Pub Date : 2024-10-29DOI: 10.1016/j.ces.2024.120875
Tobias Seidel , Lorenz T. Biegler
This work addresses the complexities of optimizing the number of stages in a distillation column, which typically lead to challenging non-linear mixed-integer optimization problems. To simplify this, we employ distributed streams, thereby eliminating discrete degrees of freedom. To avoid sophisticated initialization procedures, the optimization problem is reformulated by employing a sequence of stage-to-stage calculations, each reduced to maintaining only the MESH (mass, equilibrium, summation, heat) equations for a single stage.
Our numerical experiments show the efficiency and stability of solving the simplified optimization problem in various scenarios, including single and multiple distillation columns. For a single column scenario, we compare the accuracy of our optimization method with a full enumeration approach. Additionally, for a pressure swing flowsheet designed to separate an azeotropic mixture, we illustrate potential energy savings by optimizing a stage distribution versus using a predetermined stage distribution.
{"title":"Distillation column optimization: A formal method using stage-to stage computations and distributed streams","authors":"Tobias Seidel , Lorenz T. Biegler","doi":"10.1016/j.ces.2024.120875","DOIUrl":"10.1016/j.ces.2024.120875","url":null,"abstract":"<div><div>This work addresses the complexities of optimizing the number of stages in a distillation column, which typically lead to challenging non-linear mixed-integer optimization problems. To simplify this, we employ distributed streams, thereby eliminating discrete degrees of freedom. To avoid sophisticated initialization procedures, the optimization problem is reformulated by employing a sequence of stage-to-stage calculations, each reduced to maintaining only the MESH (mass, equilibrium, summation, heat) equations for a single stage.</div><div>Our numerical experiments show the efficiency and stability of solving the simplified optimization problem in various scenarios, including single and multiple distillation columns. For a single column scenario, we compare the accuracy of our optimization method with a full enumeration approach. Additionally, for a pressure swing flowsheet designed to separate an azeotropic mixture, we illustrate potential energy savings by optimizing a stage distribution versus using a predetermined stage distribution.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120875"},"PeriodicalIF":4.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.ces.2024.120885
Hongjian Tang, Yifan Xu, Lunbo Duan, Yufeng Duan
Elimination of neurotoxic mercury from coal-fired flue gas is imperative to the global environment. This work reclaimed waste Ti-bearing blast furnace slags (TBFS) into perovskite-type catalyst for efficient flue gas demercuration (DeHg). Through mild impregnation with Mn and Ce, the TBFS-based catalyst exhibited desirable DeHg performance at wide-range temperatures (50 ∼ 300 °C), good tolerance to varied SO2 concentrations (400 ∼ 1200 ppm), and long-term DeHg stability (30 h, > 85 % DeHg efficiency) under typical coal-fired flue gas conditions, thereby outperforming existing Mn- and Ce-containing catalysts (perovskites, spinels, and other synthetic oxides). Mn-Ce interplay was well characterized to facilitate O2 dissociation and mitigate SO2 competition by modulating the redox activity of MnCe/TBFS catalyst. DFT calculations revealed in-depth that Hg0 oxidation over MnCe/TFBS was rate-determined by O2 dissociation and significantly promoted by the activated oxygens. Our attempt herein has exemplified a feasible strategy to deal with waste slag disposal and Hg emission synergistically.
{"title":"Reclaiming Ti-bearing blast furnace slag into wide-temperature and sulfur-resistant catalyst to boost flue gas demercuration","authors":"Hongjian Tang, Yifan Xu, Lunbo Duan, Yufeng Duan","doi":"10.1016/j.ces.2024.120885","DOIUrl":"https://doi.org/10.1016/j.ces.2024.120885","url":null,"abstract":"Elimination of neurotoxic mercury from coal-fired flue gas is imperative to the global environment. This work reclaimed waste Ti-bearing blast furnace slags (TBFS) into perovskite-type catalyst for efficient flue gas demercuration (DeHg). Through mild impregnation with Mn and Ce, the TBFS-based catalyst exhibited desirable DeHg performance at wide-range temperatures (50 ∼ 300 °C), good tolerance to varied SO<sub>2</sub> concentrations (400 ∼ 1200 ppm), and long-term DeHg stability (30 h, > 85 % DeHg efficiency) under typical coal-fired flue gas conditions, thereby outperforming existing Mn- and Ce-containing catalysts (perovskites, spinels, and other synthetic oxides). Mn-Ce interplay was well characterized to facilitate O<sub>2</sub> dissociation and mitigate SO<sub>2</sub> competition by modulating the redox activity of MnCe/TBFS catalyst. DFT calculations revealed in-depth that Hg<sup>0</sup> oxidation over MnCe/TFBS was rate-determined by O<sub>2</sub> dissociation and significantly promoted by the activated oxygens. Our attempt herein has exemplified a feasible strategy to deal with waste slag disposal and Hg emission synergistically.","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"25 1","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.ces.2024.120882
Yisa Zhou , Kunyan He , Yutong Lou , Jian Xue , Haihui Wang
Membrane separation offers an efficient and energy-saving process for extracting rare helium from natural gas. Among them, mixed matrix membranes (MMMs) containing two-dimensional (2D) materials are considered potential gas separation membranes. Herein, 2D g-C3N4 nanosheets with nanoporous structure are incorporated into the polyimide (PI) matrix to prepare MMMs for efficient He separation. The incorporated g-C3N4 nanosheets generate additional gas transport and sieving channels in MMMs. As a result, the PI/g-C3N4 MMM comprising 0.5 wt% g-C3N4 nanosheets exhibits a He/CH4 selectivity of 160.4 with He permeability of 40.7 Barrer, which are 2.0 and 3.2 times higher than the pure PI membrane, respectively. Moreover, the membrane also shows good stability at elevated temperatures or a continuous 150 h long-term operation. Therefore, the remarkable gas separation performance and excellent stability make the membrane promising for gathering helium from natural gas.
{"title":"Polyimide-based mixed matrix membranes incorporated with g-C3N4 nanosheets for efficient helium enrichment","authors":"Yisa Zhou , Kunyan He , Yutong Lou , Jian Xue , Haihui Wang","doi":"10.1016/j.ces.2024.120882","DOIUrl":"10.1016/j.ces.2024.120882","url":null,"abstract":"<div><div>Membrane separation offers an efficient and energy-saving process for extracting rare helium from natural gas. Among them, mixed matrix membranes (MMMs) containing two-dimensional (2D) materials are considered potential gas separation membranes. Herein, 2D g-C<sub>3</sub>N<sub>4</sub> nanosheets with nanoporous structure are incorporated into the polyimide (PI) matrix to prepare MMMs for efficient He separation. The incorporated g-C<sub>3</sub>N<sub>4</sub> nanosheets generate additional gas transport and sieving channels in MMMs. As a result, the PI/g-C<sub>3</sub>N<sub>4</sub> MMM comprising 0.5 wt% g-C<sub>3</sub>N<sub>4</sub> nanosheets exhibits a He/CH<sub>4</sub> selectivity of 160.4 with He permeability of 40.7 Barrer, which are 2.0 and 3.2 times higher than the pure PI membrane, respectively. Moreover, the membrane also shows good stability at elevated temperatures or a continuous 150 h long-term operation. Therefore, the remarkable gas separation performance and excellent stability make the membrane promising for gathering helium from natural gas.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120882"},"PeriodicalIF":4.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.ces.2024.120883
Tian Yang , Jingwei Zhang , Heng Fang , Yundong Wang , Zhuo Chen , Jianhong Xu
This study advances the synthesis of tert-butyl hydroperoxide (TBHP) and tert-butyl peroxybenzoate (TBPB) using a continuous microreaction system, meticulously detailing kinetic behavior and optimization processes through over 1250 experimental data points. We have developed a platform capable of high-throughput kinetic experiments and precise reaction quenching, determining kinetic parameters and optimal conditions that significantly improve reaction efficiency and safety. Tailored microreaction strategies, including micro-mixers, plate microreactors, and micro-packed beds, were employed to manage exothermic reactions and enhance mass transfer for each peroxide. For TBHP, conditions were optimized to achieve a 99% conversion rate of tert-butanol and an 82% conversion of hydrogen peroxide, with product selectivity reaching 92%. For TBPB, under optimal conditions, benzoyl chloride conversion reached 99.5%, and TBHP conversion was 80%, with a product selectivity of 94%. The integration of the TBHP and TBPB synthesis processes into a single continuous-flow system demonstrates scalable, safe, and efficient production, highlighting significant potential for advancements in organic peroxide manufacturing.
{"title":"Apparent kinetics study and efficient continuous-flow synthesis of tert-butyl hydroperoxide & tert-butyl peroxybenzoate in a microreaction system","authors":"Tian Yang , Jingwei Zhang , Heng Fang , Yundong Wang , Zhuo Chen , Jianhong Xu","doi":"10.1016/j.ces.2024.120883","DOIUrl":"10.1016/j.ces.2024.120883","url":null,"abstract":"<div><div>This study advances the synthesis of <em>tert</em>-butyl hydroperoxide (TBHP) and <em>tert</em>-butyl peroxybenzoate (TBPB) using a continuous microreaction system, meticulously detailing kinetic behavior and optimization processes through over 1250 experimental data points. We have developed a platform capable of high-throughput kinetic experiments and precise reaction quenching, determining kinetic parameters and optimal conditions that significantly improve reaction efficiency and safety. Tailored microreaction strategies, including micro-mixers, plate microreactors, and micro-packed beds, were employed to manage exothermic reactions and enhance mass transfer for each peroxide. For TBHP, conditions were optimized to achieve a 99% conversion rate of <em>tert</em>-butanol and an 82% conversion of hydrogen peroxide, with product selectivity reaching 92%. For TBPB, under optimal conditions, benzoyl chloride conversion reached 99.5%, and TBHP conversion was 80%, with a product selectivity of 94%. The integration of the TBHP and TBPB synthesis processes into a single continuous-flow system demonstrates scalable, safe, and efficient production, highlighting significant potential for advancements in organic peroxide manufacturing.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120883"},"PeriodicalIF":4.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes an end-to-end model fusion feature learning method based on deep bidirectional gated recurrent unit (MCNN-DBiGRU) for fault diagnosis in industrial processes. First, a feature-aligned multi-scale feature extraction model (MCNN) is designed by analyzing the working principles of convolutional and pooling layers of convolutional neural networks. Secondly, a deep bidirectional mechanism is proposed to better extract the time series features in the process data. This mechanism makes the recurrent neural network not only present the forward processing input features from the past to the future, but also the reverse processing from the future to the past. By integrating these features, the diagnostic performance of the network model is improved. To verify that the proposed model has effective diagnostic accuracy for fault diagnosis, we conduct simulation experiments on the Tennessee-Eastman (TE) process and a chemical coking furnace, and compare with several conventional network models. In the end, not only the effectiveness of the model is proved, but it is also confirmed that the model is superior to other conventional neural networks in both diagnostic accuracy and feature robustness.
{"title":"Design of model fusion learning method based on deep bidirectional GRU neural network in fault diagnosis of industrial processes","authors":"Yaoqian Zhu , Cheng Zhang , Ridong Zhang , Furong Gao","doi":"10.1016/j.ces.2024.120884","DOIUrl":"10.1016/j.ces.2024.120884","url":null,"abstract":"<div><div>This paper proposes an end-to-end model fusion feature learning method based on deep bidirectional gated recurrent unit (MCNN-DBiGRU) for fault diagnosis in industrial processes. First, a feature-aligned multi-scale feature extraction model (MCNN) is designed by analyzing the working principles of convolutional and pooling layers of convolutional neural networks. Secondly, a deep bidirectional mechanism is proposed to better extract the time series features in the process data. This mechanism makes the recurrent neural network not only present the forward processing input features from the past to the future, but also the reverse processing from the future to the past. By integrating these features, the diagnostic performance of the network model is improved. To verify that the proposed model has effective diagnostic accuracy for fault diagnosis, we conduct simulation experiments on the Tennessee-Eastman (TE) process and a chemical coking furnace, and compare with several conventional network models. In the end, not only the effectiveness of the model is proved, but it is also confirmed that the model is superior to other conventional neural networks in both diagnostic accuracy and feature robustness.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120884"},"PeriodicalIF":4.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.ces.2024.120876
Shiqi Wang , Hui Li , Hua Li , Huiyuan Shi , Qiubai Sun , Ping Li
Due to the widespread issues of uncertainty, nonlinearity, partial actuator faults, and unmeasurable states in modern production processes, the present study developed an output feedback robust predictive fault-tolerant hybrid switching control method. The nonlinear system is described by a multiphase switching model, which largely restores the system’s nonlinear dynamics. Considering partial actuator faults, the multiphase switching model is divided into normal and fault cases. Based on this model, and to address the issue of an unmeasurable state, a robust predictive fault-tolerant hybrid switching controller is developed involving normal and fault-tolerant controllers, providing effective control in both cases. Subsequently, sufficient conditions based on linear matric inequality forms are provided, which are solved to obtain control law gains, thereby ensuring the system’s stability under both normal and fault cases. In addition, robust stability analysis and exponential stability analysis are performed, which provide the basis for the given sufficient conditions and deliver the dwell time for each phase of the system, respectively. Ultimately, the simulation using a continuous stirring reaction reactor validates the excellence of the suggested approach over traditional fault tolerance and model predictive controls, showcasing enhanced fault tolerance, reduced output and input fluctuations, and improved tracking in normal and faulty conditions.
{"title":"Output feedback robust predictive fault-tolerant hybrid switching control for a nonlinear system","authors":"Shiqi Wang , Hui Li , Hua Li , Huiyuan Shi , Qiubai Sun , Ping Li","doi":"10.1016/j.ces.2024.120876","DOIUrl":"10.1016/j.ces.2024.120876","url":null,"abstract":"<div><div>Due to the widespread issues of uncertainty, nonlinearity, partial actuator faults, and unmeasurable states in modern production processes, the present study developed an output feedback robust predictive fault-tolerant hybrid switching control method. The nonlinear system is described by a multiphase switching model, which largely restores the system’s nonlinear dynamics. Considering partial actuator faults, the multiphase switching model is divided into normal and fault cases. Based on this model, and to address the issue of an unmeasurable state, a robust predictive fault-tolerant hybrid switching controller is developed involving normal and fault-tolerant controllers, providing effective control in both cases. Subsequently, sufficient conditions based on linear matric inequality forms are provided, which are solved to obtain control law gains, thereby ensuring the system’s stability under both normal and fault cases. In addition, robust stability analysis and exponential stability analysis are performed, which provide the basis for the given sufficient conditions and deliver the dwell time for each phase of the system, respectively. Ultimately, the simulation using a continuous stirring reaction reactor validates the excellence of the suggested approach over traditional fault tolerance and model predictive controls, showcasing enhanced fault tolerance, reduced output and input fluctuations, and improved tracking in normal and faulty conditions.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120876"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.ces.2024.120871
Jiang-Wen Yan , Zi-Yue Liu , Shitao Song , Ye-Nan Bian , Ruihan Wang , Jian-Long Du
Efficient adsorption and separation of SF6 is very important for the electrical industry. In the present work, two In-MOFs (In-MOF1, In-MOF2) have been synthesized and characterized. The compounds show three-dimensional coordination networks. And the BET surface areas of them reach 859.7 cm2/g and 971.1 cm2/g, respectively. More importantly, their averaged pore sizes are mainly 5.24 Å and 5.67 Å, which are well matched with the kinetic diameter of SF6 (5.2 Å). The compounds show higher adsorption capacities of SF6 (2.66 mmol/g for In-MOF1, 2.41 mmol/g for In-MOF2) at ambient temperature and pressure. And the excellent IAST selectivities of SF6/N2 (v/v: 10:90) up to 237.8 and 235.2 at 100 kPa. Their efficient adsorption and separation performance is mainly related to the appropriate pore size and stronger host–guest interactions. DFT calculations and theoretical simulations further support the experimental results. Furthermore, dynamic breakthrough experiments show that the actual separation coefficient can reach 262.2 and 340.8, exceeding the theoretical prediction results. The results will contribute to the design of efficient MOFs adsorbents for the selective capture of SF6.
{"title":"Two In-MOFs based on pore size control strategy for highly selective separation of SF6","authors":"Jiang-Wen Yan , Zi-Yue Liu , Shitao Song , Ye-Nan Bian , Ruihan Wang , Jian-Long Du","doi":"10.1016/j.ces.2024.120871","DOIUrl":"10.1016/j.ces.2024.120871","url":null,"abstract":"<div><div>Efficient adsorption and separation of SF<sub>6</sub> is very important for the electrical industry. In the present work, two In-MOFs (In-MOF1, In-MOF2) have been synthesized and characterized. The compounds show three-dimensional coordination networks. And the BET surface areas of them reach 859.7 cm<sup>2</sup>/g and 971.1 cm<sup>2</sup>/g, respectively. More importantly, their averaged pore sizes are mainly 5.24 Å and 5.67 Å, which are well matched with the kinetic diameter of SF<sub>6</sub> (5.2 Å). The compounds show higher adsorption capacities of SF<sub>6</sub> (2.66 mmol/g for In-MOF1, 2.41 mmol/g for In-MOF2) at ambient temperature and pressure. And the excellent IAST selectivities of SF<sub>6</sub>/N<sub>2</sub> (v/v: 10:90) up to 237.8 and 235.2 at 100 kPa. Their efficient adsorption and separation performance is mainly related to the appropriate pore size and stronger host–guest interactions. DFT calculations and theoretical simulations further support the experimental results. Furthermore, dynamic breakthrough experiments show that the actual separation coefficient can reach 262.2 and 340.8, exceeding the theoretical prediction results. The results will contribute to the design of efficient MOFs adsorbents for the selective capture of SF<sub>6</sub>.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120871"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.ces.2024.120868
Anastasia Kryuchkova , Anna Ponomarets , Victoriia Suchilova, Egor Ryabchenko, Chantal Tracey, Pavel Krivoshapkin, Elena Krivoshapkina
Counterfeiting has serious economic and social consequences, prompting researchers worldwide to develop innovative and highly secure anti-counterfeiting methods, including the use of various polymer printing techniques and the integration of functional materials to create patterns with customized designs that are easy to detect and cannot be falsified. Composite inks made of silk fibroin microfibers and polyvinyl alcohol or polyethylene glycol were developed to produce patterns with the microstructures aligned in the direction of extrusion during the 3D printing process. Fibroin microfibers were obtained via high temperature treatment and used as a precursor for carbon dot synthesis. This approach allowed the microfiber structure to be maintained and be amenable to the synthesis of carbon dots doped with N-heteroatom on its surface, resulting in a material that fluoresces bright blue when irradiated at 365 nm but remains invisible in normal lighting conditions.
{"title":"3D printing of aligned silk fibroin microfibers covered with nitrogen-doped carbon dots for anti-counterfeiting","authors":"Anastasia Kryuchkova , Anna Ponomarets , Victoriia Suchilova, Egor Ryabchenko, Chantal Tracey, Pavel Krivoshapkin, Elena Krivoshapkina","doi":"10.1016/j.ces.2024.120868","DOIUrl":"10.1016/j.ces.2024.120868","url":null,"abstract":"<div><div>Counterfeiting has serious economic and social consequences, prompting researchers worldwide to develop innovative and highly secure anti-counterfeiting methods, including the use of various polymer printing techniques and the integration of functional materials to create patterns with customized designs that are easy to detect and cannot be falsified. Composite inks made of silk fibroin microfibers and polyvinyl alcohol or polyethylene glycol were developed to produce patterns with the microstructures aligned in the direction of extrusion during the 3D printing process. Fibroin microfibers were obtained via high temperature treatment and used as a precursor for carbon dot synthesis. This approach allowed the microfiber structure to be maintained and be amenable to the synthesis of carbon dots doped with N-heteroatom on its surface, resulting in a material that fluoresces bright blue when irradiated at 365 nm but remains invisible in normal lighting conditions.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120868"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.ces.2024.120872
Jiahe Fan , Yao Mu , Shuairen Qian , Bozhao Chu , Siqing Zhong , Yi Cheng
Macrocyclic polyethers have the property of selectively complexing cations with unique applications in promoting reactions involving the participation of anion-cation pairs. However, the application of macrocyclic polyethers to promote base-catalyzed nucleophilic addition of acetylene has not been reported. This research demonstrates that 15-crown-5, 18-crown-6 and 2.2.2-crypt can be used as catalytic promoters to facilitate the KOH-catalyzed vinylation of 2-pyrrolidinone. It can be used to achieve one-step synthesis of N-vinyl pyrrolidone (NVP) from acetylene with effective reduction of solvent dosage. In particular, the addition of 2.2.2-crypt leads to a 29 % increase in the yield of NVP, where the promoting effect is better than that when the solvent dosage is doubled. Spectroscopic characterization and quantum chemical computations have shown that the mechanism of macrocyclic polyethers promotion of the process consists of two aspects. On the one hand, the basicity of KOH by complexing K+ is enhanced, which in turn promotes the deprotonation process of 2-pyrrolidinone. On the other hand, the complexation of K+ enhances the nucleophilicity of N atom in the anion of 2-pyrrolidone.
{"title":"Macrocyclic polyether promoting vinylation of 2-pyrrolidone: Application and insight into mechanism","authors":"Jiahe Fan , Yao Mu , Shuairen Qian , Bozhao Chu , Siqing Zhong , Yi Cheng","doi":"10.1016/j.ces.2024.120872","DOIUrl":"10.1016/j.ces.2024.120872","url":null,"abstract":"<div><div>Macrocyclic polyethers have the property of selectively complexing cations with unique applications in promoting reactions involving the participation of anion-cation pairs. However, the application of macrocyclic polyethers to promote base-catalyzed nucleophilic addition of acetylene has not been reported. This research demonstrates that 15-crown-5, 18-crown-6 and 2.2.2-crypt can be used as catalytic promoters to facilitate the KOH-catalyzed vinylation of 2-pyrrolidinone. It can be used to achieve one-step synthesis of N-vinyl pyrrolidone (NVP) from acetylene with effective reduction of solvent dosage. In particular, the addition of 2.2.2-crypt leads to a 29 % increase in the yield of NVP, where the promoting effect is better than that when the solvent dosage is doubled. Spectroscopic characterization and quantum chemical computations have shown that the mechanism of macrocyclic polyethers promotion of the process consists of two aspects. On the one hand, the basicity of KOH by complexing K<sup>+</sup> is enhanced, which in turn promotes the deprotonation process of 2-pyrrolidinone. On the other hand, the complexation of K<sup>+</sup> enhances the nucleophilicity of N atom in the anion of 2-pyrrolidone.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120872"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.ces.2024.120869
Geunhye Won , Ye Ji Chang , Suyoung Kim , Sung Won Kim
Fine emulsified heavy-oil droplets in wastewater can be easily dispersed in aquatic system, making it challenging to remove them using sorbents. Carbon nanotube (CNT) sorbents were prepared using a m-cresol solvent to remove emulsified heavy oil in wastewater. The bead-shaped and density-controlled sorbents (diameter: 5.22 mm; density: 1169 kg/m3) facilitated efficient contact with emulsified oil and were suitable for use in a three-phase circulating fluidized bed (TPCFB). The sorbents feature a sorption capacity of 2.4 g oil/g sorbent which remained consistent for at least 10 cycles. The hydrodynamic characteristics of the TPCFB reactor (120 × 80 mm; height: 800 mm) were determined and it was found that the circulation of both liquid and solid within the TPCFB was driven by the density difference between the riser and downcomer (Δρ). The solid holdups in the downcomer (εs,d) were almost constant with gas velocity and were proportional to the amount of sorbent inventory. The optimal region for emulsified oil removal was determined to be the downcomer, where turbulent flow was generated that facilitated close contact between the particles and the liquid. The solid circulation rate (Gs) increased to a constant value with Δρ, with the maximum Gs being proportional to the sorbent inventory. The optimal conditions for wastewater treatment were determined to be a maximum εs,d of 0.03 with a Gs value above 10.0 kg/m2s and a sorbent inventory of 90 g. The oil removal rate reached a maximum of 94.8 % at Gs = 12.2 kg/m2s. Used CNT sorbent exhibited unique oil sorption characteristics of CNTs, featuring an even distribution of sulfur on the surface and a weight loss arising from loss of oil at 350–500°C.
{"title":"Oily wastewater treatment using a CNT sorbent in a three-phase circulating fluidized bed","authors":"Geunhye Won , Ye Ji Chang , Suyoung Kim , Sung Won Kim","doi":"10.1016/j.ces.2024.120869","DOIUrl":"10.1016/j.ces.2024.120869","url":null,"abstract":"<div><div>Fine emulsified heavy-oil droplets in wastewater can be easily dispersed in aquatic system, making it challenging to remove them using sorbents. Carbon nanotube (CNT) sorbents were prepared using a <em>m</em>-cresol solvent to remove emulsified heavy oil in wastewater. The bead-shaped and density-controlled sorbents (diameter: 5.22 mm; density: 1169 kg/m<sup>3</sup>) facilitated efficient contact with emulsified oil and were suitable for use in a three-phase circulating fluidized bed (TPCFB). The sorbents feature a sorption capacity of 2.4 g oil/g sorbent which remained consistent for at least 10 cycles. The hydrodynamic characteristics of the TPCFB reactor (120 × 80 mm; height: 800 mm) were determined and it was found that the circulation of both liquid and solid within the TPCFB was driven by the density difference between the riser and downcomer (Δρ). The solid holdups in the downcomer (ε<sub>s,d</sub>) were almost constant with gas velocity and were proportional to the amount of sorbent inventory. The optimal region for emulsified oil removal was determined to be the downcomer, where turbulent flow was generated that facilitated close contact between the particles and the liquid. The solid circulation rate (<em>G</em><sub>s</sub>) increased to a constant value with Δρ, with the maximum <em>G</em><sub>s</sub> being proportional to the sorbent inventory. The optimal conditions for wastewater treatment were determined to be a maximum <em>ε</em><sub>s,d</sub> of 0.03 with a <em>G</em><sub>s</sub> value above 10.0 kg/m<sup>2</sup>s and a sorbent inventory of 90 g. The oil removal rate reached a maximum of 94.8 % at <em>G</em><sub>s</sub> = 12.2 kg/m<sup>2</sup>s. Used CNT sorbent exhibited unique oil sorption characteristics of CNTs, featuring an even distribution of sulfur on the surface and a weight loss arising from loss of oil at 350–500°C.</div></div>","PeriodicalId":271,"journal":{"name":"Chemical Engineering Science","volume":"302 ","pages":"Article 120869"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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