In this study,the effect of new and used catalyzed diesel particulate filter(CDPF)with different catalyst loadings on the particulate emissions including the particle mass(PM),particle number(PN),particle size distrib...In this study,the effect of new and used catalyzed diesel particulate filter(CDPF)with different catalyst loadings on the particulate emissions including the particle mass(PM),particle number(PN),particle size distribution(PSD)and geometric mean diameter(GMD)from a diesel vehicle were investigated based on a heavy chassis dynamometer.Results showed that more than 97.9%of the PN and 95.4%of the PM were reduced by the CDPF,and the reduction efficiency was enhanced by the catalyst loading.After using the CDPF,the PSD transformed from bimodal to trimodal with the peak shifting towards smaller particle size,more nucleation mode particles were reduced compared with accumulation mode ones,but the reduction effect on the accumulation mode particles was more significantly influenced by the catalyst loading.Notably,the CDPF increased the accumulation mode particles proportion,producing a larger GMD.For the used CDPF,its reduction effect on the particulate emissions enhanced,especially for the PM in accumulation mode.The PSD returned to bimodal,but the peak at accumulation mode began to be higher than that at nucleation mode,illustrating that more nucleation mode particles was removed.The aging of the CDPF resulted in greater effect on the PN-based PSD than that of PM-based PSD,but the effect of catalyst loading on the PN and PM emission factors was weakened.The used CDPF further increased the GMD,and the effect of catalyst loading on the GMD was strengthened,a higher catalyst loading led to a reduction in the GMD.展开更多
In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions...In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.展开更多
Electrochemical CO_(2) reduction is a sustainable method for producing fuels and chemicals using renewable energy sources.Sn is a widely employed catalyst for formate production,with its performance closely influenced...Electrochemical CO_(2) reduction is a sustainable method for producing fuels and chemicals using renewable energy sources.Sn is a widely employed catalyst for formate production,with its performance closely influenced by the catalyst ink formulations and reac-tion conditions.The present study explores the influence of catalyst loading,current density,and binder choice on Sn-based CO_(2) reduc-tion systems.Decreasing catalyst loading from 10 to 1.685 mg·cm^(-2) and increasing current density in highly concentrated bicarbonate solutions significantly enhances formate selectivity,achieving 88%faradaic efficiency(FE)at a current density of−30 mA·cm^(-2) with a cathodic potential of−1.22 V vs.reversible hydrogen electrode(RHE)and a catalyst loading of 1.685 mg·cm^(-2).This low-loading strategy not only reduces catalyst costs but also enhances surface utilization and suppresses the hydrogen evolution reaction.Nafion enhances formate production when applied as a surface coating rather than pre-mixed in the ink,as evidenced by improved faradaic efficiency and lower cathodic potentials.However,this performance still does not match that of binder-free systems because Sn-based catalysts intrinsic-ally exhibit high catalytic activity,making the binder contribution less significant.Although modifying the electrode surface with binders leads to blocked active sites and increased resistance,polyvinylidene fluoride(PVDF)remains promising because of its stability,strength,and conductivity,achieving up to 72%FE to formate at−30 mA·cm^(-2) and−1.66 V vs.RHE.The findings of this research reveal method-ologies for optimizing the catalyst ink formulations and binder utilization to enhance the conversion of CO_(2) to formate,thereby offering crucial insights for the development of a cost-efficient catalyst for high-current-density operations.展开更多
With the development of renewable energy,electrochemical carbon dioxide reduction reaction(CO_(2)RR)has become a potential solution for achieving carbon neutrality.However,until now,due to issues with salt precipitate...With the development of renewable energy,electrochemical carbon dioxide reduction reaction(CO_(2)RR)has become a potential solution for achieving carbon neutrality.However,until now,due to issues with salt precipitate and regeneration of the electrolyte,this technology faces challenges such as difficulty in maintaining long-term stable operation and excessive costs.The pure water CO_(2)electrolyzers are believed to be the ultimate solution to eliminate the salt depreciation and electrolyte issues.This study develops an in-situ method tailored for CO_(2)reduction in pure water.By employing distribution of relaxation times(DRT)analysis and in-situ electrochemical active surface area(ECSA)measurements,we carried out a comprehensive investigation into the mass transport and electrochemical active surface area of gas diffusion electrodes(GDE)under pure water conditions.The maximum 89%CO selectivity and high selectivity(>80%)in the range of 0-300 mA/cm^(2)were achieved using commercial Ag nanoparticles by rational design of catalyst layer.We found that ionomers influence the CO_(2)electrolyzers performance via affecting local pH,GDE-membrane interface,and CO_(2)transport,while catalyst loading mainly influences the active area and CO_(2)transport.This work provides benchmark and insights for future pure water CO_(2)electrolyzers development.展开更多
To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constru...To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon.But the high loading may induce unwanted par-ticle aggregation.In this work,H-PtNi/C with 33%(mass)Pt loading on carbon and monodisperse distri-bution of 3.55 nm PtNi nanoparticles,was prepared by a bimodal-pore route.In electrocatalytic oxygen reduction reaction(ORR),H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C(13.3%(mass))in the half-cell.While in H_(2)-0_(2) MEA,H-PtNi/C delivers the peak power density of 1.51 W·cm^(-2) and the mass transfer limiting current density of 4.4 A·cm^(-2),being 21%and 16%higher than those of L-PtNi/C(1.25 W·cm^(-2),3.8 A·cm^(-2))respectively,which can be ascribed to enhanced mass trans-fer brought by the thinner catalyst layer in the former.In addition,the same method can be used to pre-pare PtFe alloy catalyst with a high-Pt loading of 36%(mass).This work may lead to a range of catalyst materials for the large current density applications,such as fuel cell vehicles.展开更多
Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimi...Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimization of reaction conditions. However, it remains challenging to achieve efficient photo-ATRP with low loadings of both photocatalyst and copper(II). In this study, two donor-acceptor organic PCs based on pyrazino[2,3-f][1,10]phenanthroline were successfully used to achieve efficient Cu(II)-mediated photo-ATRP. These organic PCs exhibit excellent visible light absorption capabilities and thermally activated delayed fluorescence (TADF) properties. Under blue light irradiation, the PCs facilitated highly efficient and oxygen-tolerant polymerization with an extremely low catalyst loading (50 ppb). This system demonstrated a broad applicability to various monomers, achieving successful polymerization of methacrylates, acrylates, and styrene. Additionally, efficient photo-ATRP on a large scale (250 mL) was achieved, resulting in narrow molecular weight polymers with high monomer conversions and high chain-end fidelity. This work provides an in-depth investigation into the regulatory process of photo-ATRP, offering new insights into the intricate mechanism of oxygen tolerance.展开更多
Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the se...Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.展开更多
基金supported by the Shanghai Sailing Program (No.21YF1448900)the Jiangxi Technological Innovation Guidance Plan Project (No.20212BDH80015)。
文摘In this study,the effect of new and used catalyzed diesel particulate filter(CDPF)with different catalyst loadings on the particulate emissions including the particle mass(PM),particle number(PN),particle size distribution(PSD)and geometric mean diameter(GMD)from a diesel vehicle were investigated based on a heavy chassis dynamometer.Results showed that more than 97.9%of the PN and 95.4%of the PM were reduced by the CDPF,and the reduction efficiency was enhanced by the catalyst loading.After using the CDPF,the PSD transformed from bimodal to trimodal with the peak shifting towards smaller particle size,more nucleation mode particles were reduced compared with accumulation mode ones,but the reduction effect on the accumulation mode particles was more significantly influenced by the catalyst loading.Notably,the CDPF increased the accumulation mode particles proportion,producing a larger GMD.For the used CDPF,its reduction effect on the particulate emissions enhanced,especially for the PM in accumulation mode.The PSD returned to bimodal,but the peak at accumulation mode began to be higher than that at nucleation mode,illustrating that more nucleation mode particles was removed.The aging of the CDPF resulted in greater effect on the PN-based PSD than that of PM-based PSD,but the effect of catalyst loading on the PN and PM emission factors was weakened.The used CDPF further increased the GMD,and the effect of catalyst loading on the GMD was strengthened,a higher catalyst loading led to a reduction in the GMD.
基金sponsored by the National Engineering Laboratory for Mobile Source Emission Control Technology (No. NELMS2020A02)Shanghai Sailing Program (No. 21YF1448900)。
文摘In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.
基金financially supported by a PhD Grant from VITO’s Strategic Research Funds(No.2310345).
文摘Electrochemical CO_(2) reduction is a sustainable method for producing fuels and chemicals using renewable energy sources.Sn is a widely employed catalyst for formate production,with its performance closely influenced by the catalyst ink formulations and reac-tion conditions.The present study explores the influence of catalyst loading,current density,and binder choice on Sn-based CO_(2) reduc-tion systems.Decreasing catalyst loading from 10 to 1.685 mg·cm^(-2) and increasing current density in highly concentrated bicarbonate solutions significantly enhances formate selectivity,achieving 88%faradaic efficiency(FE)at a current density of−30 mA·cm^(-2) with a cathodic potential of−1.22 V vs.reversible hydrogen electrode(RHE)and a catalyst loading of 1.685 mg·cm^(-2).This low-loading strategy not only reduces catalyst costs but also enhances surface utilization and suppresses the hydrogen evolution reaction.Nafion enhances formate production when applied as a surface coating rather than pre-mixed in the ink,as evidenced by improved faradaic efficiency and lower cathodic potentials.However,this performance still does not match that of binder-free systems because Sn-based catalysts intrinsic-ally exhibit high catalytic activity,making the binder contribution less significant.Although modifying the electrode surface with binders leads to blocked active sites and increased resistance,polyvinylidene fluoride(PVDF)remains promising because of its stability,strength,and conductivity,achieving up to 72%FE to formate at−30 mA·cm^(-2) and−1.66 V vs.RHE.The findings of this research reveal method-ologies for optimizing the catalyst ink formulations and binder utilization to enhance the conversion of CO_(2) to formate,thereby offering crucial insights for the development of a cost-efficient catalyst for high-current-density operations.
基金supported by the National Natural Science Foundation of China(No.52394204)by the Shanghai Municipal Science and Technology Major Project。
文摘With the development of renewable energy,electrochemical carbon dioxide reduction reaction(CO_(2)RR)has become a potential solution for achieving carbon neutrality.However,until now,due to issues with salt precipitate and regeneration of the electrolyte,this technology faces challenges such as difficulty in maintaining long-term stable operation and excessive costs.The pure water CO_(2)electrolyzers are believed to be the ultimate solution to eliminate the salt depreciation and electrolyte issues.This study develops an in-situ method tailored for CO_(2)reduction in pure water.By employing distribution of relaxation times(DRT)analysis and in-situ electrochemical active surface area(ECSA)measurements,we carried out a comprehensive investigation into the mass transport and electrochemical active surface area of gas diffusion electrodes(GDE)under pure water conditions.The maximum 89%CO selectivity and high selectivity(>80%)in the range of 0-300 mA/cm^(2)were achieved using commercial Ag nanoparticles by rational design of catalyst layer.We found that ionomers influence the CO_(2)electrolyzers performance via affecting local pH,GDE-membrane interface,and CO_(2)transport,while catalyst loading mainly influences the active area and CO_(2)transport.This work provides benchmark and insights for future pure water CO_(2)electrolyzers development.
基金financially supported by the National Key Research and Development Program of China (2019YFB1504503)the National Natural Science Foundation of China (21878030 and 21761162015)
文摘To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon.But the high loading may induce unwanted par-ticle aggregation.In this work,H-PtNi/C with 33%(mass)Pt loading on carbon and monodisperse distri-bution of 3.55 nm PtNi nanoparticles,was prepared by a bimodal-pore route.In electrocatalytic oxygen reduction reaction(ORR),H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C(13.3%(mass))in the half-cell.While in H_(2)-0_(2) MEA,H-PtNi/C delivers the peak power density of 1.51 W·cm^(-2) and the mass transfer limiting current density of 4.4 A·cm^(-2),being 21%and 16%higher than those of L-PtNi/C(1.25 W·cm^(-2),3.8 A·cm^(-2))respectively,which can be ascribed to enhanced mass trans-fer brought by the thinner catalyst layer in the former.In addition,the same method can be used to pre-pare PtFe alloy catalyst with a high-Pt loading of 36%(mass).This work may lead to a range of catalyst materials for the large current density applications,such as fuel cell vehicles.
基金financial support of the National Natural Science Foundation of China(No.22271044).
文摘Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimization of reaction conditions. However, it remains challenging to achieve efficient photo-ATRP with low loadings of both photocatalyst and copper(II). In this study, two donor-acceptor organic PCs based on pyrazino[2,3-f][1,10]phenanthroline were successfully used to achieve efficient Cu(II)-mediated photo-ATRP. These organic PCs exhibit excellent visible light absorption capabilities and thermally activated delayed fluorescence (TADF) properties. Under blue light irradiation, the PCs facilitated highly efficient and oxygen-tolerant polymerization with an extremely low catalyst loading (50 ppb). This system demonstrated a broad applicability to various monomers, achieving successful polymerization of methacrylates, acrylates, and styrene. Additionally, efficient photo-ATRP on a large scale (250 mL) was achieved, resulting in narrow molecular weight polymers with high monomer conversions and high chain-end fidelity. This work provides an in-depth investigation into the regulatory process of photo-ATRP, offering new insights into the intricate mechanism of oxygen tolerance.
基金Supported by the Project funded by China Postdoctoral Science Foundation(2016M590191)the Key Basic Research Items in Application Basic Research Program of Hebei Province(16964502D)
文摘Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.
