Second order reaction maximal rate

One of the major problems encountered in maximizing the flavor yields from cysteine-sugar systems is the high instability of the thiols diat are generated. The thiols do not only react with melanoidins but also widi each other (6, 2S). The result is that the characteristic meaty flavor disappears and a rubbery off-flavor is formed. Since the rates of the second-order reactions between the thiols are proportional to the square of the thiol concentrations, it is clear that products... 

Co—ONO complexes are formed by addition of Co—OH to N2 03(aq). Pearson, Henry, Berg-mann and Basolo140 first described the rate law, rate = [CoOH2] [HN02] [N02 ], and van Eldik and coworkers have recently confirmed the second-order dependence on [NO over a wide pH range.141 Murmann and Taube demonstrated retention of the Co—O bond by 180 tracer methods (equation 17).142 Other Co—OH l+ systems behave similarly and the reaction is relatively fast at room temperature and maximizes at a pH between 3 and 5. Specifically labelled complexes (e.g. Co—18ONO, Co—ONuO) have recently been made.143... 

Although these equations are simplifications of the actual chemical processes, the kinetic information is instructive. The second-order rate equations indicate that the reaction rates are directly proportional to the concentration of the reactants and the magnitude of the rate constants. Efforts to maximize these factors can lead to reactions that are more efficient. 

Because the second reaction is second order, in B, it is desirable to keep the average B concentration in the reactor low, to avoid yield losses, but achieve high B concentration near the reactor exit to maximize the production rate. Intuitively the CSTR is a bad choice, because it maintams the.same B concentration everywhere in the reactor. A PFR... 

The catalytic dehydration of isopropanol was studied under tiansirat conditimis in a catalytic microreactor. The reaction is characterised by educt inhibition and shows a pronounced stop-effect . Therefore, the average productivity under forced poiodic operation can be considerably higher compared to the maximal productivity obtainable at steady state. For high rates of the sorption processes and surface reactions involved, the timal cycle time for the forced concentration variations lies in the order of seconds. As microreactors are characterized by low mass storage capacity and narrow residence time distribution, they are particularly suitable for periodic operation at relatively high fiequencies. Tis could be demonstrated in the present study. 

---