Approximate model for diffusion and reaction in a porous pellet and an effectiveness factor

A heterogeneous dynamic model for the simulation and optimisation of the steam methane reforming reactor

“…CO þ H 2 O4CO 2 þ H 2 ð À DH 298 ¼ 41:2 kJ=molÞ (3) CH 4 þ 2H 2 O4CO 2 þ 4H 2 ; ð À DH 298 ¼ À165 kJ=molÞ (4) For reactions (2)e(4) a LangmuireHinshelwood mechanism can be established using NiMgAl 2 O 4 as a catalyst [2], which was used in the current work. Following Hill's method [3] it can be proven that only 2 reactions are independent, so that only two fractional conversions can be used, namely that of CO 2 and CH 4 :…”

“…Usually the particles are large so that the pressure drop is small, which leads to high mass transfer resistances in the particles [4]. For reactions (2)e(4) in industrial practice the effectiveness factors are very low (<0.03) due to high diffusional limitations in the solid porous network [5,6].…”

Transient effectiveness factors in the dynamic analysis of heterogeneous reactors with porous catalyst particles

“…Moreover, the need of solving the partial differential equations (PDEs) of the mass balances in the particle, which are coupled to the corresponding mass balances in the fluid phase, can be avoided since pseudo homogeneous systems outcomes. An important number of works exists where the effectiveness factor is studied and approximate expressions are developed to obtain fast estimations, or to extend the approach to different particle geometries or chemical reaction kinetics (Bischoff, 1965;Gonzo et al, 1988;Gottifredi et al, 1981;Gottifredi and Gonzo, 2005;Haynes, 1986;Lee and Kim, 2006;Szukiewicz and Petrus, 2004).…”

Dyfuzja z reakcją chemiczną – ocena dokładności przybliżonego modelu kinetycznego dla ziaren kulistych

“…Due to substantial inaccuracies with this equation, a number of other approximate kinetic equations were proposed. They referred both to the process of diffusion with adsorption [2][3][4][5] and diffusion with chemical reaction [6][7][8][9][10][11][12][13][14][15][16].…”