Transmission electron microscopy environmental

VIII. Recent Advances in In Situ Atomic Resolution-Environmental Transmission Electron Microscopy (ETEM) Under Controlled Reaction Conditions... 

Many hydrogenation and polymerization reactions in the chemical industry are carried out with liquid-phase reactants. An example is the hydrogenation of aliphatic dinitriles to produce diamines (108,109), which are subsequently converted with adipic acid in solution and polymerized to produce linear polyamides, including nylon 6,6. Recently, the development of wet-environmental transmission electron microscopy (wet-ETEM) for direct nanoscale probing of... 

Simonsen SB, Dahl S, Johnson E, Helveg S. Ceria-catalyzed soot oxidation studied by environmental transmission electron microscopy. J Catal. 2008 255 1. 

Abbreviations AAS, atomic absorption spectroscopy AES, Auger electron spectroscopy AFM, atomic force microscopy BE, binding energy DFG, difference frequency generation DFT, density functional theory EBL, electron beam lithography EELS, electron energy loss spectroscopy ETEM, environmental transmission electron microscopy fee, face-centered cubic FEM/FIM, fleld emission... 

Gai PL, Boyes ED, Helveg S, Hansen PL, Giorgio S, Henry CR (2007) Atomic-resolution environmental transmission electron microscopy for probing gas-soUd reactions in heterogeneous catalysis. MRS Bull 32 1... 

For in-situ experiments most commonly used microscopic and spectroscopic techniques are environmental transmission electron microscopy (E-TEM) [207-209], In-situ vibrational spectroscopic [210-212], ambient pressure X-ray photoelectron spectroscopy [206,210,213], X-ray absorption spectroscopy [213,214-217], and Raman spectroscopy [218]. Making use of this in-situ experiments, the solar fuel generation processes will get a new dimension to the state-of-the-art beliefs. Moreover, the catalysts structure, coverage and composition also change with time, the combination of ultrafast of in-situ spectroscopic techniques reveal the structure and catalytic activity relationships (See Table 7) [217]. 

Crozier PA, Oleshko VP, Westwood AD, Cantrell RD. In situ environmental transmission electron microscopy of gas phase Ziegler-Natta catalytic polymerization of propylene. Presented at Institute of Physics Conference Series 2001. 

Sharma, R. and Iqbal, Z. (2004) In situ observations of carbon nanotube formation using environmental transmission electron microscopy. Appl. Phys. Lett., 84, 990-992. 

Serve, A., Epicier, T., Aouine, M., Cadete Santos Aires, F.J., Obeid, E., Tsampas, M., Pajot, K., and Vernoux, P. (2015) Investigations of soot combustion on yttria-stabilized zirconia by environmental transmission electron microscopy (ETEM). Appl. CataL A-Gen. doi http // dx.doi.org/10.1016/j.apcata.2015.02.030... 

Environmental transmission electron microscopy (ETEM) allows direct observation of the soot/catalyst interface to monitor in situ oxidation of the soot. Thermogravimetric (TG) and temperature-programmed methods have been used to study soot combustion in the presence and absence of oxygen, and the properties depend on the accessibility of gaseous oxygen and the location, shape and dimension of the ceria/soot interface (Fig. 8.26). Instead of using ceria on its own as a catalyst for soot oxidation, more studies have... 

Using environmental transmission electron microscopy (ETEM) Simonsen et showed the evolution of ceria-soot contact points. They showed how the soot particles in contact with CeOg are progressively consumed during oxidation. Transmission electron microscopy revealed that soot particles are oxidized in close proximity to the interface but the contacts between ceria and soot are maintained during soot oxidation because they are continuously... 

Transition metal oxides, rare earth oxides and various metal complexes deposited on their surface are typical phases of DeNO catalysts that lead to redox properties. For each of these phases, complementary tools exist for a proper characterization of the metal coordination number, oxidation state or nuclearity. Among all the techniques such as EPR [80], UV-vis [81] and IR, Raman, transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS) and NMR, recently reviewed [82] for their application in the study of supported molecular metal complexes, Raman and IR spectroscopies are the only ones we will focus on. The major advantages offered by these spectroscopic techniques are that (1) they can detect XRD inactive amorphous surface metal oxide phases as well as crystalline nanophases and (2) they are able to collect information under various environmental conditions [83], We will describe their contributions to the study of both the support (oxide) and the deposited phase (metal complex). 

Many of the characterization techniques described in this chapter require ambient or vacuum conditions, which may or may not be translatable to operational conditions. In situ or in opemndo characterization avoids such issues and can provide insight and information under more realistic conditions. Such approaches are becoming more common in X-ray adsorption spectroscopy (XAS) methods ofXANES and EXAFS, in NMR and in transmission electron microscopy where environmental instruments and cells are becoming common. In situ MAS NMR has been used to characterize reaction intermediates, organic deposits, surface complexes and the nature of transition state and reaction pathways. The formation of alkoxy species on zeolites upon adsorption of olefins or alcohols have been observed by C in situ and ex situ NMR [253]. Sensitivity enhancement techniques play an important role in the progress of this area. In operando infrared and RAMAN is becoming more widely used. In situ RAMAN spectroscopy has been used to online monitor synthesis of zeolites in pressurized reactors [254]. Such techniques will become commonplace. 

Mavrocordatos D, Pronk W, Boiler M (2004) Analysis of environmental particles by atomic force microscopy, scanning and transmission electron microscopy. Water Sci Technol 50 9-18... 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

Marchin, S., Putaux, J.L., Pignon, F., Leonil, J. (2007). Effects of the environmental factors on the casein micelle structure studied by cryo-transmission electron microscopy and small-angle X-ray scattering/ultra-small-angle X-ray scattering. Journal of Chemical Physics, 126, 45-101. 

---