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Exergy and exergoeconomic analyses for integration of aromatics separation with aromatics upgrading

《化学科学与工程前沿（英文）》 2023年第17卷第2期页码 183-193 doi: 10.1007/s11705-022-2192-9

摘要： Methanol to aromatics produces multiple products, resulting in a limited selectivity of xylene. Aromatics upgrading is an effective way to produce more valuable xylene product, and different feed ratios generate discrepant product distributions. This work integrates the aromatics separation with toluene disproportionation, transalkylation of toluene and trimethylbenzene, and isomerization of xylene and trimethylbenzene. Exergy and exergoeconomic analyses are conducted to give insights in the splitting ratios of benzene, toluene and heavy aromatics for aromatics upgrading. First, a detailed simulation model is developed in Aspen HYSYS. Then, 300 splitting ratio sets of benzene and toluene for conversion are studied to investigate the process performances. The results indicate that there are different preferences for the splitting ratios of benzene and toluene in terms of exergy and exergoeconomic performances. The process generates lower total exergy destruction when the splitting ratio of toluene varies between 0.07 and 0.18, and that of benzene fluctuates between 0.55 and 0.6. Nevertheless, the process presents lower total product unit cost with the splitting ratio of toluene less than 0.18 and that of benzene fluctuating between 0.44 and 0.89. Besides, it is found that distillation is the biggest contributor to the total exergy destruction, accounting for 94.97%.

关键词： aromatics separation and upgrading variant splitting ratios total exergy destruction total product unit cost

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Microbial remediation of aromatics-contaminated soil

Ying Xu, Ning-Yi Zhou

《环境科学与工程前沿（英文）》 2017年第11卷第2期 doi: 10.1007/s11783-017-0894-x

摘要： Aromatics-contaminated soils were successfully remediated with adding single strains. Bacterial or fungal consortia were successfully used in the cases of bioaugmentation. Microbes combined with chemical or biological factors increase remediation efficiency. The environmental factors had appreciable impacts on the bioaugmentation. Aromatics-contaminated soil is of particular environmental concern as it exhibits carcinogenic and mutagenic properties. Bioremediation, a biological approach for the removal of soil contaminants, has several advantages over traditional soil remediation methodologies including high efficiency, complete pollutant removal, low expense and limited or no secondary pollution. Bioaugmentation, defined as the introduction of specific competent strains or consortia of microorganisms, is a widely applied bioremediation technology for soil remediation. In this review, it is concluded which several successful studies of bioaugmentation of aromatics-contaminated soil by single strains or mixed consortia. In recent decades, a number of reports have been published on the metabolic machinery of aromatics degradation by microorganisms and their capacity to adapt to aromatics-contaminated environments. Thus, microorganisms are major players in site remediation. The bioremediation/bioaugmentation process relies on the immense metabolic capacities of microbes for transformation of aromatic pollutants into essentially harmless or, at least, less toxic compounds. Aromatics-contaminated soils are successfully remediated with adding not only single strains but also bacterial or fungal consortia. Furthermore several novel approaches, which microbes combined with physical, chemical or biological factors, increase remediation efficiency of aromatics-contaminated soil. Meanwhile, the environmental factors also have appreciable impacts on the bioaugmentation process. The biostatistics method is recommended for analysis of the effects of bioaugmentation treatments.

关键词： Aromatics-contaminated soil Bacteria Bioaugmentation Bioremediation Fungi

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The influence of chlorinated aromatics' structure on their adsorption characteristics on activated carbon

Pengfei LIN,Yuan ZHANG,Xiaojian ZHANG,Chao CHEN,Yuefeng XIE,Irwin H SUFFET

《环境科学与工程前沿（英文）》 2015年第9卷第1期页码 138-146 doi: 10.1007/s11783-014-0725-2

摘要： This study focused on evaluating the efficiency of powdered activated carbon (PAC) adsorption process and tackling chlorobenzenes and chlorophenols spill in drinking water source. The adsorption kinetics and PAC’s capacities for five chlorobenzenes and three chlorophenols at drinking water contamination levels were studied in order to determine the influence of different functional groups on the adsorption behavior. The results showed that PAC adsorption could be used as an effective emergency drinking water treatment process to remove these compounds. The adsorption kinetics took 30 min to achieve nearly equilibrium and could be described by both pseudo first-order and pseudo second-order models. A mathematic relationship was developed between the pseudo first-order adsorption rate constant, k , and the solutes’ properties including lg , polarizability and molecular weight. The Freundlich isotherm equation could well describe the adsorption equilibrium behaviors of chlorinated aromatics with from 0.920 to 0.999. The H-bond donor/acceptor group, hydrophobicity, solubility and molecular volume were identified as important solute properties that affect the PAC adsorption capacity. These results could assist water professionals in removing chlorinated aromatics during emergency drinking water treatment.

关键词： chlorinated aromatics adsorption powdered activated carbon kinetics equilibrium

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Enhancing the aromatic selectivity of cyclohexane aromatization by CO₂ coupling

《化学科学与工程前沿（英文）》 2023年第17卷第11期页码 1801-1808 doi: 10.1007/s11705-023-2325-9

摘要： Improving the aromatic selectivity in the alkane aromatization process is of great importance for its practical utilization but challenge to make because the high H/C ratio of alkanes would lead to a serious hydrogen transfer process and a large amount of light alkanes. Herein, CO₂ is introduced into the cyclohexane conversion process on the HZSM-5 zeolite, which can improve the aromatic selectivity. By optimizing the reaction conditions, an improved aromatic (benzene, toluene, xylene, and C₉₊) selectivity of 48.2% can be obtained at the conditions of 2.7 MPa (CO₂), 450 °C, and 1.7 h⁻¹, which is better than that without CO₂ (aromatic selectivity = 43.2%). In situ transmission Fourier transform infrared spectroscopy spectra illustrate that many oxygenated chemical intermediates (e.g., carboxylic acid, anhydride, unsaturated aldehydes/ketones or ketene) would be formed during the cyclohexane conversion process in the presence of CO₂. ¹³C isotope labeling experimental results demonstrate that CO₂ can enter into the aromatics through the formation of oxygenated chemical intermediates and thereby improve the aromatic selectivity. This study may open a green, economic, and promising way to improve the aromatic selectivity for alkane aromatization process.

关键词： aromatics carbon dioxide aromatization coupling reaction ZSM-5 zeolite

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Co-conversion of methanol and

Shumei Wei, Yarong Xu, Zhaoyang Jin, Xuedong Zhu

《化学科学与工程前沿（英文）》 2020年第14卷第5期页码 783-792 doi: 10.1007/s11705-019-1868-2

摘要： The conversion of -hexane and methanol into value-added aromatic compounds is a promising method for their industrially relevant utilization. In this study, intergrown ZSM-5/ZSM-11 crystals were synthesized and their resulting catalytic performance was investigated and compared to those of the isolated ZSM-5 and ZSM-11 zeolites. The physicochemical properties of ZSM-5/ZSM-11 intergrown zeolite were analyzed using X-ray diffraction, N isothermal adsorption-desorption, the temperature-programmed desorption of ammonium, scanning electron microscopy, Fourier transform infrared spectra of adsorbed pyridine, and nuclear magnetic resonance of Al , and compared with those of the ZSM-5 and ZSM-11 zeolites. The catalytic performances of the materials were evaluated during the co-feeding reaction of methanol and -hexane under the fixed bed conditions of 400°C, 0.5 MPa (N ), methanol꞉ -hexane= 7꞉3 (mass ratio), and weight hourly space velocity= 1 h (methanol). Compared to the ZSM-5 and ZSM-11 zeolites, the ZSM-5/ZSM-11 zeolite exhibited the largest specific surface area, a unique crystal structure, moderate acidity, and suitable Brønsted/Lewis acid ratio. The evaluation results showed that ZSM-5/ZSM-11 catalyst exhibited better catalytic reactivity than the ZSM-5 and ZSM-11 catalysts in terms of methanol conversion rate, -hexane conversion rate, and aromatic selectivity. The outstanding catalytic property of the intergrown ZSM-5/ZSM-11 was attributed to the enhanced diffusion associated with its unique crystal structure. The benefit of using zeolite intergrowth in the co-conversion of methanol and alkanes offers a novel route for future catalyst development.

关键词： ZSM-5/ZSM-11 methanol n-hexane cofeeding aromatics

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C₈芳烃异构化催化剂的开发及应用

乔映宾

《中国工程科学》 1999年第1卷第1期页码 73-77

摘要：

文章介绍了SKI系列C₈芳烃异构化催化剂研究工作的进展。阐述了催化剂研制开发的创新思路以及该催化剂的优异性能。该催化剂采用丝光沸石固体酸取代常规的卤素酸，因此操作过程中既可省去补氯和碱洗等繁杂过程，又可避免设备腐蚀并改善了操作环境，是一种环境友好的催化剂。该催化剂可使贫对二甲苯或贫对、邻二甲苯的混合C₈芳烃异构为接近热力学平衡的C₈芳烃，C₈芳烃的选择性大于97%，使用寿命可达5年以上。并介绍了该催化剂在引进的七套C₈芳烃异构化工业装置上取代了进口催化剂，将该科技成果转化为现实的生产力所取得的成绩。

关键词：异构化催化剂二甲苯

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Alkaline modification of ZSM-5 catalysts for methanol aromatization: The effect of the alkaline concentration

Zhenhao Wei,Tengfei Xia,Minghui Liu,Qingsheng Cao,Yarong Xu,Kake Zhu,Xuedong Zhu

《化学科学与工程前沿（英文）》 2015年第9卷第4期页码 450-460 doi: 10.1007/s11705-015-1542-2

摘要： The effects of alkaline treatment on the physical properties of ZSM-5 catalysts and on their activities for methanol to aromatics conversion have been investigated. A mild alkaline treatment (0.2 and 0.3 mol/L NaOH) created mesopores in the parent zeolite with no obvious effect on acidity. The presence of mesopores gives the catalyst a longer lifetime and higher selectivity for aromatics. Treatment with 0.4 mol/L NaOH decreased the number of Brønsted acid sites due to dealumination and desilication, which resulted in a lower deactivation rate. In addition, more mesopores were produced than with the mild alkaline treatment. As a result, the lifetime of the sample treated with 0.4 mol/L NaOH was almost five times that of the parent ZSM-5. Treatment with a higher alkaline concentration (0.5 mol/L) greatly reduced the number of Brønsted acid sites and the number of micropores resulting in incomplete methanol conversion. When the alkaline-treated catalysts were washed with acid, some of the porosity was restored and a slight increase in selectivity for aromatics was obtained.

关键词： aromatics ZSM-5 alkaline treatment dealumination desilication mesopores methanol