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| 1 | 一种简易的硫辅助方法制备多孔蜂窝状的铁超小原子簇和单原子Fe/g-C3N4显示文摘超小原子簇和单原子分散的活性位点(USCAD)催化剂由于其高原子利用率、高活性、高稳定性等优点,成为多相催化领域一个新兴的研究热点.USCAD通常由载体缺陷、配体和分子筛或金属有机框架的孔道和笼锚定.而制备高密度的USCAD催化剂需要载体上有足够的锚定位点.石墨相氮化碳(g-C3N4)具有高稳定性、高密度且均匀分散的氮原子,是制备USCAD催化剂的理想载体.但是传统热解法制备的金属/g-C3N4催化剂通常为块体结构,会导致金属物种被严重包覆,进而导致催化活性下降.加入固体模板可以制备得到多孔金属g-C3N4催化剂,但是后续复杂的除模板过程制约了其实际应用.因此,开发一种简易的无模板方法制备USCAD金属/g-C3N4催化剂具有重要意义.本工作开发了一种简易的硫辅助热解法制备得到蜂窝状结构的高密度(Fe载量为17.7wt%)USCADFe/g-C3N4催化剂.其多孔蜂窝状结构使催化剂能够暴露更多的USCADFe活性位点,增加了活性位点与反应物的可接近性.通过球差电镜和同步辐射X射线吸收技术证明了Fe物种的分散形式.硫辅助热解法只需要在热解铁盐/三聚氰胺前驱体中加入适量的硫源即可得到蜂窝状的USCAD Fe/g-C3N4催化剂.硫元素作为一种'牺牲载体'通过与铁离子配位促进铁物种在前驱体混合物中分散,经过高温煅烧后以SO2的形式释放而不残留在催化剂中,免除了后续的除模板过程.通过TG-MS,XPS和IR等手段证明了硫元素在热解过程中的状态变化.这种硫辅助热解法表现出非常好的普适性,改变硫源种类(硫脲、硫粉、硫氰酸铵)和铁盐种类都可以得到具有蜂窝状孔道结构的USCADFe/g-C3N4催化剂.将催化剂应用于高级氧化过程可以高效降解各种有机污染物(苯酚、亚甲基蓝、亚甲基橙、罗丹明B),催化剂性能远远优于文献报道的其它Fe基催化剂和传统热解法制备的Fe/g-C3N4催化剂.该硫辅助热解法为无模板法制备纳米多孔USCAD金属/g-C3N4催化剂开辟了一条简易可行的途径. | 安素峰 张光辉 刘佳强 李克艳 宛刚 梁言 纪东辉 Jeffrey T.Miller 宋春山 刘伟 刘中民 郭新闻 | 2020 | Chinese Journal of Catalysis2020，41，8： | 3 |
| 2 | CO_(2)消除镓氢物种提升Ga_(2)O_(3)/SiO_(2)丙烷脱氢反应性能显示文摘丙烯是一种基础石油化工原料,在全球石油化工生产中占有重要地位.以丙烯为原料可生产许多石油化学品,如丙烯腈、环氧丙烷和聚丙烯等.经济快速发展带动了丙烯下游衍生物产业的发展,进而增加了对丙烯的需求量,因此尽管近年来丙烯产能逐年上升,丙烯产量与需求量之间仍存在较大缺口.传统的丙烯生产路径主要是石脑油蒸汽裂解和重质油催化裂化.然而,随着石油资源的短缺和页岩气的发展,丙烷脱氢作为一种直接生产丙烯的技术,成为丙烯生产领域的研究热点.近年来,镓基催化剂由于其较少的积碳和较高的催化活性受到了越来越多的关注.镓基催化剂在丙烷脱氢反应中的活性位点也得到了更多研究.在镓基催化剂中,镓氧化物具有丙烷脱氢活性,而丙烷脱氢反应过程中产生的镓氢(Ga^(δ+)-Hx)物种不稳定,且会造成丙烯选择性降低,导致丙烯产率降低.因此,反应过程中原位消除镓氢物种对于提高丙烷脱氢反应性能具有非常重要的意义.本文将CO_(2)作为温和氧化剂引入Ga_(2)O_(3)/SiO_(2)催化的丙烷脱氢反应中,促进不利的中间产物Ga^(δ+)-Hx的转化,再生丙烷脱氢的活性位点Ga^(3+)-O,从而提高催化性能.原位红外光谱实验结果表明,CO_(2)可有效消除Ga^(δ+)-Hx.在不同反应温度下,引入CO_(2)可显著提高Ga_(2)O_(3)/SiO_(2)催化丙烷脱氢的转化率,特别是选择性.反应4.5 h时,3Ga_(2)O_(3)/SiO_(2)催化丙烷脱氢的选择性从93%降低到89%;引入CO_(2)后,丙烯选择性可提高到并维持在93%.Ga_(2)O_(3)负载量由3 wt%提高到10 wt%时,引入CO_(2)仍可促进反应性能.当CO_(2):C3H8由0.5增加到3时,引入CO_(2)带来的反应性能提升基本相同.同时,引入CO_(2)大大减少反应过程中产生的积碳.本文对镓基催化剂丙烷脱氢活性中心的认识和提高丙烷脱氢反应性能提供了新方向. | 刘怡 张光辉 王建洋 朱杰 张新宝 Jeffrey T.Miller 宋春山 郭新闻 | 2021 | Chinese Journal of Catalysis2021，42，12： | 1 |
| 3 | Revealing the surface atomic arrangement of noble metal alkane dehydrogenation catalysts by a stepwise reduction-oxidation approach显示文摘Surface characterization of metal nanoparticles is a critical need in nanocatalysis for in-depth understanding of the structure-function relationships.The surface structure of nanoparticles is often different from the subsurface,and it is challenging to separately characterize the surface and the subsurface.In this work,theoretical calculations and extended X-ray absorption fine structure(EXAFS)analysis illustrate that the surface atoms of noble metals(Pt and Pd)are oxidized in the air,while the subsurface atoms are not easily oxidized.Taking advantage of the oxidation properties,we suggest a stepwise reduction-oxidation approach to determine the surface atomic arrangement of noble metal nanoparticles,and confirm the rationality of this approach by identifying the surface structure of typical 2-3 nm Pt and Pd nanoparticles.The reduction-oxidation approach is applied to characterize the surface structure of model Pd-Sb bimetallic catalyst,which illustrates that the surface Pd is well isolated by Sb atoms with short bond distance at 2.70Å,while there are still Pd-Pd bonds in the subsurface.Density functional theory(DFT)calculations and Pd L edge X-ray absorption near edge structure(XANES)indicate that the isolation of surface Pd significantly decreases the adsorption energies of Pd-hydrocarbon,which leads to the high propylene selectivity and turnover frequency Pd-Sb bimetallic catalyst for propane dehydrogenation. | Chenliang Ye Mao Peng Tingting Cui Xinxin Tang Dingsheng Wang Miaolun Jiao Jeffrey T.Miller Yadong Li | 2023 | Nano Research2023，16，4： | 0 |
| 4 | The proximity between hydroxyl and single atom determines the catalytic reactivity of Rh1/CeO_(2) single-atom catalysts显示文摘The local structure of the metal single-atom site is closely related to the catalytic activity of metal single-atom catalysts(SACs).However,constructing SACs with homogeneous metal active sites is a challenge due to the surface heterogeneity of the conventional support.Herein,we prepared two Rh1/CeO_(2)SACs(0.5Rh1/r-CeO_(2)and 0.5Rh1/c-CeO_(2),respectively)using two shaped CeO_(2)(rod and cube)exposing different facets,i.e.,CeO_(2)(111)and CeO_(2)(100).In CO oxidation reaction,the T100 of 0.5Rh1/r-CeO_(2)SACs is 120°C,while the T100 of 0.5Rh1/c-CeO_(2)SACs is as high as 200°C.Via in-situ CO diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),we found that the proximity between OH group and Rh single atom on the plane surface plays an important role in the catalytic activity of Rh1/CeO_(2)SAC system in CO oxidation.The Rh single atom trapped at the CeO_(2)(111)crystal surface forms the Rh1(OH)adjacent species,which is not found on the CeO_(2)(100)crystal surface at room temperature.Furthermore,during CO oxidation,the OH group far from Rh single atom on the 0.5Rh1/c-CeO_(2)disappears and forms Rh1(OH)adjacent species when the temperature is above 150°C.The formation of Rh1(OH)adjacentCO intermediate in the reaction is pivotal for the excellent catalytic activity,which explains the difference in the catalytic activity of Rh single atoms on two different CeO_(2)planes.The formed Rh1(OH)adjacent-O-Ce structure exhibits good stability in the reducing atmosphere,maintaining the Rh atomic dispersion after CO oxidation even when pre-reduced at high temperature of 500°C.Density functional theory(DFT)calculations validate the unique activity and reaction path of the intermediate Rh1(OH)adjacentCO species formed.This work demonstrates that the proximity between metal single atom and hydroxyl can determine the formation of active intermediates to affect the catalytic performances in catalysis. | Danfeng Wu Shuyun Zhou Congcong Du Juan Li Jianyu Huang Hong-xia Shen Abhaya K.Datye Shan Jiang Jeffrey T.Miller Sen Lin Haifeng Xiong | 2024 | Nano Research2024，17，1： | 0 |
| 5 | Two-dimensional atomically thin Pt layers on MXenes: The role of electronic effects during catalytic dehydrogenation of ethane and propane显示文摘Atomically thin Pt nanolayers were synthesized on the surface of Mo2TiC2 MXenes and used for the catalytic dehydrogenation of ethane and propane into ethylene and propylene,two important chemicals for the petrochemical industry.As compared with Pt nanoparticles,the atomically thin Pt nanolayer catalyst showed superior coke-resistance(no deactivation for 24 h),high activity(turnover frequencies(TOFs)of 0.4–1.2 s^(-1)),and selectivity(>95%)toward ethylene and propylene.The unique Pt nanolayer has a similar geometric surface to Pt nanoparticles,enabling the investigations of the electronic effect on the catalytic performance,where the geometric effect is negligible.It is found that the electronic effect plays a critical role in dehydrogenative product selectivity and catalyst stability.The metal–support interaction is found dependent on the substrate and metal components,providing wide opportunities to explore high-performance MXene-supported metallic catalysts. | Zhe Li Tobias K.Misicko Fan Yang Xiaopeng Liu Zhenwei Wu Xiaoyang Gao Tao Ma Jeffrey T.Miller Daniela S.Mainardi Collin D.Wick Zhenhua Zeng Yang Xiao Yue Wu | 2024 | Nano Research2024，17，3： | 0 |
| 6 | 金掺杂对碳负载钯催化还原性能的促进作用(英文)显示文摘在许多催化应用中双金属的Pd Au催化剂性能优于单金属催化剂.科研人员对具有可控纳米结构和高活性的Pd Au催化剂进行了广泛的研究,但该催化剂的制备需要多步且通常步骤复杂.本文仅通过浸渍和焙烧制得了Au掺杂的负载型Pd催化剂,所得Pd Au/C催化剂用于室温水相三氯乙烯加氢脱氯反应.当Pd和Au负载量分别为1.0 wt%和1.1 wt%时,在经过干燥、空气处理和H_2还原的过程后,所制得的Pd Au/C催化剂活性最高,初始转化频率(TOF)为34.0×10^(–2) mol_(TCE) mol^(–1)Pd s^(–1),是单金属1.0 wt%Pd/C催化剂TOF(2.2×10^(–2) mol_(TCE) mol^(–1)Pd s^(–1))的15倍以上.X射线吸收光谱结果表明,金的加入避免了400 oC焙烧时Pd的氧化.本文还提出了可能的催化剂纳米结构演变路径,以解释所观察到的催化现象. | Yu-lun Fang Kimberly N.Heck Zhun Zhao Lori A.Pretzer Neng Guo Tianpin Wu Jeffrey T.Miller Michael S.Wong | 2016 | Chinese Journal of Catalysis2016，37，10： | 0 |
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