傅立叶变换红外光谱技术在超临界CO2作用聚合物体系中的应用

超临界CO₂（scCO₂）作为一种物理化学性质优良、具有高扩散速率及优良溶解性能的溶剂,在科学研究及工业生产中广受青睐。将scCO₂应用于聚合物体系中,CO₂ 与聚合物间特殊的相互作用有利于CO₂分子在聚合物中的吸附与扩散。同时通过CO₂的吸附及其对聚合物的溶胀和塑化作用,聚合物所处微观化学环境以及整体结构性质会发生一定的变化。由于傅立叶变换红外光谱（FTIR）技术能够有效地考察化学环境变化对分子结构造成的影响,这一表征技术在超临界CO₂作用体系中广为应用。本文主要选取了近年来利用FTIR技术考察scCO₂作用于聚合物体系的一些实例,从CO₂-聚合物相互作用机理,scCO₂对聚合物或生物大分子的加工过程的影响两方面,阐述了利用红外光谱技术在scCO₂作用体系中的应用以及前景。     

超临界CO_2下的聚合物结晶形态和动力学研究现状北大核心CSCD

聚合物结晶一直以来是高分子凝聚态研究的热点,随着超临界流体尤其是超临界CO2(scCO2)在聚合物方面应用日益增加,对超临界条件下的聚合物结晶研究显得更加重要。scCO2在聚合物中溶解度较高,增塑效果好,能显著降低玻璃化温度(Tg)和熔点(Tm),改变聚合物的晶体形态,并对动力学过程产生较大影响。因此,聚合物在scCO2条件下结晶行为的深入研究,在实际应用中起着重要的指导作用。本文对scCO2作用下的链型、晶体形态、共混物特点和结晶动力学过程的研究现状进行综述。     

CO2/H2在不同形态ZrO2上的吸附行为

利用傅立叶变换红外光谱技术(FT-IR)考察了CO2和CO2＋H2在不同形态氧化锆上的吸附和转化行为，结果表明,氧化锆的形态影响CO2的吸附形式和表面物种的生成.无定型氧化锆上主要生成碳酸氢盐和离子碳酸盐，单斜氧化锆上还出现了双齿碳酸盐，而在四方氧化锆上出现最强的线式吸附CO2，并生成聚碳酸盐.在氢气存在的条件下，单斜氧化锆上生成甲烷而在四方氧化锆上则生成甲酸盐.     

表面活性剂修饰对MCM-41负载离子液体吸附CO2影响的研究

以表面活性剂修饰的MCM-41为载体,采用浸渍法制备了负载离子液体[NH2p-mim][PF6]的二氧化碳吸附剂,考察了表面活性剂对离子液体在MCM-41上分散的影响以及所导致的CO2吸附性能的变化.利用红外光谱(FT-IR),X-射线衍射(XRD),高分辨透射电子显微镜(HRTEM),热重分析(TG)技术对所合成的负载型离子液体吸附剂进行了表征研究,并与其吸附CO2的性能变化、离子液体与表面活性剂相互作用方式等因素进行了关联.结果表明:MCM-41负载离子液体后对CO2的吸附性能略有提高,而经表面活性剂修饰的MCM-41负载离子液体后,对CO2的吸附容量较载体本身提高了2.5倍.这一方面是因为表面活性剂胶束改善了MCM-41上离子液体的分散性,另一方面是表面活性剂胶束对离子液体分子上电荷分布的影响,导致离子液体内部阴阳离子之间的相互作用减弱,从而引起离子液体中-NH2上N原子电子云密度增大,使其与CO2作用更容易.CO2在经表面活性剂修饰后的MCM-41负载离子液体[NH2p-mim][PF6]吸附剂上的吸附受扩散控制,其吸附-脱附CO2所需能量较小,经过5次吸附-脱附循环后,其吸附性能仍保持稳定.热重分析结果表明,经表面活性剂修饰后的MCM-41负载离子液体吸附剂在100℃下氮气气氛再生时不会发生性质改变.     

超临界CO_2溶胀聚合物的研究及其应用

本文介绍超临界CO2 溶胀聚合物的研究及其应用 ,包括聚合物与超临界CO2 相互作用 ,溶胀行为的理论模型以及溶胀后的聚合物的用途 ,如制备微孔聚合物材料、渗透小分子和超临界溶胀聚合等     

单分散SiO2的焙烧温度对Rh基催化剂上CO加氢反应性能的影响

在比较了分别以商业SiO2和采用Sto?ber法制备的单分散SiO2为载体的Rh-Mn-Li/SiO2催化剂催化CO加氢反应性能的基础上,进一步调变了Stober法制备SiO2时的焙烧温度,并考察了其对Rh-Mn-Li/SiO2催化CO加氢性能的影响.利用N2吸附-脱附、傅里叶变换红外(FTIR)光谱、H2程序升温还原(H2-TPR)、程序升温表面反应(TPSR)等方法对载体及催化剂的物理化学性能进行了表征.结果表明:不同温度焙烧的载体表面具有不同的Si―OH数量,从而影响金属的分散状态及Rh和Mn之间的相互作用.载体表面较多的羟基有利于Rh的分散和CO的吸附,从而增强催化剂的反应活性.载体表面适当数量的羟基能够得到适中的Rh与Mn之间的相互作用,使催化剂具有合适的CO解离能力,有利于CHx的CO插入反应,从而提高了C2含氧化合物的选择性.     

Bi系超导体原始粉末的化学吸附行为

用傅氏变换红外光谱（FTIR）研究了不同方法制备的Bi系超导体原始粉末研磨过程中；自环境气相中的化学吸附行为．结果表明；在空气中研磨，粉末化学吸附空气中的CO2和H2O在氩气中研磨则无化学吸附现象．用Bi系超导体晶体结构的特征分析了吸附机理.     

丙酸水相加氢反应中Ru负载量对C-C键断裂的影响

考察了（1.0、4.0、6.0 wt.%）Ru/ZrO2催化剂的丙酸水相加氢性能。采用N2物理吸附、CO脉冲化学吸附、H2程序升温还原（H2-TPR）、CO和丙酸吸附傅里叶变换红外光谱（FTIR）研究了Ru/ZrO2催化剂的物理化学性质。CO-FTIR表明,Ru负载量增加,催化剂表面Ru粒子的富电子程度增加,更接近金属Ru的本征特性。丙酸FTIR表明,丙酸分子在Ru/ZrO2催化剂表面经解离吸附主要形成丙酰基和丙酸盐物种。随Ru含量增加,丙酰基更容易发生脱羰反应,导致C-C键断裂。     

源自密胺基多孔聚合物的富氮微孔炭及选择性吸附CO_2

以间苯二甲醛和三聚氰胺为原料,通过Schiff碱缩合反应合成了密胺基多孔聚合物(POP),经高温炭化后得到富氮微孔炭(NMC).利用N2吸脱附和傅里叶变换红外(FTIR)光谱表征了POP和炭化后产物NMC的结构和组成,与POP相比,NMC的官能团数量减少,比表面积和微孔孔容大幅增加.元素分析表明NMC含氮量高达12.5%(w).采用体积法测定了CO2、CH4和N2在NMC上的单组分吸附平衡等温线,NMC展示出良好的CO2吸附性能,298 K、100 kPa下CO2平衡吸附量可达2.34 mmol·g-1.双位Langmuir(DSL)模型和单位Langmuir(SSL)模型分别较好地描述了CO2、CH4和N2在NMC上的吸附平衡数据,在此基础上,应用理想吸附溶液理论(IAST)预测了双组分混合气在NMC上的吸附等温线,结果表明NMC对CO2-N2和CO2-CH4有非常高的CO2吸附选择性,分别为144.9和12.8.     

超临界CO2中的表面活性剂

介绍了超临界CO2中表面活性剂的结构特征以及聚合物表面活性剂和小分子表面活性剂的研究进展。指出了开发亲CO2表面活性剂的一些基本原则,其中降低表面活性剂在H2O／CO2表面的界面张力和提高表面活性剂的吸附能力比溶解度更为重要。建议加强CO2表面活性剂的研究与开发。     

Poly(amide-6-b-ethylene oxide)/[Bmim][Tf_2N] blend membranes for carbon dioxide separation

Poly(amide-6-b-ethylene oxide)(Pebax1657)/1-butyl-3-methylimidazo-lium bis[trifluoromethyl)sulfonyl]-imide([Bmim][Tf_2N]) blend membranes with different [Bmim][Tf_2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO_2, N_2,CH_4 and H_2 were studied, and the physical properties were characterized by differential scanning calorimeter(DSC) and X-ray diffraction(XRD). Results showed that [Bmim][Tf_2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg(PE) and crystallinity(PA). With the addition of [Bmim][Tf_2N], the CO_2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf_2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO_2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf_2N], the increase of fractional free of volume(FFV) and plasticization effect. However, the CO_2 permeability reduced firstly when the [Bmim][Tf_2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf_2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf_2N]decreased the content of EO units available for CO_2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf_2N] blend membranes, the permeabilities of N_2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO_2 permeability increased with the increase of feed pressure for that the CO_2-induced plasticization effect was stronger than hydrostatic pressure effect.     

Resorcinol-formaldehyde resin-based porous carbon spheres with high CO_2 capture capacities

Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as CO_2 adsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high CO_2 capture capacity of 4.83 mmol/g and good CO_2/N_2 selectivity of ~17-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent CO_2 sorption performance at room temperature and ambient pressure.     

PLASMA POLYMERIZATION OF ACETYLENE/CO_2/H_2

A study has been made on the plasma polymerization of acetylene/CO_2/H_2 in a capacitively coupled RF plasma. The monomer mixture yielded a crosslinked film with light brown color. A kinetic study is reported for the plasma polymer ization of acetylene/CO_2/H_2. The effects of discharge power level and reactor geometry on the rate of polymer formation are reported. The structure of the plasma polymer is investigated by IR study.     

超临界CO_2技术在高分子科学中应用的研究进展

本文综述了超临界CO_2的特殊性质，如溶解能力和溶胀能力随压力急剧变化等，总结了它在高分子科学中的应用，包括以它为介质的溶液聚合、乳液聚合、分散聚合、沉淀聚合反应及RESS技术、分级技术等．     

Mn-CaO催化剂上甲烷-二氧化碳共活化制C_2烃研究II.催化剂表征及反应机理研究

在Mn-CaO催化剂开展了一系列的表征,包括XRD,XPS,CO2-TPD.结合催化剂评价、表征结果,对催化反应机理进行了推测,指出Mn组分与催化剂的活性相关联而Ca组分的主要作用是提供吸附型的CO2(a)*,反应过程中形成的Mn3+/Mn2+离子对在CO2和CH4的活化过程中扮演了重要角色.     

生物降解型脂肪族不饱和聚酯碳酸酯 1.合成和表征

用CO_2、环氧乙烷、顺丁烯二酸酐进行三元共聚得到一种新型的脂肪族不饱和聚酯碳酸酯(AUPEC),并用IR、~1H NMR、DSC等进行了表征,共聚物链中CO_2和MA单元随机分布,不饱和单元可在0-0.5摩尔分数之间调节,共聚过程不发生双键交联和构型转化。EO的转化率可高达到93％,使AUPEC链上的双键发生反应,产物仍可溶解且热性能得到改善。     

Enhancing Electrochemical Reduction of CO_2 to Formate by Regulating the Support Morphology

Electroreduction of CO₂ to formic acid has attracted extensive attention,because it is a promising strategy to re-utilize CO₂ and reduce greenhouse gas emissions that may favor the mitigation of energy and environment issues.Although great efforts have been made to tune the structure and composition of catalysts aiming to improve CO₂ conversion efficiency,seldom studies have been focused on the support regulation.In this work,ordered,porous TiO₂ nanotube arrays have been used as model support to study the impact of pore structure for CO₂ electrochemical reduction.It has been revealed that Pd supported on TiO₂ nanotube arrays substrate exhibits enhanced performance towards CO₂ reduction,showing a higher formate Faradaic efficiency of 20%over than Pd supported on TiO₂ film substrate.This study will shed new light on the design and synthesis of efficient catalysts by tuning the morphology of support for CO₂ conversion.     

Green Monomer of CO_2 and Alkyne-based Four-component Tandem Polymerization toward Regio-and Stereoregular Poly(aminoacrylate)s

Green monomers, such as carbon dioxide(CO_2), are closely related to our daily life and highly desirable to be transferred to functional polymers with diverse structures and versatile properties because they are abundant, cheap, nontoxic, renewable, and sustainable. However, the polymerizations based on these green monomers are to be further developed. In this work, a facile CO_2 and alkyne-based one-pot, two-step, fourcomponent tandem polymerization was successfully established. The polymerization of CO_2, diynes, alkyl dihalides, and primary/secondary amines can proceed under mild reaction conditions and regio-and stereoregular poly(aminoacrylate)s with good solubility and thermal stability were obtained in high yields(up to 95%). Notably, distinctly different stereoregularity of resultant poly(aminoacrylate)s was realized via using primary or secondary amines. Using the former would readily generate polymers with 100% Z-isomers, whereas the latter furnished products with over 95% E-isomers. Through different monomer combination, the polymers with tunable structures and properties were obtained.Moreover, the tetraphenylethene units containing poly(aminoacrylate)s, showing the unique aggregation-induced emission characteristics,could function as a fluorescent probe for sensitive explosive detection. Thus, this work not only develops a facile CO_2 and alkyne-based multicomponent tandem polymerization but also provides a valuable strategy to fine-tune the polymer structures and properties, which could be potentially applied in diverse areas.     

SalenAl(O~iPr)催化CO_2与氧化环己烯共聚及影响因素研究

以SalenAl(OiPr)为催化剂,分别加入各种路易斯碱作为共催化剂催化二氧化碳与氧化环己烯共聚,发现共聚催化效率与共催化剂的供电子能力有关.分别研究催化剂浓度、共催化剂的用量、反应时间、反应温度、CO2压力等各种因素对该共聚反应的影响,发现SalenAl(OiPr)浓度为2 g/L时,以等摩尔量的二甲氨基吡啶(DMAP)作为共催化剂,在4 MPa的CO2和80℃下反应32 h,可得到碳酸酯键含量>99%的共聚产物,其催化效率高达495 g/g,13C-NMR检测表明共聚物为无规立构聚合物,GPC测得分子量Mn为55900,分子量分布比较窄(PDI=1.32).DSC得到共聚物的玻璃化转变温度为136℃,热重分析(TGA)可以看出共聚物在350℃可完全分解,具有优良的热分解性.     

Regulation of the activity,selectivity, and durability of Cu-based electrocatalysts for CO_2 reduction

CO_2 electroreduction offers a promising approach to alleviate global warming and reduce petroleum consumption simultaneously, due to its capability to convert the greenhouse gas CO_2 to valuable fuels and chemicals by using renewable electricity.Electrocatalyst has an essential impact on the CO_2 electroreduction performance. Among the diverse exploited materials, Cu is the only monometallic electrocatalyst that can produce CO and hydrocarbons. However, its activity, selectivity, and durability are not satisfactory for practical applications. Here, we make a comprehensive survey of the recent progress in enhancing Cu-based electrocatalysts with the strategies such as oxidation pre-treatment, heteroatom doping, morphological control, and surface modification. This review provides an overview of the current status and future opportunities for Cu-catalyzed CO_2 electroreduction. It may contribute to the rational design of Cu-based electrocatalysts with improved performance and thus advance practical CO_2 electrolyzer development.