The Effects of Mixing, Reaction Rates, and Stoichiometry on Yield for Mixing Sensitive Reactions—Part I: Model Development

Abstract

There are two classes of mixing sensitive reactions: competitive-consecutive and competitive-parallel. The yield of desired product from these coupled reactions depends on how fast the reactants are brought together. Recent experimental results have suggested that the mixing effect may depend strongly on the stoichiometry of the reactions. To investigate this, a 1D, dimensionless, reactiondiffusion model at the micromixing scale was developed. Assuming constant mass concentration and mass diffusivities, systems of PDE's were derived on a mass fraction basis for both types of reactions. Two dimensionless reaction rate ratios and a single general Damköhler number emerged from the analysis. The resulting dimensionless equations were used to investigate the effects of mixing, reaction rate ratio, and reaction stoichiometry. As expected, decreasing either the striation thickness or the dimensionless rate ratio maximizes yield, the reaction stoichiometry has a considerable effect on yield, and all three variables interact strongly.

A novel environmentally friendly process for depolymerization of hydrolysis lignin using Kraft cooking liquor: chemicals recoverable by the Kraft recovery cycle

“…For a reaction to occur, molecules need to come into close contact with each other. Having a sufficient degree of mixing is important in terms of achieving the chemical kinetics needed to produce new species, especially in mass transfer‐controlled reaction systems . The results of scale‐up experiments (LS_23) were compared with the results obtained for experimental run ZHL_12, since both samples were produced at the same temperature (170 °C).…”

“…Having a sufficient degree of mixing is important in terms of achieving the chemical kinetics needed to produce new species, especially in mass transfer-controlled reaction systems. 30 The results of scale-up experiments (LS_23) were compared with the results obtained for experimental run ZHL_12, since both samples were produced at the same temperature (170 °C). The M w of the final product of experiment LS_23 was 2392 Da, while that for ZHL_12 was 3200 Da.…”

Variable Smear Layer and Adhesive Application: The Pursuit of Clinical Relevance in Bond Strength Testing

“…Despite being ultra-mild in nature (pH 2.7), the SB in this study might have also benefitted from its active application method, which ensures a persistent collision of the reactants [39], and from its constituent Vitrebond Copolymer (Table 2), which promotes additional chemical bonding with HAp [40]. Therefore, the active double application of uncured SB resulted in significantly higher bond strength values with 180-grit SiC-prepared dentin ( p < 0.05).…”

Kinetics and Product Selectivity (Yield) of Second Order Competitive Consecutive Reactions in Fed-Batch Reactor and Plug Flow Reactor

“…The recent literature on product selectivity of competitive consecutive reactions is reported by Shah et al [3,4], which deals with "product selectivity with mixing, reaction rates, and stoichiometry. " As the reactions in actual are not necessarily always elementary [1], it is relevant to simulate the product selectivity of nonelementary second order competitive consecutive reaction schemes.…”