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1.
郑笑笑  齐思慧  曹彦宁  沈丽娟  区泽棠  江莉龙 《催化学报》2021,42(2):279-287,后插18-后插20
硫化氢(H2S)广泛存在于以煤、石油和天然气等为原料的化工生产过程中,不仅腐蚀管道和设备,而且还会对健康和环境造成危害.因此,高效脱除H2S已成为工业废气减排的重点.在各种方法中,H2S选择性氧化技术(H2S+(1/2)O2→(1/n)Sn+H2O)由于具有设备需求低、反应不受热力学平衡限制、理论转化率可达100%等优点展现出了巨大的应用前景.实现这一过程的关键在于发展高效稳定的催化剂.作为一类新兴的多孔材料,金属-有机骨架材料(MOFs)由于其独特的结构和性质吸引了广泛的研究兴趣.与传统的脱硫材料相比,MOFs的优势主要体现在:1)高度分散的金属原子可作为催化活性中心;2)超高比表面积和规则的孔结构有利于反应物与活性位点之间的接触;3)结构可调变性高,通过在合成过程中有目的地引入配体或调控剂可产生额外的活性位点,满足特定催化的需求.基于以上特点可知,MOFs是一类有潜力的催化剂,但目前将其应用于H2S选择性氧化领域的研究尚处于起步阶段.本文以典型的铁基MOFs MIL-53(Fe)为研究对象,在制备MIL-53(Fe)过程中添加乙酸(HAc)作为调控剂,通过控制HAc的量,得到一系列具有不同形貌的MIL-53(Fe)-xH样品,并将其应用于H2S选择性氧化反应.SEM结果表明,在MIL-53(Fe)的合成过程中引入乙酸可以显著影响样品的形貌和尺寸.活化前后样品的XRD结果表明,HAc具有与对苯二甲酸(H2BDC)相似羧基基团,二者均可与Fe–O团簇配位.此外,TG-DSC结果证实,随着HAc加入量的提高,与Fe^3+形成配位的HAc/H2BDC比值随之增加.FT-IR和Raman结果进一步证明HAc成功地配位到MIL-53(Fe)的框架中,并且参与配位的HAc可通过真空活化移除从而暴露出Fe^3+不饱和位点.H2S选择性氧化测试表明,MIL-53(Fe)-xH的脱硫活性随着HAc含量的提高先增加然后降低,其中MIL-53(Fe)-5H活性最优.此外,MIL-53(Fe)-5H催化剂在连续运行55 h后仍能保持100%H2S转化率和86%硫选择性,性能远优于传统的Fe2O3催化剂.吡啶原位红外光谱结果表明,HAc的引入可以产生额外的Lewis酸性位点(LAS),LAS含量的不同是造成催化剂活性差异的主要原因.  相似文献   

2.
利用酰胺化反应在2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)分子的4位引入乙酰氨基和异烟酰氨基分别获得Acet-TEMPO和isoNTA-TEMPO分子.将Acet-TEMPO、 isoNTA-TEMPO和TEMPO分别与MIL-101(Fe)组成共催化体系,以苯甲醇选择性氧化为苯甲醛做模型反应,研究上述3种催化体系的催化性能.催化结果表明3种催化体系的催化活性顺序为:MIL-101(Fe)/isoNTA-TEMPO MIL-101(Fe)/Acet-TEMPOMIL-101(Fe)/TEMPO.通过对比实验和吸附实验表明isoNTA-TEMPO的吡啶官能团与MIL-101(Fe)的Fe簇配位作用是提高体系催化性能的关键因素.MIL-101(Fe)/isoNTA-TEMPO催化体系对各种芳香醇均表现出较好的催化性能,且催化剂能循环回收利用.  相似文献   

3.
Superior catalytic performance for selective 1,3-butadiene (1,3-BD) hydrogenation can usually be achieved with supported bimetallic catalysts. In this work, Pt−Co nanoparticles and Pt nanoparticles supported on metal–organic framework MIL-100(Fe) catalysts (MIL=Materials of Institut Lavoisier, PtCo/MIL-100(Fe) and Pt/MIL-100(Fe)) were synthesized via a simple impregnation reduction method, and their catalytic performance was investigated for the hydrogenation of 1,3-BD. Pt1Co1/MIL-100(Fe) presented better catalytic performance than Pt/MIL-100(Fe), with significantly enhanced total butene selectivity. Moreover, the secondary hydrogenation of butenes was effectively inhibited after doping with Co. The Pt1Co1/MIL-100(Fe) catalyst displayed good stability in the 1,3-BD hydrogenation reaction. No significant catalyst deactivation was observed during 9 h of hydrogenation, but its catalytic activity gradually reduces for the next 17 h. Carbon deposition on Pt1Co1/MIL-100(Fe) is the reason for its deactivation in 1,3-BD hydrogenation reaction. The spent Pt1Co1/MIL-100(Fe) catalyst could be regenerated at 200 °C, and regenerated catalysts displayed the similar 1,3-BD conversion and butene selectivity with fresh catalysts. Moreover, the rate-determining step of this reaction was hydrogen dissociation. The outstanding activity and total butene selectivity of the Pt1Co1/MIL-100(Fe) catalyst illustrate that Pt−Co bimetallic catalysts are an ideal alternative for replacing mono-noble-metal-based catalysts in selective 1,3-BD hydrogenation reactions.  相似文献   

4.
Combining scanning tunneling microscopy (STM), IR reflection absorption spectroscopy (IRAS) and molecular beam (MB) techniques, we have investigated particle size effects on a Pd/Fe(3)O(4) model catalyst. We focus on the particle size dependence of (i) CO adsorption, (ii) oxygen adsorption and (iii) Pd nanoparticle oxidation/reduction. The model system, which is based on Pd nanoparticles supported on an ordered Fe(3)O(4) film on Pt(111), is characterized in detail with respect to particle morphology, nucleation, growth and coalescence behavior of the Pd particles. Morphological changes upon stabilization by thermal treatment in oxygen atmosphere are also considered. The size of the Pd particles can be varied roughly between 1 and 100 nm. The growth and morphology of the Pd particles on the Fe(3)O(4)/Pt(111) film were characterized by STM and IRAS of adsorbed CO as a probe molecule. It was found that very small Pd particles on Fe(3)O(4) show a strongly modified adsorption behavior, characterized by atypically weak CO adsorption and a characteristic CO stretching frequency around 2130 cm(-1). This modification is attributed to a strong interaction with the support. Additionally, the kinetics of CO adsorption was studied by sticking coefficient experiments as a function of particle size. For small particles it is shown that the CO adsorption rate is significantly enhanced by the capture zone effect. The absolute size of the capture zone was quantified on the basis of the STM and sticking coefficient data. Finally, oxygen adsorption was studied by means of MB CO titration experiments. Pure chemisorption of oxygen is observed at 400 K, whereas at 500 K partial oxidation of the particles occurs. The oxidation behavior reveals strong kinetic hindrances to oxidation for larger particles, whereas facile oxidation and reduction are observed for smaller particles. For the latter, estimates point to the formation of oxide layers which, on average, are thicker than the surface oxides on corresponding single crystal surfaces.  相似文献   

5.
《中国化学快报》2021,32(11):3505-3508
The conversion of CO2 under mild condition is of great importance because these reactions involving CO2 can not only produce value-added chemicals from abundant and inexpensive CO2 feedstock but also close the carbon cycle. However, the chemical inertness of CO2 requires the development of high-performance catalysts. Herein, Ag nanoparticles/MIL-100(Fe) composites were synthesized by simple impregnation-reduction method and employed as catalysts for the photothermal carboxylation of terminal alkynes with CO2. MIL-100(Fe) could stabilize Ag nanoparticles and prevent them from aggregation during catalytic process. Taking the advantages of photothermal effects and catalytic activities of both Ag nanoparticles and MIL-100(Fe), various aromatic alkynes could be converted to corresponding carboxylic acid products (86%–92% yields) with 1 atm CO2 at room temperature under visible light irradiation when using Ag nanoparticles/MIL-100(Fe) as photothermal catalysts. The catalysts also showed good recyclability with almost no loss of catalytic activity for three consecutive runs. More importantly, the catalytic performance of Ag nanoparticles/MIL-100(Fe) under visible light irradiation at room temperature was comparable to that upon heating, showing that the light source could replace conventional heating method to drive the reaction. This work provided a promising strategy of utilizing solar energy for achieving efficient CO2 conversion to value-added chemicals under mild condition.  相似文献   

6.
Herein, a novel polyaniline-co-polyindole functionalized magnetic porous carbon derived from MIL-53(Fe) was prepared and employed as an excellent nano-adsorbent to preconcentrate trace amounts of nitro-phenols in water and wastewater samples. Briefly, magnetic MIL-53(Fe) was synthesized by the addition of magnetite nanoparticles, terephthalic acid, and FeCl3 to the reaction medium. The magnetic MIL-53(Fe) was pyrolyzed under nitrogen protection to obtain a magnetic porous carbon nanocomposite, and finally, the nanomaterial was functionalized with polyaniline-co-polyindole via oxidation polymerization. The obtained nano-adsorbent was characterized via X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and transmission and scanning electron microscopies. After that, the fabricated nano-material was utilized as an excellent nano-adsorbent for the preconcentration of trace nitro-phenols (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol) in environmental water, and wastewater samples. The detection limits were obtained from 0.1 to 0.15 μg/L after performing the optimization process. The new method was in the range of 0.4–300 μg/L. The proposed method exhibited a good precision from 3.2% to 9.6% for within-day assay, and 5.2%–13.2% for between-day assay at three concentration levels (1, 50, and 250 μg/L). Eventually, this method was utilized to preconcentrate/determine the target analytes in three water, and wastewater samples, satisfactory (relative standard deviations, 5.4%–9.3%; relative recovery, 88%–109%).  相似文献   

7.
通过等体积浸渍法制备了金属有机骨架材料MIL-53(Al) (MIL:Materials of Institut Lavoisier)负载纳米Pd催化剂. 采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对催化剂的结构进行了表征. 催化剂在反应前后XRD衍射峰保持不变,说明载体MIL-53(Al)具有良好的稳定性. 采用TEM对催化剂进行表征,结果表明,MIL-53(Al)的多孔晶体结构有助于形成高度分散的纳米Pd颗粒,样品2.7% (w) Pd/MIL-53 中Pd颗粒的平均粒径为2.21 nm. 该催化剂在CO氧化反应中表现出较高的催化活性,115 ℃达到完全转化. 同时催化剂可循环使用,多次反应后催化活性和催化剂结构都保持稳定.  相似文献   

8.
通过溶剂热法制备了性质稳定的金属有机框架材料MIL-101(Fe),并用于吸附去除水中的微囊藻毒素-LR。采用电子显微镜、傅立叶变换红外光谱(FT-IR)、Zeta电位和N_2吸附-脱附等方法对制备的纳米材料进行了表征。MIL-101(Fe)具有多孔结构和较高的比表面积(375.2 m~2/g),尺寸约为500 nm。考察了pH值、离子强度、温度、吸附时间、浓度等参数对吸附剂吸附能力的影响。结果表明,静电作用和配位作用是主要的作用机理。MIL-101(Fe)对微囊藻毒素-LR的吸附速度很快(20 min内达到吸附平衡),吸附过程符合准二级动力学模型;MIL-101(Fe)对微囊藻毒素-LR表现出良好的吸附性能,其最大吸附量为256.4 mg/g。溶液中存在的腐植酸对MIL-101(Fe)的吸附性能产生一定的影响。受腐殖酸、盐类的影响,相同条件下MIL-101(Fe)对江水中微囊藻毒素-LR的吸附性能有所下降,但仍可达到68.1 mg/g。因此,该方法简便、高效,适用于快速除去污染水体中的微囊藻毒素-LR。  相似文献   

9.
Porous nanosized metal–organic frameworks (MOFs) are becoming possible candidates as drug-delivery nanocarriers for their versatile porous structures and large loadings of drugs. However, controlling synthesis of MOFs with uniform morphology, good biocompatibility and targeting drug delivery is still a challenge, which greatly limits their clinical applications. Herein, a multifunctional nano-sized drug-delivery material MIL-101(Fe)@FU@FA with a uniform particle size about 500 nm was successfully synthesized for targeting therapeutic purposes. The targeting reagent folic acid (FA) molecules are connected on the surface of 5-FU-loaded nanoparticle MIL-101(Fe)-NH2 by a covalent conjugation. Cytotoxicity tests showed that the synthesized nanoparticles are biocompatible and can significantly inhibit cell proliferation on SMMC-7721 cells compared with MIL-101(Fe)@FU and free 5-FU. The cell metastasis and invasion experiments proved that the nanoparticles had a good anti-metastasis ability to tumor cells. Mechanistically, MIL-101(Fe)@FU@FA induces apoptosis of SMMC-7721 cells and block cell cycle progression in the G2/M phase. Taken together, the drug-loaded nanoparticles MIL-101(Fe)@FU@FA have the effect of targeting and sustained release to achieve the therapeutic effect.  相似文献   

10.
This work spotlights the recently discovered photoelectrocatalytic properties of iron-based metal–organic frameworks (MOFs) for water oxidation reaction (WOR) under visible light irradiation. The low efficiency of WOR is one of the biggest difficulties faced by photoelectrochemical solar energy conversion; the development of new photoanodes for WOR is greatly desired. In view of the fact that a higher efficiency for WOR was forecast thanks to the peculiar properties of MOFs, such as a highly ordered framework and homogenous porous structure, the photoelectrodes based on MIL-101(Fe) containing photo-active iron(III) clusters have been fabricated by using a drop-casting method and applied to photoelectrochemical water oxidation as photoanodes. XRD measurements revealed the successful formation of MIL-101(Fe) electrodes while retaining their framework structures. From the results of photoelectrochemical measurements, the optimal thickness of the MIL-101(Fe) electrodes was determined to be ca. 60 μm, and the optimized MIL-101(Fe) electrode was found to promote photoelectrochemical WOR under visible light irradiation more efficiently than conventional α-Fe2O3 electrodes. Moreover, electrochemical impedance spectroscopy measurements demonstrated a lower resistance of charge transfer at the interface between the MOF surface and the electrolyte, resulting in better photoelectrochemical performance of the MIL-101(Fe) electrode.  相似文献   

11.
制备了多种金属-有机骨架(MOF)材料,采用浸渍-化学还原法制备了非晶态Ru-B/MOF催化剂,考察了它们在苯部分加氢反应中的催化性能.催化性能评价结果表明,这些催化剂的初始反应速率(r0)顺序为Ru-B/MIL-53(Al)Ru-B/MIL-53(Al)-NH2Ru-B/UIO-66(Zr)Ru-B/UIO-66(Zr)-NH2Ru-B/MIL-53(Cr)Ru-B/MIL-101(Cr)Ru-B/MIL-100(Fe),环己烯初始选择性(S0)顺序为Ru-B/MIL-53(Al)≈Ru-B/MIL-53(Cr)Ru-B/UIO-66(Zr)-NH2Ru-B/MIL-101(Cr)Ru-B/MIL-53(Al)-NH2Ru-B/UIO-66(Zr)≈Ru-B/MIL-100(Fe).催化性能最好的Ru-B/MIL-53(Al)催化剂上的r0和S0分别为23 mmol·min-1·g-1和72%.采用多种手段,对催化性能差异最为显著的Ru-B/MIL-53(Al)和Ru-B/MIL-100(Fe)催化剂的物理化学性质进行了表征.发现MIL-53(Al)载体能够更好地分散Ru-B纳米粒子,粒子的平均尺寸为3.2 nm,而MIL-100(Fe)载体上Ru-B纳米粒子团聚严重,粒径达46.6 nm.更小的粒径不仅能够提供更多的活性位,而且也有利于环己烯选择性的提高.对Ru-B/MIL-53(Al)催化剂的反应条件进行了优化,在180°C和5 MPa的H2压力下,环己烯得率可达24%,展示了MOF材料用作苯部分加氢催化剂载体的良好前景.  相似文献   

12.
The uptake and adsorption enthalpy of carbon dioxide at 0.2 bar have been studied in three different topical porous MOF samples, HKUST-1, UiO-66(Zr), and MIL-100(Fe), after having been pre-equilibrated under different relative humidities (3, 10, 20, 40%) of water vapor. If in the case of microporous UiO-66, CO(2) uptake remained similar whatever the relative humidity, and correlations were difficult for microporous HKUST-1 due to its relative instability toward water vapor. In the case of MIL-100(Fe), a remarkable 5-fold increase in CO(2) uptake was observed with increasing RH, up to 105 mg g(-1) CO(2) at 40% RH, in parallel with a large decrease in enthalpy measured. Cycling measurements show slight differences for the initial three cycles and complete reversibility with further cycles. These results suggest an enhanced solubility of CO(2) in the water-filled mesopores of MIL-100(Fe).  相似文献   

13.
刘建芳  冉真真  曹琪岩  季生福 《催化学报》2021,42(12):2254-2264
甲醇选择氧化合成甲酸甲酯是获得高附加值甲醇下游化学品的最具吸引力的催化反应工艺之一.目前,甲醇选择氧化的研究大多为气相催化反应,存在反应温度较高和产物选择性较低的难题.甲醇液相选择氧化过程的反应温度较低,反应条件易于控制,产物选择性相对较高.然而,以氧气作为氧化剂的甲醇液相选择氧化反应,有时难以脱离反应体系的爆炸极限.以H2O2为氧化剂的甲醇液相选择氧化反应,可以在温和反应条件下实现甲醇催化选择氧化.含Fe活性组分的催化剂对醇类液相选择氧化具有很好的催化性能,金属有机框架材料(MOFs)在三维空间中具有均匀分布的酸位等催化活性位,因此,含Fe的MOFs催化剂是兼具有氧化还原活性和酸性的双功能催化剂,并且引入另外一些催化活性组分时可以改善催化剂的反应性能.本文以Fe3+和Co2+为金属离子,通过简单的一锅水热法合成了一系列不同Fe/Co摩尔比的MIL-88B(Fex,Co1–x)双功能催化剂,采用X射线粉末衍射、扫描电镜(SEM)、高分辨透射电镜(HRTEM)、傅里叶变换红外光谱、X射线光电子能谱、氮气吸附-脱附和电感耦合等离子体质谱等手段表征了催化剂的结构,研究了Fe和Co催化活性组分在甲醇液相选择氧化一步合成甲酸甲酯反应中的协同作用,提出了甲醇液相H2O2氧化一步合成甲酸甲酯的可能催化反应机理.SEM和HRTEM测试结果表明,MIL-88B(Fex,Co1–x)催化剂为平均长度400–600 nm,宽度100–150 nm的针状形态,Fe和Co元素的分布比较均匀,Co掺杂没有改变MIL-88B(Fex,Co1–x)的拓扑结构.X射线光电子能谱分析结果表明从Co到Fe的供电子效应,Co的引入可以调节Fe中心的电子环境,Fe和Co具有协同催化作用.通过甲醇液相氧化性能测试发现,MIL-88B(Fe0.7,Co0.3)表现出最优的催化性能,使用0.5当量的H2O2为氧化剂,在80℃下反应60 min后,甲醇转化率为34.8%,甲酸甲酯选择性由50.7%(单金属Fe)提高至67.6%.且经过四次催化循环后,MIL-88B(Fe0.7,Co0.3)的催化活性没有明显降低.催化反应机理研究表明,Fe是吸附活化H2O2进而选择氧化甲醇的主要活性中心,H2O2首先在Fe3+上吸附和活化,甲醇通过氢键作用吸附在MOF的骨架O原子上,被逐步氧化为甲酸,然后甲酸与剩余甲醇在Lewis酸性位点Fe3+和Co2+上反应生成甲酸甲酯;Co的掺杂加速了Fe(Ⅲ)/Fe(Ⅱ)的电子转移,提供了更多的配位不饱和金属位点,增强了对中间产物甲酸的吸附,促进了甲酸向甲酸甲酯转化,从而提高产物选择性.  相似文献   

14.
The present study illustrates the importance of the oxidation state of iron within the mesoporous iron trimesate [{Fe(3)O(H(2)O)(2)F(0.81)(OH)(0.19)}{C(6)H(3)(CO(2))(3)}(2)] denoted MIL-100(Fe) (MIL= Material from Institut Lavoisier) during adsorption of molecules that can interact with the accessible metal sites through π-back donation. Adsorption of CO has been first followed by FTIR spectroscopy to quantify the Lewis acid sites in the dehydrated Fe(III) sample, outgassed at 150 °C, and on the partially reduced Fe(II/III), outgassed at 250 °C. The exposure of MIL-100(Fe) to CO(2), propane, propene and propyne has then been studied by FTIR spectroscopy and microcalorimetry. It appears that π-back donating molecules are strongly adsorbed on reduced iron(II) sites despite the weaker Lewis acidity of cus Fe(2+) sites compared to that of Fe(3+) ones, as shown by pyridine adsorption.  相似文献   

15.
A new biocatalyst MP8@MIL-101(Cr/Fe) was prepared by immobilization of a heme octapeptide, Microperoxidase 8 (MP8) within a mixed metal MOF, MIL-101(Cr/Fe). Both MIL-101(Cr/Fe) and MP8@MIL-101(Cr/Fe) were characterized by PXRD, FTIR spectroscopy and TGA. The catalytic activity of MP8@MIL-101(Cr/Fe) for the oxidation of styrene by H2O2 and tBuOOH was then examined under various reaction conditions (nature of the co-solvent and of the oxidant, concentration of the oxidant and of the substrate, time, pH) and compared to that of MP8 alone. Under the best conditions used, MP8@MIL-101(Cr/Fe) was then shown to catalyze the oxidation of styrene about 3 times more efficiently than MP8 alone with approximately 50 % selectivity for styrene oxide.  相似文献   

16.
以MIL-53(Al)、MIL-96(Al)和MIL-120(Al) (MIL: Material Institute of Lavorisier)三种金属有机骨架材料为载体, 采用浸渍法制备了负载廉价金属镍纳米颗粒的催化剂. 将其用于催化硝基苯加氢合成苯胺反应, 发现以MIL-53(Al)为载体制得的催化剂表现出优异的催化性能. 采用不同的镍前驱体, 如硝酸镍、醋酸镍、乙二胺合镍, 制备了一系列Ni/MIL-53(Al)催化剂. 通过X射线衍射、傅里叶变换红外光谱、电感耦合等离子体、N2物理吸附、H2程序升温还原、透射电镜等技术对其进行了表征, 研究了镍前驱体对金属-载体相互作用、镍颗粒尺寸以及分散程度的影响.结果表明:以乙二胺合镍为镍前驱体制得的催化剂具有金属-载体相互作用适中、镍纳米颗粒更小(4-5 nm)和分布更均匀的特点, 在硝基苯加氢反应中表现出优异的催化性能, 硝基苯转化率达到100%.回收重复使用5次后, 此催化剂仍保持催化活性,硝基苯转化率达92%.  相似文献   

17.
基于Fe基金属有机骨架(MOFS)作为载体,采用浸渍法制备了负载6% Mn的Mn/MIL-100(Fe)脱汞剂。在模拟烟气中,搭建固定床研究了Mn/MIF-100(Fe)脱除单质汞(Hg0)性能。采用X射线衍射分析(XRD)、X射线电子能谱(XPS)、N2吸附-脱附(BET)和热重分析(TGA)对材料进行表征。研究表明,Mn/MIF-100(Fe)脱除单质汞(Hg0)效率较高,在250℃,空速(GHSV)为180000h-1时,脱汞(Hg0)效率达82%以上。Mn/MIF-100(Fe)主要的脱汞机理是催化氧化,Mn的负载促进了汞的吸附,并随着烟气温度的提高,单质汞的氧化效率逐渐提高。O2和NO促进汞的脱除,SO2和NH3抑制汞的脱除。Mn/MIL-100(Fe)整体上对复杂烟气的适应能力强。  相似文献   

18.
The application of metal–organic frameworks (MOFs) as SERS-active platforms in multiplex volatile organic compounds (VOCs) detection is still unexplored. Herein, we demonstrate that MIL-100 (Fe) serves as an ideal SERS substrate for the detection of VOCs. The limit of detection (LOD) of MIL-100(Fe) for toluene sensing can reach 2.5 ppm, and can be even further decreased to 0.48 ppb level when “hot spots” in between Au nanoparticles are employed onto MIL-100 (Fe) substrate, resulting in an enhancement factor of 1010. Additionally, we show that MIL-100(Fe) substrate has a unique “sensor array” property allowing multiplex VOCs detection, with great modifiability and expandability by doping with foreign metal elements. Finally, the MIL-100(Fe) platform is utilized to simultaneously detect the different gaseous indicators of lung cancer with a ppm detection limit, demonstrating its high potential for early diagnosis of lung cancer in vivo.  相似文献   

19.
用直流气体放电活化反应蒸发法在玻璃基片上沉积的SnO2超微粒薄膜,研究其过程中各工艺参数对薄膜结构的影响及作用机理.结果表明, SnO2超微粒薄膜粒径随氧分压增加而增大;蒸镀时间的延长有助于SnO2的生成,也使薄膜发生晶化;而增加放电电压,则薄膜出现外延单晶生长趋势.  相似文献   

20.
使用树脂为载体,合成了6种新的双铁(Ⅲ)催化剂,成功的模拟了可溶性甲烷单加氧酶(MMO)的双核铁中心.这是首次使用树脂作为载体合成模拟MMO的非均相催化剂.在室温下以乙腈为溶剂,30%的过氧化氢或特丁基过氧化氢做氧化剂,环己烷或乙苯作为底物的反应中,催化剂具有MMO相似的催化活性.其中,使用大孔氨甲基树脂为载体合成的催化剂能有效地催化乙苯氧化得到较好的转化率(总收率达69.9%,TON值达55.3).同时研究了树脂的颗粒大小及阴离子供体对催化性能的影响.使用粒径0.675~0.280 mm的树脂和ClO-4的阴离子供体所合成的催化剂具有很好的催化活性.最后探讨了催化剂的回收和再利用.  相似文献   

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