This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature....This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts.展开更多
A carbon supported Pd(Pd/C) catalyst used as the anodic catalyst in the direct formic acid fuel cells(DFAFC) was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate(EDTA) a...A carbon supported Pd(Pd/C) catalyst used as the anodic catalyst in the direct formic acid fuel cells(DFAFC) was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate(EDTA) as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.展开更多
The development of an efficient catalyst for formic acid electrocatalytic oxidation reaction(FAEOR)is of great significance to accelerate the commercial application of direct formic acid fuel cells(DFAFC).Herein,palla...The development of an efficient catalyst for formic acid electrocatalytic oxidation reaction(FAEOR)is of great significance to accelerate the commercial application of direct formic acid fuel cells(DFAFC).Herein,palladium phosphide(PdxPy)porous nanotubes(PNTs)with different phosphide content(i.e.,Pd3P and Pd5P2)are prepared by combining the self-template reduction method of dimethylglyoxime-Pd(II)complex nanorods and succedent phosphating treatment.During the reduction process,the self-removal of the template and the continual inside-outside Ostwald ripening phenomenon are responsible for the generation of the one-dimensional hollow and porous architecture.On the basis of the unique synthetic procedure and structural advantages,Pd3P PNTs with optimized phos phide content show outstanding electroactivity and stability for FAEOR.Im portantly,the strong electronic effect between Pd and P promotes the direct pathway of FAEOR and inhibits the occurrence of the formic acid decomposition reaction,which effectively enhances the FAEOR electroactivity of Pd3P PNTs.In view of the facial synthesis,excellent electroactivity,high stability,and unordinary selectivity,Pd3P PNTs have the potential to be an efficient anode electrocatalyst for DFAFC.展开更多
We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical te...We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical templates for the deposition of tungsten oxide,whereas the excessive TEAB inhibit the formation of spherical tungsten oxide due to the dense molecular layer of TEAB on the tungsten oxide particles.Citric acid(CA)can control the formation rate and structure of the tungsten oxide when its concentration is more than 0.2 mol/L,because of its ability to coordinate with tungsten atoms.The synergistic effect of TEAB and CA facilitates the formation of spherical tungsten oxide with nanorod crown.After being treated by H_(2)at 600 and 650℃,the tungsten oxide particles are reduced to tungsten particles,which maintain the spherical structure of tungsten oxide and have porous structure.展开更多
The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment,but it is still a great challenge.In this work,a relatively simple,safe method for synthesizing...The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment,but it is still a great challenge.In this work,a relatively simple,safe method for synthesizing graphene oxide with much less acid(decrease∼40%)is proposed.With assistance of the heat absorbed from environment and reaction system,the temperature of reaction system of low acid can be well controlled.More interestingly,the graphite can be completely oxidized into graphite oxide by using much less acid,with lowering the production of high-concentration aqueous waste acid(>1 mol/L,decrease∼40%).A series of characterizations show that the prepared graphene oxide has similar yield and functional groups compared with that of using the conventional method.This work provides a safe and environmentally friendly choice for the large-scale production of graphene oxide and its derivative materials.展开更多
To prepare potassium titanate catalyst, a novel citrate acid complex-combustion method using CH3COOK and Ti(OC4H9)4 as raw materials was developed. The crystalline phase and surface morphology of K2Ti205 were invest...To prepare potassium titanate catalyst, a novel citrate acid complex-combustion method using CH3COOK and Ti(OC4H9)4 as raw materials was developed. The crystalline phase and surface morphology of K2Ti205 were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The impact of some factors, such as the type of contact between K2Ti205 and soot, the content of water vapor and SO2 in exhaust, and the repeated use on catalytic activity of K2Ti205 were studied by temperature programmed reaction (TPR). A comparison between the new method and the reported ones on catalytic activity of potassium titanate was investigated. The results showed that K2Ti205 had high catalytic activity and good stability.展开更多
为了减少反应中氮氧化物(NO_(x))排放对环境造成的影响,提高二氧化锡产品纯度、减小粒径,以金属锡粒和稀硝酸为原料,采用液相硝酸氧化法与喷雾干燥工艺结合制备高纯超细二氧化锡颗粒。考察锡源类型、硝酸浓度及滴加速度、反应温度及煅...为了减少反应中氮氧化物(NO_(x))排放对环境造成的影响,提高二氧化锡产品纯度、减小粒径,以金属锡粒和稀硝酸为原料,采用液相硝酸氧化法与喷雾干燥工艺结合制备高纯超细二氧化锡颗粒。考察锡源类型、硝酸浓度及滴加速度、反应温度及煅烧温度等参数对产物的影响,并利用X射线衍射仪、电感耦合等离子体发射光谱仪、扫描电子显微镜、激光粒度仪、比表面积分析仪等对所制备的偏锡酸(H_(2)SnO_(3))和二氧化锡进行结构和性能表征。结果表明:以锡粒为锡源、硝酸质量分数为25%、滴加速度为30 m L/min、反应温度为80℃,经喷雾干燥工艺处理,再经950℃煅烧,最终制得纯度为99.997%、D_(50)为1.15μm、D_(90)为2.44μm、比表面积为3.86 m^(2)/g的二氧化锡,该产品在屏幕显示技术领域有重要应用,可用于制备氧化铟锡粉体材料(ITO)。展开更多
基金supported by the National Natural Science Foundation of China (No. 21507130)the Open Project Program of Beijing National Laboratory for Molecular Sciences (No. 20140142)+3 种基金the Open Project Program of Chongqing Key Laboratory of Environmental Materials and Remediation Technology from Chongqing University of Arts and Sciences (No. CEK1405)the Open Project Program of Jiangsu Key Laboratory of Vehicle Emissions Control (No. OVEC001)the Open Project Program of Chongqing Key Laboratory of Catalysis and Functional Organic Molecules from Chongqing Technology and Business University (1456029)the Chongqing Science & Technology Commission (Nos. cstc2016jcyj A0070, cstc2014pt-gc20002, cstckjcxljrc13)~~
文摘This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts.
基金Supported by the "863" Program of Science and Technology Ministry of China(Nos.2006AA05Z137, 2007AA05Z143 and 2007AA05Z159)National Natural Science Foundation of China(Nos.20433060, 20473038, 20573057 and 20703043)the Natural Science Foundation of Jiangsu Province, China(No.BK2006224).
文摘A carbon supported Pd(Pd/C) catalyst used as the anodic catalyst in the direct formic acid fuel cells(DFAFC) was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate(EDTA) as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.
基金supported by the National Natural Science Foundation of China(21875133 and 51873100)Natural Science Foundation of Shaanxi Province(2020JZ-23)+2 种基金the National Training Program of Innovation and Entrepreneurship for Undergraduates(S202010718130)Fundamental Research Funds for the Central Universities(GK202101005,GK202103062,and 2021CBLZ004)the 111 Project(B14041).
文摘The development of an efficient catalyst for formic acid electrocatalytic oxidation reaction(FAEOR)is of great significance to accelerate the commercial application of direct formic acid fuel cells(DFAFC).Herein,palladium phosphide(PdxPy)porous nanotubes(PNTs)with different phosphide content(i.e.,Pd3P and Pd5P2)are prepared by combining the self-template reduction method of dimethylglyoxime-Pd(II)complex nanorods and succedent phosphating treatment.During the reduction process,the self-removal of the template and the continual inside-outside Ostwald ripening phenomenon are responsible for the generation of the one-dimensional hollow and porous architecture.On the basis of the unique synthetic procedure and structural advantages,Pd3P PNTs with optimized phos phide content show outstanding electroactivity and stability for FAEOR.Im portantly,the strong electronic effect between Pd and P promotes the direct pathway of FAEOR and inhibits the occurrence of the formic acid decomposition reaction,which effectively enhances the FAEOR electroactivity of Pd3P PNTs.In view of the facial synthesis,excellent electroactivity,high stability,and unordinary selectivity,Pd3P PNTs have the potential to be an efficient anode electrocatalyst for DFAFC.
基金Funded by the Key Program of Jiangxi Province on Development and Research(No.20203BBE53058)the Key Program of Ganzhou City on Development and Research(No.202101125003)。
文摘We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical templates for the deposition of tungsten oxide,whereas the excessive TEAB inhibit the formation of spherical tungsten oxide due to the dense molecular layer of TEAB on the tungsten oxide particles.Citric acid(CA)can control the formation rate and structure of the tungsten oxide when its concentration is more than 0.2 mol/L,because of its ability to coordinate with tungsten atoms.The synergistic effect of TEAB and CA facilitates the formation of spherical tungsten oxide with nanorod crown.After being treated by H_(2)at 600 and 650℃,the tungsten oxide particles are reduced to tungsten particles,which maintain the spherical structure of tungsten oxide and have porous structure.
基金the Guangzhou Municipal Science and Technology Bureau(Nos.202002030368,202102080408)for financial support.
文摘The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment,but it is still a great challenge.In this work,a relatively simple,safe method for synthesizing graphene oxide with much less acid(decrease∼40%)is proposed.With assistance of the heat absorbed from environment and reaction system,the temperature of reaction system of low acid can be well controlled.More interestingly,the graphite can be completely oxidized into graphite oxide by using much less acid,with lowering the production of high-concentration aqueous waste acid(>1 mol/L,decrease∼40%).A series of characterizations show that the prepared graphene oxide has similar yield and functional groups compared with that of using the conventional method.This work provides a safe and environmentally friendly choice for the large-scale production of graphene oxide and its derivative materials.
基金the financial supports provided for this research by the Education Department of Liaoning Province of China(No.2009T061)the Ministry of Education of China(No.[2010]1561)
文摘To prepare potassium titanate catalyst, a novel citrate acid complex-combustion method using CH3COOK and Ti(OC4H9)4 as raw materials was developed. The crystalline phase and surface morphology of K2Ti205 were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The impact of some factors, such as the type of contact between K2Ti205 and soot, the content of water vapor and SO2 in exhaust, and the repeated use on catalytic activity of K2Ti205 were studied by temperature programmed reaction (TPR). A comparison between the new method and the reported ones on catalytic activity of potassium titanate was investigated. The results showed that K2Ti205 had high catalytic activity and good stability.
文摘为了减少反应中氮氧化物(NO_(x))排放对环境造成的影响,提高二氧化锡产品纯度、减小粒径,以金属锡粒和稀硝酸为原料,采用液相硝酸氧化法与喷雾干燥工艺结合制备高纯超细二氧化锡颗粒。考察锡源类型、硝酸浓度及滴加速度、反应温度及煅烧温度等参数对产物的影响,并利用X射线衍射仪、电感耦合等离子体发射光谱仪、扫描电子显微镜、激光粒度仪、比表面积分析仪等对所制备的偏锡酸(H_(2)SnO_(3))和二氧化锡进行结构和性能表征。结果表明:以锡粒为锡源、硝酸质量分数为25%、滴加速度为30 m L/min、反应温度为80℃,经喷雾干燥工艺处理,再经950℃煅烧,最终制得纯度为99.997%、D_(50)为1.15μm、D_(90)为2.44μm、比表面积为3.86 m^(2)/g的二氧化锡,该产品在屏幕显示技术领域有重要应用,可用于制备氧化铟锡粉体材料(ITO)。