Catalytic properties of the Cr-HMS materials in the benzylation of benzene with benzyl chloride

A series of chromium-containing mesoporous silicas with different Cr contents were prepared and characterized with chemical analysis, N₂ adsorption measurements (BET equation and BJH theory), X-ray diffraction, diffuse reflectance UV-visible and H₂-temperature programmed reduction techniques. Excellent results in benzylation of benzene and substituted benzenes employing benzyl chloride as the alkylating agent were obtained. The mesoporous chromium-containing materials showed both high activity and high selectivity for benzylation of benzene. The activity of these catalysts for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > anisole. Kinetics of the benzene benzylation over these catalysts has also been investigated.     

Zinc-containing mesoporous silicas as a catalyst for the benzylation of benzene and other aromatics by benzyl chloride

The benzylation of benzene and the substituted benzenes reaction employing benzyl chloride as the alkylating agent over a series of zinc-containing mesoporous silicas with different Zn contents have been investigated. These materials (Zn-HMS-n) have been characterized by chemical analysis, BET, and XRD. The mesoporous zinc-containing materials showed both high activity and high selectivity for benzylation of benzene. The activity of these catalysts for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > anisole. The kinetics of the benzene benzylation over these catalysts has also been investigated. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 3, pp. 421–425.     

Adsorption of volatile organic compounds in porous metal–organic frameworks functionalized by polyoxometalates

The functionalization of porous metal–organic frameworks (Cu₃(BTC)₂) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N₂ and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols (C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies estimated by the modified Clausius–Clapeyron equation provided insight into the impact of POMs and alkali metal cations on the adsorption of VOCs. The introduction of POMs not only improved the stability, but also brought the increase of adsorption capacity by strengthening the interaction with gas molecules. Furthermore, the exchanged alkali metal cations acted as active sites to interact with adsorbates and enhanced the adsorption of VOCs.     

Synthesized high-silica hierarchical porous ZSM-5 and optimization of its reaction conditions in benzene alkylation with methanol

41.4% yield of xylene was obtained over high-silica hierarchical ZSM-5 catalyst by optimizing reaction conditions of benzene alkylation with methanol.     

Selective gas sorption in a [2+3] 'propeller' cage crystal

A [2+3] organic cage compound based on the condensation reaction of 1,3,5-tri(4-formylphenyl)benzene with 1,5-pentanediamine was synthesized. The resulting porous molecular crystal demonstrates selective adsorption of hydrogen and carbon dioxide over nitrogen. As for porous polymer membranes, a trade-off between sorption capacity and selectivity is observed for materials in this class.     

Highly Selective,High‐Capacity Separation of o‐Xylene from C8 Aromatics by a Switching Adsorbent Layered Material

Purification of the C₈ aromatics (xylenes and ethylbenzene) is particularly challenging because of their similar physical properties. It is also relevant because of their industrial utility. Physisorptive separation of C₈ aromatics has long been suggested as an energy efficient solution but no physisorbent has yet combined high selectivity (>5) with high adsorption capacity (>50 wt %). Now a counterintuitive approach to the adsorptive separation of o‐xylene from other C₈ aromatics involves the study of a known nonporous layered material, [Co(bipy)₂(NCS)₂]_n ( sql‐1‐Co‐NCS ), which can reversibly switch to C₈ aromatics loaded phases with different switching pressures and kinetics, manifesting benchmark o‐xylene selectivity (S_OX/EB≈60) and high saturation capacity (>80 wt %). Structural insight into the observed selectivity and capacity is gained by analysis of the crystal structures of C₈ aromatics loaded phases.     

Highly Selective,High‐Capacity Separation of o‐Xylene from C8 Aromatics by a Switching Adsorbent Layered Material

Purification of the C₈ aromatics (xylenes and ethylbenzene) is particularly challenging because of their similar physical properties. It is also relevant because of their industrial utility. Physisorptive separation of C₈ aromatics has long been suggested as an energy efficient solution but no physisorbent has yet combined high selectivity (>5) with high adsorption capacity (>50 wt %). Now a counterintuitive approach to the adsorptive separation of o‐xylene from other C₈ aromatics involves the study of a known nonporous layered material, [Co(bipy)₂(NCS)₂]_n ( sql‐1‐Co‐NCS ), which can reversibly switch to C₈ aromatics loaded phases with different switching pressures and kinetics, manifesting benchmark o‐xylene selectivity (S_OX/EB≈60) and high saturation capacity (>80 wt %). Structural insight into the observed selectivity and capacity is gained by analysis of the crystal structures of C₈ aromatics loaded phases.     

Factors affecting the sorption of Eu(III) on modified silica gel</p> </p>

Summary 8-Hydroxyquinoline in benzene, xylene, chloroform and toluene diluents was used to modify silica gel as a solid phase extractant (SPE) for the sorption of Eu(III) in batch extraction techniques. Influences of solid/liquid ratio, pH, metal ion concentration, particle size and temperature were studied. The optimum initial pH is 4.2, while the maximum sorption capacities for the prepared impregnated resins in benzene, xylene, chloroform and toluene diluents are 18.52, 14.98, 14.79 and 5.94 mg ^. g^-1, respectively. The sorption process is found to be affected by both metal ion concentration and particle size of the impregnated resin. Thermodynamic parameters for the sorption of Eu(III) were determined and the reaction is found to be exothermic and spontaneous with enthalpy-14.23 and-23.71 kJ ^. mol^-1 for benzene and xylene as diluents. Release of the element from the loaded solid particles into 0.01M HNO₃ is@85% and@53% from 8-HQ/benzene/silica gel and 8-HQ/xylene/silica gel.</p> </p>     

High benzene selectivity of mesoporous silicate for BTX gas sensing microfluidic devices

The gas selectivities of highly ordered mesoporous silicates and commercially-obtained porous silicates with respect to benzene, toluene and xylene were studied. After studying the porosities, pore uniformities, and surface silanol structures of the silicates and their relationships to gas selectivity in detail, we found that we could achieve high benzene selectivity by controlling the micropore size (less than 1 nm). Concluding that mesoporous silicate has a suitable micropore size and structure for benzene selectivity, we also observed that mesoporous silicate SBA-16 exhibited a high (>6) benzene selectivity from toluene and xylene even in a pseudo-atmospheric environment. A benzene detection limit of about 100 ppb was achieved by introducing SBA-16 into a microfluidic device originally developed for the separate detection of benzene, toluene, and xylene gases.     

采用原位聚合法制备固相微萃取涂层的初步研究

采用一步原位合成法制备了新型有机多孔聚合物涂层，并对其进行了初步评价研究．观察了单体浓度对其所制备涂层的萃取容量的影响，并优化了合成浓度．同时，在分析水体基质中的苯系物时，证明了该涂层对苯系物等含苯环物质具有选择性吸附的能力．     

Tuning the adsorption and fluorescence properties of aminal‐linked porous organic polymers through N‐heterocyclic group decoration

Aiming at tuning the adsorption and fluorescence properties of targeted porous organic polymer, four new aminal‐linked porous organic polymers (NAPOPs) were synthesized through the reaction of 1,4‐Bis(4,6‐diamino‐s‐triazin‐2‐yl) benzene (BATB) with four kinds of aldehydes substituted with different N‐heterocyclic groups. Among the polymers, NAPOP‐3 decorated with 5‐phenyl‐tetrazole group shows the largest CO₂ adsorption capacity (2.52 mmol g^?1 at 273 K and 100 kPa) because of its relative large surface area, while NAPOP‐1 decorated with piperazine groups shows relative large CO₂/N₂ adsorption selectivity (77 at 273 K and 100 kPa), attributable to its large CO₂ adsorption heats and cabined pore (<4 Å). Meanwhile, NAPOP‐1 and ?3 exhibit high adsorption rate toward iodine with a high capacity (>240 wt %). In addition, different luminescence emissions were also observed for NAPOPs, indicating different intramolecular charger transfer occurred inside polymer networks. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1724–1730     

Recognition of benzene, toluene and xylene using TGS array integrated with linear and non-linear classifier

Three volatile organic compounds (VOCs): benzene, toluene and xylene were measured with an array of six Taguchi gas sensors in the air with variable humidity content. The recognition of single compounds was performed, based on measurement results. The principal component analysis (PCA) pointed at humidity as the main classification factor in the measurement data set. The linear discriminant analysis (LDA) was applied to overcome this drawback and enforce classification with respect to benzene, toluene or xylene. It was shown that discriminant function analysis (DFA), which is an LDA method allowed for 100% success rate in test samples recognition of benzene. It did not allow for accurate recognition of test samples of toluene or xylene. Following, the non-linear classifier, radial basis function neural network (RBFNN) was applied. A specific configuration of input ‘s was found, which provided for successful recognition of each single compound: benzene, toluene or xylene in air with variable humidity content.     

漆酚醛树脂多孔微球对有机物的吸附性能

研究了由悬浮缩聚法制备的多孔漆酚醛树脂微球对乙二胺、二乙烯三胺和茶碱,以及苯、二甲苯、氯仿和四氯化碳等气体的吸附性能,并研究了吸附时间对乙二胺、二乙烯三胺和茶碱吸附性能的影响。结果表明,树脂中的酚羟基因能与胺基产生酸碱之间的作用而吸附乙二胺和二乙烯三胺,其吸附量分别为320.9mg/g、222.2mg/g;该多孔微球亦能吸附有机物气体,尤其对氯仿、四氯化碳的吸附性能较佳,其吸附量分别为248.1mg/g和119.7mg/g。     

金属有机骨架材料在吸附分离大气污染物中的应用

大气污染问题是关系人民生命健康和经济社会和谐发展的重大问题.因此需要开发高效的吸附材料用于大气污染物的吸附和分离.金属有机骨架材料(MOFs)是一类新型的多孔材料,该材料具有结构多样、孔结构有序、大比表面积和高孔隙率等结构特点.MOFs通过调节有机配体的长度和官能团调节孔径和孔道尺寸,并进行功能化修饰在孔道中引入功能性...     

New polypyrrole–carbon nanotubes–silicon dioxide solid‐phase microextraction fiber for the preconcentration and determination of benzene,toluene, ethylbenzene,and o‐xylene using gas liquid chromatography

For the first time, a polypyrrole–carbon nanotubes–silicon dioxide composite film coated on a steel wire was prepared by an electrochemical method. Scanning electron microscopy images showed that this composite film was even and porous. The prepared fiber was used as an absorbent for the headspace solid‐phase microextraction of benzene, toluene, ethylbenzene, and o‐xylene, followed by gas chromatographic analysis. This method presented an excellent performance, which was much better than that of a polypyrrole–carbon nanotube fiber. It was found that under the optimized conditions, the linear ranges were 0.01–200 ng/mL with correlation coefficients >0.9953, the detection limits were 0.005–0.020 ng/mL, the relative standard deviations were 3.9–6.4% for five successive measurements with a single fiber, and the reproducibility was 5.5–8.5% (n = 3). Finally, the developed method was successfully applied to real water samples, and the relative recoveries obtained for the spiked water samples were from 91.0 to 106.7%.     

Separation of Xylene Isomers in the Anion-Pillared Square Grid Material SIFSIX-1-Cu

Xylene isomer separation is considered one of the seven separation challenges that changed the world. In addition, the high-energy demand of xylene separation highlights the need for efficient novel adsorbents. Herein, the liquid-phase separation potential of the anion-pillared hybrid material SIFSIX-1-Cu was studied for preferential adsorption of o-xylene and m-xylene over p-xylene, which was inspired by a previous complexation crystallization method for separating m-xylene. We report detailed experimental liquid-phase adsorption experiments, yielding selectivities of 3.0 for o-xylene versus p-xylene and 2.6 for m-xylene versus p-xylene. Our theoretical calculations thus provide a reasonable explanation that the xylene adsorption selectivity is attributed to the C−H⋅⋅⋅F interaction, and the host–guest interaction order agrees with the adsorption priority: o-xylene > m-xylene > p-xylene.     

Simultaneous determination of benzene,toluene, ethylbenzene,and xylene metabolites in human urine using electromembrane extraction combined with liquid chromatography and tandem mass spectrometry

For the first time, electromembrane extraction combined with liquid chromatography and tandem mass spectrometry was applied for the determination of urinary benzene, toluene, ethylbenzene, and xylene metabolites. S‐Phenylmercapturic acid, hippuric acid, phenylglyoxylic acid, and methylhippuric acid isomers were extracted from human urine through a supported liquid membrane consisting of 1‐octanol into an alkaline acceptor solution filling the inside of a hollow fiber by application of an electric field. Various extraction factors were investigated and optimized using response surface methodology, the statistical method. The optimum conditions were established to be 300 V applied voltage, 15 min extraction time, 1500 rpm stirring speed, and 5 mM ammonium acetate (pH 10.2) acceptor solution. The method was validated with respect to selectivity, linearity, accuracy, precision, limit of detection, limit of quantification, recovery, and reproducibility. The results showed good linearity (r² > 0.995), precision, and accuracy. The extract recoveries were 52.8–79.0%. Finally, we applied this method to real samples and successfully measured benzene, toluene, ethylbenzene, and xylene metabolites.     

Arene Selectivity by a Flexible Coordination Polymer Host

The coordination polymers [Ag₄(O₂CCF₃)₄(phen)₃] ? phen ? arene ( 1? phen ? arene) (phen=phenazine; arene=toluene, p‐xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o‐xylene and m‐xylene as the solvent yield the solvent‐free coordination polymer [Ag₄(O₂CCF₃)₄(phen)₂] ( 2 ). Toluene, p‐xylene and benzene have been successfully used in mixed‐arene syntheses to template the formation of coordination polymers 1? phen ? arene, which incorporate o‐ or m‐xylene. The selectivity of 1? phen ? arene for the arene guests was determined, through pairwise competition experiments, to be p‐xylene>toluene≈benzene>o‐xylene>m‐xylene. The largest selectivity coefficient was determined as 14.2 for p‐xylene:m‐xylene and the smallest was 1.0 for toluene:benzene.     

Synthesis of core-shell material rich in carboxyl groups and its application in the selective adsorption of cationic peptides

The ability to extract peptides and proteins from biological samples with excellent reusability, high adsorption capacity, and great selectivity is essential in scientific research and medical applications. Inspired by the advantages of core-shell materials, we fabricated a core-shell material using amino-functionalized silica as the core. Benzene-1,3,5-tricarbaldehyde and 3,5-diaminobenzoic acid were used as model organic ligands to construct a shell coating by alternately reacting the two monomers on the surface of silica microspheres. The resultant material featured an outstanding capability for the adsorption of cationic peptides, most likely owing to its porous structure, a large number of carboxylic functional groups, and low mass-transfer resistance. The maximum saturated adsorption capacity reached 833.3 mg/g and the adsorption process took only 20 min. Under optimized adsorption conditions, the core-shell material was used to selectively adsorb cationic peptides from the tryptic digestive solution of lysozyme and bovine serum albumin, Specifically, the analysis results showed seven cationic peptides in the eluate and twenty anionic peptides in the supernatant, which indicates the efficient trap of most cationic peptides in the digestive solution.     

The alkylation reaction of benzene with methanol to produce toluene: Y-C and Y-CCs catalyst

The secondary reaction of toluene is difficult to be suppressed in benzene alkylation with methanol over conventional acidic zeolite catalysts. Moreover, the formation of coke yet remains a challenging problem. In this study, Na-Y zeolites were modified with ammonium carbonate (AC), citric acid (CA) and caesium nitrate(CN) to evaluate the alkylation of benzene with methanol, which was also characterized by XRD, SEM, FT-IR, N₂ adsorption and Py-IR. For the Na-Y treated with AC-CA-CN, not only the catalytic selectivity for the alkylation of benzene with methanol was improved (the total selectivity of toluene and xylene was 97.9% and toluene selectivity was 86.4%), but also the quantity of coke was greatly decreased.