The performance of heat transfer is a key issue for reactor design in petrochemical industry. Since the heat transfer in reactors is a complicated process and depends on multiple parameters, the evaluation of the heat...The performance of heat transfer is a key issue for reactor design in petrochemical industry. Since the heat transfer in reactors is a complicated process and depends on multiple parameters, the evaluation of the heat transfer performance is usually challenging, and few previous studies gave an overall view of heat exchange performance of different types of reactors. In this review, heat transfer coefficients of two types of petrochemical reactors, including the packed bed and the fluidized bed, were systematically analyzed and compared based on a number of reported correlations. The relationship between heat transfer coefficients and fluid flow velocity in different reactors has been well established, which clearly demonstrates the varying range of their heat transfer coefficients. Heat transfer coefficients of gas-phase packed bed can exceed 200 W/m^2·K, rather than the suggested values(17—89 W/m^2·K) mentioned in the literature. The fluidized bed shows better performance for both two-phase and three-phase beds as compared to the packed bed. Systems with liquid phase also show better heat transfer performance than other phases because of the larger heat capacity of liquid. Thus the industrial three-phase fluidized beds have the best heat transfer performance with an overall heat transfer coefficient of greater than 1 000 W/m^2·K. The heat transfer results provided by this review can afford not only new insights into the heat transfer in typical reactors, but also the basis and guidelines for reactor design and selection.展开更多
Sulfated zirconia(SZ)and two promoted 1% Mn/SZ catalysts which have been prepared via sol gel(Mn/SZ-S)and impregnation(Mn/SZ-I)methods were studied.The morphology of the catalysts was characterized by XRD,BET,NH3-TPD,...Sulfated zirconia(SZ)and two promoted 1% Mn/SZ catalysts which have been prepared via sol gel(Mn/SZ-S)and impregnation(Mn/SZ-I)methods were studied.The morphology of the catalysts was characterized by XRD,BET,NH3-TPD,ICP,SEM and FT-IR analysis.The conversion of methanol to dimethyl ether and hydrocarbons was carried out in the temperature range of 120−300℃.The Mn/SZ-S showed the highest activity due to the high surface area with suitable acidity.The optimum condition of Mn/SZ-S catalyst was investigated at 200℃ and LHSV of 0.02 h^−1 in a time range from 30 to 210 min.It was found that the total conversion decreased from 80.18% to 53.26% at 210 min.The reusability of this catalyst was studied at the optimum condition up till four cycles for 1 h.The characterization of the reused catalyst showed a significant change in the structure and surface acidity due to the blockage of the surface acid sited by carbonaceous materials.展开更多
This article describes the application of the PIMS software in formulating monthly refining production plan. Application of the PIMS software can help to solve a series of problems related with monthly plan of refinin...This article describes the application of the PIMS software in formulating monthly refining production plan. Application of the PIMS software can help to solve a series of problems related with monthly plan of refining production such as optimized selection of crude and feedstocks, optimized selection of production scale and processing scheme, identification of bottlenecks and their mitigation,optimized selection of turnaround time and optimized selection of operating regime, which have increased the economic benefits of refining enterprises. With the further development and improvement of models the PIMS software will play an increasingly important role in formulating monthly plans of refining operations and production management at refineries. This article also explores the problems existing in refinery monthly planning, and has made recommendations on developing and improving models and reporting system, enhancement of basic data acquisition, model maintenance personnel and staff training.展开更多
Hydrogen isotope separation is a challenging task due to their similar properties.Herein,based on the chemical affinity quantum sieve(CAQS)effect,the D_(2)/H_(2)separation performance of M_(2)(m-dobdc)(M=Co,Ni,Mg,Mn;m...Hydrogen isotope separation is a challenging task due to their similar properties.Herein,based on the chemical affinity quantum sieve(CAQS)effect,the D_(2)/H_(2)separation performance of M_(2)(m-dobdc)(M=Co,Ni,Mg,Mn;m-dobdc^(4-)=4,6-dioxido-1,3-benzenedicarboxylate),a series of honeycomb-shaped MOFs with high stability and abundant open metal sites,are studied by gases sorption and breakthrough experiments,in which two critical factors,gas uptake and adsorption enthalpy,are taken into consideration.Among these MOFs,Co_(2)(m-dobdc)exhibits the longest D_(2)retention time of 180 min/g(H_(2)/D_(2)/Ne:1/1/98)at 77 K because of its second-highest adsorption enthalpy(10.7 kJ/mol for H_(2)and 11.8 kJ/mol for D_(2))and the best sorption capacity(5.22 mmol/g for H_(2)and 5.49 mmol/g for D_(2))under low pressure of 1 kPa and 77 K,which make it a promising material for industrial hydrogen isotope separation.Moreover,the results indicate that H_(2)and D_(2)capacities under low pressure(about 1 kPa)dominate the final D_(2)/H_(2)separation property of MOFs.展开更多
Bubble column reactors are multiphase contacting devices used in a wide variety of industrial application. Inrtevep S. A. is working on developing technologies to convert heavy and extra-heavy crude oil using this typ...Bubble column reactors are multiphase contacting devices used in a wide variety of industrial application. Inrtevep S. A. is working on developing technologies to convert heavy and extra-heavy crude oil using this type of reactors. Volumetric gas hold up, flow pattern, average gas bubble size, average interfacial area, RTD （residence time distribution）, dispersion coefficient, Peclet number are important design parameters for a proper scale up of them. Several cold model experiments have been proposed to determine the previously mentioned parameters at atmospheric conditions, using a plexiglas bubble column reactor at pilot plant scale unit （12 cm diameter）. It was also evaluated our own design of internal trays （plates） in the reactor. Air-tap water and air-light oil systems have been used. A wide operating condition range was applied, superficial gas velocity between 0.5-10 cm/s, liquid flowrate between 15-65 I/h. Generally speaking, working without internal trays was found that gas hold up increase along the reactor and it was possible to identify heterogeneous bubble, transition and turbulent flow pattern areas for the air-light oil system. Average gas bubble size increase along the reactor at bubble regime from 2-5 mm but at turbulent regime, stay oscillating between 1-3 mm. Average interfacial area increases exponentially with superficial gas velocity at any reactor height, till 1,412 m2/m3 for the air-light oil system but, at bubble flow regime, the average interfacial area is lower than 100 m2/m3, which negatively impact the reactor performance. Internal trays in the reactor always increase gas hold up at any condition or system used. Residence time distributions curves, Peclet numbers and dispersion coefficients founded, show that this reactor with this kind of design internal trays still tends to be a complete mixing reactor under the operating conditions used.展开更多
China’s economy has maintained a steady and rapid development, the growth rate of automobiles and gasoline output and sales volume is far beyond the national economic growth rate over the same period, and much higher...China’s economy has maintained a steady and rapid development, the growth rate of automobiles and gasoline output and sales volume is far beyond the national economic growth rate over the same period, and much higher than that in developed countries. According展开更多
Currently,as the production of light crude oil is reaching its peak,the focus of the petroleum industry is shifting towards significant amount of heavy oil to meet the increasing need for energy and fuels.Heavy oil is...Currently,as the production of light crude oil is reaching its peak,the focus of the petroleum industry is shifting towards significant amount of heavy oil to meet the increasing need for energy and fuels.Heavy oil is typically categorized by its high density,great viscosity with small API gravity,high hetero-atom content and limited low boiling point fuel fraction yield compared to light oil.One approach for enhancing the flow characteristics of heavy oil before the recovery process is introducing catalysts into the reservoir.This scientific research focuses on the preparation and characterization of(10%,20%,30%)TiO_(2)@α-Fe_(2)O_(3) nanocomposite catalysts for potential catalytic applications.The study outlines the synthesis method used to create different ratios of as-prepared nanocomposites.It provides detailed characterization through various analytical techniques.The results highlight the successful formation of X%TiO_(2)@α-Fe_(2)O_(3) nanocomposites with well-defined structures and optimized properties for catalytic reactions.The study investigates the impact of this nanocomposite on the rheological characterizations of heavy crude oil,focusing on the capability of decreasing viscosity and advance flow characteristics.The experimental results demonstrate notable improvements in viscosity reduction and enhancing heavy crude oil production processes as the best results obtained by(0.5 wt%)20%TiO_(2)@α-Fe_(2)O_(3)(62.6%after 2 h at 200°C).The asphaltene and resin ratio decreased by 54.5%and 68.1%respectively.The saturated and aromatic content shows 67.56%and 15.91%respectively at the same conditions.The presence of different surfactants(non-ionic and anionic)gives a synergetic effect which reveals active participation of contact angle changing and Interfacial tension(IFT)reduction.This research contributes to the advancement of methods for upgrading heavy crude oil,offering a promising avenue for increasing efficiency and productivity in the oil industry.展开更多
This study investigates the hydraulic performance of an Ogee spillway under varying flow rate conditions,gate opening heights,and spillway widths.Numerical simulations using Flow-3D,incorporating the(k-ε)turbulence m...This study investigates the hydraulic performance of an Ogee spillway under varying flow rate conditions,gate opening heights,and spillway widths.Numerical simulations using Flow-3D,incorporating the(k-ε)turbulence model and Large Eddy Simulation(LES),were employed alongside surrogate models using MATLAB codes and LP-TAU to predict flow behavior.The analysis focused on pressure distribution,water velocity,and shear stress variations across seven sensor locations along the spillway.Results indicate that pressure distribution generally decreases with increasing flow rate but rises with greater gate opening height or spillway width.A reduction in gate opening height lowers the pressure in the initial region but increases it downstream.Two negative pressure zones were identified,one at the Ogee curve and another at the downstream sloping section,highlighting potential cavitation risks.Comparisons with experimental data confirmed a strong correlation,with minor discrepancies in specific sensors under varying conditions.The study demonstrates that numerical modeling,particularly using the(k-ε)turbulence model in Flow-3D,effectively assesses the hydraulic performance of controlled Ogee-type spillways.展开更多
The exploration of ethane(C_(2)H_(6))-selective porous materials for the direct production of polymer-grade ethylene(C_(2)H_(4))from a C_(2)H_(6)/C_(2)H_(4) mixture in a single energy-saving adsorption step is of utmo...The exploration of ethane(C_(2)H_(6))-selective porous materials for the direct production of polymer-grade ethylene(C_(2)H_(4))from a C_(2)H_(6)/C_(2)H_(4) mixture in a single energy-saving adsorption step is of utmost importance but remains a significant challenge.Thus,developing robust C_(2)H_(6)-selective adsorbents with high C_(2)H_(6) capacity and C_(2)H_(6)/C_(2)H_(4) selectivity is urgently needed for industrial applications.In this study,we have successfully designed and synthesized two novel calix[4]resorcinarene-based porous organic cages(POCs)named CPOC-501 and CPOC-502.The POCs were formed via a Schiff-base reaction involving face-directed[6+8]condensation between a bowlshaped tetratopic tetraformylcalix[4]resorcinarene and triangular tritopic amine synthons.Analysis using single crystal X-ray crystallography revealed that both cages possess large truncated octahedral cavities with a volume of approximately 6500Å3 and 12 accessible rhombic windows with a side length of approximately 10.5Å.Furthermore,the cages exhibited excellent chemical stability under neutral,acidic,and basic conditions and high Brunauer–Emmett–Teller specific surface areas of up to 2175 m^(2) g^(−1) after desolvation.Both POCs demonstrated superior adsorption capabilities for C_(2)H_(6) over C_(2)H_(4).Notably,CPOC-502 exhibited a C_(2)H_(6) capacity and C_(2)H_(6)/C_(2)H_(4) selectivity of 83 cm^(3) g^(−1) and 2.83,respectively,surpassing most of the best-performing C_(2)H_(6)-selective porous organic materials reported to date.Moreover,breakthrough experiments confirmed that both cages efficiently produced polymer-grade C_(2)H_(4)(>99.9%)directly from the C_(2)H_(6)/C_(2)H_(4) mixture,highlighting their outstanding recyclability.展开更多
In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal ...In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal receiver shape.Additionally,it establishes the ideal receiver configuration under consideration.The new work explicitly addresses the optimization of a microscale conical model,building on earlier studies by the research team that stressed the significance of reducing total heat losses.The receiver model was created using Design Modeler and treated using CFD analysis in ANSYS 2021R2 Workbench software to limit the convective mode of heat loss.Surface optimization techniques were then used,and the results were examined.To confirm the achieved results,the direct optimization method was also utilized,and it gave the same results.The internal height and the two edges on the bottom width of the receiver were found to have the greatest influence on the value of the heat transfer coefficient.Thermally,the dimensions of the optimized conical shape were found to be 384,198,114,48 and 57 mm for the internal height,total width,top width,left edge and right edge respectively.The results of this investigation showed that by reducing the heat transfer coeffi-cient by up to 90%,the tested shape’s thermal performance was significantly improved.It consequently led to an increase in overall system efficiency of around 1.3%e1.95%.展开更多
Porous organic cages(POCs)have shown great potential in many applications,and post-synthetic modification(PSM)has been confirmed to be an effective strategy to tailor their structures and related functionalities.Howev...Porous organic cages(POCs)have shown great potential in many applications,and post-synthetic modification(PSM)has been confirmed to be an effective strategy to tailor their structures and related functionalities.However,it is extremely challenging to develop a general platform for simple-to-make functional POCs for advanced applications by PSM method.Herein,we reported that octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage(HPOC-401)provides an excellent platform for post-synthetic metalation by various transition metal(TM)ions under mild conditions due to the abundance of coordination sites in its skeleton.Such metalated products(HPOC-401-TM)exhibit Brunauer-Emmett-Teller(BET)surface area up to1,456 m^(2)g^(-1),much higher than that of the pristine HPOC-401,which has a BET value of 474 m^(2)g^(-1).Moreover,the metalation and porosity increases further influence their gas capture,separation,as well as catalytic performance.For instance,HPOC-401-TM products exhibit higher CO_(2),H_(2),and C2 hydrocarbon gas uptake,as well as higher C_(2)H_(6)/C_(2)H_(4) selectivity than HPOC-401.Moreover,the HPOC-401-TM also shows better catalytic performance in the cycloaddition of CO_(2) with epoxides compared to HPOC-401.These findings uncover a simple yet effective approach for modifying the porosity characteristics of organic cages,which will undoubtedly expand their future implementations.展开更多
It is extremely challenging to construct three-dimensional(3D)crystalline covalent organic frameworks(COFs)with flexible building blocks and to further explore their tunable or adaptive characteristics due to crystall...It is extremely challenging to construct three-dimensional(3D)crystalline covalent organic frameworks(COFs)with flexible building blocks and to further explore their tunable or adaptive characteristics due to crystallization and structure determination difficulties.Herein,we constructed three crystalline isostructural 3D-OC-COFs based on a newly synthesized flexible organic cage(6NH_(2)-OC.4HCl)through a novel in situ acid–base neutralization strategy.展开更多
The unique adsorption performance of metal-organic frameworks(MOFs) indicates a new direction for gas separation and purification. The low-temperature distillation, as a traditional technique for hydrogen isotope sepa...The unique adsorption performance of metal-organic frameworks(MOFs) indicates a new direction for gas separation and purification. The low-temperature distillation, as a traditional technique for hydrogen isotope separation, is limited as it is a high energy-and cost-intensive process. Instead of utilizing such a conventional separation route, we use ordered microporous frameworks based on a physical adsorption mechanism to solve the challenge of hydrogen isotope separation. Herein we analyze M-MOF-74(M=Co, Ni, Mg, Zn), featuring a hexagonal channel about 11 ? and high density of open metal sites, for their ability to separate and purify deuterium from the hydrogen isotope mixture by dynamic column breakthrough experiments. Our results show that the combination of the strength of binding sites, density of coordinatively unsaturated metal sites and hydrogen isotope adsorption capacity of materials renders Co-MOF-74 as an optimal adsorbent for the capture of deuterium from hydrogen isotope mixtures in a simulated industrial process.展开更多
文摘The performance of heat transfer is a key issue for reactor design in petrochemical industry. Since the heat transfer in reactors is a complicated process and depends on multiple parameters, the evaluation of the heat transfer performance is usually challenging, and few previous studies gave an overall view of heat exchange performance of different types of reactors. In this review, heat transfer coefficients of two types of petrochemical reactors, including the packed bed and the fluidized bed, were systematically analyzed and compared based on a number of reported correlations. The relationship between heat transfer coefficients and fluid flow velocity in different reactors has been well established, which clearly demonstrates the varying range of their heat transfer coefficients. Heat transfer coefficients of gas-phase packed bed can exceed 200 W/m^2·K, rather than the suggested values(17—89 W/m^2·K) mentioned in the literature. The fluidized bed shows better performance for both two-phase and three-phase beds as compared to the packed bed. Systems with liquid phase also show better heat transfer performance than other phases because of the larger heat capacity of liquid. Thus the industrial three-phase fluidized beds have the best heat transfer performance with an overall heat transfer coefficient of greater than 1 000 W/m^2·K. The heat transfer results provided by this review can afford not only new insights into the heat transfer in typical reactors, but also the basis and guidelines for reactor design and selection.
文摘Sulfated zirconia(SZ)and two promoted 1% Mn/SZ catalysts which have been prepared via sol gel(Mn/SZ-S)and impregnation(Mn/SZ-I)methods were studied.The morphology of the catalysts was characterized by XRD,BET,NH3-TPD,ICP,SEM and FT-IR analysis.The conversion of methanol to dimethyl ether and hydrocarbons was carried out in the temperature range of 120−300℃.The Mn/SZ-S showed the highest activity due to the high surface area with suitable acidity.The optimum condition of Mn/SZ-S catalyst was investigated at 200℃ and LHSV of 0.02 h^−1 in a time range from 30 to 210 min.It was found that the total conversion decreased from 80.18% to 53.26% at 210 min.The reusability of this catalyst was studied at the optimum condition up till four cycles for 1 h.The characterization of the reused catalyst showed a significant change in the structure and surface acidity due to the blockage of the surface acid sited by carbonaceous materials.
文摘This article describes the application of the PIMS software in formulating monthly refining production plan. Application of the PIMS software can help to solve a series of problems related with monthly plan of refining production such as optimized selection of crude and feedstocks, optimized selection of production scale and processing scheme, identification of bottlenecks and their mitigation,optimized selection of turnaround time and optimized selection of operating regime, which have increased the economic benefits of refining enterprises. With the further development and improvement of models the PIMS software will play an increasingly important role in formulating monthly plans of refining operations and production management at refineries. This article also explores the problems existing in refinery monthly planning, and has made recommendations on developing and improving models and reporting system, enhancement of basic data acquisition, model maintenance personnel and staff training.
基金financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB20000000)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.QYZDB-SSW-SLH019)the National Natural Science Foundation of China(Nos.21771177,51603206 and 21203117).
文摘Hydrogen isotope separation is a challenging task due to their similar properties.Herein,based on the chemical affinity quantum sieve(CAQS)effect,the D_(2)/H_(2)separation performance of M_(2)(m-dobdc)(M=Co,Ni,Mg,Mn;m-dobdc^(4-)=4,6-dioxido-1,3-benzenedicarboxylate),a series of honeycomb-shaped MOFs with high stability and abundant open metal sites,are studied by gases sorption and breakthrough experiments,in which two critical factors,gas uptake and adsorption enthalpy,are taken into consideration.Among these MOFs,Co_(2)(m-dobdc)exhibits the longest D_(2)retention time of 180 min/g(H_(2)/D_(2)/Ne:1/1/98)at 77 K because of its second-highest adsorption enthalpy(10.7 kJ/mol for H_(2)and 11.8 kJ/mol for D_(2))and the best sorption capacity(5.22 mmol/g for H_(2)and 5.49 mmol/g for D_(2))under low pressure of 1 kPa and 77 K,which make it a promising material for industrial hydrogen isotope separation.Moreover,the results indicate that H_(2)and D_(2)capacities under low pressure(about 1 kPa)dominate the final D_(2)/H_(2)separation property of MOFs.
文摘Bubble column reactors are multiphase contacting devices used in a wide variety of industrial application. Inrtevep S. A. is working on developing technologies to convert heavy and extra-heavy crude oil using this type of reactors. Volumetric gas hold up, flow pattern, average gas bubble size, average interfacial area, RTD （residence time distribution）, dispersion coefficient, Peclet number are important design parameters for a proper scale up of them. Several cold model experiments have been proposed to determine the previously mentioned parameters at atmospheric conditions, using a plexiglas bubble column reactor at pilot plant scale unit （12 cm diameter）. It was also evaluated our own design of internal trays （plates） in the reactor. Air-tap water and air-light oil systems have been used. A wide operating condition range was applied, superficial gas velocity between 0.5-10 cm/s, liquid flowrate between 15-65 I/h. Generally speaking, working without internal trays was found that gas hold up increase along the reactor and it was possible to identify heterogeneous bubble, transition and turbulent flow pattern areas for the air-light oil system. Average gas bubble size increase along the reactor at bubble regime from 2-5 mm but at turbulent regime, stay oscillating between 1-3 mm. Average interfacial area increases exponentially with superficial gas velocity at any reactor height, till 1,412 m2/m3 for the air-light oil system but, at bubble flow regime, the average interfacial area is lower than 100 m2/m3, which negatively impact the reactor performance. Internal trays in the reactor always increase gas hold up at any condition or system used. Residence time distributions curves, Peclet numbers and dispersion coefficients founded, show that this reactor with this kind of design internal trays still tends to be a complete mixing reactor under the operating conditions used.
文摘China’s economy has maintained a steady and rapid development, the growth rate of automobiles and gasoline output and sales volume is far beyond the national economic growth rate over the same period, and much higher than that in developed countries. According
基金[Egyptian Petroleum Research Institute] for their invaluable support and assistance in conducting this research
文摘Currently,as the production of light crude oil is reaching its peak,the focus of the petroleum industry is shifting towards significant amount of heavy oil to meet the increasing need for energy and fuels.Heavy oil is typically categorized by its high density,great viscosity with small API gravity,high hetero-atom content and limited low boiling point fuel fraction yield compared to light oil.One approach for enhancing the flow characteristics of heavy oil before the recovery process is introducing catalysts into the reservoir.This scientific research focuses on the preparation and characterization of(10%,20%,30%)TiO_(2)@α-Fe_(2)O_(3) nanocomposite catalysts for potential catalytic applications.The study outlines the synthesis method used to create different ratios of as-prepared nanocomposites.It provides detailed characterization through various analytical techniques.The results highlight the successful formation of X%TiO_(2)@α-Fe_(2)O_(3) nanocomposites with well-defined structures and optimized properties for catalytic reactions.The study investigates the impact of this nanocomposite on the rheological characterizations of heavy crude oil,focusing on the capability of decreasing viscosity and advance flow characteristics.The experimental results demonstrate notable improvements in viscosity reduction and enhancing heavy crude oil production processes as the best results obtained by(0.5 wt%)20%TiO_(2)@α-Fe_(2)O_(3)(62.6%after 2 h at 200°C).The asphaltene and resin ratio decreased by 54.5%and 68.1%respectively.The saturated and aromatic content shows 67.56%and 15.91%respectively at the same conditions.The presence of different surfactants(non-ionic and anionic)gives a synergetic effect which reveals active participation of contact angle changing and Interfacial tension(IFT)reduction.This research contributes to the advancement of methods for upgrading heavy crude oil,offering a promising avenue for increasing efficiency and productivity in the oil industry.
文摘This study investigates the hydraulic performance of an Ogee spillway under varying flow rate conditions,gate opening heights,and spillway widths.Numerical simulations using Flow-3D,incorporating the(k-ε)turbulence model and Large Eddy Simulation(LES),were employed alongside surrogate models using MATLAB codes and LP-TAU to predict flow behavior.The analysis focused on pressure distribution,water velocity,and shear stress variations across seven sensor locations along the spillway.Results indicate that pressure distribution generally decreases with increasing flow rate but rises with greater gate opening height or spillway width.A reduction in gate opening height lowers the pressure in the initial region but increases it downstream.Two negative pressure zones were identified,one at the Ogee curve and another at the downstream sloping section,highlighting potential cavitation risks.Comparisons with experimental data confirmed a strong correlation,with minor discrepancies in specific sensors under varying conditions.The study demonstrates that numerical modeling,particularly using the(k-ε)turbulence model in Flow-3D,effectively assesses the hydraulic performance of controlled Ogee-type spillways.
基金financially supported by the National Nature Science Foundation of China(grant nos.22071244 and 22275191)the Youth Innovation Promotion Association CAS(grant no.2022305)the Natural Science Foundation of Fujian Province of China(grant nos.2022J01503,2020J05087,and 2022I0037).
文摘The exploration of ethane(C_(2)H_(6))-selective porous materials for the direct production of polymer-grade ethylene(C_(2)H_(4))from a C_(2)H_(6)/C_(2)H_(4) mixture in a single energy-saving adsorption step is of utmost importance but remains a significant challenge.Thus,developing robust C_(2)H_(6)-selective adsorbents with high C_(2)H_(6) capacity and C_(2)H_(6)/C_(2)H_(4) selectivity is urgently needed for industrial applications.In this study,we have successfully designed and synthesized two novel calix[4]resorcinarene-based porous organic cages(POCs)named CPOC-501 and CPOC-502.The POCs were formed via a Schiff-base reaction involving face-directed[6+8]condensation between a bowlshaped tetratopic tetraformylcalix[4]resorcinarene and triangular tritopic amine synthons.Analysis using single crystal X-ray crystallography revealed that both cages possess large truncated octahedral cavities with a volume of approximately 6500Å3 and 12 accessible rhombic windows with a side length of approximately 10.5Å.Furthermore,the cages exhibited excellent chemical stability under neutral,acidic,and basic conditions and high Brunauer–Emmett–Teller specific surface areas of up to 2175 m^(2) g^(−1) after desolvation.Both POCs demonstrated superior adsorption capabilities for C_(2)H_(6) over C_(2)H_(4).Notably,CPOC-502 exhibited a C_(2)H_(6) capacity and C_(2)H_(6)/C_(2)H_(4) selectivity of 83 cm^(3) g^(−1) and 2.83,respectively,surpassing most of the best-performing C_(2)H_(6)-selective porous organic materials reported to date.Moreover,breakthrough experiments confirmed that both cages efficiently produced polymer-grade C_(2)H_(4)(>99.9%)directly from the C_(2)H_(6)/C_(2)H_(4) mixture,highlighting their outstanding recyclability.
文摘In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal receiver shape.Additionally,it establishes the ideal receiver configuration under consideration.The new work explicitly addresses the optimization of a microscale conical model,building on earlier studies by the research team that stressed the significance of reducing total heat losses.The receiver model was created using Design Modeler and treated using CFD analysis in ANSYS 2021R2 Workbench software to limit the convective mode of heat loss.Surface optimization techniques were then used,and the results were examined.To confirm the achieved results,the direct optimization method was also utilized,and it gave the same results.The internal height and the two edges on the bottom width of the receiver were found to have the greatest influence on the value of the heat transfer coefficient.Thermally,the dimensions of the optimized conical shape were found to be 384,198,114,48 and 57 mm for the internal height,total width,top width,left edge and right edge respectively.The results of this investigation showed that by reducing the heat transfer coeffi-cient by up to 90%,the tested shape’s thermal performance was significantly improved.It consequently led to an increase in overall system efficiency of around 1.3%e1.95%.
基金supported by the National Natural Science Foundation of China(22071244)the Youth Innovation Promotion Association CAS(2022305)+1 种基金the Natural Science Foundation of Fujian Province of China(2022J01503,2020J05087)the China Postdoctoral Science Foundation(2020M671954)。
文摘Porous organic cages(POCs)have shown great potential in many applications,and post-synthetic modification(PSM)has been confirmed to be an effective strategy to tailor their structures and related functionalities.However,it is extremely challenging to develop a general platform for simple-to-make functional POCs for advanced applications by PSM method.Herein,we reported that octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage(HPOC-401)provides an excellent platform for post-synthetic metalation by various transition metal(TM)ions under mild conditions due to the abundance of coordination sites in its skeleton.Such metalated products(HPOC-401-TM)exhibit Brunauer-Emmett-Teller(BET)surface area up to1,456 m^(2)g^(-1),much higher than that of the pristine HPOC-401,which has a BET value of 474 m^(2)g^(-1).Moreover,the metalation and porosity increases further influence their gas capture,separation,as well as catalytic performance.For instance,HPOC-401-TM products exhibit higher CO_(2),H_(2),and C2 hydrocarbon gas uptake,as well as higher C_(2)H_(6)/C_(2)H_(4) selectivity than HPOC-401.Moreover,the HPOC-401-TM also shows better catalytic performance in the cycloaddition of CO_(2) with epoxides compared to HPOC-401.These findings uncover a simple yet effective approach for modifying the porosity characteristics of organic cages,which will undoubtedly expand their future implementations.
基金supported by the National Key R&D Program of China(no.2017YFA0700102)the National Natural Science Foundation of China(nos.22071244 and 21771177)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(no.QYZDB-SSWSLH019)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(no.2021ZZ106)the Advanced Energy Science and Technology Guangdong Laboratory.
文摘It is extremely challenging to construct three-dimensional(3D)crystalline covalent organic frameworks(COFs)with flexible building blocks and to further explore their tunable or adaptive characteristics due to crystallization and structure determination difficulties.Herein,we constructed three crystalline isostructural 3D-OC-COFs based on a newly synthesized flexible organic cage(6NH_(2)-OC.4HCl)through a novel in situ acid–base neutralization strategy.
基金supported by the National Natural Science Foundation of China (21771177)the Strategic Priority Research Program of Chinese Academy of Sciences (XDB20000000)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (QYZDB-SSW-SLH019)。
文摘The unique adsorption performance of metal-organic frameworks(MOFs) indicates a new direction for gas separation and purification. The low-temperature distillation, as a traditional technique for hydrogen isotope separation, is limited as it is a high energy-and cost-intensive process. Instead of utilizing such a conventional separation route, we use ordered microporous frameworks based on a physical adsorption mechanism to solve the challenge of hydrogen isotope separation. Herein we analyze M-MOF-74(M=Co, Ni, Mg, Zn), featuring a hexagonal channel about 11 ? and high density of open metal sites, for their ability to separate and purify deuterium from the hydrogen isotope mixture by dynamic column breakthrough experiments. Our results show that the combination of the strength of binding sites, density of coordinatively unsaturated metal sites and hydrogen isotope adsorption capacity of materials renders Co-MOF-74 as an optimal adsorbent for the capture of deuterium from hydrogen isotope mixtures in a simulated industrial process.
