponds to the formation of (1.7±0.3) dense monomolecular layers. A method was proposed for determining the surface of non-porous carbon adsorbents and for evaluating the mesopore surfaces of active carbons.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2048–2051, December, 1993.This work was supported by the Russian Foundation for Basic Research (Grant 93-035635).