FLUID PHASE EQUILIBRIA
·
2021
·
IF 2.775
Zhenxing Cai,Hui Zhao,Xin Zhou,Xiaobo Chen,Chaohe Yang
Solid-liquid equilibria of three binary mixtures consisting of para-xylene, ortho-xylene, meta-xylene and ethylbenzene were investigated in this study using differential scanning calorimetry (DSC) method, the mixtures were cooled to -120 °C and then heated to 20 °C at different heating rates, eutectic phase diagrams were observed for para-xylene/ortho-xylene and para-xylene/meta-xylene binary systems. The freezing point of pure ethylbenzene at atmospheric pressure is around -95 °C, but due to the effect of induction time, the observed freezing temperature is lower than -120 °C, the operation temperature of industrial xylene crystallization separation process is higher than -80 °C traditionally, therefore ethylbenzene will not crystallize in practical process, the phase diagram for para-xylene/ethylbenzene was not achieved. The experimental data were compared with data from other literatures and new features were found. The data were well correlated by Apelblat equation and λ H equation, it is significative to provide important engineering data for the separation and purification of xylene mixtures.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2015
·
IF 2.679
Xianyang Meng,Xiaoyun Gu,Jiangtao Wu,Velisa Vesovic
The compressed liquid viscosities of ortho -xylene, meta -xylene, para -xylene and ethylbenzene were measured using a vibrating-wire viscometer at different temperatures and pressures. The measurements were performed over the temperature ranges of (273 to 373) K for o -xylene and m -xylene, (293 to 373) K for p -xylene and (253 to 373) K for ethylbenzene, at pressures from (0.1 to 30) MPa, except for ethylbenzene for which the pressure range was up to 35 MPa. The combined expanded uncertainty of the reported viscosity is better than 2% with a confidence level of 0.95 ( k = 2). The experimental data were correlated with the empirical Andrade–Tait equation which reproduced the results with the average absolute percentage deviations of (0.25, 0.15, 0.16 and 0.23)% for o -xylene, m -xylene, p -xylene and ethylbenzene, respectively. The present results are in good agreement with most of the literature values.
研究领域:
化学工程
·
物理化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2023
·
IF 3.8
Wenwen Zhang,Zhigang Xue,Liyun Cui,Haoliang Gao,Di Zhao,Rongfei Zhou,Weihong Xing
The synthesis of a continuous IMF zeolite membrane was fabricated on tubular substrates by seeded growth for the first time. The straight channels of IMF zeolite with diameters of 0.53–0.59 nm are distinguishable for p -xylene from o -xylene molecules. Pure IMF-phase high-silica IM-5 zeolite seeds with uniform and fine crystal size were fabricated by a new sonication-assisted aging process. The seeds were coated on the support by dipcoating and induced the formation of continuous membrane. Separation performance in p -/ o -xylene mixture was investigated at various temperature and pressure. The typical IM-5 zeolite membrane had p -/ o -xylene separation factor of 3.7. Our results suggest that IM-5 zeolite is a potentially good membrane material for the separation of xylene mixtures.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Chemical Engineering and Processing-Process Intensification
·
2017
·
IF 2.234
Haofan Yang,Yufeng Hu
The separation of para -xylene ( p -xylene) from its mixtures with meta -xylene ( m -xylene) using aqueous hydroxypropyl- β -cyclodextrin (HP- β -CD) solution by a two-step liquid–liquid extraction process has been experimentally investigated. The results show that HP- β -CD can form inclusion complexes of different strengthes with p -xylene and m -xylene. It is shown that the different strengthes stem from the differences in size, relative alkalinity and dipole moment between the two xylene isomers. The optimum separation condition has been determined as follows: the concentrations of HP- β -CD and initial xylene mixture are 0.1448 g (g H 2 O) −1 and 0.4 g (g H 2 O) −1 , respectively. Under this condition, the separation factor α, which is the most important evaluation index in extraction process, is 1.469. The ratio of the formation constants, K PX / K MX , has been determined to be slightly greater than α, consistent with the theoretical prediction. Moreover, a new method for calculation of α has been developed. The experimental results demonstrate the almost perfect reusability of aqueous HP- β -CD solution. For the experiment that begins with a 1:1 mixture of p -xylene and m -xylene, the p -xylene concentration in the extraction phase is 59.71 wt%. After repeating the extraction process 4 times, the concentration of p -xylene in the extraction phase can reach 81.48 wt%.
研究领域:
化学工程
·
分离科学
✓ 已验证
产品关联
DOI
高影响因子
WATER AIR AND SOIL POLLUTION
·
2022
·Vol. 233
·期 5
·1-13
·
IF 2.984
Chen Yuan,Zhang Tong,Luo Shuai,Zhang Yurong,Liu Yuanyuan
Xylene is a typical petrochemical industry pollutant. The fate of xylene spilled into soil was investigated in laboratory-scale batch and column experiments. The results show that free xylene in the soil evaporated quickly (7.2–10.4 mg h −1 ), but any fraction adsorbed onto the soil particles evaporated much more slowly (2.3–2.4 mg h −1 ). The retention of xylene in the soil was mainly controlled by its adsorption onto the soil minerals. The adsorption was best described using a pseudo-second-order kinetic model and Langmuir model. Adsorption up to 530 mg kg −1 was observed, and minerals such as quartz and kaolinite were the key adsorbents. Adsorption of xylene was promoted by the presence of dissolved organics up to about 50 mg L −1 , but it was significantly inhibited by cobalt-bearing compounds which are often used as catalysts in the petrochemical industry. The release of xylene from soil would be facilitated by intense rainfall and cobalt-bearing compounds but would be inhibited with the increase of rainwater acidity. This study reveals the environmental behavior of xylene in soil and provides scientific guidance for pollution control and risk assessment of BTEX contaminated sites.
研究领域:
环境科学
·
污染生态学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Gankai Huang,Xinyi Huang,Junlin Huang,Xuye Hou,Youquan Zhang,Fang Lai,Ronghui Lin,Kangquan He,Qunhua Long,Hongbing Ji,Kungang Chai
Efficient purification of xylene isomers, particularly the separation of para- / meta -xylenes (PX/MX), is industrially crucial but challenging. Here, we report a classical aluminum-based metal–organic framework (MIL-160) that exhibits an exceptional meta-selectivity in liquid-phase competitive adsorption of xylene isomers. The outstanding separation performance of MIL-160 for xylene isomers is confirmed by dynamic breakthrough experiments. The PX eluted first and breakthrough of MX didn’t occur until a long retention times, which is in accordance with the results observed from static adsorption experiment. Molecular simulations and calculations suggested that the largest affinity of MIL-160 toward MX, potentially due to the good fitness between the 1D square-shaped channel and MX. To improve the productivity of purified PX in continuous separation mode, we speculated that combining the MX-selective property of MIL-160 and the previously reported ortho -xylene (OX)-selective property of CAU-23 can enhance the separation effect between PX and the other two isomers. So, MIL-160 and CAU-23 were filled simultaneously in column and the effect of mass ratio of them on PX productivity was investigated. The results indicated that when the mass ratio of MIL-160 versus CAU-23 was 4:6, MX and OX almost simultaneously eluted and reached saturation, which can maximize the productivity of PX. This study offers a feasible strategy for isolating PX from xylene isomer with low energy consumption and high efficiency.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMIE INGENIEUR TECHNIK
·
2021
·
IF 1.672
Hao Guo,Zheng Wan,Yanhong Li,Xiao He,Aisheng Huang
In this study, a graphene oxide (GO) membrane is developed for the separation of p -xylene (PX, 0.58 nm) from o -xylene (OX, 0.68 nm). Attributing to the suitable d-spacing size (0.58 nm), the GO membrane allows more PX to pass through than OX, leading to a high PX/OX selectivity. At 110 °C for the separation of equimolar PX/OX mixture, the PX/OX separation factor is 9.4 and PX flux is 145.3 g m −2 h −1 , respectively, which is promising for the separation of xylene isomers by pervaporation. The separation performance of the GO membrane is further confirmed by simulation studies.
研究领域:
材料科学
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化学工程
·
分离技术
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2021
·
IF 8.271
Liping Yang,Jiacheng Xing,Danhua Yuan,Lin Li,Yunpeng Xu,Zhongmin Liu
MIL-125 is a metal-organic framework with great potential for the adsorption and separation of xylene isomers. However, MIL-125 is usually synthesized under anhydrous and anaerobic conditions. In this study, homogeneously shaped and highly crystalline MIL-125 was synthesized by introducing water-resistant titanium-containing oligomers into the synthesis process. With the assistance of the novel oligomers, MIL-125 can be synthesized in the presence of water, which meets batch-production requirements. The adsorption separation performance of the obtained highly crystalline MIL-125 was also significantly enhanced. The para- xylene/ meta- xylene selectivity can reach 13.5 in mesitylene, which is higher than the selectivity values of most previously reported para -selective adsorbents. The MIL-125 xylene separation performance was verified using both batch adsorption and breakthrough experiments in the liquid phase. In addition, the influence of the solvent effect was evaluated through microcalorimetric experiments, liquid-phase adsorption experiments, and theoretical calculations.
研究领域:
材料科学
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化学工程
·
吸附技术
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2013
·Vol. 5
·期 6
·1517-1523
·
IF 5.181
Yan Liu,Xiaozhao Zhou,Xinmei Pang,Yinying Jin,Xiangju Meng,Xiaoming Zheng,Xionghou Gao,Feng-Shou Xiao
Graphical Join the chain gang: Chain-like ZSM-5 crystals that are synthesized in the presence of starch show higher p -xylene selectivity in m -xylene isomerization than normal, mesoporous, and sheet-like ZSM-5 crystals. ZSM-5 zeolite crystals with controllable b- axis length (sheet-like, S-ZSM-5; chain-like, C-ZSM-5) have been synthesized by using urea and starch as additives in the starting aluminosilicate gels. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images show that these zeolite samples have good crystallinity. Transmission electron microscopy (TEM) images show that there is a strong chemical interaction between the stacked crystals in C-ZSM-5 samples. N 2 sorption isotherms indicate that C-ZSM-5 crystals are mesoporous. Catalytic tests for the formation of p -xylene from m- xylene isomerization show that, compared with other zeolite catalysts, C-ZSM-5 catalysts give both high conversion and improved p -xylene selectivity, which are attributed to the combination of relatively long b -axis length and the present mesoporosity in the crystals. The improvement of p -xylene selectivity in catalytic m- xylene isomerisation is of great importance for selective industrial production of p -xylene in the future.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Wei Chen,Pengfei Wang,Weike Jia,Huidan Zeng
Improving the zeolite adsorption separation efficiency of individual xylene isomer with high purity from their mixture is still a pressing challenge in the fine chemical industry. Herein, plate-like silicalite-1 (p-S-1) zeolite crystals with short b-axis thickness have been successfully synthesized by combination of tributylphosphine oxide (TBPO) modifier and F − -assisted crystallization method to first investigate the separation property of xylene isomers. The morphology and structure of the p-S-1 zeolite crystals were characterized by XRD, FTIR, BET, SEM and TEM. The results showed that the p-S-1 zeolite crystals with thickness of about 50 nm along the b-axis and high crystallinity, as well as extremely rich micropores, were obtained by crystallizing the gels with TBPO/SiO 2 ≥ 0.04. By static adsorption experiment and fixed bed experiment, xylene isomers selective adsorption separation property of the p-S-1 zeolite crystals prepared at TBPO/SiO 2 = 0.04 was investigated. The static adsorption experiment demonstrated that the p-S-1 zeolite crystals exhibited higher adsorption capacity of p-xylene (p-X) and more excellent xylene isomers separation performance than that of the bulk coffin-shaped silicalite-1 (c-S-1) zeolite crystals because of the shorter mass transfer channel and larger diffusivity differences between p-X and o-X/m-X/EB. The dynamic adsorption experiment in simulated five-component solutions diluted by isooctane (IO) indicated that the p-S-1 zeolite crystals had excellent xylene isomers selective adsorption separation performance. The optimum dynamic xylene isomers selective adsorption separation factors for p-X/o-X, p-X/m-X and p-X/EB were 25.41, 36.45 and 11.57 at 150 °C, respectively. The regeneration experiment also indicated that the p-S-1 zeolite crystals had more stable structure and longer lifetime. This work suggested that the p-S-1 zeolite crystals had great potential as new adsorbent for selective adsorption separation of xylene isomers.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Weilin Qi,Xuejiao Wang,Zeyu Liu,Kaerdun Liu,Yifan Long,Wanwan Zhi,Cheng Ma,Yun Yan,Jianbin Huang
Hypothesis Distinguishing substituted aromatic isomers is a challenging task because of the great similarity of their physicochemical properties. Considering xylene isomers have drastically different geometrical shapes, we predict this would show great impact on the self-assembling behavior of various xylene isomer@cyclodextrin inclusion complex. Experiments Through host–guest crystalline self-assembly, among three isomers, only ortho -xylene is capable to form hydrogels with α-cyclodextrin. ROESY NMR, molecular simulations and circular dichroism spectra suggest that the ortho selectivity comes from the difference in the conformation of host–guest building block. The larger volume, and steric hinderance of the ortho isomer make it most possibly decrease their tendency to adopt more mobile orientations in cyclodextrin-based complex as meta and para isomers do, resulting in gel formation. Findings Herein, we report a novel, facile and environmentally-friendly protocol on the recognition of ortho benzene isomers using α-cyclodextrin through host–guest crystalline self-assembly. Visual recognition of ortho -xylene is achieved through amplifying the structural difference of xylene isomers at molecular scale into macroscopic scale. We believe this work unveils subtle rules to control macroscopic assemblies at the molecular level and highlights the potential of using macrocyclic compounds to improve the quality and reduce the energy bill for separation in petrochemical industry.
研究领域:
化学
·
材料科学
·
分析化学
·
物理化学
·
石化工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FLUID PHASE EQUILIBRIA
·
2017
·
IF 2.473
Kai Kang,Xiaopo Wang
The experimental measurements for liquid densities of n -decane and p -xylene binary mixtures were performed over the entire composition with a high-pressure vibrating-tube densimeter. The temperature ranges for the present measurement were from 293.15 K to 363.15 K and the pressures were reached to 60 MPa. The experimental uncertainty is estimated to be 0.001 with 0.95 confidence level. Experimental density values were fitted by the modified Tammann–Tait equation. The PC-SAFT equation of state and Cibulka's equation was used to predict the densities of n -decane and p -xylene and its mixtures. In addition, derived volumetric properties, such as the excess molar volumes , the isothermal compressibility , and isobaric thermal expansivity, were calculated from the experimental density data. The effects of pressure and temperature on the derived properties were also discussed.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）