CaO高温吸附捕集CO2-制备CaO的钙基前驱体材料筛选

价格低廉的CaO材料在高温下能高效吸附捕集CO2气体,被认为是碳减排的有效方法之一．然而,CaO长时间循环碳酸化／煅烧解吸后,其CO2的化学吸附容量下降,稳定性较差,限制了该材料的工业应用．本文采用天然钙源（牡蛎壳和方解石等）和化学试剂（醋酸钙）为钙基前驱材料制备CaO．采用扫描电子显微镜（SEM）,X射线衍射仪（XRD）和氮气吸附仪等手段对制备的CaO材料进行形貌和物理结构的分析表征;在高温和模拟的烟道气氛条件下（10％C02和90％N2）,采用热重分析仪测量CaO吸附CO2的能力和长时间循环碳酸化／煅烧解吸后的稳定性．我们经过与目前所报道的其他钙基吸附材料进行比较,并结合钙基前驱材料的市场价格,发现CaO（醋酸钙）的CO2吸附能力和稳定性较为理想,醋酸钙在高温烟气捕碳方面具有非常好的应用前景．     

Simple fabrication of a phosphorus-doped hierarchical porous carbon via soft-template method for efficient CO2capture

Hierarchical porous carbons are widely used as adsorbents, catalyst supports, electrode materials, and other applications because of their high specific surface area (SSA), varied pore structure, adjustable porosity, and excellent physicochemical stability. Introducing heteroatoms such as N, P, or S, with electronegativities different from that of carbon, into the carbon skeleton can change the chemical properties of the surface and the density of the electron cloud around the carbon matrix, thus altering interactions of CO₂molecules with the surface and improving CO₂adsorption capacity. Therefore, doping heteroatoms in carbon materials has attracted a great amount of attention. In this paper, the template method was used with F108 (polyethylene glycol–polypropylene glycolpolyethylene glycol) as the template, resorcinol and formaldehyde solutions as the carbon sources, phosphoric acid as the phosphorus source, and KOH as the activator to prepare phosphorus-doped hierarchical porous carbons. Through a series of characterization and CO₂adsorption experiments, the influence of the amount of KOH and template agent on the pore structure of carbon materials was studied. We conclude that these phosphorus-doped hierarchical porous carbon materials are promising CO₂adsorbents.     

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)。     

Preparation of biomass-derived phosphorus-doped microporous carbon material and its application in dye adsorption and CO2 capture

Microporous P-doped carbon materials are synthesized by a pyrolysis method using MCM-22 as a template, sucrose as a precursor, and phosphoric acid as phosphorus sources. The results show that the pore structure of the carbon materials can be adjusted by changing the amount of phosphoric acid and template. When the P/C molar ratio is 0.075, the obtained P-doped microporous carbon material shows excellent specific surface area up to 621 m²/g and shows a high adsorption capacity of 199.40 mg/g for crystal violet dye, with a removal rate of 98.9%. When testing the CO₂ adsorption capacity, it was found that the maximum adsorption capacity reached 63 mg/g and remained stable after 10 adsorption and desorption cycles, with excellent cycle stability. The adsorption obeys pseudo-second-order kinetic model, and the adsorption isotherm follows the Langmuir model.     

多孔材料的二氧化碳吸附与光催化转化研究进展(英文)

太阳能光催化是CO_2转化和利用的新兴技术,直接利用洁净充足的太阳能将自然界富有的"温室气体"CO_2转化成化学燃料,不仅有利于消除大气温室效应,而且能缓解能源短缺问题,因而成为人们研究的一个重要方向.但目前CO_2的吸附和转换效率还很低,这是太阳能光催化CO_2资源化的最大障碍.高性能光催化剂的设计和合成是这项技术的关键.针对CO_2光还原反应的特异性,理想的光催化材料应该具有以下功能:强的CO_2吸附能力和高的光催化活性.将光催化剂与对CO_2具有高吸附性的多孔材料结合,就可以将CO_2吸附并富集在吸附剂周围的光催化剂表面上以进行催化转化,因此基于高效多孔吸附材料构筑光催化体系成为光催化转化CO_2的重要研究方向之一.CO_2的循环利用包括吸附和转化两方面,高吸附量的多孔材料是获得CO_2高转化效率的前提.本文首先以多孔材料结构参数及性能指标为主线,对无机多孔材料、金属有机框架材料及微孔有机聚合物材料的研究进展及应用前景进行了评述.通过对多孔材料的改性和新型多孔材料的开发,CO_2的吸附能力得到一定的提升,但是仅仅依靠多孔材料的吸附分离,不能实现CO_2中的碳资源循环.在此基础上,本文重点评述了多孔光催化材料在CO_2光催化转化中的最新研究进展.采用多孔材料与光催化剂结合,可增加材料的比表面积,在界面处暴露更多的活性位点,有利于光催化CO_2转化的进行;同时,通过孔结构和基团调控,可以调控光催化剂的反应活性和产物选择性.特别是金属有机框架材料与微孔有机聚合物材料,改变构建单元的官能团和制备技术还可以实现光谱响应范围的调控,提高太阳光的利用率.大量文献对比发现,引入较高CO_2吸附效率的多孔材料构建光催化体系,CO_2光催化转化的效率及产物选择性显著提高.最后,本文对多孔材料在CO_2光催化转化领域的研究现状与亟待解决的问题进行了剖析,提出了下一步可能的研究方向:(1)提高多孔材料自身的稳定性如耐水性能与光/热稳定性;(2)发展光催化材料在多孔载体的微观组装方法,不影响CO_2吸附效率的前提下提高光催化活性;(3)深入研究多孔光催化材料内部与表面的CO_2转化机理,为进一步提高吸附与转化效率提供理论指导.     

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。     

CO2 capture through halogen bonding: A theoretical perspective

Halogen bonding interactions between several halogenated ion pairs and CO2 molecules have been investigated by means of density functional theory calculations. To account for the influence of solvent environment, the implicit polarized continuum model was also employed. The bromide and iodide cations of ionic liquids (ILs) under study can interact with CO2 molecules via X O interactions, which become much stronger in strength than those in the complexes of iodo-perfluorobenzenes, very effective halogen bond donors, with CO2 molecules. Such interactions, albeit somewhat weaker in strength, are also observed between halogenated ion pairs and CO2 molecules. Thus, the solubility of CO2 may be improved when using halogenated ILs, as a result of the formation of X O halogen bonds. Under solvent effects, the strength of the interactions tends to be weakened to some degree, with a concomitant elongation of intermolecular distances. The results presented here would be very useful in the design and synthesis of novel and potent ILs for CO2 physical absorption.     

P-doped g-C3N4 as an efficient photocatalyst for CO2 conversion into value-added materials: a joint experimental and theoretical study

The photocatalytic yield of g-C₃N₄ for CO₂ reduction was modified by phosphorus doping. Possible reaction pathways for CO₂ reduction on the P-doped g-C₃N₄ (PCN) surface were investigated by density function theory calculations for the first time. The experimental results showed that P doping increases the carriers' lifetime, which improves the production of CH₄ through the increase in the driving force of the electrons. The partial density of states of the PCN showed that the valence band maximum and conduction band minimum are composed of p_x, p_y, and, s orbitals of the N atoms and p_z states of carbon, nitrogen, and phosphorus, respectively. Mechanism studies confirm that formic acid, formaldehyde, methanol, and methane are the most probable products. Methane, having positive adsorption energy, can be easily desorbed from the PCN surface, and the Gibbs activation energy of the final step is 1.98 eV. The formation of H₂COOH is the rate-determining step.     

膜吸收-再生循环技术捕集CO_2操作性能及其参数优化研究

采用N-甲基二乙醇胺(MDEA)+哌嗪(PZ)复合溶液作为捕集CO2吸收剂,研究了膜吸收-再生循环装置的操作性能,考察了气液流量、吸收剂浓度和再生电压等因素对捕集率和传质通量的影响,采用正交实验方法,优化操作条件,确定最佳操作方案。结果表明,气体流量对捕集率的影响明显大于液体流量的影响;气体流量增大对传质通量影响不明显;吸收剂浓度的增大使传质通量迅速增大,但大于一定值时通量不再增大;正交实验得出最佳操作条件为液体流量110 mL/min、气体流量0.65 L/min、吸收剂总浓度2.5 mol/L和再生电压210 V,捕集率大于95%,传质通量维持在5.86×10-4mol/(m2.s)。     

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.     

Aktivierung von CO2 an Übergangsmetallzentren: Zum Ablauf der CO2-Reduktion an Nickel(0)-Fragmenten

Activation of CO₂ at Transition Metal Centres: The Route of the CO₂ Reduction at Nikel(0) Moieties A competing reaction in the catalytic cyclooligomerization of hex-3-yne and CO₂ at the (TMED)Ni(0)-fragment (TMED = N,N,N′,N′-tetramethylethylendiamine) is the formation of carbon monoxide and (TMED)Ni(CO₃). So it is possible to explain the generation of II (TMED)Ni(diethylmalicacidanhydride) and III (a nickel trimer with two (TMED)Ni(CO₃) units). Both complexes are characterized by X-ray analysis. The reduction of CO₂ to CO most likely proceeds via an intermediate in which two molecules of carbon dioxide are coupled head-to-tail to form a metallacycle. An ab initio scf geometry optimization supports the existence of such an intermediate.     

A protophilic solvent‐assisted solvothermal approach to Cu‐BTC for enhanced CO2 capture

Cu‐BTC–ethylenediamine (EDA)/polyethyleneimine (PEI) adsorbents were synthesized using a protophilic solvent‐assisted solvothermal method. EDA was introduced to enhance the degree of activation due to its lower boiling point allowing it to be removed easily compared with dimethylformamide. A contrast experiment was done by introducing PEI to the solvothermal solution considering its higher boiling point. Powder X‐ray diffraction, scanning electron microscopy and Raman spectroscopic characterizations were performed to investigate the effect of EDA/PEI on crystallinity and morphology of the adsorbents. ¹H NMR characterization and elemental analysis were performed to study the removal rate of organic guest molecules and the degree of activation. Nitrogen physical adsorption and CO₂ adsorption isotherms were used to measure the surface area and CO₂ adsorption capacities. The CO₂ adsorption mechanism of the synthesized adsorbents is mainly dependent on physisorption determined by surface area. Furthermore, open metal sites generated by the enhancement of degree of activation also promote the CO₂ adsorption performance. Therefore, adsorbents synthesized using the protophilic solvent‐assisted solvothermal method exhibit excellent CO₂ adsorption performance. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental nibble for computational chemists: On the construction and CO2 capture by different zeolite imidazole ester framework-8 and ionic

The combination of zeolitic imidazolate framework-8 (ZIF-8) and ionic liquids (ILs) to create porous ionic liquids (PILs) is highly significant for efficient carbon dioxide (CO₂) capture and the advancement of carbon capture, utilization, and storage (CCUS) technologies. To further investigate the CO₂ capture characteristics of different PILs, two different-sized ZIF-8 structures and two functionalized ILs were prepared. Additionally, the enhancement factor of the reaction process was calculated using the dual-film theory and mass transfer coefficient. The results demonstrated that the original [PMIm]Cl had low CO₂ absorption capacity at ambient temperature and pressure, whereas the functionalized ILs had a maximum CO₂ capture capacity of approximately .31 mol/mol, with the 20 wt% concentration of tetraethylene pentamine-2-methylimidazole ([TEP][MIm]) exhibiting the highest CO₂ capture capacity of around 1.93 mol/mol. The synthesized PILs demonstrated a maximum CO₂ capture capacity of approximately 2.22 and 2.16 mol/mol at 20 and 10 wt% ionic concentrations, respectively, with a porous ionic liquid addition of 1.0/100 g. The corresponding enhancement factors were 1.53 and 1.59, respectively. These findings have significant implications for CCUS technology.     

高效SnO2纳米片催化剂用于CO氧化

SnO2是一种具有丰富表面缺位氧的n型半导体,其晶格氧亦可还原.另外其熔点高达1630oC,具有较高的热稳定性能.在过去的几十年中, SnO2主要用作气敏材料.而其作为催化材料的性能,特别是用于大气污染治理则鲜见报道.在过去的几年中,本课题组系统研究了SnO2的催化化学,发现利用传统共沉淀法制备的SnO2纳米粉末,在焙烧温度高于500 oC时,其比表面积通常低于20 m2/g,因而限制了其氧化活性.在SnO2晶格中掺杂Fe、Cr、Mn、Ce和Ta等形成固溶体可有效提高其比表面积并产生更多的活性氧物种,因而其对CO和CH4的氧化活性及稳定性大幅度提高.本课题组近期研究结果表明,采用熔盐法制备的高纯SnO2纳米棒单晶比SnO2纳米颗粒和纳米微球等具有更优异的CO氧化活性,260 oC即可完全氧化CO.且在240–260 oC狭窄温度区间发生转化率突跃,表现出类似贵金属的催化行为.值得指出的是, SnO2纳米棒的比表面积(1 m2/g)远低于其他几种形貌的材料,且无活泼氧存在.但研究表明SnO2纳米棒具有优先暴露的(110)活泼晶面,是导致其活性优良的主要原因.另外,我们采用简单共沉淀法成功制备了高比表面介孔Cu-Sn复合氧化物纳米片(196 m2/g),其在140 oC即可将CO完全氧化,且具有优良的抗水失活性能.因此, SnO2的形貌是影响其催化活性的主要因素之一,但迄今未见较系统深入的研究.在上述工作基础上,本文通过水热法,不添加任何有机模板剂,成功制备了厚度约10 nm的介孔SnO2纳米片和纳米棒及纳米颗粒混合物样品;采用常规共沉淀法制备了SnO2纳米颗粒.并将以上三种不同形貌的SnO2纳米材料用于CO氧化.利用SEM、XRD、N2吸附-脱附、H2-TPR和XPS探讨了不同形貌SnO2催化剂的体相结构和表面性质及其对催化性能的影响.与SnO2纳米颗粒相比,介孔SnO2纳米片具有高的比表面积、孔体积及更活泼的氧中心,因此后者CO氧化活性远高于前者.在空速18000 mL/(g·h)时, SnO2纳米片在260 oC即可完全氧化CO.而SnO2纳米颗粒的CO完全氧化温度高于360 oC. SnO2纳米棒和纳米颗粒的混合样品虽然其比表面积和孔体积及表面活性氧的活性仅略高于SnO2纳米颗粒,但XRD定量结果表明,其具有更多的暴露(110)活泼晶面,因而活性也高于SnO2纳米颗粒. SnO2纳米片催化剂的寿命及抗水性能测试结果表明,该催化剂具有良好的稳定性,且水蒸气仅对其活性产生可恢复的影响.进一步优化其性能, SnO2纳米片有可能用于实际汽车尾气状况下的CO催化清除.     

Structure and properties of polymer modified TiO2 pillared montmorillonite

With the aim of improving the microstructures and properties of TiO₂ pillared montmorillonite (MMT), a long-chain polymer (polyoxypropylenediamine, PPO-D 2000) was used as a template to synthesize composite pillared MMT. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer, Fourier Raman (FT-Raman) spectrophotometer, thermo-gravimeter/differential thermogravimeter (TG/DSC), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) methods. The results show that as compared to low-molecular weight surfactant, this polymer significantly expanded the interlayer spacing and thus more TiO₂ could be intercalated into MMT. The specific surface area of polymer/TiO₂ pillared MMT was increased by 13% with comparison to TiO₂ pillared MMT and rose to 241.52 m²/g. Both the pore diameter and volume are doubled, and thus the pore structure is optimized markedly. The investigation on the photo-catalytic degradation of methyl orange in aqueous solution show that the modulation of polymer molecules raise the adsorption content of montmorillonite and improve the photo-catalytic activity. Therefore, this process provides a novel alternative to design and prepare the advanced eco-catalytic materials with high adsorption capacity and photo-catalytic activity. __________ Translated from Huaxue Tongbao, 2007, 12: 936–941 [译自: 化学通报]     

CO2-activation and enhanced capture by C6Li6: A density functional approach

In this study, we propose a simple and yet effective approach for capture and storage of CO₂ by C₆Li₆. C₆Li₆ possesses a planar star-like structure, whose ionization energy is lower than that of Li atom and hence, it behaves as a superalkali. We have systematically studied the interaction of successive CO₂ molecules with C₆Li₆ using long-range dispersion corrected density functional ωB97xD/6-311 + G(d) calculations. We notice that these interactions lead to stable C₆Li₆-nCO₂ complexes (n = 1-6) in which the structure of CO₂ moieties is bent appreciably (122-125°) due to electron transfer from C₆Li₆, whose planarity is distorted only slightly (≤7°). This clearly suggests that the CO₂ molecules can successfully be activated and captured by C₆Li₆. It has been also noticed that the bond-length of CO₂ in C₆Li₆-nCO₂ complexes increases monotonically whereas adsorption energy decreases, ranging 3.18-2.79 eV per CO₂ with the increase in n. These findings establish the potential of C₆Li₆ for capture and storage of CO₂ molecules.     

Postsynthetic amine modification of porous organic polymers for CO2 capture and separation

Porous organic polymers (POPs) constitute an important class of sorbents studied in various adsorption and separation processes. Their unique properties, including high surface areas, adjustable pore sizes, and surface chemistries make them ideal candidates for CO₂ capture. To achieve a high CO₂ adsorption capacity and selectivity, particularly at the low partition pressures required for post-combustion CO₂ capture or direct capture of CO₂ from the atmosphere, incorporating amines onto the polymer frameworks or within the pores has shown much promise. This review provides a comprehensive summary of recent studies on the synthesis and CO₂ capture performance of amine-functionalized POPs. The review also provides a detailed discussion of structure-performance relationships, focusing on how the loading amount and amine type influence CO₂ capture capacity, CO₂/N₂ selectivity, heat of adsorption, sorption kinetics, and recyclability of POPs. Additionally, the authors offer their perspective on the challenges associated with the practical implementation of amine-modified POPs for CO₂ capture.     

调控强活性位点的智能光响应CO2吸附剂

光响应CO₂吸附剂能够通过外部光照的方式有效调节其捕获CO₂的能力,在吸附过程中具有可控性好和能源利用效率高的优势.然而目前报道的光响应CO₂吸附剂主要用于对弱吸附位点的调控,对强吸附位点的调控仍然是一项具有挑战性的任务.本工作构筑了一种光响应智能吸附剂,实现了对CO₂强吸附位点的光响应调控.吸附剂的构筑通过将具有顺反异构体的偶氮苯衍生物和含有伯胺的硅烷偶联剂引入介孔氧化硅实现.光照前偶氮苯处于反式构型,导致伯胺的静电势降低,充分暴露活性位;光照后偶氮苯转变为顺式构型,导致伯胺静电势的增加以及活性位点的遮蔽.吸附量在两种状态下的变化率能够达到43%,并且这一调节过程是可逆的.偶氮苯在不同构型下对伯胺的静电势产生了差异化的影响,从而实现了对吸附能力的调控.     

Unravelling the Promotional Effect of La2O3 in Pt/La-TiO2 Catalysts for CO2 Hydrogenation

This work reports the preparation of a La₂O₃-modified Pt/TiO₂ (Pt/La-TiO₂) hybrid through an excess-solution impregnation method and its application for CO₂ hydrogenation catalysis. The Pt/La-TiO₂ catalyst is characterized by XRD, H₂ temperature-programmed reduction (TPR), TEM, X-ray photoelectron spectroscopy (XPS), Raman, EPR, and N₂ sorption measurements. The Pt/La-TiO₂ composite starts to catalyze the CO₂ conversion reaction at 220 °C, which is 30 °C lower than the Pt/TiO₂ catalyst. The generation of CH₄ and CO of Pt/La-TiO₂ is 1.6 and 1.4 times greater than that of Pt/TiO₂. The CO₂ temperature-programmed desorption (TPD) analysis confirms the strengthened CO₂ adsorption on Pt/La-TiO₂. Moreover, the in situ FTIR experiments demonstrate that the enhanced CO₂ adsorption of Pt/La-TiO₂ facilitates the formation of the active Pt–CO intermediate and subsequently boosts the evolution of CH₄ and CO. The cycling tests reveal that Pt/La-TiO₂ shows reinforced stability for the CO₂ hydrogenation reaction because the La species can prevent Pt nanoparticles (NPs) from sintering. This work may provide some guidance on the development new rare-metal-modified hybrid catalysts for CO₂ fixation.