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
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
He Han,Anfeng Zhang,Limin Ren,Xiaowa Nie,Min Liu,Yi Liu,Chuan Shi,Hong Yang,Chunshan Song,Xinwen Guo
Shape-selective alkylation of toluene with methanol is one of the most attractive promising synthetic routes to para -xylene. To date, modified ZSM-5 zeolites are considered to be one of the best candidate catalysts for this reaction. Although the para -selectivity could be tuned to approaching 100% by modification of the zeolite and optimization of reaction conditions, at present, there is still a lack of effective means to inhibit the rapid deactivation of the catalysts due to coke formation. In this work, a coke-resistant (Pt + Ni)/ZSM-5 zeolite with excellent stability for shape-selective alkylation of toluene with methanol to para -xylene is developed. The pore structure and acid properties of the zeolite are effectively tuned to ensure high para -selectivity. Meanwhile, the co-existence of Pt and Ni species in this catalyst plays the critical role in inhibiting coke formation, as the two species concurrently impede the formation of olefins, the main coking precursors, via two distinctive mechanisms.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xiao Zhao,Xuan Shi,Zhongshun Chen,Long Xu,Chengyi Dai,Yazhou Zhang,Xinwen Guo,Dongyuan Yang,Xiaoxun Ma
A series of ZnO-ZrO 2 solid solutions with different Zn contents were synthesized by the urea co-precipitation method, which were coupled with H-ZSM-5 zeolite to form bifunctional catalysts. As a new benzene alkylation reagent, syngas was used instead of methanol to realize the efficient conversion of syngas and benzene into toluene and xylene. A suitable ratio of ZnO-ZrO 2 led to the significant improvement in the catalytic performance, and a suitable amount of acid helped to increase the selectivity of toluene/xylene and reduce the selectivity of the by-products ethylbenzene and C 9 + aromatics. The highest benzene conversion of 89.2% and toluene/xylene selectivity of 88.7% were achieved over 10% ZnO-ZrO 2 &H-ZSM-5 (Si/Al = 23) at a pressure of 3 MPa and a temperature of 450 °C. In addition, the effect of the zeolite framework structure on product distribution was examined. Similar to the molecular dynamics of aromatic hydrocarbons , H-ZSM-5 zeolites comprise 10-membered-ring pores, which are beneficial to the activation of benzene; hence, the conversion of benzene is higher. H-ZSM-35 and H-MOR zeolites exhibited small eight-membered-ring channels, which were not conducive to the passage of benzene; hence, the by-product ethylbenzene exhibits a higher selectivity. The distance between the active centers of the bifunctional catalysts was the main factor affecting the catalytic performance, and the powder mixing method was more conducive to the conversion of syngas and benzene.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2024
·
IF 4.4
Renjie Deng,Huajie Liu,Haishuai Cui,Yao Tian,Hai Yang
In this work, we have developed a green method for the preparation of para-nitrotoluene through the catalytic nitration of toluene with nitrogen dioxide (NO2) under the promotion of dioxygen (O2). The experimental results reveal that the dealumination of Hβ zeolite has a significant effect on the catalysis of the developed NO2–O2–acetic anhydride (Ac2O) system, in which the conversion of toluene is 78.1% and the selectivity to para-nitrotoluene is 71.8%. Furthermore, the nature of different dealuminated catalysts was investigated by nitrogen adsorption–desorption analysis, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), thermal gravimetric analysis (TGA), inductively coupled plasma (ICP), ammonia temperature-programmed desorption (NH3-TPD), pyridine adsorbed Fourier-transform infrared (Py-FT-IR), scanning electron microscopy (SEM) and 27Al magic-angle spinning nuclear magnetic resonance (27Al MAS NMR) techniques. The results of characterization indicate that the structure of the Hβ zeolite still remains and that of Al species in the extra-framework is preferentially removed after acid treatment. Based on the combined results of catalytic characterization and DFT calculation, a feasible reaction mechanism of improved para-selectivity in toluene nitration was suggested for the NO2–O2–Ac2O system.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2016
·Vol. 6
·期 8
·2647-2652
·
IF 5.287
Hualei Hu,Jinghui Lyu,Jiayao Rui,Jie Cen,Qunfeng Zhang,Qingtao Wang,Wenwen Han,Xiaonian Li
Ethylbenzene is the major side product in benzene alkylation with methanol and it is difficult to be suppressed over hierarchical porous ZSM-5. Moreover, the separation of ethylbenzene from xylene still remains a great challenge. Our research indicated that ethylbenzene formation could be highly suppressed by changing the Si/Al ratio of the catalyst. Hierarchical porous ZSM-5 catalysts with different Si/Al ratios were prepared via reducing the amount of Al in the solvent evaporation assisted dry gel conversion method. In this method, tetra-n-propylammonium hydroxide was used as the direct agent to create micropores, and hexadecyltrimethoxysilane was added to create additional porosities by forming organic assemblies which occupied a certain space between zeolitic walls. The catalyst with a Si/Al ratio of 1800 could achieve high benzene conversion (59.5%) and high xylene selectivity (39.0%) as well as excellent suppression of ethylbenzene formation (<0.1%).
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Guoqiang Hou,Tingjun Fu,Xin Li,Qian Ma,Zhong Li
HZSM-5 catalysts with abundant silanol nests were fabricated by removing framework Al, which effectively promoted the selective alkylation of toluene with methanol by inhibiting the deep alkylation of aromatics to heavy aromatics and the conversion of methanol to light hydrocarbons. Correspondingly, the alkylation efficiency reached 65.3% at a toluene conversion of 31.3% over dealuminated HZSM-5, higher than the 55.2% efficiency and 28.0% conversion of parent zeolites, respectively. In situ DRIFTS and single-factor experimental clarified that toluene adsorption was enhanced and methanol to hydrocarbons was inhibited with the presence of silanol nests. Additionally, by increasing the crystal size of HZSM-5 with silanol nests from 2 to 5 µm, para-xylene selectivity was increased from 36.1% to 65.5% because of the enhanced diffusion barrier . The finding of the positive effect of the silanol nests on toluene alkylation can provide a solid fundamental basis for the rational design of catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Asia-Pacific Journal of Chemical Engineering
·
2021
·Vol. 16
·期 3
·e2609
·
IF 1.447
Siliang Gao,Wencheng Tang,Ming Zhao,Siyuan Qie,Weiwei Pang,Longsheng Tian
Highly efficient separation of benzene, toluene, and xylenes (BTXs) from pyrolysis gasoline is very important in petrochemical industries. Though the extractive distillation (ED) process is simpler and consumes less energy compared with liquid–liquid extraction process, it is difficult for a single solvent, for example, sulfolane, to achieve both high purity and high yield of BTXs. In this work, methylsulfonylethane (MSE) was chosen as a cosolvent to improve the selectivity of sulfolane after solvent screening, and factors that may affect the selectivity of the composite solvent were fully investigated, such as the content of cosolvent, solvent to feed ratio, the composition of the feed, and temperature. Furthermore, 240 h of continuous extractive distillation and solvent recovery experiment was carried out using sulfolane (85 wt%)–MES (15 wt%) mixture as solvent. The purity of mixed aromatics obtained was 99.83%, and the yield was as high as 99.7%.
研究领域:
化学工程
·
石油化工
✓ 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
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 4
·1614-1626
·
IF 3.442
Pan Liuyi,He Yulong,Niu Menglong,Dan Yong,Li Wenhong
Ni 2 P catalysts supported on different supports, such as SiO 2 from different sources, Al 2 O 3 , TiO 2 and ZrO 2 were prepared for the hydrodeoxygenation of p-cresol (monocyclic phenol model in coal tar). The reaction was carried out on a fixed-bed reactor at a temperature of 330–390 °C under 2 MPa. The order of conversion of p-cresol was as follows: Ni 2 P/SiO 2 -2 > Ni 2 P/SiO 2 -3 > Ni 2 P/SiO 2 -1 > Ni 2 P/Al 2 O 3 > Ni 2 P/ZrO 2 > Ni 2 P/TiO 2 . Ni 2 P/SiO 2 -3 shown higher DDO path selectivity, resulting in the conversion of p-cresol of 93% and a selectivity of 72.6% for BTX products under the reaction temperature of 370 °C with LHSV of 0.5 h −1 . This catalyst was also used for the hydrodeoxygenation of the crude phenolic mixture extracted from coal tar, which shown that the phenol deoxidation rate was 87.6% and the BTX product selectivity was 73.7% by GC–MS.
研究领域:
化学工程
·
催化反应
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Shu-Huan Chen,Huma Javeria,Xu-Hui Sun,Zhen-Xia Du
With the proliferation of vehicles in households, people are spending more and more time in their cars, so it is important to ensure the air quality and safety of the car. In this research, environmentally friendly, green PET@PDA@MIL-101(Fe) (PPM) was prepared by in-situ solvothermal growth and acid etching methods, which was categorized by SEM, FTIR, XRD, XPS, and BET. PPM was used to adsorb benzene, toluene, and m-xylene at low concentrations. The maximum amount of adsorption of PET@PDA@MIL-101(Fe) (PPM) for benzene, toluene, and m-xylene was 68.72 mg/g, 91.63 mg/g, and 78.47 mg/g respectively. The adsorption process of PPM is well fitted by the pseudo-first-order kinetic model and Langmuir isothermal adsorption model. Furthermore, PPM exhibited excellent toluene removal performance in simulated vehicles and excellent cycling capability in adsorption-desorption experiments. As a result, PPM can be used to treat and manage toluene volatile organic compounds (VOCs) at low concentrations.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Environmental Technology & Innovation
·
2020
·
IF 3.356
Chao Zhu,Zarak Mahmood,Abdul Saboor Arshad,Jia Liu,Hongrui Ma
Wastewater treatment has become a major global issue due of undegradable pollutants. As toxic water pollutants , namely o-toluidine and p-toluidine are difficult to treat, this study uses the silicon rubber technology to treat them. A pair of modules having single tabular nonporous silicon rubber tube and HCl stripping solution were set up to extract o-toluidine and p-toluidine from high-saline wastewater. Reaction quotient ( Q C ) was calculated after every 12 h intervals to evaluate the equilibrium reaction. The effect of concentration, pH, temperature, ionic strength, and flow rate on the permeability (P) and removal efficiency ( η ) were investigated to illustrate the process parameters and mechanisms of recovery of both elements from wastewater. The results showed that the recovery efficiency was more than 96% with concentration of 2–10g/L. When pH of the extraction solution was 2 or less, the pollutant permeability efficiency was nearly 95%. Moreover, when the salting strength was over 10%, the recovery efficiency increased quickly to some extent. Permeability, which mainly influenced by membrane resistance and desorption rate, initially increased and then decreased when the water flow increased from 2 and 20 mL/min. Aging of silicon rubber tube was also studied with respect to salinity , temperature, and acidity. Acidity and temperature was found to have a significant effect on the tube, permeability increased with an increase in aging, and aging had a minor effect on the elastic properties of the silicon rubber tube. Absorption and diffusion of water in silicon rubber tubes decreased when salinity increased more than 10%, which increased separation of p-toluidine and water. Due to this, there is no need of desalination before membrane extraction in treatment of p-toluidine wastewater with high saline. Thus, this study demonstrates that membrane extraction is a highly energy-efficient process for the effective recovery of o-toluidine and p-toluidine from wastewater with high salinity.
研究领域:
环境科学
·
化学工程
✓ 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）