活性氧缺位铁酸铜的制备及其在热化学分解水制氢中的应用

热化学循环分解水制氢是近年来国际上核能制氢计划的研究热点课题,除美国通用原子能公司（GA）发明的碘硫（IS）循环和东京大学发明的UT-3循环外,作为最简单的热化学循环制氢体系,氧化物体系热化学分解水制氢近年来受到了国际上的广泛关注．采用化学共沉淀法制备了具有尖晶石结构的铁酸盐,经高温煅烧使其形成了初始分解温度仅为839Y3的高活性氧缺位铁酸铜（CuFe2O4-δ）,设计并开发了两步骤热化学循环制氢反应试验装置．利用XRD,DTA—TG,AAS和GC等分析方法和实验技术,对制备出的氧缺位铁酸铜样品的结构、性质、化学组成及氧缺位程度占值进行了详细的研究,并对CuFe2O4-δ分解水制氢过程和循环性能进行了探讨和研究．     

金属氧化物两步热化学循环分解水制氢*

金属氧化物两步热化学循环分解水制氢技术集太阳能储备与氢能制备于一体,是当前新能源研究和开发领域的热点之一。本文介绍了该技术制氢原理,综述了其关键材料金属氧化物体系和太阳能反应器的研究进展,分析了制约该技术规模化应用的“瓶颈”因素。最后,对近年出现的基于金属氧化物两步热化学循环分解水制氢的两步蒸汽重整新工艺的原理和金属氧化物材料研究进行了介绍,并对该领域的发展趋势进行了展望。     

吸收增强式甲烷水蒸气重整制氢循环反应模拟

吸收增强式甲烷水蒸气重整制氢反应可以生成高浓度的H2和较低浓度的CO、CO2。研究建立了考虑钙基吸收剂活性下降对吸收增强式甲烷水蒸气重整制氢过程影响的多次循环反应模型,在实验数据验证的基础上,计算了三种吸收剂活性下降特性对吸收增强式重整制氢过程的影响。结果表明,对于石灰石吸收剂,产生高纯H2的时间随循环次数的增加而急剧下降;白云石循环反应活性提高,产生高纯H2的时间随循环次数的增加而缓慢下降;CaO/Ca12Al14O33的循环使用次数明显大于石灰石和白云石。     

新型节能CO2零排放工艺——化学循环燃烧技术

介绍了一种新型节能CO2零排放工艺——化学循环燃烧技术中几个热点研究问题,包括热力学分析、氧载体及反应器的设计与选用,探讨了化学循环燃烧技术在我国乃至国际清洁煤燃烧领域的发展前景.还对由化学循环概念发展而来的化学循环重整过程以及水分解制氢过程做了简要的概述,最后展望了化学循环燃烧技术的研究发展趋势.     

分解水制氢的KNO3—I2循环之研究：Ⅲ.代替电解反应的一个子循环

本文提出了一个硫酸中间盐子循环用以代替分解水制氢的KNO_3-I_2混合循环中的电解反应,从而使原混合循环变为一个纯热化学循环。     

基于碘离子选择性电极的流动注射分析系统构建

碘硫(IS)热化学循环分解水是目前最有前景的核能制氢技术.在IS循环研究中,I-浓度的在线分析对于实现过程反应条件的监测控制以及进行有关反应动力学研究非常重要.以碘离子选择性电极为检测器,针对IS循环物料组成体系组装了一套流动注射分析系统,考察了样品温度、氢离子浓度、离子强度等因素对电极性能的影响,对FLA装置的栽流流...     

热化学碘硫循环中Bunsen反应

碘硫循环;制氢;Bunsen反应;分离特性     

新型节能CO2零排放工艺——化学循环燃烧技术

介绍了一种新型节能CO₂零排放工艺——化学循环燃烧技术中几个热点研究问题,包括热力学分析、氧载体及反应器的设计与选用,探讨了化学循环燃烧技术在我国乃至国际清洁煤燃烧领域的发展前景。还对由化学循环概念发展过来的化学循环重整过程以及水分解制氢过程做了简要的概述,最后展望了化学循环燃烧技术的研究发展趋势。     

甲醛催化制氢的研究进展

氢有较高的能量密度,其能量转换过程可循环、零污染,是未来替代传统化石燃料的理想能源载体.甲醛相较于其它的氢载体,具有可规模制备、来源广泛、安全性高、易于输运、储存和转化的特点,已逐渐成为一种新的制氢原料.此外甲醛制氢技术还可以应用于其它对环境有一定毒性的有机化合物转变为清洁的氢的过程.我们较全面的总结了甲醛的工业化制备、催化转化制氢和催化剂的研究发展历程,详细介绍了近年来在相关领域的研究成果,分析对比了各种甲醛催化制氢技术的特点,并对未来甲醛制氢的发展前景进行了展望.     

PdAg/MIL-101(Fe)催化NaBH4水解制氢

将PdAg纳米颗粒负载到MIL-101(Fe)上作为硼氢化钠水解制氢的催化剂。采用XRD、TEM、HRTEM、XPS、SEM和EDS等方法对催化剂PdAg/MIL-101(Fe)的结构进行了表征。PdAg/MIL-101(Fe)在硼氢化钠水解制氢中表现出较高的催化活性,在温和的条件下水解制氢最大速率为2.60 L·min^–1·g_cat.^–1。详细研究了反应温度、催化剂用量、氢氧化钠和硼氢化钠浓度对该催化反应的影响规律。结果发现,制氢速率很大程度上依赖于反应温度,随着反应温度的升高,制氢速率明显增加,制氢的表观活化能为54.89 kJ·mol^–1。该催化剂重用性能好,5次循环后仍能保持活性。     

Polymeric Materials Derived from Vanillic Acid

Film and fibrous materials derived from vanillic acid, one of promising products from processing of industrial lignin, were prepared and characterized. Thermochemical reactions of degradation and carbonization of films and fibers of vanillic acid polyesters and polyamides were considered, and the main relationships of thermal transformations of the materials were revealed.     

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the hybrid sulfur (HyS) process which uses a sulfur dioxide-depolarized electrolyzer (SDE) to produce the hydrogen. Testing examined the activity and stability of platinum and palladium as the electrocatalyst for the SDE in highly concentrated sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by the concentration of the sulfuric acid electrolyte.     

Enthalpy Characteristics of Solution and Solvation of CuCl2 in Water-Acetonitrile Mixtures at 298.15 K

Thermochemical characteristics of solution of copper(II) chloride were found from calorimetricdata, values describing solvation processes in a water-acetonitrile mixed solvent were calculated for theentire range of compositions. Enthalpy characteristics of solvation of individual Cu^{2 +} ions in water-aceto-nitrile mixtures were found and analyzed.     

On the solid state reactions in the system MnSiN

The reaction processes involving the formation and decomposition of manganese silicon nitride MnSiN₂ have been investigated. Thermochemical analysis in nitriding, inert and oxidizing atmospheres was carried out for this nitride and the appearing intermediate phases. The investigation was performed using TG, DTA and DTG techniques in the temperature range 25–1500°C.     

Extrapolating H-atom transfer rate constants via thermochemical kinetics: The effect of tunneling

One of the important applications of chemical kinetics is the attempt to understand complex processes through kinetic modeling. This process frequently requires that rate constants be obtained by extrapolation of data either to higher or lower temperatures than the experimental, or by estimation or correlation with such data. Thermochemical kinetics combined with conventional transition state theory forms a framework from which this may be done. However, rate data for H transfer reactions may have a significant contribution from tunneling. In this work, a one dimensional approach to tunneling, consistent with conventional transition state theory, is taken to show how tunneling affects the extrapolation and correlation of rate constants in thermochemical kinetics. It is concluded that extrapolation and correlation are both quite good even when tunneling comprises 80% of the reaction. However, this is not without limitations, which are discussed. © 1993 John Wiley & Sons, Inc.     

Mechanism of white phosphorus activation by three-coordinate molybdenum(III) complexes: a thermochemical, kinetic, and quantum chemical investigation

White phosphorus (P(4)) reacts with three-coordinate molybdenum(III) trisamides or molybdaziridine hydride complexes to produce either bridging or terminal phosphide (P(3)(-)) species, depending upon the ancillary ligand steric demands. Thermochemical measurements have been made that place the MoP triple bond dissociation enthalpy at 92.2 kcal.mol(-)(1). Thermochemical measurements together with computational analysis rule out simple P-atom abstraction from P(4) as a step in the phosphorus activation mechanism. Kinetic measurements made by the stopped-flow method show that the reaction between the monomeric molybdenum complexes and P(4) is first-order both in metal complex and in P(4). Cyclo-P(3) complexes can be obtained when ancillary ligand steric demands are small, but kinetic measurements rule them out as monometallic intermediates in the P(4) activation mechanism. Also studied by calorimetric, kinetic, and in one case variable-temperature NMR methods is the process of mu-phosphide bridge formation. Post-rate-determining steps of the P(4) activation process were examined in a search for minima on the reaction's potential energy surface, leading to the proposal of two plausible, parallel, bimetallic reaction channels.     

Shelf-Life Studies on B-Stage Novolac Epoxy Glass Mica Tapes

Activation energy for the curing process of epoxy glass mica tape has been experimentally determined from differential scanning calorimetric measurements and found to be 20 kcal/ mol. Thermochemical calculation shows that the rate controlling step is the dissociation of the C-O bond in the epoxide leading to ring opening and its subsequent reaction with amine hardener. Shelf life has been determined from the measurement of the enthalpy loss corresponding to the curing during the aging process. The kinetics of the aging process also yields an activation energy of 20 kcal/mol which corresponds to the slow curing of the epoxy resin.     

A kinetic model for pyrolysis of CF2HCl

Thermal decomposition of CF₂HCl has been modeled using 2,269 thermally activated reactions and 63 chemically activated processes. Thermochemical properties for the species involved are calculated using statistical mechanics and group contribution theory, and reaction rate constants are determined using transition state theory. The theoretical predictions, obtained without fitting any parameter values, afree closely with available experimental data. Also, the reactions that control the distribution of reaction products are identified, and this, in turn, permits simplification of the reaction set. Sensitivity studies show that uncertainties in the calculations do not alter the predicted trends in behavior or the main reaction pathways. © 1995 John Wiley & Sons, Inc.     

Thermochemical Transformations in the Twelve-Salt Six-Component Reciprocal System Na,K,Ca,Ba∥F,SO4,WO4

Thermochemical characterization of the twelve-salt system Na,K,Ca,Ba∥F,SO₄,WO₄ (a 4∥3 system) and the four nine-salt five-component reciprocal subsystems is presented. A comparison of thermochemical relationships is carried out for these nine-salt systems, and the internal structural thermochemical transformations of exchange-reaction stages between all these systems are considered. The effect of a reaction stage on the final product yield is considered for sample chemical reactions. The thermochemical structure of basal tetrahedra of the singular star in the twelve-salt system is studied, and relationships are derived between various models of the system (salt-node indices in the matrix, reaction stages, geometrical figures) and chemical processes that occur in the system. These relationships can be used in experimental design.