Effect of background reactant gradient on tracer dispersion:a case study of impulse injection of reactant into an open reactor

The paradox is well known that the residence time distribution (RTD) is not valid for the estimation of the conversion of a first-order reaction in an open tubular reactor. A case of delta-injection of reactive species into an open flow system is investigated theoretically in this paper. The analytical solution with the Laplace transform demonstrated that the conversion of a first order reaction is identical to that in a closed reactor under steady state. The effect of the background reactant concentration gradient addressed by the authors in a previous paper was employed to this case, and the numerical solution of the tracer dispersion based on this novel argument gave rise to a similar value of conversion, suggesting the validity of the concept and the significance of the subtle difference between RTDs determined with or without the presence of a background reactant in an open now system