In the present work, a cell model is developed that is based on the film theory. In contrast to the existing pseudo-homogeneous models, the present approach retains a discreteness of the particles. The gas-liquid film is divided into cylindrical cells. The particles lie on the axes of the cells, and only those nearest to the interface contribute to the enhancement. The distance of these particles from the interface is exponentially distributed. The boundary element method is used to locate the reaction front. The computed flux is ensemble-averaged over the distribution of the particle locations. The effect of particle diameter and volume fraction of the solid on the enhancement factor is calculated. As the particles become finer, the enhancement factor increases significantly above the estimates of the pseudo-homogeneous models. An approximation to the cell model is also developed and is in good agreement with the rigorous model.