共查询到20条相似文献,搜索用时 0 毫秒
1.
A VPO catalyst prepared in an organic medium has been studied by in situ laser Raman spectroscopy for n-butane oxidation to maleic anhydride. Data could be obtained at low laser power and brief collection times. Raman characterization during continuous flow (steady-state) studies revealed that (VO)2P2O7 was present. Sequential oxidizing (10% O2 in N2) and reducing (2% n-butane in N2) conditions were explored at 350°C and 400°C. These cycling (unsteady-state) operations revealed that formation of V(5+) phases was enhanced during oxidizing conditions. The intensity of Raman bands due to (VO)2P2O7 increased during reducing conditions. 相似文献
2.
In situ Raman spectroscopy is employed to investigate the oxidation of ethanol on the electrolytic silver catalyst under catalytic conditions. Over the temperature range of 300–873 K, the configuration of the surface intermediates is detected. The ethoxide species, acetate species, adsorbed acetaldehyde and surface hydroxide exist on the silver surface. The mechanism for the oxidation of ethanol on the silver surface under industrial conditions is discussed and compared with that obtained in ultrahigh vacuum systems. 相似文献
3.
《中国化学工程学报》2024,73(9):1-14
It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane hydrates.The dissociation behaviors of gas hydrates formed from various NaCl concentration solutions in a quartz sand system at 268.15 K were investigated to reveal the microscopic mechanism of the self-preservation effect under different salt concentrations.Results showed that as the salt concentration rises,the initial rate of hydrate decomposition quickens.Methane hydrate hardly shows self-preservation ability in the 3.35%(mass)NaCl and seawater systems at 268.15 K.Combined the morphology of hydrate observed by the confocal microscope with results obtained from in situ Raman spectroscopy,it was found that during the initial decomposition stage of gas hydrate below the ice point,gas hydrate firstly converts into liquid water and gas molecules,then turns from water to solid ice rather than directly transforming into solid ice and gas molecules.The presence of salt ions interferes with the ability of liquid water to condense into solid ice.The results of this study provide an important guide for the mechanism and application of the self-preservation effect on the storage and transport of gas and the exploitation of natural gas hydrates. 相似文献
4.
5.
6.
Qingwei Liao Yuxiang Yin Jingxin Zhang Wei Si Wei Hou Lei Qin 《International journal of molecular sciences》2022,23(21)
Flexible sensing can disruptively change the physical form of traditional electronic devices to achieve flexibility in information acquisition, processing, transmission, display, and even energy, and it is a core technology for a new generation of the industrial internet. Fabric is naturally flexible and stretchable, and its knitted ability makes it flexibility and stretchability even more adjustable. However, fabric needs to be electrically conductive to be used for flexible sensing, which allows it to carry a variety of circuits. The dip-coating technique is a common method for preparing conductive fabrics, which are made conductive by attaching conductive fillers to the fabrics. However, the adhesion of the conductive fillers on the surface of such conductive fabrics is weak, and the conductive property will decay rapidly because the conductive filler falls off after repeated stretching, limiting the lifespan of flexible electronic devices based on conductive fabric. We chose multifunctional nanosilver as a conductive filler, and we increased the adhesion of nanosilver to fabric fiber by making nanosilver grow in situ and cover the fiber, so as to obtain conductive fabric with good conductivity. This conductive fabric has a minimum square resistance of 9 Ω/sq and has better electrical conductivity and more stable electrical properties than the conductive fabric prepared using the dip-coating process, and its square resistance did not increase significantlyafter 60 stretches. 相似文献
7.
介绍了原位生长法和次生长法生成多晶沸石膜、气体透过性、膜的微观结构和吸附诱导结构的变化对分离性能的影响,多晶沸石膜对气体和液体分离扩展到纳滤和脱盐等方面的研究进展,对其性能的提高和应用作了展望。 相似文献
8.
Miguel Angel Cárdenas Rosestela Perera Norky Villarreal Carmen Rosales José María Pastor 《应用聚合物科学杂志》2007,106(4):2298-2312
Binary blends of metallocene polyethylenes with polyethylenes and polypropylene were made in a co‐rotating twin‐screw extruder. A stretching process was carried out afterwards in the melt state at the extruder's exit to study the effect of the induced orientation on their thermal and tensile properties. Capillary rheometry was performed to the neat polymers to determine the viscosity ratios of the blend components as a function of the shear rate. SEM and Micro‐Raman analyses were done to study the morphology of the stretched and nonstretched blends. As expected, an increase in the modulus and tensile stress was obtained through blending. Additionally, the elastomeric behavior of the metallocene polyethylene (mPE) sample is observed in all blends and it was not lost through blending. Nevertheless, all blends without stretching exhibited a negative deviation of the linear additivity rule of blending. The stretching of the blends made with metallocene polyethylenes as matrices and other types of PEs as dispersed phase did not improve the tensile properties, although some differences in the dispersed phases were found by DSC, and microfibrils could be seen in the drawn mPE/HDPE blend. However, blending with PP produced an improvement in the modulus and tensile stress of the drawn samples in comparison to their undrawn counterpart. The tensile stresses of PP blends are more sensitive to the drawing process than the modulus, which can be attributed to the appearance of large fibril fractions during this process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
9.
10.
Electrochemical redox reactions of poly(1,8-diaminocarbazole) (PDACz) films in aqueous (0.1 M HClO4) and nonaqueous (0.1 M LiClO4 in acetonitrile) solutions were studied by cyclic voltammetry, in situ vis/NIR and Raman spectroscopy. It has been demonstrated that spectroelectrochemical behavior of the polymer is strongly dependent on the nature of the solution used for doping-undoping but not on the medium used for electropolymerization. A redox couples Fe2+/Fe3+, Fe(CN)64−/3− and tertrathiafulvalene were used as the probes for the studies of electroactivity of the oxidized polymer films. The results were discussed in terms of different mechanism of deprotonation process of the polymer in aqueous solution of 0.1 M HClO4 and in 0.1 M LiClO4 solution in aprotic acetonitrile and the reaction schemes in the two media are proposed. 相似文献
11.
Carla Cristina Costa Augusto José Luiz Zotin Arnaldo da Costa Faro Jr. 《Catalysis Letters》2001,74(1-2):37-43
The partial oxidation of methane (POM) to synthesis gas over SiO2-supported Rh and Ru catalysts was studied by in situ microprobe Raman and in situ time-resolved FTIR (TR-FTIR) spectroscopies. The results of in situ microprobe Raman spectroscopic characterization indicated that no Raman band of Rh2O3 was detected at 500°C over the Rh/SiO2 catalyst under a flow of a CH4/O2/Ar (2/1/45, molar ratio) mixture, while the Raman bands of RuO2 can even be detected at 600°C over the Ru/SiO2 catalyst under the same atmosphere. The experiments of in situ TR-FTIR spectroscopic characterizations on the reactions of CH4 over O2 pre-treated Rh/SiO2 and Ru/SiO2 catalysts indicated that the products of CH4 oxidation over Rh/SiO2 and Ru/SiO2 greatly depend on the concentration of O2– species over the catalysts. On the catalysts with high concentration of O2–, CH4 will be completely oxidized to CO2. However, if the concentration of O2– species over the catalysts is low enough, CH4 can be selectively converted to CO without the formation of CO2. The parallel experiments using in situ TR-FTIR spectroscopy to monitor the reaction of the CH4/O2/Ar (2/1/45, molar ratio) mixture over Rh/SiO2 and Ru/SiO2 catalysts show that the mechanisms of synthesis gas formation over the two catalysts are quite different. On the Rh/SiO2 catalyst, synthesis gas is mainly formed by the direct oxidation of CH4, while on the Ru/SiO2 catalyst, the dominant pathway of synthesis gas formation is via the sequence of total oxidation of CH4 followed by reforming of unconverted CH4 with CO2 and H2O. The significant difference in the mechanisms of partial oxidation of CH4 to synthesis gas over Rh/SiO2 and Ru/SiO2 catalysts can be well related to the difference in the concentration of O2– species over the catalysts under the reaction conditions mainly due to the difference in oxygen affinity of the two metals. 相似文献
12.
13.
14.
Zhi Li Kai Liao Hui-Bo Qin Junli Chen Liangliang Ren Fengguang Li Xianren Zhang Bei Liu Guangjin Chen 《American Institute of Chemical Engineers》2019,65(9):e16681
Molecular dynamics was employed to study the inhibition mechanism of vinyl lactam-based kinetic hydrate inhibitors (KHIs). By comparing the inhibition functions of the same KHIs at different initial locations, we found that the KHI molecules on the surface of hydrate nuclei could obviously prolong the hydrate induction time and exhibited the best inhibition effect. The impacts of KHIs on the methane migration and the arrangement of H2O molecules were analyzed at the molecular level. A gas-adsorbing mechanism for KHIs (i.e., the KHIs with an excellent gas adsorption ability could reduce the supersaturation of methane in the aqueous solution, reinforce the migration resistance of methane to the nucleus, and further inhibit the hydrate growth) was proposed. In addition, the conformations of KHI polymer molecules in the aqueous solution are closely related to their inhibitory effect, that is, stretched skeletons and well-organized structures would maximize their inhibitory effect. 相似文献
15.
冷却水系统中腐蚀和水质的现场监测 总被引:2,自引:0,他引:2
综述了冷却水系统中金属腐蚀的几种现场监测方法(试片法、试验管法、线性极化法和监测换热器法)、腐蚀控制的指标、与腐蚀控制密切相关的冷却水水质现场监测的内容及水质控制的指标。 相似文献
16.
生物法净化低浓度甲苯废气装置及其操作特性 总被引:9,自引:1,他引:8
对生物法净化低浓度甲苯废气的适宜装置及其操作特性的研究表明,生物膜填料塔对低浓度甲苯废气的净化性能优于筛板塔及鼓泡塔;生物膜填料塔采用逆流并在液气比0.03~0.1、气速(30~60)m·h~(-1)的条件下操作时,低浓度甲苯废气净化效率可保持在90%以上.经实验验证,本生物膜填料塔对废气中甲苯的同系物同样具有净化作用.并且对再生胶厂、印刷厂、铸造厂、油漆厂等企业的实际生产废气也有良好的净化效果. 相似文献
17.
Sawao Honda Yuma Matsuda Kento Nakashima Yusuke Daiko Shinobu Hashimoto Yuji Iwamoto 《International Journal of Applied Ceramic Technology》2023,20(2):1081-1089
To investigate faster crystallization of zeolite beta by the dry-gel conversion method, the local structure of the dry gel before synthesis was quantitatively evaluated using in situ Raman spectroscopy during the drying process. The dry gel prepared from Si and Al sources, and tetraethylammonium hydroxide solution was crystallized after several hours by the dry-gel conversion method. The conformational change of TEA+ cations was observed during the drying process by the deconvolution of the spectrum, and the conformational change was larger than that during the synthesis process. The rate of conformational change was increased with the drying temperature, and the apparent activation energy was estimated to be 68.2 kJ/mol. The generation and transformation of double three-membered silicate rings (D3Rs) and 4-2 type secondary building units (SBUs), which are essential for the crystallization of zeolite beta, were observed during the drying process. The transformation from D3R to 4-2 SBU in the dry gel during drying process could be confirmed quantitatively by the difference of the time variation for the amounts of these silicate building units estimated by in situ observation. 相似文献
18.
Raman microprobe analysis was used to investigate the changes in the relative concentrations of oxygen and carbon dioxide found in bubbles in silicate glasses containing different amounts of arsenic oxide, sodium nitrate, and/or sodium nitrite after various heat treatments. As expected, analysis of the spectral data clearly indicated that addition of arsenic oxide to the glass accelerates the relative rate of oxygen dissolution with respect to carbon dioxide. Addition of either sodium nitrate or sodium nitrite to the glass composition containing arsenic oxide generates a relative rate of oxygen dissolution that is intermediate between those for the glass containing no refining agent and the silicate glass containing only arsenic oxide. This relative rate of oxygen dissolution is closely related to the amount of As3+ that is present in the glass. 相似文献
19.
20.
As a new advanced oxidation technology, photocatalytic technology has broad application prospects in the field of wastewater treatment. However, in the actual use process, there will be difficulties in catalyst recovery and reuse. This article successfully prepared bacterial cellulose (BC) loaded silver and titanium dioxide nanoparticles (Ag-plated TiO2/BC composite pellicle) by in situ embedding method. BC not only works as the carrier to load TiO2 and Ag NPs but also adsorbs dyes to promote the reaction. As a reusable photocatalytic film, it is convenient to use and recycle in terms of testing and characterization compared with powders. The results show that Ag and TiO2 nanoparticles were closely embedded in BC. We evaluated the photocatalytic degradation performance of the catalyst on methylene blue (MB), active red X-3B, and Rhodamine B. When the reaction time was 2 h, the dye removal rates were 71%, 68%, and 82.6%. At the same time, through the inhibition zone experiment, it was found that the material has a certain inhibitory effect on both Escherichia coli and Staphylococcus aureus. Therefore, the supported catalyst prepared by this method has the advantages of high catalytic activity, relatively stable property, easy recovery, and tailorability, making it potentially applicable in sewage post-treatment links. 相似文献