Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, ...Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%–12% Cr steels with nickel(Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700℃ and above. To minimize the requirement for expensive Ni-base alloys, martensitic 9%–12% Cr steels can be applied to the next highest temperature components of an A-USC power plant, up to a maximum of 650℃. This paper comprehensively describes the research and development of Ni-base alloys and martensitic 9%–12% Cr steels for thick section boiler and turbine components of A-USC power plants, mainly focusing on the long-term creep-rupture strength of base metal and welded joints, strength loss in welded joints, creep-fatigue properties, and microstructure evolution during exposure at elevated temperatures.展开更多
综述了燃料油(主要是汽油和柴油)深度加氢脱硫催化剂的研究进展。汽油精制的主要问题是在深度加氢脱硫的同时减少由于烯烃饱和造成的辛烷值损失;柴油深度加氢脱硫主要是脱除其中的难脱除硫化物及稠环芳烃加氢饱和。TiO_2和 ZrO_2等载体...综述了燃料油(主要是汽油和柴油)深度加氢脱硫催化剂的研究进展。汽油精制的主要问题是在深度加氢脱硫的同时减少由于烯烃饱和造成的辛烷值损失;柴油深度加氢脱硫主要是脱除其中的难脱除硫化物及稠环芳烃加氢饱和。TiO_2和 ZrO_2等载体负载的金属硫化物催化剂比传统加氢脱硫催化剂的活性高。助剂 P 和 F 能减弱载体-金属间相互作用,在 Co(Ni)-Mo(W)/γ-Al_2O_3催化剂中生成更多的高活性Ⅱ型中心。螯合剂能延迟 Co 的硫化,有利于 Co-Mo-S 活性中心的生成。过渡金属磷化物催化剂表现出更高的脱硫、脱氮活性及良好的活性稳定性,它的主要缺点是金属磷化物的分散度较差,活性中心数目较少。过渡金属碳化物和氮化物催化剂对脱硫、脱氮的初活性较高,但使用后表面金属被硫化,催化活性下降。展开更多
A family of 2D transition metal carbides and nitrides known as MXenes has received increasing attention since the discovery of Ti3C2 in 2011. To date, about 30 different MXenes with well-defined structures and propert...A family of 2D transition metal carbides and nitrides known as MXenes has received increasing attention since the discovery of Ti3C2 in 2011. To date, about 30 different MXenes with well-defined structures and properties have been synthesized, and many more are theoretically predicted to exist. Due to the numerous assets including excellent mechanical properties, metallic conductivity,unique in-plane anisotropic structure, tunable band gap, and so on, MXenes rapidly positioned themselves at the forefront of the 2D materials world and have found numerous promising applications. Particular interest is devoted to applications in electrochemical energy storage, whereby 2D MXenes work either as electrodes,additives, separators, or hosts. This review summarizes recent advances in the synthesis, fundamental properties and composites of MXene and highlights the state-of-the-art electrochemical performance of MXene-based electrodes/devices.The progresses in the field of supercapacitors and Li-ion batteries, Li-S batteries, Naand other alkali metal ion batteries are reviewed, and current challenges and new opportunities for MXenes in this surging energy storage field are presented. In the focus of interest is the possibility to boost device-level performance, particularly that of rechargeable batteries, which are of utmost importance in future energy technologies. Very recently, the 2019 Nobel Prize in Chemistry was awarded to the inventors of the Li-ion battery. For sure, this will provide an additional stimulation to study fundamental aspects of electrochemical energy storage.展开更多
Field experiments were conducted in a maize (Zea mays L.)field of a calcareous fluvo-aquic soil in North China Plain for studying the fate and ammonia loss of urea-N applied at seedling stage,as well as the effectiven...Field experiments were conducted in a maize (Zea mays L.)field of a calcareous fluvo-aquic soil in North China Plain for studying the fate and ammonia loss of urea-N applied at seedling stage,as well as the effectiveness of coated calcium carbide(CCC) in reducing N loss and in improving the yield efficiency of urea.Results show that:(1) For the surface-broadcast treatment ammonia volatilization (measured with micro-meteorological technique)took place quickly,reached the peak 20-26hr after application,and then declined gradually;the cumulative ammonia loss approached the maximum 188hr after application (30% of the N applied),and increased only to 32% 284 hr after application;the latter accounted for 71% of the total loss (45% of applied N).(2) In the case of point placement at a depth of 5-10 cm,ammonia loss 188hr after application was only 12% of the N applied,accounting for 40% of the total loss.(3) There was no difference in total loss between the application depths of 6cm and 10 cm,the loss of them was 30% and 29%,respectively.(4) Total loss of N applied at lower rate (40kg N/ha)with point deep placement at 6cm depth was found only 4% of the N applied,it rose up to 30% when the rate of application increased to 80kg N/ ha.(5) The nitrification inhibitor,CCC,seemed to enhance N loss of urea rather than reduce it,and did not show any benefit effect in improving the yield efficiency of urea,which is presumably due to the high potential of ammonia volatilization in the soil and climatic conditions under investigation.展开更多
文摘Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%–12% Cr steels with nickel(Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700℃ and above. To minimize the requirement for expensive Ni-base alloys, martensitic 9%–12% Cr steels can be applied to the next highest temperature components of an A-USC power plant, up to a maximum of 650℃. This paper comprehensively describes the research and development of Ni-base alloys and martensitic 9%–12% Cr steels for thick section boiler and turbine components of A-USC power plants, mainly focusing on the long-term creep-rupture strength of base metal and welded joints, strength loss in welded joints, creep-fatigue properties, and microstructure evolution during exposure at elevated temperatures.
文摘综述了燃料油(主要是汽油和柴油)深度加氢脱硫催化剂的研究进展。汽油精制的主要问题是在深度加氢脱硫的同时减少由于烯烃饱和造成的辛烷值损失;柴油深度加氢脱硫主要是脱除其中的难脱除硫化物及稠环芳烃加氢饱和。TiO_2和 ZrO_2等载体负载的金属硫化物催化剂比传统加氢脱硫催化剂的活性高。助剂 P 和 F 能减弱载体-金属间相互作用,在 Co(Ni)-Mo(W)/γ-Al_2O_3催化剂中生成更多的高活性Ⅱ型中心。螯合剂能延迟 Co 的硫化,有利于 Co-Mo-S 活性中心的生成。过渡金属磷化物催化剂表现出更高的脱硫、脱氮活性及良好的活性稳定性,它的主要缺点是金属磷化物的分散度较差,活性中心数目较少。过渡金属碳化物和氮化物催化剂对脱硫、脱氮的初活性较高,但使用后表面金属被硫化,催化活性下降。
基金support from Empa internal research grantthe SFI-SIRG award under the Agreement Number 18/SIRG/5621+2 种基金National Natural Science Foundation of China(61874166,U1832149)Natural Science Foundation of Gansu province(18JR3RA292)the Fundamental Research Funds for the Central Universities(lzujbky-2017-k21)
文摘A family of 2D transition metal carbides and nitrides known as MXenes has received increasing attention since the discovery of Ti3C2 in 2011. To date, about 30 different MXenes with well-defined structures and properties have been synthesized, and many more are theoretically predicted to exist. Due to the numerous assets including excellent mechanical properties, metallic conductivity,unique in-plane anisotropic structure, tunable band gap, and so on, MXenes rapidly positioned themselves at the forefront of the 2D materials world and have found numerous promising applications. Particular interest is devoted to applications in electrochemical energy storage, whereby 2D MXenes work either as electrodes,additives, separators, or hosts. This review summarizes recent advances in the synthesis, fundamental properties and composites of MXene and highlights the state-of-the-art electrochemical performance of MXene-based electrodes/devices.The progresses in the field of supercapacitors and Li-ion batteries, Li-S batteries, Naand other alkali metal ion batteries are reviewed, and current challenges and new opportunities for MXenes in this surging energy storage field are presented. In the focus of interest is the possibility to boost device-level performance, particularly that of rechargeable batteries, which are of utmost importance in future energy technologies. Very recently, the 2019 Nobel Prize in Chemistry was awarded to the inventors of the Li-ion battery. For sure, this will provide an additional stimulation to study fundamental aspects of electrochemical energy storage.
文摘Field experiments were conducted in a maize (Zea mays L.)field of a calcareous fluvo-aquic soil in North China Plain for studying the fate and ammonia loss of urea-N applied at seedling stage,as well as the effectiveness of coated calcium carbide(CCC) in reducing N loss and in improving the yield efficiency of urea.Results show that:(1) For the surface-broadcast treatment ammonia volatilization (measured with micro-meteorological technique)took place quickly,reached the peak 20-26hr after application,and then declined gradually;the cumulative ammonia loss approached the maximum 188hr after application (30% of the N applied),and increased only to 32% 284 hr after application;the latter accounted for 71% of the total loss (45% of applied N).(2) In the case of point placement at a depth of 5-10 cm,ammonia loss 188hr after application was only 12% of the N applied,accounting for 40% of the total loss.(3) There was no difference in total loss between the application depths of 6cm and 10 cm,the loss of them was 30% and 29%,respectively.(4) Total loss of N applied at lower rate (40kg N/ha)with point deep placement at 6cm depth was found only 4% of the N applied,it rose up to 30% when the rate of application increased to 80kg N/ ha.(5) The nitrification inhibitor,CCC,seemed to enhance N loss of urea rather than reduce it,and did not show any benefit effect in improving the yield efficiency of urea,which is presumably due to the high potential of ammonia volatilization in the soil and climatic conditions under investigation.
