Environmental-cell TEM studies of catalyst particle behavior

In order to fully understand the general loss of activity for supported metal catalysts during the catalytic process, attempts of investigations of the microstructure and of observed structural changes of supported metal catalysts have been made by using environmental-cell TEM (EC-TEM). The EC-TEM used throughout the experiments reported here consists of a Philips-EM430 (300kV) TEM fitted with a Gatan environmental cell (E-cell). The key design feature is the ability to operate at high gas pressure in the specimen region while still maintaining high vacuum in the rest of the microscope. Fig.1 shows a sideview of the schematic arrangement of the E-cell (A). The standard Phi 1ips-EM430 twin pole pieces (B) have been modified by Gatan Inc. (with a resolution better than 0.34nm) in order to accept the E-cell. Specifically, a groove or “terrace” was machined around a diameter of the upper and lower pole pieces in order to seal with the top and bottom 0-rings (C) of the E-cell.