离子色谱-化学发光法测定环境水样中痕量间苯二酚和间苯三酚

建立了离子色谱分离化学发光法同时检测环境水样中痕量间苯二酚和间苯三酚的方法。利用IonPacAS19阴离子交换分析柱进行分离,以50 mmol/LNaOH作为流动相洗脱待测物质后,再用鲁米诺K₂Fe（CN）₆化学发光体系在碱性介质中对其进行测定。最佳发光条件为:鲁米诺浓度为6.0×10^-4mol/L,K₄Fe（CN）-6浓度为0.1 mol/L,K₃Fe（CN）₆浓度为5.5×10^-5mol/L。本方法分离时不需使用甲醇、乙腈等有机改进剂,环境友好,同时提高了化学发光的强度。采用本方法测定的间苯二酚和间苯三酚线性范围为0.05～1.0 mg/L,检出限（3σ）分别为4.0和4.3μg/L。对0.1 mg/L的间苯二酚和间苯三酚标准溶液进行11次测定,相对标准偏差（RSD）分别为0.9%和1.1%。将本方法应用于实际水样中痕量间苯二酚和间苯三酚的检测,结果满意。     

基于密度泛函理论的CO2氧化含氮焦炭的机理研究

本研究基于密度泛函理论,选取简化的含吡咯氮（N-5）或吡啶氮（N-6）焦炭模型,在分子水平上对CO₂氧化含氮焦炭的异相反应机理进行研究。结构优化采用B3LYP-D3/6-31G（d）方法,单点能计算采用B3LYP-D3/def2-TZVP方法。计算结果表明,CO₂氧化含氮焦炭过程分为CO₂吸附、CO脱附和NO脱附三个阶段。CO₂异相氧化含吡咯氮焦炭的反应中,CO₂分子倾向于以C-O-down模式（N-O结合、C-C结合）吸附形成含氮和氧的五元杂环结构。然后五元环中原CO₂分子的C-O键断裂形成表面羰基和表面氮氧结构,分别解吸附出CO和NO。该反应吸热401.2 kJ/mol,决速步能垒为197.6 kJ/mol。CO₂异相氧化含吡啶氮焦炭的反应中,CO₂分子以C-O-down和C-C结合、C-O结合模式吸附后倾向于先形成含氮和氧的六元杂环,再发生CO和NO分子的脱附。该反应吸收598.6 kJ/mol的热量,决速...     

氮化铌电催化还原CO2

通过电化学的方法将CO₂转化为CO是解决资源和环境问题的经济友好的策略。在本次工作中,利用湿化学方法制备了铌/碳的前驱体,在NH₃和Ar氛围下煅烧后分别转化为Nb₄N₅/C和Nb₂O₅/C。当氮化温度达到700℃时,制备的Nb₄N₅/C表现出优异的催化活性,在CO₂饱和的0.5 mol·L^-1的NaCl溶液中,电解电位为-0.83V（RHE）时,CO的法拉第效率最高,达到57%。实验结果表明,Nb₄N₅/C的催化活性与Nb₄N₅中的N掺杂有关。     

多酸基复合光催化剂的合成及其太阳光驱动CO2制甲酸研究在实验教学中的设计与探究

温和条件下将二氧化碳(CO₂)高效转化为高值化学品,不仅可以实现碳资源的循环利用,也对减缓温室效应具有重要意义。本实验基于多酸(POMs)复合催化剂制备及其应用于光催化CO₂加氢制甲酸的创新性研究成果,设计了适合本科实验教学的综合创新实验。实验采用浸渍法将Anderson型多酸[H₆(CrO₆)Mo₆O₁₈]^3-分散到TiO₂表面形成多酸复合光催化剂CrMo₆/TiO₂,通过X射线粉末衍射和红外光谱解析了催化剂的结构。利用气相色谱和液相色谱对光催化产物进行分析检测,结果显示,光照条件下CrMo₆/TiO₂复合光催化剂可催化CO₂高选择性转化为液体产物甲酸。紫外-可见光谱分析证实,多酸的修饰减小了TiO₂能带间隙,增加了光谱的吸收范围,提升了光催化性能。本实验内容涵盖了无机材料合成、仪...     

BMIMBF4中2-氨基-3-氯-1,4-萘醌电化学捕获CO2的机理

利用循环伏安法（CV）和现场红外光谱电化学技术研究了2-氨基-3-氯-1,4-萘醌（ACNQ）在1-丁基-3-甲基咪唑四氟硼酸盐（BMIMBF₄）中电化学捕获CO₂的机理.研究结果表明,当体系中不存在CO₂时,ACNQ在BMIMBF₄中经历可逆的两步一电子过程;当体系中引入CO₂时,电化学还原过程中形成的二价阴离子（ACNQ^2-）作为亲核试剂,可攻击CO₂的亲电子碳中心,形成稳定的CO₂加合物.对电化学捕获CO₂的化学计量进行了评估,结果表明,1摩尔的ACNQ^2-可捕获1摩尔的CO₂.结合B3LYP方法在6-311++G^**水平上计算分析了反应中CO₂加合物可能的结构.     

CO2在α-U(001)表面的吸附和解离

采用广义梯度密度泛函理论研究了0.25ML覆盖度下CO₂在α-U（001）表面上的吸附和解离,得到了CO₂的稳定吸附构型和吸附能,确定了CO₂的解离过渡态和解离能垒,探讨了CO₂与表面U原子的相互作用本质.结果表明CO₂趋向以C（O）-U多键结合方式在α-U（001）面发生强化学吸附,吸附能为1.24-1.67 eV;C-O键的活化程度依赖于表面电子向CO₂发生转移的程度.CO₂与表面U原子的相互作用主要来自于U原子电子向CO₂最低空轨道（LUMO）2π_u转移,以及CO₂π_u/1π_g/3σ_u-U 6d轨道间杂化而生成新的化学键.以形成3个C-U键和6个O-U键模式在穴位1和穴位2上发生吸附的CO₂（H1-C₃O₆和H2-C₃O₆）的解离吸附能分别为3.15和3.13 eV,解离能垒分别为0.26和0.36 eV,预示着吸附CO₂分于易于解离形成CO分子和O原子.     

纳米晶枝CuAu 合金催化剂对二氧化碳电催化还原性能的研究

利用可再生清洁能源将CO₂转化为CO和其他小分子是合成含碳燃料的可观方法之一。间歇性可再生能源存储的重要策略之一是将二氧化碳进行电化学还原。选择具有高活性和稳定性的电催化剂对于电化学还原CO₂至关重要。在这项研究中,我们使用简单的电沉积方法合成了具有纳米晶枝状结构的CuAu合金电极。各项表征显示原子比约为1:1的CuAu纳米枝晶对CO₂的电化学还原具有出色的催化活性。合成的主要产物是H₂和CO,这是合成气体是合成天然气,氨和甲醇合成的中间体。电化学阻抗谱（EIS）测量表明,相对于Cu和Au电沉积催化剂,CuAu纳米晶枝状催化剂具有相对低的电荷转移阻力。CuAu纳米枝晶催化剂是一种具有潜在的转化CO₂为合成气体的高活性电催化剂。     

固相萃取-离子色谱法测定地下水中痕量高氯酸根离子

建立了测定地下水中痕量高氯酸根（ClO~4）的固相萃取-离子色谱(SPE-IC)分析方法。0.7 L水样经预处理降低主要干扰离子Cl~、CO2~3和SO2~4的干扰后,使用Cleanert PWAX弱阴离子交换固相萃取小柱对地下水中痕量(μg/L级)的ClO~4进行富集,用6 mL 1%NaOH溶液洗脱,富集液经0.45 μm水膜过滤后,用IonPac AS20阴离子分离柱、50 μL进样环、40 mmol/L KOH溶液淋洗、抑制电导检测分离分析。结果表明,地下水样品中ClO~4的方法检出限和测定下限分别为0.15 μg/L和0.60 μg/L,进样质量浓度在1～15 μg/L范围内有很好的线性关系,线性相关系数为0.9992,回收率为99.7%～100.5%;该方法经济有效,可用于地下水中痕量ClO~4的检测。利用该方法测定了哈尔滨周边部分地区地下水中ClO~4浓度,检测结果与离子色谱-质谱联用法的检测结果的相对误差为1.85%～9.24%。     

高效液相色谱法同时测定水体中氧氟沙星及其手性异构体

建立了一种简单快捷的手性配位交换高效液相色谱测定地表水中氧氟沙星及其手性异构体的方法,并研究了常见金属阳离子（Ca²⁺、Mg²⁺、Fe³⁺、Zn²⁺）和腐殖酸（HA）对二者分离的影响。采用C₁₈色谱柱（25 cm×0.46 cm,5 μm）,流动相为pH值4.5的20%（v/v）甲醇水溶液（含4 mmol/L异亮氨酸（配体）和3 mmol/L CuSO₄）,流速为1.0 mL/min,柱温为40℃,检测波长为293 nm。氧氟沙星及其手性异构体左氧氟沙星可在18 min内分离,分离度（R）为2.70。结果表明,不同金属阳离子和腐殖酸对手性分离未见明显影响,但会降低氧氟沙星及其手性异构体的峰面积,其中Fe³⁺和高浓度腐殖酸的影响最大。该法能够快速高效测定地表水中氧氟沙星及其手性异构体,但在测试中需考虑Fe³⁺和高浓度腐殖酸的影响。     

Pd/C催化剂用于CO2电化学还原生成CO:Pd载量的影响

CO₂电化学还原反应可以将CO₂转化为燃料并同时实现再生能源的有效存储. 目前纳米结构的多相催化剂已经广泛应用于此反应,其中碳负载钯纳米粒子（Pd/C）表现出优异的CO₂电化学还原性能. 本工作研究了钯载量对于Pd/C催化剂结构以及其催化CO₂还原生成CO反应活性和选择性的影响. 不同载量的Pd/C催化剂通过液相还原方法制备,钯纳米粒子均匀地分散在碳载体上,载量并没有明显改变对纳米粒子的粒径. 在优选的电解质（0.1 mol·L^-1 KHCO₃）中,CO法拉第效率与载量呈现火山型曲线关系,-0.89 V时载量为20wt%的Pd/C催化剂达到最高的CO法拉第效率(91.2%). 生成CO的几何电流密度随着钯载量的增加而增加,但CO转换频率具有相反的趋势,载量为2.5wt%的Pd/C催化剂具有最高的转换频率. 这种载量对CO₂电化学还原反应活性和选择性的影响主要由活性位的数量、反应动力学、中间物种的稳定性以及反应物、中间物种和产物的传质过程等共同决定.     

三通道气相色谱法监测大气中CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)北大核心CSCD

我国正处于“碳达峰、碳中和”的关键时期,准确认识我国温室气体浓度时空格局以及变化对于评估“碳达峰”和“碳中和”行动成效非常重要。当前我国近地面温室气体高精度监测主要依赖进口的光学监测主机,单台仪器成本高且监测要素有限。为此,该研究基于传统的气相色谱法,自主设计了一套三通道气相色谱分析系统,在单台仪器上实现了5种主要长寿命温室气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))的高精度监测。对该系统的精密度、线性响应情况和准确度进行的针对性测试实验表明系统检测性能满足世界气象组织/全球大气观测(WMO/GAW)质控标准。针对环境浓度的CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)的连续分析精密度分别达0.08%、1.90%、0.05%、0.08%、0.66%。准确度测试中,5种气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))使用回归方程计算所得值与标称摩尔分数间的偏差分别达0.15×10-9、0.20×10-9、0.37×10-6、0.35×10-9、0.02×10-12(摩尔分数),CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)仪器响应值与标称摩尔分数的线性拟合相关系数(R2)均为0.9999,线性拟合残差和准确度基本达到WMO/GAW拓展质控目标。该系统对杭州城区大气温室气体在线连续监测结果显示,2021年5~7月期间大气CH_(4)、CO、CO_(2)和N_(2)O呈明显的日变化特征,主要受人为活动影响。综合测试和试运行结果表明,该研发系统具备良好的精密度、准确度、线性和稳定性,与目前国内广泛进口的仪器相比,具有技术自主可控、运行成本更低、自动化水平更高等优势,能满足多种温室气体在线监测研究的需求。     

Generation of intense secondary pulsed molecular beams of high kinetic energy controllable by a powerful IR laser

A method for generation of intense secondary pulsed molecular beams and beams of radicals of high kinetic energy controllable by a powerful IR laser is described. A pressure shock (shock wave) is used as a source of secondary beams. The pressure shock is formed in interaction between an intense pulsed supersonic molecular beam (or flow) and a solid surface. The characteristics of the secondary beams were studied. Their intensities and the degree of gas cooling in them were shown to be comparable with the corresponding characteristics of the unperturbed primary beam. The acceleration of molecules in the secondary beam is achieved due to vibrational excitation of them by high-power IR laser pulse in the pressure shock and subsequent vibrational to translational (V–T) relaxation, which occurs when a gas expands through the orifice into a vacuum. Intense [10²⁰ molecules/(sr s)] beams of SF₆ and CF₃I molecules with kinetic energies approximately equal to 1.5 and 1.2 eV, respectively, were generated in the absence of carrier gases. The SF₆ molecular beams with kinetic energies approximately from 2.5 to 2.7 eV with carrier gases H₂, He and CH₄ (SF₆/carriergas=1/10) were obtained. The possibility of generation of intense beams of cold radicals by this method is demonstrated. The intense beams of cold and accelerated CF₃ radicals were generated when the CF₃I molecules in the shock were dissociated by high-power CO₂ laser radiation. The spectral and energetic characteristics of acceleration of SF₆ and CF₃I molecules in the secondary beams were studied. The optimal conditions were found for obtaining high-energy molecules.     

神府烟煤快速热解特性研究

利用高频电炉对神府煤进行快速热解,研究了不同热解温度和停留时间下,固相和气相产物的性质。结果表明,煤焦的失重率及真密度随温度升高和时间的延长而增长。红外光谱结果表明,热解过程中,煤中含氢/含氧官能团分解,生成H₂、CO、CO₂、CH₄等气体,并且其分解程度随温度的升高和时间的延长而加深。气相产物中H₂和CO的释放量随温度的升高和时间的延长而增加,而CO₂和CH₄存在释放量的峰值。气相产物随温度的升高和时间的延长而增多,导致高温煤焦出现大量的孔隙和裂缝。     

Supported carbon molecular sieve membranes based on a phenolic resin

The preparation of a composite carbon membrane for separation of gas mixtures is described. The membrane is formed by a thin microporous carbon layer (thickness, 2 μm) obtained by pyrolysis of a phenolic resin film supported over a macroporous carbon substrate (pore size, 1 μm; porosity, 30%). The microporous carbon layer exhibits molecular sieving properties and it allows the separation of gases depending on their molecular size. The micropore size was estimated to be around 4.2 Å. Single and mixed gas permeation experiments were performed at different temperatures between 25°C and 150°C, and pressures between 1 and 3.5 bar. The carbon membrane shows high selectivities for the separation of permanent gases like O₂/N₂ system (selectivity≈10 at 25°C). Gas mixtures like CO₂/N₂ and CO₂/CH₄ are successfully separated by means of prepared membranes. For example, the membrane prepared by carbonization at 700°C shows at 25°C the following separation factors: CO₂/N₂≈45 and CO₂/CH₄≈160.     

The electronic quenching rates of NO(AΣ, v=0–2)

The electronic quenching rates of NO(A²Σ⁺, v^′=0–2) are measured for the gases He, Ar, Xe, N₂, O₂, CO₂, N₂O, and SF₆. The variations of the fluorescence intensity were measured for the (0,0), (1,0), and (2,0) bands of the γ band system when the quencher gases were added. The quenching rates were determined by using the Stern–Volmer plots with the known radiative lifetimes of the excited states. The electronic quenching rate constants are fast for the group of gases of O₂, CO₂, N₂O, and SF₆, whose quenching rate constants are in the order of 10⁻¹⁰ cm³/s. The quenching rate constants are slow for the group of gases including He, Ar, Xe, and N₂ whose rate constants are in the order of 10⁻¹⁴ cm³/s. For the slow group, the quenching rate constants increase rapidly for v^′=2 compared with those of v^′=0 and 1.

The charge transfer model and collision complex model are used to understand the quenching mechanism. For the fast group which mainly consists of gases with positive electron affinities, the charge transfer model adequately describes the mechanism. For the slow quenching group, a theoretical background is provided by consider the coupling of initial and final states in the complex potential surfaces.     

三氟甲基磺酰氟绝缘介质理化特性的分子动力学模拟

采用分子动力学模拟方法, 研究了新型绝缘介质三氟甲基磺酰氟(CF₃SO₂F)的理化特性, 为高压电气设备应用CF₃SO₂F替代SF₆气体提供了理论依据. 基于量子化学计算的分子结构、 内转动、 偶极矩和振动频率等优化设计了mPCFF力场模型, 计算了243~323 K温度范围内CF₃SO₂F的各种气-液相平衡性质(饱和蒸汽压、 密度、 热容、 蒸发焓和临界参数等)与关键输运特性(扩散系数、 介电常数、 黏度和热导率等)基础参数, 并考察了CF₃SO₂F与N₂或CO₂形成混合气体的理化特性. 通过对比SF₆以及C4/CO₂混合环保绝缘气体, 针对混合比、 液化温度、 扩散和热导等因素提出了CF₃SO₂F的电气设备应用建议.     

Some aspects of calcium sulphite reduction with carbon monoxide

The non-isothermal reductive decomposition reaction of crystalline CaSO₃·0.5H₂O and anhydrous CaSO₃ under CO, CO₂ and CO-CO₂ gas mixtures at the two heating rates of 25°C min⁻¹ and 6°C min⁻¹ up to 900°C, respectively, was investigated employing thermogravimetric analysis, X-ray powder diffraction, IR spectroscopy and continuous SO₂ measurement by on-line fluorescence spectroscopy. During the heating process the reaction involved a multistage weight loss, in both cases, with a corresponding multistage SO₂ release. The multistage weight loss and the corresponding SO₂ release were presumed to be the consequence of different sequential reactions taking place along with the direct reduction of CaSO₃ to CaS, including the formation and decomposition of CaCO₃ and CaSO₄, respectively. The corresponding SO₂ evolution was found to be considerably lower at slow heating rates. In the presence of additional CO₂, the SO₂ release was increased and the highest SO₂ concentration was found for a feed-gas mixture of 70% CO₂ and 30% CO, and also in pure CO₂. The CaCO₃ product also increased with increasing CO₂ concentration. The possible reaction pathway is discussed.     

添加气对非平衡等离子体转化低碳烷烃的影响

在常压下, 研究了添加气的种类(N₂, He, Ar, H₂, NH₃, CO和CO₂)对介质阻挡放电低碳烷烃(甲烷、 乙烷和丙烷)转化制低碳烯烃的影响. 结果表明, 以甲烷或乙烷为原料时, N₂, He, Ar和CO的引入有利于提高原料的转化率和总烯烃的选择性; 而CO₂, H₂和NH₃的引入对甲烷、 乙烷的转化率无明显影响, 但H₂和NH₃的引入会使总烯烃的选择性显著降低. 以丙烷为原料时, 所研究的添加气均可提高丙烷的转化率, 而只有CO的引入可提高总烯烃选择性. 综上所述, 80%(摩尔分数) CO添加量最有利于低碳烷烃转化成低碳烯烃, 对应的甲烷、 乙烷和丙烷的转化率分别提高了14.4%, 17.6%和42.8%, 总烯烃的选择性分别提高了19.9%, 25.0%和11.9%. 以CH₄为例, 通过对放电电流波形和等离子体区物种的发射光谱(OES)研究发现, 引入CO能显著增加等离子体的电子密度, 并且体系中出现激发态O^*物种(777.5和844.7 nm), 这种O^*物种能够促进C-H键的断裂, 有利于烯烃的生成. 因此, 等离子体区电子密度的增加和激发态O^*物种的出现可能是CH₄-CO体系中CH₄有效转化的主要原因.     

过渡金属催化CO2/H2参与的羰基化研究进展

Ever-increasing energy demands due to rapid industrialization and urban population growth have drastically reduced petroleum reserves and increased greenhouse-gas production, and the latter has consequently contributed to climate change and environmental damage. Therefore, it is highly desirable to produce fuels and chemicals from non-petroleum feedstocks and to reduce the atmospheric concentrations of greenhouse gases. One solution has involved using carbon dioxide (CO₂), a main greenhouse gas, as a C1 feedstock for producing industrial fuels and chemicals. However, this requires high energy input from reductants or reactants with relatively high free energy (e.g., H₂ gas) because CO₂ is a highly oxidized, thermodynamically stable form of carbon. H₂ can be generated through water photolysis, making it an ideal reductant for hydrogenating CO₂ to CO. In situ generation of CO such as this has been developed for various carbonylation reactions that produce high value-added chemicals and avoid deriving CO from fossil fuels. This is beneficial because CO is toxic, and when extracted from fossil fuels it requires tedious separation and transportation. This combination of CO₂ and H₂ allows for functional molecules to be synthesized as entries into the chemical industry value chain and would generate a carbon footprint much lower than that of conventional petrochemical pathways. Based on this, CO₂/H₂ carbonylations using homogeneous transition metal-based catalysts have attracted increasing attention. Through this process, alkenes have been converted to alcohols, carboxylic acids, amines, and aldehydes. Heterogeneous catalysis has also provided an innovative approach for the carbonylation of alkenes with CO₂/H₂. Based on these alkene carbonylations, the scope of CO₂/H₂ carbonylations has been expanded to include aryl halides, methanol, and methanol derivatives, which give the corresponding aryl aldehyde, acetic acid, and ethanol products. These carbonylations revealed indirect CO₂-HCOOH-CO pathways and direct CO₂ insertion pathways. The use of this process is ever-increasing and has expanded the scope of CO₂ utilization to produce novel, high value-added or bulk chemicals, and has promoted sustainable chemistry. This review summarizes the recent advances in transition-metal-catalyzed carbonylations with CO₂/H₂ and discusses the perspectives and challenges of further research.     

Evaluation of carrier gases for use in high-field asymmetric waveform ion mobility spectrometry

Effects of carrier gas type (N₂, O₂, CO₂, N₂O, and SF₆) on changes in the ratio of high- to low-field ion mobility, K_h/K, of cesium, gramicidin S, tetrahexylammonium, heptadecanoic acid, and aspartic acid in fields of up to 67 Td are presented. The theory of the mobility of ions at high E/N in different gases is discussed. Plots of K_h/K as a function of the ionic energy parameter, E/N, for the five ions in each of the gases were derived from experimental data collected using a high-field asymmetric waveform ion mobility spectrometer. The change in the ratio of high- to low-field ion mobility of cesium in carrier gases of O₂ and N₂ showed excellent agreement with literature values. The behavior of cesium in O₂ and N₂ is used to illustrate that the ratio K_h/K as a function of effective temperature is invariant with gas type as long as the well depth of the interaction potential significantly exceeds thermal energy. From these results, it appears that the well depth of the interaction potential of the heavier ions studied here, including gramicidin S, tetrahexylammonium, and heptadecanoic acid, with bath gases such as N₂ and O₂, is shallow relative to thermal energy.