Genuine Pores in a Stable Zinc Phosphite for High H2 Adsorption and CO2 Capture

An uncommon example of stable mixed-ligand zinc phosphite with genuine pores has been synthesized by using zinc metal, inorganic phosphite acid, thio-functionalized O-donor (2,5-thiophenedicarboxylate, TPDC), and tetradentate N-donor [1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene, TIMB] units assembled into one crystalline structure according to a hydro(solvo)thermal method. This is a very rare case of a metal phosphite incorporating both N- and O-donor ligands. The tetradentate TIMB linker bound to zinc atoms of the isolated zincophosphite hexamers to form a 3D open-framework structure by crosslinking structural components of 1D chains and 2D layers. Here, the TPDC ligand acts as a monodentate binding model to functionalize its porous structure with the uncoordinated S atom and COO⁻ group. Interestingly, this compound demonstrates the highest H₂ storage capacity among organic–inorganic hybrid metal phosphates (and phosphites), and a good CO₂ capture at 298 K compared with the majority of crystalline materials. The possible adsorption sites and selectivity for CO₂ over H₂, N₂, and CO at 298 K were calculated by using density functional theory (DFT), the ideal adsorption solution theory (IAST), and fitting experimental pure-component adsorption data.     

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.     

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。     

Separation of H2O/CO2 Mixtures with Layered Adsorption Method for Greenhouse Gas Control

Multiple-layered vacuum swing adsorption technique was used and investigated in order to effectively keep the feed gas that flows into zeolite 13X zone being dry and keep the CAPEX down(not adding pre-treatment equipment). Activated carbon fiber(ACF) and alumina CDX were laid at the lower parts of the column as pre-layers to selectively adsorb moisture. Zeolite 13X was laid on the top of those two adsorbents as the main layer to capture CO₂. Systematic cyclic experiments show that water vapor was successfully contained within the ACF and CDX layers at cyclic steady states. It was also found that ultimate vacuum pressure played a decisive factor for stabilizing the water front, and achieving good CO₂ purity and recovery. The findings also reveal the pathway for large-scale CO₂ capture process.     

Construction of a Stable Crystalline Polyimide Porous Organic Framework for C2H2/C2H4 and CO2/N2 Separation

Utilization of porous materials for gas capture and separation is a hot research topic. Removal of acetylene (C₂H₂) from ethylene (C₂H₄) is important in the oil refining and petrochemical industries, since C₂H₂ impurities deactivate the catalysts and terminate the polymerization of C₂H₄. Carbon dioxide (CO₂) emission from power plants contributes to global climate change and threatens the survival of life on this planet. Herein, 2D crystalline polyimide porous organic framework PAF-120, which was constructed by imidization of linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and triangular 1,3,5-tris(4-aminophenyl)benzene, showed significant thermal and chemical stability. Low-pressure gas adsorption isotherms revealed that PAF-120 exhibits good selective adsorption of C₂H₂ over C₂H₄ and CO₂ over N₂. At 298 K and 1 bar, its C₂H₂ and CO₂ selectivities were predicted to be 4.1 and 68.7, respectively. More importantly, PAF-120 exhibits the highest selectivity for C₂H₂/C₂H₄ separation among porous organic frameworks. Thus PAF-120 could be a suitable candidate for selective separation of C₂H₂ over C₂H₄ and CO₂ over N₂.     

Mg-MOF-74对CO2/H2O的吸附性能

以Mg(NO₃)₂·6H₂O和2,5-二羟基对苯二甲酸为原料, 采用溶剂热法制备了金属有机骨架材料Mg-MOF-74. 利用X射线衍射(XRD)、 红外光谱(FTIR)和扫描电子显微镜(SEM)等测试手段对其结构、 形貌和性能进行了分析, 并利用自制穿透实验装置研究了产物吸附CO₂/H₂O的性能. 结果表明: 合成的样品纯度高, 结构完整, 形貌规则有序, 具有较高的CO₂吸附量. 双组分CO₂/H₂O穿透实验结果证实, 在水蒸气存在情况下, 与沸石13X相比, Mg-MOF-74仍具有较高的CO₂吸附能力, 可用于分离高湿烟道气中的CO₂.     

Contactless Weighing Up to High Pressures For Analysing Adsorption And Density of Fluids

Adsorption of supercritical fluids methane, nitrogen and argon by active carbons was studied up to a pressure of 500 bar. A three-parameter isothermal equation was used to represent the adsorption equilibrium. This isothermal equation is based on a physical model conception which had already been used for the modelling of adsorption processes with a pressure up to 150 bar. Beside the exact knowledge of the measurable parameters pressure, temperature and fluid composition, the density of the adsorbate are essential for the evaluation of the adsorption analysis. The fluid density can be determined either via equations of state, which is normally the most practicable and fastest way, or via lift measurements of a lowering body in the fluid based on the principle of Archimedes. This work represents and discusses the question of to what extent the fluid density determined under real conditions via equations of state, using, for example, equation of Bender, corresponds to the fluid density measured under high-pressure. This revised version was published online in August 2006 with corrections to the Cover Date.     

Application of a magnetic suspension balance to the oxidation study of the zirconium based alloys under high pressure water vapour

The fuel claddings in the Pressurised Water Reactor are corroded in water at high temperature and high pressure. The technical device ableto follow continuously the corrosion rate in conditions close to this medium does not yet exist. That is the reason why a high pressure thermogravimetric installation based on magnetic suspension has been designed to study in situ the oxidation kinetics of the zirconium based alloys under water vapour until 50 bars of pressure at 415°C. The accuracy of measurements is about 5·10⁻⁵ g under 2 bars, and 10⁻⁴ g under 50 bars. The reproducibility of measurements was verified and the deviation regarding post test weighing at room temperature is around 5·10⁻⁵ g what is clearly satisfying. Finally, the results presented in this work allow validating the high pressure thermogravimetric measurements obtained with this magnetic suspension device.     

Adsorption of CO2 and H2 on Nitrogen-doped Porous Carbon from Ionic Liquid Precursor

Nitrogen-doped mesoporous carbon material was prepared via a simple one-step thermolysis method via the carbonization of ionic liquid, 1-cyanomethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([MCNIm]⁺[Nf₂T]^-). The nanostructure of the resultant carbon material was characterized by X-ray diffraction(XRD) and transmission electron microscopy(TEM) and the types of N-containing groups of the carbon material were investigated by X-ray photoelectron spectroscopy(XPS). The N-content of the carbon material is 18.6%(mass fraction) based on the elemental analysis. The produced mesoporous carbon material was further used as the solid sorbent for H₂ and CO₂. The hydrogen uptake capacity and H₂ isosteric heat of the carbon material were discussed. Furthermore, the nitrogen-containing carbon material as good sorbent shows relatively high adsorption and separation ability for CO₂ from CH₄, for which the heat of CO₂ adsorption(Q_st) is 31.8 kJ/mol. The mesoporous structure and nitrogen functionality make the carbon material with high adsorption capacity and selectivity for CO₂ and ability to store H₂, indicating that this kind of nitrogen-doped carbon material originated from ionic liquids is a promising sorbent material for high-performance separation and adsorption.     

Mixed Metal–Organic Framework with Multiple Binding Sites for Efficient C2H2/CO2 Separation

The separation of C₂H₂/CO₂ is particularly challenging owing to their similarities in physical properties and molecular sizes. Reported here is a mixed metal–organic framework (M′MOF), [Fe(pyz)Ni(CN)₄] ( FeNi‐M′MOF , pyz=pyrazine), with multiple functional sites and compact one‐dimensional channels of about 4.0 Å for C₂H₂/CO₂ separation. This MOF shows not only a remarkable volumetric C₂H₂ uptake of 133 cm³ cm^?3, but also an excellent C₂H₂/CO₂ selectivity of 24 under ambient conditions, resulting in the second highest C₂H₂‐capture amount of 4.54 mol L^?1, thus outperforming most previous benchmark materials. The separation performance of this material is driven by π–π stacking and multiple intermolecular interactions between C₂H₂ molecules and the binding sites of FeNi‐M′MOF . This material can be facilely synthesized at room temperature and is water stable, highlighting FeNi‐M′MOF as a promising material for C₂H₂/CO₂ separation.     

H2对Rh-Mn-Li-Ti/SiO2催化剂上CO吸附和脱附的影响

 应用红外光谱和程序升温脱附技术研究了Rh-Mn-Li-Ti/SiO2催化剂上H2对CO吸附和脱附的影响. 结果表明,预吸附的H2主要占据线式CO的吸附位. 共吸附时H2与CO在Rh位上形成了羰基氢化物,从而导致线式物种谱带红移,且高的H2浓度有利于CO的吸附. 在323 K下, H2对预吸附的CO谱带位置和强度没有影响. 但是,随着温度的升高, H2的存在促进了弱吸附CO的脱附,并使之重新吸附; 同时, H2促进了强吸附CO的解离,增强了CO的吸附强度和催化剂的吸附能力.     

Halogen–C2H2 Binding in Ultramicroporous Metal–Organic Frameworks (MOFs) for Benchmark C2H2/CO2 Separation Selectivity

Acetylene (C₂H₂) capture is a step in a number of industrial processes, but it comes with a high-energy footprint. Although physisorbents have the potential to reduce this energy footprint, they are handicapped by generally poor selectivity versus other relevant gases, such as CO₂ and C₂H₄. In the case of CO₂, the respective physicochemical properties are so similar that traditional physisorbents, such as zeolites, silica, and activated carbons cannot differentiate well between CO₂ and C₂H₂. Herein, we report that a family of three isostructural, ultramicroporous (<7 Å) diamondoid metal–organic frameworks, [Cu(TMBP)X] (TMBP=3,3′,5,5′-tetramethyl-4,4′-bipyrazole), TCuX (X=Cl, Br, I), offer new benchmark C₂H₂/CO₂ separation selectivity at ambient temperature and pressure. We attribute this performance to a new type of strong binding site for C₂H₂. Specifically, halogen ⋅⋅⋅ HC interactions coupled with other noncovalent in a tight binding site is C₂H₂ specific versus CO₂. The binding site is distinct from those found in previous benchmark sorbents, which are based on open metal sites or electrostatic interactions enabled by inorganic fluoro or oxo anions.     

Optimizing Fe-Based Metal-Organic Frameworks through Ligand Conformation Regulation for Efficient Dye Adsorption and C2H2/CO2 Separation

Regulating the structure of metal-organic frameworks (MOFs) by adjusting the ligands reasonably is expected to enhance the interaction of MOFs on special molecules/ions, which has significant application value for the selective adsorption of guest molecules. Herein, two tricarboxylic ligands H₃L−Cl and H₃L−NH₂ were designed and synthesized based on the ligand H₃TTCA by replacing part of the benzene rings with C=C bonds and modifying the chlorine and amino groups on the 4-position of the benzene ring. Two 3D Fe-MOFs ( UPC-60-Cl and UPC-60-NH₂ ) with the new topology types were constructed. As the C=C bonds of the ligands have flexible torsion angles, UPC-60-Cl features three types of irregular 2D channels, while UPC-60-NH₂ has a cage with two types of windows on the surface. The synergistic effect of unique channels and modification of functional groups endows UPC-60-Cl and UPC-60-NH₂ with high adsorption capacity for organic dyes. Compound UPC-60-Cl shows high adsorption capacity for CV (147.2 mg g⁻¹), RHB (100.3 mg g⁻¹), and MO (220.9 mg g⁻¹), whereas UPC-60-NH₂ exhibits selective adsorption of MO (158.7 mg g⁻¹). Meanwhile, based on the diverse pore structure and modification of active sites, UPC-60-Cl and UPC-60-NH₂ show the selective separation of equimolar C₂H₂/CO₂. Therefore, reasonable regulation of organic ligands plays a significant role in guiding the structure diversification and performance improvement of MOFs.     

Adsorption kinetics and thermodynamics of acid dyes on a carboxymethylated chitosan-conjugated magnetic nano-adsorbent

The monodisperse chitosan-conjugated Fe(3)O(4) nanoparticles with a mean diameter of 13.5 nm were fabricated by the carboxymethylation of chitosan and its covalent binding onto Fe(3)O(4) nanoparticles via carbodiimide activation. The carboxymethylated chitosan (CMCH)-conjugated Fe(3)O(4) nanoparticles with about 4.92 wt.-% of CMCH had an isoelectric point of 5.95 and were shown to be quite efficient as anionic magnetic nano-adsorbent for the removal of acid dyes. Both the adsorption capacities of crocein orange G (AO12) and acid green 25 (AG25), as the model compounds, decreased with increasing pH, and the decreasing effect was more significant for AO12. On the contrary, the increase in the ionic strength decreased the adsorption capacity of AG25 but did not affect, obviously, the adsorption capacity of AO12. By the addition of NaCl and NaOH, both AO12 and AG25 could desorb and their different desorption behavior could be attributed to the combined effect of pH and ionic strength. From the adsorption kinetics and thermodynamics studies, it was found that both the adsorption processes of AO12 and AG25 obeyed the pseudo-second-order kinetic model, Langmuir isotherm, and might be surface reaction-controlled. Furthermore, the time required to reach the equilibrium for each one was significantly shorter than those using the micro-sized adsorbents due to the large available surface area. Also, based on the weight of chitosan, the maximum adsorption capacities were 1 883 and 1 471 mg x g(-1) for AO12 and AG25, respectively, much higher than the reported data. Thus, the anionic magnetic nano-adsorbent could not only be magnetically manipulated but also possessed the advantages of fast adsorption rate and high adsorption capacity. This could be useful in the fields of separation and magnetic carriers. [formula in text].     

Porous Mn2+ Magnet with a Pt−Cl Framework: Correlation between Water Vapor Adsorption/Desorption and Slow Magnetic Relaxation

We report the water adsorption/desorption behavior and dynamic magnetic properties of the Pt−Cl chain complex [{[Pt(en)₂][PtCl₂(en)₂]}₃][{(MnCl₅)Cl₃}₂] ⋅ 12H₂O ( 1 ). Upon heating 1 in a vacuum, we obtained the dehydrated form [{[Pt(en)₂][PtCl₂(en)₂]}₃][{(MnCl₅)Cl₃}₂] ( 1DH ). The framework structures of 1 and 1DH are identical, and both complexes underwent slow magnetic relaxation. However, the magnetic relaxation times for 1DH were shorter than those for 1 , meaning that the dynamic magnetic properties were controlled upon water vapor adsorption/desorption. From detailed analyses of the dynamic magnetic behavior, a phonon-bottleneck effect contributes to the magnetic relaxation processes. We discuss the mechanism for the changes in the magnetic relaxation processes upon dehydration in terms of the heat capacity and thermal conductivity.     

磁性壳聚糖复合微球的制备及其Cu2+吸附性能

以球磨后的粉煤灰磁珠（MS）颗粒为磁核,通过溶胶凝胶法和反相微乳液法依次包覆SiO₂和壳聚糖（CS）,制备了MS@SiO₂@CS磁性微球。利用扫描电镜及能量色散谱仪、热重分析仪、红外光谱仪、X射线衍射仪、振动样品磁强计对所得样品的结构和磁性进行了系统表征。结果表明,磁珠颗粒表面实现了逐层包覆,较均匀的分散于壳聚糖基体中,MS@SiO₂@CS微球的比饱和磁化强度可达7.04 emu·g^-1。Cu²⁺离子吸附实验表明,所得磁性壳聚糖微球对Cu²⁺具有良好的吸附能力,最大吸附量可达11.08 mg·g^-1;而且可通过磁选法高效固液分离。吸附动力学研究表明,MS@SiO₂@CS微球对Cu²⁺离子的吸附符合准二级动力学模型,以化学吸附为主。     

H2、CO、CH4混合气体爆炸极限的多元回归分析

H2,CO,CH4是化工生产中常遇到的混合气体,若与空气混合,一定条件下就构成多元爆炸性混合气体,浓度爆炸极限是一个关键性数据。对于多元可燃性混合气体,主要采用Le Chatelier经验方程或对其进行改进后的公式进行估算,但Chatelier经验方程只适用于烃类的混合气体与空气的混合物,对于含氢的多元爆炸性混合气体,预测误差很大。本文对大量的浓度爆炸极限数据进行了多元线性回归分析,建立了爆炸极限预测模型,对于指导多元混合气体支链燃烧与爆炸的理论研究和实践,具有一定的参考价值。     

Dynamic Adsorption of H2S onto a Goethite-Based Material

The use of adsorption technology to remove H₂S from synthetic gas (H₂S and N₂) using a goethite-based adsorbent was investigated. The influence of the H₂S feed concentration (150–600 mg), the adsorbent dosage (1–4 g), and the gas flow rate (210–540 cm³/min) on the breakthrough curves and H₂S adsorption on the adsorbent at the breakthrough point was investigated. Dynamic column experiments were performed to provide data for the theoretical models and to verify the performance of the system in the adsorption process. The theoretical models used in the present work were found to predict the adsorption breakthrough performance reasonably well.     

磁性壳聚糖复合微球的制备及其Cu~(2+)吸附性能

以球磨后的粉煤灰磁珠(MS)颗粒为磁核,通过溶胶凝胶法和反相微乳液法依次包覆SiO_2和壳聚糖(CS),制备了MS@SiO_2@CS磁性微球。利用扫描电镜及能量色散谱仪、热重分析仪、红外光谱仪、X射线衍射仪、振动样品磁强计对所得样品的结构和磁性进行了系统表征。结果表明,磁珠颗粒表面实现了逐层包覆,较均匀的分散于壳聚糖基体中,MS@SiO_2@CS微球的比饱和磁化强度可达7.04 emu·g~(-1)。Cu~(2+)离子吸附实验表明,所得磁性壳聚糖微球对Cu~(2+)具有良好的吸附能力,最大吸附量可达11.08 mg·g~(-1);而且可通过磁选法高效固液分离。吸附动力学研究表明,MS@SiO_2@CS微球对Cu~(2+)离子的吸附符合准二级动力学模型,以化学吸附为主。     

捕集高湿烟气中CO2的变压吸附技术

变压吸附法在捕集烟气中的CO₂这一领域中显示出强大的优越性,但实际电厂烟气含有少量的水蒸气,这对利用常规吸附剂捕集CO₂造成很大挑战。为解决上述瓶颈问题,改进变压吸附工艺以及开发对湿度不敏感、高效的吸附剂成为最主要的途径。本文详细介绍了两种常用的变压吸附工艺,即多层变压吸附及微波辅助真空再生法分离高湿烟气的研究进展,综述了近年来研发的适于捕集高湿烟气的高效吸附剂,系统阐述了各种吸附剂的物理化学特性及其吸附CO₂、H₂O的机制,并在此基础上讨论了变压吸附技术捕集高湿烟气时存在的问题,提出了研究展望。相信随着人们对变压吸附工艺的改进以及对新型高效吸附剂的进一步研发,必将显著降低捕集高湿烟气中CO₂的成本,这将对燃煤电厂等高湿CO₂排放源的温室气体减排具有重要意义。