FeO;supported on activated carbon(AC) has been shown to be an ideal catalyst for catalytic wet peroxide oxidation(CWPO) due to its high CWPO reaction activity and stability. Although there have been some studies on th...FeO;supported on activated carbon(AC) has been shown to be an ideal catalyst for catalytic wet peroxide oxidation(CWPO) due to its high CWPO reaction activity and stability. Although there have been some studies on the mechanism of Fe/AC catalysis in CWPO, the specific contribution of each component(surface oxygen groups and FeOxon AC) inside an Fe/AC catalyst and their corresponding reaction mechanism remain unclear, and the reaction stability of CWPO catalysts has rarely been discussed. Then the optimal CWPO catalyst in our laboratory, 3%Fe/AC, was selected.(1) By removing certain components on the AC through heat treatment, its contribution to the reaction and the corresponding reaction mechanism were investigated. With the aid of temperature-programmed desorption–mass spectrometry(TPD–MS) and the CWPO reaction, the normalized catalytic contributions of components were shown to be: 37.3%(carboxylic groups), 5.3%(anhydride), 19.3%(ether/hydroxyl),-71.4%(carbonyl groups) and 100%(FeOx),respectively. DFT calculation and EPR analysis confirmed that carboxylic groups and Fe_(2)O_(3) are able to activate the H_(2)O_(2) to generate·OH.(2) The catalysts at were characterized at different reaction times(0 h, 450 h, 900 h, 1350 h, and 1800 h) by TPD–MS and M?ssbauer spectroscopy. Results suggested that the number of carboxylic goups gradually increased and the size of paramagnetic Fe_(2)O_(3) particle crystallites gradually increased as the reactions progressed. The occurrence of strong interactions between metal oxides and AC was also confirmed. Due to these effects, the strong stability of 3%Fe/AC was further improved. Therefore, the reasons for the high activity and strong stability of 3%Fe/AC in CWPO were clearly shown. We believe that this work provides an idea of the removal of cresols from wastewater into the introduction to show the potential applications of CWPO.展开更多
To study the modification mechanism of activated carbon(AC)by Fe and the low-temperature NH_(3)-selective catalytic reduction(SCR)denitration mechanism of Fe/AC catalysts,Fe/AC catalysts were prepared using coconut sh...To study the modification mechanism of activated carbon(AC)by Fe and the low-temperature NH_(3)-selective catalytic reduction(SCR)denitration mechanism of Fe/AC catalysts,Fe/AC catalysts were prepared using coconut shell AC activated by nitric acid as the support and iron oxide as the active component.The crystal structure,surface morphology,pore structure,functional groups and valence states of the active components of Fe/AC catalysts were characterised by X-ray diffraction,scanning electron microscopy,nitrogen adsorption and desorption,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,respectively.The effect of Fe loading and calcination temperature on the low-temperature denitration of NH_(3)-SCR over Fe/AC catalysts was studied using NH_(3)as the reducing gas at low temperature(150℃).The results show that the iron oxide on the Fe/AC catalyst is spherical and uniformly dispersed on the surface of AC,thereby improving the crystallisation performance and increasing the number of active sites and specific surface area on AC in contact with the reaction gas.Hence,a rapid NH_(3)-SCR reaction was realised.When the roasting temperature remains constant,the iron oxide crystals formed by increasing the amount of loading can enter the AC pore structure and accumulate to form more micropores.When the roasting temperature is raised from 400 to 500℃,the iron oxide is mainly transformed fromα-Fe_(2)O_(3)toγ-Fe_(2)O_(3),which improves the iron oxide dispersion and increases its denitration active site,allowing gas adsorption.When the Fe loading amount is 10%,and the roasting temperature is 500℃,the NO removal rate of the Fe/AC catalyst can reach 95%.According to the study,the low-temperature NH_(3)-SCR mechanism of Fe/AC catalyst is proposed,in which the redox reaction between Fe~(2+)and Fe~(3+)will facilitate the formation of reactive oxygen vacancies,which increases the amount of oxygen adsorption on the surface,especially the increase in surface acid sites,and promotes and adsorbs more reaction gases(NH_(3),O_(2),NO).The transformation from the standard SCR reaction to the fast SCR reaction is accelerated.展开更多
A series of Fe/AC catalysts for catalytic hydrogenation of CO to light hydrocarbons(LHCs) were prepared by decomposing Fe(CO)5 in an autoclave.The catalysts activities were tested in a high-pressure micro reactor.The ...A series of Fe/AC catalysts for catalytic hydrogenation of CO to light hydrocarbons(LHCs) were prepared by decomposing Fe(CO)5 in an autoclave.The catalysts activities were tested in a high-pressure micro reactor.The results show that both CO conversion and LHCs selectivity were significantly affected by the amount of Fe loaded onto the catalysts.The optimum Fe content was determined to be 10% by weight of the catalyst.Over the corresponding catalyst(i.e.,10% Fe/C catalyst),the conversion of CO and the selectivity of LHCs were 94.8% and 59.2%,respectively,at 360 °C.Based on various catalyst characterization techniques,such as XRD,BET and SEM,the catalysts surface areas and pore volume decreased and the smaller particles agglomerated at the edges and corners in the outer region of the support with the increasing Fe content.The agglomerated particles increased greatly when the iron content of the catalyst was higher than 10%.The decrease of catalyst activity can be due to the agglomerated particles.展开更多
采用浸渍法制备负载双金属(铁和铈)活性炭(Fe-Ce/AC),以Fe-Ce/AC为非均相Fenton催化剂处理兰炭废水。在单因素实验基础下,以pH值及H_2O_2和Fe-Ce/AC投加量为考察因素,兰炭废水COD去除率为评价指标,确定H_2O_2最佳投加量为3 m L,Fe-Ce/A...采用浸渍法制备负载双金属(铁和铈)活性炭(Fe-Ce/AC),以Fe-Ce/AC为非均相Fenton催化剂处理兰炭废水。在单因素实验基础下,以pH值及H_2O_2和Fe-Ce/AC投加量为考察因素,兰炭废水COD去除率为评价指标,确定H_2O_2最佳投加量为3 m L,Fe-Ce/AC最佳投加量为0.10 g,pH最佳值为4。采用中心组合设计-响应曲面法优化Fe-Ce/AC非均相Fenton技术处理兰炭废水工艺,结果表明,各影响因子显著性顺序为:pH>Fe-Ce/AC投加量>H_2O_2投加量,其中,H_2O_2投加量与Fe-Ce/AC投加量间交互作用显著,模型校正决定系数R2adj=为0.920 9,模型回归项极显著(P<0.000 1),表明模型可信度和准确度高;最佳工艺条件为:pH=3.7,H_2O_2投加量为2.7 m L,Fe-Ce/AC投加量为0.1 g,COD去除率模型预测值为81.31%,与实验值80.05%相比,相对误差为1.55%,表明模型对实验结果有良好的预测性。展开更多
基金funded by the National Natural Science Foundation of China (52100072)the Beijing Natural Science Foundation(8214056)+2 种基金the special fund of Beijing Key Laboratory of Clean Fuels and Efficient Catalytic Emission Reduction Technology,the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21021101)the National Key Research and Development Program of China (2019YFA0705803)Scientific Research Common Program of Beijing Municipal Commission of Education(KM202010017006)。
文摘FeO;supported on activated carbon(AC) has been shown to be an ideal catalyst for catalytic wet peroxide oxidation(CWPO) due to its high CWPO reaction activity and stability. Although there have been some studies on the mechanism of Fe/AC catalysis in CWPO, the specific contribution of each component(surface oxygen groups and FeOxon AC) inside an Fe/AC catalyst and their corresponding reaction mechanism remain unclear, and the reaction stability of CWPO catalysts has rarely been discussed. Then the optimal CWPO catalyst in our laboratory, 3%Fe/AC, was selected.(1) By removing certain components on the AC through heat treatment, its contribution to the reaction and the corresponding reaction mechanism were investigated. With the aid of temperature-programmed desorption–mass spectrometry(TPD–MS) and the CWPO reaction, the normalized catalytic contributions of components were shown to be: 37.3%(carboxylic groups), 5.3%(anhydride), 19.3%(ether/hydroxyl),-71.4%(carbonyl groups) and 100%(FeOx),respectively. DFT calculation and EPR analysis confirmed that carboxylic groups and Fe_(2)O_(3) are able to activate the H_(2)O_(2) to generate·OH.(2) The catalysts at were characterized at different reaction times(0 h, 450 h, 900 h, 1350 h, and 1800 h) by TPD–MS and M?ssbauer spectroscopy. Results suggested that the number of carboxylic goups gradually increased and the size of paramagnetic Fe_(2)O_(3) particle crystallites gradually increased as the reactions progressed. The occurrence of strong interactions between metal oxides and AC was also confirmed. Due to these effects, the strong stability of 3%Fe/AC was further improved. Therefore, the reasons for the high activity and strong stability of 3%Fe/AC in CWPO were clearly shown. We believe that this work provides an idea of the removal of cresols from wastewater into the introduction to show the potential applications of CWPO.
基金Funded by the General Project of Science and Technology Plan of Yunnan Science and Technology Department(Nos.202001AT070029,2019FB077)Open Fund of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(No.FMRUlab-20-4)。
文摘To study the modification mechanism of activated carbon(AC)by Fe and the low-temperature NH_(3)-selective catalytic reduction(SCR)denitration mechanism of Fe/AC catalysts,Fe/AC catalysts were prepared using coconut shell AC activated by nitric acid as the support and iron oxide as the active component.The crystal structure,surface morphology,pore structure,functional groups and valence states of the active components of Fe/AC catalysts were characterised by X-ray diffraction,scanning electron microscopy,nitrogen adsorption and desorption,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,respectively.The effect of Fe loading and calcination temperature on the low-temperature denitration of NH_(3)-SCR over Fe/AC catalysts was studied using NH_(3)as the reducing gas at low temperature(150℃).The results show that the iron oxide on the Fe/AC catalyst is spherical and uniformly dispersed on the surface of AC,thereby improving the crystallisation performance and increasing the number of active sites and specific surface area on AC in contact with the reaction gas.Hence,a rapid NH_(3)-SCR reaction was realised.When the roasting temperature remains constant,the iron oxide crystals formed by increasing the amount of loading can enter the AC pore structure and accumulate to form more micropores.When the roasting temperature is raised from 400 to 500℃,the iron oxide is mainly transformed fromα-Fe_(2)O_(3)toγ-Fe_(2)O_(3),which improves the iron oxide dispersion and increases its denitration active site,allowing gas adsorption.When the Fe loading amount is 10%,and the roasting temperature is 500℃,the NO removal rate of the Fe/AC catalyst can reach 95%.According to the study,the low-temperature NH_(3)-SCR mechanism of Fe/AC catalyst is proposed,in which the redox reaction between Fe~(2+)and Fe~(3+)will facilitate the formation of reactive oxygen vacancies,which increases the amount of oxygen adsorption on the surface,especially the increase in surface acid sites,and promotes and adsorbs more reaction gases(NH_(3),O_(2),NO).The transformation from the standard SCR reaction to the fast SCR reaction is accelerated.
基金supported by the National Natural Science Foundation of China (No. 50921002)the National Basic Research Program of China (No. 2005CB221204-G)the Program of the Universities in Jiangsu Province for Development of High-Tech Industries (No. JHB05-33)
文摘A series of Fe/AC catalysts for catalytic hydrogenation of CO to light hydrocarbons(LHCs) were prepared by decomposing Fe(CO)5 in an autoclave.The catalysts activities were tested in a high-pressure micro reactor.The results show that both CO conversion and LHCs selectivity were significantly affected by the amount of Fe loaded onto the catalysts.The optimum Fe content was determined to be 10% by weight of the catalyst.Over the corresponding catalyst(i.e.,10% Fe/C catalyst),the conversion of CO and the selectivity of LHCs were 94.8% and 59.2%,respectively,at 360 °C.Based on various catalyst characterization techniques,such as XRD,BET and SEM,the catalysts surface areas and pore volume decreased and the smaller particles agglomerated at the edges and corners in the outer region of the support with the increasing Fe content.The agglomerated particles increased greatly when the iron content of the catalyst was higher than 10%.The decrease of catalyst activity can be due to the agglomerated particles.
文摘采用浸渍法制备负载双金属(铁和铈)活性炭(Fe-Ce/AC),以Fe-Ce/AC为非均相Fenton催化剂处理兰炭废水。在单因素实验基础下,以pH值及H_2O_2和Fe-Ce/AC投加量为考察因素,兰炭废水COD去除率为评价指标,确定H_2O_2最佳投加量为3 m L,Fe-Ce/AC最佳投加量为0.10 g,pH最佳值为4。采用中心组合设计-响应曲面法优化Fe-Ce/AC非均相Fenton技术处理兰炭废水工艺,结果表明,各影响因子显著性顺序为:pH>Fe-Ce/AC投加量>H_2O_2投加量,其中,H_2O_2投加量与Fe-Ce/AC投加量间交互作用显著,模型校正决定系数R2adj=为0.920 9,模型回归项极显著(P<0.000 1),表明模型可信度和准确度高;最佳工艺条件为:pH=3.7,H_2O_2投加量为2.7 m L,Fe-Ce/AC投加量为0.1 g,COD去除率模型预测值为81.31%,与实验值80.05%相比,相对误差为1.55%,表明模型对实验结果有良好的预测性。
