Gas-solid surface reaction

Wicke, E., "Physical Phenomena in Catalysis and in Gas-Solid Surface Reactions" Proc. 1st Int. Conf. on Chem. Reac. Engng., Washington, 1970 American Chemical Society Washington, D.C., 1972. 

Evidence for a gas/solid surface reaction being photocatalytic... 

As many studies of gas-solid surface reactions involving rare earth inter-metallics are in some sense or other related to hydride formation, the interaction with hydrogen shall be of central interest in this section. The interaction of hydrogen with the intermetallic compounds under consideration can be represented schematically by the following sequence of processes ... 

Gas-solid surface reactions take place in the last two steps oxidation during the air-calcination step resulting to oxidic catalysts and reduction/sulfidation in the activation step resulting in metallic/sulfided catalysts. Sintering... 

In the sections that follow, we will delve deeply into the atomistic world of reaction kinetics and learn how to predict the rates of a number of fairly simple zero, first, and second-order reaction processes. While this chapter will focus mostly on simple gas-phase chemical reaction processes, the principles learned here will apply just as well to the solid-state materials kinetic examples that we will confront later in the textbook. This is because bond-breaking and bond-forming processes are remarkably similar at the atomistic level whether they happen between molecules in the gas phase or between atoms in a solid. Thus, most reaction processes can be described using a common set of approaches. Toward the end of the chapter, in preparation for later solid-state applications of reaction kinetic principles, we will examine how reaction rates can be affected by a catalyst or a surface, and we will learn how to model several gas-solid surface reaction processes relevant to materials science and engineering. 

Gas-solid reactions are among the most common type of heterogeneous reaction processes. The platinum surface catalyzed oxidation of hydrogen, discussed in the previous example, is an excellent example of a heterogeneous gas-solid surface reaction process. In Chapter 5, we will smdy a number of different gas-solid kinetic processes in great detail. To prepare for those smdies, in this section we will discuss a few more simple gas-solid surface reaction processes. 

FIGURE 3.8 Schematic illustration of CO poisoning a Pt catalyst snrface. This is an example of a heterogeneous gas-solid surface reaction process and can be described nsing reaction kinetic principles very similar to those we developed for homogeneons gas-phase reactions. 

ALD is a cyclic, self-limiting gas-solid surface reaction process that allows films to be grown one atomic layer at a time. A classical ALD reaction scheme for the deposition of AI2O3 is shown in Figure 5.12. The deposition process consists of two distinct reaction steps that are repeatedly cycled to build up the AI2O3 film layer by layer ... 

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