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纤维素原位合成Fe-N-C催化加氢硝基苯到苯胺(英文) 被引量:4
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作者 王昊 刘小好 +2 位作者 许光月 郭子薇 张颖 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第10期1557-1565,共9页
贵金属被广泛用作各种反应的催化剂,然而它们高昂的价格和有限的来源引起了人们对于开发非贵金属催化剂的浓厚兴趣.因此,寻找一种丰富而有效的催化剂来代替贵金属已成为催化领域最重要的任务之一.铁是地球上最丰富、最廉价的过渡金属,... 贵金属被广泛用作各种反应的催化剂,然而它们高昂的价格和有限的来源引起了人们对于开发非贵金属催化剂的浓厚兴趣.因此,寻找一种丰富而有效的催化剂来代替贵金属已成为催化领域最重要的任务之一.铁是地球上最丰富、最廉价的过渡金属,同时铁基催化剂在合成氨,费托合成和选择性还原氮氧化物等方面表现出优异的活性.近年来,廉价高效的氮掺杂碳负载铁催化剂在各种典型的铂催化反应中表现出良好的催化性能,尤其在催化加氢反应中的应用引起了研究人员的关注.本文通过在氨气氛围下共热解纤维素和氯化铁制备了一系列氮掺杂碳负载铁催化剂,并通过元素分析、原子吸收光谱、透射电子显微镜、X射线衍射和X射线光电子能谱等表征方法,探索了催化剂的物理化学性质.同时以硝基苯加氢制备苯胺为模型反应,探究了催化剂制备条件和反应条件对于催化剂活性的影响.其中Fe-N-C-700(通过在氨气氛围下700℃共热解纤维素和氯化铁制备)表现出最佳活性,在5MPa氢气和120℃的条件下反应12h,硝基苯被完全转化,苯胺的收率可达98.0%,同时,该催化剂还显示出良好的可再循环性,5次运行后未见催化活性的显著降低.BET和元素分析结果表明,在热解温度为700℃的条件下制备的催化剂具有最高的比表面积,并且随着热解温度的升高,催化剂中碳元素和铁元素的含量升高,而氢、氮、氧元素的含量都随之下降.根据TEM图像,当热解温度升至600℃时,在碳材料上可以观察到平均尺寸为5.1nm的金属颗粒,分散性较好.进一步将温度升至700℃,观察到平均尺寸为9.1 nm的金属颗粒,并且碳材料的形态结构转变为卷曲的层状.在XRD分析中,600℃时催化剂的衍射峰归因于正交晶系的Fe2N,随着温度升至700℃,Fe2N相消失同时出现了Fe3C相.在HRTEM的图谱中,可以清晰地看到Fe3C相的(031)面的衍射条纹,并且在颗粒周围有约5.2nm厚的石墨碳层包裹.XPS结果表明,当温度达到700℃时,形成石墨化的氮掺杂碳,提高了催化剂活性.结合催化剂表征结果和对比实验,催化剂中铁物种的转变和氮掺杂碳尤其是石墨化的氮掺杂碳的生成可能是影响催化剂活性的主要因素.根据动力学实验,当使用Fe-N-C-700催化剂时,硝基苯加氢反应表观活化能为31.53kJ/mol(报道为91.5kJ/mol),这表明Fe-N-C-700催化剂可以有效地降低反应活化能. 展开更多
关键词 共热解 氮掺杂 碳材料 氢化反应
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Bioinspired MXene-Based User-Interactive Electronic Skin for Digital and Visual Dual-Channel Sensing 被引量:5
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作者 Wentao Cao Zheng Wang +5 位作者 xiaohao liu Zhi Zhou Yue Zhang Shisheng He Daxiang Cui Feng Chen 《Nano-Micro Letters》 SCIE EI CAS CSCD 2022年第7期228-245,共18页
User-interactive electronic skin(e-skin) that could convert mechanical stimuli into distinguishable outputs displays tremendous potential for wearable devices and health care applications. However, the existing device... User-interactive electronic skin(e-skin) that could convert mechanical stimuli into distinguishable outputs displays tremendous potential for wearable devices and health care applications. However, the existing devices have the disadvantages such as complex integration procedure and lack of the intuitive signal display function. Here, we present a bioinspired user-interactive e-skin, which is simple in structure and can synchronously achieve digital electrical response and optical visualization upon external mechanical stimulus. The e-skin comprises a conductive layer with a carbon nanotubes/cellulose nanofibers/MXene nanohybrid network featuring remarkable electromechanical behaviors, and a stretchable elastomer layer, which is composed of silicone rubber and thermochromic pigments. Furthermore, the conductive nanohybrid network with outstanding Joule heating performance can generate controllable thermal energy under voltage input and then achieve the dynamic coloration of silicone-based elastomer. Especially, such an innovative fusion strategy of digital data and visual images enables the e-skin to monitor human activities with evermore intuition and accuracy. The simple design philosophy and reliable operation of the demonstrated e-skin are expected to provide an ideal platform for next-generation flexible electronics. 展开更多
关键词 MXene Electronic skin Electromechanical behavior Joule heating Visualization
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下吸式气化炉高含水生物质气化过程模拟与机器学习研究
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作者 祁风雷 王振 +3 位作者 陆国庆 刘小好 党琪 马培勇 《过程工程学报》 CAS CSCD 北大核心 2024年第1期87-96,共10页
采用机器学习方法和Aspen过程建模分析方法系统研究了含水率对生物质气化过程的影响规律。研究结果表明生物质含水率对气化气低位热值影响较大,含水率升高,热值降低,生物质含水率对碳转化率影响较小;随着空气当量比升高,气化气低位热值... 采用机器学习方法和Aspen过程建模分析方法系统研究了含水率对生物质气化过程的影响规律。研究结果表明生物质含水率对气化气低位热值影响较大,含水率升高,热值降低,生物质含水率对碳转化率影响较小;随着空气当量比升高,气化气低位热值降低,而气化过程碳转化率提高。气化过程能量平衡分析表明,随着生物质含水率升高,气化过程维持能量平衡所需的空气当量比升高。生物质干燥预处理可保证气化气品质,但需消耗部分气化气为干燥供能,并且随着生物质含水率升高,干燥供热消耗的气化气比例提高,消耗比例在含水率20wt%~60wt%阶段近似线性增加,但是当含水率大于60wt%时呈指数升高。 展开更多
关键词 生物质气化 过程仿真 机器学习 干燥预处理 下吸式气化炉
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Glycerol solutions of highly concentrated biomineral counter-ions towards water-responsive mineralization: Demonstration on bacterial cellulose and its application in hard tissue repair
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作者 Yunfei Zhao xiaohao liu +8 位作者 Zhi Zhou Chaobo Feng Nan Luo Jiajun Yan Shuo Tan Yang Lu Feng Chen Bing-Qiang Lu Shisheng He 《Nano Research》 SCIE EI CSCD 2024年第3期2154-2163,共10页
Mineralization has found widespread use in the fabrication of composite biomaterials for hard tissue regeneration.The current mineralization processes are mainly carried out in neutral aqueous solutions of biomineral ... Mineralization has found widespread use in the fabrication of composite biomaterials for hard tissue regeneration.The current mineralization processes are mainly carried out in neutral aqueous solutions of biomineral counter-ions(a pair of cation and anion that form the corresponding minerals at certain conditions),which are stable only at very low concentrations.This typically results in inefficient mineralization and weak control over biomineral formation.Here,we find that,in the organic solvent glycerol,a variety of biomineral counter-ions(e.g.,Ca/PO_(4),Ca/CO_(3),Ca/SO_(4),Mg/PO_(4),or Fe/OH)corresponding to distinct biominerals at significantly high concentrations(up to hundreds-fold greater than those of simulated body fluid(SBF))are able to form translucent and stable solutions(mineralizing solution of highly concentrated counter-ions(MSCIs)),and mineralization can be triggered upon them with external solvents(e.g.,water or ethanol).Furthermore,with pristine bacterial cellulose(BC)membrane as a model,we demonstrate an effective and controllable mineralization performance of MSCIs on organic substrates.This approach not only forms the homogeneous biominerals on the BC fibers and in the interspaces,but also provides regulations over mineralization rate,mineral content,phase,and dopants.The resulting mineralized BC membranes(MBCs)exhibit high cytocompatibility and favor the proliferation of rat bone marrow mesenchymal stem cells(rBMSC).Following this,we prepare a mineralized bone suture(MBS)from MBC for non-weight bearing bone fixation,which then is tested on a rabbit median sternotomy model.It shows firm fixation of the rabbit sternum without causing discernible toxicity or inflammatory response.This study,by extending the mineralization to the organic solution system of highly concentrated counter-ions,develops a promising strategy to design and build targeted mineral-based composites. 展开更多
关键词 BIOMINERALIZATION organic solvent bacterial cellulose(BC) hard tissue repair
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