PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2024
·
IF 6.9
Pengkang Zhang,Tao Pan,Lijuan Ma,Bangguo Liu,Shuang Tian,Xiurong Chen
Foam stability plays an important role in the effect of blocking the odorous substances. Based on the characteristic of xanthan gum of enhancing foam stability and preventing foam from water drainage and coarsening, this paper investigated the half-life, foaming volume, viscosity, drainage curve, and bubble microstructure of foam filled with 0.1%, 0.2%, and 0.3% xanthan gum respectively, and further analyzed the correlation between xanthan gum dosage, viscosity of foam solution and foam stability. The effect of different stability foams on para-xylene was tested. The results showed that compared with no xanthan gum, the half-life of foam with 3% xanthan gum was extended from 1 to 61 h, the drainage time increased from 4.5 to 85 h, and the foaming coarsening rate slowed down 3 times. The addition of 0.3% xanthan gum reduced the peak value of the p-xylene dispersion by 83.7% and postponed the peak time by 6 times.
研究领域:
环境科学
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化学工程
·
材料科学
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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
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材料科学
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产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2023
·Vol. 25
·期 17
·2582-2590
·
IF 3.1
Zhenxing Cai,Hui Zhao,Jixiang Liu,Xiaobo Chen,Chaohe Yang
A crystallization separation technique for xylene purification was proposed, which is a multi-stage process that is operated under three-phase (solid, liquid, and gas) coexisting conditions with decreasing temperatures and pressures. In contrast to conventional crystallization processes, centrifugation, filtration, and washing steps are not required. The proposed technique also differs from batch stripping crystallization, insomuch as para-xylene is recovered as much as possible via purifying the vapor fraction further and keeping the operating conditions close to the eutectic point. A series of models were developed to describe the ternary phase equilibrium and the mass and heat balances. Then, binary parameters between xylene isomers were fitted from experimental data, and a flowchart was proposed featuring the means to determine the phase compositions and flowrates. These were subsequently validated by experiments. This contributed to developing a practical multi-stage process that, when applied to a practical xylene mixture, resulted in a yield of more than 80% and purity in excess of 99.5%.
研究领域:
化学工程
·
材料科学
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产品关联
DOI
高影响因子
WATER AIR AND SOIL POLLUTION
·
2023
·Vol. 234
·期 4
·1-13
·
IF 2.9
Ma Lijuan,Linghu Shanshan,Chen Zhichong,Wang Shuoyuan,Gu Hao,Pan Tao,Chen Xiurong
The diffusion of odour caused by excavation disturbance during the restoration of pesticide sites adversely affects the surrounding environment. Therefore, it is essential to develop a new type of odour inhibitor that has both adsorption and oxidation functions and can effectively block odour. In this study, bentonite-modified cetyltrimethyl ammonium bromide (CTAB) was synthesised, and the structural changes of bentonite before and after modification were analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and other characterisation methods. Urea peroxide was loaded on modified bentonite (150C-Bent) by in situ synthesis method, and the preparation conditions were optimised. The effects of temperature, humidity and species on the adsorption behaviour and adsorption kinetics were studied by adsorption experiments. It is demonstrated that CTAB is embedded in bentonite through ion exchange, and the interlayer spacing expands from 1.42 to 3.11 nm. The optimal loading mass ratio of modified bentonite to urea peroxide was 1:1.5 and pH was 3. When the relative humidity is 54.3% and the temperature is 55 °C, the removal effect of paraxylene is the best; the optimal removal reached 82.4%. The adsorption behaviour of 1.5UHP-Bent conforms to the pseudo-second-order kinetic adsorption model. The adsorption pathway of paraxylene on UHP-Bent mainly includes partition effect and hydroxyl radical capture.
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2024
·
IF 5.8
Yuwen Deng,Wenhao Yuan,Sandro Gaïl,Wei Li,Long Zhao,Jiuzhong Yang,Fei Qi,Yuyang Li,Philippe Dagaut
Pyrolysis and oxidation of p -xylene over wide conditions were studied in this work in order to provide a comprehensive insight into the combustion chemistry of p -xylene. Concerning this goal, the pyrolysis of p -xylene was investigated in a flow reactor at pressures from 0.04 to 1 atm over the temperature range of 1000–1600 K. Key radicals, isomers and PAH products including three xylyl isomers, benzyl, xylylene isomers, styrene, benzene, fulvene, indene, naphthalene and phenanthrene, were identified and quantified using synchrotron vacuum ultraviolet photoionization mass spectrometry. The oxidation of p -xylene was studied in a jet-stirred reactor at 10 atm, 800–1300 K and equivalence ratios of 0.5–2.0 with a residence time of 0.5 s. Oxidation products were quantified by using gas chromatography combined with mass spectrometry and Fourier transform infrared spectrometry. A kinetic model for p -xylene combustion over wide conditions was developed based on our previously proposed p -xylene oxidation model and validated against the new experimental measurements in this work and literature reported experimental data, including flow reactor oxidation, laminar premixed flame, ignition delay time and laminar burning velocity. In the flow reactor pyrolysis, p -xylene mainly undergoes unimolecular decomposition to yield p -xylyl, which mainly suffers the H-loss reaction to form p -xylylene and isomerization reaction to form o -xylyl. The resonantly stabilized fulvenallenyl and benzyl radicals play an important role in the formation of bicyclic and tricyclic PAHs including indene, naphthalene, and phenanthrene. In the JSR oxidation, p -xylene is predominantly consumed via H-abstraction by oxygenated radicals such as OH, O, and HO 2 forming p -xylyl, which can be oxidized by HO 2 and eventually converted to p -methylbenzaldehyde. As the most abundantly produced oxygenated aromatics, further consumption of p -methylbenzaldehyde results in the formation of other observed oxygenated aromatics such as cresol, benzofuran, and benzaldehyde. The combustion chemistry of three C 8 H 10 isomers, i.e., p -xylene, o -xylene, and ethylbenzene, were also compared in terms of pyrolysis and oxidation fuel reactivity, and PAHs formation and growth, showing remarkable fuel isomeric effects.
研究领域:
化学工程
·
燃烧科学
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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
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Chengming Wu,Quan Wang,Jifan Li,Chun-Ling Liu,Wen-Sheng Dong
Catalytic conversion of biomass-derived platform chemicals into bulk chemicals p -xylene (PX) is appealing yet challenging due to low catalytic efficiency and severe reaction conditions. In this work, we fabricated a series of phosphate-modified ZrO 2 /SBA-15 ( x P-Zr/SBA-15) via adjusting the addition of phosphoric acid, and used them for the catalytic conversion biomass-derived 2,5-dimethylfuran (DMF) and ethylene to PX. Because of the enhanced adsorption capability for the reactant molecules (DMF and ethylene) and the good synergistic effect between Brønsted acid sites (P-OH) and Lewis acid sites (Zr 4+ ), 30P-Zr/SBA-15 revealed an excellent catalytic performance in the selective conversion of DMF into PX. The DMF conversion was 98.5%, PX yield was 92.0% at 250 °C for 12 h, and the corresponding PX productivity was upto 50.5 mmol PX ·g cat −1 ·h −1 . The results are far superior to those obtained on most previously reported catalysts in the literature under similar reaction conditions. The kinetic study revealed that 30P-Zr/SBA-15 has a lower apparent activation energy for the tandem reaction including the Diels-Alder reaction (57.0 kJ·mo −1 ) and dehydration reaction (37.7 kJ·mo −1 ). Moreover, the 30P-Zr/SBA-15 catalyst exhibited the excellent recyclability and could be recycled at least six times without a significant loss of activity. On the basis of the temperature-programmed surface reaction of DMF and ethylene, a reasonable reaction mechanism was proposed.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Yongjin Wang,Dan Yuan,Shungang Wan,Siqin Yi,Jiangli Wu,Lei Sun
Reports on shaped porous biochar adsorbents prepared with waste biomass by co-regulation of hydrophobicity, physical structure, and chemical properties to capture air pollutants are limited. This study utilized chitin, the main component of shrimp shell waste, as the raw material to explore the formation mechanism of carbonized porous hydrochars (CPHCs), adsorption performance, and mechanisms of para-xylene (PX) onto CPHCs. The optimal preparation conditions were determined as follows: 1.68 mL of H 2 SO 4 , 0.84 mL of H 3 PO 4 (H 3 PO 4 :H 2 SO 4 = 1:2, with a total acid volume of 2.50 mL), 12.50 g of phenol, liquefaction temperature of 150 °C, liquefaction time of 2 h, 5.20 g of NaOH, hydrothermal time of 12 h, hydrothermal temperature of 130 °C, a mixture ratio of 1:2.4 for chitin powder and ZnCl 2 , and a calcination temperature of 500 °C. The resulting CPHCs exhibited uniform size, high mechanical strength, and abundant micropores. The BET specific surface area, total pore volume, micropore volume, and water contact angle of CPHCs were 751.81 m 2 /g, 0.32 cm 3 /g, 0.16 cm 3 /g, and 120°, respectively. The adsorption of PX followed pseudo-first-order kinetics and Langmuir isotherm model, with a maximum adsorption capacity of 302.11 mg/g. The adsorption process was endothermic and spontaneous. The main mechanisms of PX adsorption on CPHCs involved hydrogen bonding, π-π interactions, and micro-pore filling. The preparation of shaped hydrophobic biomass materials using chitin powder is feasible, and CPHCs exhibited excellent capture performance for PX.
研究领域:
环境科学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2020
·
IF 2.888
Midong Shi,Wei Zeng,Shixian Song,Meiting Zhou,Wei Wang
Liquid-liquid equilibrium (LLE) data for {n-heptane + p-xylene (PX) + furfural/dimethyl sulfoxide (DMSO)} ternary systems were measured at 303.15 K and 323.15 K and atmospheric pressure. Extraction performance of furfural and DMSO were evaluated using distribution coefficient (D) and selectivity (S) according to the measured tie-line data. And the results showed that DMSO had better extraction performance than furfural for separation of n-heptane and PX. Both UNIQUAC and NRTL models were used to correlate the experimental LLE data, and relevant interaction parameters were obtained. Consistency between the measured LLE data and the calculated by these two models was well evaluated by RMSD and maximum absolute deviation. Moreover, reliability of binary interaction parameters was confirmed by topological analysis related to the Gibbs tangent plane test.
研究领域:
化学工程
·
物理化学
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产品关联
DOI
高影响因子
JOURNAL OF SOLUTION CHEMISTRY
·
2022
·Vol. 51
·期 10
·1247-1267
·
IF 2
Yu Yingmin,Li Min,Liu Lanmu,Li Jun,Song Yuhe
In this paper, the separation of the p-xylene and ethylbenzene was explored. The COSMO-SAC-UNIFAC model, σ-profile analysis, solvent power and selectivity were used to screen for a suitable solvent for this process. Then, 1,2,4-trichlorobenzene was selected as target solvent to extract the p-xylene from ethylbenzene. The vapor–liquid-phase equilibrium (VLE) data for binary systems of p-xylene + ethylbenzene, p-xylene + 1,2,4-trichlorobenzene, and ethylbenzene + 1,2,4-trichlorobenzene and ternary system of p-xylene + ethylbenzene + 1,2,4-trichlorobenzene were determined with a modified Rose still at atmospheric pressure (101.3 kPa) and all the binary data passed the Wisniak’s test, which accorded with the thermodynamic consistency. Three thermodynamic models, Wilson, NRTL and UNIQUAC were used to correlate the VLE data and get binary interaction parameters, then the ternary VLE data of p-xylene + ethylbenzene + 1,2,4-trichlorobenzene were estimated based on these model parameters using Aspen Plus V10. The estimation values of the three models are in good agreement with the experimental data. Moreover, the effect of 1,2,4-trichlorobenzene was analyzed and it was found to be an effective candidate extractant for the extractive distillation of ethylbenzene from mixed xylenes.
研究领域:
化学工程
·
热力学
✓ 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
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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
·
化学工程
·
分离技术
✓ 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）