A new method for making ultra-sparse deposits of metal onto particles is described. Atomic beam deposition (ABD) has been performed on well-defined surfaces, but controlled modification of catalytic particles is more difficult. Actual catalysts are quite complex and their surfaces have many defects. This creates a problem because determining how the surface of a real catalyst controls its kinetic performance is extremely difficult unless real catalytic surfaces can be precisely modified. This connection must be made in order to understand how to make catalysts that are more selective and energy efficient. To allow well defined changes in an existing catalyst particle surface, a new atomic beam deposition tool was designed and constructed. The new deposition system consists of a UHV chamber mounted with an electron beam evaporator and a rotating sample tumbler. As the sample holder rotates, particles tumble in the path of the atomic beam enabling uniform deposition of metal atoms on the catalyst particles. An ultra-sparse (submonolayer) deposit of Cu atoms was performed on 210-250 μ silica particles in order to test the precision of this method. The deposit was characterized by transmission electron microscopy (TEM), temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO).

Novel catalyst synthesis technique using atomic beam deposition

2019 Fall National Meeting

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