The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the e...The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the effect of the iron(Fe)-zinc(Zn)proximity of Fe-Zn bimetallic catalysts on CO_(2)hydrogenation performance.To eliminate the size effect,Fe_(2)O_(3)and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method.By changing the loading sequence or mixing method,a series of Fe-Zn bimetallic catalysts with different Fe-Zn distances are obtained.Combined with a series of characterization techniques and catalytic performances,Fe-Zn bimetallic proximity for compositions of Fe species is discussed.Furthermore,we observe that a smaller Fe-Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides.Appropriate proximity of Fe and Zn(i.e.,Fe_1Zn_(1)-imp and Fe_(1)Zn_(1)-mix samples)results in a suitable ratio of the Fe_5C_(2)and Fe_(3)O_(4)phases,simultaneously promoting the reverse water-gas shift and Fischer-Tropsch synthesis reactions.This study provides insight into the proximity effect of bimetallic catalysts on CO_(2)hydrogenation performance.展开更多
Recently, the online social networks have emerged as one of the important platforms for social users. Among millions of users, famous person from entertainment circle arouse our interest. They promote social relations...Recently, the online social networks have emerged as one of the important platforms for social users. Among millions of users, famous person from entertainment circle arouse our interest. They promote social relationship and establish their reputation via these platforms. To analyze the social influence of entertainment stars we propose and implement a public cloud based framework to crawl celebrities' social messages from Sina Weibo, store the gathered messages and conduct various analysis to assess the socia influence. It consist of three key components: task generation, resource management and task scheduling, and influence analysis. The task generation is responsible of acquiring celebrities' socia accounts and issue crawling tasks. We propose a cross-media method to extract social accounts from webpages. The resource management and task scheduling will dynamic adjust the rented resource to minimize the total computing cost while keeping Qo S. We propose a dynamic instance provisioning strategy based on the large deviation principle. The influence analysis will undertake various types of analysis, such as fan count, posting frequency, textual analysis, and so on. More than 10,000 celebrities' microblogs have been gathered so far, and some related gainers, such as celebrities and ad agencies can gain the illumination brought by our analysis.展开更多
Lower olefins,produced from syngas through Fischer-Tropsch synthesis,has been gaining worldwide attention as a non-petroleum route.However,the process demonstrates limited selectivity for target products.Herein,a hybr...Lower olefins,produced from syngas through Fischer-Tropsch synthesis,has been gaining worldwide attention as a non-petroleum route.However,the process demonstrates limited selectivity for target products.Herein,a hybrid catalyst system utilizing Fe-based catalyst and SAPO-34 was shown to enhance the selectivity toward lower olefins.A comprehensive study was conducted to examine the impact of various operating conditions on catalytic performance,such as space velocity,pressure,and temperature,as well as catalyst combinations,including loading pattern,and mass ratio of metal and zeolite.The findings indicated that the addition of SAPO-34 was beneficial for enhancing catalytic activity.Furthermore,compared with AlPO-34 zeolite,the strong-acid site on SAPO-34 was identified to crack the long-chain hydrocarbons,thus contributing to the lower olefin formation.Nevertheless,an excess of strong-acid sites was found to detrimentally impact the selectivity of lower olefins,attributed to the increased aromatization and polymerization of lower olefins.The detailed analysis of a hybrid catalyst in Fischer-Tropsch synthesis provides a practical strategy for improving lower olefins selectivity,and has broader implications for the application of hybrid catalyst in diverse catalytic systems.展开更多
The Fe-Mn bimetallic catalyst is a potential candidate for the conversion of CO_(2) into value-added chemicals.The interaction between the two metals plays a significant role in determining the catalytic performance,h...The Fe-Mn bimetallic catalyst is a potential candidate for the conversion of CO_(2) into value-added chemicals.The interaction between the two metals plays a significant role in determining the catalytic performance,however which remains controversial.In this study,we aim to investigate the impact of tuning the proximity of Fe-Mn bimetallic catalysts with similar nanoparticle size.And its effect on the physicochemical properties of the catalysts and corresponding performance were investigated.It was found that closer Fe-Mn proximity resulted in enhanced CO_(2) hydrogenation activity and inhibited CH4 formation.The physiochemical properties of prepared catalysts were characterized using X-ray diffraction,H2 temperature programmed reduction,and X-ray photoelectron spectroscopy,revealing that a closer Fe-Mn distance promoted electron transfer from Mn to Fe,thereby facilitating Fe carburization.The adsorption behavior of CO_(2) and the identification of reaction intermediates were analyzed using CO_(2)-temperature programed desorption and in situ Fourier transform infrared spectroscopy,confirming the intimate Fe-Mn sites contributed to CO_(2) adsorption and the formation of HCOO*species,ultimately leading to increased CO_(2) conversion and hydrocarbon production.The discovery of a synergistic effect at the intimate Fe-Mn sites in this study provides valuable insights into the relationship between active sites and promoters.展开更多
基金supported by National Natural Science Foundation of China(Nos.22108200,21938008 and 22121004)Natural Science Foundation of Zhejiang Province(LQ22B060013)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the effect of the iron(Fe)-zinc(Zn)proximity of Fe-Zn bimetallic catalysts on CO_(2)hydrogenation performance.To eliminate the size effect,Fe_(2)O_(3)and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method.By changing the loading sequence or mixing method,a series of Fe-Zn bimetallic catalysts with different Fe-Zn distances are obtained.Combined with a series of characterization techniques and catalytic performances,Fe-Zn bimetallic proximity for compositions of Fe species is discussed.Furthermore,we observe that a smaller Fe-Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides.Appropriate proximity of Fe and Zn(i.e.,Fe_1Zn_(1)-imp and Fe_(1)Zn_(1)-mix samples)results in a suitable ratio of the Fe_5C_(2)and Fe_(3)O_(4)phases,simultaneously promoting the reverse water-gas shift and Fischer-Tropsch synthesis reactions.This study provides insight into the proximity effect of bimetallic catalysts on CO_(2)hydrogenation performance.
基金supported by the Soft Science Research Program of Science&Technology Department of Sichuan Province(2016ZR0097)
文摘Recently, the online social networks have emerged as one of the important platforms for social users. Among millions of users, famous person from entertainment circle arouse our interest. They promote social relationship and establish their reputation via these platforms. To analyze the social influence of entertainment stars we propose and implement a public cloud based framework to crawl celebrities' social messages from Sina Weibo, store the gathered messages and conduct various analysis to assess the socia influence. It consist of three key components: task generation, resource management and task scheduling, and influence analysis. The task generation is responsible of acquiring celebrities' socia accounts and issue crawling tasks. We propose a cross-media method to extract social accounts from webpages. The resource management and task scheduling will dynamic adjust the rented resource to minimize the total computing cost while keeping Qo S. We propose a dynamic instance provisioning strategy based on the large deviation principle. The influence analysis will undertake various types of analysis, such as fan count, posting frequency, textual analysis, and so on. More than 10,000 celebrities' microblogs have been gathered so far, and some related gainers, such as celebrities and ad agencies can gain the illumination brought by our analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.22108200,22108311)the Natural Science Foundation of Zhejiang Province(Grant No.LQ22B060013)the Haihe Laboratory of Sustainable Chemical Transformations for financial support.
文摘Lower olefins,produced from syngas through Fischer-Tropsch synthesis,has been gaining worldwide attention as a non-petroleum route.However,the process demonstrates limited selectivity for target products.Herein,a hybrid catalyst system utilizing Fe-based catalyst and SAPO-34 was shown to enhance the selectivity toward lower olefins.A comprehensive study was conducted to examine the impact of various operating conditions on catalytic performance,such as space velocity,pressure,and temperature,as well as catalyst combinations,including loading pattern,and mass ratio of metal and zeolite.The findings indicated that the addition of SAPO-34 was beneficial for enhancing catalytic activity.Furthermore,compared with AlPO-34 zeolite,the strong-acid site on SAPO-34 was identified to crack the long-chain hydrocarbons,thus contributing to the lower olefin formation.Nevertheless,an excess of strong-acid sites was found to detrimentally impact the selectivity of lower olefins,attributed to the increased aromatization and polymerization of lower olefins.The detailed analysis of a hybrid catalyst in Fischer-Tropsch synthesis provides a practical strategy for improving lower olefins selectivity,and has broader implications for the application of hybrid catalyst in diverse catalytic systems.
基金National Natural Science Foundation of China(Grant Nos.22378311,22108200,and 21938008)Natural Science Foundation of Zhejiang Province(Grant No.LQ22B060013).
文摘The Fe-Mn bimetallic catalyst is a potential candidate for the conversion of CO_(2) into value-added chemicals.The interaction between the two metals plays a significant role in determining the catalytic performance,however which remains controversial.In this study,we aim to investigate the impact of tuning the proximity of Fe-Mn bimetallic catalysts with similar nanoparticle size.And its effect on the physicochemical properties of the catalysts and corresponding performance were investigated.It was found that closer Fe-Mn proximity resulted in enhanced CO_(2) hydrogenation activity and inhibited CH4 formation.The physiochemical properties of prepared catalysts were characterized using X-ray diffraction,H2 temperature programmed reduction,and X-ray photoelectron spectroscopy,revealing that a closer Fe-Mn distance promoted electron transfer from Mn to Fe,thereby facilitating Fe carburization.The adsorption behavior of CO_(2) and the identification of reaction intermediates were analyzed using CO_(2)-temperature programed desorption and in situ Fourier transform infrared spectroscopy,confirming the intimate Fe-Mn sites contributed to CO_(2) adsorption and the formation of HCOO*species,ultimately leading to increased CO_(2) conversion and hydrocarbon production.The discovery of a synergistic effect at the intimate Fe-Mn sites in this study provides valuable insights into the relationship between active sites and promoters.
