Heterogeneous Catalysts

Heterogeneous Catalysts

Catalysts are essential essential for our society: our bodies and nature would not function without, but also they are key to provide our society with fuels, plastics, drugs, and they are essential to allow the transition from fossil to renewable building blocks. In our group we investigate the most common catalysts: solid (or “heterogenous”) catalyst, which often consist of supported metal nanoparticles.

Although the processes taking place on a catalyst surface concern atomic rearrangements and subatomic electronic structures, taking place on metal nanoparticles generally smaller than 10 nm, these active particles are stabilised on a porous/high surface area scaffold, which in turn can be shaped in pellets of extrudates with much larger sizes as generally they have to be thermally mechanically and chemically stable during operation at elevated temperatures and pressures in reactors that are up to several meters or even tens of meters in size.

Catalysts allow efficient chemical conversions. As shown in the picture they concentrate reactants, weaken the bonds in molecules by adsorption, stabilise intermediates, and steer the reaction to desorb the desired products. Catalysts are essential to minimise the use of energy and raw materials, as well as the production of greenhouse gases and side products.

Essential in a catalyst are activity ( for instance measured in turn-over-frequency (how many molecules are converted per second per surface metal atom) or more practically in moles or grams of product produced per gram of catalyst), selectivity (are only the reactants converted that we want to convert? Do we only produce the products that we want to make?) and stability (what is the lifetime of a catalyst?)

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