Investigation of the effect of dead volume on the shape of breakthrough curve – New method designed to correct this effect

At laboratory scale, the reactor volume may be the same order of magnitude as the dead volume of the experimental set-up. The purpose of this study is to provide a new simple method to obtain a breakthrough curve on an inert porous media (without adsorption), corrected from the influence of the dead volume, to study only the effect of the axial dispersion. Indeed, our study parameters (pressure, low flow rate, fixed bed column filled with an inert porous media) did not allow us to use the classical and simple method, known as Point by Point (PBP). This new method (Elementary Surface Area ESA) is based on the substraction of elementary surfaces of dead volume and raw breakthrough curves, whereas the PBP method is built on a point by point substraction. Therefore, each elementary surface, defined by two points of the breakthrough curve, induces a smoothing of the fluctuations observed by the PBP method. So the ESA method could be considered as an inprovment of PBP one. Analysis of breakthrough curve requires calibration of the measurement devices for both flow rate and gas stream composition. Some calibration results are also presented in this paper. • Improvement of knowledge on the impact of dead volume on the shape of the breakthrough curve. • New model to correct the effect of dead volume on the raw breakthrough curve. • Recommendations for measuring gas flows in breakthrough curve studies.