本文采用Ffowcs Williams and Hawkings(FW-H)声类比法对圆柱-翼型干涉流场在来流翼弦雷诺数Rec=4.8×105条件下的噪声指向性分布规律进行了研究。研究了不同精度的湍流求解方法RANS和DDES对流场中速度分布以及非定常速度脉动的预...本文采用Ffowcs Williams and Hawkings(FW-H)声类比法对圆柱-翼型干涉流场在来流翼弦雷诺数Rec=4.8×105条件下的噪声指向性分布规律进行了研究。研究了不同精度的湍流求解方法RANS和DDES对流场中速度分布以及非定常速度脉动的预测准确性,进一步对流场中不同位置的声压级进行预测。通过与实验数据对比,验证并且评估FLUENT中FW-H气动噪声模型的精度,最后对圆柱翼型间的不同距离和来流速度对各个噪声监测点的总声压级影响进行了研究,讨论其对噪声的影响规律及噪声的指向性分布规律。本文研究结果有助于验证气动模型准确性,对于下一步采用该模型预测其它复杂结构产生的气动噪声问题具有指导意义。展开更多
Neutron and gamma ray pulse signal discrimination technology is an essential part of many modern scientific fields,such as biology,geology,radiation imaging,and nuclear medicine.Neutrons are always accompanied by gamm...Neutron and gamma ray pulse signal discrimination technology is an essential part of many modern scientific fields,such as biology,geology,radiation imaging,and nuclear medicine.Neutrons are always accompanied by gamma rays due to their unique penetration characteristic;thus,the development of n-γdiscrimination methods is especially crucial.In the present study,a novel n-γdiscrimination method is proposed that implements a pulse-coupled neural network for n-γdiscrimination.In addition,experiments were conducted on the pulse signals detected by an EJ299-33 plastic scintillator,which is especially suitable for n-γdiscrimination.The proposed method was compared to three other discrimination methods,including the back-propagation neural network(BPNN),the fractal spectrum method,and the charge comparison method,with respect to two aspects:(i)the figure of merit(FoM)and(ii)discrimination time.The experimental results showed that the pulse-coupled neural network(PCNN)has a 26.49%improvement in FoM-value compared to the charge comparison method,a72.80%improvement compared to the BPNN,a 66.24%improvement compared to the fractal spectrum method,and the second-fastest discrimination time of 2.22 s.In conclusion,the PCNN treats the input signal as a whole for analysis and processing,imparting it with an excellent antinoise effect and the ability to process the dynamic information contained in a pulse signal.展开更多
In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,r...In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,radiation pulse signals were pre-processed using a Fourier filter to reduce the original noise in the signals,whereas in the second group,the original noise was left untouched to simulate an extremely high-noise scenario.For each part,artificial Gaussian noise with different intensity levels was added to the signals prior to the discrimination process.In the aforementioned conditions,the performance of the PCNN was evaluated and compared with five other commonly used methods of n-γdiscrimination:(1)zero crossing,(2)charge comparison,(3)vector projection,(4)falling edge percentage slope,and(5)frequency gradient analysis.The experimental results showed that the PCNN method significantly outperforms other methods with outstanding FoM-value at all noise levels.Furthermore,the fluctuations in FoM-value of PCNN were significantly better than those obtained via other methods at most noise levels and only slightly worse than those obtained via the charge comparison and zerocrossing methods under extreme noise conditions.Additionally,the changing patterns and fluctuations of the FoMvalue were evaluated under different noise conditions.Hence,based on the results,the parameter selection strategy of the PCNN was presented.In conclusion,the PCNN method is suitable for use in high-noise application scenarios for n-γdiscrimination because of its stability and remarkable discrimination performance.It does not rely on strict parameter settings and can realize satisfactory performance over a wide parameter range.展开更多
Digital pulse processing has developed rapidly during recent years.Moreover,it has been widely applied in many fields.In this study,we introduce a digital pulse processing method for 2πa and 2πb emitter measurement....Digital pulse processing has developed rapidly during recent years.Moreover,it has been widely applied in many fields.In this study,we introduce a digital pulse processing method for 2πa and 2πb emitter measurement.Our digital pulse processing method for 2πa and 2πb emitter measurement is comprised of a field-programmable gate-array-based acquisition card and a pulse-height analysis routine.We established two channels(one for the a emitter and one for the b emitter) on an acquisition board using an analog-to-digital converter with a 16-bit resolution at a speed of 100 million samples per second.In this study,we used captured and stored data to analyze emission rate counts and spectrums.The method we established takes into account noise cancelation,dead-time correction,background subtraction,and zero-energy extrapolation.We carefully designed control procedures in order to simplify pulse-width fitting and threshold-level setting.We transmitted data and commands through a universal serial bus between the acquisition board and the computer.The results of our tests prove that our method performs well in pulse reconstruction fidelity and amplitude measurement accuracy.Compared with the current standard method for measuring 2πa and 2πb emission rates,our system demonstrates excellent precision in emission rate counting.展开更多
Neutrons have been extensively used in many fields,such as nuclear physics,biology,geology,medical science,and national defense,owing to their unique penetration characteristics.Gamma rays are usually accompanied by t...Neutrons have been extensively used in many fields,such as nuclear physics,biology,geology,medical science,and national defense,owing to their unique penetration characteristics.Gamma rays are usually accompanied by the detection of neutrons.The capability to discriminate neutrons from gamma rays is important for evaluating plastic scintillator neutron detectors because similar pulse shapes are generated from both forms of radiation in the detection system.The pulse signals measured by plastic scintillators contain noise,which decreases the accuracy of n-y discrimination.To improve the performance of n-y discrimination,the noise of the pulse signals should be filtered before the n-y discrimination process.In this study,the influences of the Fourier transform,wavelet transform,moving-average filter,and Kalman algorithm on the charge comparison method,fractal spectrum method,and back-propagation neural network methods were studied.It was found that the Fourier transform filtering algorithm exhibits better adaptability to the charge comparison method than others,with an increasing accuracy of 6.87%compared to that without the filtering process.Meanwhile,the Kalman filter offers an improvement of 3.04%over the fractal spectrum method,and the adaptability of the moving-average filter in backpropagation neural network discrimination is better than that in other methods,with an increase in 8.48%.The Kalman filtering algorithm has a significant impact on the peak value of the pulse,reaching 4.49%,and it has an insignificant impact on the energy resolution of the spectrum measurement after discrimination.展开更多
This study proposes a ladder gradient method for neutron and gamma-ray discrimination.The proposed method exhibited state-of-the-art performance with low time consumption,which incorporates two parts:information extra...This study proposes a ladder gradient method for neutron and gamma-ray discrimination.The proposed method exhibited state-of-the-art performance with low time consumption,which incorporates two parts:information extraction and discrimination factor calculation.A quasi-continuous spiking cortical model was proposed to extract information from the radiation pulse signals,thus generating an ignition map corresponding to each pulse signal.The ignition map can be used to calculate the discrimination factor.A ladder gradient calculation was introduced to obtain a discrimination factor with low computational complexity.The proposed method was compared with five other discrimination methods to evaluate its robustness and efficacy.Furthermore,the filter adaptability of the pulse-coupled neural network and ladder gradient methods was investigated.Possible reasons for adapting the conditions with different discrimination methods and filters were analyzed.Experiments were conducted in 20 filtering situations with 11 types of filters to determine the most suitable filters for discrimination methods.The experimental results revealed that the three most adaptive filters of the pulse-coupled neural networks and ladder gradient methods are the wavelet,elliptic,and median filters and the elliptic,moving average,and wavelet filters,respectively.展开更多
A transition edge sensor(TES)is extremely sensitive to changes in temperature,and combined with a high-Z metal of a certain thickness,it can realize high-energy resolution measurements of particles such as X-rays.X-ra...A transition edge sensor(TES)is extremely sensitive to changes in temperature,and combined with a high-Z metal of a certain thickness,it can realize high-energy resolution measurements of particles such as X-rays.X-rays with energies below 10 keV have a weak penetrating ability,hence,only gold or bismuth of a few micrometers in thickness can guarantee a quantum efficiency higher than 70%.Therefore,the entire structure of the TES X-ray detector in this energy range can be realized using a microfabrication process.However,for X-rays or γ-rays from 10 keV to 200 keV,submillimeter absorber layers are required,which cannot be realized using the microfabrication process.This paper first briefly introduces a set of TES X-ray detectors and their auxiliary systems,and then focuses on the introduction of the TES γ-ray detector with an absorber based on a submillimeter lead-tin alloy sphere.The detector achieved a quantum efficiency above 70% near 100 keV and an energy resolution of approximately 161.5 eV at 59.5 keV.展开更多
The marine biological sonar system evolved in the struggle of nature is far superior to the current artificial sonar. Therefore, the development of bionic underwater concealed detection is of great strategic significa...The marine biological sonar system evolved in the struggle of nature is far superior to the current artificial sonar. Therefore, the development of bionic underwater concealed detection is of great strategic significance to the military and economy. In this paper, a generative adversarial network(GAN) is trained based on the dolphin vocal sound dataset we constructed, which can achieve unsupervised generation of dolphin vocal sounds with global consistency. Through the analysis of the generated audio samples and the real audio samples in the time domain and the frequency domain, it can be proven that the generated audio samples are close to the real audio samples,which meets the requirements of bionic underwater concealed detection.展开更多
CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should...CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should be relied on its environmental impact.In this work,life cycle assessment model evaluates the environmental performance of CO_(2)conversion by photocatalytic reaction process with two different catalysts(NiAl-LDH and Co-ZIF-9).Six impact categories considered in this analysis,including climate change,acidification potential,depletion of abiotic resources,eutrophication potential,ozone layer depletion potential,and photochemical oxidation potential.Results indicated that CO_(2)conversion with Co-ZIF-9 photocatalyst has a better environmental impact than the NiAl-LDH photocatalyst route.Moreover,the Co-ZIF-9 catalyst scenario also has a lower total environmental burden than the conventional CO production route.Sensitivity analysis shows that recycle performance of the catalyst is highly sensitive to the production process in two scenarios.This study could provide a framework for robust decisions in CO_(2)conversion by photocatalytic reaction,which is useful for policymakers to decide the feasibility of industrialization.展开更多
In the semiconductor industry,recovering and capturing SF_(6)gas from the SF_(6)/N_(2)gas mixture has significant environmental and economic benefits.In this work,two Ni-based metal-organic frameworks(MOFs),Ni(i-na)(b...In the semiconductor industry,recovering and capturing SF_(6)gas from the SF_(6)/N_(2)gas mixture has significant environmental and economic benefits.In this work,two Ni-based metal-organic frameworks(MOFs),Ni(i-na)(bdc)_(0.5)(ina=isonicotinic acid,bdc=terephthalic acid)and methyl-functionalized Ni(3-min)(bdc)_(0.5)(3-min=3-methylisonicotinic acid),are constructed for SF_(6)capture.Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)are both highly stable nine-connected porous materials.The pore sizes of these two materials are similar,but the pore environments are different,which has a bearing on the performance of SF_(6)/N_(2)separations.Ni(3-min)(bdc)0.s exhibits higher SF_(6)adsorption capacity(50.5 cm^(3)g^(-1))and IAST(ideal adsorbed solution theory)SF_(6)/N_(2)selectivity(91)owing to its smaller window diameter and suitable pore chemistry.Theoretical calculations indicate that the SF_(6)and N_(2)molecules interact with the framework at different cages,which reduces their competition for adsorption sites.The remarkable separation performance of Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)is further verified by dynamic breakthrough experiments.Thus,these two adsorbents have the potential to be utilized in industrial applications due to their excellent structural stability and recyclability.展开更多
Comprehensive Summary Carbon dioxide(CO_(2))capture is one of the most important aspects of reducing global warming.In terms of CO_(2)capture,metal-organic frameworks(MOFs)have several advantages.However,it isn't ...Comprehensive Summary Carbon dioxide(CO_(2))capture is one of the most important aspects of reducing global warming.In terms of CO_(2)capture,metal-organic frameworks(MOFs)have several advantages.However,it isn't easy to shape MOFs while maintaining their performance.Herein,we describe the development of a pellet-shaped ultramicroporous MOF,Ni(3-ain)2(3-ain=3-aminoinoisonicotinic acid),that is capable of selectively adsorbing CO_(2).Polyvinyl butyral(PVB)is used as a binder during the production of Ni(3-ain)2 MOF pellets.The adequately shaped material can maintain its crystallinity and exhibit a high CO_(2)adsorption capacity(3.73 mmol·g^(-1))at ambient conditions,which is significantly greater than those obtained for N_(2)(0.63 mmol·g^(-1))and CO(0.90 mmol·g^(-1)).Consequently,this material displays high IAST selectivities for CO_(2)/N_(2)(26.3,15/85,V/V)and CO_(2)/CO(19.2,1/99,V/V).According to the theoretical calculations,Ni(3-ain)2 preferentially adsorbs CO_(2)molecules over N_(2)molecules and CO molecules.The results of experiments on dynamic breakthrough have demonstrated that Ni(3-ain)2 pellets are capable of effectively separating CO_(2)/N_(2)or CO_(2)/CO mixtures under conditions of dynamic flow.Furthermore,the structured MOF materials can be synthesized in one step at kilogram scale.This work provides an avenue for the shaping of MOFs for potential industrial applications in the future.展开更多
文摘本文采用Ffowcs Williams and Hawkings(FW-H)声类比法对圆柱-翼型干涉流场在来流翼弦雷诺数Rec=4.8×105条件下的噪声指向性分布规律进行了研究。研究了不同精度的湍流求解方法RANS和DDES对流场中速度分布以及非定常速度脉动的预测准确性,进一步对流场中不同位置的声压级进行预测。通过与实验数据对比,验证并且评估FLUENT中FW-H气动噪声模型的精度,最后对圆柱翼型间的不同距离和来流速度对各个噪声监测点的总声压级影响进行了研究,讨论其对噪声的影响规律及噪声的指向性分布规律。本文研究结果有助于验证气动模型准确性,对于下一步采用该模型预测其它复杂结构产生的气动噪声问题具有指导意义。
基金supported by the Key Science and Technology projects of Leshan(No.19SZD117)the Sichuan Science and Technology Program(No.2021JDRC0108)。
文摘Neutron and gamma ray pulse signal discrimination technology is an essential part of many modern scientific fields,such as biology,geology,radiation imaging,and nuclear medicine.Neutrons are always accompanied by gamma rays due to their unique penetration characteristic;thus,the development of n-γdiscrimination methods is especially crucial.In the present study,a novel n-γdiscrimination method is proposed that implements a pulse-coupled neural network for n-γdiscrimination.In addition,experiments were conducted on the pulse signals detected by an EJ299-33 plastic scintillator,which is especially suitable for n-γdiscrimination.The proposed method was compared to three other discrimination methods,including the back-propagation neural network(BPNN),the fractal spectrum method,and the charge comparison method,with respect to two aspects:(i)the figure of merit(FoM)and(ii)discrimination time.The experimental results showed that the pulse-coupled neural network(PCNN)has a 26.49%improvement in FoM-value compared to the charge comparison method,a72.80%improvement compared to the BPNN,a 66.24%improvement compared to the fractal spectrum method,and the second-fastest discrimination time of 2.22 s.In conclusion,the PCNN treats the input signal as a whole for analysis and processing,imparting it with an excellent antinoise effect and the ability to process the dynamic information contained in a pulse signal.
基金supported by the National Natural Science Foundation of China(Nos.4210040255,U19A2086)the Sichuan Science and Technology Program(No.2021JDRC0108)。
文摘In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,radiation pulse signals were pre-processed using a Fourier filter to reduce the original noise in the signals,whereas in the second group,the original noise was left untouched to simulate an extremely high-noise scenario.For each part,artificial Gaussian noise with different intensity levels was added to the signals prior to the discrimination process.In the aforementioned conditions,the performance of the PCNN was evaluated and compared with five other commonly used methods of n-γdiscrimination:(1)zero crossing,(2)charge comparison,(3)vector projection,(4)falling edge percentage slope,and(5)frequency gradient analysis.The experimental results showed that the PCNN method significantly outperforms other methods with outstanding FoM-value at all noise levels.Furthermore,the fluctuations in FoM-value of PCNN were significantly better than those obtained via other methods at most noise levels and only slightly worse than those obtained via the charge comparison and zerocrossing methods under extreme noise conditions.Additionally,the changing patterns and fluctuations of the FoMvalue were evaluated under different noise conditions.Hence,based on the results,the parameter selection strategy of the PCNN was presented.In conclusion,the PCNN method is suitable for use in high-noise application scenarios for n-γdiscrimination because of its stability and remarkable discrimination performance.It does not rely on strict parameter settings and can realize satisfactory performance over a wide parameter range.
文摘Digital pulse processing has developed rapidly during recent years.Moreover,it has been widely applied in many fields.In this study,we introduce a digital pulse processing method for 2πa and 2πb emitter measurement.Our digital pulse processing method for 2πa and 2πb emitter measurement is comprised of a field-programmable gate-array-based acquisition card and a pulse-height analysis routine.We established two channels(one for the a emitter and one for the b emitter) on an acquisition board using an analog-to-digital converter with a 16-bit resolution at a speed of 100 million samples per second.In this study,we used captured and stored data to analyze emission rate counts and spectrums.The method we established takes into account noise cancelation,dead-time correction,background subtraction,and zero-energy extrapolation.We carefully designed control procedures in order to simplify pulse-width fitting and threshold-level setting.We transmitted data and commands through a universal serial bus between the acquisition board and the computer.The results of our tests prove that our method performs well in pulse reconstruction fidelity and amplitude measurement accuracy.Compared with the current standard method for measuring 2πa and 2πb emission rates,our system demonstrates excellent precision in emission rate counting.
基金supported by the Key Natural Science Projects of the Sichuan Education Department(No.18ZA0067)the Key Science and Technology Projects of Leshan(No.19SZD117)。
文摘Neutrons have been extensively used in many fields,such as nuclear physics,biology,geology,medical science,and national defense,owing to their unique penetration characteristics.Gamma rays are usually accompanied by the detection of neutrons.The capability to discriminate neutrons from gamma rays is important for evaluating plastic scintillator neutron detectors because similar pulse shapes are generated from both forms of radiation in the detection system.The pulse signals measured by plastic scintillators contain noise,which decreases the accuracy of n-y discrimination.To improve the performance of n-y discrimination,the noise of the pulse signals should be filtered before the n-y discrimination process.In this study,the influences of the Fourier transform,wavelet transform,moving-average filter,and Kalman algorithm on the charge comparison method,fractal spectrum method,and back-propagation neural network methods were studied.It was found that the Fourier transform filtering algorithm exhibits better adaptability to the charge comparison method than others,with an increasing accuracy of 6.87%compared to that without the filtering process.Meanwhile,the Kalman filter offers an improvement of 3.04%over the fractal spectrum method,and the adaptability of the moving-average filter in backpropagation neural network discrimination is better than that in other methods,with an increase in 8.48%.The Kalman filtering algorithm has a significant impact on the peak value of the pulse,reaching 4.49%,and it has an insignificant impact on the energy resolution of the spectrum measurement after discrimination.
基金supported by the National Natural Science Foundation of China(Nos.U19A2086,41874121,12205078).
文摘This study proposes a ladder gradient method for neutron and gamma-ray discrimination.The proposed method exhibited state-of-the-art performance with low time consumption,which incorporates two parts:information extraction and discrimination factor calculation.A quasi-continuous spiking cortical model was proposed to extract information from the radiation pulse signals,thus generating an ignition map corresponding to each pulse signal.The ignition map can be used to calculate the discrimination factor.A ladder gradient calculation was introduced to obtain a discrimination factor with low computational complexity.The proposed method was compared with five other discrimination methods to evaluate its robustness and efficacy.Furthermore,the filter adaptability of the pulse-coupled neural network and ladder gradient methods was investigated.Possible reasons for adapting the conditions with different discrimination methods and filters were analyzed.Experiments were conducted in 20 filtering situations with 11 types of filters to determine the most suitable filters for discrimination methods.The experimental results revealed that the three most adaptive filters of the pulse-coupled neural networks and ladder gradient methods are the wavelet,elliptic,and median filters and the elliptic,moving average,and wavelet filters,respectively.
基金supported by the National major scientific research instrument development project(No.11927805)National Natural Science Foundation of China Young Scientists Fund(No.12005134)+2 种基金Shanghai-XFEL Beamline Project(SBP)(No.31011505505885920161A2101001)Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)Shanghai Pujiang Program(No.20PJ1410900).
文摘A transition edge sensor(TES)is extremely sensitive to changes in temperature,and combined with a high-Z metal of a certain thickness,it can realize high-energy resolution measurements of particles such as X-rays.X-rays with energies below 10 keV have a weak penetrating ability,hence,only gold or bismuth of a few micrometers in thickness can guarantee a quantum efficiency higher than 70%.Therefore,the entire structure of the TES X-ray detector in this energy range can be realized using a microfabrication process.However,for X-rays or γ-rays from 10 keV to 200 keV,submillimeter absorber layers are required,which cannot be realized using the microfabrication process.This paper first briefly introduces a set of TES X-ray detectors and their auxiliary systems,and then focuses on the introduction of the TES γ-ray detector with an absorber based on a submillimeter lead-tin alloy sphere.The detector achieved a quantum efficiency above 70% near 100 keV and an energy resolution of approximately 161.5 eV at 59.5 keV.
基金supported by the National Natural Science Foundation of China under Grants No. 62027803, No. 61701095,No. 61601096, No. 61801089, and No. 61971111the Science and Technology Program of Sichuan under Grants No. 2020YFG0044, No. 2020YFG0046, and No. 2021YFG0200+1 种基金the Science and Technology Program under Grant No.2021-JCJQ-JJ-0949the Defense Industrial Technology Development Program under Grant No. JCKY2020110C041。
文摘The marine biological sonar system evolved in the struggle of nature is far superior to the current artificial sonar. Therefore, the development of bionic underwater concealed detection is of great strategic significance to the military and economy. In this paper, a generative adversarial network(GAN) is trained based on the dolphin vocal sound dataset we constructed, which can achieve unsupervised generation of dolphin vocal sounds with global consistency. Through the analysis of the generated audio samples and the real audio samples in the time domain and the frequency domain, it can be proven that the generated audio samples are close to the real audio samples,which meets the requirements of bionic underwater concealed detection.
基金funded by the National Natural Science Foundation of China(No.22108221)Qing-Yuan Yang acknowledges the ShccigQinling Program(SMYJY20220582)
文摘CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should be relied on its environmental impact.In this work,life cycle assessment model evaluates the environmental performance of CO_(2)conversion by photocatalytic reaction process with two different catalysts(NiAl-LDH and Co-ZIF-9).Six impact categories considered in this analysis,including climate change,acidification potential,depletion of abiotic resources,eutrophication potential,ozone layer depletion potential,and photochemical oxidation potential.Results indicated that CO_(2)conversion with Co-ZIF-9 photocatalyst has a better environmental impact than the NiAl-LDH photocatalyst route.Moreover,the Co-ZIF-9 catalyst scenario also has a lower total environmental burden than the conventional CO production route.Sensitivity analysis shows that recycle performance of the catalyst is highly sensitive to the production process in two scenarios.This study could provide a framework for robust decisions in CO_(2)conversion by photocatalytic reaction,which is useful for policymakers to decide the feasibility of industrialization.
基金financially supported by the National Natural Science Foundation of China(No,21901198)the Thousand Talents Programs of Shaanxi Province and Shccig-Qinling Program.
文摘In the semiconductor industry,recovering and capturing SF_(6)gas from the SF_(6)/N_(2)gas mixture has significant environmental and economic benefits.In this work,two Ni-based metal-organic frameworks(MOFs),Ni(i-na)(bdc)_(0.5)(ina=isonicotinic acid,bdc=terephthalic acid)and methyl-functionalized Ni(3-min)(bdc)_(0.5)(3-min=3-methylisonicotinic acid),are constructed for SF_(6)capture.Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)are both highly stable nine-connected porous materials.The pore sizes of these two materials are similar,but the pore environments are different,which has a bearing on the performance of SF_(6)/N_(2)separations.Ni(3-min)(bdc)0.s exhibits higher SF_(6)adsorption capacity(50.5 cm^(3)g^(-1))and IAST(ideal adsorbed solution theory)SF_(6)/N_(2)selectivity(91)owing to its smaller window diameter and suitable pore chemistry.Theoretical calculations indicate that the SF_(6)and N_(2)molecules interact with the framework at different cages,which reduces their competition for adsorption sites.The remarkable separation performance of Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)is further verified by dynamic breakthrough experiments.Thus,these two adsorbents have the potential to be utilized in industrial applications due to their excellent structural stability and recyclability.
基金supported by the National Natural Science Foundation of China(No.21901198)Qing-Yuan Yang acknowledges the Thousand Talents Programs of Shaanxi Province.
文摘Comprehensive Summary Carbon dioxide(CO_(2))capture is one of the most important aspects of reducing global warming.In terms of CO_(2)capture,metal-organic frameworks(MOFs)have several advantages.However,it isn't easy to shape MOFs while maintaining their performance.Herein,we describe the development of a pellet-shaped ultramicroporous MOF,Ni(3-ain)2(3-ain=3-aminoinoisonicotinic acid),that is capable of selectively adsorbing CO_(2).Polyvinyl butyral(PVB)is used as a binder during the production of Ni(3-ain)2 MOF pellets.The adequately shaped material can maintain its crystallinity and exhibit a high CO_(2)adsorption capacity(3.73 mmol·g^(-1))at ambient conditions,which is significantly greater than those obtained for N_(2)(0.63 mmol·g^(-1))and CO(0.90 mmol·g^(-1)).Consequently,this material displays high IAST selectivities for CO_(2)/N_(2)(26.3,15/85,V/V)and CO_(2)/CO(19.2,1/99,V/V).According to the theoretical calculations,Ni(3-ain)2 preferentially adsorbs CO_(2)molecules over N_(2)molecules and CO molecules.The results of experiments on dynamic breakthrough have demonstrated that Ni(3-ain)2 pellets are capable of effectively separating CO_(2)/N_(2)or CO_(2)/CO mixtures under conditions of dynamic flow.Furthermore,the structured MOF materials can be synthesized in one step at kilogram scale.This work provides an avenue for the shaping of MOFs for potential industrial applications in the future.
