%0 Journal Article
%T The Effects of Mixing, Reaction Rates, and Stoichiometry on Yield for Mixing Sensitive Reactions¡ªPart II: Design Protocols
%A Syed Imran A. Shah
%A Larry W. Kostiuk
%A Suzanne M. Kresta
%J International Journal of Chemical Engineering
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/654321
%X Competitive-consecutive and competitive-parallel reactions are both mixing sensitive reactions where the yield of desired product depends on how fast the reactants are brought together. Recent experimental results have suggested that the magnitude of the mixing effect may depend strongly on the stoichiometry of the reactions. To investigate this, a 1D, dimensionless, reaction-diffusion model was developed at the micromixing scale, yielding a single general Damk£¿hler number. Dimensionless reaction rate ratios were derived for both reaction schemes. A detailed investigation of the effects of initial mixing condition (striation thickness), dimensionless reaction rate ratio, and reaction stoichiometry on the yield of desired product showed that the stoichiometry has a considerable effect on yield. All three variables were found to interact strongly. Model results for 12 stoichiometries are used to determine the mixing scale and relative rate ratio needed to achieve a specified yield for each reaction scheme. The results show that all three variables need to be considered when specifying reactors for mixing sensitive reactions. 1. Introduction Mixing-sensitive reactions are reactions which are particularly sensitive to the rate at which the reactants are brought together, that is, how fast they are mixed. These reactions are of two main types: the competitive-consecutive (C-C) reaction scheme, which involves two competing reactions where the second unwanted reaction consumes the desired product from the first reaction, and the competitive-parallel (C-P) reaction scheme, where two reactions compete for a limiting reagent, forming a desired and undesired product. The effects of mixing and relative reaction rates of the competing reactions have been investigated previously and it is known that mixing can affect the product distribution significantly. Past work has concentrated on the investigation of a single classical stoichiometry for each of the reaction schemes [1¨C25]. This work investigates whether the stoichiometry of the reaction plays a role in determining the maximum final yield of desired product and how the three reactor design variables¡ªmixing, reaction, rate and stoichiometry interact. In a previous paper by Shah et al. [26], a model was developed to capture the effects of reaction stoichiometry, mixing, (characterized by the Damk£¿hler number (Da)), and relative reaction rates, (characterized by a dimensionless reaction rate ratio ( / )). General forms of the reactions as given in Table 1 were used to derive mass balance equations. From the
%U http://www.hindawi.com/journals/ijce/2012/654321/