Alternative reaction engineering

Discontinuous (batch) processes are carried out in pressure vessels (autoclaves) where DMC is maintained as liquid by autogenous pressure. Instead, CF reactions at atmospheric pressure require that both DMC and the reagent(s) in the vapor phase come into contact with a catalytic bed a constraint that has spurred the development of new applications and alternative reaction engineering, namely, GL-PTC and the continuously fed stirred-tank reactor (CSTR). 

Lintz H-G, Reitzmann A. Alternative reaction engineering concepts in partial oxidations on oxidic catalysts. Catalysis Reviews Science Engineering. 2007 49(l) l-32. 

Lintz, H. and Reitzmann, A. (2007). Alternative Reaction Engineering Concepts in Partial Oxidations on Oxidic Catalysts, Catal. Rev., 49, pp. 1-32. 

Figure 1-11 The upper reaction is the methyl isocyanate route used at Bhopal. The lower reaction suggests an alternative reaction scheme using a less hazardous intermediate. Adapted from Chemical and Engineering News (Feb. 11, 1985), p. 30.

A succinct description of the basics of chemical reaction engineering has been presented and its application to the estimation of shelf life has been outlined through examples. These techniques are of crucial importance in NDAs to regulatory agencies such as the FDA. Normally, at the time a new drug application is submitted, not enough data at low temperature are available since long-term studies take years. The tools presented here are the alternative approved by the FDA and ICH. 

Summing up, from the reaction-engineering viewpoint there are a considerable number of alternatives. The most critical factor in design is the availability of an active catalyst and its performance with respect to the raw materials. 

The book is structured to supplement modern texts on kinetics and reaction engineering, not to present an alternative to them. It intentionally concentrates on... 

Which of the two alternatives is more promising will differ from case to case. Usually, the first approach is preferable if a large amount of reliable quantitative kinetic data is already available the second, if the kinetic behavior of the reaction is still largely unknown and the reaction engineer has a say in the design of the... 

The definitions of the heat and mass transfer fluxes are thus merely based on empirical arguments, so in the literature there are given more than one way to interpret the transfer coefficients [15, 139]. Basically, the transfer coefficients are either treated as an alternative model to the fundamental diffusion models (i.e., the Fourier s and Pick s laws) or the transfer coefficients are taking both diffusive and convective mechanisms into account through empirical parameterizations. However, in reaction engineering practice the distingtion between these approaches is rather blurred so it is not always clear which of the fundamental transport processes that are actually implemented. 

The reaction engineering (see Section 8.2.1) is advanced insofar that many alternative process concepts [lie, 15d] were tested during the development phase however, only a few were pursued further in the concept stage up to the pilot plant reactor. There remained the principle of the biphasic Ruhrchemie/Rhone-Poulenc oxo process which was developed in long-term tests and protected by a matched patent strategy, as described in Section 6.1.3. 

The book is structured to supplement modern texts on kinetics and reaction engineering, not to present an alternative to them. It intentionally concentrates on what is not easily available from other sources. Facets and procedures well covered in standard texts—statistical basis, rates of single-step reactions, experimental reactors, determination of reaction orders, auxiliary experimental techniques (isotopic labeling, spectra, etc.)—are sketched only for ease of reference and to place them in context. Emphasis is on a comprehensive presentation of strategies and streamlined mathematics for network elucidation and modeling suited for industrial practice. 

Sonochemical enhancement of reaction rates is caused by a phenomenon called cavitation. Therefore, we largely confine the treatment in this chapter to the chemical and reaction engineering (scale-up) aspects of cavitation and its associated effects (see Shah et al., 1999, for a detailed treatment). An alternative means of achieving the same result is by mimicking the ultrasonic effect by inducing hydrodynamic cavitation. Because of the practical importance of this technique, we conclude the chapter by outlining its main features. 

Indeed, the tuneable properties of ILs associated with their environment-friendly perception have increased their investigation as alternative reaction media to replace traditional organic solvents in organic synthesis [11-13], catalytic reactions [12-16], electrochemical applications [17-19], biochemistry [20-24], and material engineering [25], It has also been reported that ILs can be used in extraction and as liquid phase in supported liquid membranes (SLMs) for the separation and recovery of organic compounds, metals, and gases [26-31]. 

Calculation of the volume of reactor required under real conditions is a centred problem of chemical reaction engineering. But in these applications the rate function r remains the most important information required. This book will be devoted largely to the rate function r, its form and its meaning. Alternatively, the formulae collected in Table 1.8.1 are those that may be used to obtain the rate function from kinetic measurements in ideal reactors. 

In principle, continuously (or semicontinuously) operated catalytic slurry reactors represent an alternative to catalytic fixed bed reactors, with the main difference of a much smaller size of the solid catalyst particles. From the viewpoint of chemical reaction engineering, slurry reactors seem to be the most neglected ones by researchers today, as stated by van Landeghem by occasion of his status of the art report during ISCRE 6 [1]. 

Heterogeneous chemical reactions proceeding at the interface between the solid catalyst surface and the adjacent gas-phase are central to many chemical engineering applications. The catalyst basically provides an alternate reaction pathway by lowering the activation energy for the reaction as shown in Fig.2.1. The surface intermediates can react among themselves... 

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