Non-Markovian diffusion equation and diffusion in a porous catalyst


We revisit the problem of diffusion in a porous catalyst by incorporating in the diffusion equation fractional time derivatives and a spatial dependent diffusion coefficient in order to extend the usual description to situations which have an unusual behavior. In our analysis, we also consider a nonlocal reactiontermoflinearorder.Weobtainexact solutions for theprofileof substance intheporous catalyst in terms ofthe Green function approach. The results show an anomalous behavior ofthe concentration profile spreading which may be connected to anomalous diffusion.