电厂废气中饱和水蒸气对活性炭变压吸附捕集CO2的影响

由于热电厂废气中含有高湿饱和水蒸气,选用疏水材料活性炭为吸附剂,利用真空变压吸附技术研究了活性炭分离电厂废气中水蒸气和二氧化碳的可行性和优越性,研究了水对CO₂捕集的影响。实验分析表明,水在活性炭上的“S”型等温吸附曲线有利于真空条件下被解吸。同时,圆锥模型描述了水蒸气在吸附床内的浓度分布。结果表明,即使水蒸气可以被活性炭吸附,但它的存在不影响CO₂的捕集。每个循环操作可在相对较短的解吸时间和较高的解吸压力下完成。实验中单床三步变压吸附工艺可以使CO₂回收率高达80%,CO₂纯度达43%。     

湿气源吸附碳捕集: CO2/H2O共吸附机制及应用

大型湿气源排放中普遍存在的水汽是制约吸附碳捕集规模化发展的重要挑战之一。H₂O的极性往往会导致吸附材料的CO₂捕集率降低甚至出现失效,也会造成捕集系统产生温降、压降等寄生损失,甚至形成设备腐蚀、吸附剂中毒等不利影响,最终额外能耗和成本大幅提高。为解决上述挑战,深入理解CO₂与H₂O共吸附过程的作用机制,据此开发成本合理、再生能耗低且对水气不敏感的高效CO₂吸附剂及吸附技术是实现湿气源下高效吸附碳捕集的重要途径。目前,由于分散在多个领域且各有侧重,关于H₂O对CO₂吸附影响的机制分析缺乏汇总与概括,难以形成相对统一的观点。本文针对CO₂与H₂O共吸附过程,从宏观与微观层面进行了详细综述。首先,基于共吸附机制的基础研究,依次介绍了竞争吸附、变湿吸附和呼吸效应领域的研究进展并进行了简要评价。其次,基于共吸附的应用研究,阐述了湿气源CO₂捕集技术的吸附剂研发与工艺改进两部分的现状及进展,也对不同湿气源下CO₂捕集水平进行了简要评价。最后,总结了目前研究中的不足之处并展望了未来的研究方向。本文将分散于各领域的CO₂与H₂O共吸附过程进行集中归纳、分析和对比,或可为湿气源碳捕集技术提供有效的指导。     

Li4SiO4对CO2捕集性能的实验研究

以Li₂CO₃和SiO₂为原料,通过高温固相合成法合成了CO₂捕集剂Li₄SiO₄,并用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)对所合成的材料在CO₂捕集前后的晶相变化以及微观结构进行了表征。通过热重分析仪(TGA)研究了Li₄SiO₄材料吸附CO₂的性能,并在小型热态实验台架上进行了CO₂热态捕集实验。实验结果表明,Li₄SiO₄对CO₂的捕集性能受Li₄SiO₄合成温度、CO₂的吸附温度以及气体中CO₂含量的影响,在700 ℃下制得的Li₄SiO₄具有最佳的CO₂吸附特性,最大吸附增量可达34%。Li₄SiO₄的吸附能力随着CO₂含量和吸附时间的增加而增加,当CO₂浓度分别为75%、67%、60%时,700 ℃ Li₄SiO₄对CO₂最大吸附量分别可达6.68 mmol/g、3.37 mmol/g、2.02 mmol/g (理论量8.33 mmol/g)。     

金属有机框架材料的制备及在吸附分离CO2中的应用

金属有机框架（MOFs）材料是当今的研究热点之一,是一类颇有潜力成为适用于CO₂吸附和分离的重要材料。本文从MOFs的发展及其所具有的特点、MOFs用于CO₂的吸附与分离所取得的突破性进展以及MOFs的传统合成及绿色制备方法三个方面展开论述。主要论述了MOFs适用于CO₂吸附的原理,及其相对于传统的CO₂吸附材料所具有的特点和优势,亦阐述了MOFs修饰与调变的方法。列出了MOFs用于单组分CO₂吸附及CO₂/CH₄、CO₂/N₂吸附分离的结果。同时,针对传统MOFs制备方法不适宜大规模CO₂捕集材料的生产,特别论述了机械化学合成法和新兴的潮湿矿物风化法,其均具有绿色化、无溶剂、低能耗和简单等特点,是一类较有研究价值和应用潜力的技术。随着温室效应和不可再生石化燃料的消耗等环境和能源问题的日趋严峻,研究及开发适用于CO₂捕集与封存技术的MOFs新材料迫在眉睫,且任重而道远。     

复杂烟气条件下太西活性焦脱除Hg0的实验研究

为了解复杂烟气条件下活性焦吸附剂的脱汞特性,利用汞渗透管和主要气体成分模拟复杂烟气,在实验室规模的固态吸附剂汞吸附效能测定系统上,进行了太西活性焦吸附单质汞的实验研究,并采用FT-IR对活性焦表面进行了光谱表征。结果表明,在活性焦表面存在各种含氧官能团;在CO₂/N₂/O₂/SO₂/Hg⁰烟气体系中,当SO₂加入量为400、855、1 520 mL/m³时,出口汞浓度分别为36、43、48 μg/m³,SO₂对系统吸附Hg⁰的能力有抑制作用;在CO₂/N₂/O₂/NO/Hg⁰烟气体系中,较低浓度的NO对Hg⁰脱除有抑制作用,而高浓度值的NO抑制作用减弱;在CO₂/N₂/O₂/NO/SO₂/Hg⁰烟气体系下,提高NO浓度对Hg⁰脱除有一定的促进作用,而提高SO₂浓度初期促进汞的脱除,后期则表现为抑制作用。     

二次嫁接法制备氨基修饰的硅基二氧化碳吸附剂

采用二次嫁接法制备了一系列氨基修饰的SBA-15二氧化碳(CO₂)吸附剂,利用XRD、BET、热重、元素分析、电镜、红外等表征手段对吸附剂进行了表征,并通过固定床测量穿透曲线的方法研究了其CO₂吸附性能,分别考察了不同制备途径和不同有机胺类型等因素对吸附剂结构以及其CO₂吸附性能的影响,同时,还通过多次吸脱附实验考察了吸附剂循环吸脱附的稳定性。结果表明,超声法所制备的聚乙烯亚胺(PEI)嫁接的吸附剂具有最优的CO₂吸附性能,在CO₂分压为10 kPa,反应温度为25 ℃时,吸附量达到1.72 mmol/g;进行多次循环吸脱附实验后,吸附量未见明显降低,表明吸附剂具有稳定的循环吸附性能。     

离子液体捕集CO2

CO₂是导致温室效应的最主要成分,因此碳捕集技术的研究受到学术界和产业界的高度重视。离子液体具有不挥发、不燃烧、热稳定性好、溶解能力强、结构和性质可调节并可循环使用等特性,在CO₂的吸收/分离领域展现了广阔的应用前景。本文系统地综述了近年来常规离子液体、功能化离子液体、支撑离子液体膜、聚合离子液体以及离子液体与分子溶剂的混合物在捕集CO₂方面的研究进展;讨论了离子液体的阳离子结构、阴离子类型、烷基链长度、阴/阳离子的氟化程度和功能化、离子液体的负载作用和聚合效应以及体系的温度和压力对CO₂选择性捕集性能的影响;分析了可能的捕集机理以及各种捕集方法的优点和缺点;提出了目前需要进一步研究的若干重要问题,并对其发展前景进行了展望。     

非胺类CO2吸收剂的研究进展

针对CO₂所带来的全球气候变化问题,本文综述了可用于捕集CO₂的非胺类吸收剂类型,认为氨基酸盐、氨基酸-碳酸钾体系、离子液体、生物型吸收剂、钙基吸收剂分别具有较高的CO₂循环吸收负荷、低毒性、热稳定性好、较优的生物相容性、钙源易获取的优势,可以弥补胺类吸收剂在吸收-解吸CO₂时腐蚀性强、再生能耗高、对环境产生二次污染等方面的不足。氨基酸盐、氨基酸-碳酸钾体系可应用于具有一定规模的CO₂捕集工业中;离子液体可应用于精准、绿色环保去除CO₂工业中;生物型吸收剂可用于规模小、CO₂浓度低的工业中;钙基吸收剂可运用于CO₂浓度高的工业中。上述吸收剂皆具有一定的工业前景。     

氨水捕集模拟烟气中二氧化碳的实验与理论研究

介绍了氨水捕集CO₂的反应原理, 利用鼓泡反应器开展了氨水碳捕集实验研究. 研究了氨水浓度、CO₂浓度、温度等因素对脱除效率的影响. 研究发现, 提高氨水质量分数和pH值均可增大CO₂脱除效率|增大CO₂浓度和入口气体流量后脱除效率呈现下降趋势|最佳脱除温度为45 ℃. 红外光谱分析表明, 氨水吸收后的主要成分是碳酸氢铵. 研究结果对进一步开展氨法捕集CO₂研究有较大的参考价值.     

离子交换树脂固态胺复合材料的制备、表征及CO2吸附

以离子交换树脂（D001）为载体,四乙烯五胺（TEPA）为改性剂,采用三种不同的方法制备了一系列固态胺吸附剂。采用N₂吸附-脱附、傅里叶变换红外光谱（FT-IR）、热重分析（TGA）等手段对吸附剂进行表征。在固定床反应器中考察了TEPA负载量、吸附温度、进气流量和CO₂分压等因素对CO₂吸附性能的影响。结果表明,配位法制得的固态胺吸附剂分散性和稳定性较好,且在TEPA负载量为40%,吸附温度为65℃,进气流量为40 mL/min时有最大CO₂吸附量达4 mmol/g。经过10次吸附-脱附循环实验后,CO₂吸附量下降3.98%。热力学、动力学研究结果表明,CO₂吸附是物理吸附和化学吸附的结果。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.