气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的...气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。展开更多
The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalys...The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalysts was proposed.The process included alkali (NaOH) hydrothermal treatment,sulfuric acid washing,and calcination.Anatase TiO_(2) in spent SCR catalyst was reconstructed by forming Na_(2)Ti_(2)O_(4)(OH)_(2) nanosheet during NaOH hydrothermal treatment and H_(2)Ti_(2)O_(4)(OH)_(2) during sulfuric acid washing.Anatase TiO_(2) was recovered by decomposing H_(2)Ti_(2)O_(4)(OH)_(2) during calcination.The surface pore properties of the recovered anatase TiO_(2) were adequately improved,and its specific surface area (SSA) and pore volume (PV) were 85 m^(2)·g^(-1)and 0.40 cm^(3)·g^(-1),respectively.The elements affecting catalytic abilities(arsenic and sodium) were also removed.The SCR catalyst was resynthesized using the recovered TiO_(2) as raw material,and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst.This study realized the sustainable recycling of anatase TiO_(2) from spent SCR catalyst.展开更多
Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
为了提高CO催化氧化性能,将Pt/TiO_(2)催化剂在液相中进行紫外照射预处理以增加电子−空穴迁移速率,诱导Pt颗粒长大,然后制备不同UV照射时间的Pt/TiO_(2)催化剂,测试样品的催化性能和氧化能力,表征样品表面的活性颗粒直径、金属分散度和...为了提高CO催化氧化性能,将Pt/TiO_(2)催化剂在液相中进行紫外照射预处理以增加电子−空穴迁移速率,诱导Pt颗粒长大,然后制备不同UV照射时间的Pt/TiO_(2)催化剂,测试样品的催化性能和氧化能力,表征样品表面的活性颗粒直径、金属分散度和元素价态,并利用原位红外光谱研究CO催化反应机理的变化。研究结果表明,制备的Pt颗粒直径为1~2 nm,经过8 h UV预处理的Pt/TiO_(2)催化剂颗粒直径最大,Pt0含量增加,且具有最佳的CO催化性能,CO的完全转化温度降低了约45℃,活性位点的TOF提高15倍。通过对反应机理的分析发现,UV照射能减少副反应发生,提高CO转化率。展开更多
文摘气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。
基金supported by the National Natural Science Foundation of China (52274411)the National Natural Science Foundation of China (51904287)the Innovation Academy for Green Manufacture,Chinese Academy of Sciences (IAGM2022D11)。
文摘The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalysts was proposed.The process included alkali (NaOH) hydrothermal treatment,sulfuric acid washing,and calcination.Anatase TiO_(2) in spent SCR catalyst was reconstructed by forming Na_(2)Ti_(2)O_(4)(OH)_(2) nanosheet during NaOH hydrothermal treatment and H_(2)Ti_(2)O_(4)(OH)_(2) during sulfuric acid washing.Anatase TiO_(2) was recovered by decomposing H_(2)Ti_(2)O_(4)(OH)_(2) during calcination.The surface pore properties of the recovered anatase TiO_(2) were adequately improved,and its specific surface area (SSA) and pore volume (PV) were 85 m^(2)·g^(-1)and 0.40 cm^(3)·g^(-1),respectively.The elements affecting catalytic abilities(arsenic and sodium) were also removed.The SCR catalyst was resynthesized using the recovered TiO_(2) as raw material,and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst.This study realized the sustainable recycling of anatase TiO_(2) from spent SCR catalyst.
基金support provided by Zhejiang Provincial Natural Science Foundation of China(No.Y405108)the Department of Education of Zhejiang Province of China(No.20051409)
文摘Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
文摘为了提高CO催化氧化性能,将Pt/TiO_(2)催化剂在液相中进行紫外照射预处理以增加电子−空穴迁移速率,诱导Pt颗粒长大,然后制备不同UV照射时间的Pt/TiO_(2)催化剂,测试样品的催化性能和氧化能力,表征样品表面的活性颗粒直径、金属分散度和元素价态,并利用原位红外光谱研究CO催化反应机理的变化。研究结果表明,制备的Pt颗粒直径为1~2 nm,经过8 h UV预处理的Pt/TiO_(2)催化剂颗粒直径最大,Pt0含量增加,且具有最佳的CO催化性能,CO的完全转化温度降低了约45℃,活性位点的TOF提高15倍。通过对反应机理的分析发现,UV照射能减少副反应发生,提高CO转化率。
