A catalyst is a material which influences a chemical process so that it will proceed toward chemical equilibrium faster or more selectively, without consuming the catalyst. This is illustrated by the logo of ICAT where the blue part of the A in ICAT illustrates the energy barrier for the reaction without the catalyst. By the presence of the catalyst the barrier is strongly reduced, as illustrated by the red line, and the reaction will now proceed much faster towards equilibrium. Often several chemical reactions will take place at the same time, but if the catalyst is appropriately designed it will only lower the barrier for the desired reaction resulting in a much better selectivity and thereby a cleaner product.
Catalysts come in many forms.
In this manner an area of the active metal of 10-200 m 2 per gram catalyst can be achieved. The final catalyst may be formed into pellets or monoliths optimized for heat and mass transfer. Figure 1 shows the pellets for cleaning flue gasses together with a monolith catalyst for cleaning of the emission from for example powerstations. Figure 2 shows electron microprobe pictures of catalyst materials. The biologic catalysts, the enzymes, belong to this class and are responsible for most chemical processes in living organisms.