Computational fluid dynamics (CFD) simulations of a reactive catalytic layer of micrometer-sized particles with a submicrometer interparticle distance for decane oxidation are described. The investigation used two main approaches. The heterogeneous approach simulates particles at the reactive particle surface, by use of a monodispersed face-centered cubic structure of eight unit cells in series. In contrast, the pseudohomogeneous approach investigates the particle system as a homogeneous system (approximation) having dimensions and geometrical properties (tortuosity and porosity) identical to those of the heterogeneous one. Heterogeneous system results show that mass transfer resistance can be regarded as negligible in the whole range of parameters investigated (temperature and interparticle distance). Particularly, the difference in results obtained by the two approaches is negligible up, to the highest temperature considered (400 degrees C), with a maximum discrepancy of about 2.4%. An analogous result is found through study of the effect of interparticle distance, which indicates that, under the conditions investigated, the pseudohomogeneous approach can be used effectively to simulate particle systems with micrometer-order length and submicrometer interparticle distance.