RSC Advances
·
2015
·Vol. 5
·期 89
·73083-73090
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IF 3.84
Kuiyi You,Renjie Deng,Jian Jian,Pingle Liu,Qiuhong Ai,He’an Luo
Developing a new environmentally friendly process for benzene nitration to nitrobenzene has been highly desirable for a long time. In this work, NO2 was used as a nitration agent to replace traditional nitric acid, and different mesoporous SiO2 and their supported heteropoly acid (salt) were employed to catalyze benzene nitration to nitrobenzene. Several typical catalysts were characterized using XRD, BET and FT-IR, and the acid amounts of the various catalysts were determined. The effects of various factors such as different catalysts, the molar ratio of benzene to NO2, reaction temperature, reaction time, HPW loading, the acid amounts of the catalyst and the reuse of the catalyst on the nitration reaction have also been systematically examined. The results indicate that the supported HPW/MCM-41 catalysts exhibit a remarkably synergistic catalytic performance on the nitration reaction of benzene to nitrobenzene. In particular, the 50%HPW/MCM-41 catalyst gives the best results with 73.4% benzene conversion and 98.8% selectivity to nitrobenzene under the optimal reaction conditions. Moreover, the mesoporous structure of MCM-41 was retained under the high loading of HPW. The possible reaction mechanism for the nitration reaction of benzene with NO2 over HPW/MCM-41 is suggested in the present work. This method provides a promising strategy for the preparation of nitro-aromatic compounds from a catalytic nitration reaction by using NO2 as the nitration reagent.
研究领域:
化学工程
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环境科学
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DOI
高影响因子
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
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2021
·Vol. 32
·期 6
·1270-1276
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IF 1.838
Liu Jianan,Wang Yanan,Gong Shuwen,Duan Wenzeng,Huang Xianqiang
A highly efficient and reusable catalyst QA-HPMV was successfully prepared by the reaction of quinoline-2-formic acid (QA) with molybdovanadophosphoric heteropolyacid (H4PMo11VO40, HPMV) for the nitration of benzene. The physical and chemical properties of the sample was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis and thermogravimetric analysis (TG). The characterization results showed that the formed QA-HPMV retained the Keggin structure of HPMV. As a catalyst for benzene nitration, QA-HPMV showed good catalytic performance and the yield of nitrobenzene was 82.5% under the optimized reaction conditions. As a heterogeneous catalyst, QA-HPMV can be easily recycled from the reaction medium by filtering and remained highly catalytic performance even after five runs of recycling.
研究领域:
化学工程
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催化化学
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DOI
高影响因子
Catalysis Science & Technology
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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
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材料科学
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DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2017
·Vol. 11
·期 2
·205-210
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IF 1.712
Zhou Shenghui,You Kuiyi,Yi Zhengming,Liu Pingle,Luo He’an
Metal salts with highly electronegative cations have been used to effectively catalyze the liquid-phase nitration of benzene by NO 2 to nitrobenzene under solvent-free conditions. Several salts including FeCl 3 , ZrCl 4 , AlCl 3 , CuCl 2 , NiCl 2 , ZnCl 2 , MnCl 2 , Fe(NO 3 ) 3 ∙9H 2 O, Bi (NO 3 ) 3 ∙5H 2 O, Zr(NO 3 ) 4 ∙5H 2 O, Cu(NO 3 ) 2 ∙6H 2 O, Ni (NO 3 ) 2 ∙6H 2 O, Zn(NO 3 ) 2 ∙6H 2 O, Fe 2 (SO 4 ) 3 , and CuSO 4 were examined and anhydrous FeCl 3 exhibited the best catalytic performance under the optimal reaction conditions. The benzene conversion and selectivity to nitrobenzene were both over 99%. In addition, it was determined that the metal counterion and the presence of water hydrates in the salt affects the catalytic activity. This method is simple and efficient and may have potential industrial application prospects.
研究领域:
化学工程
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催化化学
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DOI
高影响因子
Journal of Flow Chemistry
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2023
·Vol. 13
·期 3
·311-323
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IF 2.7
Song Jing,Cui Yongjin,Wang Yujun,Wang Kai,Deng Jian,Luo Guangsheng
The nitration of toluene with mixed acid is one of the most representative nitration reactions. Accurate kinetic study is essential for controlling the reaction and designing reactors. Due to the characteristics of fast rate, high exothermicity and heterogeneity in toluene nitration, the effects of mass and heat transfer may result in inaccurate determination of kinetics. In this work, the adiabatic temperature rises of the reaction system were studied to provide precise ranges of experimental conditions for accurately controlling the reaction rate and heat release rate in a liquid–liquid microflow system. The adiabatic temperature rise was successfully controlled to below 0.3 °C. The effects of mass and heat transfer on the reaction rate were completely eliminated, so that the kinetic study was carried out under the control of intrinsic kinetics only. The activation energy for toluene nitration was determined to be 28.00 kJ/mol. The activation energies for the formation of o -nitrotoluene and p -nitrotoluene were obtained for the first time, which were 25.71 and 31.91 kJ/mol, respectively. The obtained kinetic models can predict the reaction performance of toluene nitration very well.
研究领域:
化学工程
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反应动力学研究
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DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
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IF 4.1
Rao Chen,Chaoqun Yao,Shuainan Zhao,Xuan Liu,Yingjiang Lian,Guangwen Chen
It is critical for reactor design and process safety to determine the reaction kinetics for toluene nitration. Herein, a continuous-flow platform based on capillary microreactors was established. First, reaction regimes for toluene nitration and its consecutive side reaction (MNT (mononitrotoluene) nitration) were identified. On this basis, the influence of process parameters on conversion of toluene, selectivity of MNT and DNT (dinitrotoluene) and their isomer distribution were meticulously examined, including molar ratio of reactants, sulfuric acid strength, reaction temperature, and residence time. Subsequently, reaction kinetic models coupled with mass transfer were developed, allowing the simultaneous kinetic determination for toluene nitration and MNT nitration. It was found that the logarithm of the observed kinetic constant is proportional to the sulfuric acid strength. The kinetic parameters under 72.7 to 80.1 wt% sulfuric acid strengths were obtained. The outcomes provide a basis for process intensification and optimization of toluene nitration as well as other similar aromatics.
研究领域:
化学工程
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过程强化
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高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
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2023
·Vol. 101
·期 12
·6807-6816
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IF 2.1
Renjie Deng,Wenjin Ni,Yao Tian
Bimetallic cerium-manganese modified Hβ zeolite sample (Ce/Mn-Hβ) was prepared by ultrasonic assisted impregnation method and applied in nitration of toluene. The characterization results show that the active components (Ce and Mn) are successfully introduced into the framework of Hβ zeolite. The catalyst shows excellent catalytic activity and reusability for the nitration of toluene, giving high para selectivity. Under optimized conditions, it gives 68.7% selectivity to para -nitrotoluene at 88.6% conversion over Ce/Mn-Hβ in the presence of acetic anhydride (Ac 2 O). The theoretical calculations indicate that the Ce/Mn bimetallic active sites in modified Hβ zeolite can easily activate the nitrification reagent (AcONO 2 ), and the enhancement of para selectivity is owing to the steric hindrance of catalyst. Furthermore, the reaction mechanism was proposed by the combination of experimental results and theoretical calculations.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
·
IF 15.1
Shuai Guo,Le-wu Zhan,Bin-dong Li
Nitration reactions are extensively studied in organic synthesis despite their notorious dangers, high reaction rates, and heterogeneous reaction systems. To date, most industrial nitration reactions rely on conventional batch reactors characterized by low mass transfer rates and limited reaction conditions. In contrast, microreactors represent a valuable technology for intensifying such nitration reactions. In this work, we established a continuous flow system of o -xylene nitration and determined the kinetics and mass transfer. The effects of mixing performance, nitric acid concentration, molar ratio, reaction temperature, and residence time on the process safety were investigated separately. The experimental data is supported by dimensionless number calculations, providing a more comprehensive understanding of the nitration reaction's transport and reaction performance in a heart-shaped microreactor. Remarkably, the residence time of the heart-shaped microreactor was reduced by an order of magnitude, while the volumetric mass transfer coefficient was improved by several orders of magnitude compared to conventional stirred tank reactors. Moreover, the spent nitric acid could be efficiently recovered and reused after concentration, further enhancing the sustainability and cost-effectiveness of the process. Our findings demonstrate the significant potential of microreactors for intensifying nitration reactions and paving the way for the design and optimization of more efficient and safer synthetic processes.
研究领域:
化学工程
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有机合成
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DOI
高影响因子
Chemical Engineering and Processing-Process Intensification
·
2022
·
IF 4.264
Shuai Guo,Jian-yang Cao,Mei-qi Liu,Le-wu Zhan,Bin-dong Li
Microreactors are becoming an important tool for rapid exothermic chemical reaction process intensification and continuous flow chemistry. This work focuses on the process intensification and kinetics of the trifluoromethylbenzen nitration in microreactors. The reaction of trifluoromethylbenzene with mixed acid is a typical liquid-liquid heterogeneous reaction, so the mass transfer is the rate-determining step. Two strategies of microreaction systems were established to enhance mass transfer, respectively. Firstly, a scheme for intensifying the nitration reaction process in a capillary microreactor was proposed. The results showed that the conversion was low and could not achieve the expected results. Finally, a Heart-type micromixer with barriers was used to improve the mixing and mass transfer performance. The effects of molar ratio, temperature, sulfuric acid concentration, flow rate, and residence time on the conversion were investigated. The results showed that the residence time was significantly reduced from 4 hours in the batch reactor to 30 s in the Heart-type micromixer. The volume mass transfer coefficient and space-time yield were up to 0.031 s −1 and 16053.55 g·cm −3 ·h −1 , respectively. Meanwhile, to better understand and control the nitration reaction process, the kinetics of the nitration of trifluoromethylbenzene was reported for the first time in a capillary microreactor, and all kinetic data were obtained.
研究领域:
化学工程
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反应工程
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DOI
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
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2023
·
IF 7.8
Hang Yao,Gang Fu,Yuqing Ni,Lei Ni,Juncheng Jiang,Han Zhang,Zhen Cheng,Zhiquan Chen
Nitro-m-xylenes (NMX) was synthesized in semi-batch mode via m-xylene nitration using nitric acid-acetic anhydride (HNO 3 -Ac 2 O) as nitrating reagent in this work. The nitration process was optimized by response surface methodology . The yield of NMX could reach 92.40% under the optimal conditions of jacket temperature of 20 °C, 0.15 mol of HNO 3 and 0.19 mol of Ac 2 O. Corresponding large reaction enthalpy (Δ H =240.9 kJ/mol) and adiabatic temperature rise (Δ T ad,r =398.1 K) indicated the serious hazards of nitration in a thermal runaway scenario. Pyrolysis of nitration products occurred at about 320–400 °C by differential scanning calorimetry tests. The reaction order of the pyrolysis was determined to be 1.2 by adiabatic kinetic analysis . Thermal risk of the nitration process was assessed to be acceptable and level 1 via the risk matrix and Stoessel criticality diagram analyses, respectively. Furthermore, detailed nitration mechanisms for NO 2 + generation and aromatic substitution were presented. The activation free enthalpy and free energy parameters for each step were calculated by density functional theory (DFT). These findings can help understand the exothermic sources of m-xylene nitration and guide the intrinsically safer design and scale-up of the process.
研究领域:
化学工程
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安全科学
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理论化学
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2024
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IF 5.3
Hang Yao,Jialei Huang,Yuqing Ni,Gang Fu,Lei Ni,Juncheng Jiang,Yong Pan
Selection of appropriate solvents is of great significance for achieving efficient and safe m-xylene nitration . In this study, the exothermic behavior of m-xylene nitration under twelve organic solvents were studied by reaction calorimetry. The process hazards were assessed by calculation of thermal safety parameters. The reaction selectivity was quantified. The anhydrides exhibited the prominent promotion as water absorbent and active reagent in nitration, followed by selected aliphatic hydrocarbons, chlorinated hydrocarbons. While acetic acid, propionic acid and ethyl acetate had negative effects. The maximum yield of 95.6 % was achieved in nitric acid-acetic anhydride (HNO 3 -Ac 2 O) system. The thermal weight loss of the products appeared at around 150−230 °C by thermogravimetry experiments. The activation energy was determined to be 192.9 kJ/mol through adiabatic kinetic calculations. Furthermore, the solvent effects were analyzed by calculating the solvent polarity and its interaction energy with HNO 3 . The different action mechanisms of Ac 2 O and Pc 2 O on NO 2 + generation were revealed. The density functional theory calculations were in agreement with the experimental results. These findings can provide guidance for understanding of the solvent effect on the reaction hazards and selectivity of m-xylene nitration, and provide experimental and theoretical basis for solvent screening for the nitration of similar aromatic compounds.
研究领域:
化学工程
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理论化学
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2024
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IF 5.3
Hang Yao,Jialei Huang,Yuqing Ni,Zhen Cheng,Gang Fu,Lei Ni,Juncheng Jiang,Yong Pan
Five imidazole based SO 3 H-functionalized ionic liquids (SFILs) with different anions were selected as catalysts to achieve efficient m-xylene nitration. The acidity and thermal stability of the ILs were characterized by UV–vis and thermogravimetry. The reaction selectivity of the m-xylene nitration catalyzed by five ILs was compared. [MIMBs]HSO 4 had the best catalytic activity with the maximum yield of 98.1 %. The effect of ILs on the exothermic behavior of m-xylene nitration was explored by reaction calorimeter. The reaction enthalpy (Δ H ) and adiabatic temperature rise (Δ T ad ) were calculated to evaluate process hazards. The reaction order for the decomposition of different nitration products under adiabatic conditions was essentially close to 1. The process risk level for m-xylene nitration with the introduction of selected ILs was essentially downgraded from conditionally acceptable to acceptable, and the criticality was reduced from class 3 to 1. Furthermore, the acidic active sites of the ILs were predicted by the electrostatic potential. The solubility of m-xylene in the IL was investigated through the calculation of interaction energy. The roles of ILs as solvents and catalysts in nitration were resolved by density functional theory calculations. These findings could contribute to the understanding of the effect of ILs in modulating the process hazards and improving the selectivity of m-xylene nitration, and provide theoretical guidance for elucidating the catalytic mechanism of ILs in nitration.
研究领域:
化学工程
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催化化学
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DOI
高影响因子
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