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1. Intrinsic kinetics of catalytic hydrogenation of 2-nitro-4-acetylamino anisole to 2-amino-4-acetylamino anisole over Raney nickel catalyst
Xiangyang Cui, Xin Zhang, Baoju Wang, Yuqi Sun, Haikui Zou, Guangwen Chu, Yong Luo, Jianfeng Chen
中国化学工程学报    2023, 64 (12): 1-8.   DOI: 10.1016/j.cjche.2023.06.013
摘要148)      PDF(pc) (760KB)(307)    收藏
The catalytic hydrogenation of 2-nitro-4-acetylamino anisole (NMA) is a less-polluting and efficient method to produce 2-amino-4-acetamino anisole (AMA). However, the kinetics of catalytic hydrogenation of NMA to AMA remains obscure. In this work, the kinetic models including power-law model and Langmuir-Hinshelwood-Hougen-Watson (LHHW) model of NMA hydrogenation to AMA catalyzed by Raney nickel catalyst were investigated. All experiments were carried out under the elimination of mass transfer resistance within the temperature range of 70–100 ℃ and the hydrogen pressure of 0.8–1.5 MPa. The reaction was found to follow 0.52-order kinetics with respect to the NMA concentration and 1.10-order kinetics in terms of hydrogen pressure. Based on the LHHW model, the dual-site dissociation adsorption of hydrogen was analyzed to be the rate determining step. The research of intrinsic kinetics of NMA to AMA provides the guidance for the reactor design and inspires the catalyst modification.
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2. Enhanced ortho-selective t–butylation of phenol over sulfonic acid functionalized mesopore MTW zeolites
Baoyu Liu, Feng Xiong, Jianwen Zhang, Manna Wang, Yi Huang, Yanxiong Fang, Jinxiang Dong
中国化学工程学报    2023, 60 (8): 1-7.   DOI: 10.1016/j.cjche.2023.02.014
摘要111)      PDF(pc) (6063KB)(182)    收藏
Novel organo-inorganic hybrid materials (MTW-x-SO3H) have been fabricated by immobilizing 3-mercaptopropyltriethoxysilane onto mesopore MTW zeolites, which is treated via a simple oxidation process with hydrogen peroxide as the oxidant to transform sulfhydryl group into sulfonic acid group. The organic sulfhydryl groups are covalently bonded to the external surface of MTW zeolites through the condensation between siloxane arising from organic fragments with silanol groups on the surface of MTW zeolites, the hybrids contain sulfonic acid group within the external surface of MTW zeolites and an opened mesoporous system in the matrix of MTW zeolites, which provide enough accessible Brønsted acid sites for the alkylation between phenol with tert-butyl alcohol. Through this methodology it’s possible to prepare multifunctional materials where the plenty of mesopores are benefit for the introduction of larger numbers of sulfonic acid groups that contributes to activity during reactions, resulting in high activity (>55%) of MTW-4-SO3H and desired selectivity (>56%) of 2-TBP (2-tert-butyl phenol) in the alkylation between phenol with tert-butyl alcohol.
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3. Effects of the original state of sodium-based additives on microstructure, surface characteristics and filtration performance of SiC membranes
Yuling Xie, Qilin Gu, Qian Jiang, Zhaoxiang Zhong, Weihong Xing
中国化学工程学报    2023, 63 (11): 1-11.   DOI: 10.1016/j.cjche.2023.05.010
摘要81)      PDF(pc) (10480KB)(400)    收藏
Sodium-contained compounds are promising sintering additives for the low-temperature preparation of reaction bonded SiC membranes. Although sodium-based sintering additives in various original states were attempted, their effects on microstructure and surface properties have rarely been studied. In this work, three types of sodium-based additives, including solid-state NaA zeolite residue (NaA) and liquid-state dodecylbenzene sulfonate (SDBS) and water glass (WG), were separately adopted to prepare SiC membranes, and the microstructure, surface characteristics and filtration performance of these SiC membranes were comparatively studied. Results showed that the SiC membranes prepared with liquid-state SDBS and WG (S-SDBS and S-WG) showed lower open porosity yet higher bending strength compared to those prepared with solid-state NaA (S-NaA). The observed differences in bending strength were further interpreted by analyzing the reaction process of each sintering additive and the composition of the bonding phase in the reaction bonded SiC membranes. Meanwhile, the microstructural differentiation was correlated to the original state of the additives. In addition, their surface characteristics and filtration performance for oil-in-water emulsion were examined and correlated to the membrane microstructure. The S-NaA samples showed higher hydrophilicity, lower surface roughness (1.80 μm) and higher rejection ratio (99.99%) in O/W emulsion separation than those of S-WG and S-SDBS. This can be attributed to the smaller mean pore size and higher open porosity, resulting from the originally solid-state NaA additives. Therefore, this work revealed the comprehensive effects of original state of sintering additives on the prepared SiC membranes, which could be helpful for the application-oriented fabrication by choosing additives in suitable state.
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4. Enhancing effect of choline chloride-based deep eutectic solvents with polyols on the aqueous solubility of curcumin-insight from experiment and theoretical calculation
Wen Yu, Yiyang Bo, Yiling Luo, Xiyan Huang, Rixiang Zhang, Jiaheng Zhang
中国化学工程学报    2023, 59 (7): 160-168.   DOI: 10.1016/j.cjche.2023.01.005
摘要79)      PDF(pc) (2920KB)(10)    收藏
The development of green solvents for enhancing aqueous solubility of drug curcumin remains a challenge. This study explores the enhancing effect of deep eutectic solvents (DESs) on the aqueous solubility of curcumin (CUR) via experiment and theoretical calculation. Choline chloride-based DESs with polyols 1,2-propanediol (1,2-PDO), 1,3-propanediol, ethylene glycol, and glycerol as hydrogen bond donors were prepared and used as co-solvents. The CUR aqueous solubility increased with increasing the DESs content at temperature of 303.15-318.15 K, especially in aqueous ChCl/1,2-PDO (mole ratio 1:4) solutions. The positive apparent molar volume values and reduced density gradient analysis confirmed the existence of strong interactions between CUR and solvent. The van der Waals interactions and hydrogen bonding coexisted in DESs monomer retained the stability of DESs structure after introducing CUR. Moreover, the lower interaction energy of DESs…CUR system than that of the counterpart DESs further proved the strong interaction between CUR and DESs. The lowest interaction energy of ChCl/1,2-PDO…CUR system indicated that this system was the most stable and ChCl/1,2-PDO was promising for CUR dissolution. This work provides efficient solvents for utilizing curcumin, contributing to a deep insight into the interactions between DES and CUR at the molecular level, and the role of DESs on enhancing drugs solubility.
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5. Experiments and model development of p-nitrochlorobenzene and naphthalene purification in a continuous tower melting crystallizer
Wenlong Xiao, Yonglin Li, Zhengming Yi, Sheng Yang, He'an Luo
中国化学工程学报    2023, 64 (12): 9-17.   DOI: 10.1016/j.cjche.2023.06.004
摘要74)      PDF(pc) (1657KB)(174)    收藏
With the increasing demand for high-purity products, the industrial application of melt crystallization technology has been highly concerned. In this study, the purification process of nitrochlorobenzene binary eutectic system (NBES) and naphthalene–benzothiophene solid solution system (NBSSS) in tower melting crystallizer is analyzed, and a mathematical model of crystallization process is established. The key parameters in terms of feed concentration, crystal bed height, reflux ratio and stirring speed efficiency on purification effects were discussed by the established model. The results show that the concentration of p-nitrochlorobenzene was purified from 90.85% to 99.99%, when the crystal bed height is 600 mm, the reflux ratio is 2.5, and the stirring speed is 12 r·min-1. The naphthalene concentration is purified from 95.89% to 99.99%, when the crystal bed height is 400 mm, the reflux ratio is 1.43, and the stirring speed is 16 r·min-1. The quality of the model is evaluated by the ARD (average relative deviation). The minimum ARD values of the NBES and NBSSS are 2.39% and 5.22%, respectively, indicating the model satisfactorily explains the purification process.
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6. Co3O4 as an efficient passive NOx adsorber for emission control during cold-start of diesel engines
Jinhuang Cai, Shijie Hao, Yun Zhang, Xiaomin Wu, Zhenguo Li, Huawang Zhao
中国化学工程学报    2024, 66 (2): 1-7.   DOI: 10.1016/j.cjche.2023.10.013
摘要74)      PDF(pc) (7979KB)(178)    收藏
The Co3O4 nanoparticles, dominated by a catalytically active (110) lattice plane, were synthesized as a low-temperature NOx adsorbent to control the cold start emissions from vehicles. These nanoparticles boast a substantial quantity of active chemisorbed oxygen and lattice oxygen, which exhibited a NOx uptake capacity commensurate with Pd/SSZ-13 at 100°C. The primary NOx release temperature falls within a temperature range of 200–350°C, making it perfectly suitable for diesel engines. The characterization results demonstrate that chemisorbed oxygen facilitate nitro/nitrites intermediates formation, contributing to the NOx storage at 100°C, while the nitrites begin to decompose within the 150–200°C range. Fortunately, lattice oxygen likely becomes involved in the activation of nitrites into more stable nitrate within this particular temperature range. The concurrent processes of nitrites decomposition and its conversion to nitrates results in a minimal NOx release between the temperatures of 150–200°C. The nitrate formed via lattice oxygen mainly induces the NOx to be released as NO2 within a temperature range of 200–350°C, which is advantageous in enhancing the NOx activity of downstream NH3-SCR catalysts, by boosting the fast SCR reaction pathway. Thanks to its low cost, considerable NOx absorption capacity, and optimal release temperature, Co3O4 demonstrates potential as an effective material for passive NOx adsorber applications.
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7. Experimental investigation of the mixing efficiency via intensity of segregation along axial direction of a rotating bar reactor
Abdelgadir Bashir Banaga, Yan-Bin Li, Zhi-Hao Li, Bao-Chang Sun, Guang-Wen Chu
中国化学工程学报    2023, 59 (7): 153-159.   DOI: 10.1016/j.cjche.2023.01.003
摘要73)      PDF(pc) (2611KB)(28)    收藏
As a significant index to evaluate the mixing efficiency, studying the concentration distribution is directly related to the intensity of segregation (Is). In this work, the Is of the mixture composed of NaCl solution-water was investigated experimentally in a rotating bar reactor (RBR) by the conductivity method. The results showed that the mixing efficiency was improved along the axial direction from the bottom to the top in the RBR. The concentration distribution at the bottom section was more uneven, and Is was higher compared with the top section, which decreased from 6.53×10-5 to 1.57×10-7. With the increase of rotational speed from 0 to 700 r·min-1, Is at the bottom and top sections decreased from 4.27×10-3 to 7.10×10-5 and from 1.93×10-3 to 7.29×10-7, respectively. The increases flow rate of solution A, and the decreases of concentration of NaCl and flow rate of solution B gave rise to the reduction of Is, signifying an improved mixing efficiency. The results revealed that the conductivity method used in this paper has high efficiency and low cost to measure the, which indicates a promising prospect for estimating reactors’ mixing performance.
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8. Mechanism, behaviour and application of iron nitrate modified carbon nanotube composites for the adsorption of arsenic in aqueous solutions
Yingli Li, Zhishuncheng Li, Guangfei Qu, Rui Li, Shuaiyu Liang, Junhong Zhou, Wei Ji, Huiming Tang
中国化学工程学报    2023, 60 (8): 26-36.   DOI: 10.1016/j.cjche.2023.01.010
摘要72)      PDF(pc) (16115KB)(63)    收藏
In this study, ferric nitrate modified carbon nanotube composites (FCNT) were prepared by isovolumetric impregnation using carbon nanotubes (CNTs) as the carrier and ferric nitrates the active agent. The batch experiments showed that FCNT could effectively oxidize As(III) to As(V) and react with it to form stable iron arsenate precipitates. When the dosage of FCNT was 0.1 g·L-1, pH value was 5-6, reaction temperature was 35 ℃ and reaction time was 2 h, the best arsenic removal effect could be achieved, and the removal rate of As(V) could reach 99.1%, which was always higher than 90% under acidic conditions. The adsorption results of FCNT were found to be consistent with Langmuir adsorption by static adsorption isotherm fitting, and the maximum adsorption capacity reached 118.3 mg·g-1. The material phase and property analysis by scanning electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared spectoscopy, X-ray photoelectron spectroscopy and other characterization methods, as well as adsorption isotherm modeling, were used to explore the adsorption mechanism of FCNT on arsenic. It was found that FCNT has microporous structure and nanostructure, and iron nanoparticles are loosely distributed on CNTs, which makes the material have good oxidation, adsorption and magnetic separation properties. Arsenic migrates on the surface of FCNT composites is mainly removed by forming insoluble compounds and co-precipitation. All the results show that FCNT treats arsenic at low cost with high adsorption efficiency, and the results also provide the experimental data basis and theoretical basis for arsenic contamination in groundwater.
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9. Kinetic mechanism of copper extraction from methylchlorosilane slurry residue using hydrogen peroxide as oxidant
Xiaolin Guo, Zhaoyang Zhang, Pengfei Xing, Shuai Wang, Yibing Guo, Yanxin Zhuang
中国化学工程学报    2023, 60 (8): 228-234.   DOI: 10.1016/j.cjche.2023.02.007
摘要72)      PDF(pc) (3868KB)(65)    收藏
Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method. A number of experimental parameters were analyzed to determine the extraction efficiency of copper. The extraction efficiency of copper reached 98.5% under the optimal leaching conditions, such as the hydrogen peroxide concentration of 1.875 mol·L-1, the leaching temperature of 323 K, the liquid-solid ratio of 20 ml·g-1, and the stirring speed of 300 r?min-1. The leaching kinetics of the copper extraction process was then described by the shrinking core model. There were two stages. The first stage was controlled by chemical reactions, while the second stage was controlled by interface transfer and product layer diffusion. The activation energy and kinetic control equations were determined, as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization. Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.
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10. One-step ethylene separation from ternary C2 hydrocarbon mixture with a robust zirconium metal-organic framework
Yuan Liu, Hanting Xiong, Jingwen Chen, Shixia Chen, Zhenyu Zhou, Zheling Zeng, Shuguang Deng, Jun Wang
中国化学工程学报    2023, 59 (7): 9-15.   DOI: 10.1016/j.cjche.2023.01.001
摘要70)      PDF(pc) (8172KB)(128)    收藏
One-step separation of high-purity ethylene (C2H4) from C2 hydrocarbon mixture is critical but challenging because of the very similar molecular sizes and physical properties of C2H4, ethane (C2H6), and acetylene (C2H2). Herein, we report a robust zirconium metal-organic framework (MOF) Zr-TCA (H3TCA = 4,4',4″-tricarboxytriphenylamine) with suitable pore size (0.6 nm×0.7 nm) and pore environment for direct C2H4 purification from C2H4/C2H2/C2H6 gas-mixture. Computational studies indicate that the abundant oxygen atoms and non-polar phenyl rings created favorable pore environments for the preferential binding of C2H2 and C2H6 over C2H4. As a result, Zr-TCA exhibits not only high C2H6 (2.28 mmol·g-1) and C2H2 (2.78 mmol·g-1) adsorption capacity but also excellent C2H6/C2H4 (2.72) and C2H2/C2H4 (5.64) selectivity, surpassing most of one-step C2H4 purification MOF materials. Dynamic breakthrough experiments confirm that Zr-TCA can produce high-purity C2H4 (>99.9%) from a ternary gas mixture (1/9/90 C2H2/C2H6/C2H4) in a single step with a high C2H4 productivity of 5.61 L·kg-1.
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11. Performance comparison of lithium fractionation from magnesium via continuous selective nanofiltration/electrodialysis
Yong Xu, Qingbai Chen, Yang Gao, Jianyou Wang, Huiqing Fan, Fei Zhao
中国化学工程学报    2023, 59 (7): 42-50.   DOI: 10.1016/j.cjche.2022.11.013
摘要70)      PDF(pc) (6225KB)(114)    收藏
Although selective nanofiltration (SNF) and selective electrodialysis (SED) have been widely adopted in the field of Mg2+/Li+ separation, their differences have not been illustrated systematically. In this study, for the first time, SNF and SED processes in continuous mode were studied for Li+ fractionation from the same brine with high Mg/Li ratios and their differences were discussed in detail. For a fair analysis of the two processes, typical factors were optimized. Specifically, the optimal operating pressure and feed flow rate for SNF were 2.4 MPa and 140 L·h-1, respectively, while the optimal cell-pair voltage and replenishment flow rate for SED were 1.0 V and 14 L·h-1, respectively. Although the Li+ fractionation capacity of the two processes were similar, the selectivity coefficient of SNF was 24.7% higher than that of SED and, thus, the Mg/Li ratio in purified stream of the former was 19.0% lower than that of the latter. Due to higher ion driving force, SED had clear advantages in recovery ratio and concentration effects. Meanwhile, the specific energy consumption of SED was 20.1% lower than that of SNF. This study provided a better understanding and guidance for the application and improvement of the two technologies.
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12. Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation, one-stage urea complexation and five-stage solvent crystallization
Yingxi Gao, Jiayi Shi, Jie Wang, Fan Zhang, Shichao Tian, Zhiyong Zhou, Zhongqi Ren
中国化学工程学报    2023, 59 (7): 61-71.   DOI: 10.1016/j.cjche.2022.10.007
摘要69)      PDF(pc) (5583KB)(103)    收藏
Nervonic acid is the world's first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value. The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult. A new combined process of molecular distillation, urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials. First, according to the difference in the mean free path of fatty acids, molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18-C20 fatty acids of stearic, oleic, linoleic, and linolenic acids. The content of C16-C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes, in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%. Then, according to the difference in carbon chain length and saturation of fatty acid, the contents of C22-C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification (SPOMFs) ratio as 0.6. In addition, all saturated fatty acids were basically separated. Finally, according to the difference in the solubility of fatty acids in solvents, the C18-C20 unsaturated fatty acids of oleic, linoleic, and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization. The content of C18-C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization. The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization. The combined process of molecular distillation, urea inclusion and low temperature crystallization innovatively adopted an efficient, simple and easy-to-industrial solvent crystallization method to separate erucic and nervonic acids, obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.
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13. Arsenic removal from acidic industrial wastewater by ultrasonic activated phosphorus pentasulfide
Bo Yu, Guang Fu, Xinpei Li, Libo Zhang, Jing Li, Hongtao Qu, Dongbin Wang, Qingfeng Dong, Mengmeng Zhang
中国化学工程学报    2023, 60 (8): 46-52.   DOI: 10.1016/j.cjche.2023.02.002
摘要69)      PDF(pc) (4252KB)(137)    收藏
Arsenic is one of the main harmful elements in industrial wastewater. How to remove arsenic has always been one of the research hotspots in academic circles. In the process of arsenic removal by traditional sulfuration, the use of traditional sulfurizing agent will introduce new metal cations, which will affect the recycling of acid. In this study, phosphorus pentasulfide (P2S5) was used as sulfurizing agent, which hydrolyzed to produce H3PO4 and H2S without introducing new metal cations. The effect of ultrasound on arsenic removal by P2S5 was studied. Under the action of ultrasound, the utilization of P2S5 was improved and the reaction time was shortened. The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions. Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5% could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min. In the first 60 min, under the same S/As molar ratio and reaction time, the ultrasonic hydrolysis efficiency of P2S5 was higher. This is because P2S5 forms ([(P2S4)])2+ under the ultrasonic action, and the structure is damaged, which is easier to be hydrolyzed. In addition, the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy. Our research avoids the introduction of metal cations in the arsenic removal process, and shortens the reaction time.
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14. Experimental verification of nanonization enhanced solubility for poorly soluble optoelectronic molecules
Jingzhou Guo, Yuanzuo Zou, Bo Shi, Yuan Pu, Jiexin Wang, Dan Wang, Jianfeng Chen
中国化学工程学报    2023, 60 (8): 8-15.   DOI: 10.1016/j.cjche.2023.02.017
摘要69)      PDF(pc) (7248KB)(67)    收藏
Solubility enhancement has been a priority to overcome poor solubility with optoelectronic molecules for solution-processable devices. This study aims to obtain experimental data on the effect of particle sizes on the solubility properties of several typical optoelectronic molecules in organic solvents, including the solubility results of 1,3-bis(9-carbazolyl)benzene (mCP), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) and 2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole (PBD) in ethanol and acetonitrile, respectively. Nanoparticles of mCP, TPBi and PBD with sizes from dozens to several hundred nanometers were prepared by solvent antisolvent precipitation method and their solubility were determined by using isothermal saturation method. The saturation solubility of nanoparticles of three kinds of optoelectronic molecules exhibited increase of 12.9%-25.7% in comparison to the same raw materials in the form of microparticles. The experimental evidence indicates that nanonization technology is a feasible way to make optoelectronic molecules dissolve in liquids with enhanced solubility.
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15. Numerical simulation of flow and heat transfer of n-decane in sub-millimeter spiral tube at supercritical pressure
Jiahao Xing, Huaizhi Han, Ruitian Yu, Wen Luo
中国化学工程学报    2023, 60 (8): 173-185.   DOI: 10.1016/j.cjche.2023.02.005
摘要68)      PDF(pc) (5876KB)(30)    收藏
The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube (SMST) at supercritical pressure (p = 3 MPa) are studied by the RNG k -ε numerical model in this paper. The effects of various Reynolds numbers (Re) and structural parameters pitch (s) and spiral diameter (D) are analyzed. Results indicate that the average Nusselt number (f) and friction factor (Nu) increase with an increase in Re, and decrease with an increase in D/d (tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu and f first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve f by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.
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16. High catalytic performance of CuCe/Ti for CO oxidation and the role of TiO2
Tingting Chang, Ziyan Wang, Zhimiao Wang, Hualiang An, Fang Li, Wei Xue, Yanji Wang
中国化学工程学报    2023, 62 (10): 1-10.   DOI: 10.1016/j.cjche.2023.08.004
摘要68)      PDF(pc) (8649KB)(90)    收藏
CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO2 (TiO2-A) and rutile TiO2 (TiO2-R) as supports using the incipient wetness impregnation method for the carbon monoxide (CO) oxidation reaction and were compared with a CuCe-C catalyst prepared using the co-precipitation method. The CuCe/Ti-A catalyst exhibited the highest activity, with complete CO conversion at 90 ℃, when the gas hourly space velocity was 24000 ml·g-1·h-1 and the CO concentration was approximately 1% (vol). A series of characterizations of the catalysts revealed that the CuCe/Ti-A catalyst has a larger specific surface area, more Cu+ species and oxygen vacancies, and the Cu species of CuCe/Ti-A catalyst is more readily reduced. In situ FT-IR results indicate that the bicarbonate species generated on the CuCe/Ti-A catalyst have lower thermal stability than the carbonate species on CuCe/Ti-R, and will decompose more readily to form CO2. Therefore, CuCe/Ti-A has excellent catalytic activity for CO oxidation.
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17. Facile modification of aluminum hypophosphate and its flame retardancy for polystyrene
Wensheng Li, Liangyuan Qi, Daolin Ye, Wei Cai, Weiyi Xing
中国化学工程学报    2023, 60 (8): 90-98.   DOI: 10.1016/j.cjche.2023.02.001
摘要66)      PDF(pc) (8595KB)(30)    收藏
A phosphorus-containing flame retardant, aluminum hypophosphite (AHPi), has been modified by (3-aminopropyl) triethoxysilane (KH550) to prepare flame-retardant polystyrene (PS). The influence of modified AHPi on the morphology and characterization was investigated, and differences in flame retardant properties of the PS/AHPi and PS/modified AHPi were compared. The PS composite can pass the vertical burning tests (UL-94 standard) with a V-0 rating when the mass content of modified AHPi reaches 20%, compared with the mass content of 25% AHPi. The element mapping of the PS composite shows that modified AHPi has better dispersion in PS than AHPi. Thermogravimetric analysis results indicated that adding modified AHPi can advance the initial decomposition temperature of the composite material. With the addition of modified AHPi, the decrease in peak heat release rate (pHRR) is more evident than AHPi, and the char yield of the resultant PS composites gradually increased. With the addition of 25% modified AHPi, the pHRR and total heat release of PS composites decreased by 81.4% and 37.6%. The modification of AHPi promoted its dispersion in the PS matrix and improved the char formation of PS composites. The results of real-time infrared spectrometry of PS composites, Fourier transform infrared spectra and X-ray photoelectron analysis of the char layer indicated that modified AHPi has flame retardancy in condensed and gas phases.
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18. Tungsten incorporated mobil-type eleven zeolite membranes: Facile synthesis and tuneable wettability for highly efficient separation of oil/water mixtures
Hammad Saulat, Jianhua Yang, Tao Yan, Waseem Raza, Wensen Song, Gaohong He
中国化学工程学报    2023, 60 (8): 242-252.   DOI: 10.1016/j.cjche.2023.02.022
摘要66)      PDF(pc) (13733KB)(42)    收藏
Tungsten (W) incorporated mobil-type eleven (MEL) zeolite membrane (referred to as W-MEL membrane) with high separation performance was firstly explored for the separation of oil/water mixtures under the influence of gravity. W-MEL membranes were grown on stainless steel (SS) meshes through in-situ hydrothermal growth method facilitated with (3-aminopropyl)triethoxysilane (APTES) modification of stainless steel meshes, which promote the heterogeneous nucleation and crystal growth of W-MEL zeolites onto the mesh surface. W-MEL membranes were grown on different mesh size supports to investigate the effect of mesh size on the separation performance of the membrane. The as-synthesized W-MEL membrane supported on 500 mesh (25 μm) (W-MEL-500) exhibit the hydrophilic nature with a water contact angle of 11.8° and delivers the best hexane/water mixture separation with a water flux and separation efficiency of 46247 L·m-2·h-1 and 99.5%, respectively. The wettability of W-MEL membranes was manipulated from hydrophilic to hydrophobic nature by chemically modifying with the fluorine-free compounds (hexadecyltrimethoxysilane (HDTMS) and dodecyltrimethoxysilane (DDTMS)) to achieve efficient oil-permselective separation of heavy oils from water. Among the hydrophobically modified W-MEL membranes, W-MEL-500-HDTMS having a water contact angle of 146.4° delivers the best separation performance for dichloromethane/water mixtures with a constant oil flux and separation efficiency of 61490 L·m-2·h-1 and 99.2%, respectively along with the stability tested up to 20 cycles. Both W-MEL-500-HDTMS and W-MEL-500-DDTMS membranes also exhibit similar separation performances for the separation of heavy oil from sea water along with a 20-fold lower corrosion rate in comparison with the bare stainless-steel mesh, indicating their excellent stability in seawater. Compared to the reported zeolite membranes for oil/water separation, the as-synthesized and hydrophobically modified W-MEL membranes shows competitive separation performances in terms of flux and separation efficiency, demonstrating the good potentiality for oil/water separation.
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19. Crystalline-magnetism action in biomimetic mineralization of calcium carbonate
Chaoqun Wu, Xun Liu, Fujun Yao, Xin Yang, Yan Wang, Wenyuan Hu
中国化学工程学报    2023, 59 (7): 146-152.   DOI: 10.1016/j.cjche.2023.01.004
摘要66)      PDF(pc) (7478KB)(35)    收藏
The influence of minor environmental factors, such as the geomagnetic field, on the biomineralization of nacres, is often ignored but a great deal of research has confirmed its important role in the normal mineralization of calcium carbonate. Although the geomagnetic field is weak, its cumulative effects need to be considered given that the biomineralization process can take years. Accordingly, the authors of this paper have investigated the effects of weak magnetic fields (25 Gs or 50 Gs) on calcium carbonate mineralization and analyzed the mechanism involved. The results show that even a weak magnetic field conduces to the formation of vaterite or aragonite, in the induction order of precursor → vaterite → aragonite. The stronger the magnetic field and the longer the time, the more obvious the induction effect. The effect of a magnetic field is strongest in the aging stage and weakest in the solution stage. Inductions by egg-white protein and by a magnetic field inhibit each other, but they both restrict particle growth. These findings highlight the importance of minor environmental factors for biomineralization and can serve as a reference for biomimetic preparation of a CaCO3 nacre-like structure and for anti-scale technology for circulating cooling water.
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20. Reconstruction and recovery of anatase TiO2 from spent selective catalytic reduction catalyst by NaOH hydrothermal method
Jinlong Liu, Chenye Wang, Xingrui Wang, Chen Zhao, Huiquan Li, Ganyu Zhu, Jianbo Zhang
中国化学工程学报    2023, 60 (8): 53-60.   DOI: 10.1016/j.cjche.2023.03.019
摘要65)      PDF(pc) (11755KB)(66)    收藏
The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste. A novel process to recover anatase titanium dioxide (TiO2) from spent SCR catalysts was proposed. The process included alkali (NaOH) hydrothermal treatment, sulfuric acid washing, and calcination. Anatase TiO2 in spent SCR catalyst was reconstructed by forming Na2Ti2O4(OH)2 nanosheet during NaOH hydrothermal treatment and H2Ti2O4(OH)2 during sulfuric acid washing. Anatase TiO2 was recovered by decomposing H2Ti2O4(OH)2 during calcination. The surface pore properties of the recovered anatase TiO2 were adequately improved, and its specific surface area (SSA) and pore volume (PV) were 85 m2·g-1 and 0.40 cm3·g-1, respectively. The elements affecting catalytic abilities (arsenic and sodium) were also removed. The SCR catalyst was resynthesized using the recovered TiO2 as raw material, and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst. This study realized the sustainable recycling of anatase TiO2 from spent SCR catalyst.
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