Kinetic laws fourth-order

The kinetics of the oxidation of a series of para- and meto-substituted benzaldehydes by quinolinium chlorochromate are first order in substrate, oxidant, and hydronium ion the results were subjected to a Taft analysis. Oxidation of 2-pyridinecarboxaldehyde to the acid by dichromate follows an unusual mixed fourth-order rate law it is first order in hydronium ion and Cr(VI), and second order in aldehyde. 

Third, the kinetic law shows no dependence on oxygen partial pressure but is straight first order in carbon monoxide partial pressure. Fourth, the temperatures at which the catalytic investigation was carried out were substantially higher, between 250° and 450°C. 

The Runge-Kutta-Gill fourth-order correct numerical integration algorithm for coupled ODEs is useful to simulate this double-pipe reactor after temperature-and conversion-dependent kinetic rate laws are introduced for both fluids. The generalized procedure is as follows ... 

Finally a fourth boundary condition shall be valid to support the worst case character of the procedure. The reaction order necessary for the formal kinetic description of a process has a severe influence on the pressure/time and respectively the tempera-ture/time-profiles to be expected. Industrial experience has shown that approximately 90% of all processes conducted in either batch or semibatch reactors can be described with a second order formal kinetic rate law. But it remains uncertain whether this statement, which is related to isothermal or isoperibolic operation with a rather limited overheating, remains valid if the reaction proceeds adiabatically and if side reactions contribute to the gross reaction rate at a much higher degree. In consequence, it shall be assumed for a credible worst case evaluation that the disturbed process follows a first order kinetics. Any reactions occurring in reality will almost certainly proceed at a much lower rate. 

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