介孔材料在卷烟工业中的应用进展

介孔材料具有比表面积高、结构可调、水热稳定性好和独特的吸附性能,在烟草行业具有较好的应用前景。总结了介孔材料的分类、合成以及在卷烟中选择性吸附特定物质的应用及相应的吸附机理,展望了介孔材料目前在卷烟中应用的研究方向。     

MgO/Al_2O_3/MCM-41对CO_2吸/脱附性能的研究

利用一步法制备了MgO/Al2O3/MCM-41吸附剂,采用XRD、氮吸附和CO2-TPD等手段表征了材料的结构特征和表面性质。研究发现,负载前后样品都具有有序的介孔孔道结构,介孔材料的孔道仍高度有序,对CO2的吸附能力较纯MCM-41有明显的改善。当负载量为20%时,对CO2的吸附量最大。吸附量经过3次循环测试,未见明显下降。     

TEPA-AM修饰的介孔材料吸附CO2性能的研究

将丙烯酰胺(AM)改性的四乙烯五胺(TE-PA)负载到介孔材料孔道内,形成氨基改性的CO2吸附材料。利用X射线衍射(XRD)、氮气物理吸附-脱附(BET)、红外等方法对样品进行了表征。通过动态吸附法研究了材料的CO2吸附和脱附性能,并与TEPA负载的吸附材料进行了比较。研究结果表明,在制备介孔分子筛MCM-41的过程中得到的一种结构规整度低的材料对TEPA-AM具有较好的分散性能,经过TE-PA-AM修饰的该材料表现出良好的CO2吸附性能,当TEPA-AM负载量达60%,该材料的吸附能力达到159.1mg/g;经过12次循环使用吸附量不下降。     

磷酸锆/介孔密胺树脂复合吸附材料的制备及性能研究

将介孔密胺树脂与无定形磷酸锆复合制得一种广谱性复合吸附材料,考察了复合吸附材料对SO2和NH3的吸附性能,采用X射线衍射仪、X射线光电子能谱仪、傅里叶变换红外光谱仪、热重分析仪和扫描电子显微镜等对复合吸附材料的结构、形貌、热稳定性进行表征.结果 表明:介孔密胺树脂呈网状多孔交联形貌,比表面积为548.81m2/g、孔径...     

功能化介孔氧化铝材料的制备及应用进展

介孔氧化铝因其在催化、吸附等领域具有巨大的应用前景,而受到国内外研究学者的广泛关注。随着工业化生产要求的不断提高,普通介孔氧化铝的使用逐渐受到限制,制备高性能的功能化介孔氧化铝材料将具有重大意义。功能化介孔氧化铝材料具有较高的催化活性、较强的机械和水热稳定性,不仅在催化、吸附领域受到极大重视,而且延伸到光学、医学等重要领域。综述了功能化介孔氧化铝材料的主要制备方法,包括原位合成法和浸渍法,并对两种方法存在的优缺点进行了比较。同时详细介绍了功能化介孔氧化铝材料的种类以及在催化、吸附分离和其它领域的应用,并展望了功能化介孔氧化铝材料的发展及应用前景。     

金属掺杂介孔氧化锆的合成与表征

采用直接合成法在非水溶剂中成功合成了分别由锌、镁等元素掺杂改性的介孔氧化锆分子筛,并用XRD、N2吸附-脱附、NH3-TPD等方法对其进行表征,还考察了影响合成的一些因素。结果表明,金属元素能够均匀地掺杂于介孔氧化锆的晶体骨架中。金属的掺入增加了介孔材料的热稳定性,但其骨架有所收缩,降低了有序度;络合剂三乙醇胺的加入增加了材料的热稳定性;模板剂P123的使用增加了介孔分子筛的有序度;金属的掺杂使得介孔分子筛制备的固体超强酸的酸位增多,酸度增强。     

纳米介孔CeO2的合成及表征

采用烷基聚氧乙烯基醚(Brij35)非离子型表面活性剂为模板剂,乙醇水溶液为溶剂合成了高比表面和孔径集中的介孔CeO2,考察了氨水和铈源的添加顺序、pH值等合成条件对介孔CeO2比表面、孔径分布和热稳定性的影响.运用XRD、FT-IR、DTA、N2吸附-脱附和比表面-孔径测定等手段进行了表征.结果表明,氨水加入铈源与模板剂的混合液中有利于形成介孔CeO2,且pH值在9～10范围内所得介孔CeO2材料具有较大的比表面积、孔容和较好的热稳定性.     

模板法制备TiO2介孔材料的研究进展

TiO2介孔材料在催化、吸附及分离等领域具有十分重要的应用,是当今介孔材料研究的热点之一。本文综述了介孔材料的分类,概述了模板法制备TiO2介孔材料的机理及不同类型的模板剂在TiO2介孔材料制备中的应用,指出了模板剂脱除过程中存在的问题,并对介孔材料的研究和应用前景进行了展望。     

两步晶化法制备介孔材料及其催化性能研究

采用两步晶化法,由MCM-22沸石前驱体合成了一种介孔材料.通过XRD、N2吸附-脱附、TEM、27A lMAS NMR以及吡啶吸附红外光谱等技术对样品进行了表征.结果显示所合成的样品不是微孔沸石与介孔材料的混合物,而是含强酸性中心、水热稳定性良好的新型介孔分子筛.利用异丙苯的裂解反应、苯和1-十二烯烃的烷基化反应,评价了其对大分子的酸催化活性,并与常规介孔材料MCM-41进行了比较.在350℃时,所合成的介孔材料和常规介孔材料MCM-41对异丙苯的裂解转化率分别为68.98%和48.80%.在210℃苯和1-十二烯烃的烷基化反应时,所合成的介孔材料和MCM-41对1-十二烯烃的转化率分别约为95.20%和86.89%,产物直链烷基苯的选择性分别约为88.11%和90.06%.结果表明所合成的介孔材料对大分子的酸催化性能优越于常规介孔材料MCM-41.     

消息报道

青岛能源所开发出介孔材料改性的聚酰胺复合膜由于比表面积大和孔结构可调等特点,介孔纳米材料在能量储存、气体分离、纳米催化等领域具有潜在的应用前景。中国科学院青岛生物能源与过程研究所研究员江河清带领的膜分离与催化研究组前期围绕界面相容性调控这一科学问题,以功能化介孔聚合物为基底,利用金属有机框架化合物(MOF)中的Al金属中心与介孔聚合物表面功能基团之间的配位作用,将纳米MOF限域在介孔聚合物孔道内,该类MOF表面的缺陷位点与CO2分子间存在较强的相互作用,显著地提高了MOF在低压条件下的CO2吸附容量。     

2D Transition Metal Carbides (MXenes) for Carbon Capture

Global warming caused by burning of fossil fuels is indisputably one of mankind's greatest challenges in the 21st century. To reduce the ever‐increasing CO₂ emissions released into the atmosphere, dry solid adsorbents with large surface‐to‐volume ratio such as carbonaceous materials, zeolites, and metal–organic frameworks have emerged as promising material candidates for capturing CO₂. However, challenges remain because of limited CO₂/N₂ selectivity and long‐term stability. The effective adsorption of CO₂ gas (≈12 mol kg^?1) on individual sheets of 2D transition metal carbides (referred to as MXenes) is reported here. It is shown that exposure to N₂ gas results in no adsorption, consistent with first‐principles calculations. The adsorption efficiency combined with the CO₂/N₂ selectivity, together with a chemical and thermal stability, identifies the archetype Ti₃C₂ MXene as a new material for carbon capture (CC) applications.     

Amine-impregnated MCM-41 in post-combustion CO2 capture: Synthesis,characterization, isotherm modelling

In this study, a composite mesoporous silica material MCM-41 (Mobil composite matter) is impregnated with monoethanolamine (MEA) as primary linear amine, benzylamine (BZA) as primary cyclic amine and N-(2-aminoethyl) ethanolamine (AEEA) as secondary diamine and the effects of amine loading, amine type, CO₂ partial pressure and adsorption temperatures on the CO₂ adsorption are investigated. The CO₂ adsorption performances of MCM-41 and amine impregnated MCM-41 samples are studied up to 1 bar of CO₂ partial pressure and the temperature range of 25–60 °C. The amine loadings (% impregnation) are optimized for maximum CO₂ uptake. The materials are characterised using N₂ adsorption/desorption isotherm, Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric (TGA) and Elemental (CHNS) analysis. The materials have shown good structural and thermal stability. The MCM-41-40%AEEA, MCM-41-40%BZA and MCM-41-50%MEA samples are exhibited the CO₂ adsorption capacity of 2.34 mmol/g (102.98 mg/g), 0.908 mmol/g (39.96 mg/g) and 1.47 mmol/g (64.69 mg/g) respectively. The CO₂ uptake of MCM-41-40%AEEA is 3.5 times higher than that of in MCM-41 (0.68 mmol/g) and it is also the highest reported value as di-amine impregnated MCM-41. The results indicated that the adsorption capacities of the materials (MCM-41 and MCM-41-40%AEEA) are decreased with an increase of adsorption temperature in the range of 25–60 °C. The Freundlich, Langmuir, Sips and Toth isotherm models are used to correlate and predict experimental CO₂ adsorption data. The Sips and Toth isotherm models are found to be better fitted with the experimental data. The isosteric heat of adsorption of MCM-41 and MCM-41-40%AEEA samples are also calculated from Van’t Hoff plot using iSorbHP-win instrumental analysis software in the experimental temperature range.     

Multi-Dimensional Molecular Self-Assembly Strategy for the Construction of Two-Dimensional Mesoporous Polydiaminopyridine and Carbon Materials

Two-dimensional (2D) mesoporous polymers, combining the advantages of organic polymers, porous materials, and 2D materials, have received great attention in adsorption, catalysis, and energy storage. However, the synthesis of 2D mesoporous polymers is not only challenged by the complex 2D structure construction, but also by the low yield and difficulty in controlling the dynamics of the assembly during the generation of mesopores. Herein, a facile multi-dimensional molecular self-assembly strategy is reported for the preparation of 2D mesoporous polydiaminopyridines (MPDAPs), which features tunable pore sizes (17–35 nm) and abundant N content up to 18.0 at%. Benefitting from the abundant N sites, 2D nanostructure, and uniform-large mesopores, the 2D MPDAPs exhibit excellent catalytic performance for the Knoevenagel condensation reaction. After calcination under N₂ atmosphere, the obtained 2D N-doped mesoporous carbon (NMCs) with large and uniform pore sizes, high surface areas, abundant N content (up to 23.1%), and a high ratio of basic N species (57.0% pyridinic N and 35.9% pyrrolic N) can show an excellent CO₂ uptake density (11.7 µmol m⁻² at 273 K), higher than previously reported porous materials.     

High pressure carbon dioxide adsorption on nanoporous carbons prepared by Zeolite Y templating

Nanoporous carbons were synthesized by chemical vapor deposition using furfuryl alcohol/butylene as a carbon source and zeolite Y as a hard template (ZYC). The ZYC were characterized by PXRD, N₂ sorption, and SEM. The carbon materials exhibited predominant microporosity, and the specific surface area increased from 2563 to 3010 m² g⁻¹ as the pyrolysis temperature was raised from 800 to 1000 °C. ZYC prepared at 1000 °C showed a CO₂ adsorption capacity of 986 mg g⁻¹_adsorbent at 40 bar 298 K, which surpasses the capacities of commercial carbons and mesoporous carbon CMK-3, and closely approaches the best performance of the metal organic framework MOF-177. The CO₂ adsorption capacities of the adsorbents were found to be closely correlated with the BET surface areas of the materials tested.     

Preparation and CO_2 adsorption properties of porous carbon by hydrothermal carbonization of tree leaves

Porous carbon materials were prepared by hydrothermal carbonization(HTC) and KOH activation of camphor leaves and camellia leaves. The morphology, pore structure, chemical properties and CO_2 capture ability of the porous carbon prepared from the two leaves were compared. The effect of HTC temperature on the structure and CO_2 adsorption properties was especially investigated. It was found that HTC temperature had a major effect on the structure of the product and the ability to capture CO_2. The porous carbon materials prepared from camellia leaves at the HTC temperature of 240℃ had the highest proportion of microporous structure, the largest specific surface area(up to 1823.77 m~2/g) and the maximum CO_2 adsorption capacity of 8.30 mmol/g at 25℃ under 0.4 MPa. For all prepared porous carbons, simulation results of isothermal adsorption model showed that Langmuir isotherm model described the adsorption equilibrium data better than Freundlich isotherm model. For porous carbons prepared from camphor leaves, pseudo-first order kinetic model was well fitted with the experimental data. However,for porous carbons prepared from camellia leaves, both pseudo-first and pseudo-second order kinetics model adsorption behaviors were present. The porous carbon materials prepared from tree leaves provided a feasible option for CO_2 capture with low cost, environmental friendship and high capture capability.     

氨基功能化多孔材料吸附二氧化碳研究进展

近年来,二氧化碳(CO_2)排放量日益增长,导致全球温室效应加剧,严重影响了人类的生存和发展。CO_2捕集、封存和利用技术被认为能在短期内大幅削减CO_2的排放量并能有效缓解温室效应而受到广泛关注。主要介绍了一些典型氨基功能化多孔材料吸附CO_2的最新研究进展,综述了多孔材料氨基功能化改性的原理以及优缺点,并围绕表面改性、结构调变和形貌控制等提高CO_2吸附性能的方法对每种材料体系进行了简要总结,最后对其存在的问题、发展前景进行了探讨和展望。     

Optimizing Sieving Effect for CO2 Capture from Humid Air Using an Adaptive Ultramicroporous Framework

Excessive CO₂ in the air can not only lead to serious climate problems but also cause serious damage to humans in confined spaces. Here, a novel metal–organic framework (FJI-H38) with adaptive ultramicropores and multiple active sites is prepared. It can sieve CO₂ from air with the very high adsorption capacity/selectivity but the lowest adsorption enthalpy among the reported physical adsorbents. Such excellent adsorption performances can be retained even at high humidity. Mechanistic studies show that the polar ultramicropore is very suitable for molecular sieving of CO₂ from N₂, and the distinguishable adsorption sites for H₂O and CO₂ enable them to be co-adsorbed. Notably, the adsorbed-CO₂-driven pore shrinkage can further promote CO₂ capture while the adsorbed-H₂O-induced phase transitions in turn inhibit H₂O adsorption. Moreover, FJI-H38 has excellent stability and recyclability and can be synthesized on a large scale, making it a practical trace CO₂ adsorbent. This will provide a new strategy for developing practical adsorbents for CO₂ capture from the air.     

Valuing Metal–Organic Frameworks for Postcombustion Carbon Capture: A Benchmark Study for Evaluating Physical Adsorbents

The development of practical solutions for the energy‐efficient capture of carbon dioxide is of prime importance and continues to attract intensive research interest. Conceivably, the implementation of adsorption‐based processes using different cycling modes, e.g., pressure‐swing adsorption or temperature‐swing adsorption, offers great prospects to address this challenge. Practically, the successful deployment of practical adsorption‐based technologies depends on the development of made‐to‐order adsorbents expressing mutually two compulsory requisites: i) high selectivity/affinity for CO₂ and ii) excellent chemical stability in the presence of impurities. This study presents a new comprehensive experimental protocol apposite for assessing the prospects of a given physical adsorbent for carbon capture under flue gas stream conditions. The protocol permits: i) the baseline performance of commercial adsorbents such as zeolite 13X, activated carbon versus liquid amine scrubbing to be ascertained, and ii) a standardized evaluation of the best reported metal–organic framework (MOF) materials for carbon dioxide capture from flue gas to be undertaken. This extensive study corroborates the exceptional CO₂ capture performance of the recently isolated second‐generation fluorinated MOF material, NbOFFIVE ‐1‐Ni, concomitant with an impressive chemical stability and a low energy for regeneration. Essentially, the NbOFFIVE ‐1‐Ni adsorbent presents the best compromise by satisfying all the required metrics for efficient CO₂ scrubbing.     

Carbon Dioxide Promotes Dehydrogenation in the Equimolar C2H2‐CO2 Reaction to Synthesize Carbon Nanotubes

The equimolar C₂H₂‐CO₂ reaction has shown promise for carbon nanotube (CNT) production at low temperatures and on diverse functional substrate materials; however, the electron‐pushing mechanism of this reaction is not well demonstrated. Here, the role of CO₂ is explored experimentally and theoretically. In particular, ¹³C labeling of CO₂ demonstrates that CO₂ is not an important C source in CNT growth by thermal catalytic chemical vapor deposition. Consistent with this experimental finding, the adsorption behaviors of C₂H₂ and CO₂ on a graphene‐like lattice via density functional theory calculations reveal that the binding energies of C₂H₂ are markedly higher than that of CO₂, suggesting the former is more likely to incorporate into CNT structure. Further, H‐abstraction by CO₂ from the active CNT growth edge would be favored, ultimately forming CO and H₂O. These results support that the commonly observed, promoting role of CO₂ in CNT growth is due to a CO₂‐assisted dehydrogenation mechanism.     

Advances in principal factors influencing carbon dioxide adsorption on zeolites

Abstract

We report the advances in the principal structural and experimental factors that might influence the carbon dioxide (CO₂) adsorption on natural and synthetic zeolites. The CO₂ adsorption is principally govern by the inclusion of exchangeable cations (countercations) within the cavities of zeolites, which induce basicity and an electric field, two key parameters for CO₂ adsorption. More specifically, these two parameters vary with diverse factors including the nature, distribution and number of exchangeable cations. The structure of framework also determines CO₂ adsorption on zeolites by influencing the basicity and electric field in their cavities. In fact, the basicity and electric field usually vary inversely with the Si/Al ratio. Furthermore, the CO₂ adsorption might be limited by the size of pores within zeolites and by the carbonates formation during the CO₂ chemisorption. The polarity of molecules adsorbed on zeolites represents a very important factor that influences their interaction with the electric field. The adsorbates that have the most great quadrupole moment such as the CO₂, might interact strongly with the electric field of zeolites and this favors their adsorption. The pressure, temperature and presence of water seem to be the most important experimental conditions that influence the adsorption of CO₂. The CO₂ adsorption increases with the gas phase pressure and decreases with the rise of temperature. The presence of water significantly decreases adsorption capacity of cationic zeolites by decreasing strength and heterogeneity of the electric field and by favoring the formation of bicarbonates. The optimization of the zeolites structural characteristics and the experimental conditions might enhance substantially their CO₂ adsorption capacity and thereby might give rise to the excellent adsorbents that may be used to capturing the industrial emissions of CO₂.