氨基功能化的金属有机框架与模型燃油中含氮化合物的结合作用

合成了金属有机骨架MIL-53(Al)和MIL-53(Al)-NH_2,并且将其作为吸附剂去除油品中的含氮化合物(喹啉和吡咯)。采用X射线衍射(XRD)、扫描电镜(SEM)、FT-IR光谱以及热重分析等对两种吸附剂进行了表征。结果表明,MIL-53(Al)-NH_2能够快速地吸附油品中的喹啉/吡咯并且显示了较高的吸附容量,但MIL-53(Al)对喹啉/吡咯的吸附容量较低,原因是MIL-53(Al)-NH_2和喹啉之间存在有利的氢键结合,但MIL-53(Al)-NH_2与吡咯的氢键作用相对较低。研究了影响吸附容量的因素,包括吸附时间和温度。采用准一级和准二级动力学模型拟合了喹啉和吡咯的吸附数据,研究了MIL-53(Al)-NH_2对喹啉和吡咯的吸附等温线和吸附热力学。通过简单的溶剂洗涤使得MIL-53(Al)-NH_2再生,并重新用于吸附过程。     

金属-有机骨架MIL-101(Cr)掺杂聚合物整体柱的制备及其用于酚类化合物的在线固相萃取

制备了金属-有机骨架（MOF）MIL-101（Cr）掺杂聚合物整体柱，建立了在线固相萃取-高效液相色谱检测水中4-硝基苯酚、2-硝基苯酚、3-甲基苯酚和2，4-二氯苯酚的方法。考察了样品溶液pH值、上样时间、上样流速和解吸时间对酚类化合物萃取效果的影响。在最优萃取条件下，采用制备的整体柱检测水中酚类化合物，其富集因子高，线性范围宽，精密度好，检出限低，适用于水中酚类化合物的检测。制备掺杂聚合物整体柱是促进和拓宽MOFs在线固相萃取应用的有效方法之一。     

单宁酸修饰的超高交联吸附树脂对酚类化合物的吸附研究

通过氯甲基化的苯乙烯-二乙烯苯共聚物的后交联及单宁酸的化学修饰反应制备了单宁酸修饰的超高交联吸附树脂(TAMR),通过红外光谱、元素分析、扫描电镜和比表面孔径分析对TAMR树脂的结构特征和表面参数及形貌进行表征.通过等温吸附实验和吸附动力学实验研究了苯酚、对硝基苯酚和对氯苯酚在TAMR树脂上的吸附性能和吸附机理.结果表明,TAMR树脂具有较高的比表面积(780.1 m2/g)和较丰富的微孔(482.3 m2/g),树脂表面修饰了较丰富的羟基.TAMR树脂对苯酚、对硝基苯酚和对氯苯酚均具有较好的吸附性能,288 K时吸附量分别可达1.43、2.07和2.48 mmol/g(c0为500 mg/L).3种酚类化合物在TAMR树脂上的吸附为典型的物理吸附,其吸附焓变和熵变均为负值.当酚类化合物以分子形态存在时,有利于其被TAMR树脂吸附.Langmuir和Freundlich方程均能较好地拟合酚类化合物在TAMR树脂上的吸附等温线.吸附动力学过程符合准一级动力学方程,颗粒内扩散过程是TAMR树脂吸附这3种酚的吸附速率的主要控制步骤.     

间氨基水杨酸修饰超高交联吸附树脂对酚类化合物的吸附行为

合成间氨基水杨酸修饰的超高交联吸附树脂LZ-01,比较LZ-01树脂与NJ-8树脂对对甲基苯酚和对硝基苯酚的吸附能力,研究LZ-01树脂在不同温度(288K,313K,318K)下吸附水溶液中对甲基苯酚和对硝基苯酚的静态吸附热力学和动力学行为。结果表明,由于LZ-01树脂具有更大的比表面积、更多的微孔且含有氨基、羟基和羧基等基团,使其对对甲基苯酚和对硝基苯酚的吸附量明显高于NJ-8树脂。Freundlich方程对等温吸附数据能够很好地拟合,吸附焓变绝对值小于40kJ/mol,表明吸附是焓驱动的物理吸附过程。LZ-01树脂对对甲基苯酚和对硝基苯酚吸附动力学均符合准一级动力学方程,吸附速率随温度升高而增大,颗粒内扩散是该吸附过程的速控步骤。     

溶剂热条件对MIL-53(Fe)结晶度及吸附性能的影响

采用溶剂热法制备一系列金属有机骨架材料MIL-53(Fe),使用傅立叶变换红外光谱仪、X射线衍射仪、电子扫描电镜等表征手段对其结构进行表征.探讨了其对有机染料亚甲基蓝的吸附性能.通过改变反应温度来调控MIL-53(Fe)的结晶度,结果表明,高结晶度的MIL-53(Fe)更利于吸附行为.吸附动力学、等温线研究表明,该吸附过程符合准二级动力学和Langmuir等温线模型.     

羟肟酸型吸附树脂对苯酚的吸附性能

通过水杨羟肟酸(SHA)与氯甲基化交联聚苯乙烯微球之间的Friedel-Crafts烷基化反应,实现了SHA在交联聚苯乙烯微球(CPS)上的固载化,制得了SHA功能化微球SHA-CPS。采用红外光谱对其结构进行表征;通过吸附动力学实验和等温吸附实验研究了SHA-CPS微球对苯酚及对硝基苯酚的吸附行为,考察了介质的pH、温度对SHA-CPS微球吸附苯酚的影响,探讨了其吸附热力学与吸附机理。结果表明,SHA-CPS对苯酚及对硝基苯酚具有较强的吸附能力和较快的吸附速率,其吸附能力受温度和pH影响较大。SHA-CPS对苯酚及对硝基苯酚的吸附动力学过程符合准一级方程,其吸附行为符合Freundich吸附模型,属单分子层吸附。SHA-CPS吸附树脂具有良好的重复使用性能。     

超高效液相色谱-串联质谱法测定染发剂中7种酚类化合物

提出了应用超高效液相色谱-串联质谱法同时测定染发剂中4-氨基-2-硝基苯酚、3-二乙氨基酚、2-氨基-4-氯苯酚、2-氨基-5-硝基苯酚、2-氨基-3-硝基苯酚、1,7-二羟基萘酚和2,3-二羟基萘酚等7种酚类化合物的方法。采用甲醇萃取染发剂中酚类成分,经WatersAcquityUPLCTMBEHC18色谱柱分离,外标法定量,多反应监测模式采集质谱数据。7种酚类化合物的检出限(3S/N)均低于50.0μg.L-1。在10,20,50μg.g-1三个添加水平下,7种酚类化合物的回收率在68.8%～112.5%之间,相对标准偏差(n=6)在1.58%～12.61%之间。     

活性炭吸附对硝基苯酚的动力学和热力学研究

以生物质废弃物枣核为原料,通过Zn Cl2活化法制备了活性炭,采用低温N2吸附、FT-IR等对活性炭性能进行了表征。将该活性炭用于吸附对硝基苯酚,考察了吸附温度、溶液初始浓度等因素对吸附的影响,并对吸附动力学、热力学及吸附机理进行了研究。研究表明,枣核活性炭主要为微孔兼有一定中孔结构,比表面积为1096m2/g,平均孔径为2.2nm。该活性炭吸附对硝基苯酚的过程是一个快速吸附的过程,20min内吸附达平衡,符合准二级动力学模型;采用Toth和Redlich-Peterson模型描述对硝基苯酚在活性炭上的吸附更合适;热力学研究表明,该吸附过程为自发、吸热且体系混乱度减小的过程。利用生物质废弃物枣核制备活性炭并用于对硝基苯酚的吸附,具有一定的经济价值,实现以废治废的目的。     

烯基离子液体为单体的磁性分子印迹聚合物及其用于酚类化合物的萃取和检测

以3-(甲基丙烯酰氧)丙基三甲氧基硅烷修饰的Fe3O4为载体,乙二醇二甲基丙烯酸酯为交联剂,4-硝基苯酚为模板分子,烯基离子液体1-乙烯基-3-乙基咪唑四氟硼酸盐为功能单体制备了磁性分子印迹聚合物(IL-MMIP),采用透射电镜、红外光谱和磁强计对磁性分子印迹聚合物进行表征,结果表明磁性载体表面成功地包覆了分子印迹聚合物层。IL-MMIP对4-硝基苯酚的吸附在10 min达到平衡,最大饱和吸附量达到20.98μmol/g。对比磁性非印迹聚合物,IL-MMIP对4-硝基苯酚具有较高的选择吸附性能。IL-M M IP萃取-高效液相色谱法对4-硝基苯酚、2-硝基苯酚、苯酚、间甲酚等4种酚类化合物进行检测,检测限在0.2~1.7μg/L。方法应用于自来水、嘉兴南湖水、焦化厂废水等实际样品中酚类化合物的检测,加标回收率在85.7%~100.5%。     

中心切割GC-MS法分析煤液化油中的酚类化合物

使用碱洗提酚法提取煤液化油中的酚类化合物,然后结合Deans Switch装置和LTM色谱柱模块,采用中心切割气相色谱(GC)-质谱(MS)法对提取的酚类化合物进行定性。采用GC建立标准曲线,对煤液化油中主要酚类化合物的质量分数进行测定,并测定了煤液化油中邻甲基苯酚、2-乙基苯酚、4-丙基苯酚和5-茚酚4种酚类化合物的加标回收率。结果表明,在煤液化油中共定性出51种酚类化合物,测定了其中的35种酚类化合物的质量分数,其量占煤液化油总量的2.54(wt)%,苯酚和烷基苯酚占35种酚类化合物的88.2(wt)%。煤液化油中4种酚类化合物的加标回收率高,重复性好。     

D301树脂对酚类的吸附热力学研究

测定D301树脂对环己烷溶液中苯酚的吸附等温线，利用热力学函数关系计算了等量吸附焓，吸附自由能和吸附熵，等量吸附焓在30kJ/mol-35kJ/mol之间，推测吸附过程为氢键吸附。比较D301树脂对水溶液和环己烷溶液中苯酚的吸附性能，及D301树脂对环己烷溶液中苯酚和邻硝苯酚的吸附性能，进一步讨论了D301树脂对酚类物质吸附中的氢键作用。     

Adsorption of CO2 in metal organic frameworks of different metal centres: Grand Canonical Monte Carlo simulations compared to experiments

A Grand Canonical Monte Carlo study has been performed in order to compare the different CO₂ adsorption mechanisms between two members of the MIL-n family of hybrid metal-organic framework materials. The MIL-53 (Al) and MIL-47 (V) systems were considered. The results obtained confirm that there is a structural interchange between a large pore and narrow pore forms of MIL-53 (Al), not seen with the MIL-47 (V) material, which is a consequence of the presence of μ ₂-OH groups. The interactions between the CO₂ molecules and these μ ₂ OH groups mainly govern the adsorption mechanism in this MIL-53 (Al) material. The subsequent breaking of these adsorption geometries after the adsorbate loading increases past the point where no more preferred adsorption sites are available, are proposed as key features of the breathing phenomenon. After this, any new adsorbates introduced into the MIL-53 (Al) large pore structure experience a homogeneous adsorption environment with no preferential adsorption sites in a similar way to what occurs in MIL-47 (V).     

Study of selective adsorption of aromatic compounds from solutions by the flexible MIL-53(Al) metal-organic framework

The dynamic method under conditions close to equilibrium was applied to study the liquid-phase adsorption in the Henry region for a series of aromatic compounds on the MIL-53(Al) metal-organic framework at different temperatures. The interpretation of the obtained experimental adsorption data was based on the TOPOS analysis of the structure of the cavities in the MIL-53(Al) framework using the Voronoi—Dirichlet polyhedra concept. It is shown that the adsorption activity of the investigated material under the liquid-phase conditions is governed by a possible expansion of the channels and cavities in the structure and by a breathing effect of the structure caused by the temperature variation. The selectivity of adsorption shown by MIL-53(Al) for a series of the studied compounds is due to the adsorbate—adsorbent π—π-interaction and hydrogen bonding of adsorbate molecules with Brönsted acid sites of the metal-organic framework. High adsorption selectivity of the MIL-53(Al) framework were found for compounds differed in the number of aromatic rings in the molecule and the presence of the methyl substituent, as well as for aromatic hydrocarbons and their sulfur-containing heterocyclic analogs.     

Thermodynamics of adsorption of aromatic compounds from non-aqueous solutions by MIL-53(Al) metal-organic framework

The thermodynamics of adsorption of mono-, di-, and tricyclic aromatic compounds by MIL-53(Al) metal-organic framework from their solutions in MeCN, MeOH and n-C₆H₁₄–PrⁱOH was studied for the first time. It was found that the adsorption of the test substances from solutions in MeCN and MeOH is characterized by positive values of enthalpy and entropy changes, and the adsorption from n-C₆H₁₄–PrⁱOH medium is characterized by negative enthalpy and entropy changes. Upon adsorption by MIL-53(Al) framework from polar media, aromatic compounds were proposed to transfer from the liquid phase with a higher degree of association into the solvent medium with a lower degree of association, molecules of which are disordered due to the strong interaction with the hydrophobic walls of the framework pores. It was concluded that the driving force of adsorption by MIL-53(Al) from MeCN and MeOH is increase in entropy of the system, while the factor of adsorption from n-C₆H₁₄–PrⁱOH medium is decrease in enthalpy of the adsorption system. The compensation effect in liquid-phase adsorption of aromatic compounds by MIL-53(Al) framework was discovered. The effect of the liquid phase nature on selectivity of adsorption from solutions onto investigated metal-organic framework was demonstrated.     

Separation of styrene and ethylbenzene on metal-organic frameworks: analogous structures with different adsorption mechanisms

The metal-organic frameworks MIL-47 (V(IV)O{O(2)C-C(6)H(4)-CO(2)}) and MIL-53(Al) (Al(III)(OH)·{O(2)C-C(6)H(4)-CO(2)}) are capable of separating ethylbenzene and styrene. Both materials adsorb up to 20-24 wt % of both compounds. Despite the fact that they have identical building schemes, the reason for preferential adsorption of styrene compared to ethylbenzene is very different for the two frameworks. For MIL-47, diffraction experiments reveal that styrene is packed inside the pores in a unique, pairwise fashion, resulting in separation factors as high as 4 in favor of styrene. These separation factors are independent of the total amount of adsorbate offered. This is due to co-adsorption of ethylbenzene in the space left available between the packed styrene pairs. The separation is of a non-enthalpic nature. On MIL-53, the origin of the preferential adsorption of styrene is related to differences in enthalpy of adsorption, which are based on different degrees of framework relaxation. The proposed adsorption mechanisms are in line with the influence of temperature on the separation factors derived from pulse chromatography: separation factors are independent of temperature for MIL-47 but vary with temperature for MIL-53. Finally, MIL-53 is also capable of removing typical impurities like o-xylene or toluene from styrene-ethylbenzene mixtures.     

High-performance liquid chromatographic separation of position isomers using metal-organic framework MIL-53(Al) as the stationary phase

Metal-organic framework MIL-53(Al) was explored as the stationary phase for high-performance liquid chromatographic separation of position isomers using a binary and/or polar mobile phase. Baseline separations of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers were achieved on the slurry-packed MIL-53(Al) column with high resolution and good precision. The effects of mobile phase composition, injected sample mass and temperature were investigated. The separation of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers on MIL-53(Al) were controlled by entropy change.     

金属有机骨架材料MIL-53(Al)负载纳米Pd颗粒：一种CO氧化的活性催化剂

通过等体积浸渍法制备了金属有机骨架材料MIL-53(Al) (MIL：Materials of Institut Lavoisier)负载纳米Pd催化剂. 采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对催化剂的结构进行了表征. 催化剂在反应前后XRD衍射峰保持不变,说明载体MIL-53(Al)具有良好的稳定性. 采用TEM对催化剂进行表征,结果表明,MIL-53(Al)的多孔晶体结构有助于形成高度分散的纳米Pd颗粒,样品2.7% (w) Pd/MIL-53 中Pd颗粒的平均粒径为2.21 nm. 该催化剂在CO氧化反应中表现出较高的催化活性,115 ℃达到完全转化. 同时催化剂可循环使用,多次反应后催化活性和催化剂结构都保持稳定.     

Incorporation of metallocenes into the channel structured Metal-Organic Frameworks MIL-53(Al) and MIL-47(V)

A selection of metallocene inclusion compounds with channel structured MOFs (MOF = Metal-Organic Framework) were obtained via solvent-fee adsorption of the metallocenes from the gas-phase. The adsorbate structures ferrocene(0.5)@MIL-53(Al) (MIL-53(Al) = [Al(OH)(bdc)](n) with bdc = 1,4-terephthalate), ferrocene(0.25)@MIL-47(V) (MIL-47(V) = [V(O)(bdc)](n)), cobaltocene(0.25)@MIL-53(Al), cobaltocene(0.5)@MIL-47(V), 1-formylferrocene(0.33)@MIL-53(Al), 1,1'dimethylferrocene(0.33)@MIL-53(Al), 1,1'-diformylferrocene(0.5)@MIL-53(Al) were determined from powder X-ray diffraction data and were analyzed concerning the packing and orientation of the guest species. The packing of the ferrocene guest molecules inside MIL-47(V) is significantly different compared to MIL-53(Al) due to the lower breathing effect and weaker hydrogen bonds between the guest molecules and the host network in the case of MIL-47(V). The orientation of the metallocene molecule is also influenced by the substituents (CH(3) and CHO) at the cyclopentadienyl ring and the interaction with the bridging OH group of MIL-53(Al). The inclusion of redox active cobaltocene into MIL-47(V) leads to the formation of a charge transfer compound with a negatively charged framework. The reduction of the vanadium centers is stoichiometric. The resulting material is a mixed valence compound with a V(3+)/V(4+) ratio of 1:1. The new compounds were characterized via thermal gravimetric analysis, infrared spectroscopy, solid state NMR, and differential pulse voltammetry. Both systems are 1D-channel pore structures. The metallocene adsorbate induced breathing effect of MIL-53(Al) is more pronounced compared to MIL-47(V), this can be explained by the different bridging groups between the MO(6) clusters.     

Selective adsorption and separation of ortho-substituted alkylaromatics with the microporous aluminum terephthalate MIL-53

The metal-organic framework MIL-53(Al) was tested for selective adsorption and separation of xylenes and ethylbenzene, ethyltoluenes, and cymenes using batch, pulse chromatographic, and breakthrough experiments. In all conditions tested, MIL-53 has the largest affinity for the ortho-isomer among each group of alkylaromatic compounds. Separations of the ortho-compounds from the other isomers can be realized using a column packed with MIL-53 crystallites. As evidenced by Rietveld refinements, specific interactions of the xylenes with the pore walls of MIL-53 determine selectivity. In comparison with the structurally similar metal-organic framework MIL-47, the selectivities among alkylaromatics found for MIL-53 are different. Separation of ethyltoluene and cymene isomers is more effective on MIL-53 than on MIL-47; the pores of MIL-53 seem to be a more suitable environment for hosting the larger ethyltoluene and cymene isomers than those of MIL-47.     

Remarkable adsorptive performance of a metal-organic framework, vanadium-benzenedicarboxylate (MIL-47), for benzothiophene

Liquid-phase adsorption of benzothiophene over isotypic MOFs such as MIL-47 and MIL-53(Al, Cr) has shown that a metal ion of a MOF-type material has a dominant role in adsorptive desulfurization and MIL-47 has a remarkable performance.