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A gating ultramicroporous metal-organic framework showing high adsorption selectivity,capacity and rate for xylene separation

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Science China Chemistry 2022年第8期65卷 1552-1558页

作者： Zi-Ming Ye Xue-Feng Zhang De-Xuan Liu Yan-Tong Xu Chao Wang Kai Zheng Dong-Dong Zhou Chun-Ting He Jie-Peng Zhang Key Laboratory of Bioinorganic and Synthetic Chemistry(Ministry of Education) School of ChemistrySun Yat-Sen UniversityGuangzhou 510275China Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of Education/National Engineering Research Center for Carbohydrate Synthesis Jiangxi Normal UniversityNanchang 330022China 3.Guangdong Provincial Key Laboratory of New and Renewable Energy Research and DevelopmentGuangzhou Institute of Energy ConversionChinese Academy of SciencesGuangzhou 510640China

Adsorptive separation of p-xylene(pX)from xylene isomers is a key process in chemical industry,but known adsorbents cannot simultaneously achieve high adsorption selectivity,capacity,and rate.Here,we demonstrate gating ultramicropore as a solution for this challenge.Slight modification of the synthetic condition gives rise to isomeric metal-organic frameworksα-[Zn(pba)](MAF-88,H2pba=4-(1H-pyrazol-4-yl)benzoic acid)andβ-[Zn(pba)](MAF-89)possessing similar pillared-column structures,porosities,and high pX capacities of 2.0 mmol g^(−1),but very different framework/pore topologies,pore sizes,and pX selectivities.For binary and ternary mixtures of liquid xylene isomers,MAF-88 with narrow one-dimensional(1D)channels shows pX selectivity of 11 and 1.6,while MAF-89 with 3D-connected quasi-discrete pores shows pX selectivity up to 221 and 46,respectively.Thermogravimetry,differential scanning calorimetry,and time-dependent separation experiments reveal that the kinetic effects of the gating pores play more important roles than the thermodynamic effects,which is further confirmed by single-crystal X-ray diffraction and computational simulations.

关键词： metal-organic frameworks gating xylene adsorption separation

Occupational Health Risk Assessment of Benzene,Toluene,and xylene in Shanghai

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Biomedical and Environmental Sciences 2021年第4期34卷 290-298页

作者： WANG Tong Shuai SONG Bo SUN Qing Hua LIN Yong Xin SUN Yuan SUN Pin JIA Xiao Dong William W.Au MEI Can Hua XIA Zhao Lin Department of Occupation Health and Toxicology School of Public HealthFudan UniversityShanghai 200000China Department of Occupation Health Shanghai Municipal Health CommissionShanghai 200000China Shanghai Institute of Occupational Disease for Chemical Industry(Shanghai Institute of Occupational Safety&Health) Shanghai 200000China Division of Health Risk Factors Monitoring and Control Shanghai Municipal Center for Disease Control and PreventionShanghai 200000China University of Medicine PharmacyScience and TechnologyTargu MuresRomania and Shantou University Medical CollegeShantou 515000GuangdongChina

Objective This study was designed to conduct a retrospective and systematic occupational health risk assessment(OHRA)of enterprises that used benzene,toluene,and xylene(BTX)in Shanghai,China.Methods All data for the study were obtained from 1,705 occupational health examination and evaluation reports from 2013 to 2017,and a semiquantitative model following Chinese OHRA guidelines(GBZ/T 298-2017)was applied for the assessment.Results The selected enterprises using BTX were mainly involved in manufacturing of products.Using the exposure level method,health risk levels associated with exposure to BTX were classified as medium,negligible,or low.However,the risk levels associated with benzene and toluene were significantly different according to job types,with gluers and inkers exhibiting greater health risks.For the same job type,the health risk levels assessed using the comprehensive index method were higher than those using the exposure level method.Conclusion Our OHRA reveals that workers who are exposed to BTX still face excessive health risk.Additionally,the risk level varied depending on job categories and exposure to specific chemicals.Therefore,additional control measures recommended by OHRA guidelines are essential to reduce worker exposure levels.

关键词： Benzene Toluene xylene Occupational health risk assessment Exposure level method Comprehensive index method

Enhanced xylene sensing performance of hierarchical flower-like Co_(3)O_(4) via In doping

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Chinese Physics B 2023年第6期32卷 644-651页

作者：张京凌剑宇谷魁坤 Georgiy G.Levchenko 梁霄 State Key Laboratory of Superhard Materials Physics of CollegeJilin UniversityChangchun 130012China Institute for Interdisciplinary Biomass Functional Materials Studies Jilin Provincial Key Laboratory of Straw-Based Functional MaterialsJilin Engineering Normal UniversityChangchun 130052China Donetsk Institute for Physics and Engineering named after O.O.Galkin NAS of UkraineKyiv 03028Ukraine

Metal ions doping is a typical approach for tuning sensing properties of metal oxide semiconductors based gas sensors.Herein,hierarchical flower-like pure and In-doped Co_(3)O_(4) nanostructures assembled by porous two-dimensional(2D)nanosheets are synthesized via a solvothermal method and annealing process.The sensing measurements display that the In@Co_(3)O_(4)-4 based sensor possesses high response value of 55.9 toward 100 ppm xylene at 150 ℃,which is nearly 3.8times larger than that of pure Co_(3)O_(4) sensor.Furthermore,it possesses good selectivity and anti-humidity properties.Combined with the results of DFT calculations,the mechanism of enhanced gas sensing performance is analyzed systematically.

关键词： sensor Co_(3)O_(4) xylene density functional theory(DFT)

Design of Cr2O3@ZnO Hetero-junction Hierarchical Nanostructures with Enhanced xylene-sensing Properties

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Chemical Research in Chinese Universities 2018年第2期34卷 169-174页

作者： QIN Qixuan SHEN Zheng ZHANG Nan ZHANG Xindong State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 P. R. China

Cr2O3@ZnO hetero-junction hierarchical nanostructures were designed to be enhanced xylene sensing material, and thereinto, flower-like ZnO hierarchical nanostrnctures were synthesized via a solution-based method, and then Cr2O3 particles were developed on the surface of ZnO petals via a solvothermal method. From the results of XRD patterns, SEM and TEM images, it can be observed that ZnO has a high-quallity crystallinity and Cr2O3 particles scatter uniformly on the suruface of ZnO. The products with different ratios of Cr2O3 were used to fabricate gas sensors, and the result indicates that the hetero-junction structures prompt the response to xylene, and the reason may be attributed to the decrease of main carriers concentration caused by the p-n junction between ZnO（n-type semiconductor） and Cr2O3（p-type semiconductor）, as well as the catalytic oxidation effect on methyl groups of the xylene by Cr2O3.

关键词： ZnO Hetero-junction xylene

Photocatalytic oxidation of gaseous benzene,toluene and xylene under UV and visible irradiation over Mn-doped TiO_(2)nanoparticles

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Journal of Materiomics 2019年第1期5卷 56-65页

作者： Vassilios Binas Vassilis Stefanopoulos George Kiriakidis Panos Papagiannakopoulos Laboratory of Photochemistry and Kinetics Department of ChemistryUniversity of Crete71003HeraklionCreteGreece Institute of Electronic Structure and Laser(IESL) FORTHP.O.Box 1527Vasilika VoutonGR-71110HeraklionGreece Crete Center for Quantum Complexity and Nanotechnology Department of PhysicsUniversity of Crete71003HeraklionGreece

The photocatalytic oxidation of gaseous benzene,toluene and xylene(BTX)over un-doped,0.1 and 1 wt%Mn-TiO_(2)nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas.The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy.BTX underwent efficient decomposition over Mn-TiO_(2)photocatalysts under UV irradiation,more with oxygen presence and less without oxygen.More important toluene and xylene went substantial decomposition over 0.1 mol%Mn-TiO_(2)under visible irradiation with oxygen presence.The main final oxidation products in the UV photocatalysis of BTX were CO_(2),CO and H2O,with CO_(2) and CO yields 4 and 2 respectively.The conversion percentage of benzene,toluene,and xylene to CO_(2) were 63.6%,56.4%,51.8%,and to CO 29%,26.5%,23.2%,respectively.In the visible photocatalysis of toluene and xylene the yields of CO were insignificant.Formation of carbon containing deposits on TiO_(2)surfaces was observed after extensive UV photocatalysis of toluene and xylene,and such by-products surface coverage may reduce the photocatalytic activity of TiO_(2)samples.Some aspects of the photocatalytic mechanism were examined.

关键词： Mn-doped TiO_(2) Visible Light photocatalysis Photodegradation of benzene Toluene xylene Indoors air pollution

Synthesis, physicochemical characterizations and catalytic performance of Pd/carbon-zeolite and Pd/carbon-Ce02 nanocatalysts used for total oxidation of xylene at low temperatures

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Frontiers of Environmental Science & Engineering 2013年第3期7卷 365-381页

作者： Zeinab JAMALZADEH Chemical Engineering Faculty Sahand University of Technology Tabriz *** Iran Reactor and Catalysis Research Center (RCRC) Sahand University of Technology Tabriz *** Iran

In this work, xylene removal from waste gas streams was investigated via catalytic oxidation over Pd/ carbon-zeolite and Pd/carbon-CeO2 nanocatalysts. Acti- vated carbon was obtained from pine cone chemically activated using ZnC12 and modified by HaPO4. Natural zeolite of clinoptilolite was with HC1, while nano-ceria modified by acid treatment was synthesized via redox method. Mixed supports of carbon-zeolite and carbon- ceria were prepared and palladium was dispersed over them via impregnation method. The prepared samples were characterized by X-ray emission scanning electron diffraction （XRD）, field microscopy （FESEM）, Brunauer-Emmett-Teller surface area （BET）, Fourier transform infrared spectroscopy （FTIR） and thermogravi- metric （TG） techniques. Characterization of nanocatalysts revealed a good morphology with an average particle size in a nano range, and confirmed the formation ofnano-ceria with an average crystallite size below 60 nm. BET analysis indicated a considerable surface area for catalysts （-1000 m^2·g^-1）. FTIR patterns demonstrated that the surface groups of synthesized catalysts are in good agreement with the patterns of materials applied in catalyst synthesis. The performance of catalysts was assessed in a low-pressure catalytic oxidation pilot in the temperature range of 100℃-250℃. According to the reaction data, the synthesized catalysts have been shown to be so advantageous in the removal of volatile organic compounds （VOCs）, represent- ing high catalytic performance of 98% for the abatement of xylene at 250℃. Furthermore, a reaction network is proposed for catalytic oxidation of xylene over nanocata- lysts.

关键词： Pd/carbon-Ce02 Pd/carbon-zeolite pinecone ZnC12 catalytic oxidation xylene

Comparison of air-borne xylene biodegradation between immobilizedcell biofilter and biofilm attached biofilter

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Journal of Shanghai University(English Edition) 2007年第5期11卷 514-520页

作者：刘强刘学锦 AROWOLO E Babajide 安太成傅家谟盛国英 School of Environmental and Chemical Engineering Shanghai University Shanghai 200072 P. R. China State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 P. R. China

The Bacillus firmus was immobilized into Ca-alginate beads according to the different initial biomass concentration, calcification time and activation time. Three types of immobilized Bacillus firmus beads were packed respectively in trickling biofilter to purify xylene contained waste gases, and the performance of immobilized-cell biofilter was compared with traditional biofilm attached biofilter packed with two types of ceramic pellets. The results showed that three types of immobilized beads had different capabilities for removing xylene and life-spans. Higher initial biomass in immobilized beads resulted in better performance but shorter life-span. Activation process can remarkably enhance the activity of bacteria, and the removal efficiency of xylene can substantially be improved. Calcification time had influence on life-span of immobilized beads. Without acclimation, the cell-entrapped biofilter can obtain the maximum elimination capacity of 92.4 g/（m^3·h）. However, compared with biofilm attached biofilter, it has a poorer intrinsic drawback in volatile organic compounds （VOCs） removal due to the existence of excess mass transfer resistance.

关键词： immobilized-cell biofilter biofilm attached biofilter xylene biodegradation

Catalytic Elimination of Oxygenated Byproducts in the Toluene Methylation Process

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China Petroleum Processing & Petrochemical Technology 2023年第2期25卷 65-73页

作者： Hou Min Qi Xiaolan Zheng Junlin State Key Laboratory of Green Chemical Engineering and Industrial Catalysis SINOPEC Shanghai Research Institute of Petrochemical Technology Co.Ltd.Shanghai 201208China

Catalytic methylation of toluene with methanol is an important alternative pathway for xylene production.Previous studies have indicated that methanol always undergoes several side reactions on acidic zeolites,resulting in oxygencontaining byproducts such as dimethyl ethers,ketones,and carboxylic acids.Herein,the presence and distribution of the oxygenated compounds formed during toluene methylation were firstly examined by systematic chromatographic analysis.Plausible formation mechanisms for the various oxygenates are discussed.The most problematic byproduct is found to be acetic acid,which can lead to inferior product quality and damage downstream units.A feasible solution is presented for oxygenate removal after toluene methylation,in which acetic acid is eliminated by catalytic decomposition into low-boilingpoint acetone over a MgO catalyst.This process allows for all of the low-boiling-point oxygenates,including methanol,dimethyl ether,acetone,and butanone,to be removed from the aromatics phase,taking advantage of the temperature of the reaction effluent and standard distillation equipment.X-ray diffraction was used to characterize the crystal phase of the fresh and used MgO decarbonylation catalysts,while thermogravimetry/mass spectrometry and Fourier-transform infrared spectroscopy were applied to investigate the transformation mechanism of acetic acid over the decarbonylation catalyst.CO insertion and ketonization of acetic acid accounted for the formation and elimination of acetic acid,respectively.The combined methylation/decarbonylation process should enable the production of high-quality xylenes,an important industrial feedstock,by overcoming the main technical obstacles associated with the toluene methylation process.

关键词： xylene catalytic methylation decarbonylation toluene MgO catalyst

Selective Hydrogenation of Polycyclic Aromatics to Monocyclic Aromatics over NiMoC/HβCatalysts in a Methane and Hydrogen Environment

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China Petroleum Processing & Petrochemical Technology 2023年第2期25卷 92-100页

作者： Shen Zhibing Fu Rao Zhang Shangli Wang Shunmei Zhang Wu Tang Ruiyuan Liang Shengrong Zhang Juntao Yuan Shibao Jiang Haiyan Xi’an Key Laboratory of Low-carbon Utilization for High-carbon Resources College of Chemistry and Chemical EngineeringXi’an Shiyou UniversityXi’anShaanxi 710065China Shaanxi Engineering Research Center of Green Low-carbon Energy Materials and Processes Xi’an Shiyou UniversityXi’anShaanxi 710065China College of Petroleum Engineering Xi’an Shiyou UniversityXi’anShaanxi 710065China

To obtain high yields of monocyclic aromatic hydrocarbons with methyl side chains,such as toluene and xylene,methane(CH_(4))can be introduced into the hydrocracking of polycyclic aromatic hydrocarbons.CH_(4)can participate in the reaction,supply methyl side chains to the product,and improve product distribution.In this study,the hydrogenation reaction of polycyclic aromatic hydrocarbons over a carbonized NiMo/Hβcatalyst in a CH_(4)and hydrogen(H_(2))environment was investigated to study the promotional effect of CH_(4)on the hydrocracking of polycyclic aromatics.Under conditions of 3.5 MPa,380℃,volume air velocity of 4 h^(-1),gas-oil volume ratio of 800,and H_(2):CH_(4)molar ratio of 1:1,the conversion rate of naphthalene was 99.97%,the liquid phase yield was 93.62%,and the selectivity of BTX were 17.76%,25.17%,and 20.47%,respectively.In comparison to the use of a H_(2)atmosphere,the selectivity of benzene was significantly decreased,whereas the selectivity of toluene and xylene were increased.It was shown that CH_(4)can participate in the hydrocracking of naphthalene and improve the selectivity of toluene and xylene in the liquid product.The carbonized NiMo/Hβcatalyst was characterized by a range of analytical methods(such as X-ray diffraction(XRD),ammonia-temperature-programmed desorption(NH3-TPD),hydrogen-temperature-programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)).The results indicated that Ni and Mo carbides were the major species in the carbonized NiMo/Hβcatalyst and were considered to be active sites for the activation of CH_(4)and H_(2).After loading the metal components,the catalyst displayed prominent weak acidic sites,which may be suitable locations for cracking,alkylation,and other related reactions.Therefore,the carbonized NiMo/Hβcatalyst displayed multiple functions during the hydrocracking of polycyclic aromatic hydrocarbons in a CH_(4)and H_(2)environment.These results could be used to develop a new way to efficiently utilize polycyclic aromatic hydrocarbons and natural g

关键词： methane polycyclic aromatic hydrocarbons hydrocracking NiMoC/Hβ toluene xylene