Approach and Overview

This chapter describes the application of these tools to the development of a mechanistic kinetic model for the catalytic hydrocracking of heavy paraffins. The basic approach and overview synopsis are presented first. This is followed by a detailed description of the steps involved in model formulation, optimization, and use. 

This paper thus describes the construction of various mechanistic models for paraffins ranging from Cig to Cgo. All the models incorporate mechanistic acidic chemistry and pathways-level metal chemistry for the prototypical bifunctional hydrocracking catalyst, which has both a metal function for hydrogenation/dehydrogenation and an acid function for isomerization and cracking. 

Much of the complexity of these models is better considered bookkeeping than fundamental. That is, there are only roughly 10 different types of reactions or reaction operators underl5dng the process chemistry, which can comprise thousands of literal reactions because of the statistical or combinatorial explosion of matching these reaction operators with all of the feed and product molecules susceptible to each. A related simplification is 

The present modeling approach exploited these notions. The molecules in the paraffin hydrocracking reaction mixture were thus grouped into a few species types (paraffins, olefins, ions, and inhibitors such as NH3), which, in turn, reacted through a limited number of reaction families on the metal (dehydrogenation and hydrogenation) and the acid sites (protonation, hydride-shift, methyl-shift, protonated cyclopropane (PCP) isomerization, 13-scission, and deprotonation). As a result, a small munber of formal reaction operations could be used to generate hundreds of reactions. 

The rate constant information was organized with a QSRC/LFER for each reaction family, as shown in Eq. 1. 

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Mackay, D. M., D. L. Freyberg, P. V. Roberts, and J. A. Cherry, A natural gradient experiment on solute transport in a sand aquifer, 1. Approach and overview of plume movement , Water Resour. Res., 22,2017-2029 (1986). 

The state of the art in developing textile-based sensors extends from sensor fibres to over-coated yams and textiles, but without using a methodical approach, and overviewing the already existing textile-based sensors. Therefore, a standardized tool that allows the development of textile-based sensors for different application fields has been created for textile manufacturers. It is called the smart 7-step tool, and it is described in this section. 

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