PROCESS CYCLES General Concepts

With an operating catalytic cycle for the reductive opening of epoxides at hand, we decided to investigate the preparatively more important formation of carbon—carbon bonds. Inter-molecular addition reactions to a,(3-unsaturated carbonyl compounds have been described for the stoichiometric process of Nugent and RajanBabu [5], The general concept behind the catalytic conditions is outlined in Scheme 12.16. 

General Concept. The development of the fixed-bed process was based upon the idea of using a static bed of catalyst and maintaining a continuous flow of hydrocarbon vapor by the use of multiple reactors (17). Each reactor was submitted to a cycle of operations consisting of ... 

The productivity, rj, of a process is generally defined as the mass of the product, j, produced per unit time and per unit volume it has the dimensions [kg-m" h ]. To clarify this concept, the curve (Fig. 2.11) demonstrates for the example of the discontinuous process whose course was diagrammed in Fig. 2.4. With discontinuous processes, a certain lag time is also necessary between production cycles due to harvesting, emptying, cleaning, and refilling operations. This lag time, tg, is shown on the negative time axis in Fig. 2.11. 

In the development of the second law and the definition of the entropy function, we use the phenomenological approach as we did for the first law. First, the concept of reversible and irreversible processes is developed. The Carnot cycle is used as an example of a reversible heat engine, and the results obtained from the study of the Carnot cycle are generalized and shown to be the same for all reversible heat engines. The relations obtained permit the definition of a thermodynamic temperature scale. Finally, the entropy function is defined and its properties are discussed. 

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