In this work, the inclusion of free sulfonic acid groups in highly stable MOFs is explored. The synthesized catalysts have been applied in a model esterification reaction. Two metal organic frameworks bearing sulfonic acid moieties are investigated: HSO 3-MIL-101(Cr) synthesized following different approaches and a new structure based on HSO 3-bdc and Zr. The acidic properties, catalytic performance, deactivation and stability of the different structures are critically evaluated. In the case of MIL-101(Cr), deactivation of the sulfonic groups via formation of butanol sulfonic esters has been observed. Due to the strong interaction between-SO 3 À and the Cr open metal site where usually fluorine (F À) is located in the structure, the HSO 3-MIL-101(Cr) catalysts are not stable under acidic regeneration conditions. When using Zr as a metal node, a new and stable sulfonic acid containing porous structure was synthesized. This structure showed high activity and full re-usability in the esterification of n-butanol with acetic acid. In this case, deactivation of the catalyst due to sulfonic ester formation could be reversed by reactivation under acidic conditions.

Field-scale simulation of flow in porous media in presence of incomplete mixing demands for high-resolution computational grids, much beyond the scope of state-of-the-art simulators. Hence, the upscaling-based Todd and Longstaff (TL) approach is typically used, where coarse grid cells are employed with effective mixing fluid properties and parameters found by matching results obtained with fully resolved reference simulations. Dynamic local grid refinement (DLGR) techniques, on the other hand, only employ fine-scale grid resolution where the fully mixed assumption is not valid. The rest of the domain is then solved at coarser resolutions, where the fully mixed assumption is valid. Here, we assess the accuracy and the robustness of DLGR-and TL-based simulations of miscible displacements in homogeneous and heterogeneous porous media. Due to the intrinsic uncertainty within the unstable displacement nature of the studied incomplete mixing processes, the performance of the methods is also investigated based on a range of acceptable solutions rather than relying only on a single reference one. Systematic numerical results illustrate that the DLGR method is much more robust and accurate than the upscaling-based TL approach, and employs only a small fraction of fine-scale reference grids. Especially, the TL upscaling results (though history matched with computationally expensive fine-scale results) are very sensitive to the change of the simulation parameters. Based on this study, we propose a dynamic multilevel simulation strategy for efficient and reliable large-scale simulation of the complex incomplete mixing processes. Keywords Incomplete mixing in porous media • Dynamic local grid refinement • Todd-Longstaff model • Algebraic dynamic multilevel method • Viscous fingering