The metal–organic framework Cu–BTC has been successfully synthesized as nanoparticles inside the mesopores of silica monoliths featuring a homogeneous macropore network enabling the use of Cu–BTC for continuous flow applications in liquid phase with low pressure drop. High productivity was reached with this catalyst for the Friedländer reaction.

Silica monoliths with hierarchical porosity (macro-/mesoporous), prepared by a combination of phase separation (spinodal decomposition) and sol–gel process, have demonstrated remarkable potential as supports for catalysts and adsorbents with improved efficiency and productivity of a number of applications. This is due to perfect homogeneous interconnected porous networks enabling an exceptional mass transfer and a fine control of contact times. Silica monoliths have been functionalized by an important variety of moities and techniques, such as grafting with versatile species (acidic, basic), by alumina coating, immobilization of ionic liquids, in-situ synthesis of nanoparticles of Pd, MOF, and NiMoS ₂ , pseudomorphic transformation of the skeleton into MCM-41 or zeolites (SOD, LTA). These functional materials reveal great opportunities for process intensification.

This contribution reviews the preparation, main characteristics and advantages of macroporous monolithic microreactors for the synthesis of fine chemicals by continuous flow catalytic processes. The review focuses on different types of monolith (polymers, polymer/glass, silica, zeolites) exhibiting macropores of typically 2 to 10 μm, a large pore volume (1–2 mL g⁻¹) and a high surface area (>300 m² g⁻¹) that can be readily functionalized by a variety of active moieties. With respect to traditional batch and packed-bed reactors, monolithic reactors allow easier process implementation, higher productivity and improved selectivity.