Real-Time atomic-level observations of in situ chemical reactions and transformations utilizing high-resolution electron microscopy

1991 ◽  
Vol 22 (6) ◽  
pp. 1323-1329 ◽  
Author(s):  
Zhenchuan Kang ◽  
Leroy Eyring
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Real Time ◽  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Atomic Level ◽  
Resolution Electron

In situ high-resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 512-513 ◽  
Author(s):  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Elevated Temperatures ◽  
High Resolution Electron Microscopy ◽  
Atomic Level ◽  
Video Recorder ◽  
Resolution Electron ◽  
Imaging Conditions ◽  
Major Impediment

In recent years, there have been many dramatic recordings of dynamic behavior, taken at the atomic level by high-resolution electron microscopy. However in the majority of cases, reliance has been placed on the imaging electron beam to bring about the changes in question. There are many disadvantages to this approach, not the least of which is the lack of experimental control available to the operator. Accordingly we have developed the application of a heating holder to achieve stable elevated temperatures at which reactions can be followed under atomic imaging conditions. This article briefly reviews our progress to-date.Our microscope system is quite conventional, showing that there is no major impediment to hot-stage HREM. We have employed a Philips EM 430 ST (300kV) instrument equipped with a Gatan image pick-up device and a commercial video-recorder. The heating holder is the Philips single tilt sideentry model (PW 6592) which we have found works well up to about 875°C. Of course a double tilt holder is preferable but we overcome the tilting limitations by judicious positioning of cross-section specimens. Image stability can be achieved by heating to a temperature below that of the observation for several minutes before "ramping up" to the desired level.

In Situ Real-time Environmental High Resolution Electron Microscopy of Nanometer Size Novel Xerogel Catalysts for Hydrogenation Reactions in Nylon 6,6

2000 ◽  
Vol 6 (4) ◽  
pp. 335-342 ◽  
Author(s):  
Pratibha L. Gai ◽  
Kostantinos Kourtakis ◽  
Stanislav Ziemecki
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Real Time ◽  
High Resolution Electron Microscopy ◽  
Dynamic Surface ◽  
Nanometer Size ◽  
Heterogeneous Catalytic ◽  
Resolution Electron ◽  
Nylon 6,6

AbstractIn situ real-time environmental high resolution electron microscopy (EHREM) under controlled reaction environments permits direct atomic resolution imaging of dynamic surface and sub-surface microstructures of reacting catalysts. Using the EHREM and complementary microscopy methods, we have investigated selective hydrogenation reaction mechanisms over novel xerogel catalysts of ruthenium and Ru with Co and Au promoters on titania supports, and report an alternative heterogeneous catalytic process for the hydrogenation of adiponitrile (ADN) in the manufacture of Nylon 6,6. The direct EHREM observations are supported by ultra-high resolution low voltage scanning electron microscope (SEM) of spatial distributions of the highly dispersed nanometer-size catalyst particles and parallel chemical studies. The results demonstrate the important role of in situ EHREM in the design of heterogeneous catalytic hydrogenation processes on the nanoscale.

In Situ Real-time Environmental High Resolution Electron Microscopy of Nanometer Size Novel Xerogel Catalysts for Hydrogenation Reactions in Nylon 6,6

2000 ◽  
Vol 6 (4) ◽  
pp. 335-342 ◽  
Author(s):  
Pratibha L. Gai ◽  
Kostantinos Kourtakis ◽  
Stanislav Ziemecki
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Real Time ◽  
High Resolution Electron Microscopy ◽  
Dynamic Surface ◽  
Nanometer Size ◽  
Heterogeneous Catalytic ◽  
Resolution Electron ◽  
Nylon 6,6

Abstract In situ real-time environmental high resolution electron microscopy (EHREM) under controlled reaction environments permits direct atomic resolution imaging of dynamic surface and sub-surface microstructures of reacting catalysts. Using the EHREM and complementary microscopy methods, we have investigated selective hydrogenation reaction mechanisms over novel xerogel catalysts of ruthenium and Ru with Co and Au promoters on titania supports, and report an alternative heterogeneous catalytic process for the hydrogenation of adiponitrile (ADN) in the manufacture of Nylon 6,6. The direct EHREM observations are supported by ultra-high resolution low voltage scanning electron microscope (SEM) of spatial distributions of the highly dispersed nanometer-size catalyst particles and parallel chemical studies. The results demonstrate the important role of in situ EHREM in the design of heterogeneous catalytic hydrogenation processes on the nanoscale.

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