The computed axial velocity, temperature and mass fraction profiles along a line through the forward stagnation point for flow around a spherical VPO particle coupled with reaction inside the porous catalyst, as described in section 4.2, are exemplary shown for Re p = 1, 500 in Figure . Due to the no-slip boundary condition at the fluid-solid interface, the velocity approaches zero at the particle surface and artificial convective heat and species mass fluxes as in the porous media approach proposed by are prevented. Due to the exothermic reaction, the temperature increases inside the catalyst and near the particle surface. The temperature gradient is steeper at the fluid side of the interface than inside the particle, indicating that heat transport is limited by the heat transfer between fluid bulk and particle surface. In contrast, the limitation of species mass transport is larger inside the particle than at the fluid-solid interface, due to the influence of Knudsen diffusion on the intraparticle transport. This leads to steep gradients of mass fractions inside the particle and flat concentration profiles at the fluid side of the particle surface. The occurring reactions consume n-butane and consequently the fraction of C 4 H 10 decreases inside the catalyst. Within the near-surface region of the particle (0.0 < z/d p < 0.1), the formation of maleic anhydride is the dominant reaction and w MA increases. Since the transport of MA into the fluid phase is limited by pore diffusion, the formed maleic anhydride is partially further oxidized to CO and CO 2 in the inner region of the catalyst resulting in a reduction of w MA towards the particle center. The validity of applying the implemented conjugated heat and mass transfer model for coupling fluid flow with reaction within a porous catalyst is verified by the integral energy and material balances of the simulation. Therefore, the flow of energy and nbutane within the particle and at the fluid and solid side of the interface are calculated by integrating the source terms over the catalyst volume and the diffusive fluxes over the particle surface. Moreover, the overall change of energy and n-butane in the fluid phase is determined by mass-weighted integration of the fluxes over the inlet and outlet section of the fluid domain. Table lists the computed values for the laminar (Re p = 200) and turbulent (Re p = 1, 500) case. Due to the conservation of energy and species mass, the amount of all four computed values must be equal.