氢气在共价有机骨架材料中的吸附机理

共价有机骨架材料(COFs)是一种新型的储氢材料。采用密度泛函理论研究了COFs的7种主要团簇对H₂的吸附机理,计算中选用GGA/PBE泛函。结果表明,当H₂垂直接近时,团簇中心苯环为最优先吸附位,当H₂平行接近时,硼氧环的中心以及氧原子上为最优先的吸附位。有机链团簇C原子数目的增加有利于对氢气的吸附,多个H₂分子在COF-10和COF-105团簇的吸附主要属于协同吸附。对COFs进行碱金属(Li、Na、K)掺杂和官能团替代(甲基-CH₃、巯基-SH、氨基-NH₂)改性,发现H₂吸附能得到显著提高,说明改性是提高COFs材料H₂吸附能力的有效途径。     

低温相变蓄热材料性能研究及在移动蓄热装置中应用

基于当前对KAl(SO₄)₂·12H₂O蓄热性能研究较少且很少有蓄热装置应用KAl(SO₄)₂·12H₂O作为相变蓄热材料的问题。对KAl(SO₄)₂·12H₂O的制备和蓄热性能进行了总结以及热力学性能分析,得出环境温度及初始温度对相变材料?效率影响较小,终止温度对?效率影响较大;当初始温度为328K,环境温度288K时,最佳终止温度为370K。同时,针对KAl(SO₄)₂·12H₂O应用于移动蓄热装置进行数值模拟,得到液相率、温度随时间的变化曲线。本文研究表明KAl(SO₄)₂·12H₂O是一种性能良好的低温蓄热材料。     

五元体系NaBr-KBr-MgBr2-CaBr2-H2O在298.15 K下的空间立体相图研究

为合理开发四川盆地富溴地下卤水资源,对五元体系NaBr-KBr-MgBr₂-CaBr₂-H₂O进行了298.15 K条件下完整的相平衡与相图的研究。根据实验测定的溶解度数据,绘制出了完整的空间立体相图,NaBr·2H₂O、MgBr₂·6H₂O和CaBr₂·6H₂O三种盐饱和面的干基投影相图,以及相应的含水量图。研究结果表明该五元体系在298.15 K下的空间立体相图中包含有十条单变量曲线、三个共饱点和六个结晶区（KBr结晶区、NaBr结晶区、NaBr·2H₂O结晶区、MgBr₂·6H₂O结晶区、CaBr₂·6H₂O结晶区、KBr·MgBr₂·6H₂O结晶区）。其中KBr结晶区最大,CaBr₂·6H₂O结晶区最小,表明在该体系中CaBr₂·6H₂O的溶解度最大,KBr溶解度最小。     

一种低能耗捕集CO2煤基甲醇和电力联产过程设计

传统的煤制甲醇过程所需合成气的氢碳比为2.1左右,而煤气化粗合成气氢碳比仅为0.7左右,因此需要将部分合成气进行变换来调节氢碳比。然而,变换气与未变换气混合后使得CO₂浓度降低,从而导致CO₂捕集能耗增加。提出了一种低能耗捕集CO₂煤基甲醇和电力联产过程。新联产过程中部分粗合成气首先经过变换,将CO转变为H₂和CO₂,CO₂浓度提高,在此时进行CO₂捕集可实现捕集能耗的降低。经CO₂捕集后,得到富H₂气体,富H₂气体分流后与另一部分煤气化粗合成气混合调节甲醇合成的氢碳比。对新的过程进行了建模、模拟与分析。结果表明相比传统的带CO₂捕集的煤制甲醇和IGCC发电过程,新的联产过程的能量节约率可达到16.5%,CO₂捕集能耗下降30.3%。     

ZnO修饰的不锈钢网支撑体上ZIF-8膜的制备

ZIF-8因具有0.34 nm的孔道直径而被认为是最具应用前景的气体分离膜材料之一。不锈钢网（SSN）作为分离膜的支撑体具有价格低廉、易于裁剪、厚度薄等优点。采用水热法在SSN表面生长ZnO缓冲层,以ZnO修饰的SSN（ZnO/SSN）为支撑体制备ZIF-8膜。采用X射线衍射（XRD）和扫描电子显微镜（SEM）对合成的ZIF-8膜进行表征,并进行了气体渗透性能测试,结果表明,在ZnO颗粒修饰后的SSN支撑体上无需活化可制备出单一物相、无缺陷的ZIF-8膜;在室温（298 K）下,ZIF-8膜的H₂/CO₂、H₂/N₂、H₂/CH₄的理想分离系数分别为7.3、9.2、12.4;在150℃,ZIF-8膜的渗透性能稳定。     

氢液化与低温高压储氢技术发展现状

H₂来源广泛、清洁无碳，是未来重要的清洁二次能源载体，在世界能源格局中占重要地位。H₂低温致密化技术可大幅提高储氢密度，有效解决H₂低密度、低沸点带来的大规模储运难题。综述了氢液化与低温高压储氢2种低温储氢技术的发展现状，对比了各类低温储氢流程的性能和特点，总结了未来发展方向，为H₂储运技术的发展提供参考。其中低温液态储氢(氢液化)的储氢密度高且储氢压力低，是目前主流的大规模氢储运方法之一；低温高压储氢则可达到与液氢接近的储氢密度，且本征能耗低、无需正仲氢转化，极具发展潜力；而采用以混合工质节流制冷循环为代表的闭式低温制冷循环替代液氮对H₂进行预冷或冷却，可显著降低H₂低温致密化能耗，是2种低温储氢技术的重要发展趋势。     

四元体系NaCl+NaBO2+Na2CO3+H2O 298.15 K 相平衡研究

柴达木盐湖中具有丰富的盐湖离子,对其中的一个四元体系水盐相图开展研究,采用等温溶解平衡法开展了298.15 K时四元体系NaCl+NaBO₂+Na₂CO₃+H₂O相平衡研究,测定了体系平衡液相组成及密度和折光率,绘制了四元体系NaCl+NaBO₂+Na₂CO₃+H₂O 298.15 K的相图及相应的物化性质图。研究发现NaCl+NaBO₂+Na₂CO₃+H₂O四元体系298.15 K 时包含2个共饱点（E₁、E₂）、5条溶解度曲线（AE₁、BE₁、CE₂、DE₂、E₁E₂）、4个结晶区（NaCl、NaBO₂·4H₂O、Na₂CO₃·7H₂O、NaCl·NaBO₂·2H₂O）。其中三元体系NaCl+NaBO₂+H₂O在298.15 K下产生了复盐NaCl·NaBO₂·2H₂O,通过研究发现该四元体系NaCl+NaBO₂+Na₂CO₃+H₂O在298.15 K下也具有NaCl·NaBO₂·2H₂O复盐区。     

298 K和323 K条件下五元体系NaBr-KBr-MgBr2-CaBr2-H2O相平衡研究

针对四川盆地地下卤水富含钾、溴资源的特点,采用等温溶解平衡法研究了五元体系NaBr-KBr-MgBr₂-CaBr₂-H₂O在298 K和323 K时的相平衡关系,测定了该五元体系在相应温度条件下平衡溶液的溶解度,根据相平衡实验数据绘制相应的干盐相图(KBr饱和)。研究结果表明：该五元体系在298 K和323 K条件下(KBr饱和)均有复盐生成,其中298 K温度下有复盐KBr·MgBr₂·6H₂O生成,相图中含有两个共饱点,五条单变量曲线和四个结晶区(KBr·MgBr₂·6H₂O、NaBr·2H₂O、NaBr、CaBr₂·6H₂O的结晶区);323 K温度下有两种复盐KBr·MgBr₂·6H₂O、2MgBr₂·CaBr₂·12H₂O生成,相图中含有三个共饱点,七条单变量曲线和五个结晶区(KBr·MgBr₂·6H₂O、NaBr·2H₂O、NaBr、CaBr₂·4H₂O、2MgBr₂·CaBr₂·12H₂O的结晶区)。同时,对该五元体系在两个不同温度下的相图、KBr图以及水含量图进行了对比分析。     

四元体系LiB5O8+NaB5O8+KB5O8+H2O在298.15K实验与理论预测相平衡研究

采用等温溶解平衡法研究了四元体系LiB₅O₈ + NaB₅O₈ + KB₅O₈ + H₂O在298.15 K下的相平衡。实验测定了该体系在298.15 K下的固液相平衡溶解度和物理性质（密度和折射率）,基于实验溶解度绘制了四元体系的干盐相图、水图和物理性质组成图。在该四元体系的干基图中,有一个共饱点（LiB₅O₈·5H₂O + NaB₅O₈·5H₂O + KB₅O₈·4H₂O）、3条单变量溶解度曲线和3个单盐结晶区（LiB₅O₈·5H₂O、NaB₅O₈·5H₂O和KB₅O₈·4H₂O）。该体系在298.15 K下没有复盐和固溶体生成,属于简单四元水溶液体系。结合三元体系溶解度,拟合获得了3种碱金属五硼酸盐的单盐参数和三离子混合作用参数;应用Pitzer及其扩展的HW模型对溶解度进行预测,预测值与实验值吻合较好,表明获得的Pitzer参数可靠。研究结果可为碱金属五硼酸盐分离纯化提供理论基础。     

基于Langmuir-Hinshelwood动力学解析O2/CO2/H2O气氛下烟煤焦反应机理

流化床富氧燃烧湿烟气循环兼具经济与环保优势。湿烟气循环（O₂/CO₂/H₂O）条件下煤焦与O₂、CO₂及H₂O的反应同时发生。为探究O₂/CO₂/H₂O气氛下煤焦-O₂、煤焦-CO₂、煤焦-H₂O反应间的相互作用机制,在自制高精度热重实验装置上系统考察了O₂、CO₂、H₂O及其混合气氛下,典型烟煤焦在900℃的反应特性。基于吸附和脱附原理的Langmuir-Hinshelwood（L-H）机理性模型分别计算了烟煤焦与O₂、CO₂和H₂O反应的动力学参数。通过采用单独活性位点与竞争活性位点两种假设分析了O₂/CO₂、O₂/H₂O和CO₂/H₂O气氛下烟煤焦-O₂、烟煤焦-CO₂和烟煤焦-H₂O两两反应间的作用机制,揭示了H₂O分子优先吸附于烟煤焦表面活性位点,O₂分子次之,而CO₂分子相对滞后。O₂/CO₂/H₂O气氛下烟煤焦-O₂、烟煤焦-CO₂、烟煤焦-H₂O反应表现出部分竞争反应活性位点,传统的单独活性位点与竞争活性位点假设均无法准确描述其反应速率特性。基于H₂O分子优先,O₂分子次优先吸附的原理,建立了O₂、CO₂、H₂O混合气氛下煤焦反应速率L-H动力学方程,方程计算结果与实验值良好吻合。研究结果为深入分析煤焦颗粒流化床富氧燃烧特性及构建可靠、准确的燃烧反应模型提供了理论支撑。     

Ferroelasticity and ferroelectricity in betaine arsenate

Single crystals of betaine arsenate, an addition compound of the amino acid betaine with H₃AsO₄, were investigated by dielectric, optical, caloric, and X-ray methods. At room temperature betaine arsenate is ferroelastic with two different monoclinic domains. This state seems to disappear at 411 K. Below T_c = 119 K the ferroelastic domains show a ferroelectric behaviour with a spontaneous polarization P_s = 2μC/cm² at T = T_c - 35 deg.     

Mechanochemical reaction between metals and liquid hydrocarbons Formation of V−, NB− and TA hydrides

Metal hydrides have been produced by the H₂ gas charging method in the past. This method is based on the adsorption and the dissociation of H₂ gas. But the high temperature, the high gas pressure or the complicated activation treatments are needed on the operations. The new production method to yield V-, Nb- and Ta hydrides, which is based on the use of the high reactivity of the fresh surface of metals and the dehydrogenation of liquid hydrocarbons, is introduced here. The fresh surfaces can be created by the continuous mechanical milling of metal powders. Metal hydrides were obtained at room temperature and at 1 atm.     

Solubility and mass transfer of H2, CH4, and their mixtures in vacuum gas oil: An experimental and modeling study

In this work, the solubility data and liquid-phase mass transfer coefficients of hydrogen (H₂), methane (CH₄) and their mixtures in vacuum gas oil (VGO) at temperatures (353.15-453.15 K) and pressures (1-7 MPa) were measured, which are necessary for catalytic cracking process simulation and design. The solubility of H₂ and CH₄ in VGO increases with the increase of pressure, but decreases with the increase of temperature. Henry's constants of H₂ and CH₄ follow the relation of ln H=-413.05/T + 5.27 and ln H=-990.67/T + 5.87, respectively. The molar fractions of H₂ and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients. The results showed that with the increase of pressure, the liquid-phase mass transfer coefficients increase. Furthermore, the solubility of H₂ and CH₄ in VGO was predicted by the predictive COSMO-RS model, and the predicted values agree well with experimental data. In addition, the gas-liquid equilibrium (GLE) for H₂ + CH₄ + VGO system at different feeding gas ratios in volume fraction (i.e., H₂ 85% + CH₄ 15% and H₂ 90% + CH₄ 10%) was measured. The selectivity of H₂ to CH₄ predicted by the COSMO-RS model agrees well with experimental data. This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.     

Synthesis of Ba2RCu4O8 (R = Y, Sm) Superconductors at Oxygen Pressure of 1 atm by Spray-Frozen/Freeze-Drying Method

Precursor powders for high- T_c Ba₂RCu₄O₈ (R = Y, Sm) superconductors were successfully prepared through spray-frozen/freeze-drying (SF/FD) of a mixed aqueous solution that included the respective compounds according to the stoichiometric composition. These SF/FD powders were used to obtain ceramic superconductors composed of single-phase orthorhombic Ba₂RCu₄O₈ (R = Y, Sm) by sintering at an oxygen pressure of 1 atm. Critical temperatures measured were 84 K and 76 K for Ba₂YCu₄O₈ and Ba₂SmCu₄O₈, respectively, comparable to the previously reported values for these superconductors prepared under high oxygen pressure (100 atm). The present result was assumed attributable to the highly homogeneous powders.     

Synthesis and H2 uptake of Cu2(OH)3Cl, Cu(OH)2 and CuO nanocrystal aggregate

Monodispersed Cu₂(OH)₃Cl nanoplatelets, Cu(OH)₂ nanowires, CuO nanoparticles and nanoribbons with a spherical morphology were synthesized using hydrothermal and heat-treatment reactions, and their H₂ storage characteristics were examined. The Cu₂(OH)₃Cl nanoplatelets particles formed immediately after mixing the reactant, which subsequently formed larger uniform spherical particles in the submicron range. This procedure highlights a practical strategy for producing spherical Cu(OH)₂ and CuO materials consisting of monodispersed nanocrystals. The spherical aggregates of Cu₂(OH)₃Cl nanoplatelets heat-treated at 473 K could reversibly store up to 2.35 wt.% H₂ at 38 bar and 293 K.     

Vanadium oxide nanotubes for selective catalytic reduction of NOx with NH3

Vanadium oxide(VO_x) nanostructures, synthesized by hydrothermal treatment using dodecylamine as template,were evaluated for the selective catalytic reduction of NO_xwith ammonia(NH_3-SCR). The effect of solvent type in the reaction mixture(Et OH/(Et OH + H_2O)) and time of hydrolysis was studied. The obtained materials were characterized by XRD, SEM, TEM and BET. The VO_xnanorods(80–120 nm diameter and 1–4 μm length) were synthesized in 25 vol% Et OH/(Et OH + H_2O) and the open-ended multiwalled VO_xnanotube(50–100 nm inner diameter, 110–180 nm outer diameter and 0.5–2 μm length) synthesized in 50 vol% Et OH/(Et OH + H_2O). VO_x nanotubes performed the superior NH_3-SCR activity under a gas hourly space velocity of 12,000 h-1at low temperature of 250 °C(NO_xconversion of 89% N_2 selectivity of 100%), while most of the developed Vanadia base catalysts are active at high temperature(N 350 °C). The superior NH3-SCR activity of VO_xnanotubes at low temperature is related to nanocrystalline structure, special nanotube morphology as well as high specific surface area.     

Thermodynamic analysis of steam reforming of glycerol for hydrogen production at atmospheric pressure

Thermodynamic chemical equilibrium analysis of steam reforming of glycerol(SRG)for selective hydrogen production was performed based on the Gibbs free energy minimisation method.The ideal SRG reaction(C₃H₈O₃+3H₂O→3CO₂+7H₂)and a comprehensive set of side reactions during SRG are considered for the formation of a wide range of products.Specifically,this work focused on the analysis of formation of H₂,CO₂,CO and CH4 in the gas phase and determination of the carbon free region in SRG under the conditions at atmospheric pressure,600 K–1100 K and 1.013×10⁵–1.013×10⁶ Pa with the steam-to-glycerol feed ratios(SGFR)of 1:5–10.The reaction conditions which favoured SRG for H₂ production with minimum coke formation were identifies as:atmospheric pressure,temperatures of 900 K–1050 K and SGFR of 10:1.The influence of using the inert carrier gas(i.e.,N₂)in SRG was studied as well at atmospheric pressure.Although the presence of N₂ in the stream decreased the partial pressure of reactants,it was beneficial to improve the equilibrium yield of H₂.Under both conditions of SRG(with/without inert gas),the CH4 production is minimised,and carbon formation was thermodynamically unfavoured at steam rich conditions of SGFR>5:1.     

Preferred orientation of the grains in the ceramics of high Tc-superconductors

Highly grain oriented YBa₂Cu₃O₇ and GdBa₂Cu₃O₇ ceramics are prepared by using the controlled calcining and sintering conditions. T_c and ▵T_c on such ceramics were ∼94K and 2K respectively.     

高稳定铪金属-有机骨架材料的合成及二氧化碳捕获性能

采用高温高浓度的溶剂热方法,合成了具有高结晶度的一种金属-有机骨架（metal-organic framework,MOF）材料UiO-66（Hf）,并发现该材料在沸水、酸碱等苛刻条件下具有非常好的化学稳定性。为了提高其对气体的吸附分离性能,进一步采用具有不同官能团的有机配体--氨基对苯二甲酸（H₂BDC-NH₂）、硝基对苯二甲酸（H₂BDC-NO₂）、溴对苯二甲酸（H₂BDC-Br）,设计合成了孔道表面具有不同化学性质的三种新型铪MOF材料,且这些材料与UiO-66（Hf）具有相同的拓扑结构。同时,气体吸附实验结果表明,极性基团的引入,尤其是氨基的引入,能极大提高材料对CO₂/N₂以及CO₂/CH₄体系的分离性能。这为以后应用于化工体系分离的新型多孔材料合成提供了理论指导。     

The role of oxygen vacancies during the decomposition of RhCl3/TiO2 precursor: study by XPS, IR, EPR and NMR.

Thermal reduction under ultrahigh vacuum or with H₂ of RhCl₃/TiO₂ precursors up to 773K has been studied either directly or after precalcination with O₂ at 773K. The evolution of rhodium and chlorine has been followed with the aid of XPS, EPR, IR ¹H-NMR and TPR/DTG for the different treatments. Ar⁺ sputtering has been used in combination with XPS to examine in detail the incorporation of chlorine to the TiO₂ support. A model is proposed which assumes the formation during the reduction process of oxygen vacancies (Vo) associated to Ti³⁺ species (i.e. (TiVo)_n³ⁿ⁺). These centers act promoting the reduction of Rh³⁺ to Rh^o and upon extensive reduction at 773K in H₂, as anchoring sites of Rh^o through interaction with exposed Ti³⁺ ions. Oxygen vacancies sites are also able to incorporate chlorine and hydrogen to form in the later case hydride, (Ti-H)³⁺, species that we have previously found to have a role in the SMSI state.