Designing mesoporous metallosilicate catalysts through aerosol-assisted sol-gel

Debecker, Damien P. [UCL]

Aerosol processes constitute an alluring technical platform for the continuous, large scale, and tailored production of divided nanomaterials, and in particular of advanced heterogeneous (nano)catalysts.1 In addition to the “simple” aggregation of preformed particles via spray drying, reactive aerosol processes allow synthesizing tailored-made catalysts with tunable surface properties, textures, compositions, surface functionalities, etc. In the “aerosol-assisted sol-gel” process (AASG), the inorganic polycondensation reactions are spatially and kinetically confined. Small droplets containing the molecular precursors are processed in seconds and transformed into the desired oxide particles. In addition, sol-gel reactions can be coupled with the evaporation-induced self-assembly (EISA) concept.2 This allows producing micronic or submicronic, inorganic or hybrid organic-inorganic particles bearing tunable and calibrated porous structures at different scales. Here, we will explain why this peculiar mode of preparation has led to high-performance solid nano-catalysts in various applications including olefin metathesis,3 lactate synthesis,4 olefin epoxidation,5 and dehydrogenation. In particular, we show how the method offers an excellent control over homogeneity, dispersion, surface functionalities, and texture. We will also demonstrate the concept of chemo-enzymatic heterogeneous catalysts obtained via spray techniques.6 Our objective is to demonstrate the tremendous possibilities offered by the coupling between bottom up sol-gel routes and aerosol processing technologies, which will arguably represent a major route of innovation not only in the field of catalyst preparation.