Size reduction overview

Friedrich, A.J. Size reduction overview Shear, compression, and impact. Powder and Bulk Engineering, June 2001, 19-25. 

In the past few years a novel approach to chemical engineering has emerged. This new way of treating processes is called Process Intensification (PI). Although many definitions exist for PI, the main goal is to achieve considerable size reductions in chemical plants. Consequently a smaller plant will lead to improvements in the field of HSE, energy consumption and waste reduction. Recently an overview of PI incentives has been given by Stankiewicz et al.1... 

Table 1.1 Overview of the terminology used in relation to particle size reduction, mixing and de-agglomeration ...

Chapter 1 provides an overview of the current rmderstanding of the problem of corrosion. The chapter also provides a brief introduction to nanomaterials in this context. Chapter 2 discusses corrosion basics with referetrce to nanostmctured materials. Chapter 3 addresses theoretical aspects of grain size reduction on corrosion with a model example and comparison with experimental resirlts of nanocrystalline zirconium and its alloys. Chapter 4 provides a good accoimt of the relevant electrochemical aspects of nanostructured materials. The nature of passive film and its correlation with nanocrystallization are explained. Chapter 5 gives a good description of fabrication of electrodeposited nanostructured materials. 

In this chapter, we will review the reaction dynamics studies which has been performed on supported model catalysts in order to unravel the elementary steps of heterogeneous catalytic reactions. In particular we will focus on the aspects that cannot be studied on extended surfaces like the effect of the size and shape of the metal particles and the role of the substrate in the reaction kinetics. In the first part we will describe the experimental methods and techniques used in these studies. Then we present an overview of the preparation and the structural characterization of the metal particle. Later, we will review the adsorption studies of NO, CO and 02. Finally, we will review the two reactions that have been investigated on the supported model catalysts the CO oxidation and the NO reduction by CO. 

The reactivity of supported model catalysts has already been reviewed in detail in 1998 [6]. Here I give a general overview of the specificity of supported nanometersized clusters as model catalysts compared to small clusters (less than 20 atoms) and single-crystal surfaces. Based on two catalytic reactions recently studied in detail— the CO oxidation and the NO reduction by CO—we will see the respective role of the support, the cluster size, and the cluster morphology. 

FIG. 3. (A) An overview of the operation of the Chu-Berman constant coefficient solver (CBCCS). (B) Exploded details of boxes 1, 2, and 3 of A showing the determination of the ininimum step size, the determination of the actual step size, and the determination of the first de solution estimate for the integration point. (C) Exploded details of boxes 4, S, and 6 of A showing the solution acceptance process, the step reduction process, and the step expansion process. 

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